A randomized, controlled trial of blood conservation technologies in elective coronary artery bypass surgery

Objectives

To assess the effectiveness of two mechanical methods of blood conservation in reducing the exposure to transfusion of allogenic red blood cells or any blood products during elective coronary artery bypass (CAB) surgery.

Introduction

The reduction of allogenic blood transfusion is a national priority. Acute Normovolaemic Haemodilution (ANH) and Intraoperative Cell Salvage (ICS) are two mechanical strategies used to achieve this. A recent meta-analysis of effectiveness of ICS [1] found no trials in cardiac surgery that employed these devices intraoperatively. ANH trials in cardiac surgery have been equivocal as to their benefit [2].

Methods

After local ethical approval and informed consent, 252 patients for routine CAB surgery were randomised into either a control group (who received a standard cardiac anaesthetic and operation), or an ICS group (where an ICS device was used during the operation and the residual circuit volume washed), or an ANH group (where 10 ml/kg of blood was extracted post induction and replaced with colloid, in addition to the use of an ICS device used as above). Outcome measures were proportions of patients exposed to allogenic blood or blood products and total units used. Standard transfusion thresholds were employed. Data was analysed using a non-parametric ANOVA.

Results

There were no significant differences between the three groups with respect to age, weight, Parsonnet score, bypass and cross-clamp times. Hospital length of stay, and median and total mediastinal drainage were similar across groups. Outcome measures (exposures, units of blood and P values) are shown in Table 1.

Table 1 Outcome measures

Conclusions

In elective CAB surgery, ICS significantly reduces the risk of exposure to allogenic blood and blood products. ANH does not confer any additional benefit.