hyperthermia/fever

Question 1

where is the thermoregulatory center located?

Answer 1

central nervous system in preoptic area of anterior hypothalamus

Question 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)

Answer 2

peripheral and central thermoreceptors

Question 3

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

Answer 3

muscles

Question 4

definition of hyperthermia?

Answer 4

any elevation in core body temperature above accepted normal range

Question 5

definition of fever?

Answer 5

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

Question 6

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

Answer 6

true

Question 7

list other parts of the acute phase response besides fever

Answer 7

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

Question 8

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

Answer 8

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

Question 9

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

Answer 9

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

Question 10

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

Answer 10

macrophages

Question 11

List the 11 endogenous pyrogens and their principal source

Answer 11

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

Question 12

list examples of bacterial exogenous pyrogens

Answer 12

gram positive and gram negative bacteria

Question 13

list examples of bacterial products that cause exogenous pyrogen production

Answer 13

LPS, streptococcal exotoxin, staph enterotoxin, staph proteins

Question 14

fungi that cause pyrogen production?

Answer 14

fungal products, crypto polysaccharide, crypto proteins

Question 15

nonmicrobial agents that can cause exogenous pyrogen release

Answer 15

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

Question 16

list the mechanisms for heat loss

Answer 16

radiation
conduction
convection
evaporation

Question 17

describe radiation as a mechanism for heat loss

Answer 17

electromagnetic or heat exchange between objects in the environment

Question 18

describe conduction as a mechanism for heat loss

Answer 18

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

Question 19

describe convection as a mechanism of heat loss

Answer 19

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

Question 20

describe evaporation as a mechanism of heat loss

Answer 20

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

Question 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

Answer 21

C

Question 22

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

Answer 22

103 F

Question 23

heat stroke is a result of what?

Answer 23

inadequate heat dissipation

Question 24

hyperpyrexic syndrome is associated with what?

Answer 24

moderate to severe exercise and a hot/humid climate

Question 25

list the cooling options for a hyperthermic patient

Answer 25

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

Question 26

examples of surface cooling techniques?

Answer 26

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

Question 27

examples of internal cooling techniques?

Answer 27

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

Question 28

examples of antipyretic drugs?

Answer 28

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

Question 29

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

Answer 29

hyperthyroidism and pheochromocytoma

Question 30

what is the mechanism of malignant hyperthermia?

Answer 30

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

Question 31

how may phenothiazines be effective in alleviating true fever?

Answer 31

depressing normal thermoregulation and causing peripheral vasodilation

Question 32

list common causes of noninfectious fever in ICU patients

Answer 32

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

Question 33

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

Answer 33

3-31%

Question 34

common sites for nosocomial infections in critically ill?

Answer 34

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

Question 35

what are the benefits of a fever?

Answer 35

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

Question 36

detriments to having a fever?

Answer 36

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

Question 37

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

Answer 37

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

Question 38

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

Answer 38

epithelial desquamation, endotoxin absorption, bleeding