Impact of Postoperative Hypothermia on Outcomes in Coronary Artery Bypass Surgery Patients

Abstract

Objectives: To determine the impact of postoperative hypothermia on outcomes in coronary artery bypass graft surgery (CABG) patients.

Design: A retrospective study was performed on patients who underwent isolated CABG between 2011 and 2014.

Setting: Single-center study at a university hospital.

Participants: All patients who underwent isolated CABG with cardiopulmonary bypass between 2011 and 2014.

Interventions: Patients underwent isolated CABG on cardiopulmonary bypass.

Measurements and main results: Patients were propensity-score matched based on the likelihood of being hypothermic (<36ºC) or normothermic (≥36ºC) on arrival to the cardiac surgery intensive care unit (ICU) from the operating room. Total transfusion requirements, composite in-hospital morbidity and/or mortality endpoint, total hours in the ICU, and length of hospital stay were compared between the 2 groups. Of the 1,030 patients undergoing isolated CABG, 529 (51.3%) were hypothermic on arrival to the ICU. The hypothermic cohort were older, had more females, had lower body mass indices, had lower starting hematocrit values, were cooled to lower temperatures while on cardiopulmonary bypass, and had longer cardiopulmonary bypass runs compared with the normothermic group. Of the 748 patients who were propensity matched, there were no differences in blood and blood product transfusion requirements, mortality and complication rates, time on the ventilator, length of ICU stay, and length of hospital stay between hypothermic and normothermic patients.

Conclusions: Hypothermia at ICU admission after CABG was not associated with increased adverse outcomes, possibly suggesting that complete rewarming before separation from cardiopulmonary bypass may not be essential in all patients.

Keywords: cardiopulmonary bypass; coronary artery bypass grafting; outcomes; postoperative hypothermia.