Download 1st Quarter – Hypothermia Packet

Aurora Health Care
EMS Continuing Education
1st Quarter 2013 Packet
Hypothermia
We all understand that hypothermia occurs when the patient’s core temperature drops
secondary to exposure to cold. But, clinically, what is hypothermia really? What happens
to the body as it cools down and struggles to maintain its core temperature? Can we
predict a patient’s relative core temperature based on our physical findings? Is treatment
really as simple as bringing them in and warming them up?
Let’s review the basics of the hypothermia progression and explore how to treat these
sometimes challenging patient presentations.
When we consider the typical hypothermia victim we often envision the lost hiker
stumbling through the snowy woods looking for home. Perhaps our victim stumbles
through a freezing stream, the sun begins to set and hypothermia sets in.
No doubt, our lost hiker is at risk for hypothermia, but we should consider that anything
that decreases the body’s ability to produce heat or increases the body’s propensity to
lose heat, can lead to eventual hypothermia. The prepared hiker may be less at risk for
hypothermia than an urban soccer player who gets caught in an unexpected rain storm or
an elderly nursing home patient left too long on an outdoor patio in the wind or an
intoxicated transient patient who didn’t bundle up well enough before nightfall.
Hypothermia occurs more often in urban settings that rural settings and you’re just as
likely to encounter it in Detroit, Michigan as you are in Missoula, Montana.
There are five ways to transfer heat and for the body to lose heat. They are:
Conduction: Touching cooler objects transfers’ body heat.
Convection: Air blowing across a warm body carries heat away.
Radiation: Heat radiates off the body into the air.
Evaporation: Sweat and moisture drying on the skin carries heat away from the body.
Respiration: Air gathers warmth in the respiratory tract and we exhale it.
Other factors both external and internal can speed the body’s willingness to sacrifice heat.
Water conducts heat away from the body 25 times faster than air. Therefore, a wet patient
can lose heat 25 times faster than a dry patient. Underlying medical conditions can also
affect the body’s compensatory function. Any medical condition that hinders heart
function, metabolic function, vasoconstriction or shivering will affect the patient’s ability
to maintain core warmth.
Being elderly, young, sick, intoxicated, male or high all make you more likely to
succumb to hypothermia.
So now that we know how the body loses heat and what things might accelerate it, let’s
take a walk through a typical plummeting core temperature. The following numbers
represent degrees Fahrenheit.
103.0-96.4 The normal core temperature range. Remember that body heat fluctuates
quite a bit during a typical day. Exercise might raise core temperature from a standard
98.6 to temperatures as high as 103.0. Body temperature may also fall as low as 96.4 at
rest. Temperatures in our limbs tend to stay 1-2 degrees lower than our core.
95.0 Mild hypothermia. Shivering begins.
93.2 Amnesia and minor errors in judgment begin. An individual may become overly
emotional or easily irritated.
91.4 Major motor coordination begins to fade.
90.0 Moderate hypothermia. More significant changes in mentation including
confusion and stupor.
87.8 Shivering stops. Once this vital heat generation mechanism disappears, core
temperature will drop more rapidly.
86.0 Irregular heart rhythms emerge. Atrial fibrillation is the most common hypothermia
arrhythmia.
85.2 Loss of consciousness more likely. Pupils dilate.
82.4 Spontaneous ventricular fibrillation possible.
80. 6 Severe Hypothermia. Inability to move voluntarily.
78.8 Unresponsiveness to pain.
75.2 Significant hypotension sets in. Pulses become difficult to discern.
71.6 Ventricular fibrillation likely.
57.6 Coldest pediatric resuscitation.
56.7 Coldest successful adult resuscitation.
A good rule-of-thumb assessment for the hypothermia patient is to lay your hand on the
patient’s abdomen. Assuming your hand is normal in temperature, if the abdomen feels
cool to the touch, generalized or total body hypothermia is likely.
With your basic assessment and a rough idea of how the body evolves as hypothermia
progresses, you can make a fairly accurate guess at the patient’s core temperature before
you even hit the power button on the thermometer.
Looking at the progression of symptoms above, one of the real challenges of treating
severe hypothermia becomes apparent. As the body metabolically shuts down in an effort
to save itself, many of the symptoms of moderate and severe hypothermia mimic death
and our aggressive interventions can easily do more harm than good.
Guidelines for treating hypothermia
On the surface, treating hypothermia might seem deceptively simple. The treatment of
mild hypothermia often is simple. Bring them in, stop the cooling and rewarm them. But
as we progress into moderate and severe hypothermia, things get more complicated. Here
are 12 guidelines to consider when the patient is more than just a little chilled.
Stay warm.
Hypothermia patients are often found in cold, wet environments. As a responding EMT,
you need to be prepared. You need to be better prepared than they were to work in that
environment or you may find yourself in a similar predicament.
Dress warm. Use layers and be prepared to work in the cold for a longer operational
period than your best case scenario.
Remove the patient from the environment.
Stop the cooling process. In our rush to initiate more advanced warming techniques, we
can sometimes forget about the basics. Remove wet clothing. Water conducts heat 25
times faster than air. That’s why water is so often associated with these events. If the
patient is wet, from any source, to any degree, dry them.
If the patient is found in a cold environment, getting them out of the environment is a
priority. Find a dry, warm place to initiate rewarming and treatment.
Don’t be fooled by your thermometer.
Most standard thermometers and some tympanic thermometers won’t read below 94
degrees Fahrenheit. Do you know the lowest reading your thermometer is capable of
producing? If not, you may vastly overestimate the patient’s temperature.
Assessment findings are a much more reliable indicator of hypothermia severity than an
over-the-counter thermometer. Is the patient still shivering or have they stopped? How
well is the patient mentating? Pay more attention to your patient than your thermometer.
Check the glucose.
Patients who shiver for long periods of time may become hypoglycemic. To help them
assist in their own rewarming process, a course of glucose may be indicated. Check the
blood sugar and consult with your medical control on the best course of glucose
management.
Avoid rough handling
Individuals in moderate to severe hypothermia stages become more susceptible to sudden
ventricular fibrillation. Bouncing, jarring and rough handling may precipitate a deadly
arrhythmia. Once the heart fibrillates, cardiac arrest is difficult to manage.
Also keep in mind that cold and frostbitten skin is very delicate. We should avoid rubbing
or scraping the skin. Straps should be padded and hot packs and other active rewarming
devices should never be laid directly against the skin.
Support the airway as gently as possible.
Moderate to severe hypothermic patients may breathe slow and shallow. We are
accustomed to managing the hypoventilating patient aggressively, but aggressive airway
interventions may not be warranted due to the patients decreased oxygen demands. And
interventions like nasopharyngeal airways and nasal intubation may precipitate lethal
arrhythmias. Use the least aggressive method for airway management appropriate for the
patient’s condition and respiratory status.
If you don’t think they have a pulse, check again really, really hard.
The American Heart Association is currently recommending that a professional
rescuer feel for a pulse on a hypothermic patient for 45 seconds. If you are unable to find
one, feel for it for even longer, auscultate for it and then feel for it again.
Once the patients skin is cold and the peripheral vasculature is constricted it may be
phenomenally hard to feel a pulse. If the patient’s heart is still beating there’s a great
chance that it’s circulating enough blood to accommodate the patients decreased
metabolic demands, and far more effectively than your chest compressions.
Once we begin compressions we can almost guarantee that the beating heart will
transition into v-fib and the possibility of a successful resuscitation becomes highly
unlikely. Some guidelines even recommend forgoing CPR if you are within 3 hours of
definitive care. If you need to do compressions, do them. But make certain you need to
do them first.
Only defibrillate once.
That goes for AED shocks as well. If the first shock doesn’t work, neither will the second
or the seventh. Try defibrillation one time and then put it aside and continue CPR until
the patient can be warmed.
Skip the cardiac meds if the temperature is below 86 degrees.
Medication administration through peripheral IV’s is ineffective in significant
hypothermia. Worse yet, we stand the risk of loading the patients peripheral vasculature
with metabolized meds that won’t become available until the patient is warmed enough
to begin utilizing their peripheral circulation.
If those vasoconstricted veins are loaded with cardiac medications, we increase the risk of
cardiac arrest during rewarming. Some systems may allow for one round of cardiac meds,
others may say stick to the basics until adequate rewarming can be achieved.
Use warm IV fluids when possible.
Many ambulances now have IV warmers in them. If available, infuse the warm IV fluid.
If your ambulance does not have an IV warmer, you may be able to warm IV bags by
placing them on the dashboard and using the heater/defroster as your warmer. But….be
careful, we want warm fluid, not hot fluid. You may want to warm up a couple extra bags
to tuck under the blankets with the patient.
Recognize the potential for renal failure and other warming complications.
There are many complications associated with the rewarming of serious hypothermic
patients. They are dependent on the degree of hypothermia and the length of time the
body remained cold.
Metabolic acids can build up in limbs and cause a generalized metabolic acidosis during
rewarming. Muscles may break down in a process called rhabdomyoloysis and the
circulating cellular byproducts put the patient at risk for renal complications including
kidney failure.
Nobody is authorized to be dead until they are warm and dead.
As the old adage says, “Patients are not dead until they are warm and dead.” What does
that mean to EMS? Nobody should be considered dead until they are adequately warmed.
True hypothermic patients can be difficult to assess and it can be even more difficult to
determine if they even have a pulse. Pull out all of the tricks in your EMS tool bag. Listen
for a heartbeat, don’t feel for one. Measure End Tidal CO2. Handle the patient carefully
to avoid both internal and external damage. And don’t stop unless they are warm and still
insist on being dead.
A few patients have been resuscitated from remarkably cold temperatures and incredible
exposures. The body’s neuroprotective responses to hypothermia allow the body to go for
long periods with little oxygen and the signs of severe hypothermia mimic death.
We can’t be certain that resuscitation is impossible until we’ve warmed the patient and
allowed them a chance for conversion at normal body temperatures. Treatment of
hypothermia patients is a rapidly evolving field.