What is the best approach to manage a patient with fever and no significant medical history?

Axillary Temperature Measurement for Fever

Axillary temperature measurement is discouraged and should be avoided for fever assessment in adults, as it does not accurately reflect core body temperature and may lead to missed diagnoses. 1

Preferred Temperature Measurement Methods

Use oral or rectal temperatures instead of axillary measurements for reliable fever detection. 1, 2

Temperature Measurement Hierarchy (Best to Worst):

1. Central monitoring methods (when devices already in place): 1

   • Pulmonary artery catheter thermistors
   • Bladder catheter thermistors
   • Esophageal balloon thermistors

2. Oral or rectal temperatures (for patients without central monitoring): 1, 2

   • These are the recommended standard methods
   • Rectal measurements should be avoided in neutropenic patients due to infection risk 1

3. Unreliable methods to AVOID: 1, 2

   • Axillary temperatures
   • Tympanic membrane temperatures
   • Temporal artery thermometers
   • Chemical dot thermometers

Fever Definitions

• Single oral temperature ≥38.3°C (101°F), OR 1
• Temperature ≥38.0°C (100.4°F) sustained over 1 hour 1, 2

Initial Diagnostic Workup for Fever Without Obvious Source

Immediate Actions:

1. Obtain accurate temperature using oral or rectal route 1, 2

2. Perform chest radiograph as initial imaging for all febrile patients 1, 2

3. Obtain at least two sets of blood cultures (ideally 60 mL total) from different anatomical sites if septic shock present or if results will change management 2

4. Order basic laboratory tests: 2

   • Complete blood count
   • Comprehensive metabolic panel
   • Urinalysis

Clinical Assessment Priorities:

Focus your history and physical examination on these specific elements: 1

• Recent surgical procedures (thoracic, abdominal, pelvic) - if present, obtain CT imaging if initial workup unrevealing 1
• Presence of indwelling devices (central venous catheters, urinary catheters) 1
• Immunocompromised status (neutropenia, HIV, immunosuppressive medications) 1
• Focal neurologic findings or altered mental status - consider lumbar puncture for CNS infection 3
• Abdominal symptoms or liver function abnormalities - obtain formal bedside ultrasound 1

Fever Management Approach

Treat fever primarily for patient comfort, NOT routinely to normalize temperature. 2, 4

Antipyretic Use:

• Avoid routine antipyretic medications specifically for temperature reduction in critically ill patients 1, 2
• If patient desires comfort and temperature reduction, use pharmacologic antipyretics (e.g., ibuprofen, acetaminophen) rather than physical cooling methods 1, 2, 4
• Physical cooling methods cause significant patient discomfort, increase metabolic demand, and do not improve clinical outcomes 4

Critical Pitfalls to Avoid

• Never rely on axillary temperatures for diagnostic decisions - they have poor sensitivity and may miss true fever 1, 2
• Do not aggressively treat fever with antipyretics or cooling devices unless for patient comfort - this does not improve mortality and may impair immune response 2, 4
• Do not delay identification and treatment of underlying cause while focusing on temperature control - fever management is symptomatic, not curative 4
• Avoid automatic order sets triggered by fever alone - perform clinical assessment first to guide targeted testing 1
• Remember that fever may be absent in true infection, especially in elderly and immunocompromised patients 5

Special Populations

Neutropenic Patients:

• Initiate empirical antibiotic therapy urgently (within 2 hours) after presentation 1
• Avoid rectal temperature measurements and rectal examinations 1

Post-Surgical Patients:

• Perform CT imaging (in collaboration with surgical service) if fever etiology not identified by initial workup 1

Patients with Central Venous Catheters:

• Obtain simultaneous central and peripheral blood cultures to calculate differential time to positivity 1
• Sample at least two lumens when obtaining catheter cultures 1