Introduction
Materials and methods
Search strategy
Selection criteria
Cooling methods
Hemodynamic management
Endpoints and definitions
Features | Classic | Exertional |
---|---|---|
Common | ||
Hyperthermia | > 40°C | > 40°C |
Central nervous system alteration | Delirium, convulsion | Delirium, convulsion |
Hypotension | 20%–30% | Unknown |
Distinctive | ||
Age | Elderly | Young |
Skin | Hot, dry | Hot, profuse sweating |
Rhabdomyolysis | Mild/moderate | Severe |
Renal failure | Uncommon | Common |
Lactic acidosis | Mild/moderate | Severe |
Glycemia | Hyperglycemia | Hypoglycemia |
Disseminated intravascular coagulation | Mild/moderate | Severe |
Results
Search results
Study (country, year) | Population | Study design | Intervention | Outcomes measured | Results | Limitations |
---|---|---|---|---|---|---|
[18] (Israel, 1967) | Exertional heatstroke (n = 36) | Case series | Ice-filled rubber bottles over the whole body; cool air-conditioned room; target Trect: not given | Mortality; morbidity | Mortality: 22.2%; neurologic morbidity: 11.1% | Patients enrolled over 10-year period; no cooling time provided; cooling performed in different centers |
[19] (U.S., 1975) | Exertional heatstroke (n = 15) | Case series | Iced water immersion; target Trect: 38.8°C | Mortality; morbidity | Mortality: 0%; neurologic morbidity: 0% | None |
[20] (U.S., 1975) | Exertional heatstroke (n = 13) | Case series | Iced water immersion; target Trect: 38.3°C | Cooling time; mortality; morbidity | Cooling time: < 60 minutes, 92.3%; cooling time: > 60 minutes, 7.7%; mortality: 0%; neurologic morbidity: 0% | None |
[21] (U.S., 1979) | Exertional heatstroke (n = 13) | Case series | Iced water immersion; target Trect: 38.3°C to 38.8°C | Cooling time; mortality; morbidity | Cooling time (range): 10 to 40 minutes; myocardial ischemia: 7.7%; neurologic morbidity: 0%; mortality: 0% | None |
[30] (U.S., 1996) | Exertional heatstroke (n = 21) | Randomized controlled trial | Iced water immersion (1°C to 3°C) torso and upper legs (n = 14) versus wet towel and air exposure at 24.4°C (n = 7); target Trect: 38.2°C to 40.1°C | Cooling rate | Conductive-based cooling faster than evaporative (0.20 ± 0.02 versus 0.11 ± 0.02°C/minute) | Small sample size; comparability of baseline characteristics undetermined; randomization method not specified; evaporative technique suboptimal |
Study (country, year) | Population | Study design | Intervention | Outcomes measured | Results | Limitations |
---|---|---|---|---|---|---|
[16] (U.S., 1982) | Classic heatstroke (n = 28) | Case series | Iced water immersion; brisk massage with ice; target Trect: ≤38.9°C | Cooling time; mortality; morbidity | Cooling time: < 30 minutes, 93%; cooling time: 30 to 45 minutes, 7%; mortality: 14.3%; neurologic morbidity: 14.3% | Patients switched to brisk massage were not identified |
[24] (U.S., 1986) | Classic heatstroke (n = 39) | Case series | Ice packs to axilla and groin; cold wet sheets applied to torso; ice water lavage; cooling blankets; target Trect: ≤38.9°C | Cooling time; mortality | Cooling time: < 60 minutes, 69%; mortality: 15%; cooling time: > 60 minutes, 31%; mortality: 33%; | Retrospective assignment of group; comparability of the groups at baseline questionable |
Study (country, year) | Population | Study design | Intervention | Outcomes measured | Results | Limitations |
---|---|---|---|---|---|---|
[25] (U.S., 1986) | Classic heatstroke (n = 14) | Case series | Ice to the lateral aspect of the trunk and spraying of tepid water (40°C); fan directed to patients; massage to torso and neck; chilled intravenous solution; target Trect: ≤ 39.4°C | Cooling time; mortality; morbidity | Median (range) cooling time: 60 minutes (34 to 89 minutes); mortality: 7.1%; neurologic morbidity: 0% | Combination of several cooling techniques; relative contribution of each difficult to ascertain |
[27] (Saudi Arabia, 1987) | Classic heatstroke (n = 25) | Case series | Wet gauze sheet with water at 20°C; fan with speed airflow of 2.6 m/s; target Trect: ≤ 39°C | Cooling time; mortality; morbidity | Mean (range) cooling time: 40.4 minutes (20 to 145 minutes); mortality: 0%; morbidity: 24% | No follow-up |
[22] (Kuwait, 1980) | Classic heatstroke (n = 18) | Case series | Body cooling unit*; target Trect: < 38°C | Cooling time; mortality; | Cooling time: 26 to 300 minutes; mortality: 11.1% | No follow-up |
[23] (Kuwait, 1981) | Classic heatstroke (n = 174) | Case series | Body cooling unit*; target Trect: < 38°C | Cooling time; mortality; | Mean (range) cooling time: 78 minutes (20 to 180 minutes); mortality: 14.9% | No follow-up |
[26] (Saudi Arabia, 1986) | Classic heatstroke (n = 16) | Randomized controlled trial | Evaporative cooling using body cooling unit* (n = 8) versus conventional method (wet gauze sheet with water at 25°C and fanning air at 20°C) (n = 8); body cooling unit*; target Trect: ≤ 38.5°C | Cooling time; mortality; morbidity | No significant difference in cooling time; no death in either group; neurologic morbidity: 25% versus 12.5% | Small sample size; randomization method not specified; no follow-up |
Study (country, year) | Population | Study design | Intervention | Outcomes measured | Results | Limitations |
---|---|---|---|---|---|---|
[28] (Saudi Arabia, 1990) | Classic heatstroke (n = 20) | Randomized controlled study | Evaporative cooling + dantrolene 2 to 4 mg/kg IV (n = 8) versus evaporative cooling alone (n = 12); target Trect: ≤ 38.9°C | Cooling time; mortality; morbidity | Cooling time in the dantrolene group lower than control (49.7 ± 4.4 versus 69.2 ± 4.8 minutes; p < 0.01); no difference in morbidity and mortality | Small sample size; randomization method not specified; comparability of baseline characteristics questionable |
[29] (Saudi Arabia, 1991) | Classic heatstroke (n = 52) | Randomized controlled study | Evaporative cooling + dantrolene 2 mg/kg IV (n = 26) versus evaporative cooling + placebo (n = 26); target Trect: ≤ 39.4°C | Cooling time; organ dysfunction; length of hospital stay; mortality | No significant difference between study and control groups for any of the endpoints | None |
Study (country, year) | Population | Intervention | Outcomes measured | Results |
---|---|---|---|---|
[34] (U.S., 1972) | Exertional heatstroke (n = 8) | Pulmonary artery catheter; fluid therapy | Hemodynamic profile; response to fluid therapy; mortality | Hyperdynamic profile, n = 7; hypodynamic profile, n = 1; optimal response to fluid: 1,200 ml per 4 hours and cooling; mortality: 0% |
[31] (U.S., 1979) | Classic heatstroke (n = 7) | Pulmonary artery catheter; fluid therapy | Hemodynamic profile; response to fluid therapy; mortality | Hyperdynamic profile, n = 2; hypodynamic profile, n = 5; failure to respond to fluid: 6,000 ml per 24 hours and cooling; no pulmonary edema; mortality: 71% |
[37] (Saudi Arabia, 1989) | Classic heatstroke (n = 13) | Pulmonary artery catheter; fluid therapy | Hemodynamic profile; response to fluid therapy; mortality | Hyperdynamic profile, n = 13; fluid 400 to 1,200 ml per 4 hours, n = 8, no pulmonary edema; fluid 1,200 to 1,800 ml per 4 hours, n = 5, pulmonary edema; mortality: 7.6% |
[38] (Saudi Arabia, 1993) | Classic heatstroke (n = 10) | Pulmonary artery catheter | Hemodynamic profile; mortality | Hyperdynamic profile, n = 8; hypodynamic profile with normal systemic vascular resistance, n = 1; normodynamic profile, n = 1; mortality: 10% |
[39] (Saudi Arabia, 1991) | Classic heatstroke (n = 34) | CVP monitoring; fluid therapy | CVP; response to fluid therapy; mortality | CVP < 3 cm H2O, n = 12 (35.3%); CVP 3 to 10 cm H2O, n = 16 (47%); CVP >10 cm H2O, n = 6 (17.6%); fluid 500 to 2,500 ml titrated to CVP (3 to 8 cm H2O); optimal response, no pulmonary edema; mortality: 0% |
Cooling methods based on conduction
1. Exertional heatstroke
Immersion in iced water
2. Classic heatstroke
Immersion in iced water
Other cooling methods based on conduction
Cooling methods based on evaporation
Exertional heatstroke
Classic heatstroke
Conventional evaporative cooling
Evaporative cooling using body cooling unit
Cooling methods based on medications
Hemodynamic support
Hemodynamic alterations in exertional heatstroke
Hemodynamic alterations in classic heatstroke
Discussion
Cooling methods
Hemodynamic management
Limitations
Future directions
Conclusion
Key messages
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Rapid cooling and management of circulatory failure are crucial to the prevention of irreversible tissue damage and death in heatstroke.
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The literature review failed to identify reliable clinical data on optimum cooling and hemodynamic management of heatstroke.
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Immersion in iced water is effective among young people, military personnel, and athletes with exertional heatstroke.
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No evidence to support the superiority of any one cooling technique in classic heatstroke was found.
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The circulatory alterations in heatstroke were mostly due to a form of distributive shock associated with relative or absolute hypovolemia.