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To evaluate the effects of pulsatile reperfusion on the post ischemic myocardium, two categories of sheep were put on cardiopulmonary bypass (CPB). In Category I, the hearts of 23 sheep were arrested by global ischemia for 30 min, reperfused with pulsatile flow in 10 animals (P group), and non pulsatile flow in 13 animals (NP group), and then defibrillated. The incidence of ventricular fibrillation was much higher in the NP group than the P group, 77% versus 40% (p < 0.05). The lipoperoxide products and creatinine kinase from coronary sinus blood were elevated, but there were no significant differences between the two groups during 2 hour reperfusion. In the P group, less ultrastructural damage was observed, and Na+ and H2O accumulations in the subendomyocardium were significantly less than in the NP group, at 7.11 +/- 0.60 versus 9.98 +/- 1.10 mg/g dry weight (p < 0.05) and 82.58 +/- 0.47% versus 84.3 +/- 0.38% (p < 0.05), respectively. In Category II, the ischemic time of 17 sheep (eight in the P group, nine in the NP group) was prolonged to 45 min, and animals were supported by CPB after defibrillation. Myocardial energy phosphates were measured with high-performance liquid chromatography, and triphenyltetrazolium chloride was used to delineate the infarct size. After 2 hour of reperfusion, there were no significant differences in myocardial AMP and ADP between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

The ionization degree and equation of state of dense xenon plasma were calculated by using self-consistent fluid variational theory for temperature of 4-30kK and density of 0.01-8.5gcm;{3} . The dense fluid xenon will be ionized at high pressures and temperatures. The ionization energy of xenon will be lowered due to the interactions among all particles of Xe, Xe+ , Xe2+ , and e . The ionization degree is obtained from nonideal ionization equilibrium, taking into account the correlative contributions to the chemical potential which is determined self-consistently by the free energy function. The composition of xenon has been calculated with given densities and temperatures in the region of partial ionization. The calculated results show a pressure softening regime at the onset of ionization. Comparison is performed with available shock-wave experiments and other theoretical calculations.

Erythrocyte aggregation is known to be affected by a number of factors including the concentration of various plasma proteins. This study was performed to examine the in vivo effect of hemodilution of plasma proteins on erythrocyte aggregation in patients undergoing cardiopulmonary bypass (CPB) surgery. Blood samples were taken before, during, and after operation from 40 coronary artery bypass grafting patients who were operated with CPB and concomitant hemodilution (CPB, n=20) and who without (nonCPB, n=20). Erythrocyte aggregation was determined with a LORCA aggregometer, during which all samples were standardized to a hematocrit level of 40%. Results showed that in the CPB patients the aggregation index (AI) dropped to 44% of its preoperative baseline level 5 minutes after the start of hemodilution (from 47.7 +/- 10.1 to 26.6 +/- 11.4, p

The membrane oxygenator is known to be superior to the bubble oxygenator, but little information is available about the difference between the hollow fiber and flat sheet membrane oxygenators with regard to pressure drop, shear stress, and leukocyte activation. In this study, we compared these 2 types of membrane oxygenators in patients undergoing cardiopulmonary bypass (CPB) surgery with special focus on leukocyte activation and pressure drop across the oxygenators. Plasma concentration of elastase, a marker indicating leukocyte activation, increased to 593 +/- 68% in the flat sheet oxygenator group versus 197 +/- 42% in the hollow fiber oxygenator group (p

Study objectives: Complement activation is a trigger in inducing inflammation in patients who undergo coronary artery bypass grafting (CABG) and is usually thought to be induced by the use of cardiopulmonary bypass (CPB), In this study, we examined whether tissue injury caused by chest surgical incision per se contributes to complement activation in CABG patients. Design: Prospective study. Setting: Thorax center in university hospital. Patients: Twenty-two patients undergoing CABG without CPB were prospectively divided into two groups: a small chest incision via an anterolateral thoracotomy representing a minimized tissue injury (lateral group, n = 8), and a conventional median sternotomy representing a large tissue injury (median group, n 14). Biochemical markers indicating complement activation as well as systemic inflammatory response were determined before, during, and after the operation. Measurements and results: Plasma concentrations of complement 3a increased in both the lateral and median groups right after chest incision (p

Background. Leukocyte filtration of systemic blood during cardiopulmonary bypass surgery to reduce post-operative morbidity has not yet been established because of the enormous leukocyte release from the third space. This study was designed to examine the efficiency and safety of leukocyte filtration by a new prototype large capacity leukocyte filter. Patients and methods. Patients undergoing cardiopulmonary bypass surgery were prospectively divided into two groups: a leukocyte removal group (n = 11) receiving leukocyte filtration during cardiopulmonary bypass and a control group (n = 20) with no filtration. The filtration efficiency was indicated by electronic leukocyte counts before and after filtration and the clinical efficiency to reduce post-operative morbidity was indicated by PaO2. Safety was indicated by monitoring the filtration pressure and leukocyte release products across the filter, as well as by examining the postfiltration filter by light and electron microscopy. Results. On an average, 75% of all entering leukocytes were removed by the filter. The post-operative PaO2, showed a tendency to improve after filtration. During filtration, the pressure across the filter material increased in five cases, accompanied by an increase in post-filter plasma hemoglobin and beta-glucuronidase. Within these filters accumulations of fibrin network with many trapped leukocytes were discovered microscopically. Conclusions. The filter was efficient in filtering leukocytes, but the filtration efficiency slowed at the end of filtration. Furthermore, the patients' post-operative parameters showed a tendency to improve after filtration. However, flow obstruction by means of clotting seems to be an important issue of safety involved in the filtration of large numbers of leukocytes for cardiopulmonary surgical patients. (C) 1999 Elsevier Science Ltd. All rights reserved.

Background. The cardiopulmonary bypass (CPB) circuit induces blood activation and a systemic inflammatory response in cardiac surgical patients. The CPB circuit treated with surface-modifying additive (SMA) has been found to reduce blood activation by in vitro and ex vivo experiments. This study evaluates the surface thrombogenicity and complement activation of SMA circuits during clinical CPB. Methods. Twenty patients undergoing corollary artery bypass grafting were randomly divided into two groups. In the SMA group (n = 10), all blood-contacting surfaces in the CPB circuit were treated or coated with SMA, whereas in the control group (n = 10) patients were perfused with an identical circuit without treatment. Results. During CPB, platelet count and beta-thromboglobulin were found similar in both the SMA and the control groups. Prothrombin activation indicated by fragment F1+2 was found less in the SMA group (p

Background. The aim of this prospective study was to determine whether the inflammation-associated clinical morbidity as well as the subclinical markers of the inflammatory response are reduced in patients who undergo minimally invasive coronary artery bypass grafting without cardiopulmonary bypass. Methods. From June 1995 to June 1996, 62 consecutive patients with isolated stenosis of the left anterior descending coronary artery were assigned randomly to two groups: 31 patients underwent minimally invasive coronary artery bypass grafting and 31 patients underwent conventional coronary artery bypass grafting with cardiopulmonary bypass. In a subgroup of 10 patients in each group, subclinical markers were measured to determine the level of the inflammatory response generated during the operation. Results. In the group that underwent minimally invasive coronary artery bypass grafting, leukocyte elastase, platelet beta-thromboglobulin, and complement C3a were unchanged at the end of the procedure compared with their baseline concentrations, whereas these inflammatory markers were increased significantly in the group that underwent conventional coronary artery bypass grafting with cardiopulmonary bypass. The patients who underwent minimally invasive coronary artery bypass grafting had a shorter duration of operation (104 +/- 28 versus 140 +/- 28 minutes; p

Patients undergoing lung transplantation are often confronted,vith a bleeding problem that may be due in part to the use of cardiopulmonary bypass and its activation of blood clotting and fibrinolysis. Objective: We performed a prospective study to determine whether and to what extent the clotting and fibrinolytic systems are being activated and whether low-dose aprotinin is effective in inhibiting blood activation during lung transplantation. Methods: Thirty lung transplantations performed on 29 patients were divided into a group with cardiopulmonary bypass alone (n = 12), a group with cardiopulmonary bypass and 2 x 10(6) KIL aprotinin administered at the beginning of bypass in the pump prime (n = 12), and a group without cardiopulmonary bypass (n = 6), Serial blood samples were taken from the recipient before anesthesia, seven times during the operation, and 4 and 24 hours thereafter, Results: Results show that in the group having cardiopulmonary bypass alone, the concentration of the clotting marker thrombin/antithrombin III complex increased significantly during the early phase of the operation (p

Leukocyte depletion during cardiopulmonary bypass has been demonstrated in animal experiments to improve pulmonary function, Conflicting results have been reported, however, with clinical depletion by arterial line filter of leukocytes at the beginning of cardiopulmonary bypass. In this study, we examined whether leukocyte depletion from the residual heart-lung machine blood at the end of cardiopulmonary bypass would improve lung function and reduce the postoperative inflammatory response. Thirty patients undergoing elective heart operations were randomly allocated to a leukocyte-depletion group or a control group. In the leukocyte-depletion group (n = 20), all residual blood (1.2 to 2.1 L) was filtered by leukocyte-removal filters and reinfused after cardiopulmonary bypass, whereas in the control group an identical amount of residual blood after cardiopulmonary bypass was reinfused without filtration (n = 10). Leukocyte depletion removed more than 97% of leukocytes from the retransfused blood (p

Background. Extreme dilution of clotting factors, as may occur during pediatric or neonatal cardiopulmonary bypass, often leads to inadequate monitoring of anticoagulation with activated dotting time (ACT). In this study we postulate that the high-dose thrombin time (HiTT) is less influenced by extreme dilution of clotting factors because it stimulates clotting through the common pathway. Methods. Heparinized prebypass blood was obtained from 30 adult cardiac surgical patients and was diluted in a laboratory setting with saline solution to mimic the clinical clear prime solution (group I; n = 10), with saline solution containing similar heparin as in the prebypass blood (group II; n = 10), and with fresh frozen plasma to substitute clotting factors in the diluted blood (group III; n = 10). Blood was diluted to four different degrees: a control without dilution, 25%, 50%, and 75% dilution. The ACT and HiTT were measured and compared. Results. Tn group I, significant prolongation of ACT was observed in blood diluted to 75% as compared with the nondiluted blood (p

Heparin coating of an extracorporeal circuit for cardiopulmonary bypass improves the hemocompatibility of the circuit and reduces the inflammatory response of the body. It has not been established, however, that heparin coating also improves postoperative hemostasis. We therefore performed a study in 30 patients who underwent a routine coronary artery bypass graft operation subjected to cardiopulmonary bypass with an uncoated (control) or a heparin-coated extracorporeal circuit (Duraflo II). We found significantly higher plasma levels of heparin in the Duraflo II group. However, we found no significant differences between the two groups with regard to other parameters of activation of the fibrinolytic and coagulation systems and to activation of platelets. Postoperative blood loss and donor blood transfusions were reduced in the Duraflo II group but not to a statistically significant extent. We conclude that heparin coating of an extracorporeal circuit improves anticoagulation but does not significantly reduce platelet activation, fibrinolysis, postoperative blood loss, and donor blood transfusions in routine coronary bypass operations.

Cardiopulmonary bypass generates a systemic inflammatory response including the activation of the complement cascade and leukocytes contributing to postoperative morbidity. To evaluate whether the use of heparin-coated extracorporeal circuits could reduce these activation processes, we performed a study on 30 patients undergoing coronary artery bypass grafting who were randomly perfused with a heparin-coated circuit (Duraflo II, n = 15) or with a similar noncoated circuit (control, n = 15). Standardized systemic heparinization was applied for every patient before cardiopulmonary bypass. The use of heparin-coated circuits resulted in a reduction of systemic leukocyte activation during cardiopulmonary bypass reflected by reduced elastase release (p

Endotoxin, when released into the systemic circulation during cardiopulmonary bypass (CPB), might induce activation of plasmatic systems and blood cells during CPB, in addition to a material-dependent blood activation during CPB. However, the role of endotoxin in the development of this so-called whole-body inflammatory reaction in CPB is still unclear. We investigated the release of endotoxin into the systemic circulation in relation with the activation of the complement system and in particular the formation of tumor necrosis factor in 10 patients undergoing CPB. Immediately after the start of CPB the endotoxin concentrations increased significantly (p

The effects of cardiopulmonary bypass (CPB) on the expression of leukocyte adhesive receptors, ie, complement receptor type 3 (CR3), were studied in 16 patients. The CR3 expression on leukocytes was determined by time-resolved fluoroimmunoassay on a standardized number of cells isolated from blood samples taken during various times during CPB. The results demonstrated that CR3 expression on leukocytes increased immediately after the start of CPB (p

The effect of blood activation on lung reperfusion injury during cardiopulmonary bypass was investigated in 20 dogs with the use of a bubble oxygenator (n = 10) or a membrane oxygenator (n = 10). In the bubble oxygenator group, significant leukocyte and platelet right to left atrium gradients were found 15 minutes after lung reperfusion (p