Fever and PUO Flashcards
Define PUO?
Prolonged illness (2-3 weeks) Fever (>38.3) on several occasions No diagnosis after intelligent investigations
What is the normal oral temperature range?
35.8-37.8
Describe the diurnal variation in body temperature?
Lowest in morning
Highest in afternoon
Varies by 0.5-1
Where is body temperature regulated?
Anterior hypothalamus
Temperature sensitive neurons
Define fever?
Early morning oral temp > 37.2
Oral temp > 37.8 at any time
Describe how measurement of temperature may vary?
Oral: < core body temp by 0.5
Axillary: < core body temp by 1
Ear probe closer to core temp
What is the optimum temperature for fighting an infection?
39.5
Describe rigor?
Feeling of intense cold Uncontrollable shivering Pallor Pilo-erection Exhaustion afterwards with high fever (>39)
What is the most common cause of fever of short duration?
Infection
Which life-threatening conditions associated with fever of short duration must be detected and treated immediately?
Meningococcaemia Falciparum malaria Bacterial meningitis Post splenectomy sepsis TSS Necrotising soft tissue infections Head and neck space infections Febrile neutropaenia Acute staph aureus endocarditis Severe pneumonia
Describe the symptoms of TSS?
Hypotension
Fever
Rash
Describe the symptoms of necrotising soft tissue infections?
Severe local pains
Fever
Chills
Which patients presenting with fever are most at risk for a serious illness?
Recent OS travel Asplenic Neutropaenic Elderly Diabetic IVDU
Which signs, along with fever, indicate a serious illness in a patient?
Shock
Impaired conscious state
Cyanosis
Tachypnoea
What symptoms that present with acute fever are warning bells?
Rapid onset/evolution Rigors Severe muscle pain Impaired conscious state Vomiting Severe headache Rash Jaundice
Why is vomiting associated with fever an alarm bell?
Vomiting can be associated with raised ICP
Can be caused by toxins
Why is severe headache associated with fever an alarm bell?
Meningitis
Why is jaundice associated with fever an alarm bell?
Can be a marker of sever illness, especially sepsis
Describe the management of a patient that presents with fever?
Investigations: FBE, CRP, renal function, liver function, blood and urine cultures, CXR
Empirical IV antibiotics (if bacterial infection likely)
Admit or prolonged stay in ED
Describe how the WCC and CRP levels may change through the course of an infection?
takes time for immune system to respond > may take up to 12 hours to see elevation
What should be considered in a patient with prolonged fever?
Occupation/animal exposure Country of origin Travel - local or OS for past 2 years Contact with toddlers Risk for SBE New sexual contacts New medications
Why is country of origin important in prolonged infection?
Possibility of TB
Why is any travel in the past two years significant for a patient presenting with prolonged fever?
Vivax malaria has prolonged liver phase
What is the most common cause of prolonged fever in young couples with toddlers?
Acute CMV
Children are fine when infected, but transferred to adults > symptomatic 2-3 weeks later
Describe the investigations that should be carried out on a patient with prolonged fever?
FBE ESR CRP LFT CXR Serology for unusual infections Blood and urine cultures
What may show up on an FBE of a patient with prolonged fever?
Atypical lymphocytosis: infectious mononucleosis (EBV< CMV, HIV)
Neutrophilia: bacterial/inflammatory process
EXCLUDE MALARIA
What would a high ESR indicate in a patient with prolonged fever?
Non-specific
High with prolonged bacterial infection or vasculitis
What would a very high CRP in a patient with prolonged fever suggest?
Bacterial infection/inflammation
Why is a CXR performed in a patient with prolonged fever?
Atypical pneumonia
Why aren’t empirical antibiotics given to a patient with prolonged fever?
Side effects of antibiotic may confuse clinical picture
When would empirical antibiotics be given to a patient with prolonged fever?
If Q fever or atypical pneumonia were highly likely
Describe the clinical approach to diagnosing PUO?
1) Onset and duration (when were they last well?)
2) Seek localising symtpoms
3) Establish severity (weight loss? night sweats?)
4) Is there really a fever?
5) Obtain information and review all results
6) Past Hx, family Hx, medications
7) Country of origin
8) Travel history (last 10 years)
9) Occupation, animal exposure
10) Sexual history and IVDU
What are the differential diagnoses for PUO?
Infections
Connective tissue disorders
Malignancies
Other: drug fever, factitious fever, benign pyrexia
Which infections could cause PUO?
Subacute bacterial endocarditis (SBE) TB Intra-abdominal abscess HIV related opportunistic infection Other: EBV, CMV, brucella, Q fever, malaria
Which connective tissue diseases could cause PUO?
Polymyalgia rheumatica Giant cell arteritis Vasculitis Adult Still's disease SLE Acute thyroiditis Granulomatous diseases: sarcoidosis, Crohn's
Describe the physical examination of a patient with PUO?
Eyes Temporal arteries Teeth and gums Thyroid gland tenderness Heart murmur/rub Lymph nodes Hepatosplenomegaly Kidney mass Rash/arthritis
Describe the investigations for a patient with PUO?
Repeat and review basic bloods and cultures
MSU
ANA, RF, ANCA
Iron studies
LDH, beta 2 microglobulin
HIV serology
Consider serology for EBV, CMV, brucellosis, Q fever, psittacois, bartonella, syphilis
Consider TB
Imaging: CXR, CT abdo/pelvis, PET scanning
Tissue sample if you still don’t have a diagnosis
