Hypothermia on the fireground

   

During a recent cold snap (with temperatures in the teens), your EMS crew responds to a first-alarm assignment in a vacant dwelling in a run-down section of the city. It is a small fire, rubbish in one of the rooms that is knocked down easily. Then the first in company reports they are "Bringing out a victim, who might be dead!"

Because of the small size of the fire your ambulance is close to the building, so they bring him right to the back of the truck. You are presented with a disheveled, middle aged male who is unresponsive. He does in fact look dead, but then he takes a breath. His skin that is exposed is very cold and you suspect he is quite hypothermic.

Hypothermia, or a core body temperature of less than 95 F (98.6 F is normal), is rare among emergency responders, so it will not be found among our staff in the rehab sector as much as localized cold injury such as frostbite

Civilians at risk
However, we will encounter and treat civilians with hypothermia, even if you work in the South or other more temperate environments. Even patients in private homes and nursing homes can suffer from lower-than-normal temperatures.

There are a number of factors that can place a patient at risk for hypothermia. The urban poor or homeless are certainly susceptible. Many do not want to go to shelters and will try to survive on their own.

Elderly are at risk for a number of reasons they may not sense the cold as well, they may have various medical conditions (thyroid problems for example) that limit their ability to respond to cold, and they may make a decision to lower their heat due to financial problems.

Any patient with an altered mental status, such as alcohol or drug intoxication, stroke or trauma, is also at higher risk.

Clinically, as the body temperature drops, the patient will experience different conditions:

Levels of severity
Mild Hypothermia (90 to 95 F): Increase in respiratory rate and heart rate, shivering is present in an attempt to generate more body heat, speech and fine motor control may become slightly difficult. The blood vessels to the skin are constricted in an attempt to conserve heat.

Moderate Hypothermia (82-90 F): Shivering stops and the patient begins to have an altered mental status. Heart rate drops. If a 12-Lead EKG is done, Osborn or "J-waves" may be noted.

Severe Hypothermia (<82 F): At this point the patient is likely unconscious, they are not able to control their airway and they are at risk for having their heart rhythm degenerate into ventricular fibrillation.

Treating hypothermia
Treatment of patients that are hypothermic is supportive meaning from a pre-hospital standpoint, we want to make sure things do not get worse, and support their condition until we get to the hospital. This problem did not develop over 15 minutes, and we are not going to solve it in 15 minutes.

As always, start with the ABCs. Does the patient need to have an oral or nasal airway placed? If they are not breathing, start bag-valve-mask ventilations. Check for a pulse, but understand that the heart rate may be very slow and difficult to detect. Do not delay care. If there are no signs of life, then start CPR.

In the past, if the patient was in ventricular fibrillation, we often administered a limited number of shocks and then waited until the temperature was raised to a certain level before administering additional attempts at defibrillation. In the most recent AHA 2010 Emergency Cardiac Care Guidelines, there is a discussion that it may be better to continue with standard care, defibrillating normally, even in a cold patient.

Similarly, for advanced providers, it was previously recommended to withhold emergency medications that are typically used in a cardiac arrest until the temperature is above 86 F. It is thought that these medications would not be metabolized normally and could build up to toxic levels if they are administered while the patient is still hypothermic.

The new guidelines also question this approach to be blunt, we just don't know. The AHA is leaving this as a local decision. Discuss this with your medical director and of course follow local protocol.

My personal opinion is that it is likely better to just do good, quality CPR while transporting to a hospital that can work to warm the patient. ACLS drugs have never really been proven to make a difference in warm patients so they are unlikely to make a difference in hypothermic ones. Defibrillation can be attempted along normal protocols as long as it does not interfere with good CPR, just as in warm patients.

Patients without cardiac arrest
But let's look at the patient that has not suffered a cardiac arrest. Consider other problems and issues.

Did the patient suffer any trauma? We need to get their clothes off and do a good assessment looking for injuries. Consider the surroundings do we need to stabilize the spine because of the possibility of a fall or other cervical trauma? As we take off their clothes we may actually be helping as well, especially if the clothes are wet. Once we do a primary exam followed by a good head to toe exam, cover exposed skin with dry blankets.

Provide warmed oxygen and transport gently. The heart is more sensitive when cold and ventricular fibrillation could be caused by rough movement. You could consider wrapping hot packs in a towel and placing in the axilla (armpit) and groin (as these are where major vessels are near the skin, but it probably won't make much difference in the short term. Ensure the ambulance heat is turned up if you are comfortable wearing your uniform and coat then it is too cold in the back.

There is a concern about warming the extremities before the trunk of the body. The body has constricted the blood vessels to the extremities and this acts to maintain the blood pressure in a hypovolemic patient. If we warm the extremities first, these vessel will dilate and blood volume will return to the extremities too quickly and before the patient's volume status has been addressed. This will cause the blood pressure to drop. So, concentrate on the trunk first, although don't leave the extremities exposed to the air.

Notify the destination hospital and transport safely. Remember, saving five minutes by racing through the city at unsafe speeds for a patient that has been out in the cold all night is a little silly. Arrive safely.

Hypothermia can occur anywhere (and anytime, even summer) certainly outside, but also inside a building that to us seems warm. Always consider the possibility, and at least start the process of trying to warm them passively with blankets and heat.

By Dr. Ken Lavelle, MD, NREMT-P
Fireground Medical Operations
by Albert Einstein Medical Center
Sponsored by FireRehab.com

   

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