| Methods |
The efficacy of four different blood conservation techniques in decreasing allogeneic blood transfusion in different cardiac operations were studied in 100 patients undergoing myocardial revascularisation. Method of randomisation and allocation concealment was not described. |
| Participants |
100 patients undergoing myocardial revascularisation were randomly assigned to one of four groups:
Group 1 (Control group): n=25; mean (sd) age = 56.0 (6.6) years Group 2 (Intra‐operative autotransfusion group): n=25; mean (sd) age = 54.1 (6.8) years Group 3 (Acute normovolaemic haemodilution + intra‐operative autotransfusion group): n=25; mean (sd) age = 55.0 (9.4) years Group 4 (Acute normovolaemic haemodilution + intra‐ and post‐operative autotransfusion group): n=25; mean (sd) age = 55.7 (6.3) years
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| Interventions |
Group 1: patients received unprocessed oxygenator blood after the termination of extracorporeal circulation (ECC). Group 2: the blood remaining in the oxygenator after ECC was processed to packed cells with a cell separator (Haemonetics Cell Saver) and re‐transfused until the end of the operation. Group 3: after the induction of anaesthesia and before the start of the operation, isovolumetric hemodilution (harvesting of 10ml/kg autologous blood) was performed under electrocardiographic and haemodynamic control. The blood loss was replaced with hydroxyethyl starch. After termination of ECC, the blood remaining in the oxygenator was processed by a cell separator. The preoperatively drawn blood and the packed cells were retransfused before the end of the operation. Group 4: patients in Group 4 were managed as in Group 3. In addition, the shed mediastinal blood was retransfused in the Intensive Care Unit (ICU). The cardiotomy reservoir of the heart lung machine was used to collect this blood. The drained blood was retransfused intermittently according to the circulatory state of the patient and when at least 250ml of blood had been collected in the reservoir. The last retransfusion was performed 6 hours post‐operatively. |
| Outcomes |
Outcomes reported: amount of blood re‐transfused from the cell saver, amount of allogeneic blood transfused, number of patients transfused allogeneic blood, complications, mortality, ICU length of stay, blood loss, re‐exploration for bleeding, operation time, haematological variables, Hct levels. |
| Notes |
Transfusion threshold: in all patients signs of hypovolaemia and haematocrit values below 30% were indications for allogeneic blood transfusion. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Method used to generate allocation sequences was not described. |
| Allocation concealment (selection bias) |
Unclear risk |
Method used to conceal treatment allocation was unclear. |
| Blinding (performance bias and detection bias)
All outcomes |
High risk |
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