The impact of blood conservation on outcomes in cardiac surgery: is it safe and effective?

Abstract

Background: Increasing evidence shows that perioperative blood transfusion in cardiac surgery is associated with increased postoperative morbidity and mortality and decreased long-term survival. Tolerance of "permissive anemia" is an important element of perioperative blood conservation strategy. The safety of tolerating perioperative anemia has been a significant deterrent for widespread application of blood conservation. This study examines whether blood conservation is equally safe or superior to the common practice of transfusion in cardiac surgery.

Methods: The total study population consisted of 32,449 patients who underwent isolated coronary artery bypass surgery from June 2000 until December 2004 with complete data from 17 institutions in the State of New Jersey. Englewood Hospital and Medical Center (EH) has a well-established blood conservation program. Five hundred eighty-six EH patients (blood conservation cohort) were compared with a propensity score-matched cohort of 586 patients from the other New Jersey institutions (OH-M) representing the common practice of transfusion. Outcomes were classified as very serious complications, serious complications, or neither (no very serious complication or serious complication). Analysis consisted of McNemar tests and multiple logistic regression.

Results: Fewer patients were transfused at EH compared with OH-M (10.6% versus 42.5%; p < 0.0001). Englewood Hospital had 5 (0.8%) deaths versus 15 (2.5%) in the OH-M group (p = 0.02). Of the EH patients, 11.1% experienced a very serious complication or serious complication versus 18.7% in the OH-M cohort (p = 0.0002). Transfusion was associated with an increased risk of an adverse outcome in both cohorts (EH: odds ratio, 7.3; 95% confidence interval, 3.7 to 14.4 versus OH-M: odds ratio, 4.6; 95% confidence interval, 2.8 to 7.7).

Conclusions: Blood conservation is safe and effective in reducing transfusions. Tolerance of perioperative anemia, which is one of the main components of blood conservation, does not increase the risk of complications or death in cardiac surgery. Avoidance of transfusion reduces the risk of complications. This study further solidifies the relationship between transfusion and adverse outcome in cardiac surgery.