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heat stroke

A life-threatening disorder treated as a medical emergency. Definition (operational) [2] 1) core temperature of > 40.6 degrees C (> 105 degrees F) 2) altered central nervous system function - delirium, stupor, coma, seizures 3) classic (exposure to hot weather) vs exertional Etiology: (risk factors) 1) environmental factors a) ambient temperature > 90 degrees F b) poorly ventilated dwelling c) lack of air conditioning d) high humidity 2) age: infants, children & the elderly 3) predisposing illnesses a) cardiovascular: 1] arteriosclerosis 2] myocardial dysfunction 3] valvular heart disease 4] peripheral vascular disease b) diabetes mellitus c) alcoholism d) dementia e) ectodermal dysplasia f) anhydrosis g) scleroderma (severe) 4) predisposing medications & drugs a) diuretics b) anticholinergic agents c) phenothiazines d) antihistamines e) anti Parkinsonian agents f) antidepressants, especially tricyclic antidepressants g) laxative abuse h) amphetamines i) cocaine j) barbiturates h) hallucinogens Clinical manifestations: 1) manifestations common to all forms of heat injury a) headache b) weakness c) nausea & vomiting d) vertigo e) faintness f) tachycardia g) tachypnea h) hypotension i) skin may be flushed (vasodilation) or pale due to vascular collapse (pallor) 2) other manifestations a) tremor b) dyspnea c) paresthesias d) confusion e) irrational behavior f) core temperature > 106 F g) hot, dry skin h) lethargy, stupor or coma i) flaccid muscle tone j) diminished deep tendon reflexes 3) skin is usually dry in classic form 4) profuse sweating & wet skin with exertional from Laboratory: 1) complete blood count (CBC) may be normal 2) serum chemistries may be normal 3) disseminated intravascular coagulation panel a) D-dimer b) fibrinogen 4) plasma lactic acid 5) arterial blood gas a) respiratory alkalosis b) metabolic acidosis 6) urinalysis Special laboratory: electrocardiography: 1) tachycardia 2) sinus arrhythmia 3) ST segment depression 4) flattened or inverted T waves 5) evidence of myocardial ischemia or acute infarction Differential diagnosis: 1) exertional heat injury 2) heat exhaustion 3) sepsis 4) myocardial infarction 5) neuroleptic malignant syndrome Management: 1) cool patient to 101-102 degrees F; 38.0 C (100.4 F) [5] a) place patient in a cool environment b) maintain adequate ventilation c) cooling fan with spray humidifier (evaporative cooling) d) ice-water immersion (exertional heat stroke only) [2] - a cooling rate of 1 degree C in 3-10 minutes safe [4] - ice water immersion of elderly with non-exertional hyperthermia associated with excess mortality e) monitor core temperature f) discontinue aggressive attempts to lower temperature when core temperature reaches 101-102 degrees F g) clinical improvement tends to be rapid & sustained with reduction in temperature [2] - return to baseline most likely prognosis [5,6] 2) massage skin to stimulate return of cooled blood to core organs & brain 3) hydrate with 1/2 normal saline 4) monitor for signs of congestive heart failure & pulmonary edema 5) follow-up within 1 week a) ensure complete recovery b) work-up & management of pre-existing illness as indicated 6) patient education a) precipitating factors b) rescources available

Related

hyperthermia (pyrexia)

Specific

heat syncope

General

heat injury; heat stress; heat illness

References

  1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 1178-80
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, 17, 18. American College of Physicians, Philadelphia 1998, 2015, 2018.
  3. O'Connor JP. Simple and effective method to lower body core temperatures of hyperthermic patients. Am J Emerg Med. 2017 Jun;35(6):881-884. PMID: 28162872
  4. NEJM Resident 360. June 19, 2019 https://resident360.nejm.org/clinical-pearls/heatstroke
  5. Epstein Y, Yanovich R. Heatstroke. N Engl J Med. 2019;380(325):2449-2459 PMID: 31216400 https://www.nejm.org/doi/10.1056/NEJMra1810762
  6. Ito C, Takahashi I, Kasuya M et al Safety and efficacy of cold-water immersion in the treatment of older patients with heat stroke: a case series. Acute Med Surg. 2021 Feb 19;8(1):e635. PMID: 33659066 PMCID: PMC7893982 Free PMC article.
  7. Hyperthermia-Too Hot for Your Health http://www.niapublications.org/engagepages/hyperther.asp