Question Of The Day #49

This patient presents to the Emergency Department with altered mental status.  This presenting symptom can be due to a large variety of etiologies, including hypoglycemia, sepsis, toxic ingestions, electrolyte abnormalities, stroke, and more.  The management and evaluation of a patient with altered mental status depends on the primary assessment of the patient (“ABCs”, or Airway, Breathing, Circulation) to identify any acute life-threatening conditions that need to be managed emergently, the history, and the physical examination.  One mnemonic that may help in remembering the many causes of altered mental status is “AEIOUTIPS”.  The table below outlines this mnemonic.

Hyperthermia (or hypothermia) can cause altered mental status.  This patient arrives with altered mental status, severe hyperthermia, tachycardia, tachypnea, and hypotension.  The history of the patient running outside for exercise should raise concern for hyperthermia related to excess heat production due to overexertion.  This should narrow the differential diagnoses to heat exhaustion (Choice B) and heat stroke (Choice C).  Both heat exhaustion and heat stroke are marked by hyperthermia with temperatures often over 40ᵒC. Additional symptoms include weakness, nausea, vomiting, myalgias, syncope, and headache.  The differentiating factor between heat exhaustion and heat stroke is altered mental status and sweating.  Patients with heat exhaustion lack altered mental status and should still be able to thermoregulate through sweating.  On the contrary, heat stroke patients are more severely ill as they have altered mental status and can no longer thermoregulate with sweating.  The treatment in both conditions should be early and aggressive cooling measures.  This includes full body immersion in an ice bath, removal of clothes, and cold IV fluids.  Internal cooling with gastric, bladder, pleural, or peritoneal lavage with cold fluids can be done on more sick patients.  Antipyretic medications, like NSAIDs and paracetamol, have no benefit in patients with severe hyperthermia.  Evaluation for rhabdomyolysis, kidney failure, liver failure, sepsis, or other organ dysfunction should also be a part of the evaluation of hyperthermic patients.

Sympathomimetic toxicity (Choice A) is possible, but less likely as the skin is dry and the history of exercise outdoors.  Sympathomimetic toxicity manifests as diaphoresis, tachycardia, hypertension, hyperthermia, and sometimes altered mental status.  Thyroid storm (Choice D) is another possibility.  This diagnosis can also present with similar vital signs, hyperthermia, and altered mental status.  Again, the history of outdoor exercise should point more towards heat exhaustion vs heat stroke.

The diagnosis of this patient is heat stroke (Choice C) as he has altered mental status and lacks wet skin.

Correct Answer: C