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Predicting poor outcomes in heatstroke

Three Part Question

In [adult patients presenting to the ED with heatstroke] what are the [risk factors] for [poor outcome]?

Clinical Scenario

A 50 year old male is brought in by ambulance after a collapse. It is a hot day and the patient had been playing 5-aside football when he collapsed. In the Emergency Department he is a assessed, having a rectal temperature of 41.5C and a GCS of 4. The patient is hot and not sweating. A diagnosis of heatstroke is made. You wonder which factors of this patient’s situation in the ED might be prognostically predictive.

Search Strategy

Ovid Medline® 1950 to June Week 2 2009
Ovid Embase 1980 to 2009 Week 25
Ovid EBM Reviews- Cochrane Central Register of Controlled Trials 2nd Quarter 2009
Ovid EBM Reviews - Cochrane Database of Systematic Reviews 2nd Quarter 2009

Medline®, Embase & Cochrane search strategies;
1 exp Heat Stress Disorders/
2 exp Hospital Mortality/ or exp Intensive Care/ or exp Intensive Care Units/ or or exp Critical Care/ or exp Respiration, Artificial/
3 exp Multiple Organ Failure/ or multi organ
4 3 or 2
5 4 and 1
6 limit 5 to (human and english language)

CINAHL Plus search strategy;
1. (MH "Heat Stroke") or (MH "Heat Exhaustion") AND (("hospital mortality") or (MH "Hospital Mortality") or (multi organ dysfunction)

Search Outcome

The search produced 662 results (Medline 48, Embase 610, Cinahl 4), of which 18 were good quality, relevant results. This BET limits ‘adult patients’ to those >18 and <65 years of age. As such, some results were omitted owing to their focus on increased mortality amongst the elderly and the elderly with concomitant illness. 6 papers were considered to be of sufficient specifity to be included in this review, of which 5 are retrospective studies and the 6th is a meta-analysis of cohort & case control studies.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Barbieri A. Pinna C. Fruggeri L. Biagioni E. Campagna A.
9 patients admitted to ICU at Modena Teaching Hospital in Summer 2003 with hyperthermia syndrome. A 10th patient died soon after admission, initial data only. Male N=5 Female N=5 Retrospective Observational StudyBody Temperature on admission & at 24 hours41.3°C± 1.3°C mean body temperature. Direct association between body temperature on admission & 24 hours & mortalitySmall number of patients investigated. Mean age of sample group 56.4 ± 24.5 years- wide range therefore difficult to contrast outcomes.
Mortality80% with mean survival time 4.2 days, median value of 1 day
Common Features of ICU Admissions80% of patients investigated were taking psychoactive drugs. Statistically significant (P <0.001)
Davido A. Patzak A. Dart T. Sadier MP. Meraud P. Masmoudi R. Sembach N. Cao TH.
165 patients admitted to ED of Hopital Europe en Georges Pompidou during 7 day heat wave period, 2003. Mainly elderly women.Retrospective analysis.Short-term mortality18.8% died within 1 monthRetrospective study- charts assessed missing some data.
Factors associated with short-term mortalityClinically more severe on admission, higher blood glucose, troponin & white blood cells. Lower serum protein and PT levels, pre-existing ischaemic cardiomyopathy, pneumonia, previous psychotropic treatments.
Bouchama A., Dehbi M., Mohamed G., Matthies F., Shoukri M., Menne B.
Saudi Arabia
Patients included within 6 case-control studies of 1065 heat-wave related deaths.Meta-analysis of observational studies (case-control/cohort)Factors associated with highest mortalityConfinement to bed, not being mobile and leaving the house, psychiatric illness (>cardiovascular>pulmonary).
Factors associated with better outcomesIncreased social contact, visiting cool environments, home air-conditioning, taking extra showers/baths and using fans.
LoVecchio F., Pizon A.F., Berrett C., Balls A.
52 patients from August 2003-2005.Retrospective Analysis. 2 Emergency Departments. Mean body temperature40.6°C (37.9°C- 44.0°C). Mortality worsened with higher presentation temperature.Retrospective data. By admission of the authors the patient evaluation and test ordering lacked homogeneity.
Glasgow coma scale<14 in 69.2%
Creatinine level/Creatinine Kinase>1.5mg/dL in 40.4% with CK >200U/L in 67.3%
Prothrombin time>13 seconds in 57.7%
Aspartate Aminotransferase>45U/L in 55.8%
Glucose<60mg/dL in only 5.7%
Ethanol/illicit drugsInvolved in 34.6%
Mean hospital stay4.7 days (range 1-30 days)
Hospital mortality28.8%
Misset B., De Jonghe B., Bastuji-Garin S., Gattolliat O., Boughrara E., Annane D., Hausfater P., Gar
345 patient’s data from ICU admission for heatstroke in France’s 2003 heat wave.Retrospective analysis. Data identified through questionnaires sent to intensivists across France. Hospital mortality62.6% mortality with 56.5% of these dying in the ICU. The median survival time was 13.1 days (range 1.6-62.0 days).
Occurrence of heatstroke50.6% at home, 49.4% in a healthcare facility or in a public place. Those occurrences at home were associated with a worse outcome.
Simplified Acute Physiology Score II (SAPS-II)SAPS-II in nonsurvivors 79.6±19.6 compared with a lower SAPS-II seen in survivors, 54.1±16.3.
Creatinine Kinase1258IU/mL (299–4442 IU/mL) in nonsurvivors vs. 836 (268–3185 IU/mL) in survivors. Higher CK value associated with worse outcome.
Prothrombin time22 secs (17–34 secs) in nonsurvivors vs. 16 secs (14–19 secs) in survivors. Higher PT time associated with worse outcome.
Air conditioned ICUSurvivors more likely to have been managed in an air-conditioned ICU (55%).
Varghese G.M., John G., Thomas K., Abraham O.C., Mathai D.
28 adult patients admitted to Southern Indian hospital January 1998- December 2001.Retrospective analysis75% of the 28 patients developed multiple organ dysfunction (MODS), most commonly involved was respiratory failure.Predictors correlating strongly with MODS (of two or more organs) in heatstroke identified as; Metabolic acidosis in 87.5% (p=0.011) Elevated creatinine phosphokinase 89.5% (p=0.005) Liver enzymes >x2 of normal in 61% (p=0.02)Relatively small sample size, restricted to one hospital site therefore difficult to generalise.


As the 21st century progresses the incidence and severity of heat waves are set to increase. Those considered to be something of an extreme phenomena (France, 2003) are predicted to become an annual feature of the British Summer by 2080. As such, Emergency Departments must be prepared to deal with the victims of heatstroke and triage those affected by the range of heat-related illnesses. National prevention programs are essential, with the implementation of the Department of Health’s ‘Heat wave Plan’ requiring all Emergency Departments to be prepared and equipped for heat wave scenarios. Despite medical advances the mortality associated with heatstroke is still extremely high. It is clear that the elderly and unwell are at particular risk of heat-related illnesses. Both psychiatric illness and medications are notably associated with an increased mortality. However, it is also apparent that early predictors of mortality exist and ought to be investigated, further data generated and real clinical results reported upon. The most notable predictors of mortality identified in this review would seem to creatinine kinase, liver enzymes, prothrombin time, initial body temperature, GCS, age, underlying illnesses and the taking of psychoactive medications.

Clinical Bottom Line

The risk factors for a poor outcome in heatstroke go beyond those recorded at initial assessment. Rectal temperature and neurological deterioration remain key is diagnosis and an in the gauging of severity of presentation. Beyond this, factors in the patient’s medical, social and presenting history, as well as laboratory results, can be predictive in case by case prognosis.


  1. Barbieri A. Pinna C. Fruggeri L. Biagioni E. Campagna A. Heat wave in Italy and hyperthermia syndrome. Southern Medical Journal. 99(8):829-31, 2006 Aug.
  2. Davido A. Patzak A. Dart T. Sadier MP. Meraud P. Masmoudi R. Sembach N. Cao TH. Risk factors for heat related death during the August 2003 heat wave in Paris, France, in patients evaluated at the emergency department of the Hopital Europeen Georges Pompidou. Emergency Medicine Journal. 23(7):515-8, 2006 Jul.
  3. Bouchama A., Dehbi M., Mohamed G., Matthies F., Shoukri M., Menne B. Prognostic factors in heat wave-related deaths: A meta-analysis. Archives of Internal Medicine. 167(20)(pp 2170-2176), 2007. Date of Publication: 12 Nov 2007.
  4. LoVecchio F., Pizon A.F., Berrett C., Balls A. Outcomes after environmental hyperthermia. American Journal of Emergency Medicine. 25(4)(pp 442-444), 2007. Date of Publication: May 2007.
  5. Misset B., De Jonghe B., Bastuji-Garin S., Gattolliat O., Boughrara E., Annane D., Hausfater P., Garrouste-Orgeas M., Carlet J. Mortality of patients with heatstroke admitted to intensive care units during the 2003 heat wave in France: A national multiple-center risk-factor study. Critical Care Medicine. 34(4)(pp 1087-1092), 2006. Date of Publication: Apr 2006.
  6. Varghese G.M., John G., Thomas K., Abraham O.C., Mathai D. Predictors of multi-organ dysfunction in heatstroke. Emergency Medicine Journal 22(3)(pp 185-187), 2005. Date of Publication: Mar 2005.