Heat Exhaustion/Stroke

ER series 3 — Heat stroke

In the previous week we’ve been experiencing crazy good weather in Vancouver—so good that when I took a friend bike riding around Stanley Park, I got sunburnt on my face and arms! Crazy! Heat stroke seems like such a wimpy thing to get, but coming from Australia where it gets up to 40 degrees Celsius, heat stroke can be fatal; so we take heat stroke and sunscreen very seriously.

Most of time, people complaining about “getting heat stroke” are not actually getting heat stroke. Heat exhaustion is a step below heat stroke and affects young adults who overexert themselves, older adults who cannot dissipate heat at rest (for example, people who are on anticholinergic drugs such as antihistamines or tricyclic antidepressants), or people who are on neuroleptic drugs (for example, schizophrenics). Heat stroke refers to a life-threatening condition where the normal compensatory heat-shedding mechanisms fail.

Basically all the symptoms of heat exhaustion/stroke arise from depletion of water and salt from the circulating heat.

	Exhaustion	Classic	Exertional
Clinical features	· Malaise, headache, fatigue · Body temp <40.5°C · Only signs of dehydration (increase HR, orthostatic hypotension)	· Occurs in high ambient temperatures · Patients often older, poor, sedentary · Dry, hot skin · Body temp >40.5°C · Altered mental status, seizures, delirium, coma · May have elevated AST and ALT	· Occurs with high endogenous heat production and overwhelmed homeostatic mechanisms · Patient often young and active · Skin often diaphoretic · Like classical heat stroke but may have DIC, ARF, rhabdomyolysis, marked lactic acidosis
Management	· Rest in cool environment · Replace water loss PO slowly; normal saline IV for orthostatic hypotension	· Cool with water mist and standing fans · Secure airway in case of seizure and aspiration · Fluid resuscitation · Ice water immersion only if closely monitored

Avoid epinephrine (which causes peripheral vasoconstriction) and antipyretics.

If patient doesn’t respond to therapy, look for other conditions that cause hyperpyrexia but NOT considered heat stroke:

·      Meningitis

·      Thyroid storm

·      Anticholinergic poisoning

·      Delirium tremens

·      Infection

If you would like to contribute to this topic or suggest other topics, please email me at musicdoctor.oli@gmail.com. This blog entry is also available in podcast form! Look for us on iTunes or at www.medonthego.podbean.com.