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Transcutaneous Oximetry in Clinical Practice: Consensus statements from an expert panel based on evidence
Abstract
Transcutaneous oximetry (PtcO2) is finding increasing application as a diagnostic tool to assess the peri-wound oxygen tension of wounds, ulcers, and skin flaps. It must be remembered that PtcO2 measures the oxygen partial pressure in adjacent areas of a wound and does not represent the actual partial pressure of oxygen within the wound, which is extremely difficult to perform. To provide clinical practice guidelines, an expert panel was convened with participants drawn from the transcutaneous oximetry workshop held on June 13, 2007, in Maui, Hawaii. Important consensus statements were (a) tissue hypoxia is defined as a PtcO2 <40 mm Hg; (b) in patients without vascular disease, PtcO2 values on the extremity increase to a value >100 mm Hg when breathing 100% oxygen under normobaric pressures; (c) patients with critical limb ischemia (ankle systolic pressure of < or =50 mm Hg or toe systolic pressure of < or =30 mm Hg) breathing air will usually have a PtcO2 <30 mm Hg; (d) low PtcO2 values obtained while breathing normobaric air can be caused by a diffusion barrier; (e) a PtcO2 <40 mm Hg obtained while breathing normobaric air is associated with a reduced likelihood of amputation healing; (f) if the baseline PtcO2 increases <10 mm Hg while breathing 100% normobaric oxygen, this is at least 68% accurate in predicting failure of healing post-amputation; (g) an increase in PtcO2 to >40 mm Hg during normobaric air breathing after revascularization is usually associated with subsequent healing, although the increase in PtcO2 may be delayed; (h) PtcO2 obtained while breathing normobaric air can assist in identifying which patients will not heal spontaneously.
... Transcutaneous oxygen testing was performed with PeriFlux 5000 (Perimed AB, Järfälla, Sweden). TcPO 2 provides information about the body's ability to deliver oxygen to tissues based on the amount of oxygen diffusing from the capillaries through the epidermis to the electrode [17,21]. To measure TcPO 2 , sensors contain a pair of polarizing electrodes to determine the current oxygen content of a given volume. ...
... Transcutaneous oxygen testing was performed with PeriFlux 5000 (Perimed AB, Sweden). TcPO2 provides information about the body's ability to deliver oxygen to tissues based on the amount of oxygen diffusing from the capillaries through the epidermis to the electrode [17,21]. To measure TcPO2, sensors contain a pair of polarizing electrodes to determine the current oxygen content of a given volume. ...
... They are separated by a liquid electrolyte. The electrodes are separated by a polymeric membrane, which allows oxygen to selectively permeate from the area of skin tested [21]. The output current is proportional to tissue oxygen partial pressure [19] and skin blood flow, oxyhemoglobin dissociation, and tissue metabolic activity. ...
This study aimed to evaluate the earliest changes in the structure and function of the peripheral microcirculation using capillaroscopy and transcutaneous oxygen pressure measurement in children and adolescents with type 1 diabetes mellitus at baseline and during post-occlusive reactive hyperemia (PORH) in the function of diabetes duration. Sixty-seven patients with type 1 diabetes mellitus (T1D), aged 8 to 18 years, and twenty-eight age- and sex-matched healthy subjects were included in the analysis. Diabetic patients were divided into subgroups based on median disease duration. The subgroups differed in chronological age, lipid levels, and thyroid hormones. Capillaroscopy was performed twice: at baseline and then again after the PORH test. Transcutaneous oxygen pressure also was recorded under baseline conditions during and after the PORH test. Comparison of capillaroscopy and transcutaneous oxygen pressure parameters at rest and after the PORH showed no statistically significant difference between the subgroups. This remained true after adjusting for variables that differentiated the two subgroups. However, in the group of patients with long-standing diabetes, significant negative correlations were observed between the Coverage value after the PORH test and capillary reactivity with TcPO2_zero (biological zero). Significant positive correlations were also found between distance after the PORH test and TcPO2_zero. The results of our study indicate that in patients with a shorter duration of diabetes, the use of multiple tests provides a better characterization of the structure and function of microcirculation because the onset of dysfunction does not occur at the same time in all the tests.
... SVS-WIfI incorporates the measurement of toe pressures or transcutaneous oxygen pressure (TcPO2) for patients with ABI >1.3, which indicates noncompressible arteriopathy. TcPO2 above 30 mmHg is a predictive factor for spontaneous healing with TcPO2 <10 mmHg associated with unfavorable course of wound healing [8]. SVS-WIfI also specifically delineates ulceration versus gangrene, with the latter portending to a worst prognosis [1]. ...
... Limb salvage in the setting of diabetic foot infections and CLTI requires a prolonged course of intensive care, requiring podiatrists for prevention and early wound care, vascular or general surgeons for debridement and eventual revascularization, infectious disease providers for antibiotic management and stewardship, wound care nurses and providers for intervening wound care before and between staged surgical interventions, and primary care providers for medical management and optimization of comorbid conditions. Regenerative medicine is an emerging discipline that incorporates the use of biologic materials stem cells, growth factors, anti-inflammatory cytokines and extracellular matrix in order to restore impaired function by stimulating regeneration of cells, tissues, or organs [4,5,8,[10][11][12][13][14]. Normal wound healing occurs with multiple overlapping phases including early inflammation followed by the proliferative phase, which includes granulation tissue formation, epithelialization and angiogenesis, followed by remodeling [16,17]. ...
... At our facility, we use a combination of stem cell grafts, extracellular matrix components, and wound matrix applied in a specific order to maximally prepare the wound bed. The goals for optimizing the wound for healing include producing a well-vascularized bed controlling infection and inflammation resulting in a minimal amount of exudate [8]. In this patient, the wound bed was prepared with ultrasonic debridement which uses lowfrequency ultrasound waves to produce atraumatic selective tissue debridement and decrease inflammatory cytokines [15]. ...
... First, the TcPO 2 measured while breathing normobaric room air can be used to predict healing and response to HBO 2 [37][38][39][40]. Measurements less than 40 mmHg are defined as hypoxic and are associated with a reduced likelihood of healing. ...
... Measurements less than 40 mmHg are defined as hypoxic and are associated with a reduced likelihood of healing. Second, TcPO 2 values that are less than 35 mmHg while breathing 100% normobaric oxygen are associated with a 41% failure rate with HBO 2 [39]. Third, wounds that are hypoxic on room air (TcPO 2 <40 mmHg) and have a TcPO 2 increase while breathing 100% normobaric oxygen that is both above 35 mmHg and >50% above the normobaric air value are likely to benefit from HBO 2 (associated with a 69% chance of beneficial response) [39]. ...
... Second, TcPO 2 values that are less than 35 mmHg while breathing 100% normobaric oxygen are associated with a 41% failure rate with HBO 2 [39]. Third, wounds that are hypoxic on room air (TcPO 2 <40 mmHg) and have a TcPO 2 increase while breathing 100% normobaric oxygen that is both above 35 mmHg and >50% above the normobaric air value are likely to benefit from HBO 2 (associated with a 69% chance of beneficial response) [39]. Finally, the most valuable predictor of response to HBO 2 is an in-chamber TcPO 2 [38]. ...
Background and objective:
Diabetic kidney disease (DKD) is the most common microvascular chronic complication of diabetes mellitus. Hyperbaric oxygen (HBO2) therapy will increase the partial pressure of oxygen (PaO2) and may improve cell repair processes, which can lead to better renal function. The objective of this study was to quantify the efficacy of adjuvant HBO2 to increase the glomerular filtration rate and urinary albumin excretion in diabetic patients, as well as determine its effectiveness to modify the clinical course of DKD.
Materials and methods:
An experimental study was performed on patients with stage 3 and 4 DKD. Twenty sessions of HBO2 or ambient air in a hyperbaric chamber were administered. Estimated glomerular filtration rate, urine albumin:creatinine ratio calculation and clinical stage stratification were made prior to and after HBO2 administration. A descriptive, inferential and clinical efficacy analysis was performed.
Results:
Urinary albumin/creatinine (UACR) mean values prior to HBO2 were 1452.9 ± 644.3 mg/g and decreased to 876.1 ± 504.0 mg/g at the end of the study (p=0.06). The patients in the control group showed a UACR mean of 2784.5 ± 2128.6 mg/g and 2861.4 ± 2424.2 mg/g at baseline and at the end of the study, respectively (p=0.82). Patients in the experimental/HBO2 group showed an estimated GFR of 27.3 ± 9.5 mL/min /1.73m2 before HBO2, with a 34.4 ± 6.9 mL/min/1.73m2 after treatment (p=0.017); control group eGFR was 30.1 ± 9.2 mL/min/1.73m2, decreasing to 22.2 ± 6.8 mL/min/1.73m2 (p=0.004). Relative risk 0.00, relative risk reduction -100%, absolute risk reduction -71.4%, 95% CI (-104.9% to -38.0%), NNT 1, 95% CI (1 to 3).
Conclusions:
Management with HBO2 for DKD was associated with decreased excretion urinary albumin, improved GFR and clinical stage of patients in stages 3 and 4 of kidney damage unlike those receiving ambient air..
... Transcutaneous oximetry can be used to estimate the amount of oxygen reaching the wound being delivered by the small vessels (microvasculature) to the skin (Table 11). 67 The technique involves placing a probe heated to 44°C to 45°C on the skin and measuring the level of oxygen in the skin immediately under the probe. 68 The probe is normally placed adjacent to the wound site, and a normal result would be >70 mm Hg on the foot at rest with higher values proximally. ...
... 68 The probe is normally placed adjacent to the wound site, and a normal result would be >70 mm Hg on the foot at rest with higher values proximally. 67 Higher TcPO 2 values are predictive of improved rates and speed of healing. [69][70][71][72][73] Values of <40 mm Hg are associated with impaired wound healing, while pressures <30 mm Hg are associated with rest pain, gangrene, and arterial ulceration. ...
... Methods such as TP, or TBI, will detect changes in small vessel blood flow; however, the equipment is more costly and less available to practitioners. 33 Similarly, TcPO 2 is able to directly test tissue perfusion surrounding the wound, taking into account both macrovascular and microvascular influences in predicting wound healing, 67 and it is not compromised by presence of underlying diseases like diabetes or kidney disease. 82 ...
Arterial investigations are an essential part of lower extremity wound assessment. The results of these investigations assist the wound clinician to determine the etiology of the wound, predict healing capacity, and inform further management. There are a number of noninvasive testing methods available to practitioners, all with varying levels of reliability and accuracy. Clinical wound assessment guidelines give varied recommendations when it comes to lower limb vascular assessment in the presence of a wound. This leaves clinicians with little guidance on how to choose the most appropriate test, and uncertainty remains about which tests provide the most accurate information in different patient-specific contexts. Conditions such as advanced age, diabetes, and renal disease are known to affect the accuracy of some commonly used lower limb arterial assessment methods, and alternate testing methods should be considered in these cases. This seminal review discusses the reliability and accuracy of lower limb vascular assessment methods used to guide lower limb arterial assessment in the presence of wounds.
... For example, arterial noncompressibility makes the ankle-brachial index (ABI) non-meaningful in a significant minority of patients with CLI, and transcutaneous oximetry has a high coefficient of variation. [5][6][7][8][9] Intraprocedural measures of foot perfusion are attractive to the interventionalist to direct the target and extent of revascularization, and measures such as 'angiographic blush' have been reported to correlate with wound healing. 10 However, 'angiographic blush' is somewhat subjective and dependent on technique. ...
... 32 Also, during TcPO 2 measurement, 100% oxygen can be administered in such cases where the TcPO 2 value should rise to greater than 100 mmHg, whereas less than 30 mmHg is consistent with PAD. [6][7][8] This 'oxygen challenge' might distinguish low pCO 2 values due to PAD versus barriers to diffusion, which can include edema, inflammation leading to increased oxygen consumption, vasoconstriction from cold exposure or dehydration, and calluses. For example, a TcPO 2 value less than 30 mmHg in ambient air and greater than 100 mmHg on 100% oxygen suggests adequate arterial inflow but the presence of a local barrier to oxygen diffusion. ...
... For example, a TcPO 2 value less than 30 mmHg in ambient air and greater than 100 mmHg on 100% oxygen suggests adequate arterial inflow but the presence of a local barrier to oxygen diffusion. 7,33 Clinically, TcPO 2 can assess the severity of PAD, need for revascularization, potential wound healing, and response to revascularization. 6,9,30,31,[34][35][36][37][38][39] Data suggest TcPO 2 is superior to other physiologic vascular studies for predicting wound healing, especially in those with diabetes or renal failure. ...
Patients with critical limb ischemia have nonhealing wounds and/or ischemic rest pain and are at high risk for amputation and mortality. Accurate evaluation of foot perfusion should help avoid unnecessary amputation, guide revascularization strategies, and offer efficient surveillance for patency. Our aim is to review current modalities of assessing foot perfusion in the context of the practical clinical management of patients with critical limb ischemia.
... Transcutaneous tissue oximetry (TcPO2) is a non-invasive method for measuring oxygen pressure on the skin surface to assess peripheral vascular oxygenation and microcirculation. Values below 40 mm Hg are considered pathologically low or hypoxic, which can slow or reduce wound healing, while values above 40 mm Hg are considered normal [10][11][12][13]. PAD increases the risk of cardiovascular disease and death, and these risks are even higher when diabetes is associated with PAD [14]. ...
... TcPO2 is a better predictor for ulcer healing than the toe-brachial index in patients with diabetes with chronic foot ulcers [27]. According to the consensus of professional societies, TcPO2 values below 40 mm Hg represent hypoxia of the skin and subcutaneous tissues of the foot, which slows and prevents wounds or residual limbs from healing, while values of 40 (50) mm Hg or higher are considered normal findings [10][11][12][13]28]. In patients with TcPO2 values below 40 mm Hg, it is recommended to measure the TcPO2 additionally after elevating the legs. ...
The results of large cardiovascular studies indicate that SGLT-2 inhibitors may increase the risk of leg amputations. This study aims to investigate whether dapagliflozin therapy affects peripheral vascular oxygenation, i.e., microcirculation in the foot, as measured by transcutaneous oxygen pressure (TcPO2) in patients with type 2 diabetes (T2DM) and peripheral arterial disease (PAD) compared to patients without PAD. The patients with PAD were randomized into two groups. In the first 35 patients with PAD, dapagliflozin was added to the therapy; in the other 26 patients with PAD, other antidiabetic drugs were added to the therapy. Dapagliflozin was added to the therapy in all patients without PAD. TcPO2 measurement, Ankle Brachial Index (ABI), anthropometric measurements, and laboratory tests were performed. After a follow-up period of 119.35 days, there was no statistically significant difference in the reduction of mean TcPO2 values between the group with T2DM with PAD treated with dapagliflozin and the group with T2DM with PAD treated with other antidiabetic drugs (3.88 mm Hg, SD = 15.13 vs. 1.48 mm Hg, SD = 11.55, p = 0.106). Patients with control TcPO2 findings suggestive of hypoxia (TcPO2 < 40 mm Hg) who were treated with dapagliflozin had a clinically significant decrease in mean TcPO2 of 10 mm Hg or more (15.8 mm Hg and 12.90 mm Hg). However, the aforementioned decrease in TcPO2 was not statistically significantly different from the decrease in TcPO2 in the group with PAD treated with other diabetic medications (p = 0.226, p = 0.094). Based on the available data, dapagliflozin appears to affect tissue oxygenation in T2DM with PAD. However, studies with a larger number of patients and a longer follow-up period are needed to determine the extent and significance of this effect.
... Several techniques are currently available to determine tissue perfusion in the lower extremity. Transcutaneous oxygen pressure (TcPo 2 ) measurement is the most commonly used technique for tissue perfusion [1,[3][4][5][6][7][8]. Unfortunately, this technique is time consuming, operator dependent, and the level of high-quality evidence remains low [2,9,10]. ...
... TcPo 2 measurements were also performed to determine tissue perfusion [8]. The mean TcPo 2 values exceeded the minimal 50 mm Hg, which is considered normal in healthy subjects [7]. The ICC of TcPo 2 measured at different days was low, underlining the large variation in normal tissue perfusion in healthy participants on different days. ...
Purpose:
Hyperspectral imaging (HSI) is a noninvasive spectroscopy technique for determining superficial tissue oxygenation. The HyperView™ system is a hand-held camera that enables perfusion image acquisition. The evaluation of superficial tissue oxygenation is warranted in the evaluation of patients with peripheral arterial disease. The aim was to determine the reliability of repeated HSI measurements.
Methods:
In this prospective cohort study, HSI was performed on 50 healthy volunteers with a mean age of 26.4 ± 2.5 years, at the lower extremity. Two independent observers performed HSI during two subsequent measurement sessions. Short term test-retest reliability and intra- and inter-observer reliability were determined, and generalizability and decision studies were performed. Transcutaneous oxygen pressure (TcPO2) measurements were also performed.
Results:
The short term test-retest reliability was good for the HSI values determined at the lower extremity, ranging from 0.72 to 0.90. Intra- and inter-observer reliability determined at different days were poor to moderate for both HSI (0.24 to 0.71 and 0.30 to 0.58, respectively) and TcPO2 (0.54 and 0.56, and 0.51 and 0.31, respectively). Reliability can be increased to >0.75 by averaging two measurements on different days.
Conclusion:
This study showed good short term test-retest reliability for HSI measurements, however low intra- and inter-observer reliability was observed for tissue oxygenation measurements with both HSI and TcPO2 performed at separate days in young healthy volunteers. Reliability of HSI can be improved when determined as a mean of two measurements taken on different days.
... Increased oxygenation of tissues causes accelerated regeneration of ischemic skin fragments, faster wound granulation, and epidermization, as well as be improved arterial and venous blood flow in tissues. 14,28 Enhancement of local oxygenation of tissues has currently been an ever more emphasized standard of therapeutic management in case of diseases affecting peripheral vessels, including chronic venous leg ulcers. In order to assess the effectiveness of therapy in that respect, monitoring of oxygen partial pressure values in tissues is of considerable importance. ...
... The absence of growth in oxygen partial pressure above 10 mm Hg in case of exposure to 100% oxygen with the pressure of 1 ATA entails critical ischemia of tissues, which is usually connected with lack of positive response to the hyperbaric therapy applied. [28][29][30] In the study by Trinks et al, the usefulness of transcutaneous oximetry for assessment of oxygen partial pressure (tPCO 2 ) has been confirmed, and it has also been demonstrated that the average value of that parameter, measured on the surface of lower leg in young (younger than 40 years of age) healthy volunteers is 61.5 mm Hg. 29 Taking into account the fact that in the group of patients with chronic venous ulcers of the lower leg, which we analyzed in our study, the mean value of oxygen partial pressure in tissues surrounding the ulceration before treatment amounted to 68.63 ± 17.04 mm Hg should be assumed that those tissues have not been substantially hypoxemic. ...
Venous ulcers in lower legs remain a profound treatment problem in contemporary medicine. Proper healing requires, among other things, sufficient blood supply and provision of suitable amount of oxygen to the treated tissues. The aim of the study was to assess the influence of combined physical therapy applied in patients with chronic venous leg ulcers on the oxygen partial pressure values. Fifty-four patients (25 females and 29 males), in the age range of 38 to 89 years with chronic venous leg ulcers, underwent a cycle of 15 procedures with the use of Laserobaria-S device. During a procedure, the patient’s lower limb was simultaneously exposed to oxygen having the pressure of 1.5 ATA, low-frequency magnetic field, and low-energy light radiation. Before procedures, directly after the first procedure, as well as on completion of the entire therapeutic cycle, the patients underwent oxygen partial pressure measurements in the tissues surrounding the ulceration area, by means of transcutaneous oximetry, with the use of Medicap Précise 8008s device. The combined physical therapy shows a statistically significant increase of oxygen partial pressure values in tissues surrounding the ulceration, from the average of 68.63 ± 17.04 mm Hg before commencing the therapeutic cycle, to the average of 74.20 ± 18.92 mm Hg after the first procedure ( P < .001) and to the average value of 83.79 ± 20.74 mm Hg ( P < .001) after completion of therapeutic cycle. Combined physical therapy procedures cause a statistically significant increase of oxygen partial pressure values in tissues surrounding the ulceration, assessed using the objective method of transcutaneous oximetry, both in women and men.
... The consistent evidence demonstrating the association between TcPO 2 levels below 30 mmHg and poor healing outcomes, as well as the increased risk of lower limb amputation in diabetic patients, underscores its clinical relevance. Moreover, this non-invasive methodology provides valuable information regarding skin perfusion and microcirculatory responses, thereby facilitating treatment decision-making and prognostication in the management of DFU (42)(43)(44)(45). ...
Background and Objective
Diabetic neuropathy significantly elevates the risk of foot ulceration and lower-limb amputation, underscoring the need for precise assessment of tissue perfusion to optimize management. This narrative review explores the intricate relationship between sympathetic nerves and tissue perfusion in diabetic neuropathy, highlighting the important role of autonomic neuropathy in blood flow dynamics and subsequent compromises in tissue perfusion. The consequences extend to the development of diabetic peripheral neuropathy and related foot complications. By analyzing both non-invasive diagnostic methods and surgical interventions, such as tarsal tunnel decompression, the paper seeks to highlight their effectiveness in improving tissue perfusion, preventing ulcers, and reducing the risk of amputations in patients with diabetic peripheral neuropathy.
Methods
We reviewed current literature on both non-invasive diagnostic tools and surgical techniques for assessing and improving tissue perfusion in diabetic neuropathy. Methods discussed include transcutaneous oxygen pressure (TcPO2), Doppler ultrasound, Tissue-Muscle Perfusion Scintigraphy with 99mTc-MIBI, and the SPY Laser Angiographic System.
Key Content and Findings
Emphasizing the critical importance of surgical interventions, such as tarsal tunnel decompression and neurolysis of the posterior tibial nerve, the article underscores their efficacy in enhancing tissue perfusion and preventing ulcers and amputations. Additionally, it addresses the significance of precise blood flow measurement and timely intervention in the management of diabetic neuropathy and foot ulcers. The non-invasive techniques for assessing tissue perfusion and blood flow in diabetic neuropathy such as TcPO2, Doppler ultrasound and Tissue-Muscle Perfusion Scintigraphy with 99mTc-MIBI are explained. Also, this review introduces the SPY Laser Angiographic System, which employs near-infrared fluorescence imaging to assess blood flow and perfusion in tissues. This advanced tool generates real-time microvascular blood flow images and proves instrumental in diagnosing and monitoring diabetic foot ulcers.
Conclusions
In conclusion, surgical interventions, both vascular and peripheral nerve are pivotal for optimizing patient care. Early identification of foot ulcers and peripheral arterial disease is imperative, and an understanding of blood flow dynamics, combined with effective surgical techniques, constitutes key elements in managing diabetic neuropathy, healing and preventing ulcers, and limb salvage.
... Os valores de PtcO 2 tendem a aumentar proximalmente. 4 ...
### Abstract
This chapter provides an in-depth overview of advanced diagnostic tools in vascular medicine, referred to as *Propedêutica Arterial Armada*. It emphasizes the integration of modern technologies, such as ultrasonography, angiography, and tomography, with traditional methodologies to enhance diagnostic accuracy for arterial pathologies.
The chapter categorizes and describes each tool, including its applications, techniques, and advantages. Methods like Doppler ultrasound and plethysmography enable detailed evaluation of blood flow, while angiotomography and angiography provide precise anatomical and functional imaging. The evolution of minimally invasive procedures, such as digital subtraction angiography (DSA) and intravascular ultrasonography (IVUS), is highlighted, showcasing their role in improving visualization of vascular abnormalities.
Attention is given to the benefits and limitations of these methods, including considerations for patient safety, such as radiation exposure and contrast-induced nephropathy. Detailed procedural guidelines and clinical scenarios illustrate how these techniques are applied in diagnosing aneurysms, arterial stenosis, and other vascular conditions.
This comprehensive discussion serves as a resource for clinicians, demonstrating the critical role of advanced vascular diagnostics in contemporary medical practice.
... In the patients with the diabetic foot syndrome, it is possible to objectify, using this method, the extremities ischemia level, as the other blood pressure measurement methods can indicate artificially high blood pressure values in the lower extremities in mediocalcinosis (Fife et al. 2009). ...
... Based on this, hypoxia of the lower limbs was defined as a PtcO 2 of less than 40 mmHg in non-diabetic patients. 1,6 A recent study reported TCOM values lower than those previously reported and raised the question as to whether the use of different measurement equipment influences obtained TCOM data. That study has now been retracted after discovering an instrumentation error that renders the measurements from the study unreliable. ...
Trinks TP, Blake DF, Young DA, Thistlethwaite K, Vangaveti VN. Transcutaneous oximetry measurements of the leg: comparing different measuring equipment and establishing values in healthy young adults. Diving and Hyperbaric Medicine. Introduction: Transcutaneous oximetry measurement (TCOM) is a non-invasive method of determining oxygen tension at the skin level using heated electrodes. Aim: To compare TCOM values generated by different machines and to establish lower limb TCOM values in a cohort of healthy individuals younger than 40 years of age. Method: Sixteen healthy, non-smoking volunteers aged 18 to 39 years were recruited. TCOM was obtained at six locations on the lower leg and foot using three different Radiometer machines. Measurements were taken with subjects lying supine, breathing air. Results: Except for one sensor site, there were no statistical differences in measurements obtained by the different TCOM machines. There was no statistical difference in measurements comparing left and right legs. Room air TCOM values for the different lower leg sites were (mean (SD) in mmHg): lateral leg 61.5 (9.2); lateral ankle 61.1 (9.7); medial ankle 59.1 (10.8); foot, first and second toe 63.4 (10.6); foot, fifth toe 59.9 (13.2) and plantar foot 74.1 (8.8). The overall mean TCOM value for the lower limb was 61 (10.8; 95% confidence intervals 60.05-62.0) mmHg. Conclusion: Lower-leg TCOM measurements using different Radiometer TCOM machines were comparable. Hypoxia has been defined as lower-leg TCOM values of less than 40 mmHg in non-diabetic patients and this is supported by our measurements. The majority (96.9%) of the lower leg TCOM values in healthy young adults are above the hypoxic threshold.
... Transcutaneous oximetry is a noninvasive method used to determine peripheral tissue perfusion at the capillary level based on measurement of the partial pressure of oxygen diffusing through the skin. 8 The project aims to evaluate the impact of profundoplasty as an isolated angiosurgical procedure in patients with symptomatic PAD associated with PFA stenosis and SFA closure when distal bypass is not possible due to poor performance of popliteal/tibial arteries. ...
... For instance, the approach to HBOT for diabetic foot ulcers, which includes predicting the effectiveness of HBOT and determining the duration of treatment, benefits not only from the clinical experience but also from objective assessments like transcutaneous oxygen and ultrasound measurements. These can facilitate a more refined, personalized approach to HBOT [4] . Currently, the use of HBOT to address skin necrosis caused by HA fillers primarily relies on clinical symptoms, such as color changes and absent capillary refill, to indicate ischemia [1,2] . ...
Introduction
Hyaluronic acid (HA) fillers, popular for facial cosmetic enhancements, pose risks of vascular complications like skin necrosis due to arterial blockage, necessitating effective treatments such as hyperbaric oxygen therapy (HBOT).
Methodology
This study presents a series of cases where measurements of transcutaneous oxygen pressure (TcPO 2 ) informed the application of HBOT for skin necrosis induced by HA.
Clinical presentation and outcomes
In cases 1 and 3, following the injection of HA, potential skin necrosis was observed. In addition to standard treatment, TcPO 2 revealed values below 40 mmHg, indicating tissue hypoxia. Treatment with HBOT increased TcPO 2 levels to above 200 mmHg, suggesting that HBOT could correct the hypoxia. Monitoring TcPO 2 levels also aided in determining the optimal time to discontinue HBOT. In cases 2 and 4, patients received standard treatment, resulting in TcPO 2 levels above 40 mmHg, indicating adequate tissue oxygenation, and no additional HBOT was administered. All four patients mentioned above showed good clinical recovery.
Conclusion
This study investigates the application of TcPO 2 measurement technology in aiding decisions on whether to utilize HBOT in the treatment of complications arising from HA fillers, as well as in optimizing HBOT protocols.
... The transcutaneous oxygen test used the PeriFlux 5000 instrument (Perimed AB, Järfälla, Sweden). TcPO 2 is based on the amount of oxygen that diffuses from the capillaries through the epidermis to the electrode and provides information about the body's ability to deliver oxygen to the tissues [60,61]. The principle of measuring the transcutaneous partial pressure of oxygen was presented in detail previously [26,37,52]. ...
Gender, through genetic, epigenetic and hormonal regulation, is an important modifier of the physiological mechanisms and clinical course of diseases. In diabetes mellitus, there are gender differences in incidence, prevalence, morbidity, and mortality. This disease also has an impact on the microvascular function. Therefore, this cross-sectional study was designed to investigate how gender affects the cutaneous microcirculation. We hypothesized that gender should be an important factor in the interpretation of capillaroscopy and transcutaneous oxygen saturation results. The study group consisted of 42 boys and 55 girls, uncomplicated diabetic pediatric patients. Females (F) and males (M) did not differ in terms of age, age at onset of diabetes, or diabetes duration. Furthermore, they did not differ in metabolic parameters. The comparison showed that group F had lower BP, higher pulse, and higher HR than group M. Group F had significantly lower creatinine and hemoglobin levels than group M. In children and adolescents with type 1 diabetes without complications, there was a gender difference in microcirculatory parameters. The resting transcutaneous partial pressure of oxygen was significantly higher in females than in males. However, there were no gender-related differences in basal capillaroscopic parameters or vascular reactivity during the PORH test. Our results indicate that studies investigating the structure and function of the microcirculation should consider the role of gender in addition to known cofactors such as puberty, body mass index, physical activity, and cigarette smoking.
... The measurement can be made in any part of the body, but the most common choice is the skin of the sole surface of the foot. A tcpO2 between 50 and 70 mm Hg is considered a reference range [60,61]. TcpO2 is an old, well-studied, simple, reproducible, but unfortunately, time-consuming method of assessing microcirculation, which has been used for many years in the evaluation of vascular diseases (such as evaluating wound healing or the effectiveness of revascularization) [62]. ...
BACKGROUND: Skin microcirculation is considered an easily accessible vascular bed, which can potentially be representative and helpful in evaluating, understanding the mechanisms of microvascular function and detection of its dysfunction. Many studies claim that functional changes in cutaneous circulation precede the development of arterial hypertension (HT). Identifying them at an early stage can enhance patients’ prognosis. There are methods which can be applied for these purposes. We aimed to describe available methods of skin microcirculation assessment, in the context of HT. MATERIAL AND METHODS: The PubMed database was searched till March 2022. Research articles used in the systematic review were experimental articles, reviews and abstracts from conference materials that reported the methods of the microcirculation assessment. From 1131 records, 47 articles were included in the final review. RESULTS: This review identified that the microcirculation examined with various methods was dysfunctional in HT patients. Standard HT treatment usually helped to achieve a partial reversal of those changes. Even though some of the methods described are non-invasive and relatively affordable, still, none of them is the standard for HT diagnosis. CONCLUSION: Each of the methods has its advantages and disadvantages. Photoplethysmography appears to be promising. The method is non-invasive, cheap, does not require experience, and might be synchronized with mobile devices. It is possible that the simplification of the device calibration process and the development of a method allowing for the correct interpretation of the result, regardless of e.g., the patient's skin color, could influence its wider use in the group of HT patients.
... 17 It was considered as a low TcPO2 if the TcPO2 was < 40 mmHg. 18 We adopted an ABI < 0.9 or TBI < 0.75 or TcPO2< 40 mmHg as lower limb arterial ischemia. ...
Background
As an early manifestation of diabetic peripheral neuropathy (DPN), sudomotor dysfunction significantly increases the risk of diabetic foot ulcer. The pathogenesis of sudomotor dysfunction is still unclear. Lower limb ischemia may be related to sudomotor dysfunction, but few studies have explored it. The purpose of this study is to explore the relationship between sudomotor function and comprehensive lower limb arterial ischemia including large arteries, small arteries and microvascular in type 2 diabetes mellitus (T2DM).
Patients and Methods
511 T2DM patients were enrolled in this cross-sectional study. Sudomotor function was assessed qualitatively and quantitatively by Neuropad. Lower limb arterial ischemia was defined as any abnormality of the ankle brachial index (ABI), toe brachial index (TBI) or transcutaneous oxygen tension (TcPO2).
Results
In this study, 75.1% of patients had sudomotor dysfunction. Compared with normal sudomotor function, patients with sudomotor dysfunction had a higher incidence of lower limb arterial ischemia (51.2% vs 36.2%, p = 0.004). Similarly, compared with the non-arterial ischemia group, the proportion of sudomotor disorders was higher in the arterial ischemia group (p = 0.004). Low TBI and low TcPO2 groups also had a higher proportion of sudomotor disorders (all p < 0.05).Compare with normal groups, low ABI, low TBI, and low TcPO2 groups had lower Slop4 which quantitatively reflecting Neuropad discoloration. Arterial ischemia was an independent risk factor for sudomotor dysfunction [OR = 1.754, p = 0.024]. Low TcPO2 also independently increased the risk of sudomotor disorders [OR = 2.231, p = 0.026].
Conclusion
Lower limb arterial ischemia is an independent risk factor of sudomotor dysfunction. Especially below the ankle (BTA) small arteries and microvascular ischemia may also be involved in the occurrence of sudomotor disorders.
... El sistema de información manual limita el proceso de seguimiento y evaluación a la GPC. Recomendaciones 7,13,25,27,28,[31][32]41,43 El proceso sistemático de seguimiento y evaluación de la implementación de la GPC -Amputados requiere el desarrollo de la aplicación de la historia clínica electrónica en IPS de tercer nivel de atención que es donde se aplicará la mayor parte de las recomendaciones. ...
Guía para profesionales de la salud 2015. Guía No. 55 para el diagnóstico y tratamiento preoperatorio, intraoperatorio y postoperatorio de la persona amputada, la prescripción de la prótesis y la rehabilitación integral
... Because transcutaneous testing is frequently used to screen patients for hyperbaric oxygen (HBO) therapy, measurements may be performed in the hyperbaric chamber at treatment pressure. Diabetic patients whose TcPO 2 values during a hyperbaric session are >200 mmHg have a significant likelihood of benefitting from HBO therapy, whereas patients whose "in-chamber" TcPO 2 values are <50mmHg are not likely to benefit [28][29][30][31]. ...
Diabetic foot ulceration is a major complication of diabetes.If untreated, diabetic foot ulcers may become infected and require total or partial amputation of the affected limb. In this Chapter, we briefly overview the pathophysiology of diabetic foot, including microbial burden, current “gold standard” diagnostics, prediction of development, and novel screening optical modalities, which have been translated into the clinic but have not yet received widespread clinical adoption.
We focus on diagnostics methods already being used (current methods) or with the potential to be used (novel optical methods) by primary care practitioners for screening purposes. Efficient screening modalities allow earlier interventions in a patient population that already presents clinically with late-stage complications, significant morbidity, and mortality risk.
... Ankle brachial index (ABI) and transcutaneous oxygen pressure (TcPO2) were measured by arteriosclerosis diagnostic instrument and transcutaneous oxygen pressure detector respectively. ABI < 0.9 and/or TcPO2 < 40 mmHg suggested diabetic peripheral vascular disease (DPVD) (22,23). Diabetic distal symmetric polyneuropathy (DSPN) was diagnosed by measuring ankle reflex, acupuncture pain perception, vibration perception, pressure perception, and temperature perception according to the Chinese guideline for the prevention and treatment of type 2 diabetes mellitus (2017 edition) (24). ...
Introduction
This study aimed to explore the novel classification of inpatients with new-onset diabetes in Eastern China by the cluster-based classification method and compare the clinical characteristics among the different subgroups.
Methods
A total of 1017 Inpatients with new-onset diabetes of five hospitals in Eastern China were included in the study. Clustering analysis was used to cluster the data into five subgroups according to six basic variables. The differences in clinical characteristics, treatments, and the prevalence of diabetes-related diseases among the five subgroups were analyzed by multiple groups comparisons and pairwise comparisons. The risk of diabetes-related diseases in the five subgroups was compared by calculating odd ratio (OR). P value < 0.05 was considered significant.
Results
Five subgroups were obtained by clustering analysis with the highest proportion of patients with severe insulin-deficient diabetes (SIDD) 451 (44.35%), followed by patients with mild age-related diabetes (MARD) 236 (23.21%), patients with mild obesity-related diabetes (MOD) 207 (20.35%), patients with severe insulin-resistant diabetes (SIRD) 81 (7.96%), and patients with severe autoimmune diabetes (SAID) 42 (4.13%). Five subtypes had their own unique characteristics and treatments. The prevalence and risk of diabetes-related complications and comorbidities were also significantly different among the five subtypes. Diabetic kidney disease (DKD) was the most common in SIRD group. Patients in SIDD, SIRD, and MARD groups were more likely to develop cardiovascular disease (CVD) and/or stroke, diabetic peripheral vascular disease (DPVD), and diabetic distal symmetric polyneuropathy (DSPN). The prevalence and risk of metabolic syndrome (MS) were the highest in MOD and SIRD groups. Patients in SAID group had the highest prevalence and risk of diabetic ketoacidosis (DKA). Patients with MOD were more likely to develop non-alcoholic fatty liver disease (NAFLD).
Conclusions
The inpatients with new-onset diabetes in Eastern China had the unique clustering distribution. The clinical characteristics, treatments, and diabetes-related complications and comorbidities of the five subgroups were different, which may provide the basis for precise treatments of diabetes.
... For these reasons, not all patients in this group can be verified as CLTI. This may be one of the reasons that no statistical differences were found in TcPO 2 between the three groups [27]. However, the heterogeneity in this group is a relevant reflection of daily clinical practice. ...
Background:
In this study, we assessed the ability of the EPOS system (Perimed AB, Järfälla, Stockholm, Sweden) to detect differences in tissue perfusion between healthy volunteers and patients with peripheral arterial disease (PAD) with different severity of disease.
Methods:
This single-center prospective pilot study included 10 healthy volunteers and 20 patients with PAD scheduled for endovascular therapy (EVT). EPOS measurements were performed at rest at 32 °C and 44 °C, followed by transcutaneous oxygen pressure (TcPo2) measurements. The measurements were performed on the dorsal and medial side of the foot, as well as the lateral side of the calf. EPOS parameters included hemoglobin oxygen saturation (HbSo2) and speed-resolved red blood cell (RBC) perfusion.
Results:
HbSo2 at 44 °C was significantly different between the three groups for all measurement locations. The overall speed-resolved RBC perfusion at 44 °C was statistically significant between the groups on the dorsal and medial side of the foot but not on the calf. TcPo2 values were not significantly different between the three groups.
Conclusions:
This study demonstrates that the EPOS system can depict differences in tissue perfusion between healthy volunteers, patients with Fontaine class IIb PAD, and those with Fontaine class III or IV PAD but only after heating to 44 °C.
... A normal healthy value in the foot is > 50 mmHg. A value of < 40 mmHg is thought to represent sufficient hypoxia to impair wound healing[36]. According to International Working Group on the Diabetic Foot[IWDGF] guidelines of 2019, in a result < 25 mmHg, urgent vascular imaging should be considered together with revascularization[1]. ...
... The influence of these provocation tests on tissue oxygenation may be assessed with transcutaneous oxygen pressure (tcPO 2 ) measurements, which also allow for simultaneous functional evaluation of skin microcirculation. In recent years, the practical value of tcPO 2 in screening and follow up of overt vascular disease has been well documented [10][11][12][13][14][15][16]. TcPO 2 values have been also confirmed as an independent prognostic marker for 1-year mortality among patients with type 1 diabetes and diabetic foot ulcers [17]. ...
Introduction:
Transcutaneous oxygen pressure (tcPO2) is a non-invasive method of measuring skin oxygenation that may reflect its superficial perfusion. Skin microvasculature may be impaired in patients with late onset of type 1 diabetes (DM1). However, its condition in children has not been fully determined.
Aim:
To compare tcPO2 in children with short-lasting non-complicated DM1 and age-matched healthy controls with regard to concomitant vascular risk factors.
Material and methods:
The study group consisted of 51 paediatric patients aged 14.9 (8.4-18.0) years with short-lasting DM1 without clinical evidence of diabetic micro- or macroangiopathy and 28 control subjects aged 14.8 (11.3-17.7) years. TcPO2 was tested prior, during and after applying post-occlusive reactive hyperaemia (PORH) test in standardized conditions. Biochemical parameters were assessed and then compared between the groups.
Results:
TcPO2 at maximal ischemia during PORH was higher in the DM1 patients than in healthy controls (2.4 (0.7-18.8) vs. 1.6 (0.4-12.0), p = 0.002). No differences were found regarding the tcPO2 measurements recorded prior to ischemia or after recovery. In DM1, concentrations of total cholesterol, triglycerides, HbA1c and TSH were significantly higher than in healthy controls. The fT4 levels were significantly lower in the DM1 group. After adjusting for lipid levels, no differences in tcPO2 were found, and a multivariate analysis showed the cholesterol levels have a significant impact on tcPO2 response to maximal ischemia.
Conclusions:
Our results indicate that increased lipid levels are responsible for the impaired skin response to ischemic stimuli in short-lasting DM1. This supports the importance of aggressive lipid control in prevention of early onset microangiopathy in those patients.
... Exogenous hypoxia marker pimonidazole (Hypoxyprobe™) as well as endogenous hypoxia surrogate markers such as HIF-1α and carbonic anhydrase 9 (CA-IX) are neither quantitative nor repeatable over time [15]. Transcutaneous oximetry (TcO 2 ) is limited to superficial tissue (diabetic ulcers) and requires heating of tissue to induce diffusion of oxygen [16]. Electron paramagnetic resonance (EPR) oximetry is an innovative technology which enables repeatable, reliable, non-invasive tissue oxygen measurements using paramagnetic materials, such as carbon black in India ink, char, and lithium phthalocyanine (LiPc), as oxygen probes [17][18][19]. ...
The objective of this study is to describe the oxygen profile obtained by electron paramagnetic resonance (EPR) oximetry of tissue after radiation, surgery, and hyperbaric oxygen therapy (HBOT) and its relationship to wound healing in a rodent model. The study design is rodent model for wound healing. A rodent model for wound healing was used for oxygen measurements before and after various treatments. EPR measurements and biopsies of normal vs irradiated and flap vs non-flap tissues were taken at 1–3-week intervals for 12 weeks. Wound healing was evaluated by gross photos, histology, and immunostaining. Student’s t test and a linear mixed model were used to compare oxygen levels and gross healing with radiation exposure. A Proportional Odds model was also used to calculate odds ratio toward better wound-healing rate with radiation exposure. In the rodent model, at 1–3 weeks after irradiation, the mean tissue oxygen measurement was significantly lower in irradiated versus non-irradiated leg tissue. There was a significant difference in oxygenation between flap and non-flap tissue in an irradiated bed at 1 and 3 weeks after surgery. On gross evaluation, wound healing from z-plasty flap was significantly worse in irradiated tissue compared to non-irradiated tissue. A rodent model for wound healing showed that radiation resulted in decreased tissue oxygenation at 1–3 weeks after irradiation. Wound healing was compromised in irradiated tissue at earlier time points when tissue oxygenation was lower. Oxygen profiling with EPR oximetry can be used to identify timing of oxygen interventions to improve wound healing. Level of evidence is NA, animal studies.
... Transcutaneous oximetry (TcPO2) and segmental perfusion pressure (SPP) measurements may be useful in such settings. 43 Commonly performed with ABI or SPP testing, pulse volume recordings acquire qualitative assessments of arterial flow in the limb whose appearance is similar to Doppler wave forms and can be used to supplement the pressure measurements of the ABI or SPP, particularly in the setting of arterial calcification. Doppler ultrasonographic evaluation can also provide audible pulse wave assessment from the normal multiphasic to the monophasic or absent arterial flow. ...
Effective revascularization of the patient with peripheral artery disease is about more than the procedure. The approach to the patient with symptom-limiting intermittent claudication or limb-threatening ischemia begins with understanding the population at risk and variation in clinical presentation. The urgency of revascularization varies significantly by presentation; from patients with intermittent claudication who should undergo structured exercise rehabilitation before revascularization (if needed) to those with acute limb ischemia, a medical emergency, who require revascularization within hours. Recent years have seen the rapid development of new tools including wires, catheters, drug-eluting technology, specialized balloons, and biomimetic stents. Open surgical bypass remains an important option for those with advanced disease. The strategy and techniques employed vary by clinical presentation, lesion location, and lesion severity. There is limited level 1 evidence to guide practice, but factors that determine technical success and anatomic durability are largely understood and incorporated into decision-making. Following revascularization, medical therapy to reduce adverse limb outcomes and a surveillance plan should be put in place. There are many hurdles to overcome to improve the efficacy of lower extremity revascularization, such as restenosis, calcification, microvascular disease, silent embolization, and tools for perfusion assessment. This review highlights the current state of revascularization in peripheral artery disease with an eye toward technologies at the cusp, which may significantly impact current practice.
... Our finding, supported by a multifactorial statistical analysis (see Section 3), is at variance with certain data that reportedly assign to TcPO 2 a predictive value for wound healing.48,49 In actual fact, however, the literature is quite discordant on this point, with other data negating any role of TcPO 2 as a marker for wound healing50,51 or even seeing in this variable a correlate of healing failure.52,53 These inconsistencies may not be that surprising in view of the diversity of conditions employed for recording TcPO 2 . ...
The aim of this study is to ascertain whether the simultaneous measurement of hemoglobin O2 saturation (StO2) and dimension of venous leg ulcers (VLU) by Near Infrared Spectroscopy (NIRS) imaging can predict the healing course with protocols employing a conventional treatment alone or in combination with Hyperbaric Oxygen Therapy (HBOT). NIRS 2D images of wound region were obtained in 81 patients with hard‐to‐heal VLU that had been assigned, in a randomized controlled clinical trial, to the following protocols: 30 HBOT sessions, adjunctive to the conventional therapy, either twice daily over three weeks (Group A) or once daily over six weeks (Group B), and conventional therapy without HBOT (Group C). Seventy‐three patients completed the study with a total of 511 NIRS images being analyzed. At the end of treatment, wound area was significantly smaller in all three groups. However, at the 3‐week mark the wound area reduction tended to be less evident in Group A than in the other groups. This trend continued up to the 6‐week end‐point when a significantly greater area reduction was found with Group B (65.5%) and Group C (56.8%) compared to Group A (29.7%) (p<0.01). Furthermore, a higher incidence of complete healing was noted with Group B (20%) than with Group A (4.5%) and Group C (3.8%). When using a final wound reduction in excess of 40% to distinguish healing from non‐healing ulcers, it was found that only the former present NIRS StO2 values abating over the study period both at center and edge of lesions.
In conclusion, NIRS analysis of StO2 and wound area can predict the healing course of VLU. Adjunctive HBOT significantly facilitates VLU healing compared to the conventional treatment alone. This positive action, however, becomes manifest only with a longer and less intensive treatment schedule.
One-half of the estimated 1.2 million new cases of invasive cancer will receive radiation therapy as a part of their cancer treatment and despite best efforts, 5% of patients will develop severe reactions to radiation therapy. These effects cause significant morbidity which may occur months or years after treatment. Management is often difficult and unsatisfactory. Hyperbaric oxygen is shown to have beneficial effects in all the three mechanisms known to cause the morbidity in irradiated tissues: HBO2 stimulates angiogenesis and secondarily improves tissue oxygenation; it reduces fibrosis; and it mobilizes and induces an increase of stem cells within irradiated tissues. Hyperbaric oxygen therapy is a treatment in which patients breathe 100% oxygen while inside a pressurized hyperbaric chamber. HBO treatment regimens consist of 1.5 to 2 hours per treatment for 20 to 40 treatments, and up to 60 treatments if needed. Evidence demonstrated that Hyperbaric Oxygen is safe and does not accelerate malignant growth or cause a dormant malignancy to be reactivated. Hyperbaric oxygen helps reduce morbidity, disfiguring sequelae and further need for corrective surgery. It is a cost-effective treatment for reducing mortality and morbidity in patients with radiation-induced wounds in any area or organ of the body and should be used as an adjunct to standard line of treatment with antibiotics and surgical debridement’s.
Transcutaneous oximetry is the technique to monitor the local oxygen tension in the peri-wound region to ensure the effectiveness of hyperbaric treatment. Wound hypoxia hampers the healing process in case of problem wounds and the measurement of transcutaneous oxygen tension by administering 100% oxygen under normobaric conditions helps the physician to decide the course of hyperbaric oxygen therapy. It is especially beneficial to monitor the transcutaneous oxygen levels in case of treatment of wound healing where local oxygen tension in wounds determines the effectiveness of wound healing under hyperbaric conditions.
Diabetics develop foot ulcers due to peripheral ischaemia, neuropathy, or nero-ischaemia both. With rising prevalence of peripheral arterial occlusive disease (PAOD), it is considered the most important factor in development of foot ulcer and may subsequently lead to leg amputation among them. Various modalities available to assess the severity of vasculopathy among diabetic patients include measurement of Ankle Brachial Pressure Index (ABI), Toe Brachial Pressure Index (TBI), and Trans-cutaneous Partial pressure of Oxygen (TcPO2). Though, each modality, mentioned above, can predict the limb outcome (ulcer healing/ minor or major amputations) independently, but their predictive abilities are variable in various studies. This was a cross-sectional, observational study conducted over 100 patients with 108 diabetic feet, which has compared the accuracy of ABI, TBI, and TcPO2 in predicting limb outcome among patients with vasculopathy associated foot ulcers among diabetics. Patients who underwent major and minor amputations had mean ABI of 0.54 ± 0.22 and 0.85 ± 0.19, mean TBI of 0.25 ± 0.12 and 0.42 ± 0.26, and mean TcPO2 of 27.08 ± 11.88 and 41.29 ± 22.56 respectively. Out of three modalities, TcPO2 had the maximum predictive ability (AUC — 0.865009) for amputation followed by TBI (AUC — 0.825865). In patients with vaculopathy associated DFUs, TcPO2 is a better predictor of limb outcome when compared to TBI and ABI.
Diabetic foot ulcers (DFUs) affect one in every three people with diabetes. Imaging plays a vital role in objectively complementing the gold-standard visual yet subjective clinical assessments of DFUs during the wound treatment process. Herein, an overview of the various imaging techniques used to image DFUs is summarized. Conventional imaging modalities (e.g., computed tomography, magnetic resonance imaging, positron emission tomography, single-photon emitted computed tomography, and ultrasound) are used to diagnose infections, impact on the bones, foot deformities, and blood flow in patients with DFUs. Transcutaneous oximetry is a gold standard to assess perfusion in DFU cases with vascular issues. For a wound to heal, an adequate oxygen supply is needed to facilitate reparative processes. Several optical imaging modalities can assess tissue oxygenation changes in and around the wounds apart from perfusion measurements. These include hyperspectral imaging, multispectral imaging, diffuse reflectance spectroscopy, near-infrared (NIR) spectroscopy, laser Doppler flowmetry or imaging, and spatial frequency domain imaging. While perfusion measurements are dynamically monitored at point locations, tissue oxygenation measurements are static two-dimensional spatial maps. Recently, we developed a spatio-temporal NIR-based tissue oxygenation imaging approach to map for the extent of asynchrony in the oxygenation flow patterns in and around DFUs. Researchers also measure other parameters such as thermal maps, bacterial infections (from fluorescence maps), pH, collagen, and trans-epidermal water loss to assess DFUs. A future direction for DFU imaging would ideally be a low-cost, portable, multi-modal imaging platform that can provide a visual and physiological assessment of wounds for comprehensive wound care intervention and management.
Objective
TcPO2 is a non-invasive, non-radiological test to measure local oxygen released from capillaries through the skin. Since it reflects the metabolic state of the lower limb, it can predict wound healing in patients with critical limb threatening ischemia (CLTI). The purpose of this study was to determine the effectiveness of TcPO2 test in evaluating wound healing potential of patients with CLTI.
Design
This was a retrospective, single-center, non-randomized, and observational study.
Methods
A prospectively registered database of patients who visited Vascular Surgery Department of St. Mary’s Hospital for CLTI and underwent TcPO2 tests from October 1, 2015 to July 1, 2021 was reviewed. Patients were divided into two groups: 1) those who had amputation only; and 2) those who underwent revascularization procedures. Patients whose wound healing status could not be determined were excluded. Clinical characteristics of patients, patient characteristics related to lower TcPO2 value, treatment success rate, and time for the wound to be healed were analyzed.
Results
A total of 84 patients were included in this study. There was no difference in background patient characteristics between the two groups despite better survival within 12 months and shorter healing time in the revascularization group. A total of 76 patients survived 12 months after surgery and 63 patients were healed. Higher HbA1c, higher serum creatinine, history of stroke, and history of coronary artery disease were related to lower TcPO2 value on multiple linear regression. The cutoff value of TcPO2 was determined to be 40 mmHg for predicting wound healing. This value was similar to those of previous studies. In addition, there was a negative correlation between TcPO2 and wound healing time. Correlations among ABI, TBI, and TcPO2 were not determined because ABI and TBI for some patients could not be obtained due to wound condition.
Conclusion
TcPO2 value can predict the wound healing process of ischemic lower extremity injury.
Hyperbaric oxygen (HBO2) has been used as an adjunctive treatment for the care of advanced non‐healing diabetic foot ulcers (DFUs). A patient's in‐chamber transcutaneous oximetry measurement (TCOM) is currently the most effective predictor for response to HBO2 therapy but still excludes close to 1 in 4 patients who would benefit out of treatment groups when used for patient selection. Improving selection tools and criteria could potentially help better demonstrate HBO2 therapy's efficacy for such patients. We sought to identify if long‐wave infrared thermography (LWIT) measurements held any correlation with a patient's TCOM measurements and if LWIT could be used in a response prediction role for adjunctive HBO2 therapy. To investigate, 24 patients already receiving TCOM measurements were enrolled to simultaneously be imaged with LWIT. LWIT measurements were taken throughout each patient's therapeutic course whether they underwent only standard wound care or adjunctive HBO2 treatments. A significant correlation was found between in‐chamber TCOM and post‐HBO2 LWIT. There was also a significant difference in the post‐HBO2 LWIT measurement from 1st treatment to 6 weeks or last treatment recorded. These initial findings are important as they indicate a possible clinical use for LWIT in the selection process for patients for HBO2 therapy. Larger studies should be carried out to further articulate the clinical use of LWIT in this capacity. This article is protected by copyright. All rights reserved.
Revascularization plays an important role in the treatment of chronic limb-threatening ischemia. Evaluation of hemodynamic compromise in the lower extremity is required to optimize the treatment strategy for each patient. A variety of methods have been reported to detect arterial obstruction or impaired foot perfusion. This article reviews each method, clarifying features and limitations.
Major amputation is unavoidable if revascularization is not possible in critical limb ischemia with nonviable limb. Good perfusion is imperative to achieve uneventful wound healing. This case series analysis evaluated the use of laser Doppler flowmeter and tissue spectrometer (O2C®) in assessing tissue perfusion before and after a major lower limb amputation. Forty patients with an indication for a major lower limb amputation were from March 2018 to January 2020 recruited. O2C® measurement was performed at pre-defined points along the transection line and at pre-designated points of reference before and after surgery. Analysis of variance was carried out for repeated measurements. The correlation of three different O2C® parameters with wound healing was analyzed. After exclusion of 3 patients, 37 patients remained for evaluation. Twenty-three patients (62%) had uneventful wound healing, 9 patients (24%) had a minor healing disorder, whereas 5 patients (14%) needed surgical re-intervention. Few correlations between the O2C® parameters and wound healing could be demonstrated. These included the preoperative oxygen saturation in the thigh area before a thigh amputation (p = 0.0157). The blood flow rate correlated with wound healing on the thigh preoperatively during knee disarticulation (p = 0.0349). Marked variability in the measured values over various points in time was noted. With the exception of the oxygen saturation and flow parameter on the thigh, none of the other O2C measurements predicted wound healing after a major lower limb amputation. O2C® is of minor value to assess tissue perfusion before a major limb amputation.
Peripheral arterial disease is an atherosclerotic occlusive disease primarily of the lower extremities with a wide variety of clinical presentations ranging from asymptomatic disease to tissue loss which threatens the viability of affected limbs. The epidemiology, risk factors, and clinical presentations of this widespread disease highlight its ever-increasing impact on patients worldwide. This reinforces the need for further investigation to better comprehend the pathophysiologic mechanisms and biological hurdles which make its treatment challenging. Although modern vascular practice incorporates a multimodal regimen of medical management and surgical (open and endovascular) techniques to improve blood flow to the extremities and extend the viability of threatened limbs, there is significant room for further research to improve long-term outcomes and quality of life for these medically complex patients.
Introduction:
Measurement of skin temperature with infrared thermometry has been utilised for assessing metabolic activity and may be useful in identifying patients with ulcers suitable for hyperbaric oxygen treatment and monitoring their treatment progress. Since oxygen promotes vasoconstriction in the peripheral circulation, we hypothesised that oxygen administration may lower skin temperature and complicate the interpretation of temperatures obtained. This pilot study investigated the effect of oxygen administration on lower limb skin temperature in healthy subjects and diabetic patients.
Methods:
Volunteers were recruited from healthy staff members (n = 10) and from patients with diabetic foot ulcers (n = 10) at our facility. Foot skin surface temperatures were measured by infra-red thermometry while breathing three different concentrations of oxygen (21%, 50% and 100%).
Results:
Skin temperature changes were observed with increasing partial pressure of oxygen in both groups. The mean (SD) foot temperatures of diabetic patients and healthy controls at air-breathing baseline were 30.1°C (3.6) versus 29.0°C (3.7) respectively, at FiO₂ 0.5 were 30.1°C (3.6) versus 28.5°C (4.1) and at FiO₂ 1.0 were 28.3°C (3.2) versus 29.2°C (4.3). None of these differences between groups were statistically significant.
Conclusions:
Data from this small study may indicate a difference in thermal responses between healthy subjects and diabetic patients when inhaling oxygen; however, none of the results were statistically significant. Further investigations on a larger scale are warranted in order to draw firm conclusions.
Critical limb ischemia is a clinical syndrome of ischemic pain at rest or tissue loss resulting from non-healing ulcers or gangrene related to peripheral artery disease. The primary therapeutic goal is to preserve limb function. The most important factor for determining the healing potential of a wound is the degree of perfusion to the affected segment. Several tests objectively measure the degree of tissue perfusion: for example, ankle-brachial index, toe pressure, ultrasound, transcutaneous oxygen pressure, two-dimensional perfusion angiography, indocyanine green angiography, diagnostic nuclear medicine imaging, and laser doppler skin perfusion pressure. In this study, we investigated tests that can measure tissue perfusion and discussed the advantages and limitations of each test.
Peripheral artery disease (PAD) is a flow-limiting condition caused by narrowing of the peripheral arteries typically due to atherosclerosis. It affects almost 200 million people globally with patients either being asymptomatic or presenting with claudication or critical or acute limb ischemia. PAD-affected patients display increased mortality rates, rendering their management critical. Endovascular interventions have proven crucial in PAD treatment and decreasing mortality and have significantly increased over the past years. However, for the functional assessment of the outcomes of revascularization procedures for the treatment of PAD, the same tests that have been used over the past decades are still being employed. Those only allow an indirect evaluation, while an objective quantification of limb perfusion is not feasible. Standard intraarterial angiography only demonstrates post-intervention vessel patency, hence is unable to accurately estimate actual limb perfusion and is incapable of quantifying treatment outcome. Therefore, there is a significant necessity for real-time objectively measurable procedural outcomes of limb perfusion that will allow vascular experts to intraoperatively quantify and assess outcomes, thus optimizing treatment, obviating misinterpretation, and providing significantly improved clinical results. The purpose of this review is to familiarize readers with the currently available perfusion-assessment methods and to evaluate possible prospects.
Objective
The aim of this study was to evaluate changes in transcutaneous oxygen pressure (tcpO2) and systolic toe pressure (TP) during endovascular intervention.
Methods
This was a single centre prospective, non-randomised, observational feasibility study. Patients with chronic limb threatening ischaemia (CLTI) due to infrainguinal disease scheduled for endovascular treatment were included between March 2018 and December 2019. TcpO2 was measured continuously bilaterally at foot level throughout the procedure and at follow up. Specific time points during the intervention were chosen for comparison to baseline (before arterial puncture): average tcpO2 level five minutes prior to percutaneous transluminal angioplasty (PTA); 10 minutes after PTA; and at completion. Bilateral TP was recorded using laser Doppler flowmetry before arterial puncture, at completion, and at clinical follow up. Angiograms were analysed for successful revascularisation and vascular lesions classified according to the Global Limb Anatomical Scoring System (GLASS). Rutherford and WIfI (Wound, Ischaemia, and foot Infection) classifications were registered, as well as clinical outcome.
Results
Twenty-one patients completed the study. Completion angiograms showed inline flow to the foot in all but two patients. Median time to follow up was 10 weeks (range 8 – 13 weeks) and all patients except one improved clinically. TcpO2 decreased during the initial stage of the intervention, from before arterial puncture to five minute average before PTA (p < .001) and did not recover to above baseline values at the end of intervention. TcpO2 increased significantly at follow up (p < .001). TP increased statistically significantly during intervention (p < .001) and at follow up (p < .001) compared with baseline.
Conclusion
TcpO2 and TP measurements are safe and feasible non-invasive techniques for haemodynamic monitoring during endovascular revascularisation. TP increased significantly immediately after completion of the successful intervention, whereas tcpO2 did not. Both TP and tcpO2 demonstrated a significant increase at the 10 week follow up.
Introduction
The sympathetic nervous system (SNS) is important in regulation of perfusion. Dorsal root ganglion stimulation (DRG-S) modulates sympathetic tone and is approved to treat complex regional pain syndrome, a disorder related to SNS dysfunction. We herein present 3 cases of DRG-S therapy to improve blood flow and symptoms of ischemia in peripheral arterial disease (PAD).
Methods
Patient 1 is a 44-year-old female with dry gangrene of the third and fourth digits of her right hand due to Raynaud's syndrome who was scheduled for amputation of the affected digits. DRG-S leads were placed at the right C6, 7, and 8 DRGs. Pulse volume recordings (PVR) were measured at baseline and with DRG-S. Patient 2 is a 55-year-old female with a non-healing ulcer of her left foot secondary to PAD scheduled for a below the knee amputation who underwent a DRG-S trial with leads placed at the left L4 and L5 DRGs followed by a spinal cord stimulation trial with leads placed at T9-T10 for comparison. Transcutaneous oximetry (TcPO2) was measured at baseline and after 3 days of each therapy. Patient 3 is a 69-year-old female with persistent left foot pain at rest secondary to PAD with DRG-S leads placed at the left L4 and S1 level.
Results
All 3 patients experienced a significant reduction in pain with DRG-S, along with improvements in blood flow of the involved extremities, avoiding or limiting amputation. PVR improved dramatically with DRG-S in patient 1. A greater improvement in TcPO2 was seen with the DRG-S trial compared to spinal cord stimulation trial in patient 2. Patient 3 experienced an increase in walking distance and demonstrated long term efficacy and limb salvage at 32 months post implantation.
Conclusion
Modulation of SNS output from DRG-S through orthodromic and antidromic autonomic pathways is likely responsible for improving blood flow. DRG-S may be a treatment option for PAD.
Angiosome-directed endovascular therapy for the treatment of chronic limb-threat ischemia (CLTI) remains controversial due to overlap of wound angiosomes. Angiographic grading of success has limitations and translesional pressure assessments are seldom performed in the infrapopliteal vessels. Objective criteria to determine revascularization success in tibiopedal vessels have not been well described. Quantifying perfusion to a wound bed after establishing direct or indirect (via collateral) flow after revascularization is an important component for treating CLTI patients yet is seldom performed. We report the use of fluorescent angiography (FA) to quantitatively examine perfusion of a diabetic foot ulcer before and after angiosome-directed endovascular therapy.
Diabetic foot complications are the main cause of non-traumatic lower limb amputation internationally. Most amputations in diabetes are preceded by foot ulceration. Therefore, a thorough understanding of the causes, assessment and management of ulceration is essential. This chapter provides a concise description of the key factors contributing to the pathophysiology of the diabetic foot. The chapter also outlines an evidence-based approach to the clinical assessment and management based on recently published guidelines.
Background: Oxygen is mandatory for almost all wound healing processes, in particular the processes of cell regeneration and angiogenesis. As it is lacking in chronic and even acute wounds, oxygen substitution seems to be an obvious adjuvant tool. In vitro and in vivo tests showed improvement of microenvironment essential for the onset of appropriate healing processes.
Introduction:
Delayed wound healing indicates wounds that have failed to respond to more than 4-6 weeks of comprehensive wound care. Wounds with delayed healing are a major source of morbidity and a major cost to hospital and community healthcare providers. Hyperbaric oxygen therapy (HBOT) is a treatment designed to increase the supply of oxygen to wounds and has been applied to a variety of wound types. This article reviews the place of HBOT in the treatment of non-healing vasculitic, calcific uremic arteriolopathy (CUA), livedoid vasculopathy (LV), pyoderma gangrenosum (PG) ulcers.
Methods:
We searched electronic databases for research and review studies focused on HBOT for the treatment of delayed healing ulcers with rare etiologies. We excluded HBOT for ulcers reviewed elsewhere.
Results:
We included a total of three case series and four case reports including 63 participants. Most were related to severe, non-healing ulcers in patients with vasculitis, CUA, LV, and PG. There was some evidence that HBOT may improve the healing rate of wounds by increasing nitric oxide (NO) levels and the number of endothelial progenitor cells in the wounds. HBOT may also improve pain in these ulcers.
Conclusion:
We recommend the establishment of comprehensive and detailed wound care registries to rapidly collect prospective data on the use of HBOT for these problem wounds. There is a strong case for appropriately powered, multi-centre randomized trials to establish the true efficacy and cost-effectiveness of HBOT especially for vasculitis ulcers that have not improved following immunosuppressive therapy.
The measurement of partial oxygen pressure in arterial blood by use of transcutaneous pulse oximetry (tcPo2) is a technique relatively new to clinical practice. However, there are notable differences of values both in healthy and arteriopathic subjects, depending on which part of the limb the measurement is carried out. The authors define a cutaneous reference map for oximetric measurements in both healthy and arteriopathic subjects. In a group of 200 healthy subjects and a group of 82 subjects affected by obliterative arteriopathy of the lower limbs at the second Fontaine stage, oximetric measurements were carried out under rest conditions. By comparing the oximetric ranges at all examined levels, it can be seen that there is a wide band of overlap between the minimum values of healthy subjects and those of the arteriopathic subjects.
In a group of 30 healthy subjects and in a group of 30 subjects affected by obliterative arteriopathy of the lower limbs at the second Fontaine stage, oximetric measurements were taken at I, II, III back levels of the leg during maximal treadmill test. In this case, by comparing the oximetric ranges between the two groups, it can be seen that all arteriopathic subjects present significantly lower values as compared with those of the healthy subjects at each examined level. This permits a confident diagnosis of pathology.
The authors conclude that in order to make a correct diagnosis of arteriopathy by using transcutaneous oximetry, it is necessary to consider both the measurements carried out under rest conditions and those carried out during maximal treadmill test.
Introduction: Transcutaneous oximetry measurement (TCOM) is the process of measuring the partial pressure of tissue oxygen (PtcO2) via a heated electrode placed upon the skin. Aim: We aim to describe the use of TCOM to define tissue hypoxia and normal ranges for PtcO2, and correlate TCOM with clinical outcomes for wounds treated with hyperbaric oxygen therapy (HBOT). Methods: A structured literature search covering the past 25 years was performed using the MeSH terms: blood gas monitoring; transcutaneous; wound healing; peripheral vascular disease; diabetes; and hyperbaric oxygenation. We critically appraised all relevant papers and, using our synthesis of the data, present our recommendations for the use of TCOM in the assessment of problem wounds for HBOT, and for further research. Results: Normal chest PtcO2 is 60-70 mmHg, which is similar to limb values. TCOM values do not change significantly with age in healthy individuals but limb values are reduced in diabetes, peripheral vascular disease and in limb elevation. TCOM has been validated in predicting wound healing, and successful vascular reconstruction and amputation level, as well as in confirmation of the need for amputation. TCOM is a more effective marker of disease than Doppler assessment or ankle-brachial indices. Thirty-eight studies since 1982 suggest that hypoxia is defined as PtcO2 = 10-40 mmHg. A single critical value for tissue viability has not been determined. PtcO2 increases with increasing partial pressure of inspired oxygen (Pt O2), and is markedly elevated during HBOT. TCOM values progressively increase during a course of HBOT. While low PtcO2 values breathing air confirm wound hypoxia, they do not predict outcome with HBOT. Breathing 100% oxygen at ambient pressure is somewhat predictive of outcome - if wound PtcO2 < 35 mmHg, 41% fail to heal; while a PtcO2 > 200 mmHg breathing hyperbaric oxygen is the best single discriminator between success and failure of HBOT (74% reliable). Using the available data, we suggest clinical guidelines. Conclusions: TCOM is useful to identify patients with problem wounds who may respond to HBOT. Poor quality of the available clinical studies limits the interpretation of the available evidence. A large, multicentre prospective study is required that correlates TCOM using a standard protocol with initial wound grades and clinical outcomes.
In patients with peripheral vascular disease requiring amputation, a below-knee stump is likely to result in improved function compared to above-knee. Unfortunately, clinical assessment of skin circulation is inaccurate, making the decision of amputation level difficult. The transcutaneous oxygen monitor has been investigated as a method of assessing skin circulation. A prospective study using the monitor in 51 amputations based on clinical assessment has shown that a transcutaneous oxygen tension (tcPO2) greater than 40 mm Hg is associated with stump healing, while measurements below that level lead to an unpredictable outcome. Half of the patients undergoing above-knee amputation had a tcPO2 level greater than 40 mm Hg at the below-knee site, suggesting that a successful distal amputation might have been performed. A further prospective study of 50 patients requiring amputation for peripheral gangrene showed that when amputations were performed at the lowest level in the limb with a tcPO2 greater than 40 mm Hg there was a higher rate of below-knee amputations (72%) and a higher rate of successful stump healing. Review of the literature confirms the potential of the monitor as a non-invasive, simple and accurate method of predicting stump healing.
The use of transcutaneous oxygen tension (TCpO2) measurements to objectively and noninvasively diagnose peripheral arterial occlusive disease (PAOD) and to aid in the planning of vascular surgery was investigated. Thirty-two normal subjects and 100 patients with PAOD were studied. TCpO2 values decreased with age; when normalized by measurements on the chest, they did not. Absolute and normalized values of TCpO2 were equally effective in identifying the presence of PAOD and accurately characterized different degrees of severity (claudication vs. rest pain vs. impending gangrene; p less than 0.001). This was true even in diabetic patients, in whom tests based on hemodynamic function were less reliable. Healing of amputations was observed when TCpO2 greater than or equal to 38 mm Hg either preoperatively or after reconstruction; failure to heal in the absence of infection was associated with TCpO2 less than or equal to 38 mm Hg. The need for revascularization was associated with TCpO2 less than 30 mm Hg. A similar distribution of TCpO2 values was associated with success vs. failure of ulcer healing. TCpO2 is a useful complement to standard hemodynamic tests in the diagnosis and management of PAOD and, in addition, provides some distinct advantages.
The utility of transcutaneous oxygen tension measurements in selection of a reliable amputation level was evaluated. Measurements were made at the proposed level of amputation in 37 patients, 22 of whom underwent major limb amputation and in 15 amputation was confined to the forefoot or toes. In patients with successful amputation healing, mean transcutaneous oxygen tension on the anterior skin surface was 50 +/- 8 mm Hg (index 0.79 +/- 0.1 mm Hg). In contrast, patients with failure of healing had a mean transcutaneous oxygen tension of 22 +/- 16 mm Hg (index 0.32 +/- 0.19 mm Hg) (p less than 0.001). Measurements on the posterior or plantar skin surface and posteroanterior differences provided even greater separation between success and failure groups, with no overlap of transcutaneous oxygen tension values or index. Transcutaneous oxygen tension measurement is easily obtained and noninvasive, and can be applied to all patients irrespective of Doppler signals, noncompressible vessels, or painful lesions. Transcutaneous oxygen tension appears to predict successful healing with accuracy, and should be a useful addition to clinical judgment in selection of optimal amputation level.
The use of transcutaneous oxygen tension (TCpO 2 ) measurements to objectively and noninvasively diagnose peripheral arterial occlusive disease (PAOD) and to aid in the planning of vascular surgery was investigated. Thirty-two normal subjects and 100 patients with PAOD were studied. TCpO 2 values decreased with age; when normalized by measurements on the chest, they did not. Absolute and normalized values of TCpO 2 were equally effective in identifying the presence of PAOD and accurately characterized different degrees of severity (claudication vs. rest pain vs. impending gangrene; p < 0.001). This was true even in diabetic patients, in whom tests based on hemodynamic function were less reliable. Healing of amputations was observed when TCpO 2 ≥ 38 mm Hg either preoperatively or after reconstruction; failure to heal in the absence of infection was associated with TCpO 2 ≤ 38 mm Hg. The need for revascularization was associated with TCpO 2 < 30 mm Hg. A similar distribution of TCpO 2 values was associated with success vs. failure of ulcer healing. TCpO 2 is a useful complement to standard hemodynamic tests in the diagnosis and management of PAOD and, in addition, provides some distinct advantages.
To monitor transcutaneous oxygen tension (TcPO2) after percutaneous transluminal angioplasty (PTA) in diabetic patients with ischaemic foot ulcers.
Twenty-three diabetic patients with ischaemic foot ulcers who underwent successful revascularization by PTA (SR group) were retrospectively selected. Twenty diabetic patients who underwent unsuccessful revascularization (UR group) were also included. Transcutaneous oxygen tension was measured at the dorsum of the foot before and 1 (+/- 1), 7 (+/- 1), 14 (+/- 1), 21 (+/- 1) and 28 (+/- 1) days after the surgical procedure.
After PTA, TcPO2 progressively improved in the SR group, reaching its peak 4 weeks after angioplasty. A concomitant decrease of cutaneous carbon dioxide tension (TcPCO2) was also observed immediately after PTA which reached the lowest levels 3 weeks later. In the UR group, TcPO2 showed a slight improvement immediately after PTA but remained stable throughout the observation, while TcPCO2 levels did not change. Finally, the percentage of SR patients with a TcPO2 > or = 30 mmHg was 38.5% 1 week after PTA, while it increased to 75% 3 weeks later.
Transcutaneous oxygen tension monitoring showed that after successful revascularization it takes 3-4 weeks for cutaneous oxygenation to improve and reach the optimal levels for wound healing. Transcutaneous carbon dioxide tension monitoring may be more useful to identify the negative outcome of a revascularization procedure. Our findings suggest that, when the surgical approach can be delayed, the best timing to perform a more aggressive debridement or minor amputations is 3-4 weeks after successful revascularization.
The objective of this retrospective analysis was to determine the reliability of transcutaneous oxygen tension measurement (TcPO2) in predicting outcomes of diabetics who underwent hyperbaric oxygen therapy for lower extremity wounds. Six hyperbaric facilities provided TcPO2 data under several possible conditions: breathing air, breathing oxygen at sea level, and breathing oxygen in the chamber. Overall, 75.6% of the patients improved after hyperbaric oxygen therapy. Baseline sea-level air TcPO2 identified the degree of tissue hypoxia but had little statistical relationship with outcome prediction because some patients healed after hyperbaric oxygen therapy despite very low prehyperbaric TcPO2 values. Breathing oxygen at sea level was unreliable for predicting failure, but 68% reliable for predicting success after hyperbaric oxygen therapy. TcPO2 measured in chamber provides the best single discriminator between success and failure of hyperbaric oxygen therapy using a cutoff score of 200 mmHg. The reliability of in-chamber TcPO2 as an isolated measure was 74% with a positive predictive value of 58%. Better results can be obtained by combining information about sea-level air and in-chamber oxygen. A sea-level air TcPO2 < 15 mmHg combined with an in-chamber TcPO2 < 400 mmHg predicts failure of hyperbaric oxygen therapy with a reliability of 75.8% and a positive predictive value of 73.3%. (WOUND REP REG 2002;10:198–207)
The purpose of this study was to compare the partial pressure of transcutaneous tissue oxygen (TcPO2) in persons with venous ulcers in four positions with and without inspired oxygen.
TcPO2 was evaluated two times, 4 weeks apart at a chest reference and three lower extremity sites.
Lower extremity resting TcPO2 levels were lower in patients with venous ulcers than in healthy adults. Minimal changes in TcPO2 occurred with position changes when subjects breathed room air. When arterial oxygen saturation was increased using inspired oxygen, TcPO2, used as an indicator of perfusion, was lower during leg elevation, sitting, and standing compared to lying supine (p < 0.05).
Control of peripheral circulation and tissue oxygenation may be impaired in persons with venous ulcers. Leg elevation, sitting, and standing decreased wound perfusion and may not be beneficial to individuals with venous insufficiency and ulceration. Research is needed to explore relationships among tissue oxygenation, blood perfusion, compression, positioning, and venous ulcer healing.
Transcutaneous oximetry has been used to define the level of amputation in arteritic patients, with discrepant results. We have studied preoperative statix oximetry in 33 arteritic patients at the Leriche-Fontaine Stage IV, who underwent 36 amputations (thighs = 6, Legs+Symes = 14, transmetatarsal = 7, toes = 9). Oximetry included the measurement, at the level of amputation, of the transcutaneous partial oxygen pressure (tc pO2), of the tissue oxygenation ratio (TOR), preferably with a precordial electrode, of the tc pO2 gain after oxygen inhalation and of the gain ratio with the reference electrode. Two patients died postoperatively, the amputation stump did not heal in another 8 patients. The tc pO2 value was 36.6 +/- 16.2 mm Hg in the healed group and 21.1 +/- 19.9 mm Hg in the non healed group. The TOR respectively was 71.2 +/- 32.7% and 38.6 +/- 29.9% in these two groups. These differences were statistically significant. The difference between the two groups in the measurements made after the oxygenation test was not statistically significant. With a tc pO2 threshold at 26 mm Hg, the sensitivity was 73% and the specificity 75%, the positive predictive value 90%, the negative predictive value 46% and the value of the test 73.5%. The thresholds calculated to be 56% for TOR, 11 mm Hg for the gain and 32% for the gain ratio, did not improve the performances of oximetry. In our study, the tc pO2 was the parameter that best allowed predicting healing was obtained with smaller values than the threshold. Other elements such as the general condition and diabetes have played a role in the prognosis.
Transcutaneous oximetry (tcPO2) performed during either oxygen inhalation or leg dependency was intra-individually compared in 64 patients suffering from a peripheral arterial occlusive disease, with and without critical limb ischemia. Among the 81 extremities investigated, 29 had a moderate peripheral arterial occlusive disease (6 in stage I, 23 in stage II) and 52 were initially affected by rest pain or ulceration (stage III/IV). Thirty-seven legs out of the latter improved under conservative treatment. In the remaining 15 limbs, vascular surgery or an amputation became necessary. The tcPO2 was measured at the forefoot with the patient in supine and sitting positions while breathing room air and in the supine position while inhaling 100% oxygen. In limbs with a tcPO2 below 15 mm Hg of patients in the supine position breathing room air, leg dependency generally provoked larger tcPO2 increases than oxygen inhalation. This difference between oxygen inhalation while supine and room air breathing leg dependency tcPO2 values exhibited an approximately linear correlation with the resting tcPO2. Responses of tcPO2 to leg dependency and oxygen inhalation seemed to reflect different mechanisms, that is, microvascular flow redistribution and supine perfusion reserve, respectively. The best discrimination of critical limb ischemia was observed for the tcPO2 of patients breathing room air while in the supine position, which was not surpassed by either the oxygen inhalation or the leg dependency test. Satisfactory results were achieved by combining limits for, first, supine (10 mm Hg) and sitting (45 mm Hg) tcPO2, as well as, second, ankle arterial pressure (60 mm Hg) and supine tcPO2 (10 mm Hg).
Therapeutic effects of hyperbaric oxygen therapy (HBO) in 50 patients with chronic occlusive arterial diseases were studied with determination of the transcutaneous oxygen pressure (TcPO2), plasma lipid peroxide level, and plasma superoxide dismutase (SOD) level. Necrosis or ulceration was present in 30 patients, rest pain without tissue loss in 6, infection and necrosis in 2, infection of the amputated stump in 2, delayed healing of the amputated stump wound in 8, and delayed union of bone fractures in 2. HBOs were carried out in 2-3 absolute atmospheres for 60 min for 3-40 times (mean, 12.7 times). In combination with HBO, sympathetic denervation was performed in 41 patients, and PGE1 infusions were administered in 46. Of patients with necrosis or ulceration, 16 were healed, 13 were improved, and one was unchanged. Of patients with rest pain, 5 had relief and one was unchanged. All patients with infection were cured. Of patients with delayed healing of amputation wounds, 7 were healed and one required reamputation. All patients with bone fractures obtained bone union. The TcPO2 markedly increased during HBO and remained at a high level for some time after HBO. The lipid peroxide and SOD levels were not changed significantly by HBO.
To identify and quantify risk factors for lower extremity amputation in persons with diabetes mellitus.
Case-control study.
A Veterans Affairs medical center.
Eighty patients having amputation associated with diabetes and 236 diabetic controls without limb lesions were enrolled before surgery from the 21,167 inpatient care and outpatient surgical patients seen at the Seattle Veterans Affairs Medical Center during a 30-month period.
Selected vascular, neuropathic, environmental, health care, self care, nutritional, metabolic, lifestyle, and psychosocial risk factors were measured in all patients before surgery.
Statistically significant risk factors identified from analysis included insufficient mean below-knee and foot cutaneous circulation (odds ratio, 161; 95% CI, 55.1 to 469); ankle-arm blood pressure index less than 0.45 (odds ratio, 55.8; CI, 14.9 to 209); absence of lower leg vibratory perception (odds ratio, 15.5; CI, 8.3 to 28.7); low levels of high-density lipoprotein (HDL) subfraction 3 less than or equal to 0.7 mumol/L (odds ratio, 4.9; CI, 2.9 to 8.3); and no previous outpatient diabetes education (odds ratio, 3.2; CI, 1.6 to 6.6). A logistic regression analysis done to control for the potentially confounding effects of age; race; socioeconomic status; diabetes duration, type, and severity confirmed these findings and added a statistically significant interaction between foot transcutaneous oxygen tension and peripheral vascular disease history. Clinical interventions to alter these risk factors were identified, including aggressive treatment of infection, diabetes education, protective footwear, and preventive footcare.
Multiple risk factors exist along the continuum of conditions and events leading to lower extremity amputation in diabetes. Modification of certain risk factors by patients and health professionals may reduce the risk for amputation and thus decrease the human and dollar costs that accompany limb loss in this prevalent chronic disease.
Thirty-eight amputations of the foot and ankle were performed in patients with peripheral vascular insufficiency over a 20-month period. Amputation level selection was based on clinical examination, a minimum ankle-brachial index of 0.5 as a measure of vascular supply, serum albumin of 3.0 gm/dl as a measure of tissue nutrition, and a total lymphocyte count of 1500 as a measure of immunocompetence. Transcutaneous oxygen tension was measured at the midfoot and ankle levels prior to surgery. Thirty-two of 38 patients (84.2%) healed their amputation wounds. When the transcutaneous oxygen tension was greater than 30 mm Hg, 24 of 26 patients (92.3%) healed. When the value was below 30 mm Hg, only eight of 12 patients healed.
When the propensity to support wound healing is factored out, with patients having the metabolic capacity to heal an amputation wound in the foot and ankle, it appears that transcutaneous oxygen tension is an accurate measure of vascular inflow to support amputation wound healing.
A prospective study with 4 years of follow-up involving 127 consecutive symptomatic patients (60.6% with claudication, 39.4% with critical ischemia) who underwent aortobifemoral bypass surgery is described. A new grading system for the classification of arterial outflow was applied to determine its usefulness in predicting the outcome of surgery. Preoperative angiograms were numerically scored according to the arterial outflow status at the level of main segmental involvement. Higher scores corresponded to worse outflows. Outflow scores ranged between 1 and 10 with a mean of 3.6 +/- 0.24. The main comparison was between patients with scores of less than 5 (group A, n = 80) and patients with scores of 5 or more (group B, n = 47). Better outflow was associated with higher postoperative mean increases in the ankle-brachial index (ABI) (group A, 0.35 +/- 0.03; group B, 0.17 +/- 0.04; P less than .001) and transcutaneous oximetry (PtcO2) (group A, 15.4 mm Hg +/- 1.8; group B, 8.4 mm Hg +/- 3.0; P = .01). At 4-year follow-up, group A had higher cumulative rates of patency (98.3% vs 78.0%, P less than .001), symptomatic relief (84.0% vs 23.3%, P less than .001), and palliation (67.0% vs 19.9%, P less than .001). In conclusion, angiographic outflow, as evaluated with the system described, successfully helped predict postoperative increases in ABI and PtcO2 and the cumulative rates of graft patency, symptomatic relief, and palliation.
Twenty elderly patients of both sexes complaining of exercise--induced or rest pain in limbs were studied in order to evaluate the presence of peripheral vascular occlusive disease (PAOD). The analysis of results was made on the basis of segmental pressure index (SPI) and transcutaneous oxygen pressure measurement (TcPO2). Seventeen limbs fell into the category of critical vascular insufficiency with TcPO2 below 30 mm Hg. In 10 limbs SPI volumes could not be obtained due to technical problem to take adequate Doppler signal equal to systolic pressure in a segment of the limb. We failed to find a good correlation between both techniques of measurements used.
The natural history of tissue repair and the critical determinants of faulty healing of diabetic ulcers remain obscure despite recent advances in our knowledge of the cellular physiology of normal cutaneous healing. To characterize the chronology and identify important factors affecting healing, we applied an objective method to quantify the rate of wound healing of full-thickness lower-extremity ulcers in 46 diabetic outpatients who received local wound care under a standardized clinical protocol. The initial ulcer healing rate, eventual status of tissue repair, and definitive clinical outcome were not significantly associated with age; diabetes type, duration, or treatment; level or change in glycosylated hemoglobin; current smoking; presence of sensory neuropathy; ulcer location or class; initial infection; or frequency of recurrent infections. However, direct measures of local cutaneous perfusion, estimated by periwound measurements of transcutaneous O2 tension (TcPo2) and transcutaneous CO2 tension (TcPco2), were significantly associated with the initial rate of tissue repair (P = 0.003 and 0.005, respectively). The strong prediction of early healing by these parameters of local skin perfusion was independent from the effects of segmental Doppler arterial blood pressure at the dorsalis pedis, although eventual ulcer reepithelialization was significantly related to foot blood pressure and periwound TcPo2 and TcPco2. We conclude that periwound cutaneous perfusion is the critical physiological determinant of diabetic ulcer healing, indicating a 39-fold increased risk of early healing failure when the average periwound TcPo2 is less than 20 mmHg.
The level of amputation continues to present a challenge for surgeons. In view of this, 24 patients who required an amputation of their ischaemic leg were studied prospectively using Laser Doppler flowmetry (LDF), TcpO2 measurements and Doppler ultrasound to assess the best level for amputation. In all patients gangrene of the leg and rest pain were the indication for an amputation. Skin oxygen tension (TcpO2) and skin blood flow (LDF) measurements were obtained the day before surgery on the proposed anterior and posterior skin flaps for below knee amputation and the maximum Doppler systolic pressure was measured. The level of amputation was chosen at surgery by clinical judgement without reference to the measurements mentioned above. A below knee amputation was performed in 17 patients and an above knee in seven. All amputations healed by primary intention. Doppler pressures showed poor discrimination with a median value of 10 mmHg (0-25) in AK patients and 35 mmHg (0-85) in the BK group (p greater than 0.05). In contrast TcpO2 showed a trend. In the BK group the median value was 20 mmHg (4-50) on the anterior and 22 mmHg (2-60) on the posterior flap compared to above knee amputees with median values of 6 mmHg (2-11) and 8 mmHg (3-38), respectively (p greater than 0.05). Laser Doppler seemed more useful. In BK patients the median LDF values were 36 mV (20-85) on the anterior and 34 mV (20-80) on the posterior flap with median LDF values of 10 mV (10-18) on the anterior and 11 mV (8-38) on the posterior flap in the above knee group (p less than 0.01). Laser Doppler flowmetry is a simple objective test, which is a better discriminator of skin flap perfusion than either TcpO2 or Doppler ankle pressures.
One hundred and forty patients with diabetic microangiopathy were studied by laser-Doppler flowmetry--measuring skin blood flow at rest (RF) and the venoarteriolar response (VAR)--by transcutaneous PO2 and PCO2 measurements and by evaluation of capillary permeability (rate of ankle swelling = RAS). Seventy were treated for 12 months with below-knee, elastic stockings. Seventy patients were left without compression acting as a control group. After 5 and 12 months there were no significant changes in the control group. However there was a significant improvement of microcirculatory parameters in patients treated with elastic compression. RF (increased at the beginning of the study) decreased. The VAR (impaired at the beginning of the study) improved significantly. PO2 (increased after treatment) and PCO2 (decreased) were also positively changed by elastic stockings. The abnormally increased capillary permeability was also improved. Elastic compression seems to be useful in diabetic microangiopathy improving microcirculatory parameters and decreasing capillary permeability and edema. However further studies, treating with elastic compression more patients for longer periods, are needed to confirm the positive effects of elastic stockings in improving diabetic microangiopathy and in slowing down its rate of progression.
This study was accomplished in an irradiated rabbit model to assess the angiogenic properties of normobaric oxygen and hyperbaric oxygen as compared with air-breathing controls. Results indicated that normobaric oxygen had no angiogenic properties above normal revascularization of irradiated tissue than did air-breathing controls (p = 0.89). Hyperbaric oxygen demonstrated an eight- to ninefold increased vascular density over both normobaric oxygen and air-breathing controls (p = 0.001). Irradiated tissue develops a hypovascular-hypocellular-hypoxic tissue that does not revascularize spontaneously. Results failed to demonstrate an angiogenic effect of normobaric oxygen. It is suggested that oxygen in this sense is a drug requiring hyperbaric pressures to generate therapeutic effects on chronically hypovascular irradiated tissue.
We report a prospective study with 2 years of follow-up including 105 consecutive symptomatic patients (58.1% claudication and 41.9% severe ischemia) undergoing aortobifemoral bypass surgery (ABF/BP). Proportional-hazards, stepwise regression, and life-table analyses were used to determine predictors of the following outcome criteria: graft patency, amputation, mortality, symptomatic recurrence, and palliation. The operative mortality was 5.7% and the 2-year cumulative mortality was 15.5%. Most deaths (61.5%) were cardiac-related. There were 3 predictors of mortality: the presence of more than 1 surgical risk factor (relative risk [RR] 6.2; p less than 0.001), advanced age (RR 2.9; p = 0.03) and the presence of ischemic heart disease (RR 1.5; p = 0.045). No patient required amputation. Early graft patency rate was 94.3% and the 2-year cumulative patency was 92.8%. The only predictor of graft failure was preoperative ankle/brachial index (ABI) of less than 0.4 (RR 6.1; p = 0.003). Early symptomatic relief was 98.1% and at 2 years it was 77.3%. There were 2 predictors of symptomatic recurrence: postoperative smoking (RR 2.4; p less than 0.001) and impaired runoff (RR 2.5; p = 0.017). Cumulative palliation was 87.6% at 1 month and 66.5% at 2 years postoperatively. There were 2 predictors of palliation: the presence of more than 1 surgical risk-factor (RR 1.8; p = 0.001) and postoperative transcutaneous oximetry (PtcO2) of less than 35 mmHg (RR 3.1; p = 0.04). We conclude that the best predictors of outcome in patients undergoing ABF/BP surgery were the number of preoperative risk factors, age, ischemic heart disease, ABI, PtcO2, postoperative smoking, and angiographic runoff.(ABSTRACT TRUNCATED AT 250 WORDS)
In a prospective study, transcutaneous oxygen tension and ankle-brachial pressure index (ABI) were measured pre- and postoperatively in 105 symptomatic patients who underwent aortobifemoral bypass to compare the ability of these two measurements to reflect the runoff status, determined by angiography, and to predict the outcome of surgery. Postoperatively, ABI better reflected the runoff status. The difference in mean ABI for good versus poor runoff was 0.17 (p less than 0.05). The difference in mean transcutaneous oxygen tension below the knee for the two runoff categories was relatively small (6.3 mm Hg, p less than 0.05). Post-minus preoperative increases in ABI reflected the runoff status better than increases in transcutaneous oxygen tension. For good runoff, the mean ABI increase was 0.25 and for poor runoff it was only 0.14 (p less than 0.05). Runoff and transcutaneous oxygen tension were found to be the best predictors of symptomatic recurrence. Poor runoff was associated with a relative risk of 2.5 (p = 0.017) and transcutaneous oxygen pressure of less than 40 mm Hg implied a relative risk of 2.3 (p = 0.029) for symptomatic recurrence. The most important predictor of graft failure was preoperative ABI. Transcutaneous oxygen tension and the ankle-brachial pressure index appear to be valuable noninvasive techniques for vascular assessment, offering different insights and different predictions for management and prognosis of peripheral vascular disease.
Various non-invasive vascular studies have been reported to provide valuable data for selection of the optimum level of amputation in limbs in patients who have vascular disease. We evaluated three such methods: (1) measurement of the change in the transcutaneous PO2 after inhalation of oxygen; (2) determination, by the Doppler method, of segmental blood pressure; and (3) measurement of the temperature of the skin. The records of eighty patients (ninety amputations) were retrospectively reviewed for correlations between the results of the vascular studies and the outcome of the amputation. Measurement of transcutaneous PO2 was found to be the most accurate predictor of successful healing of an amputation; the other two measurements were less reliable. The values for transcutaneous PO2 both at rest and after inhalation of oxygen were significantly different (p less than 0.001) for the patients who had a healed amputation compared with those who had a failed amputation. Regardless of the initial value, if, after inhalation of oxygen, the transcutaneous PO2 reached ten millimeters of mercury or more, it predicted healing of the amputation stump with a sensitivity of 98 per cent. When the level of amputation was selected on the basis of clinical judgment at the time of operation, the sensitivity was only 90 per cent.
Transcutaneous oxygen tension (TcPO2) and the effect of intermittent pneumatic compression on tissue oxygenation were studied in 10 patients with post-thrombotic leg ulcers. Oxygen tension was measured near the edge of the leg ulcer before and after 60 min of intermittent compression at 50 mmHg. The control group consisted of nine subjects with no evidence of peripheral vascular disease. The mean TcPO2 for the controls was 59.7 (SEM2.9) mmHg and for the study group 26.2 (SEM7.0) mmHg before treatment and 42.7 (SEM6.4) mmHg after treatment (p less than 0.005). Oxygen tension increased in nine patients in the study group. The change in TcPO2 correlated highly significantly (r = 0.912, p less than 0.002) with the reduction of oedema and the inverse change of skin temperature. The results suggest that intermittent pneumatic compression decreases interstitial fluid volume and venous stasis, both of which may lead to increased tissue oxygenation.
Fifty-seven patients with resting pain or tissue necrosis were found to have a forefoot transcutaneous tissue oxygen (tcPO2) level less than 30 mm Hg. The adjunctive measures of foot dependency (36 cm below heart level) and nasal oxygen of 3 L/min were evaluated in these patients. In general, the improvement in tcPO2 levels with these adjunctive measures was not related to basal levels of forefoot or arm tcPO2. One can expect an increase in tcPO2 level of approximately 22 mm Hg while employing the dependent position and an additional benefit of 12 mm Hg with the administration of nasal oxygen. Of the 35 patients with a basal forefoot tcPO2 level of less than 10 mm Hg, 11 did not respond to these adjunctive measures.
We measured local transcutaneous oxygen tension at the foot and proximal and distal to the knee in 162 patients who then had 206 amputations. When the values for oxygen tension at the foot and distal to the knee were compared with the success or failure of healing after an amputation of the foot or distal to the knee, respectively, a clearly increasing probability of failure was correlated with decreasing transcutaneous oxygen tension. However, even at a tension of zero the probability of failure was not 100 per cent. The results were similar for diabetic and non-diabetic patients. Preoperative values for transcutaneous oxygen tension were a much more consistent predictor of success or failure of healing after an amputation of the foot or distal to the knee than were measurements of systolic blood pressure at the ankle, but neither was predictive of the outcome after an above-the-knee amputation.
Transcutaneous oxygen and carbon dioxide pressure (PO2 and PCO2) foot monitoring was compared with ankle Doppler-derived systolic pressure regarding their respective abilities to discriminate the severity of limb ischemia before vascular reconstruction and to predict surgical outcome early in the postoperative period. Transcutaneous PO2 (tcPCO2), foot-chest tcPO2 index, transcutaneous PCO2 (tcPCO2), foot tcPO2/tcPCO2 index (tcPO2/tcPCO2), ankle Doppler systolic pressure (AP), and ankle-brachial pressure index (ABI) were determined in 89 revascularized limbs. The measurement of tcPO2 and foot-chest tcPO2 was found to be more sensitive to degrees of severity of limb ischemia and more closely associated with the outcome of revascularization than AP and ABI. TcPCO2 and tcPO2/tcPCO2 were not useful in assessment of the vascular patient undergoing reconstructive surgery. Before operation, tcPO2 less than or equal to 22 torr and foot-chest tcPO2 less than or equal to 0.46 indicate severe limb ischemia requiring urgent revascularization. After operation, tcPO2 less than or equal to 22 torr and foot-chest tcPO2 index less than or equal to 0.53 indicate that revascularization is likely to fail. We conclude that tcPO2 monitoring, as a metabolic test of actual tissue perfusion, is a more reliable indicator of preoperative limb ischemia and postoperative outcome of revascularization than hemodynamic, Doppler-derived pressure tests.
The present study examined prospectively the prognostic value of preoperative clinical findings, angiography, and conventional vascular hemodynamic and transcutaneous oximetry measurements in a consecutive series of patients undergoing lower extremity vascular reconstruction. A total of 25 variables were independently evaluated in each limb. Follow-up at least 6 months after operation was carried out in all patients. The postocclusive transcutaneous oxygen recovery time was found to be the most accurate predictor of short-term femoropopliteal bypass graft success. Preoperative foot transcutaneous oxygen recovery time values were significantly worse in patients whose femoropopliteal bypass grafts failed than in those in whom the outcome was successful (p less than 0.03). Transcutaneous oxygen recovery time values were also valuable in patients who underwent aortofemoral bypass; patients with isolated aortoiliac disease had significantly better foot transcutaneous oxygen recovery time values than those with combined aortoiliac and femoropopliteal disease (p less than 0.05). Foot transcutaneous oxygen recovery time values were also found to correlate well with the severity of symptoms (p less than 0.01), as did ankle-brachial Doppler pressure indices. Although the other variables analyzed provided useful diagnostic information, none were as accurate as the postocclusive transcutaneous oxygen recovery time in predicting the outcome of peripheral vascular reconstruction. As a means of more accurately classifying patients with peripheral vascular disease, we recommend the complimentary use of clinical findings, angiography, and hemodynamic and transcutaneous oximetry measurements. Because transcutaneous oxygen tension reflects the balance between local oxygen supply and demand, it may help to better define risk factors preoperatively in physiologic terms.
The predictive value of the pedal transcutaneous oxygen tension (tcPO2) and of the distal systolic blood pressure (SBP) in forecasting the necessity for later amputation has been studied in 26 patients suffering from severe chronic ischaemia of the lower limbs. In all these patients vascular surgery had failed or not been possible, and they were threatened by amputation; they suffered from trophic lesions, or pain at rest, or both. The great toe SBP averaged 10 mmHg (range 0 to 60 mmHg) and the pedal tcPO2 10 mmHg (range 2 to 45 mmHg). After six minutes of oxygen inhalation there was an increase in pedal tcPO2 of 9 mmHg (0 to 50 mmHg). After a follow-up period averaging 7 months (range 10 days to 13 months), 13 patients underwent an amputation and nine (five of whom had been amputated) died. The great toe SBP in the patients who required amputation was initially lower than in those who did not. The pedal tcPO2 also was lower in amputated than in non-amputated patients. There was no amputation in the group showing an increase of at least 10 mmHg after six minutes of oxygen inhalation; and conversely, all patients in whom the pedal tcPO2 increased less than 10 mmHg were amputated. Thus increase in the pedal tcPO2 after oxygen inhalation appears the best criterion for estimating the prognosis of severely ischaemic limbs.
Salvage of ischemic diabetic feet with advanced infrapopliteal and pedal arch atherosclerosis requires distal revascularization to heal skin envelope injuries. A series of 60 consecutive diabetic extremities with 41 nonhealing skin envelopes requiring distal tibial or pedal bypass in 83 percent has been reported. Four configurations of in situ bypass, including femoropopliteal, femorotibial, femoral sequential popliteal-tibial, and popliteal-tibial [3,9,11,17] were utilized with reversed and nonvein bypass to achieve a 93 percent hospital survival rate and 90 percent limb salvage with 80 percent graft patency at 36 months. Transcutaneous oxygen mapping was used to predict the healing of skin envelope injuries and late amputations after bypass. Postoperatively, limbs with transcutaneous oxygen values at the midfoot and surrounding skin injuries of more than 30 mm Hg rapidly healed, whereas those with midfoot values of more than 30 mm Hg but transcutaneous values surrounding skin injuries of less than 30 mm Hg had wound complications (p less than 0.001). Optimal limb salvage can be achieved with in situ bypass, sequential grafting, and high forefoot amputations if necessary. Transcutaneous mapping accurately predicts tissue healing and allows planning of the site and timing of late amputations.
A prospective randomized trial comparing hyperbaric oxygen and systemic antibiotics in the prevention of osteoradionecrosis was presented. The results indicated, in a high-risk population who required tooth removal in irradiated mandibles, that up-front hyperbaric oxygen produced an incidence of osteoradionecrosis of 5.4% as compared with the antibiotic group of 29.9% (P = .005). Hyperbaric oxygen should be considered a prophylactic measure when post-irradiation dental care involving trauma to tissue is necessary.
Noninvasive transcutaneous PO2 (TcpO2) determinations have been developed to study peripheral arterial occlusive disease. To evaluate this technique as a predictor of amputation outcome, a blind, prospective study of 101 patients undergoing 119 amputations (23 above-knee [AK], 57 below-knee [BK], and 39 forefoot) was performed. TcpO2 measurements were obtained from the dorsum of the foot and 10 cm distal to the patella, both prior to and 10 minutes after inhalation of 100% oxygen. On the basis of preliminary results, initial TcpO2 values greater than 10 mm Hg or an increase greater than 10 mm Hg after oxygen inhalation were considered to predict a successful outcome, whereas failure was predicted when the initial TcpO2 value was less than 10 mm Hg and the increase after oxygen inhalation did not exceed the 10 mm Hg level. In the BK amputation group the test was 95% sensitive, 100% specific, and 95% accurate. Retrospective utilization of the above criteria in patients who had undergone both oxygen inhalation testing and AK amputation suggested that 9 of 17 limbs (53%) might have undergone a more distal BK amputation successfully. These results document the effectiveness of an initial TcpO2 determination coupled with the response to 100% oxygen inhalation as an excellent predictor of the outcome of lower extremity amputations.
The method of preparation of a micro platinum-in-glass membrane-covered electrode is described. The electrode has a tip diameter of 2–5μ and can be used for measuring oxygen tension in soft tissues such as brain. Its resolution is high enough to allow measurement of intercapillary oxygen gradients. If the tip is covered by a sufficiently thin membrane the electrode can be used to record electrical activity of single cells concurrently with oxygen tesion. The diffusion zones of oxygen around capillaries in the cortex of rat brain appear to be in the form of truncated cones.
We measured transcutaneous oxygen tension (TcPo2) at a skin temperature of 44 degrees C on 319 limbs in an approximately equal number of nondiabetic and diabetic patients with peripheral vascular disease. Measurements were made above the knee, below the knee (BK), and on the dorsum of the foot. Nondiabetic limbs with leg/foot (the lesser of BK or foot) TcPo2 values below 20 mm Hg were significantly more likely to have ulcers, to have rest pain, or to require an amputation on the limb as compared with limbs with leg/foot TcPo2 values above 20 mm Hg. Patients with more severe symptoms had significantly reduced limb TcPo2 values, and these values were lower at more distal measurement sites. Generally, these results were similar in diabetic and nondiabetic patients without limb ulceration; however, the diabetic patients were more likely to have ulcers in the presence of high limb TcPo2. This observation suggests that ulceration in a substantial proportion of the diabetic patients may have resulted from factors other than insufficient cutaneous tissue oxygen delivery.
Regional transcutaneous oximetry is a new, noninvasive diagnostic technique for the investigation of peripheral vascular disease (PVD) that uses differences in limb and trunk transcutaneous PO2 to assess the adequacy of local perfusion. The application of such measurements would be of great importance in diabetes, in which limb ischemia is commonly difficult to assess. A group of diabetic subjects with symptomatic PVD was studied with regional oximetry, Doppler-assisted blood pressure measurements, and arteriography. Doppler studies correlated poorly to symptom grade and angiographie data, while oximetry clearly demonstrated limb hypoxia under the functional conditions appropriate to the patients’ clinical symptomatology. The superiority of oximetry to Doppler studies was highly significant (X2 = 12.64, P < 0.001). Regional transcutaneous oximetry should therefore be the non-invasive diagnostic test of choice in the initial evaluation of the diabetic limb for PVD.
Because of its dependence on the adequacy of local oxygenation, transcutaneous oximetry is a powerful tool for investigation of the pathophysiology of PVD and will, in the future, have wide-ranging applications to the diagnosis and therapy of PVD.
The clinical manifestations and prognosis of peripheral vascular disease (PVD) depend upon the severity of limb hypoxia. Transcutaneous oxygen tension (Ptco2) is related to tissue oxygenation, but limb Ptco2 varies with changes in systemic as well as peripheral oxygen delivery (Do2). Previously we have found that simultaneous assessment of limb and chest Ptco2 yields a ratio, or regional perfusion index (RPI), that is independent of systemic Do2 and accurately reflects the adequacy of limb perfusion. Analysis of segmental limb Ptco2, RPI, and position-induced RPI changes was performed in 24 control limbs and 14 limbs with intermittent claudication (IC), 8 limbs with rest pain (RP), and 7 limbs with gangrene (G). Control limbs had high RPI values that varied little with position. The IC group had modestly decreased RPIs in the supine position, but extremity RPIs decreased markedly during leg elevation. Patients with RP had ischemia while supine, but the RPI improved to nearly normal upon standing. Feet with G were hypoxic even in the standing position. Segmental RPI decreases correlated with the presence of significant arterial lesions. This correlation was unaffected by diabetes. Analysis of regional transcutaneous oximetry allows classification of PVD by quantitative criteria based upon the adequacy of limb perfusion under functional conditions. RPI is characteristically high in normal persons and low in persons with G. Limbs with marginally compensated perfusion may have nearly normal RPI values under some conditions, but typical ischemic changes are elicited by positional change and exercise. The ease of such provocation of RPI decreases constitutes an index of the severity of disease. Such quantitative assessments of limb hypoxia can form the basis for a physiologic approach to arterial reconstruction.
The transcutaneous oxygen pressure (tcPO2) was measured by a polarographic technique in the legs of 161 volunteers and compared with the levels found in 62 patients with ischaemic skin due to peripheral vascular disease. The results show that the tcPO2 was related to the degree of ischaemia and, in many cases, was a more accurate guide to the viability of the skin than clinical assessment. Measurement of the transcutaneous oxygen pressure in the leg at the site of amputation in 24 patients with peripheral vascular disease showed that a preoperative level greater than 40 millimetres of mercury at an electrode temperature of 44 degrees Celsius was necessary for the skin of the stump to heal. The technique is simple, non-invasive and reliable. The tcPO2 accurately reflects the physiological and pathological changes in the circulation of the skin. It has potential in many fields of surgery where careful assessment of the viability of the skin is necessary.
In order to develop transcutaneous oxygen tension (PtcO2) measurements into a practical method for assessing peripheral vascular disease, the relationships between extremity and chest wall PtcO2 were examined in subjects with and without systemic atherosclerotic disease. The ratio of extremity to chest PtcO2, or transcutaneous regional perfusion index (RPI) assessed limb oxygenation more reliably than did direct PtcO2 measurement by obviating the effects of changes in systemic oxygen delivery upon local PtcO2. The authors find that transcutaneous oximetry can be used during treadmill exercise testing and that the RPI is unchanged by exercise in all normal subjects. PtcO2 and RPI were then measured during rest, position change, and exercise testing in patients with intermittent claudication. Whereas normal subjects maintain a constant thigh and calf RPI during exercise, patients with intermittent claudication consistently manifested large decreases in RPI in these areas when they were exercised until symptomatic. The authors find no overlap between the responses of normal subjects and patients with claudication; positive findings are, therefore, highly specific for exercise-induced limb ischemia. Since transcutaneous RPI exercise testing is easily performed and highly reproducible, it is well suited to clinical use in the diagnosis and documentation of intermittent claudication. Furthermore, since limb ischemia can be quantified, this method lends itself both to grading the severity of disease and to evaluating clinical progression of disease. It is suggested that such a quantitative approach to evaluation of intermittent claudication may allow refinement and extension of the indications for operative intervention in patients with intermittent claudication.
The transcutaneous oxygen monitor, developed as a non-invasive method of measuring arterial oxygen tension in neonates, has recently been applied to measurement of skin ischaemia in peripheral vascular disease. Since peripheral vascular disease occurs in older age groups and more commonly in men than women, the effects of age and sex on the transcutaneous oxygen tension in the lower limb have been investigated. Two hundred and five normal volunteers of both sexes with a wide age range had measurements taken at a fixed point in the lower limb under similar conditions. The results showed no significant correlation between either the age or sex of the individual when compared to the transcutaneous oxygen tension.
An accurate method is needed to quantitate the healing potentials of the possible sites of amputation in dysvascular limbs. We evaluated the segmental transcutaneous measurements of PO2 in thirty-seven patients who required below-the-knee amputation because of peripheral vascular insufficiency. The fifteen patients with below-the-knee transcutaneous PO2 values of forty millimeters of mercury or more had no delay in healing of the below-the-knee amputation. Seventeen of nineteen patients with values of more than zero but less than forty millimeters of mercury had healing at the below-the-knee level, in two after local revision. The three patients who had below-the-knee values of zero required re-amputation above the knee.
The response of musculocutaneous and random-pattern flaps to bacterial inoculation was studied in dogs by intradermal injection of bacteria and deposition of bacteria into stable wound spaces created by wound cylinders. No difference could be demonstrated in the susceptibility to bacterial challenge in the different portions of the musculocutaneous flap and in normal skin. A larger area of necrosis was observed in the random-pattern flaps, and the distal part was significantly more susceptible to necrosis. While the musculocutaneous flaps recovered rapidly from the bacterial inoculation, necrosis was observed in the random-pattern flaps. The bacterial count increased in the wound spaces surrounded by the random-pattern flaps, leading to full-thickness flap necrosis. The bacterial count decreased in the wound spaces surrounded by musculocutaneous flaps; there was evidence of healing around the wound cylinders. The musculocutaneous flap demonstrates a greater resistance to bacterial inoculation than the random-pattern flap on both its cutaneous and muscular surfaces.
Transcutaneous oxygen tension (PtcO2) was used for noninvasive determination of blood supply in 25 patients evaluated for peripheral arterial disease. PtcO2 values were compared with segmental Doppler pressure, pulse volume recording, pulse reappearance time, and angiography in patients being evaluated for wound healing problems, amputations, and peripheral bypass procedures. PtcO2 was measured using a heated (45 degrees C) Clark polarographic electrode to quantitate the oxygen which diffuses from the dermal capillaries to the skin surface. Control PtcO2 values recorded over the chest or shoulder taken while patients were breathing room air were 78 +/- 8 mm Hg. PtcO2 values greater than 50 mm Hg predicted success for levels of amputation and for wound healing without reconstructive procedures; values of 40 mm Hg or less were associated with continued wound problems and complication after amputation. Increased PtcO2 values after vascular reconstruction of the legs predicted improved clinical status on follow-up examinations up to 6 months. PtcO2 predicted the extent of vascular disease as well as the other noninvasive tests and angiography. We conclude that (1) PtcO2 tension is a simple, accurate, noninvasive method to determine the appropriate level of amputation, wound healing potential, and effectiveness of bypass procedures, and (2) PtcO2 values correlate well with angiography and noninvasive evaluations.
To test the hypothesis that lower extremity transcutaneous oxygen (TcPO2) measurements can accurately predict severity of foot ischemia and can be used to select appropriate treatment (conservative versus operative) for patients with diabetes and tissue necrosis or ischemic rest pain.
Fifty-five patients with 66 limbs were prospectively treated from June 1993 to July 1994. Noninvasive hemodynamic arterial assessment and TcPO2 mapping of the involved limb were obtained before treatment was selected. If the transmetatarsal TcPO2 level was 30 mm Hg or greater, the patient's foot problem was managed conservatively with local wound care, debridement, or a minor foot amputation. If the transmetatarsal TcPO2 level was less than 30 mm Hg, arteriography was performed with the anticipated need for vascular reconstruction. The endpoints for determining treatment success or failure were complete wound healing or relief of ischemic rest pain.
Thirty-one of 36 (86%) limbs with an initial transmetatarsal TcPO2 level of 30 mm Hg or greater were treated successfully with conservative care, including 73% (11 of 15 feet) of limbs without a palpable pedal pulse. After either bypass or angioplasty, 20 of 24 (83%) limbs achieved a transmetatarsal TcPO2 level greater than 30 mm Hg and had complete resolution of their presenting foot problem. An initial or postintervention transmetatarsal TcPO2 level of 30 mm Hg or greater was more accurate (90%, p = 0.001) than a palpable pedal pulse (65%, p = 0.009), in predicting ultimate wound healing or resolution of rest pain.
TcPO2 mapping is a useful noninvasive modality that can prospectively determine severity of foot ischemia, aid in selecting appropriate treatment for patients with diabetes and foot salvage problems, and decrease the total cost of such care.
Postoperative assessment of amputation wound healing remains largely subjective in nature, being based on the physician's clinical judgement. These considerations significantly impact on the rehabilitation course, as premature prosthetic fitting may result in wound breakdown. Alternatively, delayed healing may result in prolonged hospital length of stay. Few attempts have been made to correlate objective parameters of limb perfusion with amputation wound healing or prosthetic fitting outcome during the rehabilitation phase of treatment. A pilot study was conducted, in which the transcutaneous oxygen monitor, a noninvasive device measuring transcutaneous partial pressure of oxygen (tcpO2), was applied to the stumps of 11 consecutive above-or below-knee amputees admitted for rehabilitation after amputation. All patients were tested within 1 wk of admission and 45 days of amputation. The treatment team was blinded as to the test results. A direct correlation was observed between wound healing outcome and tcpO2 results (Fisher's exact test [FET], P = 0.03), and no patient with a tcpO2 of < or 15 mm Hg healed during their rehabilitation stay (FET, P = 0.006). TcpO2 of < or = 15 mm Hg was significantly correlated with prolonged length of stay (Point Biserial Correlation Coefficient [rpbi], = -0.835; P = 0.01), delayed prosthetic fitting (rpbi = 0.742; p = 0.01), and poorer wound healing at admission (rpbi = 0.932; P = 0.001). Postoperative tcpO2 measurement may have use in objectively identifying patients at greater risk of delayed wound healing and prosthetic fitting, although further study is warranted.
Management of ischaemic ulcers in patients with compromised peripheral arterial circulations relies on the physical examination and the simple, non-invasive assessment of arterial supply. This study aims to determine if transcutaneous oxygen pressure (tcPO2) measurement can improve management decisions based on ankle or toe systolic blood pressure measurement. Twenty-two consecutive patients with ischaemic ulcers had tcPO2 measured and the ankle/brachial (ABI) and toe/brachial (TBI) indices calculated. Two months after surgery 12 of 22 (55%) ulcers were healing and 10 (45%) were indolent. Postoperative tcPO2 values were predictive of wound outcome (P < 0.001). A tcPO2 > 31 mmHg was invariably associated with healing whilst a tcPO2 < 28 mmHg was associated with indolence. Ankle/brachial indices and TBI were unable to be calculated in all patients due to falsely elevated pressures and hallux amputations, respectively, and neither was predictive of outcome (ABI P = 0.152, TBI P = 0.069). The response to revascularization was less in diabetic patients with a mean tcPO2 increase of 18 mmHg compared to non-diabetic patients with a mean tcPO2 increase of 37 mmHg. TcPO2 measurement appears to be a reliable technique that can influence ischaemic ulcer management.
TMo date, capillary microscopy, transcutaneous oximetry (tcpO2) and laser Doppler fluxmetry are frequently used in the investigation of skin microcirculation in patients with lower limb ischaemia. The concomitant microcirculatory disturbances may be useful in addition to macrocirculatory parameters to discriminate the different degrees of ischaemic severity. The best ways of application of these methods and the choice of the best parameters to assess ischaemia have been insufficiently investigated. Therefore, skin microcirculation was investigated with the use of these techniques in 130 patients with different stages of lower limb ischaemia, divided according to their ankle-to-brachial pressure index (ABI). Patients were investigated in the sitting and the supine position. Measurements were performed at rest and during reactive hyperaemia following arterial occlusion, and before and after local skin heating. The reactive hyperaemic response using laser Doppler fluxmetry differed in every patient group investigated. Capillary red blood cell velocity was markedly impaired in critically ischaemic patients (ABI < 25%). Transcutaneous oxygen pressure measurements at rest rendered the highest positive predictive value (PV; 87%) to classify patients as having clinically severe ischaemia (Fontaine 3 or 4). Ankle and toe pressure measurements provided a PV value of 78%. Microcirculatory parameters and techniques appear to be useful as an addition to standard macrocirculatory techniques to assess the severity of lower limb ischaemia. This is particularly of importance in patients in whom macrocirculatory parameters are unattainable.