Perfusion (United Kingdom)

Soluble endothelial adhesion molecule expression in clinical cardiopulmonary bypass (CPB) was investigated. Neutrophil-mediated endothelial injury plays an important role in CPB-induced organ dysfunction. The adhesion of neutrophil to the endothelium is central to this process. It has been well documented that CPB induces neutrophil activation and changes in neutrophil adhesion molecule expression, but the effect of CPB on endothelial cell activation is not known. This study was designed to measure soluble endothelial adhesion molecules during CPB.

We made serial measurements (by specific enzyme-linked immunoabsorbent assay) of plasma levels of the soluble endothelial adhesion molecules, ICAM-1 and E-selectin in patients undergoing routine CPB ( n =7) and in a control group (thoracotomy, n = 3).

The results show an initial significant decrease during CPB followed by an increase in plasma E-selectin from 29.3 ± 5.1 ng/ml (mean ± SEM) prebypass to 34.0 ± 5.4 ng/ml at 48 h postbypass. Likewise, plasma ICAM-1 significantly decreased during CPB and then increased from 246.3 ± 38.0 ng/ml before bypass to 324.8 ± 25.0 ng/ml and 355.0 ± 23.0 ng/ml at 24 and 48 h after bypass, respectively. The rise in levels is statistically significant ( p < 0.05).

This study shows a decrease in circulating ICAM-1 and soluble E-selectin during CPB and an increase in their levels at 48 h after CPB.

This study was undertaken to develop a recovery model of cardiopulmonary bypass (CPB) in rats. Twenty male Wistar rats (475-550 g) were anaesthetized, mechanically ventilated and the femoral vessels cannulated. The extracorporeal circulation circuit comprised a roller pump, a venous reservoir and a modified Capiox 308 paediatric membrane oxygenator. Priming consisted of 20 ml of fresh homologous blood and 15 ml of colloid. Anticoagulation was achieved with heparin (500 IU/kg). Blood gas analysis, blood pressure monitoring and survival studies were performed in CPB ( n=10) and Sham ( n=10) rats.

Partial CPB was always easily established and was conducted at a flow rate of 100 ml/kg/min for 90 min. Blood gas analysis and blood pressure data did not differ between the two groups. All CPB rats survived and the 3-week follow-up period remained uneventful.

The rat model of CPB was easy to perform and was associated with excellent survival. This recovery model should allow us to study the pathophysiological processes underlying post-CPB multiple organ dysfunction.

In infants, technologies for obtaining rapid, quantified measurements of cardiac output (CO) following weaning from cardiopulmonary bypass (CPB) or extracorporeal membrane oxygenation are not readily available. A new technique to measure CO based on ultrasound velocity dilution is described. It utilizes reusable probes placed on the extracorporeal circuit that permits convenient measurement of CO prior to decannulation. This report provides preliminary validation data in an animal model.

Three Yorkshire pigs (11-14 kg) were fully heparinized and cannulated via the right common carotid artery (cannula advanced to the aortic arch) and right atrium. Both the venous and arterial lines were instrumented with ultrasonic probes connected to a computer-monitoring system. A ‘stopcock bridge’ between the arterial and venous cannulas provided the access for saline injection and a controlled AV-shunt. For comparison, a vascular flow probe was fitted directly to the pulmonary artery (PA) in both animals and, for the larger animal, a PA catheter was inserted to obtain standard thermodilution measurements.

Linear regression analysis revealed a correlation between the CO by ultrasound dilution (CO UD) technique and the vascular probe and PA thermodilution techniques to be R²-0.94 and 0.81.

This pilot study demonstrated that the CO UD technique correlates to other benchmarks of CO measurements. This novel technology has specific application in the field of pediatric open heart surgery in that it would allow the surgeon to accurately and inexpensively measure the CO of neonatal and pediatric patients before and after surgical manipulation of the heart without the need for placement of additional catheters or probes.

One challenge in providing extracorporeal circulation is to supply optimal flow while minimising adverse effects, such as haemolysis. To determine if the recent generation constrained vortex pumps with their inherent design improvements would lead to reduced red cell trauma, we undertook a study comparing three devices. Utilizing a simulated short-term ventricular assist circuit primed with whole human blood, we examined changes in plasma free haemoglobin values over a six-day period. The three pumps investigated were the Maquet Rotaflow, the Levitronix PediVAS and the Medos Deltastream DP3.This study demonstrated that all three pumps produced low levels of haemolysis and are suitable for use in a clinical environment. The Levitronix PediVAS was significantly less haemolytic than either the Rotaflow (p<0.05) or the DP3 (p<0.05). There was no significant difference in plasma free haemoglobin between the Rotaflow and the DP3 (p=0.71).

We present the case of a newborn with complex congenital heart disease who was treated with a neonatal Norwood operation and total anomalous pulmonary venous return repair. During the Norwood reconstruction, a novel technique was utilized to perfuse the head, lower body, and heart continuously to minimize ischemic injury.

The aim of this study was to monitor and compare the changes in metabolism and blood flow in the skeletal muscles during cardiac operations performed with cardiopulmonary bypass (CPB) and operations without CPB (off-pump) by means of interstitial microdialysis (Figure 1). Surgical revascularization, coronary artery bypass grafting (CABG), was performed in 40 patients randomized to two groups. Twenty patients (On-Pump Group) were operated on using CPB, 20 patients (Off-Pump Group) were operated on without CPB. Interstitial microdialysis was performed by 2 probes of a CMA 60 (CMA Microdialysis AB, Solna, Sweden) inserted into the patient’s deltoid muscle. Microdialysis measurements were performed at 30-minute intervals. Glucose, lactate, pyruvate and glycerol as markers of basic metabolism and tissue perfusion were measured in samples from the first probe, using a CMA 600 Analyzer (CMA Microdialysis AB). Blood flow through the interstitium was monitored by means of dynamic microdialysis of ethanol as a flow-marker in the dialysates taken from the second probe (ethanol dilution technique). Results in both the groups were statistically processed and compared. Both the groups were similar in respect of preoperative characteristics. Dynamic changes of interstitial concentrations of the measured analytes were found in both the patient groups (on-pump vs. off-pump) during the operation. There was no significant difference in dialysate concentrations of glucose and lactate between the groups. Significant differences were detected in pyruvate and glycerol interstitial concentrations, lactate/pyruvate ratio and lactate/glucose ratio between the on-pump vs. off-pump patients. In the Off-Pump Group, pyruvate concentrations were higher and the values of concentrations of glycerol lower. The lactate/pyruvate ratio and the lactate/glucose ratio, indicating the aerobic and anaerobic tissue metabolism status, were lower in the Off-Pump Group. There was no significant difference in dialysate concentrations of ethanol as a flow-marker during the surgery in either of the groups. There was no statistically significant difference between the groups (On-Pump Group vs. Off-Pump Group) comparing the postoperative clinical outcome (ICU stay, ventilation duration, length of hospital stay). The dynamic changes in the interstitial concentrations of the glucose, glycerol, pyruvate and lactate were found in both the groups of patients (On-Pump Group and Off-Pump Group), but there was no difference in local blood flow when the ethanol dilution technique was used. These results showed significantly higher aerobic metabolic activity of the peripheral tissue of patients in the Off-Pump Group vs. the On-Pump Group during the course of cardiac revascularization surgery. Results suggest that extracorporeal circulation, cardiopulmonary bypass, compromises peripheral tissue (skeletal muscles) energy metabolism. These changes have no impact on the postoperative clinical outcome; no significant difference between the groups was found.

Objectives: Minimized cardiopulmonary bypass (MCPB) circuits have been shown to reduce cerebral and retinal microembolisation during coronary artery bypass graft (CABG) surgery compared to conventional CPB (CCPB) circuits. Our aim was to evaluate whether the reduction of microembolisation is sustained in aortic valve surgery, as well as to evaluate the effects of MCPB on inflammatory, endothelial, and platelet activation markers.

Material and methods: Patients were randomized to undergo aortic valve replacement (AVR), with or without CABG, with MPCB (n=20) or CCPB (n=20). After anaesthesia induction and termination of CPB, standardized digital retinal fluorescein angiography images were obtained on both eyes and analyzed in a blinded fashion. Blood samples were collected at eight time points until the third postoperative day.

Results: Fewer patients in the MCPB group showed evidence of microembolic perfusion defects on postperfusion retinal fluorescein angiographs compared to the CCPB group (37% vs. 63%, absolute difference 26%, 95% CI -5% -51%, P = 0.194). Polymorphonuclear leukocyte (PMN) elastase and von Willebrand factor release were statistically significantly reduced in the MCPB group, but there were no significant differences in other markers of inflammation, coagulation or endothelial activation. A significantly higher three-fold increase in the amount of shed blood was collected to the cell saver with a higher rate of intraoperative platelet transfusion in the MCPB group compared to CCPB.

Conclusions: The use of MCPB was associated statistically insignificantly with less retinal microemboli compared to CCPB. MCPB was complicated by excess bleeding and need for transfusion. The feasibility of MCPB techniques in valve surgery requires further studies.