Fever
- In febrile infants 0-3 months old:
- Recognize the risk of occult bacteremia.
- Investigate thoroughly (e.g., blood cultures, urine, lumbar puncture +/- chest X-ray).
- In a febrile patient with a viral infection, do NOT prescribe antibiotics.
- In a febrile patient requiring antibiotic therapy, prescribe the appropriate antibiotic(s) according to likely causative organism(s) and local resistance patterns.
- Investigate patients with fever of unknown origin appropriately (e.g., with blood cultures, echocardiography, bone scans).
- In febrile patients, consider life-threatening infectious causes (e.g., endocarditis, meningitis).
- Aggressively and immediately treat patients who have fever resulting from serious causes before confirming the diagnosis, whether these are infectious (e.g., febrile neutropenia, septic shock, meningitis) or non-infectious (e.g., heat stroke, drug reaction, malignant neuroleptic syndrome).
- In the febrile patient, consider causes of hyperthermia other than infection (e.g., heat stroke, drug reaction, malignant neuroleptic syndrome).
- In an elderly patient, be aware that no good correlation exists between the presence or absence of fever and the presence or absence of serious pathology.
General Overview
General Overview
- Fever (usually >38°C) is an elevation in core body temperature seen in infections, autoimmune, autoinflammatory diseases
- Hyperpyrexia (>41.5° C) is seen in severe infection or CNS hemorrhage
- Older adults and patients being treated with biologic agents may have a low-grade fever in serious infection
- Aspirin (NSAIDs) and Acetaminophen are potent antipyretics
- If fever does not change with aspirin/acetaminophen, consider hyperthermia (see below)
Fever Unknown Origin
Fever Unknown Origin
- T>38.3 C for >3w without etiology
Causes
Causes
- Infectious (Endocarditis, TB, osteomyelitis, intraabdominal abscess, dental abscess)
- Malignancies (Hematologic, metastatic, renal cell carcinoma)
- Connective tissue diseases (Giant cell arteritis, PMR, RA, IBD)
- Drug (antibiotics, methyldopa, phenytoin)
- DVT
History
History
- Exposures
- Travel, endemic diseases
- Family history
- Medical history, malignancy
- Surgical history, prosthesis (osteomyelitis)
- Risky behaviours (IVDU, STI exposure)
Physical
Physical
- Rash
- Conjunctivitis, uveitis (autoimmune)
- Hepato-splenomegaly
- Joint swelling
- Lymphadenopathy
Labs to consider
Labs to consider
- Blood cultures r/o endocarditis
- CBC
- ESR/CRP
- LDH
- HIV Ab and Viral load
- RF
- Heterophile antibody test
- CPK
- ANA
- TB skin test (or interferon-gamma release assay)
- Serum protein electrophoresis
Imaging
Imaging
- CT abdo/chest (r/o abscess, malignancy)
- Consider
- Echocardiography (r/o endocarditis)
- PET-CT (r/o malignancy/inflammation)
- Referral to ID, rheumatology, oncology
Hyperthermia
Hyperthermia
- Distinction between Hyperthermia and Fever important
- Hyperthermia (fatal): Thermoregulatory center unchanged despite increasing temperature
- Suspect based on history
- Suspect if skin hot and dry (heat stroke or atropine), or if antipyretics do not decrease body temperature
- Fever: Thermoregulatory center compensates for increasing temperature
- Hyperthermia (fatal): Thermoregulatory center unchanged despite increasing temperature
Management
Management
- Hyperthermia must be treated by RAPID reduction of body temperature by PHYSICAL means → find underlying cause
- Ice packs, cool damp sponges/towels/water, fan
- Avoid cooling blankets (vasoconstriction → less heat loss)
- IV fluids for dehydration
- Ice packs, cool damp sponges/towels/water, fan
Nonexertional/Exertional heat stroke
- Consider heat stroke in T>40C, CNS dysfunction (altered mental status), exposure to heat, and absence of other explanation
- ABC, may need intubation and ventilation
- Rapid cooling and rehydration
- Continuous rectal probe temperature monitoring
- Labs (CBC, lytes, UA, CK, LFT, Coags)
Pharmacology/drug-induced (atropine, ecstasy)
- Charcoal if <1-2h ingestion
- Benzodiazepines for agitation/seizure (eg. lorazepam 1-2mg IV push until hypertension controlled or patient sedated)
- Consult Poison Control Center
- Atropine - consider physostigmine (antidote)
- Ecstasy - only correct hyponatremia if severe/symptomatic
Metabolic disease (hyperthyroid)
- Thyroid storm (suspect in tachycardia, hyperpyerxia, CNS dysfunction, GI symptoms, goiter, hyperthyroidism on labs)
- B-Blockers (Propranolol 60-80mg PO q4-6h)
- PTU 200mg PO q4h
- Iodine solution (delayed 1h after PTU)
- Iodinated radiocontrast
- High-dose IV hydrocortisone 100mg IV q8h
Anesthetics (malignant hyperthermia)
- Discontinue anethestic, add charcoal fibers to anesthesia breathing circuit
- Hyperventilate with 100% O2
- Dantrolene
Neuroleptic (neuroleptic malignant syndrome)
- Discontinue neuroleptic
- Supportive
- Consider dantrolene, bromocriptine, amantadine if do not respond after 1-2 days
Serotonin syndrome
- Diagnose clinically if on serotonergic agent and one of the following:
- Spontaneous clonus
- Inducible clonus PLUS agitation or diaphoresis
- Ocular clonus PLUS agitation or diaphoresis
- Tremor PLUS hyperreflexia
- Hypertonia PLUS temperature above 38°C PLUS ocular clonus or inducible clonus
- Discontinue serotonergic agent
- Supportive care aimed to normalize vital signs
- Benzodiazepine sedation
- Serotonin antagonist
- Consider sedation, paralysis, intubation
- Consider Cyproheptadine (antidote)
References:
- Fever of Unknown Origin
- AAFP 2014. https://www.aafp.org/afp/2014/0715/p91.html
- Heat
- Fever in Children
- CFP 2017. http://www.cfp.ca/content/63/10/756