Alterations in Body Temperature (Pyrexia) (complete) Flashcards

1
Q

What is a fever?

A
  • elevation in body temperature exceeds normal variations in response to a pyrogen
    – pyrogens: bacteria, viruses, MI, malignancies
  • one of the most prominent manifestations of the acute inflammatory response
  • aka hyperpyrexia
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2
Q

What is the normal body temperature?

A

97-99.5 F (36-37.5C)
- varies about 0.5 degrees throughout day

Different in every person, diurnal variations
- is a dynamic process

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3
Q

What are the diurnal variations of body temperatures?

A
  • lowest temperature in the early morning
  • highest temperature in the late afternoon/evening
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4
Q

What is the role of the hypothalamus?

A

Thermoregulatory center in the hypothalamus regulates body temperature (thermostatic set point)
Helps to balance heat production and heat loss

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5
Q

How does the hypothalamus help to balance heat production and heat loss (other body experiences)?

A

To cool body:
- sweat glands excrete sweat
- blood vessels dilate
- heat loss through radiation and conduction
To heat body:
- erector muscles constrict, traps air (goosebumps)
- shivering: increases metabolic rate, increasing temp
- blood vessels constrict: decreases blood flow to conserve heat

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6
Q

What is the thermostatic set point

A

keeps the core temperature at a normal level (either raises or lowers)

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7
Q

Hypothalamus and core temperature; effects of extreme temperature

A

When core temp is greater than 105.8F or less than 93.2F
- the ability to regulate temperature is impaired
- hypothalamus is no longer in control

Can lead to increased risk of denaturalization of brain cells, leading to cell death, and death

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8
Q

What is heat production?

A

Derived from metabolic activity in the muscles and liver
SNS neurotransmitters play a role (epinephrine and norepinephrine)
- released when an increase in body temp is needed
- heat production rather than energy generation
- often feel weak and tired due to the amount of energy being used

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9
Q

What does shivering do?

A

leads to increased heat production by increasing metabolic rate

side note: non-shivering heat production by the liver can increase core temperature

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10
Q

What are goosebumps and what do they do?

A

contraction of the pilomotor muscles of skin reduce the surface area for heat loss
- surface insulation

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11
Q

What does exercise/exertion do to body temperature?

A

Increases it

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12
Q

Causes of heat production

A
  • work/exercise
  • heat stroke (overwhelms body, impairs organs)
  • drug-induced
  • malignant hyperthermia
  • neuroleptic malignant syndrome
  • CNS damage (can’t regulate temp especially if hypothalamus is impacted)
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13
Q

What are the 5 processes through which heat loss occurs?

A
  • radiation (most common)
  • conduction
  • convection
  • evaporation (sweat)
  • respiration (insensible)
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14
Q

What is radiation heat loss?

A
  • transfer of heat from one place to another
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15
Q

What is conduction heat loss?

A

Requires direct contact
Ex: cool cloth, ice pack

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16
Q

What is convection heat loss?

A

Requires fluid flow, such as air or water
Ex. fan

17
Q

What is the febrile response?

A

During fever, thermostatic set point is reset at a higher level
- caused by a cytokine-induced disruption of the set point in the hypothalamus (inflammatory response)
- cytokines –> arachidonic acids –> prostaglandins –> increased set point
- set point rises, existing body temp is sensed as too cool
– heat production will occur until new set point reached
- once pyrogens decreased or antipyretic given: set point will reset downward
– process of heat loss occurs

18
Q

What are the stages of fever?

A
  • prodrome
  • chill
  • defervescence (fever breaks)
19
Q

What occurs in the prodrome stage of fever?

A

non-specific complaints (aches, pains, etc)

20
Q

What occurs in the chill stage of fever?

A
  • shivering, which causes the core temperature to rise
  • complaints of “freezing to death”
  • vasodilation causes red flushed skin once set point has been reached
21
Q

What occurs during the defervescence stage of fever?

A
  • complains of burning up
  • diaphoresis
  • fever breaks
22
Q

Associated symptoms of a fever

A
  • heart rate: should go up but does not have to happen
    – because of SNS kicking in and NE and E
  • myalgias (b/c prostaglandins)
  • fatigue
  • joint pain
  • respirations increase (trying to blow off heat)
  • dehydration:
    – sweating and increase vapor loss through rapid breathing
  • chills come with pyrogens which enter the system
  • headache: from vasodilation of cerebral vessels
  • decreased perfusion causes delirium, confusion, agitation

symptoms come from increased need for metabolic rate increased, increase oxygen and use of body proteins as a resource

23
Q

What is heat stroke?

A
  • type of hyperthermia
  • person so overheated that heat regulating ability of hypothalamus fails
  • leading cause of death in athletes
    – seen with those with no fans or air conditioning
24
Q

Treatment for heat stroke?

A
  • cool the person
  • antipyretics do not work
25
What is malignant hyperthermia?
- is a rare hereditary disorder - related to exposure to anesthetics and muscle relaxants -- need to ask about problems with anesthesia before surgery - causes a rapid increase in intracellular calcium levels -- leads to muscle rigidity, acidosis, CV instability - hypermetabolic state - temperature increases 1-2 degrees within 5 minutes -- can go higher to like 104-105 F Can be fatal
26
Treatment for malignant hyperthermia?
Ice, ice baby dantrolene
27
What is done in the management of a fever?
- determine cause - monitor CBS with differential (WBC) - monitor CMP (electrolytes, kidney function, glucose) - assess VS (HR and RR had increased, BP can go up or down depending on cause of fever) - fix external environment -- if severe: cooling blankets -- be careful with baths because can cause shivering - hydration is crucial - medication -- acetaminophen -- ibuprofen -- ASA -- reset the temperature control point
28
How does tylenol, ibuprofen, ASA lower fever?
- synthesis of prostaglandin E2 depends on cyclooxygenase (pathway for prostaglandins) -- basis for COX is arachidonic acid released from cell membrance -- release is rate-limiting step in synthesis of PGE2 - inhibitors of COX (1 or 2) are potent antipyretics - if process blocked at arachidonic acid level: prostaglandins are not released
29
What is hypothermia?
- profound loss of body heat for a prolonged period - body temperature less than 95F (35C) - prolonged vasoconstriction and shivering become *ineffective* -- lack of blood flow and oxygen: ischemia, frostbite - loss of thermoregulatory ability - considered a medical emergency
30
What happens when temperature drops less than 87.8F?
- neurologic signs (confusion, stupor, lethargy, etc) - arrhythmias (*J wave*, A-Fib, etc) the lower the temp, more symptoms related to neuro
31
Fever in children
- very common - may or may not have symptoms to indicate the cause of fever - can rebound quickly - can have febrile seizures (not on there, but relating this to peds)
32
Older adults and fever
- not unusual for a sick older adult to NOT have a fever or to be very sick with small elevation -- may present with confusion -- change in mental status - *temperature of 99 may be concerning -- change in baseline -- need to evaluate - confusion and other symptoms may indicate illness
33
A 73 y.o. patient asks the​ nurse, "Why is my body temperature only​ 99.2°F, if I have this serious​ infection?" Which is the​ nurse's best​ response?
"Body temperature in an older adult is not a reliable indicator of the seriousness of an​ illness." Rationale: Body temperature may not be a valid indication of serious illness in an older adult. The older adult may have an infection and exhibit only a temperature elevation. Other​ symptoms, such as confusion and​ restlessness, may be present.
34
The ED nurse is assessing a patient who fell into a cold lake. Which assessment finding indicates that the​ Patient's body is attempting to regulate its​ temperature?
cold hands, shivering Rationale: When the skin is​ chilled, the body attempts to regulate temperature by vasoconstriction of blood vessels. This could be why the​ Patient's hands are cold. The body also shivers to increase heat production. The body does not regulate temperature through​ sleep, thirst, or by sweating.