Intraoperative lactate level correlated with the length of hospital stay in patients with intraoperative hypothermia

This study aims to explore potential biomarkers correlated with the clinical outcome only in patients with intraoperative hypothermia undergoing cardiac surgery. The clinical data of patients with or without intraoperative hypothermia, and 8 blood indicators both in preoperative and intraoperative periods, were obtained from the Medical Information Mart for Intensive Care-IV database. The associations of indicators with the length of hospital stay (LOS) were explored in non-hypothermia and hypothermia groups, respectively. The key indicator showing the association only in hypothermia groups was selected for further analysis. The detailed association between the key indicator and LOS was further determined by a series of analyses, including restricted cubic spline, generalized additive model, generalized linear regression, trend regression, threshold effects analysis, and quartile regression. Their clinical value was explored by the receiver operating characteristic analysis and decision curve analysis. Among 16 indicators, only the intraoperative lactate was identified to correlate with the LOS in patients with hypothermia rather than normal group (all P < .05). Lactate showed a positive and nonlinear association with LOS (all P < .05), and their association was especially observed when log-lactate > 2.420 (all P < .05). Quartile regression showed that the associations of lactate with LOS quartiles from 40% and 80% were stably increased when log-lactate > 2.420 (all P < .05). However, no association was observed in any analyses when log-lactate ≤ 2.420. We also confirmed the favorable prediction performance and clinical net benefit of lactate on the LOS. Intraoperative lactate is significantly associated with the LOS of patients with hypothermia and is a useful biomarker.