Determinants of transfusion decisions in a mixed medical-surgical intensive care unit: a prospective cohort study

For reasons unknown, a restrictive transfusion policy of red blood cells (RBC) is only gradually being implemented by Intensive Care Unit (ICU) physicians, resulting in a large variation in transfusion practice. Insight into physicians' transfusion decisions may aid efforts to restrict transfusion practice.

In a prospective cohort study, transfusion triggers were determined in patients consecutively admitted to an ICU during a 10-week period. Using a questionnaire, the reasons why ICU physicians transfused RBC were evaluated.

Among 310 admissions, 90 patients (29%) received a RBC transfusion. Eighty-one of these 90 patients were included in this analysis. RBC were transfused at a mean haemoglobin (Hb) level of 7.4+/-1.1 g/dL. Residents transfused RBC at a higher Hb level compared to senior staff (7.7+/-1.0 versus 6.9+/-1.3, respectively; p<0.05). The most important reason for physicians to transfuse RBC was the suspicion of bleeding. Age and coronary ischaemia were the predominant reasons for transfusing RBC in 4% and 12% of cases, respectively. The average order for RBC transfusion was four units. Of each order, 38% of the units were not administered.

RBC transfusion decisions are predominantly based on Hb levels rather than on patients' characteristics. Residents transfuse at a higher Hb level compared to more experienced physicians. The major determinant for physicians to transfuse RBC is bleeding. However, the majority of patients were transfused in the absence of bleeding, and many of these patients received multiple units. The need for RBC may be overestimated, resulting in wasted orders.