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Three Part Question

[In adult patients presenting with pyrexia], are [passive cooling methods better than commercial/active cooling methods] for [reducing body temperature]?

Clinical Scenario

A female patient presents at the emergency department, following the apparent ingestion of ecstasy in a night club. She appears confused and severely agitated, with tachycardia and a temperature of 40°C. The patient begins seizing, which is controlled with benzodiazepines, but as her temperature continues to rise, you consider which method may be best for cooling the patient.

Search Strategy

27/06/17
Ovid Embase 1974 to 2017 Week 26
Ovid MEDLINE 1946 to June Week 3 2017
LIMIT to human
(("hyperthermia" or "hyperpyrexia" or "pyrexia" or "exertional heat") and ("active cooling" or "passive cooling" or "ice water" or "cold water" or "fanning" or "arctic sun" or "commercial cooling" or "conventional cooling")).mp.

5/7/17
Cochrane (three separate searches):
• “Cooling”
• “Heat Stroke”
• “Heat stress”

Search Outcome

Embase/Medline: 23 results, 5 relevant to the BET.
Cochrane: 0 relevant results.
One additional paper was by hand searching references.
Six papers were relevant in total.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Y. Zhang et al 2015	Healthy adults subjected to exercise-induced hyperthermia with pre-treatment temperatures above 38.3°C.	Meta-Analysis	Rate of cooling via cold water immersion (CWI).	Average cooling rate of CWI was 0.08°C·min−1. Cooling was more effective if water temperature was ≤10°C.	No studies included were blinded. Strict exclusion criteria may have eliminated valuable studies.
			Rate of cooling via passive recovery.	Average cooling rate of passive recovery was 0.04°C·min−1. Cooling was more effective if ambient temperature was ≥20°C.
F.G. Gaudio et al 2016 USA	Human subjects diagnosed with either exertional or non-exertional heat stroke.	Systematic Review	Efficacy of cooling methods.	Whole-body iced water immersion is the most effective method. Combining cool water spraying and fanning is also effective. Effective methods can be augmented with cold IV fluids or ice packs. Insufficient evidence exists to support the use of cooling blankets or strategically placed ice packs at primary cooling methods.	No mention of quality assessment of papers. Results not presented in a way conducive for modality comparison. Small study sizes limit the reliability of some conclusions drawn.
B.P. McDermott et al 2009 USA	Patients with exercise-induced hyperthermia with pre-treatment temperatures above 38.5°C	Systematic Review	Rate of cooling.	Ice and cold water immersion cooled patients the fastest, with rates of 0.044°C-0.35°C min-1, with the coldest water temperature of 2°C being the most efficient. (n=122 total). Fine spraying cooled at a rate of 0.175°C min−1. (n=2). Dousing with water whilst fanning cooled at a rate of 0.15°C · min−1. (n=52). Ice-wet towels cooled at a rate of 0.11°C · min−1. (n-7). IV fluids with ice packs at major arteries (n=1) or ice wet towels (n=1) cooled at rates of 0.107°C · min−1 and 0.097°C · min−1, respectively.	No studies included blinding. Three studies did not randomly allocate volunteers. Many of the studies included had very small sample sizes and some of these measured unique methods. Results don’t take body size into account.
A. Bouchama et al 2007 Saudi Arabia	Adult and paediatric patients diagnosed with exertional or classic heatstroke.	Adult and paediatric patients diagnosed with exertional or classic heatstroke.	Cooling method efficiency in classic heatstroke.	Conductive methods appear more effective than evaporative methods. Iced water immersion appears more efficient than ice pack placement.	Mostly case-series, with two randomised controlled trials.
			Cooling method efficiency in exertional heatstroke.	Conduction cooling via iced water immersion appears most efficient. Other conduction and evaporation techniques appear to gain similar results.
J.K. DeMartini et al 2011 USA	16 healthy subjects aged 19-39 subjected to exercise-induced hyperthermia.	Comparative Study	Difference in rectal temperature from baseline (38.73 ± 0.12°C) after 10 minutes of cooling therapy.	Cold water immersion, limb immersion and the Emergency Cold Containment System® performed the best, reaching -0.65 ± 0.29°C, -0.74 ± 0.34°C and -0.68 ± 0.24°C from baseline respectively.	Hyperthermia in subjects in limited by what is possible in a controlled trial. Cooling data only accounts for the first 10-30 minutes of therapy. Small sample size.
W. Sinclair et al 2009 Australia	11 fit and healthy male patients subjected to exercise-induced hyperthermia.	Comparative Study	Therapy efficiency at reducing core body temperature.	Fanning alongside water spraying was more effective at reducing core body temperature in the first 20 minutes of therapy, though by 35 minutes, strategic ice placement and chilled IV fluids performed similarly.	Small sample size.

Comment(s)

The evidence supports iced/cold water immersion as the most effective method of temperature reduction. In an emergency department, this may not be practical for all patients, as not all equipment is compatible with a wet environment. This would have further ramifications if a patient suffered a cardiac arrest. For scenarios where it is appropriate, iced water immersion is the optimum route to reducing core body temperature. In remaining cases, alternative effective methods, such as fanning with water dousing will be required.

Clinical Bottom Line

Iced water immersion is the most effective therapy at reducing core body temperature in hyperthermic patients. Pragmatically, this may not feasible in all patients, where other methods should be considered.

References

1. Zhang, Y., Davis, J., Casa, D., Bishop, P. Optimizing Cold Water Immersion for Exercise-Induced Hyperthermia Medicine & Science in Sports & Exercise 2015; 47(11), pp.2464-2472
2. Gaudio, F. and Grissom, C. Cooling Methods in Heat Stroke The Journal of Emergency Medicine, 2016; 50(4), pp.607-616.
3. McDermott, B., Casa, D., Ganio, M., Lopez, R., Yeargin, S., Armstrong, L. and Maresh, C Acute Whole-Body Cooling for Exercise-Induced Hyperthermia: A Systematic Review Journal of Athletic Training 2009; 44(1), pp.84-93
4. Bouchama, A., Dehbi, M. and Chaves-Carballo, E. Cooling and hemodynamic management in heatstroke: practical recommendations Critical Care 2013; 11(3), p.R54
5. DeMartini, J., Ranalli, G., Casa, D., Lopez, R., Ganio, M., Stearns, R., McDermott, B., Armstrong, L. and Maresh, C. Comparison of Body Cooling Methods on Physiological and Perceptual Measures of Mildly Hyperthermic Athletes Journal of Strength and Conditioning Research 2011; 25(8), pp.2065-2074
6. Sinclair, W., Rudzki, S., Leicht, A., Fogarty, A., Winter, S. and Patterson, M. Efficacy of Field Treatments to Reduce Body Core Temperature in Hyperthermic Subjects. Medicine & Science in Sports & Exercise 2009; 41(11), pp.1984-1990