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Hypothermia

Will Chapleau EMT-P, RN, TNS

Chicago Heights Fire Department, Chicago Heights, Illinois, USA

   Hypothermia is certainly a special challenge in resuscitation. The challenge is in both the assessment and treatment phase.

   First off, severely hypothermic patients may appear to be clinically dead due to severe depression of respiratory, circulatory and cerebral function.

   The patient may be breathing, but to weak and slow to perceive at first inspection. The peripheral circulation may be restricted and the heart rate so slow that it is missed if taken quickly.

   Secondly, hypothermic patients that are indeed in need of resuscitation, should be resuscitated with special attention to the effect hypothermia has on their body and it's systems, and how conventional therapy's may be affected by this condition.

   The good news is that occasionally, there are spectacular success stories where hypothermic patients have been successfully resuscitated after being pulse less and non-breathing for extended periods of time. This has been particularly true in cold water drowning cases.

   According to the American Heart Association, patients with core temperatures of 30 degrees centigrade or less are said to be severely hypothermic. At this level cerebral blood flow and oxygen requirements are depressed along with cardiac output and arterial pressure. As mentioned earlier, there may be respirations and pulses but they are so weak and slow they are imperceptible. In any event, lifesaving measure should never be withheld due to this potential but it is important to get this patient to a center for re-warming.

   Non-breathing hypothermic patients should be ventilated immediately. Preferably with warm, humidified oxygen. Before beginning compressions though, pulses should be checked for 30-45 seconds.

   During the assessment and resuscitation of the hypothermic patient, prevention of further heat loss and re-warming is important. As soon as possible the patient should be placed in a warm environment and any wet clothing should be removed and the patient covered with dry warm linens. For patients that hypothermic and do not require resuscitation, warm packs under the arms, around the groin and neck, are helpful in helping to re-warm the patient. Remember when moving hypothermic patients they should be handled gently to the potential to induce ventricular fibrillation. Transporting the patient supine will also limit aggravating or inducing hypo tension.

   There have been papers published that recommend withholding compressions, medications, and electric therapies in severely hypothermic patients. While the Heart Association still advices immediate defibrillation when patients are found to be in v-fib, it should also be noted that it may not be possible to convert patients with core temperatures of less than 30 degrees centigrade. Literature seems to support that re-warming enhances success here.

   The American College of Surgeons in the 1997 version of the ATLS text, recommends that patients need to be at least 28 degrees centigrade before drugs and defibrillation are used.

   You may have heard sayings like "They aren't dead till they're dead at room temperature" or they aren't dead until they're warm and dead". In any event, many feel that resuscitation should continue until the patient remains unresponsive to resuscitation at near normal temperatures. Again, there are many stories of cold water drowning victims that recovered after re-warming and resuscitation, even with extended down times. Some down for as long as a half an hour or more. Daniel F. Danza, In the text "Emergency Medicine" states "Resuscitation should be continued until either failure after hospital re-warming to 35 degrees centigrade or danger through exposure to rescuers exists.

   One factor that may contribute to whether or not the patient is resuscable is whether the arrest was before or after the patient became hypothermic. Did the cardiac event precede the drop in temperature or did the hypothermia cause the arrest?

   Earlier, I mentioned that you need to consider what brought your patient to this place. Did the coronary happen first. Environment is also a consideration. Hypothermia in city-dwellers often involves drugs and alcohol. There may be trauma underlying the hypothermia.

   Re-warming of patients that do not require CPR should done with passive re-warming. Dry warmed blankets, with the patient in a warm environment, warmed IV fluids are all recommended by the ACS. They go on to say that severely hypothermic patients may require "active core re-warming techniques which may include peritoneal lavage, thoracic/pleural lavage, hemodialysis, or bypass machines.

REFERENCES

Emergency Medicine, Rosen, MOSBY Publishing, 1983

Basic Life Support for Healthcare Providers, American Heart Association, 1994

ATLS, American College of Surgeons Committee on Trauma, 1997

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2nd Virtual Congress of Cardiology

Dr. Florencio Garófalo
Steering Committee
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Dr. Raúl Bretal
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