Introduction: We sought to determine the rate of cooling via a novel water ice therapy (WIT) as an alternative to cold-water immersion for the acute treatment of exertional heat stroke (EHS).
Methods: Observations were made at the 2004-2008 Marine Corps Marathons (mean +/- SD: 16.3 +/- 4.9 degrees C dry bulb, 32 +/- 6% RH). Nine (seven men, two women) EHS patients (33 +/- 6 yr of age; 268 +/- 54 min average race time for six who finished) were observed during on-site treatment. Patients were treated while lying supine on a porous stretcher resting on a tub filled with cold water (approximately 10-12 degrees C). Medical personnel monitored T(re), doused the patient with water and massaged major muscle groups with ice bags until T(re) decreased to 38.9 degrees C. Patients were not immersed in water. Serial T(re) and time were used to calculate cooling rates.
Results: Final T(re) (39.12 +/- 0.63 degrees C) was significantly lower than initial T(re) (41.43 +/- 0.71 degrees C, P < 0.05). Cooling rates were 0.13 +/- 0.04 degrees C min(-1). The decrease in T(re) for the initial 6 min of WIT (0.38 +/- 0.13 degrees C) was significantly less than for the subsequent 6-min time period (1.31 +/- 0.34 degrees C, P < 0.001). Cooling rates for these time periods were significantly different (0.06 +/- 0.02 degrees C x min(-1) and 0.22 +/- 0.06 degrees C x min(-1), respectively, P < 0.05). Initial T(re) was not correlated with overall cooling rate (r = 0.434, P = 0.244), or total cooling time required (17 +/- 4 min; r = 0.207, P = 0.593). Survival rate was 100%.
Conclusion: WIT provided cooling rates that were 70% as effective as those published for cold-water immersion with 8 degrees C water (0.19 degrees C x min(-1)) and resulted in 100% patient survival.