Thermoregulation

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Thermoregulation
Taylor, ch 25
Objectives
 Please refer to page 3 of your Course Description
under “Domain of the Individual.” There you will
find the outcomes listed for Thermoregulation.
These outcomes are:
– Explain the principles and mechanisms of
thermoregulation.
– Describe nursing measures that promote heat loss and
heat conservation.
– List S/S and identify interventions for hypo and
hyperthermia.
Objectives cont’d
 We will be discussing the concept of
thermoregulation—in other words, what it means
and how temperature is regulated in the body.
 We will also discuss hypo and hyperthermia and
measures to control temperature.
 We will not discuss how to take a temperature.
That is covered in the Vital Signs lecture.
Thermoregulation
 How the body regulates heat loss and heat
production.
 Heat loss has to equal heat production in order
for the body temperature to stay constant. They
occur simultaneously.
 Regulation is controlled by mechanisms in the
body, the environment, and behaviors of the
individual.
Temperature Regulation
 Regulated by hypothalamus which has one part
for heat loss, one for conservation.
 Hypothalamus receives info from
thermoreceptors in the skin and body core
 Sends info to cerebral cortex (voluntary), sweat
glands, blood vessels, and skeletal muscles
(shivering)
Heat Loss
 Controlled by anterior hypothalamus
 Can occur 4 ways:
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–
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Radiation (loss from skin surface)
Conduction (direct contact between objects)
Convection (from air currents)
Evaporation (perspiration)
Which Is It?
 Dilation of blood vessels causes heat loss by
which method?
 Jumping in a cool lake on a hot day can cause
heat loss by which method?
 Standing in front of an air conditioner can cause
heat loss by which method?
 Exercising can cause heat loss by which method?
Heat Production
 Controlled by posterior hypothalamus
 Heat production can occur in three ways:
– Increased metabolic rate from exercising, increased
thyroid gland activity, or fever (10% for every degree)
– Shivering (skeletal muscle contraction)
– Nonshivering thermogenesis in newborns from
metabolizing vascular brown tissue
Factors Affecting Temperature
 Age
 Nutritional status
 Exercise
 Drugs, anesthesia
 Hormones
 Alcohol, cigarettes
 Circadian rhythm
(Figure 32-2)
 Hot and cold liquids
 Stress
 Environment
 Illness/disease
Temperature Terms
 Pyrexia, febrile (elevated temperature)
 Afebrile (absence of fever)
 Hyperthermia (heat exhaustion, heat stroke)
 Hypothermia (frostbite)
 Antipyretic (against fever)
 FUO (fever of unknown origin)
Anatomy of a Fever
 Pyrogens cause body temp to rise
 Hypothalamus responds by raising the set point
from 98.6 to a new level.
 Body responds by heat-producing actions like
chills and shivering.
 When new set point is reached, temperature
plateaus and body stops producing heat
 Temp starts dropping d/t immune system,
antipyretics, and/or antibiotics
 Body responds by sweating, flushing to lose heat
Fever Patterns
 Sustained—continuously elevated above normal
with very little fluctuation
 Remittent—continuously elevated above normal
with spikes
 Intermittent—fever spikes with returns to normal
(<24h)
 Relapsing—fever spikes with returns to normal
(>24h)
Fever S/S
 Headache
 Hot, dry skin
 Flushed skin
 “Glassy” eyes
 Thirst
 Malaise
 Delirium
Fever Can Be Good!
 Important body defense
 Enhances immune system
 Stimulates WBC production
 Suppresses bacterial growth
 Stimulates interferon which fights viruses
 However, very high (>102.2) or prolonged fevers
can be dangerous d/t stress on body
When Temperature Goes Awry
 Hypothermia—prolonged exposure to cold
overwhelms body’s ability to produce heat. May
be mild, moderate, or severe and can lead to
frostbite (frozen cells)
 Hyperthermia—prolonged exposure to heat
causes hypothalamus to lose ability to regulate
temp. Can lead to heat exhaustion & heatstroke.
Symptoms of Abnormal Temps
 Hypothermia
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–
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–
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Temps <86 to 96.8
Falling VS
Shivering
Memory loss
Depression
Poor judgment
Cyanosis
Cardiac dysrhythmias
Unconsciousness
 Hyperthermia
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–
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–
–
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–
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Temps up to 113
Low BP, high P
Diaphoresis?
Confusion
Delirium
Excess thirst
Nausea
Muscle cramps
Unconsciousness
Nursing Actions for Hyperthermia
 Maintain optimum fluid volume status (po or IV) 3 L/d
 Administer antipyretics and antibiotics if appropriate
 Cooling blanket or cool wet towels
 Irrigations of stomach or bowel
 Rest
 Light cover
 Oscillating fans
 Dry linens and clothing
 Control environmental temp
Nursing Actions for Hypothermia
 Remove wet clothes
 Wrap in blankets; keep head and neck covered
and warm
 Lie next to warm person under blankets
 Drink hot liquids if conscious
 Avoid alcohol and caffeine
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