OVERVIEW OF ISSUES
Severe accidental hypothermia (body temperature below 30°C) is
associated with marked depression of cerebral blood flow and oxygen requirement, reduced
cardiac output, and decreased arterial pressure. Victims may appear clinically dead
because of marked depression of brain and cardiovascular function: full resuscitation with
intact neurological recovery is possible, although unusual. {1} Most clinically
significant episodes of hypothermia result from an injury in a cold environment,
submersion in cold water, or a prolonged exposure to low temperatures without adequate
protective clothing. The victims peripheral pulses and respiratory efforts may be
difficult to detect, but lifesaving procedures should not be withheld based on clinical
presentation.
The very young and the very old are most susceptible to
hypothermia. {1-3} ln infants, core body temperature will cool more quickly than in
adults, as infants have a larger body surface relative to total mass than adults, allowing
greater heat loss. Infants also cannot produce as much heat as adults. Older individuals
have a lower metabolic rate than the young; thus, it is more difficult for them to
maintain normal body temperature when ambient temperatures drop below 18°C. Aging also
seems to be accompanied by changes in the ability to detect temperature changes: older
people may not seek shelter early enough to avoid becoming hypothermic.
Submersion in cold water can cool the core body temperature much
more rapidly than exposure to cold air, because thermal conductivity of water is 32 times
greater than that of air. {4} Hypothermia also can occur in relatively warm water
conditions if exposure is long enough and if core temperature loss is increased by
concurrent ingestion of alcohol.
Alcohol ingestion increases the risk of acquiring or aggravating
hypothermia by causing cutaneous vasodilation (which prevents vasoconstriction),
impairment of the shivering mechanism, hypothalamic dysfunction, and a decrease in
awareness of environmental conditions. {5-7} Other medical conditions that may cause
hypothermia include sepsis in the elderly (through central mechanisms), hypothyroidism
(through decreased metabolic rate), hypopituitarism, hypoadrenalism, head injury (central
mechanisms), drug ingestion (especially barbiturates or phenothiazines through their
actions on the central nervous system), and diabetes (especially when hypoglycemia is
present).
Clinical Features
As core body temperature declines, the basal metabolic rate and
oxygen consumption drop gradually but progressively. {3,4} Mild hypothermia (34 to
<36°C) results in shivering, loss of fine motor coordination, lethargy and mild
confusion. {3-4-8 } In moderate (30°C to 34°C) to severe hypothermia (below 30°C), the
pupils may dilate, and cardiovascular activity ceases (Table). Victims who have
experienced near-drowning prior to becoming hypothermic may aspirate water and have
pulmonary damage, resulting in a much more difficult postresuscitative course. Since
laryngospasm without aspiration of water may accompany near-drowning episodes, hypoxia can
occur without significant pulmonary insult from aspirated water.
Thermoregulatory vasoconstriction helps preserve the core
temperature by preventing cooling of blood in extremities that subsequently returns to the
core. However, with a significant drop in core temperature, the unconscious hypothermic
patient may appear clinically dead (without palpable pulse. blood pressure, or
respiration) but may still be successfully resuscitated with little or no neurological
sequelae if proper and aggressive management is instituted. Fully successful clinical
recovery has occurred in a patient with an initial core temperature of 15.2°C caused by
accidental hypothermia. in a hypothermic child submerged under water for 66 minutes, and
in others with accidental hypothermia. {4-9-10} The use of extra-corporeal bypass can be
important in the successful resuscitation of patients suffering from deep accidental
hypothermia, especially if near-drowning is not involved.
Hemodynamically, mild hypothermia (34°C to 35°C) causes an
increase in pulse rate, peripheral vascular resistance, blood pressure, central venous
pressure, and cardiac output. Moderate (30°C to 34°C) and severe hypothermia (below
30°C) can cause bradycardia, arrhythmias (atrial fibrillation is common, but virtually
any atrial, junctional, or ventricular arrhythmias can occur), hypotension, and a fall in
cardiac output. As the temperature drops below 30°C, the risk of ventricular fibrillation
(VF) dramatically increases; as core temperatures drop lower, VF eventually leads to
asystole. The J wave (Osbom wave), which is most prominent in lead V3 or V4, occurs in 80%
of hypothermic patients and increases in size with decreasing body core temperature. {11}
The J wave may also be seen with sepsis and central nervous system lesions. {12}
Oxygenation and acid-base balance also can be altered by
hypothermia, with the initial manifestation of mild hypothermia (34°C or higher) being
hyperventilation.
Table Key findings at different degrees of hypothermia
Temperature (C) Clinical Findings
- {37} Normal oral temperature
- {36} Metabolic rate increased
- {35} Maximum shivering seen/impaired judgment
- {33} Severe clouding of consciousness
- {32} Most shivering ceases and pupils dilate
- {31} Blood pressure may no longer be obtainable
- {28~3O}
- Severe slowing of pulse/respiration
- Increased muscle rigidity
- Loss of consciousness
- Ventricular fibrillation
- {27}
- Loss of deep tendon. skin and capillary reflexes
- Patients appear clinically dead
- Complete cardiac standstill
As documented by low-registering thermometer.
As the core temperature decreases, there is respiratory
depression with subsequent hypoxemia and hypercarbia. {3} A combined respiratory and
metabolic acidosis may occur due to hypoventilation, carbon dioxide retention, reduced
hepatic metabolism of organic acid due to decreased perfusion of the liver, and increased
lactic acid production from impaired perfusion of skeletal muscle and shivering. {3-8}
There is some controversy about whether arterial blood gases should be corrected for
temperature in the hypothermic patient, although rewarming usually can be expected to
correct the metabolic imbalance after the normal circulation is reestablished. {5-3-14}
Metabolic acidosis can be seen in hypothermic patients and may not respond to bicarbonate
treatment. {15}
Hypothermia affects the function of all organ systems.{4} It can
cause the inhibition of release of antidiuretic hormone and decrease oxidative renal
tubular activity, causing diuresis and volume depletion. {16} The hematocrit may be
elevated due to dehydration and splenic contraction, {4} and plasma viscosity has been
found to increase as the core temperature falls below 27°C {4}. Hyperglycemia also may be
seen in hypothermic patients due to decreased insulin release and inhibition of peripheral
utilization of glucose. This condition often will be reversed with rewarming, although the
use of insulin rarely may be necessary in specific cases. {17} Shivering, if prolonged,
may cause hypoglycemia, as glycogen stores may become completely depleted. Hypoglycemia
also may be an initial laboratory finding in patients who have been exposed to
long-lasting physical endurance and exhaustion and often can be noted in alcoholic
patients, who already may have depleted glycogen stores. {18}
The mammalian diving reflex may be invoked in pediatric
submersion victims. Facial cooling triggers apnea and circulatory shunting to the brain
and heart, {15} which may prove protective. This reflex also may occur in adults, although
the clinical significance remains unclear. {19}
General Principles of Treatment
Early recognition of hypothermia is essential to maximize
survival. Prehospital emergency personnel and emergency department health care providers
must maintain a high index of suspicion in any patient with an altered level of
consciousness who may have been subjected to even a modestly cool environment. All
emergency treatment facilities must have a thermometer capable of registering a
temperature of 30°C or less. Emergency health care providers in areas where cold weather
emergencies may be expected also must be equipped with and trained to use low-register
thermometers (tympanic or rectal probes) and appropriate rewarmmg equipment.
Movement Because the cold heart is irritable and susceptible to
serious arrhythmias (such as VF), all patients with a pulse should be moved gently during
transportation or during transfer of the patient from a stretcher to a hospital bed. The
patient ideally should have vital signs, core temperature, and cardiac rhythm monitored
continuously during transportation, and equipment for resuscitation (including a
defibrillator) should be immediately available. Whenever possible, a horizontal position
should be maintained during movement in order to minimize any potential orthostatic blood
pressure drop due to cold-induced cardiovascular reflex impairment.
Laboratory Tests
When possible, routine laboratory evaluation should be
accomplished, including arterial blood gases (ABGs), a complete blood count, prothrombin
time, partial thromboplastin time, glucose, electrolytes, blood urea nitrogen, serum
creatinine, amylase, liver function tests, ECG, chest radiography; and urinalysis. These
tests will allow a baseline to be established and will be most useful in the
postresuscitative period when complications can occur. There is general agreement that
ABGs need not be corrected during the hypothermic phase, as rewarming will correct all
hypothermic-induced alterations. Rewarming remains the primary treatment in severe
hypothermia for any abnormalities detected.
Interventions
It is important to stress that the severely hypothermic heart
(<30°C) is usually unresponsive to cardioactive drugs, pacemaker stimulation, and
defibrillation. {4} Administered medications, including epinephrine.
lidocaine, and procainamide, can accumulate to toxic levels if used repeatedly in the severely
hypothermic victim. Nonessential interventions should be avoided until the core
temperature is increased to above 30°C. However, indicated and necessary procedures (e.g.
CPR, ventilation, treatment of significant wounds and injuries) should never be withheld.
For example, endotracheal intubation of the severely hypothermic patient may be needed to
protect the airway, to correct hypoxemia and hypercarbia, and to deliver warm,
humidified oxygen. Prior ventilation with 100% oxygen may lessen the likelihood of VF
when invasive procedures are attempted. During transportation of intubated patients, the
tubing of the cuff-port may freeze and break off unless taped firmly to the skin.
Prehospital emergency care providers should be aware that drugs
for prehospital use must be prevented from freezing, as this may affect their therapeutic
strength after thawing. Most drugs can be stored safely at 15°C to 30°C, and heated
drug boxes may be needed for prehospital resuscitations in which ambient temperatures fall
in the low range.
Passive rewarming methods, to be used in mildly hypothermic
victims and as an adjunct in moderate-to-severe hypothermia, include heat packs to arms
and groin areas, heating lamps, warmed blankets, and warm-air-heated "sleeping
bag" devices.
Active core rewarming techniques are the primary therapeutic
modality in hypothermic victims in cardiac arrest or unconscious hypothermic patients with
a slow heart rate.
Drugs pertinent for resuscitation also may be needed in reduced
dosages, at less frequent intervals, or both. No specific guidelines exist on what reduced
dose should be tried, but, in general, the lowest known effective dose can be tried
initially if medication is indicated. Likewise, there are no specific recommendations on
changing the interval of medication administration, but doubling the usual recommended
time between doses would be the initial interval recommended. However, medications, in
general, should be avoided in the hypothermic patient in cardiac arrest until the core
temperature is above 30°C. Hypoglycemia, if present, can be treated with IV glucose.
Volume depletion is a common clinical finding in the severely
hypothermic patient, and IV fluids are indicated. The usual parameters for fluid
assessment may be difficult to use in a hypothermic victim, due to large quantities of
fluid in the "third space" and the clinical difficulty of obtaining orthostatic
blood pressures and weight. It should be emphasized that peripheral access may be quite
limited due to vasoconstriction, and a central line may need to be placed upon arrival in
the ED. IV infusion sets, urinary catheters, suction tubes, and endotracheal tubes may
become stiff and break if not prewarmed prior to prehospital use. IV solutions also
should be prevented from freezing. but standard formulations of saline and dextrose
solutions can be used safely after thawing if no visible precipitates are present and the
bags are intact.
IV fluids should be warmed to approximately 43°C prior to
administration in the prehospital setting to prevent further core cooling. Methods to warm
fluids include using standard blood warmers adapted for saline bag use or portable
battery, operated IV line warmers, preheating saline IV bags and storing them in heated
carrying packs, and micro waving liter bags of saline with insulation during
administration. The use of an insulation barrier around all IV tubing and solutions can
help prevent heat loss from warmed solutions in cold environments.
Prehospital Management The dilemma of a normothermic cardiac
arrest in a cold environment (e.g. a middle-aged man who has a normothermic cardiac arrest
while shoveling snow and subsequently becomes hypothermic) may present a confusing
clinical picture. Basic life support and advanced cardiac life support (ACLS) should be
instituted as soon as feasible, and the appropriate normothermic ACLS algorithm should be
followed. Rewarming techniques may be added to assist in the resuscitative effort. The
Figure presents a recommended hypothermia treatment algorithm. This algorithm presents
the recommended actions that providers should take for all possible victims of
hypothermia. Once hypothermia is suspected, every effort should be made to prevent further
core temperature loss by insulation and by removing wet garments and to cautiously
transport the patient to an appropriate treatment facility.
Increasing body temperature by aggressive external rewarming
techniques before CPR is under way will only increase the metabolic demands of the body
without any accompanying increase in blood supply, thus increasing the chances of
infarction or gangrene. Wet garments should be removed carefully and replaced with dry
(preferably warm) garments. {4-20} Blankets and/or an insulated sleeping bag may be used
to retain body heat, and efforts should be made to shield the victim from wind chill. Cold
sleeping bags should be prewarmed with a volunteer prior to placing a victim inside to
prevent core temperature heat loss. Prehospital personnel may lie (stripped to their
underwear) alongside a conscious victim underneath the covers to assist in
rewarming. Airway
treatments with portable units that can deliver warm, humidified air/oxygen heated to
42-46°C can be used to donate heat back to the core and improve the patient's heat
balance. {21} Exercise is not recommended as a rewarming strategy (unless core
temperature is above 35°C) to prevent fatal arrhythmias secondary to peripheral
vasodilation leading to a decline in blood pressure as well as causing cool blood to
return to the central circulation. {22} Afterdrop, a drop in core temperature after
resuscitation efforts have begun, may occur through significant heat conduction from the
core of the body to more peripheral layers which have not been rewarmed. {23}
ECG monitoring should be performed in the prehospital setting
whenever possible during resuscitation and transport. Prehospital personnel also should be
aware that adhesive pads for monitor leads will not stick to cold skin, and conduction of
electrical signals across cold skin may be impaired in such settings. In patients with
moderate-to-severe hypothermia in whom such conduction of ECG signals is affected, needle
electrodes may need to be inserted. The needle may be an injection needle punctured
through the gel-foam of a conventional adhesive pad which is then. in turn, connected to
the ECG electrode of the monitor. This method avoids the need to have specially-made
needle electrodes for each machine. In cold environments in which continuous monitoring is
desired, tincture of benzoin may be needed to maintain contact of the monitor leads. The
QRS amplitude should be maximally amplified if no complexes are seen initially.
Most electrical medical devices to be used in the prehospital
setting (defibrillators and monitors) have recommended operating temperatures above
15.5°C, and circuit breakers on generators and power distribution boards should be
checked often to prevent freezing. Any required monitoring equipment for prehospital use
should be properly insulated prior to utilization. Batteries are affected by very low
temperatures, which may affect performance of equipment.
Mild Hypothermia (34°C to 35°C)
Patients with mild hypothermia(34°C or above) generally have a
good prognosis regardless of the rewarming method used. {4-8} In the conscious patient,
external rewarming is appropriate, either passively by using blankets or actively using
hot water bottles, warm baths, or chemical heat packs placed under the arms and on the
neck, chest, and groin. These methods can allow the patient to warm at a rate of 0.5°C to
1°C per hour. Although quite effective, warm baths have the disadvantage of not allowing
the cardiac rhythm to be monitored. Rough movements should be avoided, as discussed above.
Wet clothing should be removed carefully, and the patient should be insulated and
protected from wind chill. The patient should be cautioned not to exercise as a method of
rewarming because of the potential for cardiovascular collapse. Prognosis usually is quite
good.
Moderate Hypothermia (30°C to 33.9°C)
Prehospital treatment
of moderate hypothermia should include all the basic measures listed above except external
rewarming. CPR should be initiated promptly if the patient is in cardiac arrest,
although pulse and ventilations may need to be checked for longer periods of time to
detect minimal cardiopulmonary efforts. The recommendation that pulse and ventilations be
checked for one to two full minutes prior to initiating CPR {24-25} is probably excessive.
A maximum of 45 seconds should be adequate time to confirm pulselessness or profound
bradycardia for which CPR would be required. Loss of pupil reflexes,
hyporeflexia,
absent blood pressure, and lack of response to painful stimuli may not indicate clinical
death in the hypothermic patient. A routine search for external trauma should be
accomplished by prehospital personnel, and treatment should be initiated (e.g., pressure
dressings, etc.). Obvious physical evidence of death would mitigate against beginning
resuscitation (e.g., gross evisceration, decomposition, decapitation). Stiffness of the
victim's body, which can be caused by hypothermia, should not be confused with classic
rigor mortis.
Rewarming is not the mirror image of the cooling process,
especially for patients who have developed moderate-to-severe hypothermia over a prolonged
period of time. Attempts at rewarming such patients by application of external heat (such
as heat lamps, electric blankets, chemical heat packs, etc.) are hazardous, because such
interventions will cause sudden peripheral vasodilation and allow cold, lactic acid-rich
blood to return to the core and cause a convective afterdrop in core temperature and pH,
{21-23} increasing the likelihood of VE. {4}
Minimizing convective afterdrop by preventing return of cool.
peripheral blood and by donating heat to the core during initial management is a key goal.
This is accomplished by passive rewarming and stabilization methods (covering with
blankets, blocking exposure to wind, and removing wet garments). Most afterdrops occur
during the first few minutes of treatment, and rewarming efforts in this group of
hypothermic victims should be directed to the core (warm humidified oxygen or air; warmed
IV fluids).
In the hospital setting, patients who are conscious and have an
effective circulation also may be treated with external rewarming to truncal areas only,
but constant monitoring must be maintained to detect any potential afterdrop that can
occur.
Severe Hypothermia (<30°C)
Although the ability to treat severely hypothermic victims in the
prehospital setting will vary depending on the equipment available to prehospital
personnel, most resuscitative efforts should be directed to performing CPR in cardiac
arrest victims and transporting them to a hospital setting where definitive rewarming can
take place. Treatment of severe hypothermia in the out-of-hospital setting remains
controversial. Many providers do not have the equipment or time to adequately assess
core body temperature or to institute rewarming with warm, humidified oxygen or warm
fluids, although these methods should be initiated if possible to help prevent
afterdrop.
Cardiac monitoring and IV access should be established rapidly if
possible. but should not delay transport. Recently developed portable techniques allow
the administration of warm, humidified air or oxygen (heated to 42 - 46°C) and heated lV
solutions, {5} although these are not in widespread use at present. Core temperature
determinations in the prehospital setting with either tympanic membrane sensors or rectal
probes are recommended, but they also should not delay transfer. Airway management and
transportation should be undertaken as gently as possible in order to avoid precipitating
VF, and the patient should be moved in the horizontal position to avoid aggravating
hypotension through orthostatic mechanisms.
Endotracheal intubation to provide effective ventilation with
warm, humidified oxygen and to prevent aspiration should be performed in the unconscious
hypothermic patient with inadequate ventilation. In such cases, prior ventilation with
100% oxygen through a bag-valve mask is recommended. In a prospective multicenter study of
hypothermia victims, careful endotracheal intubation did not result in a single incident
of VF. {26}
If the hypothermic victim is in cardiac arrest, follow the
hypothermic treatment algorithm (Figure). If VF is detected, emergency personnel
should deliver three shocks to determine fibrillation responsiveness (including the use of
automated external defibrillators). If VF persists after three shocks, further shocks
should be avoided until after rewarming to above 30°C. CPR, rewarming, and rapid
transport should immediately follow the initial three defibrillation's. If core
temperature is below 30°C, successful defibrillation may not be possible until rewarming
is accomplished. {4}
Hospital Management
Treatment of severely hypothermic victims in cardiac arrest in
the hospital setting should be directed at rapid core rewarming. Additionally, trauma
should be sought and treated in hypothermic victims, as injured patients with core
temperatures less than 32°C are likelier to die than those with normal temperatures. {27}
Although esophageal temperature is a good indicator of heart
temperature, {25} most EDs use tympanic membrane or rectal temperatures. However it should
be noted that using tympanic devices in patients with cerumen-blocked external canals or
placing rectal probes in frozen feces will not be effective due to the inability to obtain
an accurate reading. {5}
Techniques that can be used for rapid core rewarming include
the administration of heated, humidified oxygen (42°C to 46°C). warmed (43°C) IV fluids
(normal saline) infused centrally at rates of approximately 150 to 200 ml/hr (note:
avoid overhydration), peritoneal dialysis with warmed (43°C) potassium-free dialysate
administered two liters at a time (no dwell time), and/or extra-corporeal blood warming
with partial bypass. {4-5-20-25} A complication of overvigorous hydration is pulmonary
edema, which can be treated with standard medications after an effective circulation is
restored. Extra-corporeal rewarming should be utilized, if available, in the severely
hypothermic patient, as this will allow the most rapid and controlled core
rewarming. {9}
The use of esophageal rewarming tubes has not been reported in the United States, although
they have been utilized extensively in Europe in hospitals without extra-corporeal
rewarming equipment. {28} Pleural lavage with warm saline instilled through a chest tube
also has been used successfully {26-29} to increase core temperature as much as 2.5°C per
hour but has the major disadvantages of possible infection, bleeding, and the requirement
for large volumes of fluid. The routine administration of steroids, barbiturates, or
antibiotics has not been documented to be of any help in increasing survival or decreasing
postresuscitative damage. {30} Additionally; the use of lactated Ringer's solution may be
dangerous due to reduced hepatic metabolism of lactate in the hypothermic state. {25}
Bradycardia may be physiologic in severe hypothermia, and cardiac
pacing is usually not indicated unless bradycardia persists after rewarming. The
temperature at which defibrillation first should be attempted and how often it should be
tried in the severely hypothermic patient have not been established firmly. There are also
conflicting reports about the efficacy of bretylium tosylate in this setting, {31-32}
although it may prove helpful in VF by decreasing the defibrillation threshold.
Recently arterial and venous catheters have been utilized to
create a circulatory fistula through which the blood is heated by a modified commercially
available countercurrent fluid warmer, thus achieving a more simplified extracorporeal
rewarming method. {33} Heparin-free systems are now becoming available {34} which may
prevent aggravation of coagulopathies seen in hypothermic patients. Radio frequency
rewarming is still being developed as a method of rapid core rewarming. {35}
Continuous core temperature and cardiac monitoring should be
performed, as well as placing a urinary catheter to monitor urine output. Pulse oximeters
do not work well in vasoconstricted hypothermic patients and will not accurately reflect
oxygenation. {5}
Postresuscitative complications may include pneumonia, pulmonary
edema. atrial arrhythmias, acute tubular necrosis, acute pancreatitis, compartment
syndromes, disseminated intravascular coagulation, hypophosphatemia,
hemolysis,
intravascular thrombosis, myoglobinuria, seizures, and temporary, adrenal insufficiency.
{4-5-36}
Severe accidental hypothermia is a serious and preventable health
problem. Clinicians should look for ''urban" hypothermia in inner city areas,
where it has a high association with poverty and drug and alcohol use. {37-38} In rural
areas, over 90% of hypothermic deaths are associated with elevated blood alcohol levels.
{39}
Terminating Resuscitative Efforts
Some clinicians believe that patients who appear dead after
prolonged exposure to cold temperatures should not be considered dead until core
temperatures are near normal and CPR still elicits no response. If drowning preceded the
victim's hypothermia, successful resuscitation may be unlikely. Hypothermic victims should
be treated aggressively, because even when all vital signs are absent, survival without
neurological impairment may be possible in certain patients. Although some investigators
have suggested elevated potassium as a marker for poor outcome, {40} no specific chemical
indicator can predict with complete accuracy who will recover. The old clinical maxim that
no one is presumed dead until they have been rewarmed to near normal temperatures can not
be applied literally in all cases. Rewarming efforts, in general, probably should be
continued until core temperature is at least 32°C and may be discontinued if the patient
continues to show no effective cardiac rhythm and remains totally unresponsive to all
treatment. However, the decision to terminate resuscitation must be individualized by the
physician in charge and should be based on the unique circumstances of each incident.
Successful treatment of hypothermia requires optimal training of
emergency personnel and appropriate ACLS resuscitation methods at each institution.
Because severe hypothermia is frequently preceded by other disorders (e.g., drug overdose,
alcohol use, trauma, etc.), the clinician must seek and treat these underlying conditions
while simultaneously treating the hypothermia.
COMMENTARY
The introduction of a new algorithm for the treatment of
hypothermia will facilitate the teaching of basic assessment and rewarming techniques to
all health care providers. For hypothermic victims in the prehospital setting, the use
of CPR, removing wet clothing and sheltering from wind chill, and stabilization with
warmed air/oxygen and IV fluids constitute the initial treatment modalities.
In-hospital rewarming and management can require intubation, central line placement,
warmed peritoneal dialysate lavage, and extracorporeal treatment. Close postresuscitative
management will require close in-hospital observation for a variety of potential
pulmonary, hematologic. and renal complications.
RESEARCH INITIATIVES
Additional research on the use of bretylium and other
antiarrhythmic medications in hypothermic VF clearly is indicated, as well as research on
dosing and interval reductions required when administering medications in hypothermic
victims. Evaluation of the ideal temperature to first attempt defibrillation in patients
with hypothermic VF also needs to be conducted. Further research on microwave rewarming of
hypothermic patients and other prehospital rewarming techniques needs expansion.
Hypothermia
treatment algorithm - full size(1038x1706)
(a) May require needle electrodes through the
shin.
(b) Many experts think this should be done only in-hospital.
(c) Methods include electric or charcoal warming devices, hot water
bottles, heating pads, radiant heat sources, and warming beds.
(d) Esophageal rewarming tubes are widely used in Europe.
Abbreviations:
VF = ventricular fibrillation
VT = ventricular tachycardia
J= joules
KCL = potassium chloride
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The author greatly acknowledges the advice and contribution of
Drs Roger D White, Richard 0 Cummins, Svein Hapnes, Mads Gilbert, Kristian
Lexow. and
James L Paturas, EMT-P, in the development of this material.
Address for reprints:
Andrew D Weinberg. MD
1647 Brookhaven Close, NE
Atlanta, GA 30319
RES-Q-AIR