Beat the heat: Identification and Tx of heat-related illness

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Applied Evidence

Beat the heat: Identification and Tx of heat-related illness

J Fam Pract. 2018 August;67(8):468-472

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References

1. Lipman GS, Eifling KP, Ellis MA, et al. Wilderness Medical Society practice guidelines for the prevention and treatment of heat-related illness: 2014 update. Wilderness Environ Med. 2014;25(4 Suppl):S55-S65.

2. Update: Heat injuries, active component, U.S. Armed Forces, 2014. MSMR. 2015;22:17-20.

3. Gaudio FG, Grissom CK. Cooling methods in heat stroke. J Emerg Med. 2016;50:607-616.

4. Hess JJ, Saha S, Luber G. Summertime acute heat illness in U.S. emergency departments from 2006 through 2010: analysis of a nationally representative sample. Environ Health Perspect. 2014;122:1209-1215.

5. People’s Liberation Army Professional Committee of Critical Care Medicine. Expert consensus on standardized diagnosis and treatment for heat stroke. Mil Med Res. 2016;3:1.

6. Stewart TE, Whitford AC. Dangers of prehospital cooling: a case report of afterdrop in a patient with exertional heat stroke. J Emerg Med. 2015;49:630-633.

7. Chan YK, Mamat M. Management of heat stroke. Trends Anaesthesia Crit Care. 2015;5:65-69.

8. Casa DJ, Armstrong LE, Kenny GP, et al. Exertional heat stroke: new concepts regarding cause and care. Curr Sports Med Rep. 2012;11:115-123.

9. Demartini JK, Casa DJ, Stearns R, et al. Effectiveness of cold water immersion in the treatment of exertional heat stroke at the Falmouth Road Race. Med Sci Sports Exerc. 2015;47:240-245.

10. Casa DJ, McDermott BP, Lee EC, et al. Cold water immersion: the gold standard for exertional heatstroke treatment. Exerc Sport Sci Rev. 2007;35:141-149.

11. Zhang Y, Davis JK, Casa DJ, et al. Optimizing cold water immersion for exercise-induced hyperthermia: a meta-analysis. Med Sci Sports Exerc. 2015;47:2464-2472.

12. DeGroot DW, Kenefick RW, Sawka MN. Impact of arm immersion cooling during ranger training on exertional heat illness and treatment costs. Mil Med. 2015;180:1178-1183.

13. Epstein Y, Druyan A, Heled Y. Heat injury prevention—a military perspective. J Strength Cond Res. 2012;26 (suppl 2):S82-S86.

Cooling techniques for heat stroke

Heat-related illness can affect patients of all ages and levels of physical fitness.

In order to adequately cool a patient suffering from heat stroke, health care providers must create a gradient for heat to escape the body through the skin into the environment by conduction, convection, or evaporation.³ Cooling heat stroke patients to less than 40° C (104° F) within 30 minutes after collapse decreases the fatality rate to almost zero.⁸

CWI comes out on top. CWI, also called an ice-bath, is typically performed in the field. The patient is submerged up to the neck in a tub containing ice and water. Circulating the water and ice mixture helps accelerate cooling.

There have been differences in opinion regarding which cooling method is superior³ (TABLE 1^3,8,9). Traditionally, there were some concerns that CWI might actually increase body temperature via peripheral vasoconstriction and shivering. But current research suggests that for exertional heat stroke, CWI to promote conductive cooling is the most effective strategy.^3,8,10,11 A review of cooling rates in healthy hyperthermic athletes and heat stroke victims showed that ice-water immersion or CWI at 1° to 14° C (35.6°-57.2° F) is superior to all other types of cooling, including ice packs, fans, and partial-body ice-water immersion.¹⁰

Furthermore, a 2015 meta-analysis looking at optimal procedures for cooling found that CWI cooled patients twice as fast as passive cooling (without any treatment).¹¹ When cooling with CWI, core temperature drops about 0.2° C/min (0.36° F/min).¹⁰ Therefore, the temperature can be expected to drop about 1° C (1.8° F) for every 5 minutes of immersion. When unable to monitor a rectal temperature continuously, 10 to 15 minutes of immersion should get most patients below 40° C (104° F).

Extremity cooling. While CWI is the standard for cases of exertional heat illness, whole-body immersion is not always possible. In such cases, extremity cooling can be an effective body cooling method for exertional heat-related illness.¹² Research has shown evaporative and convective cooling methods to have benefits for nonexertional heat-related illnesses.^3,8,9 These methods usually involve directing air currents over exposed skin and spraying water on the affected individual.³

Contine to: Guidlines for transport

Beat the heat: Identification and Tx of heat-related illness

References

Cooling techniques for heat stroke

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