Hyperthermia and Fever Flashcards
Above what temperature is considered elevated?
Above 39.2
Source - CCM
Where is the thermoregulatory control centre?
Preoptic area of the anterior hypothalamus.
Source - CCM
What is the difference between hyperthermia and fever?
hyperthermia encompasses all increases in temperature. Fever denotes only those in which the AH setpoint has been increased. Fever is the normal response to invasion or injury. Fever and other parts of the acute-phase response are initiated by exogenous pyrogens that lead to the release of endogenous pyrogens.
Source - CCM
Do exogenous pyrogens alone induce a fever?
No – they in turn result in the release of endogenous pyrogens.
Source - CCM
What are the most important fever inducing cytokines?
IL-1, IL-6 and TNFa these cytokines travel to the endothelium within the AH and stimulate the release of prostaglandins raising the set point.
Source - CCM
What are the mechanisms of heat loss?
Radiation Conduction Convection Evaporation Source - CCM
What is hyperpyrexic syndrome?
When large dogs undergo extreme exercise in humid environments and vasodilate to musculature and vasoconstrict to cutaneous vessels further compounding reduced heat loss.
Source - CCM
What are some total body cooling techniques?
Surface Cooling Techniques Clip fur if indicated Tepid water applied to skin or whole body (manually or via bath) Fan Ice packs over areas with large vessels (neck, axilla, inguinal region) Combination of above techniques Internal Cooling Techniques Rectal administration of cool isotonic fluids Gastric lavage Open body cavity Peritoneal dialysis Extracorporeal Techniques Antipyretic Drugs Antiprostaglandins Dantrolene Dipyrone Aminopyrine COX-2 inhibitors Glucocorticoids Additional NSAIDs
Source - CCM
What are three examples of pathologic or pharmacologic hyperthermia?
hypothalamic lesions, Malignant hyperthermia, pheochromocytoma, hyperthyroidism
Source - CCM
What is the benefit of a fever?
Reduces bacterial ability to utilise iron – necessary for survival and replication. Many viruses are also heat sensitive – unable to reproduce in high temperatures.
Source - CCM
What are the detrimental effects of a fever?
increases O2 consumption, suppression of appetites, above 41.6 degrees cellular O2 consumption will often outstrip supply resulting in DIC, MODS
Source - CCM
When should non-specific therapy for febrile patients be considered?
When temperatures exceed 41.6 as they risk permanent organ damage.
Source - CCM
Should a fan be utilised for febrile patients?
No. Total body cooling with water, fans, or both in a febrile patient will reduce body temperature; however, the thermoregulatory center in the hypothalamus will still be directing the body to increase the body temperature. This may result in a further increase in metabolic rate, oxygen consumption, and subsequent water and caloric requirements. Unless a fever is life threatening, this type of nonspecific therapy is counterproductive.
Source - CCM
