Figure 1 - uploaded by Cathy Ross
Content may be subject to copyright.
Cardiopulmonary bypass circuit diagram. Diagram of cardiopulmonary bypass circuit showing locations of major components and the sensors for the EDAC Quantifier.
Source publication
Neurologic injury after cardiac surgery is principally associated with emboli. Although much work has focused on surgical sources of emboli, less attention has been focused on emboli associated with the heart-lung machine. We tested whether emboli are associated with discrete processes during cardiopulmonary bypass (CPB). One hundred patients under...
Citations
... Therefore, MBs during CPB remain a concern because of postoperative neurological deficits. Consequently, for several years, the generation mechanisms and defoaming techniques of MBs have attracted considerable attention [29,30], and monitoring the MB count rate during CPB has become critical [31][32][33][34]. The current CPB system is equipped with a noninvasive ultrasonic bubble sensor that can detect and warn about the presence of air bubbles with diameters > 300 μm. ...
... Embolism caused by MBs results in brain dysfunction and cognitive decline [41]. Although the size and number of MBs associated with cognitive decline are debated, emboli have been linked to such clinical outcomes [30,40]. Previous studies have suggested that MBs should be removed from venous reservoirs to reduce their number after arterial filtering [35]. ...
Microbubbles (MBs) are known to occur within the circuits of cardiopulmonary bypass (CPB) systems, and higher-order dysfunction after cardiac surgery may be caused by MBs as well as atheroma dispersal associated with cannula insertion. As complete MB elimination is not possible, monitoring MB count rates is critical. We propose an online detection system with a neural network-based model to estimate MB count rate using five parameters: suction flow rate, venous reservoir level, perfusion flow rate, hematocrit level, and blood temperature. Methods: Perfusion experiments were performed using an actual CPB circuit, and MB count rates were measured using the five varying parameters. Results: Bland?Altman analysis indicated a high estimation accuracy (R
<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>
>0.95, p<0.001) with no significant systematic error. In clinical practice, although the inclusion of clinical procedures slightly decreased the estimation accuracy, a high coefficient of determination for 30 clinical cases (R
<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>
=0.8576) was achieved between measured and estimated MB count rates. Conclusions: Our results highlight the potential of this system to improve patient outcomes and reduce MB-associated complication risk.
... 13 Nevertheless, a certain amount of emboli related to CPB can be prevented. 14,15 It has been observed that while larger bubbles usually embolize cerebral arterioles, causing focal ischemia and neuronal injury, small emboli navigate along the vessels, provoking an insult to the endothelium and triggering an inflammatory response, microvascular dysfunction, and cognitive decline. [16][17][18] Evidence suggests that priming with crystalloid solutions clears the air contained in the circuit only partially, leading to a variable bubble release during CPB. ...
... [16][17][18] Evidence suggests that priming with crystalloid solutions clears the air contained in the circuit only partially, leading to a variable bubble release during CPB. 15,19,20 Maneuvers altering the density and pressure in the circuit like CPB initiation, cardioplegia delivery, hemofiltration procedures, and line clamping may result in extrication of microbubbles contained in the oxygenator toward the aortic cannula. [21][22][23] Additionally, some authors have indicated that VAVD management and CPB initiation with an empty venous line may increase small-size GME release to the bloodstream. ...
... Previous literature pointed out that, after priming a circuit with crystalloid solutions, a certain amount of GME remains adhered to the oxygenation chamber, being released into the bloodstream during CPB initiation. 15,20,23 Arterial filters are specifically designed to eliminate GME from CPB circuits due to the pressure difference generated by the filter and the buoyancy of bubbles that divert them through the recirculation line. 35 During HAR maneuvers, the only output of the oxygenation chamber is the recirculation line conducting to a collector bag. ...
Particulate and gaseous microemboli (GME) are side effects of cardiac surgery that interfere with postoperative recovery by causing endothelial dysfunction and vascular blockages. GME sources during surgery are multiple, and cardiopulmonary bypass (CPB) is contributory to this embolic load. Hematic antegrade repriming (HAR) is a novel procedure that combines the benefits of repriming techniques with additional measures, by following a standardized procedure to provide a reproducible hemodilution of 300 ml. To clarify the safety of HAR in terms of embolic load delivery, a prospective and controlled study was conducted, by applying Doppler probes to the extracorporeal circuit, to determine the number and volume of GME released during CPB. A sample of 115 patients (n = 115) was considered for assessment. Both groups were managed under strict normothermia, and similar clinical conditions and protocols, receiving the same open and minimized circuit. Significant differences in GME volume delivery (control group [CG] = 0.28 ml vs. HAR = 0.08 ml; p = 0.004) and high embolic volume exposure (>1 ml) were found between the groups (CG = 30.36% vs. HAR = 4.26%; p = 0.001). The application of HAR did not represent an additional embolic risk and provided a four-fold reduction in the embolic volume delivered to the patient (coefficient, 0.24; 95% CI, 0.08-0.72; p = 0.01), which appears to enhance GME clearance of the oxygenator before CPB initiation.
... The complexity of the right atrial myxoma is the possibility of its destruction [9,10] during connection of a cardiopulmonary bypass machine [11][12][13][14][15]. Due to the high risk of embolic complications, we did beating-heart surgery with clamping of major vessels (aorta, pulmonary artery, and venae cavae). ...
... 39 Nevertheless, most clinicians agree that GME should be limited (and therefore VAVD levels) since the adult literature correlates outcomes negatively with increased GME numbers. 36,40,41 Ultrafiltration Ultrafiltration is another technique aimed at limiting hemodilution and transfusion requirements. Ultrafiltration is nearly universally utilized during pediatric CPB, and many centers use the technique after CPB as well. ...
Luiz Fernando Caneo,1 Gregory S Matte,2 Talya Frey31Pediatric Cardiac Surgeon - Heart Institute, University of Sao Paulo Medical School – Division of Pediatric Cardiac Surgery, Sao Paulo, Brazil; 2Department of Cardiac Surgery, Boston Children’s Hospital, Boston, MA, USA; 3Ward Family Heart Center, Children’s Mercy Hospital, Kansas City, MO, USAAbstract: Blood conservation has become an essential institutional initiative in cardiac surgery patients secondary to published reports associating transfusion with increased morbidity and mortality. Cardiopulmonary bypass (CPB) for children with congenital heart disease presents unique challenges in regard to transfusion practice. The circuit size relative to the pediatric patient’s circulating blood volume results in more hemodilution forcing clinicians to adopt several strategies to counteract this. It is generally agreed that the effects of hemodilution in this population are less well understood. That being said, there is evidence that neurologic outcomes are impacted by significant anemia in neonates and infants undergoing CPB. This adds to the level of concern clinicians should have when managing congenital heart surgery patients. Optimized surgical outcomes are dependent on neurologic outcomes. Specific transfusion guidelines for pediatric cardiac surgery still vary widely across institutions, and a safe minimum hematocrit on bypass has not been established. Evidence-based guidelines are more prevalent in adult cardiac surgery patients, but there are a growing number of reports for pediatrics. Clearly, well-defined operative strategies and a team approach will decrease blood product transfusions and minimize the associated risks in pediatric patients, especially in regard to neurologic outcomes. The ongoing development of evidence-based guidelines for pediatric perfusion will serve clinicians, and most importantly, their patients, well. The purpose of this review is to present current practice to limit blood transfusions in pediatric cardiac surgery exclusively inside the operating room and related to CPB as well as minimizing the side effects of the coagulation disturbances caused by the level of hemodilution these patients may encounter.Keywords: cardiopulmonary bypass, congenital heart disease, cardiac surgery, blood conservation strategies, blood transfusion
... To minimize the influence of brain embolic phenomena we excluded patients with heart valves repair or replacement surgeries. 8,14,15 . All patients received a standardized anaesthetic and CPB management. ...
Background:
Post-operative cognitive dysfunction (POCD) occurs in approximately 33-83% of patients after cardiac surgery with cardiopulmonary bypass (CPB). Recent clinical data suggest that real-time, intraoperative monitoring of patient- specific cerebrovascular autoregulation (CA) may help to prevent POCD by detecting individual critical limits for mean arterial pressure (MAP) outside which CA is impaired. Objectives of the study were to detect the episodes of impaired CA during cardiac surgery with CPB, and to investigate the association between CA impairment and POCD.
Methods:
The observational study of non-invasive ultrasonic volumetric CA monitoring included 59 patients undergoing elective coronary artery bypass graft surgery with CPB. All patients underwent series of neuropsychological tests the day before and ten days after the surgery in order to evaluate cognitive function.
Results:
22 patients (37%) experienced POCD, 37 patients (63%) showed no cognitive deterioration. The duration of the single longest CA impairment event was found reliably associated with occurrence of POCD (p < 0.05). The critical duration of the single longest CA impairment event was 5.03 minutes (odds ratio 14.5; CI 3.9- 51.8) for studied population.
Conclusions:
Prospective clinical study showed that single longest CA impairment may result in post-operative deterioration of mental abilities. The duration of the single longest CA impairment event is the risk factor that is associated with POCD.
... In fact, VAVD has been shown to increase the potential for gaseous microemboli (GME) [9,10] . While the effect of GME on overall pediatric patient outcomes is unclear [11] , most clinicians agree that, intuitively, we should minimize GME on bypass since the adult literature supports their negative impact on patient outcomes after cardiac surgery [12,13] . Therefore, while minimizing venous line tubing ID and maximizing the use of VAVD would decrease bypass circuit prime volume, other important considerations must be taken into account. ...
Objective:
Hemodilution is a concern in cardiopulmonary bypass (CPB). Using a smaller dual tubing rather than a single larger inner diameter (ID) tubing in the venous limb to decrease prime volume has been a standard practice. The purpose of this study is to evaluate these tubing options.
Methods:
Four different CPB circuits primed with blood (hematocrit 30%) were investigated. Two setups were used with two circuits for each one. In Setup I, a neonatal oxygenator was connected to dual 3/16" ID venous limbs (Circuit A) or to a single 1/4" ID venous limb (Circuit B); and in Setup II, a pediatric oxygenator was connected to dual 1/4" ID venous limbs (Circuit C) or a single 3/8" ID venous limb (Circuit D). Trials were conducted at arterial flow rates of 500 ml/min up to 1500 ml/min (Setup I) and up to 3000 ml/min (Setup II), at 36°C and 28°C.
Results:
Circuit B exhibited a higher venous flow rate than Circuit A, and Circuit D exhibited a higher venous flow rate than Circuit C, at both temperatures. Flow resistance was significantly higher in Circuits A and C than in Circuits B (P<0.001) and D (P<0.001), respectively.
Conclusion:
A single 1/4" venous limb is better than dual 3/16" venous limbs at all flow rates, up to 1500 ml/min. Moreover, a single 3/8" venous limb is better than dual 1/4" venous limbs, up to 3000 ml/min. Our findings strongly suggest a revision of perfusion practice to include single venous limb circuits for CPB.
... Because opening the heart is an important influence on the risk of stroke and RAO, [41][42][43] transcranial Doppler might be effective in characterizing emboli and providing guidance for intraoperative intervention. 44 However, its use has not altered the outcomes for cerebral complications, specifically, cognitive deficit. ...
Purpose:
To study the incidence and risk factors for retinal artery occlusion (RAO) in cardiac surgery.
Design:
Retrospective study using the National Inpatient Sample (NIS).
Methods:
The NIS was searched for cardiac surgery. Retinal artery occlusion was identified by International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. Postulated risk factors based on literature review were included in multivariate logistic models.
Main outcome measures:
Diagnosis of RAO.
Results:
A total of 5 872 833 cardiac operative procedures were estimated in the United States from 1998 to 2013, with 4564 RAO cases (95% confidence interval [95% CI], 4282-4869). Nationally estimated RAO incidence was 7.77/10 000 cardiac operative procedures from 1998 to 2013 (95% CI, 7.29-8.29). Associated with increased RAO were giant cell arteritis (odds ratio [OR], 7.73; CI, 2.78-21.52; P < 0.001), transient cerebral ischemia (OR, 7.67; CI, 5.31-11.07; P < 0.001), carotid artery stenosis (OR, 7.52; CI, 6.22-9.09; P < 0.001), embolic stroke (OR, 4.43; CI, 3.05-6.42; P < 0.001), hypercoagulability (OR, 2.90; CI, 1.56-5.39; P < 0.001), myxoma (OR, 2.43; CI, 1.39-4.26; P = 0.002), diabetes mellitus (DM) with ophthalmic complications (OR, 1.89; CI, 1.10-3.24; P = 0.02), and aortic insufficiency (OR, 1.85; CI, 1.26-2.71; P = 0.002). Perioperative bleeding, aortic and mitral valve surgery, and septal surgery increased the odds of RAO. Negatively associated with RAO were female gender (OR, 0.77; CI, 0.66-0.89; P < 0.001), thrombocytopenia (OR, 0.79; CI, 0.62-1.00; P = 0.049), acute coronary syndrome (OR, 0.72; CI, 0.58-0.89; P = 0.003), atrial fibrillation (OR, 0.82; CI, 0.70-0.95; P = 0.01), congestive heart failure (OR, 0.73; CI, 0.60-0.88; P < 0.001), DM 2 (OR, 0.74; CI, 0.61-0.89; P = 0.001), and smoking (OR, 0.82; CI, 0.70-0.97; P = 0.02).
Conclusions:
Risk factors for RAO in cardiac surgery include giant cell arteritis, carotid stenosis, stroke, hypercoagulable state, and DM with ophthalmic complications; associated with lower risk were female gender, thrombocytopenia, acute coronary syndrome, atrial fibrillation, congestive heart failure, DM 2, and smoking. Surgery in which the heart was opened (e.g., septal repair) versus surgery in which it was not (e.g., CABG) and perioperative bleeding increased the risk of RAO.
... J Extra Corpor Technol. 2016;48: [129][130][131][132][133][134][135][136] Elimination of gaseous microemboli (GME) has been the focus of numerous studies due to the effect GME may have on neurological outcomes, as well as morbidity and mortality for patients undergoing extracorporeal circulation (ECC) (1)(2)(3)(4)(5). These efforts have led to better understanding of GME generation, detection, and pathophysiology, as well as techniques and equipment designed for GME reduction (5)(6)(7)(8)(9)(10). ...
Gaseous microemboli (GME) are an abnormal physiological occurrence during cardiopulmonary bypass and extracorporeal membrane oxygenation (ECMO). Several studies have correlated negative sequelae with exposure to increased amounts of GME. Hypobaric oxygenation is effective at eliminating GME in hollow-fiber microporous membrane oxygenators. However, hollow-fiber diffusion membrane oxygenators, which are commonly used for ECMO, have yet to be validated. The purpose of this study was to determine if hypobaric oxygenation, compared against normobaric oxygenation, can reduce introduced GME when used on diffusion membrane oxygenators. Comparison of a sealed Quadrox-iD with hypobaric sweep gas (67 atm) vs. an unmodified Quadrox-iD with normal atmospheric sweep gas (1 atm) in terms of GME transmission during continuous air introduction (50 mL/min) in a recirculating in vitro circuit, over a range of flow rates (3.5, 5 L/min) and crystalloid prime temperatures (37°C, 28°C, and 18°C). GME were measured using three EDAC Doppler probes positioned pre-oxygenator, post-oxygenator, and at the arterial cannula. Hypobaric oxygenation vs. normobaric oxygenation significantly reduced hollow-fiber diffusion membrane oxygenator GME transmission at all combination of pump flows and temperatures. There was further significant reduction in GME count between the oxygenator outlet and at the arterial cannula. Hypobaric oxygenation used on hollow-fiber diffusion membrane oxygenators can further reduce GME compared to normobaric oxygenation. This technique may be a safe approach to eliminate GME during ECMO.
... The Luna Innovations hardware and software does not have the ability to distinguish gaseous emboli from particulate. We characterized our embolic data as GME given the greater likelihood that emboli detected after the ALF are gaseous as opposed to particulate (16). CPB equipment currently on the market either has integrated arterial line filtration in the 25-40 μ range or it includes external arterial line filtration in the 20-40 μ range (15). ...
Gaseous microemboli (GME) are known to be delivered to the arterial circulation of patients during cardiopulmo-nary bypass (CPB). An increased number of GME delivered during adult CPB has been associated with brain injury and postoper-ative cognitive dysfunction. The GME load in children exposed to CPB and its consequences are not well characterized. We sought to establish a baseline of arterial limb emboli counts during the conduct of CPB for our population of patients requiring surgery for congenital heart disease. We used the emboli detection and counting (EDAC) device to measure GME activity in 103 consecutive patients for which an EDAC machine was available. Emboli counts for GME <40 m and >40 m were quantified and indexed to CPB time (minutes) and body surface area (BSA) to account for the variation in patient size and CPB times. Patients of all sizes had a similar embolic burden when indexed to bypass time and BSA. Furthermore, patients of all sizes saw a threefold increase in the <40 m embolic burden and a five-fold increase in the >40 m embolic burden when regular air was noted in the venous line. The use of kinetic venous-assisted drainage did not significantly increase arterial limb GME. Efforts for early identification and mitiga-tion of venous line air are warranted to minimize GME transmission to congenital cardiac surgery patients during CPB.
... In the clinical setting, the size and number of emboli introduced to the CPB circuit are variably influenced by vent suction, haemofiltration, vacuum-assisted venous drainage, drug additions and air entrained to the venous line, which have all previously been well documented. 11,[14][15][16][17][18] Although the best performing system in terms of emboli handling was a non-integrated system, we did not demonstrate a systematic disadvantage for integrated systems per se and the potential for them to have other advantages must be acknowledged. For example, Gursu et al. 19 compared clinical variables, inflammatory responses and transfusion needs in thirty-six patients who underwent coronary artery surgery randomised to CPB using either a Sorin Synthesis integrated filtration system or the Sorin Dideco Compactflo oxygenator plus a separate ALF. ...
... Although the EDAC quantifier is considered to be technologically advanced in its ability to measure and count emboli, in general, it tends to underestimate the true diameter and undercount the emboli passing in the circuit. 15 Given the questions around the ability of the EDAC to accurately discriminate emboli less than 10 µm, we reported our results both including and omitting the 0-10 µm emboli counts. The inability of the EDAC to differentiate between solid and gaseous microemboli also leaves uncertainty as to the nature of the counted embolic load, though we suspect the vast majority are microbubbles. ...
... While there are numerous origins of emboli that may enter the patient's systemic circulation during cardiac surgery, transmission from the perfusion circuit continues to be reported. 14,15 It is, therefore, important that the reduction of emboli during CPB is not overlooked and remains the subject of continued investigation. This is especially true in the context of the re-design of CPB circuit components. ...
Objective:
To compare the emboli filtration efficiency of five integrated or non-integrated oxygenator-filter combinations in cardiopulmonary bypass circuits.
Methods:
Fifty-one adult patients underwent surgery using a circuit with an integrated filtration oxygenator or non-integrated oxygenator with a separate 20 µm arterial line filter (Sorin Dideco Avant D903 + Pall AL20 (n=12), Sorin Inspire 6 M + Pall AL20 (n=10), Sorin Inspire 6M F (n=9), Terumo FX25 (n=10), Medtronic Fusion (n=10)). The Emboli Detection and Classification quantifier was used to count emboli upstream and downstream of the primary filter throughout cardiopulmonary bypass. The primary outcome measure was to compare the devices in respect of the median proportion of emboli removed.
Results:
One device (Sorin Inspire 6 M + Pall AL20) exhibited a significantly greater median percentage reduction (96.77%, IQR=95.48 - 98.45) in total emboli counts compared to all other devices tested (p=0.0062 - 0.0002). In comparisons between the other units, they all removed a greater percentage of emboli than one device (Medtronic Fusion), but there were no other significant differences.
Conclusion:
The new generation Sorin Inspire 6 M, with a stand-alone 20 µm arterial filter, appeared most efficient at removing incoming emboli from the circuit. No firm conclusions can be drawn about the relative efficacy of emboli removal by units categorised by class (integrated vs non-integrated); however, the stand-alone 20 µm arterial filter presently sets a contemporary standard against which other configurations of equipment can be judged.
