Pyrexial Illness - 118 Flashcards
What defines an intermittent fever?
Temp. returns to normal at least once every 24 hours.
What is PUO?
Pyrexia of Unknown Origin. Patient has a fever but there is no known cause of it.
What defines a remittent fever?
Temp. does not return to normal but varies a few degrees in either direction.
What is the relationship between temperature and HR?
Elevation of 1*C causes a 15 bpm increase.
How is body temperature regulated?
Heat sensitive receptors in pre-optic area of anterior hypothalamus - sensitive to increase in blood temp., increase signal output when temp rises above 37.1, vice versa. With increase in temp SNS inhibited causing vasodilation, sweating etc. Opposite when temp decreases.
Which cytokines are pyrogenic? How is fever initiated?
IL-6, TNF-a, IL-1, IFN.
Endogenous/exogenous pyrogens presented to host cells, pyrogenic cytokines released into circulation, sensed by hypothalamus which releases PGE2, cAMP elevates thermoregulatory set point - FEVER.
NSAIDs and aspirin are what kind of drug? What do they act on?
Antipyretics. Affect the release of PGE2 to reduce fever.
Why can fever be beneficial?
Liver produces lots of acute phase proteins (C-reactive protein) in response to pyrogenic cytokines. These stimulate pathogen opsonisation and killing.
Neutrophils optimum temperature is higher than normal body temp.
What is the difference between hyperthermia as a cause of fever and a febrile response to a pathogen?
Hyperthermia = pathological increase in temperature without a change in set point of hypothalamic regulatory centre.
Fever is a regulated increase in temperature.
What does IL-10 do?
It is an endogenous antipyretic
What are the four phases of the clinical presentation of fever?
Predromal phase (headache, malaise,aching) Chill phase (chills, shaking, vasoconstriction & piloerection) Flush phase (skin warm -cutaneous vasodilation) Defervescence phase (initiation of sweating)
What are the red flag symptoms for a child presenting with fever?
Vomiting, breathlessness, drowsiness/unresponsive, rash, flopiness, convulsions, not drinking and high pitched or weak cry.
What tests could you carry out on a child presenting with fever?
Urinalysis, bloods (FBC, U+E, CRP, ESR), blood culture, CXR and lumber puncture.
If a patient has a fever and in their medical notes it says that they had a blood transfusion prior to 1985 what would you need to investigate/consider?
HIV-related fever
Older patients that had rheumatic fever when younger are at higher risk of what?
Infective endocarditis
