ODR - Hyperthermias

Question 1

Define hyperpyrexia

Answer 1

Situation where the hypothalamic set point is raised - infection

Question 2

Define hyperthermia

Answer 2

Elevation of body temperature due to inability to control systems to function

Imbalance between factors warming up and cooling down body

Question 3

CVS effects of hyperthermia

Answer 3

Tachycardia, raised cardiac outpuot
Low SVR –> hypotension

Failure to resuscitate –> cold and clammy

Question 4

Metabolic effects of hyperthermia

Answer 4

Tissue oxygen demand +++

Rise in BMR

Right shift of curve to offset –> increased O2 availability

Question 5

Immune effects of hyperthermia

Answer 5

Temperature sensitive pathogens are compromised

Leucocyte activity increased –> increased response to infection

Question 6

How does pyrexial affect critical illness

Answer 6

Usually sepsis.

Temp regulated by hypothalamus

Cytokines from sepsis –> arachidoic acid pathway –> heat produces by PGE2

Question 7

Managment of pyrexia

Answer 7

1) Minimise heat gain –> environmental factors – bed clothes, heaters, etc
?limit shivering –> clonidine/dexmed

2) treat the cause –> drain collections, Abx etc

3) drugs –> paracetamol resets set point –> no mort benefit
Dantrolene when indicated

4) physical methods

Question 8

Physical methods

Answer 8

Cooling rather than enhancing heat loss

Fan/cool air
Cold packs
Cold blankets
Bladder and abodminal irrigation

Extracorporeal methods

Purpose built methods - artic sun, cool guard