Changing the practice of blood transfusion in intensive care

Optimal red blood cell (RBC) transfusion in critically ill patients remains controversial and, amongst other complications, transfusion induced impaired immune response has been postulated. We modified our transfusion practice in ICU after Herbert et al.'s Canadian multi-centre trial, compared a liberal (10-12 g/dl) to restrictive (7-9 g/dl) RBC transfusion strategy [1]. They concluded that restrictive RBS usage was at least equivalent, and possibly superior, to a more liberal transfusion strategy.

Aim

Before and after change in transfusion practice, we documented ICU RBC usage, admission severity of illness (APACHE II), and ICU and hospital mortality.

Method

Retrospective study of RBCs transfused in two 6 month periods (135 patients in 1997 and 171 patients in 1998).

Results

Demographics were similar in the two groups. Average admission Hb in 1997 was 11.3 g/dl and in 1998 10.8 g/dl. Discharge Hb in 1997 was 10.9 (g/dl) and 10.0 (g/dl) in 1998. Average APACHE II was 20.5 in 1997 and 20.4 in 1998. ICU mortality was 28.8% in 1997 compared to 29.8% in 1998. Hospital mortality in 1997 was 34.8% compared to 37.4% in 1998. The average length of ICU stay in 1997 was 6.5 days compared with 5.6 in 1998. Standardised mortality ratio was 1.0 in 1997 and 1.02 in 1998. 586 RBC units were transfused in 1997 compared to 483 in 1998. This equates to 4.3 units per patient in 1997 and 2.8 units per patient in 1998 (35% reduction in RBC usage). 30.1% of patients received no blood in 1997, compared to 51.7% in 1998. In untransfused surgical patients in 1997 average APACHE II was 8.6 and in untransfused medical patients it was 18.5, compared to 12.2 and 20.3 respectively in 1998. In 1997 the medical patients received 230 RBC units, compared to 200 in 1998. 68.4% of medical patients were transfused in 1997 versus 60.5% in 1998. Average APACHE II for transfused medical patients in 1997 was 26.5 versus 29.1 in 1998 and for untransfused patients 18.5 in 1997 versus 20.3 in 1998. The surgical patients received 356 RBC units in 1997 compared to 283 in 1998. 20% of vascular patients remained untransfused in 1997 versus 39.3% in 1998. Average APACHE II of vascular patients was 13.3 in 1997 (average total surgical APACHE II 18.1) versus 15.0 in 1998 (average total surgical APACHE II 17.6). The average admission and discharge haemoglobins of vascular patients were 12.3 g/dl and 10.1 g/dl in 1997 versus 10.1 and 9.9 g/dl in 1998.

Conclusion

Restrictive blood transfusion strategy appears to be safe practice, even in patients with relatively high APACHE II scores. There was a reduction of 106 units of RBCs in 1998 compared to 1997. This translates into a considerable financial saving for the hospital (approximately £17,000 p.a.) and a better balanced use of vital blood products, in a time of national shortage.