Characteristics of Intraoperative Hypothermia and Rewarming Responses in Elderly Patients Undergoing General...

This study aimed to investigate the characteristics of intraoperative hypothermia (IH) and evaluate the efficacy of rewarming interventions in elderly patients undergoing general anesthesia, with particular emphasis on the influence of different traditional Chinese medicine (TCM) constitutions.

A two-phase study was conducted. The first phase involved a retrospective analysis of 500 elderly patients undergoing general anesthesia to identify risk factors associated with IH. The second phase consisted of a randomized controlled trial comparing rewarming strategies in 80 elderly patients with IH.

Between March and August 2022, data from 500 elderly patients at the First Affiliated Hospital of Guangzhou University of Chinese Medicine were retrospectively reviewed and categorized into IH and non-IH groups based on the occurrence of hypothermia during surgery. Baseline characteristics were collected and analyzed using univariate and multivariate logistic regression models. A predictive model for IH was developed and validated through receiver operating characteristic (ROC) curve analysis. From September to October 2022, 80 elderly patients with confirmed IH were prospectively enrolled and randomly assigned to either a control group or an observation group to compare the effectiveness of rewarming interventions; the observation group received active warming via an inflatable warming blanket.

IH was prevalent among elderly surgical patients under general anesthesia, affecting 36.0% of the cohort. Patients with specific TCM constitutions - particularly Qi Yang, or blood deficiency - along with those exhibiting a low body mass index (<24 kg/m²) and preoperative core body temperature below 37.0°C, were at significantly higher risk. Factors such as major surgical procedures, low operating room temperatures (<24°C), prolonged anesthesia duration (≥2 h), and high intraoperative fluid administration (≥2000 ml) were independently associated with increased IH risk (odds ratios ranging from 3.258 to 12.305). The timely application of inflatable warming blankets significantly reduced both rewarming time and postoperative shivering incidence (5.0% vs. 22.5% in controls), demonstrating its effectiveness in managing IH.

IH is highly prevalent among elderly patients undergoing general anesthesia, particularly among individuals with certain TCM constitutions, low BMI, and reduced preoperative core temperature. Several perioperative factors significantly increase the likelihood of IH. Timely intervention with inflatable warming blankets proves to be an effective and clinically relevant strategy for mitigating IH and improving thermal management in this vulnerable population.