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Hypothermia Workup

  • Author: James Li, MD; Chief Editor: Joe Alcock, MD, MS  more...
Updated: Apr 26, 2016

Laboratory Studies

Arterial blood gas determination includes the following:

  • Blood gas analyzers warm blood to 37°C.
  • Because gasses are less soluble in hypothermic plasma, arterial blood gas (ABG) level may show higher oxygen and carbon dioxide levels and a lower pH than a patient's actual values as the blood is warmed in the ABG machinery.
  • The best approach is to expect uncorrected ABG values compared with the normal values at 37°C.
  • An uncorrected pH at 7.4 and pCO 2 at 40 mm Hg reflect acid-base balance.

Many hypothermic patients are volume contracted because of cold diuresis. As a result, hematocrit level may be deceptively high. Hematocrit levels may increase 2% for each 1°C drop in core temperature.

Hypothermia may present with wide fluctuations in electrolytes, and no clear trend or predictability exists as to when a patient's electrolytes will be abnormal or how large swings may be. Plasma potassium levels can be useful in evaluating prognosis. A level of 10 mmol/L or greater is associated with a very low likelihood of recovery. Classic ECG changes of hyperkalemia may be absent or diminished. Chronic hypothermia occasionally can lead to hypokalemia.

Acute hypothermia can result in hyperglycemia, while chronic hypothermia or secondary hypothermia may present with low blood glucose level.

The body's coagulation mechanism is often disrupted in moderate or severe hypothermia, and a disseminated intervascular coagulation–type syndrome can be present.

Coagulopathy has several causes. The primary issue is disruption of enzymatic reactions of the clotting cascade caused by protein denaturization at decreased temperature.

Because the kinetic tests of coagulation are performed at 37°C in the laboratory, a clinically evident coagulopathy may not be reflected by deceptively normal laboratory values.


Imaging Studies

A chest radiograph is indicated in patients with hypoxia. Aspiration pneumonia and pulmonary edema are common findings.

Patients with trauma or altered mental status of indeterminate cause may need a noncontrast head CT scan and further imaging for a standard trauma evaluation.


Other Tests

The ECG may show prolonged PR, QRS, and QT intervals, and atrial or ventricular arrhythmias. The length and height of the respective QT-interval prolongation and characteristic J (Osborne) waves are often proportional to the degree of hypothermia.

Contributor Information and Disclosures

James Li, MD Former Assistant Professor, Division of Emergency Medicine, Harvard Medical School; Board of Directors, Remote Medicine

Disclosure: Nothing to disclose.


Wyatt Decker, MD Vice President and Chief Executive Officer, Mayo Clinic Campus, Arizona

Wyatt Decker, MD is a member of the following medical societies: American College of Emergency Physicians

Disclosure: Nothing to disclose.

Mark A Silverberg, MD, MMB, FACEP Assistant Professor, Associate Residency Director, Department of Emergency Medicine, State University of New York Downstate College of Medicine; Consulting Staff, Department of Emergency Medicine, Staten Island University Hospital, Kings County Hospital, University Hospital, State University of New York Downstate Medical Center

Mark A Silverberg, MD, MMB, FACEP is a member of the following medical societies: American College of Emergency Physicians, American Medical Association, Council of Emergency Medicine Residency Directors, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Jamie Alison Edelstein, MD Staff Physician, Department of Emergency Medicine, State University of New York, Kings County Hospital Center

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

James Steven Walker, DO, MS Clinical Professor of Surgery, Department of Surgery, University of Oklahoma College of Medicine

James Steven Walker, DO, MS is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Osteopathic Emergency Physicians, American Osteopathic Association

Disclosure: Nothing to disclose.

Chief Editor

Joe Alcock, MD, MS Associate Professor, Department of Emergency Medicine, University of New Mexico Health Sciences Center

Joe Alcock, MD, MS is a member of the following medical societies: American Academy of Emergency Medicine

Disclosure: Nothing to disclose.

Additional Contributors

Dan Danzl, MD Chair, Professor, Department of Emergency Medicine, University of Louisville Hospital

Dan Danzl, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, Kentucky Medical Association, Society for Academic Emergency Medicine, Wilderness Medical Society

Disclosure: Nothing to disclose.

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Osborne (J) waves (V3) in a patient with a rectal core temperature of 26.7°C (80.1°F). ECG courtesy of Heather Murphy-Lavoie of Charity Hospital, New Orleans.
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