An Unresponsive 38-Year-Old Man

Lars Grimm, MD, MHS; Malkeet Gupta, MS, MD; Joshua M. Kosowsky, MD

Disclosures

March 15, 2016

Cardiac reserve is decreased in hypothermic patients and, therefore, judicious volume resuscitation is advised. Cardiac arrhythmia can occur as a consequence of hypothermia, and treatment of cardiac arrhythmia may differ in hypothermic patients. Rewarming the patient is typically sufficient for him or her to regain normal myocardial contractility and rhythm. For patients in shock who do not respond to rewarming and resuscitation with intravenous fluid, low-dose dopamine is the recommended agent because of its inotropic and peripheral vasoconstrictive effects.

Atrial dysrhythmia is generally associated with a slow ventricular response; therefore, treatment with digoxin or calcium-channel blockers is not warranted. Bretylium has long been recommended for the treatment and prevention of ventricular dysrhythmias, although little evidence supports this practice and this agent is no longer available for clinical use. In the case of ventricular arrhythmias, amiodarone is a reasonable choice.

For refractory bradydysrhythmia, external noninvasive pacing is recommended as a first-line treatment. Transvenous pacing may provoke ventricular dysrhythmias with the insertion of pacing wires into a hypothermic ventricle; however, this concern should not limit its use if transcutaneous and pharmacologic therapies are ineffective.[3]

There are three general types of rewarming techniques: passive external, active external, and active internal. Passive external rewarming is reserved for mildly hypothermic patients and involves insulating the patient to allow the intact thermoregulatory mechanisms to reheat the body. Covering the patient in blankets and having him or her inspire humidified air allows slow, steady increases in core body temperature.

Active external rewarming techniques include warm-water immersion, the use of forced-air warming systems, or the placement of a patient in a heat cradle. A major complication of active external warming to be aware of is core temperature afterdrop, in which cold peripheral blood rapidly returns to the heart, leading to inaccurate temperature readings and subsequent inappropriate management decisions.

Active internal rewarming is reserved for severe hypothermia or for patients who do not respond to less aggressive measures.

The rewarming techniques can be classified as either minimally invasive (eg, heated, humidified air and warm intravenous fluids) or more invasive (eg, body cavity lavage, hemodialysis, cardiopulmonary bypass, and extracorporeal blood warming). The choice of the most appropriate rewarming technique is based on the equipment available and the experience of the operator; however, the least invasive means of adequate rewarming is generally best. No concrete evidence suggests that faster rates of rewarming lead to improved outcomes, because comorbidities are the best predictors of mortality. In general, mild or moderate hypothermic patients have an excellent chance of recovery, but patients with severe hypothermia have a mortality rate of roughly 50%.[1,3]

The patient in this case was determined to have moderate hypothermia and was immediately stripped of his clothes. He was given a mask with warm, humidified air to breathe, and warm intravenous fluids were administered. A forced-air blanket was used to cover his torso, and warmed blankets were wrapped around his extremities. Peritoneal lavage with warm saline was started, and the patient's core body temperature began to steadily rise. The ECG changes resolved, the patient's volume status returned to normal, and the body temperature returned to a normal range.

The patient was admitted for monitoring and initiation of treatment of his right lower lobe pneumonia. Eventually, he was discharged without any major disabilities.

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