5) Factors Affecting Body Temperature Flashcards
How are newborns affected by temperature changes?
- Temperature control mechanisms are immature
- Temperature may respond dramatically to environment changes
- Extra care needed to protect from extremes
What precautions are needed for newborn temperature regulation?
- Adequate body coverings
- Avoid exposure to temperature extremes
- Wear cap to prevent heat loss through head (up to 30%)
What is the normal temperature range for newborns?
- Core and peripheral temperature 36.5°C - 37.6°C
- When protected from environmental extremes
Until what age is temperature regulation unstable?
- Until children reach puberty
How does temperature range change with age?
- Gradually drops as individuals approach older adulthood
- Older adults have lower and narrower range
What oral temperature may be normal for older adults in cold weather?
- 35°C is not unusual
What is the average body temperature for older adults?
- Approximately 36°C
Why are older adults sensitive to temperature extremes?
- Deterioration in control mechanisms
- Poor vasomotor control
- Reduced subcutaneous tissue
- Reduced sweat gland activity
- Reduced metabolism
How does muscle activity affect heat production?
- Requires increased blood supply
- Increased breakdown of carbohydrates and fats
- This increased metabolism causes more heat production
What effect does exercise have on body temperature?
- Any form of exercise increases heat production
- And thus raises body temperature
How high can body temperature rise during prolonged strenuous exercise?
- Up to 41°C temporarily
- Example: Long-distance running
How do hormones affect women’s body temperature?
- Women experience greater fluctuations than men
- Due to hormonal variations in progesterone during menstrual cycle
How does low progesterone affect body temperature?
- Body temperature is a few tenths below baseline level
- Lower temperature persists until ovulation
How does ovulation affect body temperature?
- Greater progesterone enters bloodstream
- Raises body temperature to baseline or higher
How can temperature changes be used for women?
- To predict most fertile time to achieve pregnancy
What temperature changes occur during menopause?
- Intense body heat and sweating episodes
- Lasting 30 seconds to 5 minutes
What is a hot flash?
- Skin temperature increases intermittently by up to 4°C
- Caused by instability of vasomotor controls
How much does body temperature normally change in a 24-hour period?
- Changes 0.5°C to 1°C
When is body temperature usually lowest for day-awake, night-sleep cycle?
- Between 0100 and 0400 hours
When does body temperature reach its maximum?
- Around 1800 hours
- Then declines back to early morning levels
How long does it take for temperature patterns to reverse for night shift workers?
- 1 to 3 weeks
Does the circadian temperature rhythm change with age?
- In general, no
How does stress affect body temperature?
- Physical and emotional stress increases body temperature
- Through hormonal and neural stimulation
- These physiological changes increase metabolism
- Which increases heat production
What situation may cause a higher than normal temperature reading?
- Patient feeling anxious about entering a hospital
- Patient feeling anxious about undergoing a procedure
How can a warm room affect body temperature measurement?
- Patient may be unable to regulate by heat-loss mechanisms
- Resulting in elevated body temperature
How can being outside in the cold affect body temperature?
- Body temperature may be low
- Due to extensive radiant and conductive heat loss
- If patient was outside without warm clothing
Who is most affected by environmental temperatures?
- Infants
- Older persons
- Those with spinal cord injuries
- Due to less efficient temperature-regulating mechanisms
What is poikilothermia?
- Body temperature adjusts to environmental temperature
- Seen in people with spinal cord injuries
What affects the hypothalamic set point for body temperature?
- Body temperatures outside the usual range
What can cause changes in body temperature
- Excess heat production
- Excessive heat loss
- Minimal heat production
- Minimal heat loss
- Or a combination
What determines the clinical problems from temperature changes?
- The nature of the temperature change
What is pyrexia or fever?
- Body temperature rises to an abnormal level
- Because heat-loss mechanisms cannot keep up with excess heat production
When is a fever usually not harmful?
- If it stays below 39°C (102.2°F)
- A single temperature reading may not indicate fever
How is a true fever determined?
- Based on several temperature readings at different times
- Compared to the person’s usual values at those times
What causes a true fever?
- Alteration in the hypothalamic set point
- Triggered by pyrogens like bacteria and viruses
How does the body respond during a fever?
- Hypothalamus raises the set point
- Body produces and conserves heat to reach new set point
What happens during the chill phase of a fever?
- Person experiences chills and shivers
- Feels cold even though temperature is rising
What happens in the plateau phase?
- Chills subside
- Person feels warm and dry
What causes the fever to break?
- Hypothalamic set point drops
- Initiating heat loss responses like vasodilation and sweating
How does fever enhance the body’s immune system?
- Temperature elevations up to 38°C enhance immune function
- White blood cell production is stimulated
- Increased temperature reduces iron in blood plasma, suppressing bacterial growth
- Fever stimulates production of interferon to fight viral infections
How can fever patterns help in diagnosis?
- Fever patterns differ depending on the causative pyrogen
- Increase/decrease in pyrogen activity results in fever spikes/declines at different times
- Duration and degree of fever depend on pyrogen strength and individual’s response
- Fever of unknown origin refers to fever with undetermined cause
What physiological changes occur during fever?
- Cellular metabolism and oxygen consumption increase
- Heart and respiratory rates rise to meet increased metabolic needs
- Increased metabolism uses energy, producing additional heat
- Prolonged fever can weaken the person by exhausting energy stores
What are the risks of fever for certain patient populations?
- For patients with cardiac/respiratory problems, fever stress can be great
- Increased metabolism requires additional oxygen; inability to meet demand causes cellular hypoxia
- Myocardial hypoxia can produce angina (chest pain)
- Cerebral hypoxia can produce confusion
What nursing interventions may be required during fever?
- Oxygen therapy may be needed
- Increased respiration and diaphoresis can lead to excessive water loss and fluid volume deficit
- Dehydration is a serious concern for older adults and low-weight children
- Maintaining optimal fluid volume status is an important intervention
What is hyperthermia?
- Elevated body temperature
- Due to inability to promote heat loss or reduce heat production
- Different from fever, which is an upward shift in set point
- Hyperthermia results from overload of thermoregulatory mechanisms
What can impair heat-loss mechanisms and cause hyperthermia?
- Any disease or trauma to the hypothalamus
What is malignant hyperthermia?
- Life-threatening disorder of skeletal muscle
- In people with pharmacogenetic predisposition
- Characterized by muscle contractions and severe hypermetabolic crisis
- Triggered by volatile anesthetics or succinylcholine
How is hypothermia classified based on temperature?
- Mild: 34-36°C
- Moderate: 30-34°C
- Severe: <30°C
What causes heatstroke?
- Prolonged exposure to sun or high environmental temperatures
- Overwhelms body’s heat-loss mechanisms
- Heat also depresses hypothalamic function
Who is at risk for heatstroke?
- Very young and older persons
- Those with cardiovascular disease, hypothyroidism, diabetes, spinal cord injury, alcoholism
- Patients on medications that decrease heat loss ability (phenothiazines, anticholinergics, diuretics, amphetamines, beta-blockers)
- People who exercise or do strenuous physical labor (athletes, construction workers, farmers)
What are the signs and symptoms of heatstroke?
- Confusion, delirium, excess thirst, nausea, muscle cramps
- Visual disturbances, giddiness, incontinence
- Hot, dry skin (most important sign)
- No sweating due to electrolyte loss and hypothalamic malfunction
What vital sign changes occur in heatstroke?
- Body temperature as high as 45°C
- Increased heart rate
- Lowered blood pressure
What can happen if heatstroke progresses without treatment?
- Loss of consciousness
- Permanent neurological damage
What causes heat exhaustion?
- Profuse sweating (diaphoresis)
- Excessive water and electrolyte loss
What symptoms does a patient with heat exhaustion exhibit?
- Signs and symptoms of fluid volume deficit
How is heat exhaustion treated?
- Transport patient to a cooler environment
- Restore fluid and electrolyte balance
What is hypothermia?
- Abnormally low body temperature
- Caused by prolonged exposure to cold overwhelming heat production
- Classified by core temperature measurements
How can hypothermia occur?
- Unintentionally induced (e.g. falling through ice)
- Intentionally induced during certain surgeries to reduce metabolic demand
What symptoms occur as body temperature drops to 35°C in hypothermia?
- Uncontrolled shivering
- Loss of memory
- Depression
- Poor judgment
What happens as body temperature falls below 34.4°C in hypothermia?
- Heart rate, respiratory rate, and blood pressure decrease
- Skin becomes cyanotic
- Can progress to cardiac dysrhythmias, loss of consciousness, unresponsiveness
What is frostbite?
- Occurs with exposure to extremely cold temperatures
- Ice crystals form inside cells, causing circulatory and tissue damage
- Susceptible areas: earlobes, nose, fingers, toes
- Affected area becomes white, waxy, firm, numb
How is frostbite treated?
- Gradual warming measures
- Analgesia
- Protection of injured tissue
