Shackleton Department of Anaesthesia, Southampton General Hospital, Southampton, UK
Introduction
The reduction of autologous blood transfusion is a national priority. The use of ANH as a blood conservation strategy remains controversial and under-investigated [1]. A recent paper [2] concluded that ANH should be avoided in patients with critical coronary stenosis or moderate-to-poor left ventricular function. There are no randomized controlled studies of the safety of ANH.
Objectives
To investigate the safety of ANH using continuous Holter electrocardiography monitoring, serial analysis of daily postoperative electrocardiography, and by the use of troponin I levels.
Methods
Patients presenting for elective coronary artery bypass surgery were randomized into a control or an ANH group. All patients had a four-lead Holter electrocardiography monitor attached 1 h before surgery. After a standard anaesthetic induction, patients in the ANH group had 10 ml/kg blood removed while being maintained within 20% of their baseline blood pressure. This blood was rein-fused after cardiopulmonary bypass. Troponin I levels were taken preoperatively, prebypass and at 24 h. All patients had daily postoperative electrocardiography analysis.
Results
The results are shown in Table
ANH
Control
Variable
(
(
Age (years)
64.2 ± 7.28
64.7 ± 8.61
0.880
Parsonnet score
5.39 ± 4.05
7.13 ± 5.84
0.288
Ischaemic burden
20.16 ± 41.7
26.9 ± 97.1
0.600
New ECG changes
2/18
7/22
Troponin I 24 h (μg/l)
2.39 ± 2.26
4.28 ± 3.59
0.064
Bypass time (min)
73.01 ± 20.76
73.74 ± 16.33
0.907
X-clamp time (min)
44.11 ± 14.12
43.44 ± 9.42
0.855
Values are expressed as mean ± standard deviation, unless otherwise stated. ECG, electrocardiography.
Conclusion
ANH is safe. There is no evidence of an additional ischaemic burden after haemodilution.