What is the recommended approach for assessing and managing fever?

Fever Assessment and Management

A new fever should trigger a careful clinical assessment with focused history and physical examination rather than automatic laboratory and radiologic testing, prioritizing cost-conscious evaluation guided by clinical findings. 1

Temperature Measurement and Fever Criteria

Standard Temperature Thresholds

For critically ill adults:

• Pulmonary artery catheter thermistors are the gold standard for core temperature measurement 1
• Bladder catheter thermistors provide essentially identical readings and are less invasive 1

For long-term care facility (LTCF) residents:

• A single oral temperature ≥100°F (37.8°C) is both sensitive (70%) and specific (90%) for predicting infection 1
• Alternative criteria: temperature increase ≥2°F (1.1°C) over baseline, or oral temperature ≥99°F (37.2°C), or rectal temperature ≥99.5°F (37.5°C) on repeated measurements 1
• Rectal measurements are more accurate than oral or axillary methods; electronic techniques are superior to mercury thermometry 1

Initial Clinical Assessment

Focused Physical Examination Components

The examination must systematically evaluate: 1

• Respiratory rate (tachypnea >25 breaths/min has 90% sensitivity and 95% specificity for pneumonia in LTCF residents) 1
• Mental status changes
• Hydration status 1
• Oropharynx and conjunctiva 1
• Skin examination (including sacral, perineal, and perirectal areas; turn patient to assess for pressure ulcers) 1
• Chest auscultation
• Cardiac examination
• Abdominal examination
• All indwelling devices (catheters, lines) 1

Critical History Elements

Identify high-risk conditions and exposures: 1

• Diabetes mellitus (predisposes to skin infections and UTI)
• Chronic obstructive pulmonary disease (pneumonia risk)
• Poor swallowing/gag reflex (aspiration pneumonia)
• Indwelling urinary catheters (39-fold increased bacteremia risk over one year) 1
• Prosthetic devices (septic arthritis risk)
• Altered mental status (aspiration risk)
• Chronic immobility (pressure ulcers)

For fever with rash, document: 2

• Timing of rash relative to fever onset
• Pattern of spread (centrifugal vs. centripetal)
• Involvement of palms and soles
• Recent travel to tropical or endemic areas
• Tick exposures or outdoor activities
• Animal and sick contacts
• Recent medication changes

Silent Sources of Infection

Carefully rule out: 1

• Otitis media
• Decubitus ulcers (sacrum, back, head)
• Perineal or perianal abscesses
• Retained tampons

Adjunctive Diagnostic Markers

Biomarkers for Infection Discrimination

Serum procalcitonin: 1

• Elevations ≥0.5 ng/mL occur within 2-3 hours of onset
• Levels correlate with severity: SIRS (0.6-2.0 ng/mL), severe sepsis (2-10 ng/mL), septic shock (≥10 ng/mL)
• Chronic inflammatory states do not elevate procalcitonin
• Can be employed as an adjunctive diagnostic tool for discriminating infection as the cause of fever 1

Endotoxin activity assay: 1

• High negative predictive value (98.6%) for Gram-negative infection
• Can be used adjunctively for infection discrimination 1

Life-Threatening Causes Requiring Immediate Action

Fever with Petechial/Purpuric Rash

Immediately rule out meningococcemia and Rocky Mountain spotted fever (RMSF): 2

• Do not delay treatment while awaiting laboratory confirmation 2
• For suspected meningococcemia: administer broad-spectrum antibiotics immediately 2
• For suspected RMSF: initiate doxycycline immediately, regardless of patient age 2

RMSF characteristics: 2

• Rash begins as small pink macules on extremities, spreads centrally, becomes petechial
• Palms/soles involvement appears late (days 5-6)
• Thrombocytopenia and mild hepatic transaminase elevations common

Malignant Hyperthermia and Neuroleptic Malignant Syndrome

Consider when fever is especially high: 1

• Malignant hyperthermia can be delayed up to 24 hours post-operatively, especially with steroid use
• Results can be devastating if left untreated

Drug-Induced Fever

Recognition and management: 1

• Can be caused by any drug due to hypersensitivity
• Mean lag time between drug initiation and fever: 21 days (median 8 days)
• Fever takes 1-7 days to resolve after removing offending agent
• Rash and eosinophilia are uncommon
• Diagnosis established by temporal relationship to starting/stopping drug

Special Populations

Returned Travelers

For fever in travelers from tropical areas: 1, 2

• Assess for viral hemorrhagic fever (VHF) risk
• Obtain up to three daily blood films to exclude malaria 1
• Most tropical infections become symptomatic within 21 days of exposure 2
• Three malaria tests over 72 hours may be needed to confidently exclude malaria 2
• Consider dengue if thrombocytopenia present 2

Laboratory safety: 1

• Warn laboratory staff when considering enteric fever, brucella, Q fever, melioidosis, or VHF
• Statutory handling arrangements apply for VHF

Immunocompromised Patients

Modified approach required: 2

• May present with atypical or more severe manifestations
• Lower threshold for hospitalization and empiric antimicrobial therapy

Resource-Conscious Testing Strategy

The fundamental principle: 1

• Clinical assessment should guide selective testing rather than automatic order sets
• Avoid time-consuming, costly tests that disrupt patient care and expose patients to unnecessary radiation, transport risks, and blood loss
• Obtain cultures and imaging only when clinically indicated after focused evaluation