EM@3AM – Hyperthermia

Author: Brit Long, MD (@long_brit, EM Attending Physician, San Antonio, TX) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital)

Welcome to EM@3AM, an emDocs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

A 23-year-old male is brought in by EMS with agitation. He is extremely difficult to control, and you ask for help with physical restraint and then order chemical sedation. His VS include T 41 C, HR 133, BP 182/115, Sats 98% on RA, RR 26, D stick 118.

What’s the diagnosis, and what’s your next step in evaluation and treatment?

Answer: Hyperthermia and Agitation

Hyperthermia is defined by body temperature greater than body’s intrinsic regulatory set point from excessive heat production or inefficient heat dissipation. This is not the same as fever, which involves elevation in body’s internal set point. Patients with agitation and hyperthermia present several challenges for emergency clinicians.



  • Excessive heat production: exertional, malignant hyperthermia, neuroleptic malignant syndrome (NMS), serotonin syndrome (SS), thyrotoxicosis, pheochromocytoma, seizure, intoxication, infection
  • Diminished dissipation: heat stroke, autonomic dysfunction, NMS, SS, anticholinergic poisoning, dehydration, hypothalamic dysfunction (stroke, encephalitis, NMS, granulomatous disease, trauma)

Hyperthermia is associated with elevated body temperature, increased autonomic function, increased metabolic rate. May experience altered mental status, seizure, rhabdomyolysis, DIC, liver failure, renal failure.


Evaluation and Management:

Primary goals are to determine the underlying cause and begin treatment.  These patients are a danger to themselves and require emergent resuscitation.

Evaluate ABCDE’s and vital signs. Obtain rapid access, either IV or IO. Obtain blood glucose. Closely look for signs of ingestion or toxidrome (Anticholinergic vs. Sympathomimetic).

– If agitated/combative, begin with show of force and verbal de-escalation if possible. If patient altered or not cooperative, chemical sedation with IM or IV benzodiazepines will be required. Ketamine IM is a great option for rapid control. Butyrephenones are not recommended but may be used.

Provide IV fluids for rehydration and resuscitation.

– If concern for infection/sepsis present, provide antibiotics and obtain cultures. LP may be warranted, but the patient requires sedation and resuscitation first (this test can be delayed).

Toxicology Examination: VS, pupils, voice/speech, hair, nails, skin, bowel sounds, presence of sweat (upper lip, groin, axillae), presence of urinary retention.

– Obtain ECG, renal function panel, liver function panel, UA, ECG, TSH, coagulation panel, acetaminophen, salicylates, CK, portable chest x-ray, head CT for altered patients.

– If intubating, avoid succinylcholine, which may further elevate potassium levels. Rocuronium is likely safer.

– Disposition based on patient presentation, underlying etiology, hemodynamic status, and management required.


Extra: Heat stroke/heat exhaustion (primary difference is neurologic system involvement in heat stroke)

– Treat by removing clothes, tepid sprays with fans, ice packs to axillae/groin/neck. Immersion is effective, but beware in sick and older patients. Invasive treatments such as lavage and intravascular cooling catheters can be used for severe cases. Avoid NSAIDs and aspirin. Continuous core temperature monitoring recommended for heat stroke.



  1. Simon H. Hyperthermia. N Engl J Med.1993; 329:483-487.
  2. LoVecchio F. Chapter 210: Heat Emergencies. In: Tintinalli J, ed. Tintinalli’s Emergency Medicine. 8th McGraw Hill; 2016: 1365-1370.
  3. Boyer E and Shannon M. The Serotonin Syndrome. N Engl J Med. 2005; 352:1112-1120.
  4. Vassallo SU, Delaney KA. Thermoregulatory Principles. In: Hoffman RS, Howland M, Lewin NA, Nelson LS, Goldfrank LR. eds. Goldfrank’s Toxicologic Emergencies, 10e. New York, NY: McGraw-Hill; 2015
  5. Costrini A. Emergency treatment of exertional heatstroke and comparison of whole body cooling techniques. Med Sci Sports Exerc. 1990;22:15–18.
  6. https://lifeinthefastlane.com/ccc/hyperthermia-associated-toxidromes/

Leave a Reply

Your email address will not be published. Required fields are marked *