Hypothermia

around a hypothermic patient.

Although many texts suggest that intravenous fluids be heated to 45°C, this temperature choice is based on convenience of previous study designs rather than any hard evidence. A trial using fluids heated to 65°C demonstrated more efficacy in treating severe hypothermia. Emergency departments that routinely treat hypothermia can keep blankets and intravenous fluid bags in a shared heater. In urgent situations, intravenous fluids that contain no dextrose or blood can be heated in a microwave oven. Once these simple measures have been applied, consider more difficult rewarming therapies.

Optimal rewarming techniques depend upon a patient's condition. Treatment is often limited by hospital availability and physician inexperience with rewarming approaches. If core body temperature does not respond to warming efforts, underlying infection or endocrine derangements must be considered.

A patient who is not becoming progressively colder, is conscious, and has a perfusing cardiac rhythm may not require intensive intervention beyond the methods already discussed.

Debate centers on interventions for patients who are worsening, are comatose, have nonperfusing rhythms, or appear dead. Most texts advocate aggressive therapy for severely hypothermic patients, basing the recommendation on anecdotal reports of success.

Researchers recently confirmed justification for aggressive treatment in a 16-year longitudinal review of profound hypothermia. In this series of 32 Swiss patients presenting with hypothermia and cardiac arrest, 15 patients were resuscitated with aggressive techniques, and all 15 patients showed full neurologic recovery.

In an older review, rewarming at rates faster than 2°C/h was noted to reduce mortality when compared with slower rates.

An optimal warming strategy is elusive. Some have postulated that rapidly warming a patient to 33°C and maintaining him or her at that temperature, using hypothermia therapeutically as though he or she was a cardiac arrest patient might be beneficial.

For simplicity, aggressive rewarming methods can be categorized as slow, moderate, or rapid. Slow rewarming provides heat from 17-30 kcal/h, corresponding to increasing temperature by 0.3-1.2°C/h. (Comparisons are somewhat difficult since different study groups used different measurements of heat gain.) Slow rewarming methods include IV solutions heated to 45°C (17 kcal/h); heated, humidified oxygen by mask (30 kcal/h or 0.7°C/h); warmed blankets (0.9°C/h); and heated, humidified oxygen via endotracheal tube (1.2°C/h). If intact, a patient's endogenous physiologic mechanisms (other than shivering) provide similar rates of rewarming (30 kcal/h).

Moderate rewarming methods provide heat at approximately 3°C/h. Methods include warmed gastric lavage (2.8°C/h), intravenous solutions heated to 65°C (2.9°C/h), and peritoneal lavage with 45°C fluid at 4 L/h (70 kcal/h or 3°C/h).

Rapid rewarming methods provide heat at levels higher than 100 kcal/h. Methods include thoracic lavage at 500 mL/min (6.1°C/h), cardiopulmonary bypass (400 kcal/h or 18°C/h), thoracic lavage at 2 L/min (19.7°C/h), ECMO, and AV dialysis (1-4 degrees per hour, and warm-water immersion [1500 kcal/h]).

In comparison, endogenous shivering provides rewarming at a rate of 300 kcal/h. No noninvasive technique rewarms as rapidly as full-body immersion in warm water. Known as the Hubbard tank technique, immersion has successfully rewarmed humans with severe hypothermia. Unfortunately, patients who require rapid rewarming in the emergency department also need cardiac monitoring and intravenous therapy, both of which are difficult to manage under water.

Defibrillation also is difficult; however, defibrillation is likely futile once a patient's core temperature falls below 30°C.

Initiate CPR for hypothermic patients who deteriorate into ventricular fibrillation. These patients also warrant immediate weight-based defibrillation (2 J/kg), along with prompt administration of high-dose bretylium (10 mg/kg).

Consider initiating cardiopulmonary bypass for any case of ventricular fibrillation or profound hypothermia with deterioration. Patients with this degree of hypothermia have optimized outcomes with procedures such as cardiopulmonary bypass and pleural lavage. However, these methods are invasive, often unavailable, and infrequently used and as such are subject to user-inexperience.

Ventricular fibrillation should be treated immediately with defibrillation, despite the fact that most other dysrhythmias will correct with warming alone. If initial attempts at defibrillation are unsuccessful, further attempts at defibrillation and antiarrhythmic intravenous medications should be held until the patient is warmed to above 30°C. During this interval, basic life support is continued. If ventricular fibrillation persists despite rewarming, current AHA guidelines recommend administration of amiodarone.[8, 9]

Although studies in emergency medicine are lacking, cardiothoracic surgeons who induce hypothermia to perform open-heart procedures rewarm patients on a daily basis using open cardiac massage with warmed saline solution. Therefore, a desperate case of severe hypothermia may warrant consideration of direct cardiac rewarming via open emergency department thoracotomy with open cardiac massage.

Cardiothoracic bypass has been used successfully to treat cases of hypothermia presenting in cardiac arrest.[10] To be successful, bypass must be performed rapidly. If a delay is expected, the physician can expedite bypass during an interim period by placing cordis catheters in the patient's femoral vein and artery. Groin cutdowns may be necessary to facilitate such placement; if cutdowns are needed, perform them without hesitation. If bypass is unavailable or delayed, 2 previously described methods of internal rewarming are available: heated thoracic lavage and arteriovenous (AV) heated countercurrent exchange.

The literature describes 2 methods of thoracic lavage; the simplest method uses available equipment and provides rewarming rates equivalent to cardiopulmonary bypass.

The technique involves placing 2 left-sided, 38 French chest tubes (third intercostal space midclavicular line and sixth intercostal space midaxillary line). Isotonic saline, in 3-liter bags heated to at least 41°C, is infused through the anterior tube at 2 L/min, then drained by gravity via the posterior tube. When warmed saline was not available, physicians successfully infused warmed tap water.

The AV heating method, developed at the University of Washington, uses a modified bypass technique for rapid blood rewarming using a level one fluid warmer that is familiar to physicians experienced in trauma resuscitation. The treatment is preferred for patients with profound hypothermia and markedly depressed hemodynamic status or cardiac arrest. AV heating requires a spontaneous pulse, since the patient's intrinsic blood pressure drives flow through the countercurrent module. (In true cardiothoracic bypass, an external pump is built into the machine.) Catheters are placed into the femoral artery and venous cordis.

Once catheters are placed, the arterial output is connected to the inflow port of a level one countercurrent warmer, where intravenous fluids are connected. The outflow port is connected to the femoral venous catheter. Water is circulated, at a temperature preset on the level one device, around the blood-containing tubing; the blood warms as it flows through the countercurrent module. The AV method has rewarmed profoundly hypothermic patients 5 times more rapidly (39 min vs 199 min) than standard methods and was demonstrated to decrease the mortality rate.

In an alternative endovascular warming technique,[11] a catheter is advanced into the inferior vena cava and circulates warmed fluids. The catheter acts as indwelling radiator as it is connected to an esophageal temperature probe and uses a feedback loop to attain and maintain programmed patient temperature. By this method, the core body temperature may be elevated at a rate of 3 degrees an hour. Additionally, it is an invasive technique to raise core temperature that utilizes skills that emergency physicians are already well trained and comfortable with.

Vasodilation increases the vascular space; consequently, patients that have been hypothermic for more than 45-60 minutes often require fluid administration. Hypotension should be addressed with volume resuscitation; inotropic agents, such as dopamine, should be avoided unless the hypotension is refractory to intravenous fluids due to the possible cardiac stimulation/ectopy that pressors may induce.

Probes for pulse oximetry placed on the ears or the forehead appear to be less influenced by the peripheral vasoconstriction of the digits associated with decreased body temperature.

Assessment should include a total body survey to exclude local cold-induced injuries.

Special concerns

Controversy surrounds the issue of pronouncing death in a hypothermic patient.

A reasonable approach is to initiate resuscitation on all hypothermic patients unless a patient presents with a frozen chest or other obvious nonsurvivable injuries. A patient can be warmed aggressively and resuscitated until the core temperature rises above 32°C. At that juncture, if no signs of life are present and the patient is not responding to advanced cardiac life support measures, termination of resuscitation may be indicated.

Individual clinical judgment is paramount in these settings, and variables, such as the patient's age and any comorbid conditions, must be taken into account. Serum potassium levels may be useful in determining when to cease resuscitation; patients with potassium levels of 10 mmol/L or higher have very poor outcomes.

Clearly, profound hypothermia can mimic clinical death. However, patients with profound hypothermia can be resuscitated successfully with good neurologic outcomes. The adage that "a patient is not dead until they are warm and dead" is of some use.

In some cases, prologed efforts to bring a patient with no signs of life to a normal body temperature canbe futile. If a patient's chest is frozen, resuscitative efforts are not necessary.

Contributor Information and Disclosures

Author

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

Disclosure: Nothing to disclose.

Coauthor(s)

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 is a member of the following medical societies: American College of Emergency Physicians, Society for Academic Emergency Medicine, Council of Emergency Medicine Residency Directors, American Medical Association

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.

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.

References

1.Polderman KH. Mechanisms of action, physiological effects, and complications of hypothermia. Crit Care Med. 2009 Jul. 37(7 Suppl):S186-202. [Medline].

2.Long WB 3rd, Edlich RF, Winters KL, Britt LD. Cold injuries. J Long Term Eff Med Implants. 2005. 15(1):67-78. [Medline].

3.Sessler DI. Thermoregulatory defense mechanisms. Crit Care Med. 2009 Jul. 37(7 Suppl):S203-10. [Medline].

4.Centers for Disease Control and Prevention. Number of Hypothermia-Related Deaths, by Sex - National Vital Statistics System, United States, 1999–2011. Available at http://www.cdc.gov/mmwr/preview/mmwrhtml /mm6151a6.htm. Accessed: August 22, 2014.

5.McCullough L, Arora S. Diagnosis and treatment of hypothermia. Am Fam Physician. 2004 Dec 15. 70(12):2325-32. [Medline].

6.Buckley JJ, Bosch OK, Bacaner MB. Prevention of ventricular fibrillation during hypothermia with bretylium tosylate. Anesth Analg. 1971 Jul-Aug. 50(4):587-93. [Medline].

7.Murphy K, Nowak RM, Tomlanovich MC. Use of bretylium tosylate as prophylaxis and treatment in hypothermic ventricular fibrillation in the canine model. Ann Emerg Med. 1986 Oct. 15(10):1160-6. [Medline].

8.[Guideline] ECC Committee, Subcommittees and Task Forces of the American Heart Association. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010 Nov. 122(18):Suppl 3.

9.Brown DJ, Brugger H, Boyd J, Paal P. Accidental hypothermia. N Engl J Med. 2012 Nov 15. 367(20):1930-8. [Medline].

10.Boué Y, Payen JF, Brun J, Thomas S, Levrat A, Blancher M, et al. Survival after avalanche-induced cardiac arrest. Resuscitation. 2014 Sep. 85(9):1192-6. [Medline].

11.Laniewicz M, Lyn-Kew K, Silbergleit R. Rapid endovascular warming for profound hypothermia. Ann Emerg Med. 2008 Feb. 51(2):160-3. [Medline].

12.Abella BS, Rhee JW, Huang KN, Vanden Hoek TL, Becker LB. Induced hypothermia is underused after resuscitation from cardiac arrest: a current practice survey. Resuscitation. 2005 Feb. 64(2):181-6. [Medline].

13.Alam HB, Rhee P, Honma K, et al. Does the rate of rewarming from profound hypothermic arrest influence the outcome in a swine model of lethal hemorrhage?. J Trauma. 2006 Jan. 60(1):134-46. [Medline].

14.Casas F, Alam H, Reeves A, Chen Z, Smith WA. A portable cardiopulmonary bypass/extracorporeal membrane oxygenation system for the induction and reversal of profound hypothermia: feasibility study in a Swine model of lethal injuries. Artif Organs. 2005 Jul. 29(7):557-63. [Medline].

15.Elbaz G, Etzion O, Delgado J, Porath A, Talmor D, Novack V. Hypothermia in a desert climate: severity score and mortality prediction. Am J Emerg Med. 2008 Jul. 26(6):683-8. [Medline].

16.Headdon WG, Wilson PM, Dalton HR. The management of accidental hypothermia. BMJ. 2009 Jun 10. 338:b2085. [Medline].

17.Jurkovich GJ. Environmental cold-induced injury. Surg Clin North Am. 2007 Feb. 87(1):247-67, viii. [Medline].

18.Launay JC, Savourey G. Cold adaptations. Ind Health. 2009 Jul. 47(3):221-7. [Medline].

19.Schewe JC, Heister U, Fischer M, Hoeft A. [Accidental urban hypothermia. Severe hypothermia of 20.7 degrees C]. Anaesthesist. 2005 Oct. 54(10):1005-11. [Medline].

20.Spencer SM, Roeseler J, Verschuren F, Reynaert M, Thys F. Metabolism study in an 88-year-old woman with severe hypothermia during rewarming procedures. Am J Emerg Med. 2007 Oct. 25(8):986.e1-3. [Medline].

21.Windsor JS, Firth PG, Grocott MP, Rodway GW, Montgomery HE. Mountain mortality: a review of deaths that occur during recreational activities in the mountains. Postgrad Med J. 2009 Jun. 85(1004):316-21. [Medline].

Medscape Reference © 2011 WebMD, LLC

Hypothermia Workup

Author: James Li, MD; Chief Editor: Joe Alcock, MD, MS more...

Updated: Aug 25, 2014

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

Author

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

Disclosure: Nothing to disclose.

Coauthor(s)

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 is a member of the following medical societies: American College of Emergency Physicians, Society for Academic Emergency Medicine, Council of Emergency Medicine Residency Directors, American Medical Association

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.

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.

References

1.Polderman KH. Mechanisms of action, physiological effects, and complications of hypothermia. Crit Care Med. 2009 Jul. 37(7 Suppl):S186-202. [Medline].

2.Long WB 3rd, Edlich RF, Winters KL, Britt LD. Cold injuries. J Long Term Eff Med Implants. 2005. 15(1):67-78. [Medline].

3.Sessler DI. Thermoregulatory defense mechanisms. Crit Care Med. 2009 Jul. 37(7 Suppl):S203-10. [Medline].

4.Centers for Disease Control and Prevention. Number of Hypothermia-Related Deaths, by Sex - National Vital Statistics System, United States, 1999–2011. Available at http://www.cdc.gov/mmwr/preview/mmwrhtml /mm6151a6.htm. Accessed: August 22, 2014.

5.McCullough L, Arora S. Diagnosis and treatment of hypothermia. Am Fam Physician. 2004 Dec 15. 70(12):2325-32. [Medline].

6.Buckley JJ, Bosch OK, Bacaner MB. Prevention of ventricular fibrillation during hypothermia with bretylium tosylate. Anesth Analg. 1971 Jul-Aug. 50(4):587-93. [Medline].

7.Murphy K, Nowak RM, Tomlanovich MC. Use of bretylium tosylate as prophylaxis and treatment in hypothermic ventricular fibrillation in the canine model. Ann Emerg Med. 1986 Oct. 15(10):1160-6. [Medline].

8.[Guideline] ECC Committee, Subcommittees and Task Forces of the American Heart Association. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010 Nov. 122(18):Suppl 3.

9.Brown DJ, Brugger H, Boyd J, Paal P. Accidental hypothermia. N Engl J Med. 2012 Nov 15. 367(20):1930-8. [Medline].

10.Boué Y, Payen JF, Brun J, Thomas S, Levrat A, Blancher M, et al. Survival after avalanche-induced cardiac arrest. Resuscitation. 2014 Sep. 85(9):1192-6. [Medline].

11.Laniewicz M, Lyn-Kew K, Silbergleit R. Rapid endovascular warming for profound hypothermia. Ann Emerg Med. 2008 Feb. 51(2):160-3. [Medline].

12.Abella BS, Rhee JW, Huang KN, Vanden Hoek TL, Becker LB. Induced hypothermia is underused after resuscitation from cardiac arrest: a current practice survey. Resuscitation. 2005 Feb. 64(2):181-6. [Medline].

13.Alam HB, Rhee P, Honma K, et al. Does the rate of rewarming from profound hypothermic arrest influence the outcome in a swine model of lethal hemorrhage?. J Trauma. 2006 Jan. 60(1):134-46. [Medline].

14.Casas F, Alam H, Reeves A, Chen Z, Smith WA. A portable cardiopulmonary bypass/extracorporeal membrane oxygenation system for the induction and reversal of profound hypothermia: feasibility study in a Swine model of lethal injuries. Artif Organs. 2005 Jul. 29(7):557-63. [Medline].

15.Elbaz G, Etzion O, Delgado J, Porath A, Talmor D, Novack V. Hypothermia in a desert climate: severity score and mortality prediction. Am J Emerg Med. 2008 Jul. 26(6):683-8. [Medline].

16.Headdon WG, Wilson PM, Dalton HR. The management of accidental hypothermia. BMJ. 2009 Jun 10. 338:b2085. [Medline].

17.Jurkovich GJ. Environmental cold-induced injury. Surg Clin North Am. 2007 Feb. 87(1):247-67, viii. [Medline].

18.Launay JC, Savourey G. Cold adaptations. Ind Health. 2009 Jul. 47(3):221-7. [Medline].

19.Schewe JC, Heister U, Fischer M, Hoeft A. [Accidental urban hypothermia. Severe hypothermia of 20.7 degrees C]. Anaesthesist. 2005 Oct. 54(10):1005-11. [Medline].

20.Spencer SM, Roeseler J, Verschuren F, Reynaert M, Thys F. Metabolism study in an 88-year-old woman with severe hypothermia during rewarming procedures. Am J Emerg Med. 2007 Oct. 25(8):986.e1-3. [Medline].

21.Windsor JS, Firth PG, Grocott MP, Rodway GW, Montgomery HE. Mountain mortality: a review of deaths that occur during recreational activities in the mountains. Postgrad Med J. 2009 Jun. 85(1004):316-21. [Medline].

Medscape Reference © 2011 WebMD, LLC

Hypothermia Follow-up

Author: James Li, MD; Chief Editor: Joe Alcock, MD, MS more...

Updated: Aug 25, 2014

Further Inpatient Care

Medical complications from hypothermia often result and necessitate admission to the hospital in moderate and severe hypothermia. Severely hypothermic patients should be admitted to an intensive care unit where their respiratory and cardiac function and temperature may be closely monitored.

Acute pulmonary edema should be treated with oxygen, empirical antibiotics for aspiration pneumonia, and diuretics as necessary.

Frostbite and other localized cold injuries result in deep tissue damage. Surgical exploration and debridement may be necessary. Affected body parts may have to be amputated if gangrene develops. Such a procedure is usually performed at some delayed time interval once a line of demarkation has declared itself days to weeks later.

The development of rhabdomyolysis should be monitored.

Deterrence/Prevention

Preparation is key to avoiding accidental hypothermia. Appropriate cold weather clothing and survival bags are a necessity if walking or climbing in a cold climate.

Persons should avoid alcohol if anticipating exposure to cold because alcohol can disrupt temperature homeostasis by causing vasodilation. Individuals should remain alert to early symptoms and initiate preventive measures (eg, drinking warm fluids).

Adequate heat in the home should be maintained. Patients should be referred to a social service agency for help with adequate housing, heat, and/or clothing.

Complications

Complications of hypothermia

See the list below:

Cardiac arrhythmias at temperatures below 30-32°C

Infection

Aspiration pneumonia

Pulmonary edema

Pancreatitis

Bleeding diathesis

Bladder atony

Frostbite

Electrolyte (hyperkalemia, hypoglycemia), hematocrit, coagulation study abnormalities

Complications of treatment of hypothermia

See the list below:

Rewarming shock, or hypotension secondary to marked vasodilatation of rewarming

Rewarming acidosis due to recirculation of pooled lactic acid in the peripheral circulation

Rewarming electrolyte disturbances, in particular hypocalcemia and hypomagnesemia, indicate a poor prognosis

Aspiration pneumonia

Pulmonary edema

Pancreatitis

Burns to cold and vasoconstricted skin secondary to application of hot water bottles and heating pads

Neutropenia, thrombocytopenia, and infection

Iatrogenic hyperthermia

Ventricular fibrillation

Peritonitis

GI bleeding

Acute tubular necrosis

Intravascular thrombosis

Metabolic acidosis

Rhabdomyolysis

Gangrene Compartment syndrome

Prognosis

The risk of morbidity and mortality depends on the severity of the degree of hypothermia and the underlying cause. Recovery is usually complete for previously healthy individuals with mild or moderate hypothermia (mortality rate < 5%). The mortality rate for patients with severe hypothermia, especially with preexisting illness, may be higher than 50%.

Patient Education

For patient education resources, see the First Aid and Injuries Center. Also, see the patient education article Hypothermia.

Contributor Information and Disclosures

Author

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

Disclosure: Nothing to disclose.

Coauthor(s)

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 is a member of the following medical societies: American College of Emergency Physicians, Society for Academic Emergency Medicine, Council of Emergency Medicine Residency Directors, American Medical Association

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.

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.

References

1.Polderman KH. Mechanisms of action, physiological effects, and complications of hypothermia. Crit Care Med. 2009 Jul. 37(7 Suppl):S186-202. [Medline].

2.Long WB 3rd, Edlich RF, Winters KL, Britt LD. Cold injuries. J Long Term Eff Med Implants. 2005. 15(1):67-78. [Medline].

3.Sessler DI. Thermoregulatory defense mechanisms. Crit Care Med. 2009 Jul. 37(7 Suppl):S203-10. [Medline].

4.Centers for Disease Control and Prevention. Number of Hypothermia-Related Deaths, by Sex - National Vital Statistics System, United States, 1999–2011. Available at http://www.cdc.gov/mmwr/preview/mmwrhtml /mm6151a6.htm. Accessed: August 22, 2014.

5.McCullough L, Arora S. Diagnosis and treatment of hypothermia. Am Fam Physician. 2004 Dec 15. 70(12):2325-32. [Medline].

6.Buckley JJ, Bosch OK, Bacaner MB. Prevention of ventricular fibrillation during hypothermia with bretylium tosylate. Anesth Analg. 1971 Jul-Aug. 50(4):587-93. [Medline].

7.Murphy K, Nowak RM, Tomlanovich MC. Use of bretylium tosylate as prophylaxis and treatment in hypothermic ventricular fibrillation in the canine model. Ann Emerg Med. 1986 Oct. 15(10):1160-6. [Medline].

8.[Guideline] ECC Committee, Subcommittees and Task Forces of the American Heart Association. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010 Nov. 122(18):Suppl 3.

9.Brown DJ, Brugger H, Boyd J, Paal P. Accidental hypothermia. N Engl J Med. 2012 Nov 15. 367(20):1930-8. [Medline].

10.Boué Y, Payen JF, Brun J, Thomas S, Levrat A, Blancher M, et al. Survival after avalanche-induced cardiac arrest. Resuscitation. 2014 Sep. 85(9):1192-6. [Medline].

11.Laniewicz M, Lyn-Kew K, Silbergleit R. Rapid endovascular warming for profound hypothermia. Ann Emerg Med. 2008 Feb. 51(2):160-3. [Medline].

12.Abella BS, Rhee JW, Huang KN, Vanden Hoek TL, Becker LB. Induced hypothermia is underused after resuscitation from cardiac arrest: a current practice survey. Resuscitation. 2005 Feb. 64(2):181-6. [Medline].

13.Alam HB, Rhee P, Honma K, et al. Does the rate of rewarming from profound hypothermic arrest influence the outcome in a swine model of lethal hemorrhage?. J Trauma. 2006 Jan. 60(1):134-46. [Medline].

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