Evaluation of a transcutaneous carbon dioxide monitor in severe obesity
ABSTRACT To determine the reliability of estimating arterial CO(2) pressure (PaCO(2)) using a recently introduced transcutaneous CO(2) pressure (PtcCO(2)) monitor in severe obese patients.
Observational and interventional study.
District hospital with respiratory ward and bariatric surgery unit.
PtcCO(2) was measured in 35 obese patients with varied pathology, including chronic obstructive pulmonary disease, obstructive sleep apnea syndrome and hypoventilation syndrome. Ten minutes after the probe had been attached to an earlobe, PtcCO(2) was recorded immediately before arterial blood sampling. The PtcCO(2) and PaCO(2) values obtained with two methods were compared by Bland-Altman analysis. In a subgroup of 18 obese patients with chronic obstructive pulmonary disease and/or obstructive sleep apnea syndrome with moderate to severe hypercapnia both PtcCO(2) and PaCO(2) were re-evaluated during continuous positive airways pressure (CPAP) or bi-level positive airway pressure (Bi-PAP) treatment.
The mean difference between PaCO(2) and PtcCO(2) was -1.4 mmHg, and the standard deviation of the difference was 1.3 mmHg. Bland-Altman analysis showed generally good agreement between the two methods with a 95% limit of agreement of -4 to 1.1. The agreement between methods did not significantly change before and during cPAP or Bi-PAP treatment in hypercapnic patients.
The accuracy of estimation of PaCO(2) by transcutaneous monitoring was generally good in comparison with standard arterial blood gases examination. The device appears to be promising for use in obese patients to evaluate abnormalities in their alveolar ventilation.
Article: Hypoventilation syndromes.[Show abstract] [Hide abstract]
ABSTRACT: In patients with impaired inspiratory muscle function or altered respiratory system mechanics, an imbalance between load and capacity can arise. The ventilatory control system normally compensates for this by increasing drive to maintain adequate alveolar ventilation levels, thereby keeping arterial CO2 within its normal range. To reduce work of breathing, a pattern of reduced tidal volume and increased respiratory rate occurs. This pattern itself may eventually reduce effective ventilation by increasing dead space ventilation. However, the impact of sleep on breathing and its role in the development of diurnal respiratory failure is often overlooked in this process. Sleep not only reduces respiratory drive, but also diminishes chemoresponsiveness to hypoxia and hypercapnia creating an environment where significant alterations in oxygenation and CO2 can occur. Acute increases in CO2 load especially during rapid eye movement sleep can initiate the process of bicarbonate retention which further depresses ventilatory responsiveness to CO2. Treatment of hypoventilation needs to be directed toward factors underlying its development. Nocturnal noninvasive positive pressure therapy is the most widely used and reliable strategy currently available to manage hypoventilation syndromes. Although this may not consistently alter respiratory muscle strength or the mechanical properties of the respiratory system, it does appear to reset chemosensitivity by reducing bicarbonate, resulting in a more appropriate ventilatory response to CO2 during wakefulness. Not only is diurnal hypoventilation reduced with noninvasive ventilation, but quality of life, functional capacity and survival are also improved. However, close attention to how therapy is set up and used are key factors in achieving clinical benefits. © 2014 American Physiological Society. Compr Physiol 4: 1639-1676, 2014.
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ABSTRACT: Analysis of mean transcutaneous capnography in consecutive patients undergoing polysomnography. Arq. Neuro-Psiquiatr. [online]. 2014, vol.72, n.11, pp. 841-844. ISSN 0004-282X. http://dx.doi.org/10.1590/0004-282X20140138. Transcutaneous capnography is a noninvasive method useful for analysis of the behavioral tendency of transcutaneous CO2 pressure (PtcCO2) in patients undergoing polysomnography, to evaluate respiratory sleep disorders. Objective Determine normative PtcCO2 values in normal patients undergoing polysomnography. Method One hundred seventy-nine patients who underwent polysomnography with simultaneous PtcCO2 measurement were assessed by means of a transcutaneous capnograph (TCM4 series from Radiomiter). Results The group classified as normal (N=53) presented a apnea/hypopnea index (AHI) <5 events/per hour of sleep and their age groups varied between 7 and 76 years of age. Conclusion Global mean values of PtcCO2 in the normal group had a Gaussian distribution that varied between 33.1 and 50.0 mmHg (SD 4,363). Such findings allowed the establishment of normative PtcCO2 values for normal individuals.Arquivos de Neuro-Psiquiatria 11/2014; 72(11). DOI:10.1590/0004-282X20140138 · 1.01 Impact Factor
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ABSTRACT: Transcutaneous capnography is a noninvasive method useful for analysis of the behavioral tendency of transcutaneous CO 2 pressure (PtcCO 2) in patients undergoing polysomnography, to evaluate respiratory sleep disorders. Objective: Determine normative PtcCO 2 values in normal patients undergoing polysomnography. Method: One hundred seventy-nine patients who underwent polysomnography with simultaneous PtcCO 2 measurement were assessed by means of a transcutaneous capnograph (TCM4 series from Radiomiter). Results: The group classified as normal (N=53) presented a apnea/hypopnea index (AHI) ,5 events/per hour of sleep and their age groups varied between 7 and 76 years of age. Conclusion: Global mean values of PtcCO 2 in the normal group had a Gaussian distribution that varied between 33.1 and 50.0 mmHg (SD 4,363). Such findings allowed the establishment of normative PtcCO 2 values for normal individuals. Keywords: polysomonography, transcutaneous capnography, CO 2 pressure. RESUMO A capnografia transcutânea é um método não invasivo útil para análise da tendência comportamental da pressão de CO 2 transcutânea (PtcCO 2) 1,2,3 em pacientes submetidos à polissonografia para análise de transtornos respiratórios do sono. Objetivo: Determinar valores normativos da PtcCO 2 em pacientes normais submetidos à polissonografia. Método: Foram analisados 179 pacientes submetidos à polissonografia com medida concomitante da PtcCO 2 através de um capnógrafo transcutâneo. Resultados: O grupo classificado como normal (N=53) apresentou índice de apnéia/hipopnéia (AIH) ,5 eventos/hora de sono e faixa etária variando de 7 a 76 anos. Conclusão: Os valores da média global da PtcCO 2 no grupo normal apresentaram distribuição gaussiana variando de 33,1 a 50,0 mmHg (DP 4.363). Tais achados permitiram a criação de valores normativos da PtcCO 2 para indivíduos normais. Palavras-chave: polissonografia, capnografia transcutânea, pressão de CO 2 .18th Annual Meeting of the APSS, Minneapolis; 05/2014