Fever Flashcards
What is PUO?
Pyrexia of Unknown Origin
how is PUO defined?
Prolonged Illness (2-3 weeks)
Fever (above 38.3C)
No diagnosis after exhaustive investigation
what is the normal range for oral temperature?
35.8 - 37.8
when is body temperature the lowest?
morning
where is body T regulated?
Anterior Hypothalamus
mechanisms of heat loss include?
peripheral vasodilation, sweating and reduced physical activity
heat production mechanisms include?
shivering and increasing metabolic rate
release of thyroid hormone
glucocorticoids
catecholamines [epinephrine, norepinephrine, dopamine]
what is the definition of fever?
oral morning Tem > 37.2
oral Temperature > 37.8
what is the difference between oral and axillary Temps with core Temp?
oral <1
why is increasing temperature a physiological mechanism?
because some immune activities are best functional at 39.5 [immune, endocrine, physiological]
also bacteria tend to work less effectively at higher temps
main inducers of fever?
TNFa
IL-1ß
IL-6
IFN-y
how is the effect of cytokines mediated in the anterior hypothalamus?
inducing of COX-2 and breaking down of membrane arachidonic acid to produce PGE2 (prostaglandin)
Describe Rigor
feeling of uncontrolled shivering and intense cold sensation with pallor and pilo-erection. Main mechanism used to INCREASE BODY TEMP
during the rigor phase of a fever temp is high T/F
F, temp is normal and increases afterwards
sudden sustained fever with the patient coming into the ER must be treated by
Resuscitation
stabilisation
Empirical Antibiotics (check for risks in order to establish this)
some of the alarm bells that indicate serious infection in re: fever
rapid onset/evolution rigors severe muscle pains impaired conscious state vomiting (sign of ICP) severe headache rasch jaundice
investigation of acute serious fever
FBE, CRP, renal/liver function
blood culture, urine culture
CXR
if WCC and CRP are fine then the patient does not have an infection, specially if it recedes with panadol and IV fluid T/F
F, some parameters only increase around 12 hours
for prolonged fever empirical antibiotics are recommended?
NOT, unless Q fever or atypical pneumonia likely
BETTER to test the patient first UNLESS Hx of travel to plasmodium vivas country (2 years B4)
clinical approach to PUO
start again 1 onset and duration 2 seek localising symptoms 3 establish severity 4 is there really a fever? 5 obtain info and review all results 6 look for clues, past Hx Fx Mx 7 country of origin 8 travel Hx 9 occupation, animal exposure 10 Secual Hx and IV drug use
pyrexia associated with a history of handling cattle
Q fever caused by Coxiella burnetii
respiratory disease The most common manifestation is mild flu-like symptoms with abrupt onset of fever, malaise, profuse perspiration, severe headache, myalgia (muscle pain), joint pain, loss of appetite, upper respiratory problems, dry cough, pleuritic pain, chills, confusion and gastrointestinal symptoms, such as nausea, vomiting and diarrhea. The fever lasts approximately seven to 14 days. can also produce atypical pneumonia
what are the most common causes PUO?
30 infectious
30 autoimmune
30 malignancies
10 other
what is benign pyrexia?
mild fever with no apparent cause
what is the most common cause of malignancy PUO
lymphomas
