No previously
healthy person should die of hypothermia
after he has been rescued
and treatment has been started.
(Cameron C. Bangs, M.D.
The Mountaineers 1986).
A reduction in the number of
preventable hypothermia-related deaths depends on both treatment and
prevention strategies. Better treatment techniques increase the likelihood
of resuscitation once the victim is rescued. This suggests that education,
prevention and treatment are equally important. Both the knowledge and
technology needed to cope with hypothermia exist it is now a matter of
preparedness and application.
A sampling revealed that the
present method of pre-hospital care is to wrapping the cold victim in a
blanket. This merely provides insulation, which works well for warm
people, but has no benefit to a hypothermic patient as pre-hospital care.
If a hypothermic victim is alive
when rescued but dies during recovery, and there is no other significant
trauma or disease, this suggests that death may have resulted from either
inappropriate or ineffective treatment, or no treatment at all.
Modern hypothermia management is
based, to some extent, on unhappy experiences. Vangaard reports the case
of 16 Norwegian fishermen pulled alive from the North Atlantic all 16 died
shortly afterwards, possibly as a result of exercise (moving/walking)
induced core temperature afterdrop. This, and many other experiences, have
slowly improved hypothermia protocols.
All organizations faced with a
probability of treating hypothermia should be prepared to apply the best
care available, and not that which is merely available or assumed
sufficient to prevent death.
Over the past several years Search
and Rescue (SAR) personnel have become increasingly skilled at managing
accidental hypothermia.
The most critical phase of
HYPOTHERMIA MANAGEMENT for SAR personnel during the first 30 minutes
following rescue are (1) keep the patient alive, (2) thermally stabilize
the patient, (3) transport the patient to a site of complete medical care.
An important and often neglected
consideration is the stress experienced by first responders in treating
hypothermia victims under adverse conditions in the field. In some cases,
evacuation of the victim is not possible or advisable, and the victim must
be stabilized on-site. Severe injuries or arduous terrain may delay
transport, as often found in caving and mountaineering accidents,
difficult maneuvers of the stretcher through constricted passages and the
negotiation of pits, up or down, with lengths anywhere between 10 and 200
feet. Such an evacuation has been reported to have taken 24 hours to
complete.
Delay in transporting a patient may
also apply to urban settings in a motor vehicle accident, or building
collapse, due to earthquakes for example. This problem can also be
complicated with trauma.
All body functions are slowed in
hypothermia, including heart rate, breathing rate, metabolism and mental
activity. A victim of hypothermia may display a variety of different signs
and symptoms.
SAR personnel can both observe and
measure the most important of these:
- Pulse (slow to none);
- Breathing (slow to none);
- Mental status (slurred speech,
unresponsiveness to pain or verbal stimulus,
- staggering walk or
unconsciousness);
- Cold skin; and
- Low rectal temperature.
Severely hypothermic patients may
have other problems that are not easily detected by rescuers, but which
may affect the patient's survival. These include:
- Changes in blood chemistry;
- Changes in oxygen and carbon
dioxide content of the blood;
- Irregular heart beats;
- Dehydration;
- Differences in temperature
between deep body tissues and superficial body tissues.
Hospital humidifiers are designed
primarily for the humidification and warming of anesthesia gases at normal
body temperature, but have been adapted by hospitals for inhalation
rewarming. This is because no inhalation rewarming equipment, dedicated
for treatment of hypothermia, existed before the development of the
RES-Q-AIR system. Thermometers are often placed incorrectly (before the
one way flow valve), thus not registering the effect of room air being
drawn in through a "flow through" open face mask, the inhaled
temperature is consequently much lower than measured.
The growing popularity of outdoor
recreation, has resulted in greater demand for an effective on-site method
of treating hypothermia. Other than for mild cases, the most effective and
safest treatment for all levels of hypothermia is the addition of heat to
the body core, rather than via the periphery, to prevent post-rescue
collapse.
The RES-Q-AIR system meets the
needs of all remote hypothermia treatment scenarios. The ease of operation
and convenience of the systems are an attractive and unmatched feature.
These units provide PRIMARY CARE in almost any location under the most
adverse conditions, including caves and crevasses, it is ideal for remote
situations, including small bush hospitals as well as for use during
transport of hypothermia victims, in ambulances, helicopters, and on board
ships. Units in use and applied during rescues involving hypothermia cases
by the Canadian Coast Guard, have saved lives. Use of the RES-Q-AIR in
ambulances in remote regions is promoted by several hypothermia
specialists. Features such as positive pressure ventilation with oxygen
increases the versatility of the system.
Beside this strategic donation of
heat, inhalation rewarming also eliminates respiratory heat loss, which
accounts for 10% to 30% of the body's heat loss. This is particularly
important in rescue situations where the ambient air is cold (cooling of
the core through respiration). This cooling, if not stopped, can lead to
ventricular fibrillation. Thermally stabilizing a patient, with suitable
equipment, is necessary.
As the only non-invasive hospital
treatment suitable for active core rewarming in the field, inhalation
rewarming donates heat directly to the head, neck, and thoracic core (the
critical core) through inhalation of warm, water-saturated air at 44 °C
(107°F). This method also warms the hypothalamus, the temperature
regulation center, the respiratory center, and the cardiac center at the
base of the brain stem. In many cases, this rewarming of the central
nervous system at the brain stem reverses the cold-induced depression of
the respiratory centers, and improves the level of consciousness.
RESCUING THE PATIENT:
Keep the patient in as horizontal a
position as possible. This will help prevent shock and make it easier for
the patient's heart to maintain blood flow to the brain. This position is
particularly important for patients taken from the water. The pressure of
surrounding water on the patient's body acts, in a small way, like
anti-shock trousers. When the patient is taken from the water, this
pressure is removed, and the patient's blood pressure may drastically
fall. If patients cannot be rescued in a horizontal position (e.g. as in a
rescue basket), they must be so placed as quickly as possible once aboard
the vessel or aircraft.
EXAMINING PATIENT:
Remember ABC's (Airway, Breathing,
Circulation); make sure the patient has an open airway, is breathing and
has a pulse. If there is a high probability that the patient is severely
hypothermic, breathing and pulse may be slow, shallow and very hard to
detect. Therefore, take a full minute or more to measure these vital
signs. Hypothermia patients with any measurable pulse or respiration
obviously do not require Cardio-pulmonary Resuscitation (CPR). However if
both pulse and respiration are absent, commence CPR. If the patient is
found face-down in the water, assume a case of cold-water near-drowning.
In this event commence CPR immediately. Note mental status; evaluate the
patient's level of consciousness, size of pupils, ability to respond if
conscious, ability to walk if ambulatory and ability to think clearly.
Where any of these characteristics are abnormal, suspect possible severe
hypothermia.
Examine the patient for other
possible injuries. Look especially for frostbite, soft tissues injuries,
fractures, etc. Remember that when affected by hypothermia, the patient's
ability to feel and respond to pain are depressed. Therefore a very
careful search for these other injuries is necessary.
Check vital signs; measure pulse,
breathing rate, blood pressure and . Core temperature measurements are
essential (e.g. Tympanic). If tympanic temperature cannot be obtained,
take a rectal or oral temperature. These other sites are not as accurate
as the tympanic temperature, but at least you will know the patient is no
colder than the temperature recorded in these sites (both of which are
almost always lower than tympanic temperature). In all temperature
recordings, low reading thermometers (down to 70°F/21°C) are essential.
Are these provided in all your first aid kits?. Ordinary household
thermometers are not good enough, since they go down to only 94°F/34°C.
Glass thermometers are also unsuitable since hypothermic patients can
thrash about, causing possible breakage and consequently, injury.
TREATING LIFE-THREATENING
EMERGENCIES:
Commence CPR, if necessary; mouth
to mouth or mouth to mask breathing during CPR is best because either
provides warm, humidified air to the patient. However, every effort needs
to be made to use equipment which can ventilate the patient with 100%
heated, humidified oxygen.
Avoid Advanced Cardiac Life Support
(ACLS); normal defibrillation and drug treatments are not useful in
treating severe hypothermia, since the cold heart will not respond as
expected. Worse the heart can be damaged by repeated defibrillatory
shocks. If administered, drugs will not be metabolized or cleared normally
by the patient's liver and kidneys. Instead, they will accumulate in the
body and become active as it warms.
Control bleeding in the usual
manner.
Control shock; evaluate the patient
carefully, especially before using anti-shock trousers. Inflation of the
trousers may expose the heart to a sudden rush of cold, acidotic, venous
blood isolated in the legs. Sudden temperature and/or pH changes in the
heart have been suspected of causing cardiac arrest in severely
hypothermic patients. Anti-shock trousers should only be used if the
patient's low blood pressure is due to blood loss or severe fluid
depletion. Moving a hypothermic patient's extremities may also cause cold
peripheral blood to be pumped into the central circulation, affecting
cardiac rhythm. Gentle handling is critical!
Increased flow of cold blood from
the periphery (muscle pumping from removing clothing, or wrapping in
blankets, or from aggressive external rewarming) can cause after-drop,
increasing the depth of hypothermia in critical core tissues, especially
the heart. It is better to cut away clothing!. Stimulating the peripheral
circulation also reduces the blood volume in the body core, causing
rewarming shock, and increases the work load on the heart. The blood
returning from the periphery can also include metabolic waste products
that cause fatal heart arrhythmia. Active external rewarming is generally
safe only for mild hypothermia, because externally applied heat stimulates
the peripheral circulation. The dangers associated with this have been
explained, also comparative clinical studies have indicated that active
external rewarming has a higher mortality rate than active internal
rewarming.
FURTHER MANAGEMENT:
Handle the patient very gently to
avoid cardiac arrest.
INSULATE from further heat loss;
this is one of the primary goals for rescuers in treating severe
hypothermia. Do not expose the patient's skin to cold air, wind or spray,
especially the down-wash created by helicopter rotor blades. If patients
need helicopter transportation, GENTLY wrap them in blankets, sleeping
bags, etc., and also be sure to insulate their heads. Deliver
heated, humidified oxygen or air by mask at a temperature of 107°F/44°C.
This treatment will prevent further respiratory heat loss which is
significant in hypothermia and will help to stabilize heart, lung and
brain temperatures.
Apply external heat (thermo-pads,
hot packs, heating pads, etc.) to the head, neck, trunk and groin, in
conjunction with inhalation therapy, defending the core temperature. These
sources of external heat MUST be insulated from direct contact with the
patient's skin (wrapped, etc.), in order to prevent thermal burns.
Hypothermic skin is very sensitive to heat and is easily burned.
Postpone orally administered
treatment; give nothing by mouth until the patient is considered
sufficiently conscious to both cough and swallow (i.e. fully conscious).
Hot drinks are not effective in warming a severely hypothermic victim.
They may be useful, however, in raising the morale of mildly hypothermic
victims.
Administer WARM intravenous (IV)
fluids: if a blood vessel can be found, despite vaso-constriction,
administer already warmed to body temperature 5% dextrose in water or 5%
dextrose in normal saline. Do not use Ringer's lactate because the
hypothermic liver may not be able to metabolize the lactate normally. Most
hypothermic patients are dehydrated, administer 300-500 cc's of dextrose
in water or saline rapidly, followed by 75-100 cc/hr. DO NOT ADMINISTER
COLD IV FLUIDS. Use an IV warmer or carry a plastic IV bottle inside a
rescuers clothing (preferably next to the skin) to keep the fluids warm.
Transport to a medical facility as
soon as possible.
Hypothermia fatalities are
significantly greater in immersion hypothermia, but the evidence is often
indirect and fatalities are often recorded as drowning.
Hypothermia fatalities are also
associated with sociological problems and old age, alcohol and drug
intoxication being perhaps the most significant contributing factors. Over
50% of hypothermia deaths reviewed in Manitoba, Alberta and British
Columbia are related to alcohol intoxication. Documentation of
pre-hospital, post-rescue deaths is rare. Information on such cases
probably does exist, but is not published.
Most are presumed dead on discovery
(DOD), after prolonged exposure. This is consistent with findings of an
investigation of exposure-related hypothermia fatalities in Washington,
D.C. (MMWR,1982). Only 10% of these were taken to hospital, and no
treatment results are presented. The issue of presumed death is an
interesting one. In the last decade, the dramatic resuscitation of cold
water "drowning" victims has re-defined the limits of life under
these circumstances.
We have not
encountered any discussions, in any type of publication, concerning
treatment of a mass hypothermia incident, such as would be encountered
during military conflicts, natural disasters, earthquakes and maritime
tragedies.
Nevertheless, we would suggest that
these possibilities are real and that the problem needs to be addressed.
Cold exposure was a significant issue in the Falkland Island conflict,
both at sea and on land. Cold injuries were also a major problem during
the Korean war and WW II.
A review of some of the major
anecdotal evidence suggests that mortality rates are generally low during
hospital treatment of hypothermia, particularly for primary hypothermia in
healthy patients. Success in hypothermia treatment is increasing, largely
as a result of better over all management and understanding of hypothermia
physiology.
Active internal rewarming
techniques in a hospital include: gastric, thoracic and peritoneal lavage
(circulation of heated solutions in body cavities); diathermy (use of
ultra sound and microwave); extra corporeal circulation (circulating and
heating of the blood outside the body); and inhalation rewarming
(ventilation of patients with heated, humidified air or oxygen). Heated IV
solutions are also used. Extra corporeal circulation is used for
profoundly hypothermic patients. Rapid core rewarming is possible with
this method. However it is a complex procedure that can be accomplished
only in intensive care facilities. The risk of complications demands that
it is used only when absolutely necessary. Extra corporeal circulation (ECC)
is the treatment of choice for profound hypothermia. The facilities for
this method are found only in major medical centers. Peritoneal lavage is
a less complicated procedure and can be used for treating severe
hypothermia. Rapid rewarming is also characteristic of this method. None
the less, like ECC, it is an invasive method ("surgical") and
can result in complications.
Hayward's 1984 study recorded
cardiac temperature. In that investigation, there was conclusive evidence
that there was no after-drop associated with the inhalation rewarming
method, nor with spontaneous rewarming, but the rewarming rate of the
core, especially the heart, was greatest with the inhalation rewarming
technique. The rate of rewarming was greatest for the hot water bath
therapy however, after-drop of the heart temperature was observed.
The general awareness of
hypothermia is growing. An increased participation in land-based and
water-based recreation over the last 15 years has been accompanied by
hypothermia education. Research programs on immersion hypothermia has been
conducted at the University of Victoria (British Columbia) This group has
been responsible for the development of survival behaviors (HELP and
HUDDLE positions), hypothermia prevention clothing (UVIC Thermo-Float
jacket), prevention technology (Sea Seat) and treatment technology
(RES-Q-AIR). This research has also provided data on predicted survival
times for man in cold water.
Misconceptions of hypothermia still
abound, regardless of the publicity of research results the media still
reports accounts of people dying of hypothermia in less than 5 minutes
after falling into cold water. Research and real life experience indicate
that people survive cold water immersion much longer than popularly
believed. These and other misconceptions are partly based on continued
reference to outdated information and "mind set". Association of
hypothermia with shock resulting from trauma is rarely considered an event
that can happen frequently and even during summer months.
RES-Q-AIR