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heat illness

Heat illness treatment

Immersion in iced water is the most effective first-line treatment for exercise-related heat stroke, according to new UK research (‘Cooling methods used in the treatment of exertional heat illness’, British Journal of Sports Medicine 2005; 39:503-507).

Exertional heat illness – or heat stroke – typically affects young athletes or military personnel who are pushed to their physical limits and become dangerously ill as a result of inability to dissipate the heat produced by exercise. Unlike environmental heat illness, which is associated with high external temperatures, the exertional variety can occur any time anywhere, since it is a reflection of intrinsic heat production rather than climate. While there are known risk factors, including dehydration, illness, lack of sleep, alcohol ingestion, over-dressing and poor cardiovascular fitness, these are not always present, and the reason why one person is affected rather than another is not always understood.

Exertional heat stroke is life threatening, and the evidence suggests that a rapid reduction of core body temperature is the key to survival. What is less clear, though, is which is the best method of body cooling.

Dr Jason Smith of Derriford Hospital in Plymouth, UK, set out to answer this question with an examination and appraisal of the available literature on the subject, stretching back as far as 1966. In the end, 17 papers were included in his analysis, focusing on one or more of the following cooling techniques.

  • Body immersion in iced water.
  • Evaporative cooling – spraying water over the patient and using fans to facilitate evaporation and convection.
  • Immersing hands and forearms in cold water.
  • Use of ice or cold packs in the neck, groin and armpits.
  • Invasive methods – iced gastric, bladder or peritoneal lavage.
  • Chemically assisted cooling with a drug called dantrolene, which reduces the rate of muscle contraction by blocking calcium release.

Dr Smith concludes from his review that, after an initial assessment of airway, breathing and circulation, and measurement of rectal temperature, ‘it would appear that immersion in iced water is the most effective method of whole body cooling and should be used where possible’.

He acknowledges, however, that this treatment may not always be practical from a logistic or clinical perspective and may be dangerous in patients with reduced consciousness in the absence of intensive care facilities.

If immersion is unavailable or inappropriate, a combination of other techniques may be used to facilitate rapid cooling, although there is no evidence to support the use of dantrolene in these circumstances.

He calls for further research, including a randomised trial comparing immersion and evaporative therapy in heat stroke patients.

heat illness