Predictors of Cardiac Surgery Patients Who Tolerate Blood Conservation in Cardiac Surgery

Background: Whether there is a cardiac surgical patient population that does not incur harm from blood conservation is unknown. This study aimed to identify patient characteristics associated with patients who safely tolerate blood conservation.

Methods: We conducted a retrospective review of consecutive patients undergoing isolated coronary artery bypass graft surgery or isolated aortic valve replacement, or concomitant coronary artery bypass graft surgery and aortic valve replacement between 2011 and 2016, during which blood conservation intervention took place. Logistic regression derived from the preintervention cohort was applied to the postintervention cohort to identify patient characteristics associated with those predicted to be transfused in the preintervention era but were not in the postintervention era.

Results: In this series of 2,701 adult patients undergoing cardiac operations, blood conservation intervention in 2014 led to a 52% reduction in red blood cell transfusion. Between preintervention and postintervention cohorts, there was no significant difference in the measured outcomes. A regression model derived from the preintervention cohort was applied to the postintervention cohort to identify predictors of cohort that do not derive benefit from liberal transfusion. This model demonstrated such patient characteristics to be age more than 75 years (odds ratio [OR] 1.71, 95% confidence interval [CI]: 1.09 to 2.68, p = 0.033), body mass index less than 30 kg/m² (OR 1.5, 95% CI: 1.02 to 2.20, p = 0.044), lowest intraoperative hematocrit between 22 and 25 (OR 1.77, 95% CI: 1.16 to 2.68, p < 0.001), and cardiopulmonary bypass use (OR 4.50, 95% CI: 2.25 to 9.01, p < 0.001).

Conclusions: Blood conservation can successfully yield reduction in perioperative blood product use, with associated decrease in the risk of postoperative renal failure. A select patient population who may tolerate blood conservation safely was identified, and that may guide a targeted blood conservation effort.