Using ice packing and the polar life pod to treat severe hyperthermia

Introduction

Cold water immersion (CWI) is the fastest method of reducing body temperature of exertional heatstroke (EHS) patients. Treatment delays and/or an inability to quickly cool EHS patients with CWI before or while enroute to hospitals are common contributors to EHS morbidity and mortality. CWI in ambulances and emergency departments (ED) is challenging since they often lack CWI equipment (e.g., tubs). Recently, clinicians demonstrated excellent EHS patient outcomes using CWI with body bags (BAGS). However, using BAGS with CWI in ED creates other challenges (e.g., medical staff slipping, drainage). Ice packing with BAGS may quickly reduce body temperature and resolve these issues. We measured rectal temperature (T_REC) cooling rates with three ice masses and no added water in the Polar Life Pod (PLP), a body-bag-like device.

Methods

Twelve subjects (8 males, 4 females; age:22 ± 3y; mass:71.9 ± 10.6 kg; ht.:170.2 ± 7.3 cm) exercised in the heat (wet bulb globe temperature = ∼27 °C) until T_REC was ≥39.75 °C. They laid in PLP while ∼9 kg (SMALL), ∼27 kg (MEDIUM), or ∼ 53 kg (LARGE) of nugget ice was poured into PLP. Cooling stopped when T_REC was 38.25 °C.

Results

T_REC cooling rates increased as ice mass increased (SMALL:0.15 ± 0.05 °C/min; MEDIUM:0.19 ± 0.07 °C/min; LARGE:0.27 ± 0.10 °C/min, P < 0.001). Minimal water was created from ice melting (SMALL: 3.8 ± 1.1 L; MEDIUM: 5.3 ± 2.1 L; LARGE: 4.9 ± 2.2 L, P = 0.07).

Conclusions

Ice packing in the PLP quickly reduced T_REC and resolved many of the challenges of treating EHS in ED and ambulances. The PLP portability, small space footprint, and effectiveness suggest it can be implemented while enroute to ED, potentially reducing the morbidity and mortality caused by lengthy treatment delays.