Hypothermia |
Race:
Sex:
Age:
CLINICAL
History: In some cases, hypothermia is suggested by an obvious history, such as a skier who is caught in an avalanche. In other cases, the history may not suggest the diagnosis of hypothermia, for example in an elderly person who comes into the emergency department in cardiac arrest. The signs and symptoms of hypothermia vary according to core temperature and represent a continuum rather than definitive categories. Especially in urban settings, the presentation may be subtle and easily overlooked.
Because hypothermia may accompany a more obvious condition, keeping hypothermia in the differential diagnosis as a comorbidity in any patient, especially elderly patients, who present with unexplained symptoms is critical. Also important is remembering that the symptoms of the primary condition may overshadow the symptoms of hypothermia.
Physical: Physical findings vary with the degree of hypothermia and with the nature of associated injuries or illness. The underlying illness, such as a stroke, may obscure the physical signs of hypothermia. Using a thermometer capable of registering as low as 25°C (77°F) for measuring core temperature is important. Note that the symptoms represent a continuum, and a fair amount of variability exists from patient to patient. Determination of body temperature from the clinical examination, with the exception of a core temperature reading, is not possible
Causes: Humans have developed considerable behavioral adaptations to cold weather. Any disease that interferes with this adaptive behavior places a patient at risk. Because hypothermia itself alters mental status, patients with mild hypothermia may experience a downward viscous cycle of continued heat loss and maladaptive behavorial patterns. Hypothermia is more frequent among persons who are elderly, homeless, mentally ill, trauma victims, outdoor workers, and children.
DIFFERENTIALS
Alcoholism
Anorexia Nervosa
Delirium
Frostbite
Hypopituitarism
(Panhypopituitarism)
Hypothyroidism
Myocardial Infarction
Pneumonia,
Bacterial
Sepsis,
Bacterial
Septic
Shock
Shock,
Hemorrhagic
Other Problems to be Considered:
Any disease can precipitate hypothermia if the heat-generation/heat-loss
balance moves towards heat loss. The list of possible causes is immense. Some of
the more common causes include the following:
Imaging Studies:
Other Tests:
Procedures:
TREATMENT
Medical Care: Treatment begins in the prehospital environment, with removal of wet clothing, passive rewarming of the victim, and removal from the cold environment. Associated injuries are stabilized, and the patient should be transported as soon as possible. Rough handling of the patient may precipitate ventricular arrhythmias and should be avoided. An axiom in treatment is that a patient with hypothermia may appear dead; therefore, a patient is not considered dead until they are warm and dead.
Consultations:
MEDICATION
The goals of
pharmacotherapy are to reduce morbidity and prevent complications.
Drug Name |
Bretylium tosylate (Bretylium) -- Until it became unavailable, was the DOC for hypothermia-induced ventricular fibrillation. Class III antiarrhythmic agent that lengthens ventricular action potential duration and effective refractory period, increasing the strength needed to induce ventricular fibrillation. Causes an initial catecholamine release and therefore has some positive inotropic properties. Has a half-life of approximately 4 h. |
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Adult Dose | Initial dose: 5 mg/kg over 10 min; may be repeated in 30 min |
Pediatric Dose | Not established |
Contraindications | Documented hypersensitivity; systemic lupus erythematosus, digitalis-induced arrhythmias, complete heart block or second-degree or third-degree heart block if a pacemaker is not in place; avoid in torsade de pointes |
Interactions | Pressor catecholamines and digitalis may increase toxicity; coadministration with ofloxacin may increase risk of cardiotoxicity |
Pregnancy | C - Safety for use during pregnancy has not been established. |
Precautions | May cause hypotension, especially in patients with fixed cardiac output (eg, aortic stenosis); caution in renal insufficiency, severe pulmonary hypertension, and aortic stenosis; half-life increases in elderly; with renal clearance of 10-50 mL/min, administer 25-50% of the dose; rapid IV injections may result in transient hypertension, nausea, and vomiting; limit injection to 5 mL (undiluted) at each injection site |
Drug Name |
Amiodarone (Cordarone) -- Use of this
drug in hypothermia is not supported by research. May inhibit AV conduction and sinus node function. Prolongs action potential and refractory period in myocardium and inhibits adrenergic stimulation. Prior to administration, control the ventricular rate and CHF (if present) with digoxin or calcium channel blockers. |
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Adult Dose | Loading dose: 800-1600 mg/d PO in 1-2
doses for 1-3 wk; decrease to 600-800 mg/d in 1-2 doses for 1
mo Maintenance dose: 400 mg/d PO; alternatively, 150 mg (10 mL) IV over first 10 min, followed by 360 mg (200 mL) over next 6 h, and then 540 mg over next 18 h |
Pediatric Dose | 10-15 mg/kg/d or 600-800 mg/1.73 m2/d PO for 4-14 d or until adequate control of arrhythmia is attained |
Contraindications | Documented hypersensitivity, complete AV block, and intraventricular conduction defects; patients taking ritonavir or sparfloxacin |
Interactions | Increases effect and blood levels of theophylline, quinidine, procainamide, phenytoin, methotrexate, flecainide, digoxin, cyclosporine, beta-blockers, and anticoagulants; cardiotoxicity is increased by ritonavir, sparfloxacin, and disopyramide; coadministration with calcium channel blockers may cause an additive effect and further decrease myocardial contractility; cimetidine may increase levels |
Pregnancy | C - Safety for use during pregnancy has not been established. |
Precautions | Caution in thyroid or liver disease |
Patient Education:
MISCELLANEOUS
Medical/Legal Pitfalls:
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Constructed by Dr N.A. Nematallah Consultant in perioperative medicine and intensive therapy, Al Razi Orthopedic Hospital , State of Kuwait, email : razianesth@freeservers.com