Module 7 - Thermoregulation

Question 1

Definition of thermoregulation

Answer 1

process of maintaining a steady internal body temp

Question 2

Hypothermic range

Answer 2

<36

Question 3

Fever range

Answer 3

> 37.5-37.8

Question 4

Hyperpyrexia

Answer 4

> 41.5

Question 5

Which brain structure regulates body temp

Answer 5

Hypothalamus

Question 6

Sources of heat gain/conservation

Answer 6

external sources (blankets, clothing)
increased cellular metabolism (BMR)
ingestion of food (liver)
muscle activity (contractions)
vasoconstriction

Question 7

Sources of heat loss

Answer 7

vasodilation
sweat evaporation (greatest heat loss)
breathing
insensible water loss (thru skin)

Question 8

Aging & thermoregulation

Answer 8

lower core body temp (d/t slower metabolism & less muscle mass)
reduced ability to generate fever
loss of subq tissue

Question 9

Stress & thermoregulation

Answer 9

stress increases heat by;
increasing cellular metabolism (increases heat)
superficial vasoconstriction –> blood shunted to core (reduced heat loss)

Question 10

Fever

Answer 10

increase in body temp d/t resetting of the hypothalamic thermostat

Question 11

Pyrogenic cytokines

Answer 11

IL-1
IL-6
TNF
interferon a

Question 12

Hyeprthermia

Answer 12

increase in body temp that does not involve hypothalamic resetting
caused when heat gain exceeds heat loss

Question 13

Types of pyrogens

Answer 13

endogenous (inflammatory cytokines)

exogenous (bacterial toxins)

Question 14

What type of bacteria releases endotoxins

Answer 14

gram negative bacteria

Question 15

Conditions causing fever

Answer 15

infection

inflammation

Question 16

S/S of systemic inflammation

Answer 16

fever
increased WBC count
elevated CRP/ESR
malaise, anorexia, fatigue

Question 17

PGE2 in the CNS

Answer 17

acts on the hypothalamus to reset the thermoregulatory center –> fever

Question 18

PGE2 in the PNS

Answer 18

acts on peripheral tissue –> causes arthralgia/myalgia assoc with fever

Question 19

Conditions causing hyperthermia

Answer 19

malignant hyperthermia

PSR

Question 20

Conditions cuasing hypothermia

Answer 20

heat loss during surgery (open body cavity, fx of anesthesia, OR temp, blood loss)
therapeutic hypothermia

Question 21

Pyrogen definition

Answer 21

fever causing substances

Question 22

Direct mechanism of fever

Answer 22

endogenous pyrogens (cytokines) enter the systemic circulation –> travel to the brain –> stimulate release of PGE2 by endothelial cells loc close to hypothalamus

Question 23

Stages of a fever

Answer 23

chill
fever
defervescence

Question 24

Chill phase

Answer 24

discrepancy b/w new set point & body temp –> triggers bodily response to increase body temp
ex: shivering, vasoconstriction, increased metabolism, PSR, drinking warm fluids, increasing environmental heat

Question 25

Defervescnece phase

Answer 25

pyrogens stop acting on hypothalamus --> thermostat returns to normal body responds by increasing heat loss ex: vasodilation, sweating, removing layers, external cooling mechanisms, rest (reduce metabolism)

Question 26

Causes of infectious fever

Answer 26

``` SSI UTI pneumonia sepsis abscess catheter-assoc infections C. diff peritonitis ```

Question 27

Causes of non-infectious fever

Answer 27

``` inflammation d/t surgery DVT/PE --> inflammation acute MI drug fever transfusion reaction bowel infarction cancer ```

Question 28

What POD would infectious fever present

Answer 28

>POD2

Question 29

7 W's of infection

Answer 29

``` wind - lungs pneumonia water - UTI wound - SSI walking - DVT/PE iatrogenic - drug fever, blood transfusion wings - phlebitis, hardware, drains worry - injury/inflammation d/t surgery ```

Question 30

Benefits of fever

Answer 30

increase motility & activity of WBC | creates inhospitable environment for bacteria

Question 31

Factors increasing metabolic demand

Answer 31

PSR temperature physical activity

Question 32

Determinants of alveolar gas exchange

Answer 32

``` ventilation composition of air (altitude, carbon monoxide) pulmonary perfusion alveolar surface area thin respiratory membrane ```

Question 33

Oxygen demand & temperature

Answer 33

O2 demand increases by 13% for every degree above 37

Question 34

Consequences of fever & hyperthermia

Answer 34

uncomfortable increased energy demand fluid deficit (sweating, RR) impaired perfusion (dehydration) impaired neurologic function (seizures, delirium) cytotoxic (protein denaturation occurs when temp >42 degrees)

Question 35

Methods of temperature measurement

Answer 35

oral axillary (lower than oral) rectal (1 degree higher than oral) tympanic (higher than oral)

Question 36

Diagnostics

Answer 36

``` CBC w/ differential Imaging - CXR Blood cultures Sputum/gram stain Wound culture Urinalysis/culture ```

Question 37

S/S of fever

Answer 37

``` elevated temp >37.8 increased HR, RR chills/shivering red, warm (flushed) skin diaphoresis thirst, dehydration fatigue, myalgia, arthralgia (PGE2 in peripheral tissue) CBC rigors (bacteremia/sepsis) ```

Question 38

Fever interventions

Answer 38

``` anitpyretic medication external cooling --> cloth, ice packs, remove layers, cool fluids increase fluids to compensate for loss encourage rest treat underlying cause ```

Question 39

Aging & Temperature

Answer 39

older adults have lower temps d/t less subq tissue, less skeletal muscle, loss of vasoconstriction capacity, decreased cardiac output, decreased metabolism

Question 40

Peripheral thermoreceptors

Answer 40

skin | *mainly cold receptors

Question 41

Central thermoreceptors

Answer 41

``` hypothalamus spinal cord abdominal viscera great veins (vena cava) *mainly warm receptors ```

Question 42

Normal fluctuations in temperature

Answer 42

age circadium rhythm (lowest morning, highest in late afternoon) menstruation

Question 43

Consequences of malignant hyperthermia

Answer 43

very high temp >40 degrees metabolic acidosis muscle rigidity

Question 44

Mechanism of malignant hyperthermia

Answer 44

genetic defect in calcium channel in the sarcoplasmic reticulum --> after general anesthesia causes an efflux of calcium --> prolonged muscle contractions, hypermetabolism, excess heat production

Question 45

Populations at risk of hyperthermia

Answer 45

infants young children older adults

Question 46

Causes of hypothermia

Answer 46

general/regional anesthesia OR temp intraoperative open body cavity

Question 47

Consequences of hypothermia

Answer 47

myocardial events increased blood loss infection shivering (increase metabolic demand)

Question 48

Hypothermia assessment

Answer 48

temperature <36 decreased HR, RR, BP decreased LOC impaired CWMS (pool, cold, skin, cap refill >3s)