Aspects of retransfusion of shed blood in cardiac surgery

The use of cardiotomy suction during open heart surgery with cardiopulmonary bypass (CPB) has a long tradition and often regarded as mandatory. Recently, studies have described potentially negative effects of cardiotomy suction with activation of the complement system, enhanced inflammatory response, hemolysis and coagulopathy. Emboli of various matters has also been studied. Whether they affect the function of various organs is an ongoing debate. Renal dysfunction after cardiac surgery is a well known complication. Monitoring of renal function is important, both for the guidance of renal intervention and for the prediction of outcome. Cystatin C has been suggested as a more sensitive marker of glomerular filtration rate (GFR) than creatinine, which today is the most commonly used marker of GFR. In study I and II, we studied the distribution and the kinetics of lipid microemboli during cardiac surgery in a porcine model. The organ that received most emboli was the kidney. Within the brain, the grey matter received most emboli. A high degree of first-pass trapping in the capillaries was found. No immediate renal excretion of lipid material was seen. In study III, we evaluated cystatin C with iohexol clearance in a clinical study on patients scheduled for coronary artery bypass grafting (CABG). We found that cystatin C is suitable for monitoring renal function in cardiac surgery. In study IV, the final part of this thesis, we launched a clinical trial including 150 patients, where we compared outcome between CABG with and without cardiotomy suction. There were a few differences, all favoring surgery without the use of cardiotomy suction. No difference was found regarding renal function. We could conclude that CABG with CPB can be conducted safely without using cardiotomy suction and retransfusion of shed blood, as long as the surgeon is vigilant on the blood loss and prepared to use cardiotomy suction when needed

Incidence, dynamics, and prognostic value of acute kidney injury for death after cardiac surgery.

This study relates long-term mortality after cardiac surgery to different methods of measuring postoperative renal function, classified according to the Risk, Injury, Failure, Loss, and End-stage (RIFLE) criteria. The dynamics of acute kidney injury during hospital stay were studied by comparing renal function preoperatively, at its poorest measurement, and at discharge

Cardiorespiratory effects of venous lipid micro embolization in an experimental model of mediastinal shed blood reinfusion

<p>Abstract</p> <p>Background</p> <p>Retransfusion of the patient's own blood during surgery is used to reduce the need for allogenic blood transfusion. It has however been found that this blood contains lipid particles, which form emboli in different organs if the blood is retransfused on the arterial side. In this study, we tested whether retransfusion of blood containing lipid micro-particles on the venous side in a porcine model will give hemodynamic effects.</p> <p>Methods</p> <p>Seven adult pigs were used. A shed blood surrogate containing 400 ml diluted blood and 5 ml radioactive triolein was produced to generate a lipid embolic load. The shed blood surrogate was rapidly (<2 minutes) retransfused from a transfusion bag to the right atrium under general anesthesia. The animals' arterial, pulmonary, right and left atrial pressure were monitored, together with cardiac output and deadspace. At the end of the experiment, an increase in cardiac output and pulmonary pressure was pharmacologically induced to try to flush out lipid particles from the lungs.</p> <p>Results</p> <p>A more than 30-fold increase in pulmonary vascular resistance was observed, with subsequent increase in pulmonary artery pressure, and decrease in cardiac output and arterial pressure. This response was transient, but was followed by a smaller, persistent increase in pulmonary vascular resistance. Only a small portion of the infused triolein passed the lungs, and only a small fraction could be recirculated by increasing cardiac output and pulmonary pressure.</p> <p>Conclusion</p> <p>Infusion of blood containing lipid micro-emboli on the venous side leads to acute, severe hemodynamic responses that can be life threatening. Lipid particles will be trapped in the lungs, leading to persistent effects on the pulmonary vascular resistance.</p

Increased long-term mortality with plasma transfusion after coronary artery bypass surgery.

PURPOSE: Patients undergoing cardiac surgery often require transfusions of red blood cells, plasma and platelets. These components differ widely in both indications for use and composition. However, from a statistical point of view there is a significant colinearity between the components. This study explores the relation between the transfusion of different blood components and long-term mortality. METHODS: A retrospective single-centre study was performed including 5,261 coronary artery bypass grafting patients, excluding patients receiving more than eight units of red blood cells, those suffering early death (7 days) and emergency cases. Patients were followed up for a period of up to 7.5 years. A broad spectrum of potential risk factors was analysed using Cox proportional hazards survival regression. Non-significant risk factors were removed by step-wise elimination, and transfusion of red blood cells, plasma and platelets was forced to remain in the model. RESULTS: The transfusion of red blood cells was not associated with decreased long-term mortality (HR = 1.007, p = 0.775), whereas the transfusion of plasma was associated with decreased long-term survival (HR = 1.060, p < 0.001), and the transfusion of platelets was associated with increased long-term survival (HR = 0.817, p = 0.011). The risk associated with transfusion of plasma was mainly attributed to patients receiving large amounts of plasma. All hazard ratios are per unit of blood product transfused. CONCLUSIONS: No association was found between the transfusion of red blood cells and mortality during the study period. However, transfusion of plasma was associated with increased mortality while transfusion of platelets was associated with decreased mortality during the study period

Evaluation of cystatin C with iohexol clearance in cardiac surgery.

Post-operative renal dysfunction after cardiac surgery is not uncommon and can lead to adverse outcome. The ability to accurately monitor renal function is therefore important. Cystatin C is known to be a sensitive marker of the glomerular filtration rate (GFR), but it has not been fully evaluated in cardiac surgery. Iohexol clearance is considered a reliable reference method for the determination of GFR. The aim of this study is to, for the first time, evaluate the diagnostic accuracy of plasma cystatin C compared with iohexol clearance in cardiac surgery

Lipid emboli distribution in cardiac surgery is dependent on the state of emulsification

Objective. Lipid embolizations from retransfused shed blood during cardiac surgery have been shown to enter the circulation and end up in different organs. The purpose of this investigation was to evaluate differences in the kinetics and deposition between emulsified and non-emulsified lipid emboli in a porcine model. Design. Twelve animals were anesthetized and put on cardiopulmonary bypass. A shed-blood phantom (6 animals given emulsified and 6 given non-emulsified lipids) was produced from arterial blood, saline, and tritium-labeled triolein. The phantom was infused into the cardiopulmonary bypass circuit. Arterial and venous blood samples were taken at short intervals. Tissue samples were taken post-mortem from examined organs and prepared for scintillation counting. Levels of radioactivity were used to measure lipid emboli content in blood and tissue. Results. Emulsified lipid emboli generated a 5-fold higher embolic load in the arterial and a 12-fold higher in the venous circulation, compared with non-emulsified lipid emboli. Emulsified lipid micro emboli resulted in a 2-15-fold higher tissue deposition in investigated organs compared with non-emulsified lipid micro emboli. Conclusions. This study shows that the state of emulsion significantly alter the kinetics and tissue deposition of lipid emboli. Emulsified lipid emboli give higher embolic load in the arterial and venous circulation, and higher tissue deposition versus non-emulsified lipid emboli. In both groups, the embolic load was higher in the arterial circulation than on the venous side

The kinetics of lipid micro-emboli during cardiac surgery studied in a porcine model.

Objective. To study the kinetics of lipid micro-emboli during cardiac surgery. Design. Eleven pigs were studied. Seven of these were put on extracorporeal circulation. A shed blood phantom consisted of blood, saline and radioactive triolein was added to the circuit. Both venous and arterial blood samples were taken at short intervals. Four animals were used to study renal kinetics without extracorporeal circulation. The same kind of shed blood phantom was infused into the ascending aorta. Samples were taken from the renal artery and vein. All samples were analyzed for radioactivity by scintillation counting. Results. A median 130-fold increase in radioactivity was seen in the blood and was quickly eliminated. Systemic first-pass wedging was found to be 62%. The first-pass elimination in the kidney was 77%. No radioactivity was found in urine. Conclusions. This study shows that the turnover of lipid micro-emboli is fast, and that the majority of the emboli are trapped on their first passage through the capillary system. No evidence was found of a renal excretion of these lipid emboli

Blood transfusion after cardiac surgery: is it the patient or the transfusion that carries the risk?

Background: The transfusion of red blood cells (RBCs) after cardiac surgery has been associated with increased long-term mortality. This study reexamines this hypothesis by including pre-operative hemoglobin (Hb) levels and renal function in the analysis. Methods: A retrospective single-center study was performed including 5261 coronary artery bypass grafting (CABG) patients in a Cox proportional hazard survival analysis. Patients with more than eight RBC transfusions, early death (7 days), and emergent cases were excluded. Patients were followed for 7.5 years. Previously known risk factors were entered into the analysis together with pre-operative Hb and estimated glomerular filtration rate (eGFR). In addition, subgroups were formed based on the patients' pre-operative renal function and Hb levels. Results: When classical risk factors were entered into the analysis, transfusion of RBCs was associated with reduced long-term survival. When pre-operative eGFR and Hb was entered into the analysis, however, transfusion of RBCs did not affect survival significantly. In the subgroups, transfusion of RBCs did not have any effect on long-term survival. Conclusions: When pre-operative Hb levels and renal function are taken into account, moderate transfusions of RBC after CABG surgery do not seem to be associated with reduced long-term survival

Risks Associated With the Transfusion of Various Blood Products in Aortic Valve Replacement.

Patients undergoing cardiac operations often require transfusions of red blood cells, plasma, and platelets. From a statistical point of view, there is a significant collinearity between the components, but they differ in indications for use and composition. This study explores the relationship between the transfusion of different blood components and long-term mortality in patients undergoing aortic valve replacement alone or combined with revascularization