Hypothermia, pH, and Postoperative Red Blood Cell Transfusion in Massively Transfused Adult Cardiac Surgery Patients: A Retrospective Cohort Study.

OBJECTIVE

To determine the relationships between hypothermia and pH at surgery end and postoperative red blood cell (RBC) transfusion in massively transfused adult cardiac surgery patients.

DESIGN

Retrospective cohort study.

SETTING

Single tertiary care, academic medical center.

PARTICIPANTS

A total of 395 adult patients having cardiac surgery with cardiopulmonary bypass who were massively transfused during an 8-year period. Patients were excluded if they did not receive an antifibrinolytic drug during surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Body temperature and pH at surgery end were recorded. Postoperative RBC transfusion, a surrogate for postoperative bleeding, was the study's primary outcome. Secondary outcomes were postoperative fresh frozen plasma (FFP) transfusion, postoperative platelet transfusion, reoperation for bleeding, and mortality. Patients with hypothermia did not have more postoperative RBC transfusion (p = 0.56), but patients with acidosis or alkalosis received more RBCs after surgery (p = 0.04). There were no differences in secondary outcomes between groups. In multivariate analysis, both acidosis and alkalosis were independently associated with postoperative RBC transfusion (p = 0.01 and p < 0.0001).

CONCLUSION

Hypothermia at surgery end has no association with postoperative RBC transfusion in massively transfused cardiac surgery patients, but pH derangements are associated with increased postoperative transfusion. Thus, normalization of blood pH may be important in reducing postoperative bleeding in massively transfused cardiac surgery patients.