Surface Temperatures of Self-Warming Chemical Blankets Exceed Established Safety Thresholds: A Standardized Bench-Testing Study.

Abstract

Introduction: Self-warming chemical blankets are widely deployed in military, prehospital, and hospital settings as a power-independent warming solution. Despite widespread use, no harmonized safety standard governing surface temperature limits for this device class is known to exist, and independent bench-testing data are sparse. This study aimed to characterize the thermal performance and safety profiles of commercially available self-warming chemical blankets and evaluate their suitability for use in military, prehospital, and perioperative contexts.

Materials and methods: Four self-warming chemical blanket devices were subjected to standardized laboratory bench testing following the IEC 60601-2-35:2021 framework as an analogical reference standard. Twelve-channel K-type thermocouple arrays and infrared thermography recorded surface temperature distribution over time. Key outcomes included time to 40°C, maximum recorded surface temperature, surface temperature uniformity, and sustained high-temperature exposure duration.

Results: The Hypothermia Prevention and Management Kit (HPMK) Full Body and HPMK-I Full Body Self-Heating Blankets reached maximum recorded temperatures of 69.1°C and 69.0°C, respectively, and the Ready-Heat Full Body Self-Heating Blanket reached 68.7°C, all substantially and persistently exceeding established burn thresholds for more than 12 hours. The Mölnlycke Barrier EasyWarm required over 81 minutes to reach peak temperature, did not achieve 40°C within clinically relevant timeframes, and also exceeded burn thresholds under prolonged contact. No device demonstrated simultaneous rapid attainment of therapeutic temperature and maintenance of safe surface temperatures.

Conclusions: Commercially available self-warming chemical blankets exhibit a dual failure: they are too slow to provide therapeutic warming within the acute treatment window and generate surface temperatures consistent with serious burn risk under prolonged contact, particularly in patients with impaired peripheral circulation or reduced consciousness. The absence of a dedicated safety standard for this device class means that devices generating temperatures far above recognized burn thresholds are fully compliant with current regulatory requirements. The evidence base supporting clinical use of these devices is thin, and these findings are corroborated by burns reported to national device-safety databases. Urgent development of fit-for-purpose safety and performance standards is warranted, alongside review of the guideline endorsement and procurement that sustain the use of these devices.