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The continued improvement of oxygenators is an important aspect of patient safety during cardiopulmonary bypass (CPB). The purpose of this study was to compare the Bard William Harvey HF-5700 oxygenator to the upgraded Bard Quantum HF-6700, which has recently been introduced into clinical practice. No clinical evaluation of this device has been published to date. The two oxygenators differ principally in that the Quantum has a smaller priming volume, achieved at the expense of a smaller membrane surface area which could result in sub-optimal gas exchange characteristics, increased haemolysis and increased platelet dysfunction during CPB. Twenty adult patients undergoing elective, first time coronary artery bypass grafting (CABG) were randomly assigned either to the HF-5700 (n=10) or to the HF-6700 (n=10) group. One patient underwent mitral valve repair in addition to CABG and was excluded from further study. There were no statistically significant differences in either preoperative or operative parameters between the two groups. Samples were obtained at the start of CPB, at 30 min, 60 min, at the end of CPB and at 1 h following termination of CPB. No significant differences between the two groups were found in oxygen transfer, haemolysis (plasma haptoglobin levels) or platelet function (a novel platelet activating factor (PAF)-induced platelet activation test) at any of the time points during CPB. It was concluded that the Quantum HF-6700 matches the HF-5700 for the parameters studied, whilst having the advantage of requiring a smaller priming volume.

The purpose of this study was to determine whether adhesion molecules and markers of cell activation were preferentially increased on blood neutrophils during cardiopulmonary bypass (CPB) and whether such effects were influenced by the use of a roller pump or a centrifugal pump. Forty-six patients undergoing open heart surgery were randomly allocated into either the roller or centrifugal groups. Blood (1 ml volumes) was removed from arterial and venous lines immediately before and 1 h after the start of bypass. Whole blood samples were immunolabelled and flow cytometry used to measure the distribution and expression of the adhesion molecules CD11b, CD18, CD62L on neutrophils, monocytes and lymphocytes, in addition to CD64 on neutrophils and monocytes, and CD14 on monocytes. The expression of CD11b was significantly enhanced on neutrophils in arterial and venous samples from both the roller pump (mean 84% and 100% increase, respectively; p < 0.001) and centrifugal pump (mean 74% and 73% increase, respectively; p < 0.001) groups. Neutrophil L-selectin expression increased to a small but significant extent in arterial and venous samples from the centrifugal pump group (mean 16% increase; p < 0.001) and in venous samples from the roller pump group (mean 10% increase; p < 0.01). Neither the percentage of neutrophils bearing CD11b/CD18, CD62L and CD64, nor the expression of adhesion molecules on lymphocytes and monocytes were modified by 1 h of bypass. These results suggest that patients subjected to CPB with roller or centrifugal pumps are equally at risk to neutrophil activation that could lead to increased interaction of these cells with blood vessel walls.

Background: Changes in cerebral blood flow (CBF) during cardiac operations have implications in terms of postoperative neurologic and neuropsychological dysfunction. Current techniques of CBF measurement are cumbersome and invasive. Transcranial Doppler sonography offers a noninvasive means of assessing changes in CBF. The aim of this study was validation of this technique with existing methods of CBF measurement during cardiac operations., Methods: We compared the changes in CBF using xenon-133 clearance with changes in middle cerebral artery velocity by transcranial Doppler sonography (VMCA) using pH-stat and alpha-stat acid-base management during cardiopulmonary bypass. Measurements were taken (1) before bypass, (2) at 28 degrees C on bypass, (3) at 37 degrees C on bypass, and (4) after bypass. Relative changes in CBF and VMCA, calculated as the percent change from the prebypass baseline value normalized to 100%, were used in this analysis., Results: During the hypothermic phase of cardiopulmonary bypass, CBF and VMCA increased by 45.9% and 51.8%, respectively (p < 0.001), during pH-stat acid-base management but decreased by only 26.4% and 22.4%, respectively (p < 0.0001), during alpha-stat acid-base management. Linear regression analysis of the absolute changes in CBF (mL . 100 g-1 . min-1) and VMCA (cm/s) showed a significant correlation (r = 0.60; r2 = 0.36; p < 0.0001), but a better correlation was obtained when relative changes in CBF and VMCA were compared (r = 0.89; r2 = 0.79; p < 0.0001)., Conclusions: Measurements of VMCA, expressed as relative changes of a pre-cardiopulmonary bypass level (using the noninvasive transcranial Doppler sonographic technique), can be used to examine CBF changes during cardiopulmonary bypass.

Background: Neutrophils are activated during cardiopulmonary bypass, and it is believed that they play an important role in the postoperative inflammatory response. The effects of neutrophils are mediated by the surface adhesion molecules L-selectin, beta 2-integrins, and platelet-endothelial cell adhesion molecule-1 (PECAM-1), and it has been reported that beta 2-integrins are upregulated and L-selectin downregulated by cardiopulmonary bypass. However, the time course of these changes and their relative importance are unclear., Methods and Results: To investigate the temporal changes in the expression of the neutrophil surface adhesion molecules L-selectin, beta 2-integrins, and PECAM-1 induced by cardiopulmonary bypass, we used immunofluorescent flow cytometry in blood samples obtained at various times (before anesthesia, before bypass, and 0.25, 0.5, 1, 2, 4, 24, and 48 hours after initiation of bypass) from patients undergoing routine coronary artery bypass graft surgery. Anesthesia had no effect on the expression of any of the study molecules. The expression of all beta 2-integrins was not significantly affected during the entire study period. The mean fluorescence (expressed as a percentage of control) of CD18 did not change significantly during the first 2 hours after the initiation of cardiopulmonary bypass, but then it declined by 4 hours (P = NS) and attained its lowest values after 24 and 48 hours. The mean fluorescence of CD11b and CD11c decreased by 2 and 4 hours and remained reduced after 24 hours and 48 hours. The expression of PECAM-I decreased rapidly after the initiation of cardiopulmonary bypass to achieve 60 +/- 8% of the preanesthesia control values (P < .05) after only 1 hour; it fell to its lowest after 4 hours (44 +/- 8%; P < .05); and then it recovered partially by 24 hours (60 +/- 11%; P < .05), with a further recovery toward control after 48 hours (77 +/- 8%; P = NS). The profile for the mean fluorescence of PECAM-I was identical to that observed with its expression. In contrast, the expression and mean fluorescence of L-selectin were not changed during the 48-hour period., Conclusions: This study has demonstrated that cardiopulmonary bypass in humans induces (1) a rapid reduction in the expression of PECAM-I of circulating neutrophils, (2) a later reduction of beta 2-intergrin activity without significant changes in their expression, and (3) no alterations in the expression and activity of L-selectin. Thus, although the mechanism for the absence of neutrophil upregulation of beta 2-integrins and downregulation of L-selectin (no activation) remains to be elucidated, the downregulation of PECAM-1 indicates an early neutrophil activation, and its inhibition may represent a target for reducing the inflammatory response usually associated with cardiopulmonary bypass.

Background: Various risk stratification systems have been developed in coronary artery bypass graft surgery (CABG), based mainly on patients undergoing procedures with cardiopulmonary bypass. Objective: To assess the validity and applicability of the Parsonnet score, the EuroSCORE, the American College of Cardiology/American Heart Association (ACC/AHA) system, and the UK CABG Bayes model in patients undergoing off-pump coronary artery bypass surgery (OPCAB) in the UK. Methods: Data on 2223 patients who underwent OPCAB in eight cardiac surgical centres were collected. Predicted mortality risk scores were calculated using the four systems and compared with observed mortality. Calibration was assessed by the Hosmer-Lemeshow (HL) test. Discrimination was assessed using the receiver operating characteristic (ROC) curve area. Results: 30 of 2223 patients (1.3%) died in hospital. For the Parsonnet score the HL test was significant (p < 0.001) and the receiver operating characteristic curve (ROC) area was 0.74. For the EuroSCORE the HL test was also significant (p = 0.008) and the ROC area was 0.75. For the ACC/AHA system the HL test was non-significant (p = 0.7) and the ROC area was 0.75. For the UK CABG Bayes model the HL test was also non-significant (p = 0.3) and the ROC area was 0.81. Conclusions: The UK CABG Bayes model is reasonably well calibrated and provides good discrimination when applied to OPCAB patients in the UK. Among the other three systems, the ACC/AHA system is well calibrated but its discrimination power was less than for the UK CABG Bayes model. These data suggest that the UK CABG Bayes model could be an appropriate risk stratification system to use for patients undergoing OPCAB in the UK. [ABSTRACT FROM AUTHOR]