Thermoregulation

What is the primary function of thermoregulation?

Stable core body temperature

What are the age-related changes that affect thermoregulation?

• Response to cold temperature

  • Dull perception of cold and lack of stimulus to initiate protection

  • Vasoconstrictive threshold is lowered

  • Decreased muscle mass, peripheral pulses, subcutaneous tissue

  • Narrowed and stiffened vessels

• Response to hot temperature

  • Less able to adapt to hot environments

  • Diminished sweating, sense of thirst

• Normal body temperature and febrile response to illness

  • Studies indicate normal core body temperature in older adults begins to decrease between the ages of 40 and 50 years

  • Temperature elevation in pathologic conditions is diminished with older adults

What are the risk factors that affect thermoregulation?

• Conditions that increase the risk of hypothermia

  • Inactivity, malnutrition, endocrine disorders, and neuromuscular conditions

• Conditions that increase the risk of heat-related illness

  • Physiologic alterations that increase heat production or interfere with ability to respond to heat stress

  • Medications

  • Alcohol

• Environmental and socioeconomic influences

  • Geographic areas with extreme temperature variations

  • Insufficient fluid intake

  • Homelessness

  • Living environments

  • Social isolation

  • Cognitive issues

• Behaviors based on lack of knowledge

  • Age-related vulnerability to hypothermia and heat-related illness: inadequate protective measures

  • Lack of knowledge regarding normal temperature for older adults: undetected illness

What are the functional consequences associated with thermoregulation?

• Altered response to cold environments

  • Death due to hypothermia will result from myocardial effects

• Altered response to hot environments

  • Death due to heat stroke will result from respiratory depression

• Altered thermoregulatory response to illness

  • Diminished febrile response to infections

• Altered perception of environmental temperatures

  • Perception of environmental temperatures associated with pathologic conditions

• Psychosocial consequences of altered thermoregulation

What is the nursing assessment of thermoregulation?

• Assessing baseline temperature

  • Record temperature at different times of the day for several days when well

  • Principles of Temperature Assessment

    • Document the person’s baseline body temperature and its diurnal and seasonal variations.

    • Assume that even a small elevation above the baseline temperature can be an indicator of the presence of a pathologic process.

    • Document actual temperature and deviations from the baseline, rather than using such terminology as “afebrile.”

    • Carefully follow all the standard procedures for accurate temperature measurement. Use a thermometer that registers temperatures lower than 95°F (35°C).

    • Consider the influence of temperature-altering medications when evaluating a temperature reading (e.g., medications that mask a fever).

    • Do not assume that an infection will necessarily be accompanied by an elevated temperature.

    • Remember that, in the presence of an infection, a decline in function or change in mental status may be an earlier and more accurate indicator of illness than an alteration in temperature.

    • Do not assume that an older adult will initiate compensatory behaviors or complain of discomfort when exposed to adverse environmental temperatures

• Identifying risk factors for altered thermoregulation

  • Lower body temperature; diminished response to infection

• Assessing for hypothermia: below 95°F (35°C)

• Assessing for heat-related illness

• Assessing the older adult’s febrile response to illness

  • Questions to Assess Risk Factors for Hypothermia or Heat-Related Illness

    • Do you have any particular health problems that occur in hot or cold weather?

    • Are you able to keep your house or room at a comfortable temperature in both summer and winter months?

    • What do you do to cope with hot temperatures in the summer?

    • Do you have any difficulty paying your utility bills?

    • What forms of protection against the cold do you use in the winter months (e.g., electric blanket, supplemental sources of heat)?

    • Have you ever received medical care for exposure to heat or cold?

    • Have you ever fallen and not been able to get up or get help?

  • Observations to Assess Risk Factors for Hypothermia or Heat-Related Illness

    • Does the older person live in a house where the temperature is kept below 70°F (21.1°C) during the winter?

    • Does the person drink alcohol or take temperature-altering medications?

    • Does the person live alone? If so, what is the frequency of outside contacts?

    • Does the person have any pathologic conditions that predispose them to hypothermia (e.g., endocrine, neurologic, or cardiovascular disorders)?

    • Is the person’s fluid and nutritional intake adequate?

    • Does the person have postural hypotension?

    • Is the person immobilized or sedentary? Is the person’s judgment impaired because of dementia, depression, or other psychosocial disorders?

    • Does the person live in a poorly ventilated dwelling without air conditioning?

    • Are atmospheric conditions very hot, humid, or polluted?

    • Does the person engage in active exercise during hot weather?

    • Does the person have any chronic illness that predisposes them to heat-related illness?

    • Is the person at risk for hyponatremia or hypokalemia because of medications or chronic illnesses?

What are the nursing interventions to promote healthy thermoregulation?

• Addressing risk factors: maintain environmental temperature

• Promoting healthy thermoregulation: adequate clothing and environmental considerations

  • Environmental and Personal Protection Considerations for Preventing Hypothermia

    • Maintain a constant room temperature as close to 75°F (23.9°C) as possible, with a minimum temperature of 70°F (21.1°C).

    • Use a reliable, clearly marked thermometer to measure room temperature.

    • Wear close-knit, but not tight, undergarments to prevent heat loss; wear several layers of clothing.

    • Wear a hat and gloves when outdoors; wear a nightcap and socks for sleeping.

    • Wear extra clothing in the early morning when your body metabolism is at its lowest point.

    • Use flannel bedsheets or sheet blankets.

    • Use an electric blanket set on a low temperature.

    • Take advantage of programs that offer assistance with utility bills and home weatherization.

  • Environmental and Personal Protection Action to Prevent Heat-Related Illnesses

    • Maintain room temperatures below 85°F (29.4°C).

    • If your residence is not air-conditioned, use fans to circulate the air and cool the environment.

    • During hot weather, spend time in public air-conditioned settings, such as libraries or shopping malls.

    • Drink extra noncaffeinated, nonalcoholic liquids, even if you don’t feel thirsty.

    • Wear loose-fitting, lightweight, light-colored, cotton clothing.

    • Wear a hat or use an umbrella to protect yourself against sun and heat when you are outside.

    • Avoid outdoor activities during the hottest time of the day (i.e., between 10:00 AM and 2:00 PM); perform them during the cooler hours of the morning or evening.

    • Place an ice pack or cold, wet towels on your body, especially on the head, the groin area, and armpits. Take cool (about 75°F [23.9°C]) baths or showers several times daily during heat waves, but do not use soap every time.

  • Health Promotion Actions for Maintaining Optimal Body Temperature

    • Maintain adequate fluid intake by drinking 8 to 10 glasses of noncaffeinated, nonalcoholic liquid daily.

    • Do not rely on your thirst sensation as an indicator of the need for fluid.

    • Eat small, frequent meals rather than heavy meals.

    • Avoid drinking caffeinated beverages, such as cola and coffee.

    • Avoid drinking alcohol.

    • In cold weather, engage in moderate physical exercise and indoor activities to increase circulation and heat production.

  • Preventive Measures and Additional Approaches

    • Know your normal temperature in the morning and in the evening.

    • Be aware of seasonal variations in your baseline temperature.

    • Obtain pneumonia and influenza immunizations

    • Maintain good nutrition, especially adequate protein

    • Engage in physical activity, but avoid exertion during hot weather, and use protective clothing during cold weather

• Teaching caregivers

What are the risks for hypothermia and heat-related illness?

• Age 75+ years

• Adverse environmental temperatures

• Pathophysiologic alterations

• Socioeconomic conditions related to poor housing

What are the risks for hypothermia?

• Alcohol, especially excessive amounts

• Stroke

• Dementia

• Diabetic ketoacidosis

• Endocrine disorders (e.g., hypothyroidism, hypoadrenalism)

• Malnutrition

• Parkinson disease

• Renal failure

• Medications: opioids, antipsychotics, barbiturates, benzodiazepines, and tricyclic antidepressants

What are the risks for heat-related illness?

• Alcohol and alcohol withdrawal

• Dehydration

• Diabetic ketoacidosis

• Hyperthyroidism

• Excessive exercise or even moderate exercise in hot and humid environments

• Medications: diuretics, cardiovascular agents, and anticholinergic agents (including antihistamines, phenothiazines, tricyclic antidepressants)

What are the physiologic effects of hypothermia?

Body System	Mild Hypothermia	Moderate Hypothermia	Severe Hypothermia
Neurologic	↓ dexterity ↓ muscle control Difficulty in speaking Amnesia Confusion	Nearly unconscious Coma No voluntary movement	No response to pain
Musculoskeletal	Shivering that cannot be controlled	No shivering	No shivering
Skin	Pale Cool Flushed	Pale Cyanotic	Cyanotic
Cardiovascular	Tachycardia	Dysrhythmias Hypotension	Severe hypotension Asystole
Renal	Diuresis	↓ output	No output
Respiratory	Tachypnea	↓ respiratory rate	Pulmonary edema
Vascular	Vasoconstriction
Gastrointestinal	↓ motility ↓ liver function	↓ motility	Ischemic pancreatitis Ileus Gastric ulcers