Impact of autotransfusion after coronary artery bypass grafting on oxygen transport.

BACKGROUND: Autotransfusion of shed mediastinal blood after coronary artery bypass grafting (CABG) has been shown to reduce the requirement for allogeneic blood. We have previously demonstrated in non-randomized studies that the oxygen capacity of shed mediastinal blood is similar to the patient's circulating blood and better than stored allogeneic blood. Therefore, we wanted to examine the influence of autotransfusion of shed mediastinal blood on oxygen transport capacity in patients undergoing CABG. METHODS: A prospective, randomized, controlled study involving 120 patients having elective, uncomplicated CABG was performed. The autotransfusion group received transfusion of shed mediastinal blood for 18 h. Both groups received allogeneic red cells if their hemoglobin concentration decreased below 5 mmol/L. Red blood cell 2,3-diphosphoglycerate (2,3-DPG) was measured preoperatively and at intervals up to the hospital discharged. Hemodynamic measurements as well as blood gas and hemoglobin measurements from samples of arterial and mixed venous blood were used for calculation of oxygen transport capacity. RESULTS: During the autotransfusion period only 2 patients (4%) in the autotransfusion group required allogeneic blood compared to 11 patients (20%) in the control group. The 2,3-DPG levels in the autotransfusion group were unchanged before and after autotransfusion (4.4 vs. 4.3 mumol/ml erythrocyte). In the control group, 2,3-DPG levels decreased from 4.3 to 3.9 mumol/ml erythrocyte during the same period. There were no differences in the other measured parameters for oxygen transport capacity between the groups. CONCLUSION: Autotransfusion of shed mediastinal blood conserves the 2,3-DPG level of the red blood cells, while transfusion of stored blood leads to a decrease in 2,3-DPG levels. Autotransfusion had no effect on hemodynamic parameters, oxygen delivery or oxygen extraction.

Cardiac enzymes and autotransfusion of shed mediastinal blood after myocardial revascularization.

BACKGROUND: Autotransfusion of shed mediastinal blood reduces blood requirement after coronary artery bypass grafting. Recently, two nonrandomized trials indicated that autotransfusion elevates the levels of cardiac enzymes after cardiac operations. METHODS: Prospective, randomized controlled studies involving 120 patients (study A) and 15 patients (study B) having elective uncomplicated coronary artery bypass grafting were performed. Autotransfusion of shed mediastinal blood was performed for 18 hours in the patients allocated to autotransfusion. Serum levels of cardiac enzymes were measured. In study B cardiac enzyme levels in shed mediastinal blood and circulating blood were measured 1 hour postoperatively. RESULTS: Cardiac enzyme levels were significantly elevated in the patients receiving autotransfusion. In patients with a perioperative myocardial infarction. The level of creatine kinase-MB was much higher than in the autotransfused patients without myocardial infarction. The level of cardiac enzymes was higher in shed mediastinal blood compared with circulating blood. CONCLUSIONS: Postoperative autotransfusion of shed mediastinal blood causes elevation of cardiac enzyme levels after coronary artery bypass grafting.

Autotransfusion after coronary artery bypass grafting halves the number of patients needing blood transfusion.

BACKGROUND: Several randomized studies about autotransfusion of shed mediastinal blood in patients undergoing coronary artery bypass grafting have resulted in divergent findings concerning reduction of the need for homologous blood transfusions. Most of these studies used less strict criteria for homologous blood transfusion than applied in daily clinical practice. METHODS: A prospective, randomized, controlled study involving 120 patients having elective, uncomplicated coronary artery bypass grafting was performed. The autotransfusion group received transfusion of shed mediastinal blood for 18 hours. Criteria for homologous blood transfusion were hemoglobin concentration less than 5.0 mmol/L in the intensive care unit and less than 5.5 mmol/L during the rest of the hospital stay. RESULTS: Twenty-eight percent of patients in the autotransfusion group received homologous blood transfusion versus 55% in the control group (p = 0.007). Ninety-five percent of the shed mediastinal blood was transfused. In the autotransfusion group, a total of 26 units of homologous blood was used versus 78 units in the control group (p < 0.001). CONCLUSIONS: Autotransfusion of shed mediastinal blood in patients undergoing elective, uncomplicated coronary artery bypass grafting halves the number of patients needing homologous blood and reduces the amount of homologous blood given.

[Complications of spinal anesthesia compared to general anesthesia. A prospective study of 408 consecutive orthopedic patients]. / Komplikationer ved spinal anaestesi sammenlignet med generel anaestesi. En prospektiv undersøgelse omfattende 408 konsekutive ortopaedkirurgiske patienter.

UNLABELLED: In this prospective study the preoperative risk classification and pulmonary status was compared to postoperative mortality and morbidity, following either spinal or general anaesthesia. We studied 408 consecutive orthopaedic patients. Comparing the anaesthetic methods we found no differences in mortality or in frequency of cardiac complications, while the non-cardiac complications were seen more frequently in patients who had undergone spinal anaesthesia (p < 0.05). Patients from the lower risk groups with a preoperative abnormal pulmonary status had a higher frequency of postoperative pulmonary complications following spinal anaesthesia than following general anaesthesia (p = 0.015). IN CONCLUSION: 1) We find no difference in postoperative mortality depending on the anaesthetic method chosen, 2) the predictive value of the Boston Cardiac Risk index is identical for the two anaesthetic methods, and 3) the anaesthetic method of choice for the pulmonary disabled patient has not yet been established.

[Risk and hemodynamic instability in spinal anesthesia]. / Risiko og haemodynamisk instabilitet ved spinal anaestesi.

We investigated 131 consecutive patients who were submitted to orthopaedic surgical interventions under spinal anaesthesia during a period of 12 months. Prior to operation, all of the patients were classified according to the Boston Cardiac Risk Index. Immediately before operation, approximately 500 ml sodium chloride solution was infused. Patients were registered as haemodynamically unstable when a peroperative fall in the mean arterial pressure of more than 30% occurred or when the systolic blood pressure fell to less than 80 mmHg. In 40 patients, haemodynamically unstable conditions developed peroperatively while 91 were haemodynamically stable. In Boston group III, 67% of the patients were haemodynamically unstable peroperatively which was significantly more than in the Boston group I (25%) and the Boston group II (32%) (p less than 0.005). The postoperative mortality was significantly higher (13%) among the total number of peroperatively haemodynamically unstable patients than among the peroperatively stable patients (3%) (p less than 0.05). In Boston group III, the postoperative mortality was 42% as compared with 1% and 7% in the Boston groups I and II, respectively (p less than 0.05). It is concluded that the risk of fall in blood pressure during spinal anaesthesia may be predicted by the Boston Cardiac Risk Index and that patients who develop haemodynamic instability during spinal anaesthesia have an increased risk of developing complications. These patients should be offered maximal postoperative observation and care.

Postoperative haemodynamics in patients with and without cardiac disease.

The cardiovascular reaction to primarily major vascular surgery was examined in 39 patients without cardiac disease and in 11 patients with cardiac disease. In the immediate postoperative period (24 h), patients without cardiac disease showed significant increases in heart rate and cardiac index and a decreased blood volume. The central pressures were increased during the first postoperative hour. Systemic blood pressure and vascular resistance remained unchanged, or decreased slightly. Postoperative haemodynamics in patients with cardiac disease followed the same trends as in normal patients; there were, however, no significant changes in cardiac index or central pressures, and in general the cardiovascular reaction to operation was less conspicuous than in the group of normal patients. The preoperative haemodynamic differences between the two groups were diminished in the immediate postoperative period because therapy could be guided by measuring central pressures.