Alterations in Body Temperature (Pyrexia) (complete)

Question 1

What is a fever?

Answer 1

• 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

Question 2

What is the normal body temperature?

Answer 2

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

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

Question 3

What are the diurnal variations of body temperatures?

Answer 3

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

Question 4

What is the role of the hypothalamus?

Answer 4

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

Question 5

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

Answer 5

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

Question 6

What is the thermostatic set point

Answer 6

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

Question 7

Hypothalamus and core temperature; effects of extreme temperature

Answer 7

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

Question 8

What is heat production?

Answer 8

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

Question 9

What does shivering do?

Answer 9

leads to increased heat production by increasing metabolic rate

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

Question 10

What are goosebumps and what do they do?

Answer 10

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

Question 11

What does exercise/exertion do to body temperature?

Answer 11

Increases it

Question 12

Causes of heat production

Answer 12

• 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)

Question 13

What are the 5 processes through which heat loss occurs?

Answer 13

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

Question 14

What is radiation heat loss?

Answer 14

• transfer of heat from one place to another

Question 15

What is conduction heat loss?

Answer 15

Requires direct contact
Ex: cool cloth, ice pack

Question 16

What is convection heat loss?

Answer 16

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

Question 17

What is the febrile response?

Answer 17

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

Question 18

What are the stages of fever?

Answer 18

• prodrome
• chill
• defervescence (fever breaks)

Question 19

What occurs in the prodrome stage of fever?

Answer 19

non-specific complaints (aches, pains, etc)

Question 20

What occurs in the chill stage of fever?

Answer 20

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

Question 21

What occurs during the defervescence stage of fever?

Answer 21

• complains of burning up
• diaphoresis
• fever breaks

Question 22

Associated symptoms of a fever

Answer 22

• 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

Question 23

What is heat stroke?

Answer 23

• 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

Question 24

Treatment for heat stroke?

Answer 24

• cool the person
• antipyretics do not work

Question 25

What is malignant hyperthermia?

Answer 25

- 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

Question 26

Treatment for malignant hyperthermia?

Answer 26

Ice, ice baby dantrolene

Question 27

What is done in the management of a fever?

Answer 27

- 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

Question 28

How does tylenol, ibuprofen, ASA lower fever?

Answer 28

- 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

Question 29

What is hypothermia?

Answer 29

- 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

Question 30

What happens when temperature drops less than 87.8F?

Answer 30

- neurologic signs (confusion, stupor, lethargy, etc) - arrhythmias (*J wave*, A-Fib, etc) the lower the temp, more symptoms related to neuro

Question 31

Fever in children

Answer 31

- 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)

Question 32

Older adults and fever

Answer 32

- 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

Question 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?

Answer 33

"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.

Question 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?

Answer 34

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.