Authors: Huang R et al.
Journal of Clinical Anesthesia, 2025 DOI: 10.1016/j.jclinane.2025.112049
Summary
This multicenter retrospective cohort study examined whether extreme temperature events—either heat waves or cold spells—affect the risk of intraoperative hypotension (IOH) in patients undergoing major surgery. The dataset included 276,515 patients treated between 2015 and 2023 at three large academic centers. Temperature extremes were defined using percentile-based thresholds over the 30 days prior to surgery. IOH was defined as mean arterial pressure below 65 mmHg for at least 10 minutes.
Among the cohort, 48,023 patients were exposed to heat waves, 42,615 to cold spells, and 185,877 had no temperature-extreme exposure. Heat waves were associated with a modest reduction in the risk of IOH ≥10 minutes, with an adjusted odds ratio of 0.80. Conversely, cold spells were associated with an increased risk, especially when defined by the most extreme thresholds (2.5th percentile for at least 4 days), where the adjusted odds ratio rose to 1.31. The duration of hypotension also increased with colder conditions. A spline analysis showed nonlinear relationships between 30-day mean temperature and IOH duration, but the overall magnitude of effect remained small.
Although statistically significant, the overall clinical effect size was limited: the full difference in IOH duration across average temperatures from 0 to 30°C was only about 4 minutes. This suggests that ambient environmental temperature contributes physiologically but is far less influential than major patient- or anesthesia-related risk factors.
What You Should Know
• Analysis of more than 276,000 surgeries across three academic centers.
• Heat waves modestly reduced the risk of IOH lasting ≥10 minutes.
• Cold spells increased the risk, with more extreme cold producing stronger effects.
• Temperature effects were real but small in magnitude compared to clinical risk factors.
• Results suggest environmental temperature may play a physiologic role in perioperative blood pressure regulation.
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