Abstract Recently, an oxygenator with an integrated centrifugal blood pump (IP) was designed to minimize priming volume and to reduce blood foreign surface contact even further. The use of this oxygenator with or without integrated arterial filter was compared with a conventional oxygenator and nonintegrated centrifugal pump. To compare the air removal characteristics 60 patients undergoing coronary artery bypass grafting were alternately assigned into one of three groups to be perfused with a minimized extracorporeal circuit either with the conventional oxygenator, the oxygenator with IP, or the oxygenator with IP plus integrated arterial filter (IAF). Air entering and leaving the three devices was measured accurately with a bubble counter during cardiopulmonary bypass. No significant differences between all groups were detected, considering air entering the devices. Our major finding was that in both integrated devices groups incidental spontaneous release of air into the arterial line in approximately 40% of the patients was observed. Here, detectable bolus air (>500 µm) was shown in the arterial line, whereas in the minimal extracorporeal circulation circuit (MECC) group this phenomenon was not present. We decided to conduct an amendment of the initial design with METC‐approval. Ten patients were assigned to be perfused with an oxygenator with IP and IAF. Importantly, the integrated perfusion systems used in these patients were flushed with carbon dioxide (CO 2 ) prior to priming of the systems. In the group with CO 2 flush no spontaneous air release was observed in all cases and this was significantly different from the initial study with the group with the integrated device and IAF. This suggests that air spilling may be caused by residual air in the integrated device. In conclusion, integration of a blood pump may cause spontaneous release of large air bubbles (>500 µm) into the arterial line, despite the presence of an integrated arterial filter. CO 2 flushing of an integrated cardiopulmonary bypass system prior to priming may prevent spontaneous air release and is strongly recommended to secure patient safety.
Various techniques for administration of blood cardioplegia are used worldwide. In this study, the effect of warm blood cardioplegia administration with or without the use of a roller pump on perioperative myocardial injury was studied in patients undergoing coronary artery bypass grafting using minimal extra-corporeal circuits (MECCs). Sixty-eight patients undergoing elective coronary bypass surgery with an MECC system were consecutively enrolled and randomized into a pumpless group (PL group: blood cardioplegia administration without roller pump) or roller pump group (RP group: blood cardioplegia administration with roller pump). No statistically significant differences were found between the PL group and RP group regarding release of cardiac biomarkers. Maximum postoperative biomarker values reached at T1 (after arrival intensive care unit) for heart-type fatty acid binding protein (2.7 [1.5; 6.0] ng/mL PL group vs. 3.2 [1.6; 6.3] ng/mL RP group, p = .63) and at T3 (first postoperative day) for troponin T high-sensitive (22.0 [14.5; 29.3] ng/L PL group vs. 21.1 [15.3; 31.6] ng/L RP group, p = .91), N-terminal pro-brain natriuretic peptide (2.1 [1.7; 2.9] ng/mL PL group vs. 2.6 [1.6; 3.6] ng/mL RP group, p = .48), and C-reactive protein (138 [106; 175] μg/mL PL group vs. 129 [105; 161] μg/mL RP group, p = .65). Besides this, blood cardioplegia flow, blood cardioplegia line pressure, and aortic root pressure during blood cardioplegia administration were similar between the two groups. Administration of warm blood cardioplegia with or without the use of a roller pump results in similar clinically acceptable myocardial protection.
The use of minimized extracorporeal circuits (MECC) in cardiac surgery is expanding. These circuits eliminate volume storage and bubble trap reservoirs to minimize the circuit. However, this may increase the risk of gaseous micro emboli (GME). To reduce this risk, a venous bubble trap was designed. This study was performed to evaluate if incorporation of a venous bubble trap in a MECC system as compared to our standard minimized extracorporeal circuit without venous bubble trap reduces gaseous micro emboli during cardiopulmonary bypass (CPB). Forty patients were randomly assigned to be perfused either with or without an integrated venous bubble trap. After preliminary evaluation of the data of 23 patients, the study was terminated prior to study completion. The quantity and volume of GME were significantly lower in patients perfused with a venous bubble trap compared to patients perfused without a venous bubble trap. The present study demonstrates that a MECC system with a venous bubble trap significantly reduces the volume of GME and strongly reduces the quantity of large GME (>500 µm). Therefore, the use of a venous bubble trap in a MECC system is warranted.
In Brief Reduction of the inflammatory reaction with the use of heparin coating has been found during and after cardiopulmonary bypass (CPB). The question remains whether this reduced reaction also decreases the magnitude of CPB-induced pulmonary dysfunction. We therefore evaluated the effects of a heparin-coated circuit versus a similar uncoated circuit on pulmonary indices as well as on inflammatory markers of complement activation (C3b/c), elastase-α1-antitrypsin complex, and secretory phospholipase A2 (sPLA2) during and after CPB. Fifty-one patients were randomly assigned into two groups undergoing coronary artery bypass grafting with either a heparin-coated (Group 1) or an uncoated (Group 2) circuit. During CPB, a continuous positive airway pressure of 5 cm H2O and a fraction of inspired oxygen (FIO2) of 0.21 were maintained. Differences in favor of the coated circuit were found in pulmonary shunt fraction (P < 0.05), pulmonary vascular resistance index (P < 0.05), and PaO2/FIO2 ratio (P < 0.05) after CPB and in the intensive care unit. During and after CPB, the coated group demonstrated lower levels of sPLA2. After CPB, C3b/c and the elastase-α1-antitrypsin complex were significantly less in the coated group (P < 0.001). The coated circuit was associated with a reduced inflammatory response, decreased pulmonary vascular resistance index and pulmonary shunt fraction, and increased PaO2/FIO2 ratio, suggesting that the coated circuit may have beneficial effects on pulmonary function. The correlation with sPLA2, leukocyte activation, and postoperative leukocyte count suggests reduced activation of pulmonary capillary endothelial cells. IMPLICATIONS: Heparin coating of the extracorporeal circuit reduces the inflammatory response during cardiopulmonary bypass. Analysis of indices of pulmonary function indicates that use of heparin coating may result in less impaired gas exchange.
Minimally invasive extracorporeal circulation systems are developed to decrease the deleterious effects of cardiopulmonary bypass. For instance, prime volume and foreign surface area are decreased in these systems. However, because of the lack of a venous reservoir in minimized systems, air handling properties of these minimally invasive extracorporeal circulation systems may be decreased as compared to conventional cardiopulmonary bypass systems. The aim of this in vitro study is to compare the air handling properties of two complete minimized cardiopulmonary bypass systems of two manufacturers, of which one system is provided with the air purge control. In an in vitro study, two minimally invasive extracorporeal circulation systems, Inspire Min.I manufactured by Sorin Group Italia, Mirandola, Italy (LivaNova, London, United Kingdom) and minimized extracorporeal circulation manufactured by Maquet, Rastatt, Germany (Getinge, Germany), were challenged with two types of air challenges; a bolus air challenge and a gaseous microemboli challenge. The air removal characteristics of the venous bubble traps and of the complete minimally invasive extracorporeal circulation systems were assessed by measuring the gaseous microemboli volume and number downstream of the venous bubble traps in the arterial line with a bubble counter. No significant differences were observed in air reduction between the venous bubble traps of Getinge (venous bubble traps) and LivaNova (Inspire venous bubble traps 8 in conjunction with the air purge control). Similarly, no significant differences were observed in volume and number of gaseous microemboli in the arterial line of both complete minimally invasive extracorporeal circulation systems. However, the gaseous microemboli load of the Inspire Min.I system was marginally lower after both the bolus air and the gaseous microemboli challenges. Both minimally invasive extracorporeal circulation systems assessed in this study, the LivaNova Inspire Min.I and the Getinge minimized extracorporeal circulation, showed comparable air removal properties, after both bolus and gaseous microemboli air challenges. Besides, air purge control automatic air removal system provided with the LivaNova Inspire Min.I. system may enhance patient’s safety with the use of a minimally invasive extracorporeal circulation system. We consider both systems equally safe for clinical use.
Background: Cerebral oximetry is a non-invasive tool for identifying silent desaturation during cardiac surgery. Peri-operative desaturation may require rapid interventions to avoid adverse events, including delirium. Most desaturations during cardiac surgery occur in both hemispheres. Our objective was to evaluate the difference in applying a single cerebral oximetry sensor versus a dual sensor for preventing delirium in coronary artery bypass grafting and valve surgery. Methods: We conducted a single-center, retrospective study of all patients undergoing coronary artery bypass grafting and valve surgery between January 2016 and December 2017. Before surgery, we identified any cerebral low flow state by transcranial Doppler ultrasound and either restored cerebral flow prior to surgery or, if that was not possible, waived surgery and offered the patient alternative non-surgical therapies, such as coronary angioplasty. In 2016, patients undergoing cardiac surgery were monitored with bilateral oximetry sensors (control group), whereas a single sensor was used in 2017 (study group). Results: Bilateral sensors were used in 508 patients and a single oximetry sensor in 498 patients. The use of a unilateral sensor did not influence the delirium rate. Regression analysis confirmed our null hypothesis. The primary outcome delirium rate was not significantly different between the control (bilateral sensors) group (6.4%) and the study (unilateral sensor) group (5.4%) (p = 0.472, OR 1.21 [95%CI 0.72 – 2.05]). Conclusions: Using a single cerebral oximetry sensor instead of bilateral sensors may reduce both the cost of monitoring and the threshold for applying cerebral oximetry during cardiac surgery without influencing the delirium rate.
Hemodilution is the main cause of a low hematocrit concentration during cardiopulmonary bypass. This low hematocrit may be insufficient for optimal tissue oxygen delivery and often results in packed cell transfusion. Our objective in this study was to find a relationship between intraoperative hematocrit and allogeneic blood transfusion on release of postoperative injury markers from the kidneys and the splanchnic area.Fifty consecutive patients undergoing coronary artery bypass grafting with cardiopulmonary bypass were included. Systemic tissue hypoxia was assessed by lactate concentrations. Kidney and splanchnic ischemia were assessed by the measurement of N-acetyl-beta-D-glucosaminidase (NAG) and intestinal fatty acid binding protein (IFABP) in urine. Patients were retrospectively placed into groups according to their lowest hematocrit concentration on bypass (<24% or >or=24%).The intraoperative lactate and the postoperative NAG and IFABP concentrations were higher in the low hematocrit group (<24%) than in the high hematocrit group (>or=24%; P < 0.05). Low hematocrit correlated with higher lactate concentrations (R(2) = 0.150, P < 0.01) and with higher NAG concentrations (R(2) = 0.138, P < 0.01) and IFABP concentrations (R(2) = 0.107, P < 0.01) postoperatively. Transfusion of packed cells during cardiopulmonary bypass correlated with higher lactate (R(2) = 0.089, P < 0.05), NAG (R(2) = 0.431, P < 0.01), and IFABP concentrations (R(2) = 0.189, P < 0.01).The results support the concept that hemodilution below an intraoperative hematocrit of 24% and consequently transfusion of red blood cells is related to release of injury markers of the kidneys and splanchnic area.
The use of mini cardiopulmonary bypass circuits is an emerging technology. The venous and cardiotomy reservoir have been excluded from the circuit. This results in a reduction of the blood contact surface area and of the priming volume. Entrainment of venous air, however, remains a drawback in the widespread acceptance of using these mini circuits. The technique described resolves this problem by automatic removal of venous air, and explains how this mini cardiopulmonary bypass circuit was utilized on a 64-year-old female presented for a mitral valve repair. In the absence of a cardiotomy reservoir, an autotrans-fusion cell separator was used to process shed blood and, after CPB, the residual pump blood. This mini bypass circuit, with the safety feature to remove automatically venous air, provided an additional degree of protection. In our experience, mini bypass circuits allow us safely to perform cardiopulmonary bypass during valve procedures.
The inflammatory reaction of extracorporeal circuits can be assessed by measuring complement activation and the release of activation markers of leucocytes. The purpose of this study was to compare three commercially available membrane oxygenators with respect to complement (C3a), granulocyte (lactoferrin) and monocyte (interleukin-6, IL-6) activation. Thirty patients undergoing cardiac surgery were randomly assigned to undergo cardiopulmonary bypass (CPB) with one of the following oxygenators: a polypropylene hollow-fibre membrane (group 1; 2.2 m2), a polypropylene flat-sheet membrane (group 2; 3.1 m2) or a silicone envelope membrane (group 3, 3.5 m2). In all patients, a significant increase in C3a in plasma occurred during CPB with peak levels after the administration of protamine sulphate. In blood samples taken before aortic crossclamp release, at the end of CPB, and 20 min after protamine administration C3a was significantly lower in group 1 than in the other two groups. Lactoferrin increased significantly during CPB in all patients without a significant difference between the groups. IL-6 did not increase during CPB, but raised significantly after 4 h in the intensive care unit in all groups. Moreover, IL-6 was significant lower in group 1 than group 3. The data suggest that the polypropylene hollow-fibre membrane oxygenator, i.e. the oxygenator with the smallest surface area, is more biocompatible than the other types, probably because of a smaller contact surface area.
The study compared the effects of three blood concentration techniques after cardiopulmonary bypass on clinical hemostatic and ex-vivo rheological parameters. Residual blood of patients undergoing elective cardiac surgery was processed by centrifugation, cell salvage or ultrafiltration, and retransfused (n = 17 per group). Study parameters included blood loss, (free) hemoglobin, hematocrit, fibrinogen and erythrocyte aggregation, deformability and 2,3-diphosphoglycerate content. Patient characteristics were similar between groups. Ultrafiltration was associated with the highest weight of the transfusion bag [649 ± 261 vs. 320 ± 134 g (centrifugation) and 391 ± 158 g (cell salvage); P < 0.01]. Cell salvage resulted in the lowest hemolysis levels in the transfusion bag. Retransfusion of cell saver blood induced the largest gain in postoperative patient hemoglobin levels when compared to centrifugation and ultrafiltration, and was associated with the largest increase in 2,3-diphosphoglycerate when compared to ultrafiltration (Δ2,3-diphosphoglycerate 1.34 ± 1.92 vs. −0.77 ± 1.56 mmol/l; P = 0.03). Cell salvage is superior with respect to postoperative hemoglobin gain and washout of free hemoglobin when compared to centrifugation or ultrafiltration.
