Cardiopulmonary exercise testing before and after blood transfusion: a prospective clinical study.

BACKGROUND Cardiopulmonary exercise testing (CPET) is used to risk-stratify patients undergoing major elective surgery, with a poor exercise capacity being associated with an increased risk of complications and death. Patients with anaemia have a decreased exercise capacity and an increased risk of morbidity and mortality after major surgery. Blood transfusion is often used to correct anaemia in the perioperative period but the effect of this intervention on exercise capacity is not well described. We sought to measure the effect of blood transfusion on exercise capacity measured objectively with CPET. METHODS Patients with stable haematological conditions requiring blood transfusion underwent CPET before and 2-6 days after transfusion. RESULTS Twenty patients were enrolled and completed both pre- and post-transfusion tests. The mean (sd) haemoglobin (Hb) concentration increased from 8.3 (1.2) to 11.2 (1.4) g dl(-1) after transfusion of a median (range) of 3 (1-4) units of packed red cells. The anaerobic threshold increased from a mean (sd) of 10.4 (2.4) to 11.6 (2.5) ml kg(-1) min(-1) (P=0.018), a mean difference of 1.2 ml kg(-1) min(-1) (95% confidence interval (CI)=0.2-2.2). When corrected for the change in Hb concentration, the anaerobic threshold increased by a mean (sd) of 0.39 (0.74) ml kg(-1) min(-1) per g dl(-1) Hb. CONCLUSIONS Transfusion of allogeneic packed red cells in anaemic adults led to a significant increase in their capacity to exercise. This increase was seen in the anaerobic threshold, and other CPET variables.