What is the recommended treatment for a patient presenting with fever?

Treatment of Fever: Evidence-Based Approach

Initial Assessment and Temperature Measurement

For accurate fever assessment, use central temperature monitoring (pulmonary artery catheter thermistors, bladder catheters, or esophageal thermistors) when these devices are already in place; otherwise, measure oral or rectal temperatures rather than unreliable axillary or tympanic methods. 1, 2, 3

• Fever is defined as a single temperature measurement ≥38.3°C (101°F) in the ICU setting 3
• Oral temperatures have poor sensitivity for detecting fever, particularly in critically ill patients 4
• Core temperature measurements are essential when accurate readings are critical to diagnosis and management 1, 2
• Elderly and immunocompromised patients may not mount typical fever responses despite serious infection 2

Diagnostic Workup: Systematic Approach

Perform a chest radiograph on all ICU patients with new-onset fever, as pneumonia is the most common infection causing fever in this population. 1, 2, 3

Essential Initial Tests:

• Obtain at least two sets of blood cultures (60 mL total) before starting antibiotics 2, 3
• If a central venous catheter is present, collect simultaneous central and peripheral blood cultures 1, 2
• Chest radiography is mandatory for all febrile ICU patients unless a clear alternative source is identified 1, 3

Advanced Imaging Indications:

• For postoperative patients (thoracic, abdominal, or pelvic surgery): Perform CT imaging in collaboration with surgical services if initial workup fails to identify an etiology 1, 3
• For abdominal symptoms or recent abdominal surgery: Obtain formal bedside diagnostic ultrasound of the abdomen 1, 3
• For persistent fever without identified source: Consider 18F-fluorodeoxyglucose PET/CT if transport risk is acceptable 1
• Thoracic bedside ultrasound is suggested when expertise is available to identify pleural effusions and parenchymal pathology in patients with abnormal chest radiographs 1

Antipyretic Treatment: When and How

Avoid routine use of antipyretic medications solely for temperature reduction in critically ill patients, as this does not improve mortality, hospital outcomes, or shock reversal. 1, 2, 3

Evidence Against Routine Antipyresis:

• A meta-analysis of 13 RCTs (1,963 patients) showed fever management reduced temperature but did not improve 28-day mortality (RR 1.03; 95% CI 0.79-1.35), hospital mortality (RR 0.97; 95% CI 0.73-1.30), or shock reversal (RR 1.11; 95% CI 0.76-1.62) 1, 2
• Fever is an evolved defense mechanism that augments immune cell performance and induces stress on pathogens 5
• Observational trials suggest survival benefit from allowing fever to run its course 5

When to Use Antipyretics:

• For symptomatic relief: When patients or families value comfort and temperature reduction, use antipyretic medications rather than nonpharmacologic cooling methods 1, 2, 3
• For neurological patients: Uncontrolled neurogenic fever can precipitate secondary brain injury; prompt fever treatment is recommended in acute ischemic stroke 2

Special Population: Returned Travelers

For febrile returned travelers, malaria must be excluded first, followed by systematic evaluation for enteric fever, rickettsial infections, and arboviruses based on travel history. 1

Enteric Fever (Typhoid/Paratyphoid):

• First-line empiric treatment: Intravenous ceftriaxone is now preferred over fluoroquinolones for patients returned from Asia, where >70% of S. typhi isolates are fluoroquinolone-resistant 1, 6
• Blood cultures have highest yield within the first week of symptoms (sensitivity 40-80%) 1
• Treatment duration: Continue for 14 days to reduce relapse risk (ceftriaxone <8%, azithromycin <3%) 1
• Azithromycin is a suitable oral alternative for uncomplicated disease when fluoroquinolone resistance is confirmed 1, 6

Rickettsial Infections:

• Common in travelers visiting game parks in southern Africa (R. africae) or Mediterranean regions (R. conorii) 1
• Incubation period: 5-7 days (up to 10 days) 1
• Treatment should be initiated promptly and patients typically respond within 24-48 hours 1

Key Diagnostic Considerations:

• Hepatitis A and E present with flu-like illness followed by jaundice and tender hepatomegaly; diagnosis confirmed by IgM serology 1
• Respiratory symptoms with upper zone infiltrates in Southeast Asian travelers warrant investigation for melioidosis and tuberculosis 1
• Fever with gastrointestinal symptoms: Consider bacterial dysentery (E. coli, Campylobacter, Salmonella, Shigella) or amoebic colitis; empiric cephalosporins or fluoroquinolones are effective, though quinolone resistance is increasing 1

Critical Pitfalls to Avoid

• Do not treat the thermometer reading instead of the patient's symptoms and comfort 3
• Do not delay effective antimicrobial therapy when infection is suspected, as this increases mortality 3
• Do not rely on fever presence alone in elderly or immunocompromised patients, who may have blunted responses 2, 4
• Do not use unreliable temperature measurement methods (tympanic, temporal, axillary) for critical clinical decisions 1, 3
• Do not assume absence of fever rules out infection, particularly in high-risk populations 2, 4

Central Fever (Neurogenic Fever)

Central fever is a diagnosis of exclusion that should only be considered after infectious and other non-infectious causes have been thoroughly ruled out. 2

• Defined as core temperature >37.5°C driven by neurological dysregulation without evidence of sepsis or clinically significant inflammatory processes 2
• Key characteristic: persistent temperature elevations without cyclic pattern 2
• For patients desiring symptomatic relief, antipyretic medications are preferred over non-pharmacologic cooling 2