What is the approach to taking a fever history in a patient?

Approach to Taking a Fever History in a Patient

A thorough fever history should begin with a focused assessment of potential infectious and non-infectious causes, including careful examination of mental status, oropharynx, skin, chest, abdomen, and perineum, rather than automatically ordering extensive laboratory and radiologic tests. 1

Initial Assessment Components

Temperature Measurement

• Use central temperature monitoring methods when available:
  • Thermistors in pulmonary artery catheters
  • Bladder catheters with thermistors
  • Esophageal balloon thermistors 1
• If these devices aren't in place, prioritize:
  • Oral temperatures (more reliable)
  • Rectal temperatures (most accurate in elderly patients)
  • Avoid less reliable methods: axillary, tympanic membrane, temporal artery, or chemical dot thermometers 1

Definition of Fever

• In general adult patients: Temperature >38.3°C (>100.9°F)
• In elderly patients (especially in long-term care):
  • Single temperature >37.8°C (>100°F) is both sensitive (70%) and specific (90%) for infection
  • Alternatively, an increase of at least 1.1°C (2°F) over baseline 1

Key History Elements

1. Timing and Pattern:

   • Onset (acute vs. gradual)
   • Duration (acute, persistent, recurrent)
   • Pattern (continuous, intermittent, remittent, hectic)
   • Relationship to time of day

2. Associated Symptoms:

   • Respiratory: cough, shortness of breath, chest pain
   • Gastrointestinal: diarrhea, abdominal pain, nausea/vomiting
   • Genitourinary: dysuria, frequency, urgency
   • Neurological: headache, altered mental status, neck stiffness
   • Skin: rash, wounds, pressure ulcers

3. Recent Procedures and Devices:

   • Surgery within past 60 days
   • Indwelling catheters or lines (urinary, central venous)
   • Prosthetic devices (joints, heart valves)
   • Recent transfusions 1

4. Medication Review:

   • Recent antibiotics (especially for C. difficile risk)
   • Immunosuppressants
   • New medications (for drug fever)
   • Chemotherapy agents 1

5. Underlying Conditions:

   • Diabetes (predisposes to skin infections and UTIs)
   • COPD (predisposes to pneumonia)
   • Poor swallowing/gag reflex (aspiration risk)
   • Chronic immobility (pressure ulcer risk) 1

Physical Examination Focus

The physical examination should be directed and focused on the most likely sources of infection:

1. Mental Status: Changes may indicate CNS infection, sepsis, or metabolic disturbances

2. Skin:

   • Inspect all skin surfaces, including back and sacrum for pressure ulcers
   • Check all surgical sites and drain sites
   • Examine IV sites for phlebitis or infection

3. HEENT:

   • Oropharynx for mucositis, thrush
   • Sinuses for tenderness
   • Conjunctiva for redness
   • Ears for otitis media

4. Respiratory:

   • Lung sounds for rales, rhonchi
   • Respiratory rate and effort
   • Oxygen saturation

5. Cardiovascular:

   • Heart sounds for new murmurs (endocarditis)
   • Peripheral pulses and edema

6. Abdomen:

   • Tenderness, distension
   • Hepatosplenomegaly
   • Surgical wounds

7. Genitourinary/Rectal:

   • Perineum and perirectal area for abscesses
   • Presence of catheters and entry site appearance 1

Common Pitfalls to Avoid

1. Reflexive Testing: Avoid automatic order sets triggered by fever alone; instead, use clinical assessment to guide targeted testing 1

2. Overlooking Non-Infectious Causes: Consider the extensive list of non-infectious etiologies including:

   • Acalculous cholecystitis
   • Blood product transfusions
   • Drug fever
   • Venous thrombosis
   • Withdrawal syndromes
   • Malignancy
   • Autoimmune conditions 1

3. Inadequate Evaluation in Elderly: Elderly patients, especially in long-term care facilities, often receive incomplete fever evaluations. Be aware that:

   • Presentations may be atypical (only 30% of UTIs present with fever in elderly)
   • Respiratory infections more often present with classic symptoms (cough 75%, fever 62%) 1

4. Missing Silent Sources: Pay special attention to:

   • Otitis media
   • Decubitus ulcers
   • Perineal/perianal abscesses
   • Retained foreign bodies 1

Diagnostic Approach After History and Physical

Based on the history and physical findings, direct further evaluation toward suspected sources:

1. If respiratory symptoms or abnormal chest exam:

   • Obtain chest imaging (radiograph or CT)
   • Collect respiratory secretions for culture before antibiotic changes 1

2. If abdominal symptoms, recent surgery, or liver function abnormalities:

   • Consider abdominal ultrasound or CT imaging 1

3. If diarrhea and recent antibiotics:

   • Test for C. difficile (most common enteric cause of fever in hospitalized patients) 1

4. If urinary symptoms or catheter present:

   • Urinalysis and urine culture
   • Consider catheter replacement if long-term catheter present 1

By following this structured approach to fever history taking, clinicians can efficiently identify the most likely sources of infection or non-infectious causes, leading to appropriate diagnostic testing and timely treatment decisions.