Characteristics and Risk Factors of Intraoperative Hypothermia in Adults: A Multicenter Prospective Observational Clinical Study

<b>Objective:</b> Intraoperative hypothermia is a common perioperative complication. This large-scale, multicenter, prospective clinical study aimed to delineate the occurrence patterns of intraoperative hypothermia in adults and to identify its major independent risk factors, thereby providing evidence-based support for early clinical risk assessment and intervention. <b>Methods:</b> This study adopted a multicenter, prospective, observational design. Eligible participants were screened based on predefined inclusion and exclusion criteria, and a total of 4516 surgical patients (≥18 years) from 12 tertiary general hospitals across China were ultimately enrolled. Core body temperature was continuously monitored intraoperatively using standardized methods. Data on demographic characteristics, surgical and anesthesia-related parameters, and perioperative temperature management interventions were collected. Patients were stratified into groups according to the presence or absence of hypothermia (core temperature <36.0 °C). Univariate analyses were first conducted to identify associated factors, followed by multivariable logistic regression to determine factors independently associated with intraoperative hypothermia. <b>Results:</b> The overall incidence of intraoperative hypothermia among surgical patients was 23.82%. Hypothermia occurred most frequently in patients with a preoperative baseline core temperature ≤ 35.9 °C (85.93%). Among surgical specialties, hand surgery had the highest incidence of hypothermia (51.35%), and among surgical sites, procedures involving the upper extremities showed the highest rate (35.00%). Multivariable logistic regression analysis identified the following as independent risk factors for intraoperative hypothermia: Type of anesthesia (OR = 1.743, 95% CI: 0.834-3.644), ASA classification (OR = 1.408, 95% CI: 1.197-1.657), Surgical approach (OR = 0.735, 95% CI: 0.577-0.936), Skin disinfection site (OR = 2.024, 95% CI: 1.534-2.670), Volume of cold intravenous fluids infused (mL) (OR = 1.365, 95% CI: 1.140-1.633), Volume of transfused blood (U) (OR = 1.116, 95% CI: 0.807-1.542), Intraoperative blood loss (mL) (OR = 1.252, 95% CI: 0.892-1.756), and Duration of surgery (hours) (OR = 2.014, 95% CI: 1.683-2.411). <b>Conclusions:</b> The incidence of intraoperative hypothermia in adults was relatively high at 23.82% and was observed to be associated with multiple modifiable perioperative factors. These findings support the need to strengthen risk assessment and implement individualized temperature management strategies in clinical practice, with the goal of reducing the risk of intraoperative hypothermia and improving perioperative safety and outcomes.