Intraoperative hypothermia and its clinical outcomes in patients undergoing general anesthesia: National study in China

Abstract

Background/objective: Inadvertent intraoperative hypothermia (core temperature <36°C) is a frequently preventable complication with several adverse consequences. Our study aimed to determine the overall incidence of inadvertent intraoperative hypothermia and its risk factors associated with clinical outcomes in this national survey in China.

Methods: We conducted a national cross-sectional study with 30 days postoperative follow-up from November 2014 through August 2015. A total of 3132 eligible patients underwent general anesthesia were randomly selected from 28 hospitals in the nationwide of China.

Results: The overall incidence of intraoperative hypothermia was as high as 44.3%, in which cumulative incidence rates of hypothermia being 17.8%, 36.2%, 42.5% and 44.1% within 1 h, 2 h, 3 h and 4 h respectively following induction of anesthesia. All patients were warmed passively by covering of surgical draping, sheets or cotton blankets, whereas only 14.2% of patients received active warming with space heaters or electric heater or electronic blankets. Compared to normothermic patients, patients with hypothermia is associated with more postoperative ICU admit, longer PACU and more postoperative hospital days, but no difference in surgical site infection (SSI) rates or 30-day mortality. Several factors were shown to be associated with decreased risk of hypothermia. They are active warming (OR = 0.46, 95% CI 0.26-0.81), BMI ≥ 25 (OR = 0.54, 95% CI 0.45-0.65), higher baseline core temperature (OR = 0.04, 95% CI 0.03-0.06), and higher ambient temperature (OR = 0.83, 95% CI 0.78-0.88). Risk factors associated with an increased risk of hypothermia included major-plus surgery (OR = 1.49, 95% CI 1.23-1.79), and long anesthesia (>2 h) (OR = 2.60, 95% CI 2.09-3.24).

Conclusions: The incidence of intraoperative hypothermia in China is high, and the rate of active warming of patients during operation is low. Hypothermia is associated with more postoperative shivering, increased ICU admissions, and longer postoperative hospital days.

Conflict of interest statement

Competing Interests: MDI0091 was provided by 3M China. This funder did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Five 3M current or former employees, Ziyong Xiang, Shuang Pan, Lujing Zhan, Kai Qiu, and Min Yao, helped conduct this study. Please see detailed information in the section of “additional information”. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1. Change of intraoperative core temperature during operations.

Patients’ core temperature was measured at the tympanic membrane beginning every 15 minutes after the induction of anesthesia until the end of the operation. A total of 3132 subjects were enrolled in the study; each curve represents a connection of 5 percentiles, 25 percentile, 50 percentile, 75 percentile and 95 percentile of core temperature at a specific time point. The time interval is 15 minutes.