Treating Exertional Heat Stroke in the Field
- 4 days ago
- 4 min read
We've detailed issues with Australian recommendations for Exertional Heat Stroke (EHS) treatment, and summarised evidence for alternatives to the commonly recommended application of cold compresses on the shallow arteries in this 2019 paper (Brearley, 2019). In short, rotating cold compresses on the shallow arteries (Figure 1) does not remove adequate body heat to rapidly lower the elevated core temperature associated with EHS. In their 2009 review, McDermott et al. stated "the use of ice packs or ice bags for the treatment of EHS should be discontinued, because the extraction of heat from the body is ineffective for the body temperatures typically associated with EHS".
Figure 1. An illustration of the application of ice packs to the shallow arteries. This method provides unacceptably low cooling rates for treatment of exertional heat stroke
Of the cold compress alternatives, cold water immersion is considered the gold standard, with rotation of cold, wet towels (ice towels) over the entire body regarded as an inferior, yet, effective EHS treatment. Importantly, the ice towels are considered a feasible option for use by workers in remote settings, requiring only an ice box/esky and access to ice, water and cotton towels or similar. Since the outcome from EHS is dependent upon the duration and severity of hyperthermia, medical treatment seeks to minimise the area under the core temperature curve to ensure survival and prevent long-term medical complications. Returning core temperature to less than 39ºC within the 30 minute treatment window or 'golden half hour' post collapse is the objective here.
Based upon the evidence, rotation of ice towels over the entire body is an effective treatment due to reported cooling rates of 1.1ºC per 10 minutes (Table 1). Note that time to return core temperature to 39ºC will vary with severity of EHS (peak core temperature). For severe EHS cases (>41.5ºC), a core temperature decrease of ~3ºC is required within 30 minutes of collapse.
Cooling Modality | Cooling Rate (°C/10 mins) | Reference |
Ice Water Immersion (2°C) | 3.50 | Rogerson and Brearley, 2024 |
Tarp Assisted Cooling with Oscillation (9.2°C) | 1.70 | Proulx et al., 2022 |
Ice Towels/Sheets | 1.60 | DeGroot et al., 2023 |
Ice Towels | 1.10 | Armstrong et al., 1996 |
Combined Cooling * | 0.36 | Kielblock et al., 1986 |
Passive Rest (underwear only) | 0.27 | Kielblock et al., 1986 |
Passive Rest (insulated clothing) | 0.04 | Brearley et al., 2023 |
* Cold packs on groin, neck, and axillae plus splashing body with water while evaporating with compressed air | ||
Table 1. Core temperature cooling rates for selected cooling modalities
Initially, the response to ice towels as an EHS field treatment was mixed, with many organisations stating they would defer choice of treatment to their contracted medical provider. The key point here is that for workers in remote settings and/or on sites remote from facilities, professional medical assistance may not be available within the 30 minute window, even when stationed on-site. Further, the stated 30 minute window does not refer to the time permitted to initiate cooling, rather, it's the time limit to have achieved a substantial core temperature reduction (<39ºC). Hence, the outcome of EHS treatment in remote settings is more likely dependant upon co-workers provision of effective first aid, inclusive of cooling, while medical assistance is en route.
In conjunction with Dr Shane Rogerson of Energy Queensland (Rogerson and Brearley, 2024), we describe the practicality of the ice towel method in an industrial setting (~4000 field workers distributed throughout QLD), where criteria for use include cost effectiveness, portability, scalability, and implementation by a single worker under the stress of an emergency. The paper also describes the emergency application of the ice towel method for a worker suffering suspected EHS on a remote job site, while awaiting paramedics. For this work, Energy Queensland won the Best Solution of a Workplace Health and Safety Risk award at the 32nd Annual National Safety Awards of Excellence (2025). Development and implementation of this technique is summarised in a 2min video, authored by Dr Rogerson (see below).
References
Armstrong LE, Crago AE, Adams R, Roberts WO, Maresh CM. Whole-body cooling of hyperthermic runners: Comparison of two field therapies. Am J Emerg Med. 1996;14:355-8
Brearley M. Are Recommended Heat Stroke Treatments Adequate for Australian Workers? Annals of Work Exposures and Health. 2019, 63:263-266
Brearley M, Berry R, Hunt AP, Pope R. A Systematic Review of Post-Work Core Temperature Cooling Rates Conferred by Passive Rest. Biology. 2023;12:695
DeGroot DW, Henderson KN, O’Connor FG. Cooling modality effectiveness and mortality associate with prehospital care of exertional heat stroke casualities. J Emerg Med. 2023;64:175-80
Hosokawa Y, Adams WM, Belval LN, Vandermark LW, Casa DJ. Tarp-Assisted Cooling as a Method of Whole-Body Cooling in Hyperthermic Individuals. Ann Emerg Med. 2016;69:347-52
Kielblock AJ, Van Rensburg JP, Franz RM. Body cooling as a method for reducing hyperthermia. An evaluation of techniques. S Afr Med J. 1986;69, 378-80
McDermott BP, Casa DJ, Ganio MS, Lopez RM, Yeargin SW, Armstrong LE, Maresh CM. Acute whole-body cooling for exercise-induced hyperthermia: a systematic review. J Athl Train. 2009;44(1):84-93
Proulx CI, Ducharme MB, Kenny GP. Effect of water temperature on cooling efficiency during hyperthermia in humans. J Appl Physiol. 2002;94:1317-23
Rogerson S, Brearley M. Suspected exertional heat stroke; A case study of worker cooling in a hot and humid field environment. Work. 2024;79(4):2103-08
