title: Cooling Effectiveness of a Modified Cold-Water Immersion Method After Exercise-Induced Hyperthermia.
abstract: BACKGROUND
  Recommended treatment for exertional heat stroke includes whole-body cold-water immersion (CWI). However, remote locations or monetary or spatial restrictions can challenge the feasibility of CWI. Thus, the development of a modified, portable CWI method would allow for optimal treatment of exertional heat stroke in the presence of these challenges.
  
  
  OBJECTIVE
  To determine the cooling rate of modified CWI (tarp-assisted cooling with oscillation [TACO]) after exertional hyperthermia.
  
  
  METHODS
  Randomized, crossover controlled trial.
  
  
  METHODS
  Environmental chamber (temperature = 33.4°C ± 0.8°C, relative humidity = 55.7% ± 1.9%).
  
  
  METHODS
  Sixteen volunteers (9 men, 7 women; age = 26 ± 4.7 years, height = 1.76 ± 0.09 m, mass = 72.5 ± 9.0 kg, body fat = 20.7% ± 7.1%) with no history of compromised thermoregulation.
  
  
  METHODS
  Participants completed volitional exercise (cycling or treadmill) until they demonstrated a rectal temperature (Tre) ≥39.0°C. After exercise, participants transitioned to a semirecumbent position on a tarp until either Trereached 38.1°C or 15 minutes had elapsed during the control (no immersion [CON]) or TACO (immersion in 151 L of 2.1°C ± 0.8°C water) treatment.
  
  
  METHODS
  The Tre, heart rate, and blood pressure (reported as mean arterial pressure) were assessed precooling and postcooling. Statistical analyses included repeated-measures analysis of variance with appropriate post hoc t tests and Bonferroni correction.
  
  
  RESULTS
  Before cooling, the Trewas not different between conditions (CON: 39.27°C ± 0.26°C, TACO: 39.30°C ± 0.39°C; P = .62; effect size = -0.09; 95% confidence interval [CI] = -0.2, 0.1). At postcooling, the Trewas decreased in the TACO (38.10°C ± 0.16°C) compared with the CON condition (38.74°C ± 0.38°C; P < .001; effect size = 2.27; 95% CI = 0.4, 0.9). The rate of cooling was greater during the TACO (0.14 ± 0.06°C/min) than the CON treatment (0.04°C/min ± 0.02°C/min; t15= -8.84; P < .001; effect size = 2.21; 95% CI = -0.13, -0.08). These differences occurred despite an insignificant increase in fluid consumption during exercise preceding CON (0.26 ± 0.29 L) versus TACO (0.19 ± 0.26 L; t12= 1.73; P = .11; effect size = 0.48; 95% CI = -0.02, 0.14) treatment. Decreases in heart rate did not differ between the TACO and CON conditions (t15= -1.81; P = .09; effect size = 0.45; 95% CI = -22, 2). Mean arterial pressure was greater at postcooling with TACO (84.2 ± 6.6 mm Hg) than with CON (67.0 ± 9.0 mm Hg; P < .001; effect size = 2.25; 95% CI = 13, 21).
  
  
  CONCLUSIONS
  The TACO treatment provided faster cooling than did the CON treatment. When location, monetary, or spatial restrictions are present, TACO represents an effective alternative to traditional CWI in the emergency treatment of patients with exertional hyperthermia.
authors.affiliation: University of Arkansas, Fayetteville.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Luhring
authors.affiliation: University of Arkansas, Fayetteville.
authors.forename: Cory L
authors.initials: CL
authors.lastname: Butts
authors.affiliation: University of Arkansas, Fayetteville.
authors.forename: Cody R
authors.initials: CR
authors.lastname: Smith
authors.affiliation: University of Arkansas, Fayetteville.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Bonacci
authors.affiliation: Advanced Orthopaedic Specialists, Fayetteville, AR.
authors.forename: Ramon C
authors.initials: RC
authors.lastname: Ylanan
authors.affiliation: University of Arkansas, Fayetteville.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Ganio
authors.affiliation: University of Arkansas, Fayetteville.
authors.forename: Brendon P
authors.initials: BP
authors.lastname: McDermott
mesh_terms: D000328:Adult; D001794:Blood Pressure; D001833:Body Temperature Regulation / Q000502:physiology*; D003080:Cold Temperature; D018592:Cross-Over Studies; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005334:Fever / Q000628:therapy*; D006339:Heart Rate / Q000502:physiology; D018883:Heat Stroke / Q000517:prevention & control; D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods*; D007101:Immersion; D008297:Male; D014867:Water
chemical_list: D014867:Water
keywords: exertional heat stroke; heat illness; heat strain; tarp-assisted cooling