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J Athl Train. 2010 Sep-Oct;45(5):439-44. doi: 10.4085/1062-6050-45.5.439.

Cold-water immersion and the treatment of hyperthermia: using 38.6°C as a safe rectal temperature cooling limit.

Author information

1
Human and Environmental Physiology Research Unit, University of Ottawa, ON, Canada.

Abstract

CONTEXT:

Cold-water immersion is recommended for the immediate field treatment of exertional heat stroke. However, concerns exist over potential overcooling of hyperthermic individuals during cold-water immersion.

OBJECTIVE:

To evaluate the recommendation that removing previously hyperthermic individuals from a cold-water bath at a rectal temperature (T(re)) of 38.6°C would attenuate overcooling.

DESIGN:

Controlled laboratory study.

SETTING:

University research laboratory.

PATIENTS OR OTHER PARTICIPANTS:

Participants included 6 men and 4 women (age  =  22 ± 3 years, height  =  172 ± 10 cm, mass  =  67.8 ± 10.7 kg, body fat percentage  =  17.1% ± 4.5%, maximum oxygen consumption  =  59.3 ± 8.7 mL·kg(-1)·min(-1)).

INTERVENTION(S):

After exercising at an ambient temperature of 40.0°C for 38.5 ± 9.4 minutes, until T(re) reached 39.5°C, participants were immersed in a 2.0°C circulated water bath until T(re) decreased to either 37.5°C or 38.6°C. Subsequently, participants were removed from the water bath and recovered for 20 minutes at an ambient temperature of 25°C.

MAIN OUTCOME MEASURE(S):

Rectal and esophageal temperatures were measured continuously during the immersion and recovery periods.

RESULTS:

Because of the experimental design, the overall time of immersion was greater during the 37.5°C trial (16.6 ± 5.7 minutes) than the 38.6°C trial (8.8 ± 2.6 minutes) (t(9)  =  -4.740, P  =  .001). During the recovery period after cold-water immersion, both rectal (F(1,9)  =  50.540, P < .001) and esophageal (F(1,6)  =  20.365, P  =  .007) temperatures remained greater in the 38.6°C trial than in the 37.5°C trial. This was evidenced by low points of 36.47°C ± 0.70°C and 37.19°C ± 0.71°C for rectal temperature (t(9)  =  2.975, P  =  .016) and of 35.67°C ± 1.27°C and 36.72°C ± 0.95°C for esophageal temperature (t(6)  =  3.963, P  =  .007) during the recovery period of the 37.5°C and 38.6°C trials, respectively.

CONCLUSIONS:

Immersion for approximately 9 minutes to a rectal temperature cooling limit of 38.6°C negated any risk associated with overcooling hyperthermic individuals when they were immersed in 2°C water.

PMID:
20831387
PMCID:
PMC2938313
DOI:
10.4085/1062-6050-45.5.439
[Indexed for MEDLINE]
Free PMC Article

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