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Flashcards in hyperthermia/fever Deck (38):
1

where is the thermoregulatory center located?

central nervous system in preoptic area of anterior hypothalamus

2

what is responsible for sensing the changes in ambient and core body temperatures (hint: these things relay information to the anterior hypothalamus via the CNS)

peripheral and central thermoreceptors

3

when ambient temperatures are normal, what is responsible for the body's main source of heat?

muscles

4

definition of hyperthermia?

any elevation in core body temperature above accepted normal range

5

definition of fever?

hyperthermic animals in whom the set point in the AH has been reset to higher temperature

6

t/f: true fever is a normal response of the body to invasion or injury and is part of the acute phase response?

true

7

list other parts of the acute phase response besides fever

increased neutrophil numbers and phagocytosis
enhanced T and B lymphocyte activity
increased acute phase protein production by liver
increased fibroblast activity
increased sleep

8

what is responsible for initiating the acute phase response in fever? list some examples

exogenous pyrogens- infectious agents or their products, immune complex formation, tissue inflammation or necrosis, pharmacologic agents

9

what are the 4 different classifications of hyperthermia and give at least 1 example of each?

true fever- production of endogenous or exogenous pyrogens
inadequate heat dissipation- heat stroke, hyperpyrexic syndromes
exercise-induced hyperthermia- normal exercise, hypocalcemic tetany, seizures
pathologic or pharmacologic origin- lesions around anterior hypothalamus, maligant hyperthermia, hypermetabolic disorders, monoamine metabolism disturbances

10

what are the primary immune cells involved in endogenous pyrogen production?

macrophages

11

List the 11 endogenous pyrogens and their principal source

TNF-a (cachectin)-macrophages
TNF-b (lymphotoxin)- lymphocytes (T and B)
IL-1a- macrophages etc
IL-1b - macrophages, etc
IFNa- leukocytes, espec macrophages
IFNb- fibroblasts
IFNy- T lymphocytes
IL6- many cell types
macrophages inflammatory protein 1a- macrophages
macrophage inflammatory protein 1b- macrophages
IL8- macrophages

12

list examples of bacterial exogenous pyrogens

gram positive and gram negative bacteria

13

list examples of bacterial products that cause exogenous pyrogen production

LPS, streptococcal exotoxin, staph enterotoxin, staph proteins

14

fungi that cause pyrogen production?

fungal products, crypto polysaccharide, crypto proteins

15

nonmicrobial agents that can cause exogenous pyrogen release

soluble Ag-Ab complexes
bile acids
pharmacologic agents
tissue inflammation and necrosis

16

list the mechanisms for heat loss

radiation
conduction
convection
evaporation

17

describe radiation as a mechanism for heat loss

electromagnetic or heat exchange between objects in the environment

18

describe conduction as a mechanism for heat loss

between the body and environmental objects that are in direct contact with the skin, as determined by the relative temperatures and gradients

19

describe convection as a mechanism of heat loss

the movement of fluid, air, or water over the surface of the body

20

describe evaporation as a mechanism of heat loss

disruption of heat by the energy required to convert the material from a liquid to a gas, as with panting

21

Which of the following is not recommended for total body cooling of the heat stroke patient (in this chapter) ;) ?
A- IVF therapy
B- tepid water baths
C- ice water bath
D- placing fan near animals

C

22

Cooling should be discontinued in a heat stroke patient at what temp?

103 F

23

heat stroke is a result of what?

inadequate heat dissipation

24

hyperpyrexic syndrome is associated with what?

moderate to severe exercise and a hot/humid climate

25

list the cooling options for a hyperthermic patient

oxygen and IV fluid therapy
surface cooling techniques
internal cooling techniques
extracorporeal techniques (antipyretic drugs)

26

examples of surface cooling techniques?

clip fur
tepid water applied to skin/body
fan
ice packs over areas with large vessels (neck, axilla, inguinal)

27

examples of internal cooling techniques?

rectal admin of cool isotonic fluids
gastric lavage
open body cavity
peritoneal dialysis

28

examples of antipyretic drugs?

antiprostaglandins, dantrolene, dipyrone, aminoyrine, cox2 inhibitors, glucocorticoids, other NSAIDs

29

name 2 endocrine disorders that can cause increased metabolic rate, vasoconstriction resulting in excessive heat production, decreased ability to dissipate heat?

hyperthyroidism and pheochromocytoma

30

what is the mechanism of malignant hyperthermia?

disturbed calcium metabolism initiated by pharmacologic agents such as inhalation anesthetics (halothane) and muscle relaxants (succinylcholine) can cause myopathy and subsequent metabolic heat production

31

how may phenothiazines be effective in alleviating true fever?

depressing normal thermoregulation and causing peripheral vasodilation

32

list common causes of noninfectious fever in ICU patients

phlebitis, thrombophlebitis, post-operative inflammation, transfusion reactions, pancreatitis, hepatitis, cholecystitis, aspiration pneumonitis, ARDS, neoplasia

33

what is the suspected incidence of nosocomial infections in critically ill human patients?

3-31%

34

common sites for nosocomial infections in critically ill?

lungs (aspiration, VAP), bloodstream, catheters, incisions, urinary tract

35

what are the benefits of a fever?

decreases ability of bacteria to use iron, decreases ability of viruses to replicate, increased leukocyte function

36

detriments to having a fever?

increases tissue metabolism and O2 consumption; raises caloric and water requirements, supression in appetite center; may lead to DIC, arrhythmias, liver complications, GI signs

37

exertional heat stroke and malignant hyperthermia may lead to....

rhabdomyolysis, hyperK, hypoCa, myoglobinemia, myoglobinuria, increased CK

38

body temp >107 F may lead to what specific GI complications

epithelial desquamation, endotoxin absorption, bleeding