Hypothermia

Hypothermia is ...

Defined as a decrease in core body temperature below 95°F caused by deliberate or accidental conditions (Ham & Sloane, 1997).

Classification is based on 3 factors ... pathophysiology, the rate of heat loss, and the severity of decrease in body temperature.

 

PRIMARY HYPOTHERMIA: Resident has normal thermoregulation, but is subjected to an overwhelmingly cold stressor.

 

SECONDARY HYPOTHERMIA: Resident has underlying condition (i.e. cerebrovascular disease, neurological disorder, medication induced, shock, sepsis) that is responsible for the development of hypothermic state with exposure limited to only mild-moderate cold stressor. In elderly (frail and/or over age 75), hypothermia is generally of this type (Centers for Disease Control, 2000; Ham & Sloane, 1997).

 

Or by temperature

Or by onset

MILD: 89.6 - 95°F

GRADUAL: DAYS - WEEKS
Most common in elderly

MODERATE: 82.4 - 9.6°F

SUB-ACUTE: SEVERAL HOURS

SEVERE: 82.4°F and <

ACUTE: ONE HOUR 

Hypothermia is under-reported and under-recognized in the elderly. A severe cold stressor is not necessary to its development. Hypothermia can occur at ambient temperatures in the frail elderly, during any season, anywhere.

 

Predisposing factors in the frail and elderly:

External: Climate, social circumstances, inadequate clothing.

 

Internal: Aging is associated with a decrease in resting peripheral blood flow, shivering, muscle mass, fat stores, and metabolic rate, all of which contribute to a decline in thermoregulation.

 

Chronic predisposing conditions: Diabetes mellitus, dementia, depression, arthritis, cerebrovascular disease, ischemic heart disease, history of falls or CVA, hypothyroidism, under nutrition, use of sedative hypnotics, valproic acid, vasoactive or other drugs, or room temperature < 62.6°F (Ham & Sloane, 1997)

Why are the elderly more susceptible?

 

Vasoconstriction and shivering, which are primary physiological adaptive responses to conserve heat, appear to be decreased in the elderly (Collins, 1984). Thus, maintenance of thermoregulation by responses is blunted, leading to increased susceptibility to hypothermia. Symptoms may be non-specific, confused with other conditions or go unnoticed. Symptoms are easy to explain away. The elderly may not discriminate temperatures well, and lack precision in adjusting their thermal environment (Collins, 1981). With core temperatures between 95-97°F, most elders will perceive being cold. However, once hypothermia sets in, symptoms of being cold may not be recognized.

Early Signs: Mental confusion, apathy, lethargy, combativeness, slurred speech, poor coordination, impaired or slow gait, bradycardia, hypotension, cold skin, shivering may be absent.

 

Late Symptoms: Hallucinations, persistent purple fingers, toes, and nail beds, edema of the skin, dilation of the pupils, stupor, decreased respiratory rate, weak or irregular pulse, muscle tensing, a feeling of deep cold or numbness, intense shivering (Centers for Disease Control, 2000).

 

Diagnosis: Have a low reading thermometer available to determine rectal core temperature. A low reading thermometer is capable of measuring temperatures from 77°F to 104°F. Hypothermia is a medical emergency. Notify the health care provider (Ham & Sloane, 1997; Collins, 1984).

 

Treatment: Successful treatment includes rapid assessment, appropriate supportive therapy, resuscitative measures if necessary and rewarming. Goals are to maintain or restore adequate cardiopulmonary function, fluid and electrolyte status, minimize additional heat loss, obtain a normal core body temperature within 4 hours, eliminate environmental precipitating causes, and treat coexisting conditions (Briggs, 1997; Ham & Sloane 1997) .

 

Rewarming: Passive external rewarming consists of relocating the resident to a warm environment (at least 70°F), and insulating from additional heat loss. Remove any wet clothing and replace with dry clothing or warm blankets. Mild hypothermia usually presents with stable cardiopulmonary status, and responds adequately to passive rewarming.

In addition, encourage the resident to drink warm fluids if alert and oriented. Provide high-energy food (fruit, carbohydrate, candy).

 

Active external rewarming uses heat sources such as water bottles and electric blankets to transfer heat. Be alert to signs of afterdrop (reduction of core temperature by cold blood circulating from the periphery) and aftershock (hypotension caused by peripheral vasodilation).

 

Active core rewarming for moderate to severe hypothermia includes internal and invasive measures such as intravenous warmed crystalloids, gastric irrigation, warmed and humidified oxygen, peritoneal dialysis and extracorporeal blood rewarming. IV fluids and O2 may be initiated in the long-term care facility upon provider order, prior to transfer.

Goals: The reduction of risk factors is achieved through education of staff, residents and family as to etiology, signs, symptoms and significance of hypothermia. The natural production of body heat from metabolic processes can also be enhanced through adequate nutrition.

Inservices may be also be offered on signs and symptoms of frostbite after exposure. First-degree frostbite is reflected in a frozen, numb area without blistering. Second-degree frostbite includes a frozen area with blistering or peeling skin. Blisters develop with rewarming. Signs of infection may subsequently develop (increased redness, swelling, pain, drainage, pink streaks, increased warmth and fever). Third-degree frostbite includes hard, cold, white or blue-blotchy skin. Symptoms of hypothermia may be present in all 3 stages. Care must be taken to soak the cold part in warm water only (101 - 108°F), or apply a warm compress for 10-30 minutes. Thawing and return to normal temperature will occur over 1 -1 ½ hours (Briggs, 1997).

 

Prevention of situations leading to hypothermia should include additions to the resident's care plan: extra clothing (sweater, hat, lap robe, warm socks) may be worn when in drafty or open areas, warm beverages may be offered, and frequent communication and assessment documented. Frail elderly are dependent on caregivers to promptly recognize, intervene and correct hypothermia.

 

Wandering residents present a greater risk for hypothermia during the winter months, due to the potential for elopement. Facilities need to take extra measures to prevent wandering, and assess for signs/symptoms of hypothermia if a resident does elope in cold weather. A review of policies, alarms, procedures and preventative measures with current staff will assist them in acting quickly should elopement occur.

We hope this provides you with an informative overview on hypothermia!

 

References:

Briggs, J.K. Telephone Triage Protocols for Nurses. Philadelphia: Lippincott, 1997

 

Centers for Disease Control. Perspectives in Disease Prevention and Health Promotion: Hypothermia - Associated Deaths- United States. MMRW 1985;34(50):753-4

 

Collins, K.J. Hypothermia: the facts. New York: Oxford University Press, 1983

 

Collins, K.J., Dore, C., & Exton-Smith, N.A. Shivering Thermogenesis and vasomotor responses with convective cooling in the elderly. Journal of Physiology 1981;320:76

 

Collins, K.J., Exton-Smith, N.A. & Dore, C. Urban hypothermia: preferred temperature and thermal perception in old age. British Medical Journal 1981;282:175-7

 

Ham, R.J. & Sloane, P.D. Primary Care Geriatrics. St. Louis: Mosby, 1997