Hypothermia in adults: A strategy for detection and Tx

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Applied Evidence

Hypothermia in adults: A strategy for detection and Tx

J Fam Pract. 2018 May;67(5):E1-E7

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References

1. McCullough L, Arora S. Diagnosis and treatment of hypothermia. Am Fam Physician. 2004;70:2325-2332.

2. Durrer B, Brugger H, Syme D; International Commission for Mountain Emergency Medicine. The medical on-site treatment of hypothermia: ICAR-MEDCOM recommendation. High Alt Med Biol. 2003;4.

3. Rischall ML, Rowland-Fisher A. Evidence-based management of accidental hypothermia in the emergency department. Emerg Med Pract. 2016;18:1-18.

4. Study: Hypothermia-related deaths—United States, 2003-2004. Atlanta, GA: Centers for Disease Control and Prevention; 2005. Available at: www.cdc.gov/media/pressrel/fs050224.htm. Accessed March 1, 2018.

5. Baumgartner EA, Belson M, Rubin C, et al. Hypothermia and other cold-related morbidity emergency department visits: United States, 1995-2004. Wilderness Environ Med. 2008;19:233-237.

6. Centers for Disease Control and Prevention. Preventing injuries associated with extreme cold. Int J Trauma Nurs. 2001;7:26-30.

7. Jolly BT, Ghezzi KT. Accidental hypothermia. Emerg Med Clin North Am. 1992;10:311-327.

8. Mechem CC. Hypothermia and hyperthermia. In: Lanken PN, Manaker S, Hanson CW III, eds. The Intensive Care Unit Manual. Philadelphia: WB Saunders; 2000.

9. Weinberg AD. Hypothermia. Ann Emerg Med. 1993;22:370-377.

10. Zafren K, Giesbrecht GG, Danzl DF, et al. Wilderness Medical Society practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia. Wilderness Environ Med. 2014;25:425-445.

11. Web-based integrated 2010 & 2015 guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Part 10: Special Circumstances of Resuscitation. Dallas, TX: American Heart Association; 2017. Available at: https://eccguidelines.heart.org/index.php/circulation/cpr-ecc-guidelines-2/part-10-special-circumstances-of-resuscitation. Accessed March 1, 2018.

12. Brown DJ, Brugger H, Boyd J, et al. Accidental hypothermia. N Engl J Med. 2012;367:1930-1938.

13. Petrone P, Asensio JA, Marini CP. Management of accidental hypothermia and cold injury. Curr Probl Surg. 2014;51:417-431.

14. Fudge J. Preventing and managing hypothermia and frostbite injury. Sports Health. 2016;8:133-139.

15. Martin RS, Kilgo PD, Miller PR, et al. Injury-associated hypothermia: an analysis of the 2004 National Trauma Data Bank. Shock. 2005;24:114-118.

Laboratory evaluation. No specific laboratory tests are needed to diagnose hypothermia. General lab tests, however, may help determine whether hypothermia is the result, or the cause, of the clinical scenario. Recommended laboratory tests for making that determination include a complete blood count (CBC), chemistry panel, arterial blood gases, fingerstick glucose, and coagulation panel.

General lab tests may help determine whether hypothermia is the result, or the cause, of the clinical scenario.

Results of lab tests may be abnormal because of the body’s decreased core body temperature. White blood cells and platelets in the CBC, for example, may be decreased due to splenic sequestration; these findings reverse with rewarming. With every 1°C (1.8°F) drop in core body temperature, hematocrit increases 2%.³ Sodium, chloride, and magnesium concentrations do not display consistent abnormalities with any core body temperature >25°C (77°F),^3,8 but potassium levels may fluctuate because of acid-base changes that occur during rewarming.¹ Creatinine and creatine kinase levels may be increased secondary to rhabdomyolysis or acute tubular necrosis.¹

Arterial blood gases typically show metabolic acidosis or respiratory alkalosis, or both.⁸Prothrombin time and partial thromboplastin time are typically elevated in vivo, secondary to temperature-dependent enzymes in the coagulation cascade, but are reported normal in a blood specimen that is heated to 37°C (98.6°F) prior to analysis.^1,8

Both hyperglycemia and hypoglycemia can be associated with hypothermia. The lactate level can be elevated, due to hypoperfusion. Hepatic impairment may be seen secondary to decreased cardiac output. An increase in the lipase level may also occur.³

When a hypothermic patient fails to respond to rewarming, or there is no clear source of cold exposure, consider testing for other causes of the problem, including hypothyroidism and adrenal insufficiency (see “Differential diagnosis”). Hypothermia may also decrease thyroid function in people with preexisting disease.

Other laboratory studies that can be considered include fibrinogen, blood-alcohol level, urine toxicology screen, and blood and fluid cultures.³

Imaging. Imaging studies are not performed routinely in the setting of hypothermia; however:

Chest radiography can be considered to assess for aspiration pneumonia, vascular congestion, and pulmonary edema.
Computed tomography (CT) of the head is helpful in the setting of trauma or if mental status does not clear with rewarming.³
Bedside ultrasonography can assess for cardiac activity, volume status, pulmonary edema, free fluid, and trauma. (See "Point-of-care ultrasound: Coming soon to primary care?" J Fam Pract. 2018;67:70-80.)

Hypothermia in adults: A strategy for detection and Tx

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