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WORKSHEET for Evidence‐Based Review of Science for First Aid Worksheet author(s) Susan W. Yeargin, PhD, ATC Date Submitted for review: Initial: 11/30/09 Clinical question. General: What is the best treatment for a victim of heat exhaustion or heat syncope? PICO Format: In victims with heat exhaustion or heat syncope (P) what treatment (I) as opposed to no treatment (C) decreases/resolves symptoms (O)? Is this question addressing an intervention/therapy, prognosis or diagnosis? Intervention State if this is a proposed new topic or revision of existing worksheet: New Topic Conflict of interest specific to this question Do any of the authors listed above have conflict of interest disclosures relevant to this worksheet? Yes, Intellectual interest Search strategy (including electronic databases searched). Cochrane Reviews, DARE, and CENTRAL: “heat exhaustion” OR “heat syncope” OR “heat fainting” AND “treatment” OR “first aid” OR “management” Medline, PubMed, PubMed Central, CINAHL, and Pre CINAHL: same search terms as above MESH Terms: Blood Circulation* Drinking* Exercise* Body Water/*metabolism Dehydration/*physiopathology Stress, Physiological/physiopathology Energy Metabolism* Hemodynamics* Heat Exhaustion/*physiopathology Heat Exhaustion/enzymology Water‐Electrolyte Imbalance/blood Heat Exhaustion/*etiology Occupational Exposure/*adverse effects • State inclusion and exclusion criteria Inclusionary items: heat exhaustion, heat syncope, heat fainting, and heat illness Exclusionary items: special populations (i.e cystic fibrosis, multiple sclerosis, musculoskeletal diseases, seizures), animals, pharmacological treatment, cooling for performance studies, fainting in non heat situations, non peer reviewed studies, missing abstract manuscripts, and studies not directly answering the question • Number of articles/sources meeting criteria for further review: 26 articles currently meet criteria for review. Of these 8 were LOE 2, 10 were LOE3, 8 were LOE5. Worksheet No. FA-1706A
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Summary of evidence Evidence Supporting Clinical Question Good Fair Poor Costrini 1979 A Kark 1996 A Donaghue 2000 AD Donaghue 2000 AD Armstrong, 1988 C Nash 1985, A Brown 1947 A Castellani, 1997 D Kenefick, 2000 D Kenefick 2006 D Kenefick 2007 D Maresh 2001 D Riebe 1997 D Donaghue 2000 A Armstrong 1997 D Richards 1979, DE Mitchell, 2001 E Kielblock 1996 E Shahid 1999 C Holtzhausen 1994 A Armstrong, 1998 A Nadel 1941 A 1 2 4 5 A = EHE/EHSnc‐ water depletion B= EHE/EHSnc‐ salt depletion C= EHE/EHSnc‐ circulatory insufficiency D= Relief of symptoms/etiology via oral rehydration E= Relief of symptoms/etiology via cooling 3 Level of evidence ICD, 2009 ABC Hadad 2004 E Hubbard 1988 AB Adolf 1947 A Worksheet No. FA-1706A
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Evidence Neutral to Clinical question Good Fair Poor 1 2 4 5 3 Level of evidence Evidence Opposing Clinical Question Good Fair Poor 1 2 4 5 3 Level of evidence Worksheet No. FA-1706A
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REVIEWER’S FINAL COMMENTS AND ASSESSMENT OF BENEFIT / RISK (please include implementation considerations including at a minimum training, environment and availability: There is no controlled research on the treatment of heat exhaustion and heat syncope. The only studies that involve management of the heat illnesses are observational studies or case studies at running events or occupational individuals (miners, military). The rest of the studies are prospective or retrospective studies examining the etiology of the heat illnesses. Even though the studies do not directly look at treatment, by understanding the etiology and attempting to address these factors, a treatment plan can be developed. Heat exhaustion is defined as the inability to continue exercise in the heat because of cardiovascular insufficiency. Observation studies and case reports have indicated water depletion as a factor contributing to heat exhaustion(Costrini 1979, Kark 1996, Donoghue 2000, Donoghue 2000, Donoghue 2000). Observational studies have also shown salt depletion as a contributing factor to heat exhaustion(Costrini 1979, Kark 1996, Donoghue 2000, Donoghue 2000, Donoghue 2000). Some of these studies also observed rehydration through either oral or IV fluids and documented a resolution in symptoms. It can be assumed because the water and sodium depletion was addressed in the fluids administered. No studies have been done to see if individuals would have recovered without fluids. However it is known from a controlled study, that physiological strain is higher in individuals who are not provided fluids during exercise. It might be assumed the same is relevant during recovery. Randomized controlled studies have examined oral versus IV and have shown that oral is just as beneficial as IV to provide fluids to help rehydrate individuals(Castellini 1997, Kenefick2000, Kenefick 2007, Riebe1997, Marehs 2001, Armstrong 1997). Observational studies (and expert opinion) have shown that circulatory insufficiency is present in almost all forms of heat exhaustion and heat syncope (most likely because of the water and/or salt depletion)(Costrini 1979, Kark 1996, Shahid1999, Holtzhausen 1994, Armstrong 1997). The replacement of water and salt will most likely address this factor by increasing plasma volume and cardiac output. As well, any form of cooling may encourage peripheral vasoconstriction resulting in an increase in central volume and cardiac output. Numerous controlled studies support various methods of cooling that are successful in aiding in evaporation and therefore peripheral vasoconstriction(Donoghue 2000, Hadad 2004, Richards 1979, Mitchell 2001, Kielblock 1986). When core body temperature decrease is not the primary objective, many methods could be used such as fans, dousing/spraying, and ice packs. One observation study also documented the environmental conditions when EHE (Exertional Heat Exhaustion occurred to report how warm/hot environments increase the incidence of EHE, most likely contributing to the water/salt depletion and circulatory insufficiency (Donoghue 2000). Therefore, cooling may help in this factor as well. Having the individual lie down and elevate the feet, may also encourage blood return and help with cardiac output to address circulatory insufficiencies. Heat syncope is defined as a fainting episode in the heat caused by cardiovascular insufficiency (blood pooling in the extremities). Since the etiology is very similar to heat exhaustion, the same treatment plan can be used. However, it is important to note, that a well hydrated person can have heat syncope due to a quick cessation of exercise or standing for long periods of time causing the blood pooling. . Acknowledgements:
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(1999). International Classification of Diseases. N. C. f. H. Statistics. 10.
Government and world health organization recognition of signs and symptoms of EHE and
EHSnc and the etiology of water and sodium depletion.
Adolf, E. F. (1947). Life in deserts. New York, Intersceince.
An observational study of soldiers marching in the desert. Noted the soldiers did not recover from
heat exhaustion by simply resting or cooling, that rehydration was necessary for resolution of
symptoms.
Armstrong, L. E., R. W. Hubbard, et al. (1988). "Signs and symptoms of heat exhaustion during
strenuous exercise." Annals of Sports Medicine 3: 182-189.
An observation study of subjects running on a treadmill. Documented the s/s associated with
exhaustion. Of which, s/s of circulatory insufficiency were common (increased heart rate,
dizziness). Supports addressing circulatory issues.
Armstrong, L. E., R. W. Hubbard, et al. (1988). "Heat intolerance, heat exhaustion monitored: a case
report." Aviation, Space, And Environmental Medicine 59(3): 262-266.
A well supported case study. Reveals significant water and salt depletion in the heat
exhaustion victim. Supporting the need to treat these factors.
Armstrong, L. E., C. M. Maresh, et al. (1997). "Thermal and circulatory responses during exercise:
effects of hypohydration, dehydration, and water intake." Journal Of Applied Physiology (Bethesda,
Md.: 1985) 82(6): 2028-2035.
Well designed controlled study. Supports the use of oral rehydration to decrease physiological
strain. Even though focused on post exercise, still provides insight into the recovery period.
Brown, A. H. (1947). Physiology of man in the desert. New York, Interscience.
An observational study of soldiers marching in the desert. Made the correlation between heat
exhaustion and dehydration (3-11% body water losses). Supports the use of oral rehydration
with fluids.
Castellani, J. W., C. M. Maresh, et al. (1997). "Intravenous vs. oral rehydration: effects on
subsequent exercise-heat stress." Journal Of Applied Physiology (Bethesda, Md : 1985) 82(3): 799806.
Solid research design. Results suggest when treating with a NaCl solution, that there is no
benefit of choosing intravenous fluids over oral rehydration.
Costrini, A. M., H. A. Pitt, et al. (1979). "Cardiovascular and metabolic manifestations of heat stroke
and severe heat exhaustion." The American Journal Of Medicine 66(2): 296-302.
An observational study in the military. Revealed EHE patients are dehydrated, sodium
depleted, and has circulatory insufficiencies.
Donoghue, A. M. and G. P. Bates (2000). "The risk of heat exhaustion at a deep underground
metalliferous mine in relation to body-mass index and predicted VO2max." Occupational Medicine
(Oxford, England) 50(4): 259-263.
A prospective study of occupational subjects (miners). Revealed that subjects were
dehydrated at time of heat exhaustion and that the use of IV fluids to rehydrate resolved
symptoms.
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Donoghue, A. M. and G. P. Bates (2000). "The risk of heat exhaustion at a deep underground
metalliferous mine in relation to surface temperatures." Occupational Medicine (Oxford, England)
50(5): 334-336.
A prospective study using occupational subjects (miners). Revealed environmental
temperature is correlated with heat exhaustion.
Donoghue, A. M., M. J. Sinclair, et al. (2000). "Heat exhaustion in a deep underground metalliferous
mine." Occupational And Environmental Medicine 57(3): 165-174.
A prospective study of occupational subjects (miners). Revealed that subjects were
dehydrated at time of heat exhaustion and that the use of IV fluids to rehydrate resolved
symptoms. Also revealed that warm/hot environmental conditions are correlated with heat
exhaustion.
Hadad, E., M. Rav-Acha, et al. (2004). "Heat stroke : a review of cooling methods." Sports Medicine
(Auckland, N Z ) 34(8): 501-11.
A review of cooling methods (specifically to heat stroke). Discusses that that evaporative
cooling methods such as fans and spraying result in vasoconstriction, which is helpful to
increase central volume and cardiac output. These methods are useful when core body
temperature is not a concern.
Holtzhausen, L. M., T. D. Noakes, et al. (1994). "Clinical and biochemical characteristics of collapsed
ultra-marathon runners." Medicine And Science In Sports And Exercise 26(9): 1095-1101.
An observational study of runners. Revealed EHE victims are dehydrated, sodium depleted,
and have circulatory insufficiencies.
Hubbard, R. W. and L. E. Armstrong (1988). Human Performance physiology and environmental
medicine at terrestrial extremes. Indianapolis, Benchmark Press.
Kark, J. A., P. Q. Burr, et al. (1996). "Exertional heat illness in Marine Corps recruit training."
Aviation, Space, And Environmental Medicine 67(4): 354-360.
An observation study of military personnel. Revealed that heat exhaustion patients were
dehydrated, sodium depleted, and have circulatory insufficiencies.
Kenefick, R. W., C. M. Maresh, et al. (2000). "Plasma vasopressin and aldosterone responses to oral
and intravenous saline rehydration." Journal Of Applied Physiology (Bethesda, Md.: 1985) 89(6):
2117-2122.
Solid research design. Results support that when treating with a NaCl solution there is no
difference between intravenous or oral rehydration methods.
Kenefick, R. W., C. M. Maresh, et al. (2007). "Rehydration with fluid of varying tonicities: effects on
fluid regulatory hormones and exercise performance in the heat." Journal Of Applied Physiology
(Bethesda, Md : 1985) 102(5): 1899-905.
Solid research design. Results support that when treating with a NaCl solution, there is no
difference between intravenous and oral rehydration methods.
Kenefick, R. W., K. M. O'Moore, et al. (2006). "Rapid IV versus oral rehydration: responses to
subsequent exercise heat stress." Medicine And Science In Sports And Exercise 38(12): 2125-31.
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Solid research design. Results support when using a NaCl solution, there is not a difference
between intravenous and oral rehydration methods.
Maresh, C. M., J. A. Herrera-Soto, et al. (2001). "Perceptual responses in the heat after brief
intravenous versus oral rehydration." Medicine And Science In Sports And Exercise 33(6): 10391045.
Good research design. Results suggest that the oral rehydration is better than IV at
decreasing sensations of thirst.
Kielblock, A. J., J. P. Van Rensburg, et al. (1986). "Body cooling as a method for reducing
hyperthermia. An evaluation of techniques." South African Medical Journal = Suid-Afrikaanse
Tydskrif Vir Geneeskunde 69(6): 378-80.
A well designed study. A combination of ice bags and air had the highest cooling rate and
aided in evaporation.
Mitchell, J. B., E. R. Schiller, et al. (2001). "The influence of different external cooling methods on
thermoregulatory responses before and after intense intermittent exercise in the heat." J Strength
Cond Res 15(2): 247-54.
Fan and mister cooling were no more effective than passive cooling in cool air. Cooling rates
were sufficient and aided in evaporation.
Nadal, J. W., S. Pedersen, et al. (1941). "A COMPARISON BETWEEN DEHYDRATION FROM
SALT LOSS AND FROM WATER DEPRIVATION." The Journal Of Clinical Investigation 20(6): 691703.
A strong discussion on how both dehydration and sodium depletion together and separate
play a role in circulatory insufficiencies (decrease in plasma volume, changes vascular
resistance, decrease in cardiac output, increases in heat rate)
Nash, H. L. (1985). "Treating thermal injury: disagreement heats up." The Physician and
Sportsmedicine 13: 134-144.
An observation study of runners. All heat exhaustion cases were treated with rehydration (via
IV fluids) and 90% were able to leave the finish line medical tent on their own. Supports the
use of oral rehydration with a NaCl solution.
Richards, D., R. Richards, et al. (1979). "Management of heat exhaustion in Sydney's the Sun Cityto-Surf run runners." The Medical Journal Of Australia 2(9): 457-461.
A well controlled treatment study. EHE patients were treated with various cooling methods to
aid in evaporation and fluids for rehydration. All had successful resolution of symptoms.
Riebe, D., C. M. Maresh, et al. (1997). "Effects of oral and intravenous rehydration on ratings of
perceived exertion and thirst." Medicine And Science In Sports And Exercise 29(1): 117-24.
Solid research design. Results suggest that when treating with a NaCl solution, use of oral
rehydration may be of benefit to decrease perceptual sensations in the dehydration victim.
Shahid, M. S., L. Hatle, et al. (1999). "Echocardiographic and Doppler study of patients with
heatstroke and heat exhaustion." International Journal Of Cardiac Imaging 15(4): 279-285.
A retrospective study of pilgrimage heat exhaustion victims. Reveals circulatory insufficiencies
are correlated with heat exhaustion.