Background: Even though the physiological derangements caused by hypothermia are well described, there is no consensus about its impact on postoperative outcomes. The aim of this study is to assess the effect of postoperative hypothermia on outcomes after off-pump coronary artery bypass surgery.
Methods: A total of 1979 patients undergoing isolated off-pump coronary artery bypass surgery in a single center in the period 2007-2018 were classified according to their axillary temperature measurement at intensive care unit admission postoperatively to either hypothermic (<36°C) or normothermic (≥36°C). Between-group differences on baseline characteristics and postoperative outcomes were assessed before and after propensity score matching.
Results: Data analysis showed that 582 patients (29.4%) were hypothermic (median temperature 35.5°C) and 1397 patients (70.6%) were normothermic (median temperature 36.4°C). Using propensity score matching, 567 patient pairs were created. Patients with hypothermia exhibited a higher rate of postoperative transfusion of at least three red cell concentrate units (14.3% vs 9%, p = 0.005), a longer intubation duration (median duration, 6 vs 5 h, p < 0.0001), and a longer intensive care unit stay (median stay, 1.6 vs 1.3 days, p = 0.008). There was no difference in reoperation for bleeding, renal replacement therapy, infections, and mortality between the two groups.
Conclusions: Even though associated with a higher blood transfusion requirement and a slightly longer intensive care unit stay, mild postoperative hypothermia was not associated with a higher morbidity and mortality.
Keywords: Hypothermia; coronary artery bypass grafting; critical care outcomes; off-pump surgery; propensity matching; statistics.