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Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

Jerry R. Balentine, DO, FACEP

Jerry R. Balentine, DO, FACEP

Dr. Balentine received his undergraduate degree from McDaniel College in Westminster, Maryland. He attended medical school at the Philadelphia College of Osteopathic Medicine graduating in1983. He completed his internship at St. Joseph's Hospital in Philadelphia and his Emergency Medicine residency at Lincoln Medical and Mental Health Center in the Bronx, where he served as chief resident.

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The doctor will first assess for immediate life threats, which are primarily the lack of breathing or a pulse. If the victim is not breathing, he or she will have a tube placed to help them breathe. If the victim does not have a pulse, chest compressions will be started.

If the heart appears on the cardiac monitor to be beating ineffectively (a condition known as ventricular fibrillation), electricity may be applied to the chest using two paddles in an attempt to defibrillate the heart. This procedure may be tried up to three times at first, and then occasionally as the person's temperature begins to climb.

If necessary, a tube will be placed into the trachea to help the patient breathe, and a catheter may be inserted into the bladder to monitor urine output. An IV line will be started, and warmed fluids will be given to treat the dehydration commonly seen in people with hypothermia.

During this time, the process of re-warming is begun. There are three categories of re-warming:

• Passive external re-warming (PER): This method is ideal for mild hypothermia. In order to be effective, the person must be able to generate enough heat to maintain a good rate of spontaneous re-warming. The victim is placed in a suitably warm environment and covered with insulation. Core temperature is expected to increase a few degrees per hour with this method. At a core temperature below 86 F (30 C), spontaneous shivering is lost. The person has no ability to increase his or her own temperature, and PER is ineffective.
• Active external re-warming (AER) is a controversial technique in which heat is applied to the skin. Although common sense would suggest that this would be an effective method of re-warming, it has complications. When applied to the entire body, the warmth causes the brain to dilate the blood vessels in the arms and legs from their highly narrowed state. This action can bring cold blood that was previously trapped in the arms and legs back to the core of the body and actually lower its temperature. This same blood may also carry with it a large amount of toxins, including acids, which can flood the core and cause a dangerous acidosis. For these reasons and others, if AER is employed, it is usually directed over the trunk of the body only. Many clinicians only utilize warm air instead of direct warm compresses with AER.
• Active core re-warming (ACR) is the most effective way to rapidly increase core temperature. It avoids many of the dangers associated with external re-warming. ACR is used when the person's heart is unstable, when body temperature is below 89.9 F (32.2 C), and when the person is re-warming too slowly or not at all or in cases of secondary hypothermia. ACR may be performed in a variety of ways.
  • Airway: Warmed, humidified air is given either through the breathing tube or a closely fitted oxygen mask.
  • Warmed IV fluids are administered
  • Warm fluids are put into the bladder via a Foley catheter
  • Warm fluids are circulated into the peritoneal cavity
  • Peritoneal dialysis: Warmed fluid is placed into the abdomen through an incision and later removed. This cycle is repeated every 20-30 minutes. The major benefit here is that the liver may be quickly rewarmed and thus able to clear the body of toxins.
  • Heated irrigation: Tubes may be placed between the ribs, and heated water applied over the lungs and heart. Its effects are questionable.
  • Diathermy: This is a method in which ultrasound and low-frequency microwave radiation is employed to deliver heat to deeper tissues; it is not used often in environmentally-caused hypothermia.
  • Extracorporeal: Employing one of a variety of methods, blood is circulated from the person's body through a warmer and then back into the bloodstream. This is the most rapid means currently available; however, it is not available in many hospitals.

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