What are the management guidelines for pneumonia, including evaluation, risk assessment, and treatment?

Pneumonia Management Guidelines

The management of pneumonia requires a structured approach including proper diagnosis, risk assessment, and appropriate antimicrobial therapy based on severity and likely pathogens. 1, 2

Types and Definitions

• Community-acquired pneumonia (CAP) is defined as an acute infection of the pulmonary parenchyma with symptoms of acute infection and presence of an infiltrate on chest radiograph or consistent auscultatory findings 2
• Nosocomial pneumonia occurs in hospitalized patients and requires different management approaches than CAP 2
• Pneumonia can be classified by causative organism (bacterial, viral, fungal) with Streptococcus pneumoniae being the most common identifiable bacterial pathogen 2, 3
• Up to 40% of CAP with identified pathogens are caused by viruses, with S. pneumoniae identified in approximately 15% of cases with known etiology 3

Diagnostic Evaluation

• Diagnosis requires at least two signs (temperature >38°C or ≤36°C, abnormal leukocyte count) or symptoms (new/increased cough, dyspnea) plus consistent radiographic findings 3, 1
• Chest radiograph is essential for confirming diagnosis, though sensitivity is only 46-77% 4, 5
• Clinical gestalt using a combination of history and physical examination remains crucial, as chest radiographs may be negative particularly in elderly patients or early disease 4
• Tachypnea is a particularly important vital sign to assess as it correlates with disease severity 1
• Multilobar involvement on chest radiograph is associated with increased severity and poorer prognosis 1

Risk Assessment

• The Pneumonia PORT prediction rule stratifies patients into 5 severity classes to guide site-of-care decisions 2
• Risk class I (lowest severity): age <50 years, no major comorbidities, normal vital signs and mental status 2
• Risk classes II-V are determined by points assigned for demographic variables, comorbidities, physical examination findings, and laboratory/radiographic results 2
• Factors independently associated with increased mortality include:
  • Comorbidities: active malignancies, immunosuppression, neurological disease, heart failure, coronary artery disease, diabetes 2
  • Signs/symptoms: dyspnea, altered mental status, hypothermia/hyperthermia, tachypnea, hypotension 2
  • Laboratory findings: hyponatremia, hyperglycemia, azotemia, hypoalbuminemia, hypoxemia, liver function abnormalities 2

ICU Admission Criteria

• Major criteria (any one): need for mechanical ventilation or septic shock requiring vasopressors 2
• Minor criteria (two or more): systolic BP <90 mmHg, multilobar disease, PaO2/FiO2 ratio <250 2
• Alternative criteria (two or more): respiratory rate >30/min, diastolic BP <60 mmHg, BUN >19.1 mg/dL, confusion 2

Management Guidelines

Outpatient Treatment

• For patients without comorbidities: macrolide (azithromycin, clarithromycin), doxycycline, or respiratory fluoroquinolone 1, 2
• Empirical therapy should be initiated promptly based on likely pathogens 2, 1

Hospitalized Non-ICU Patients

• Intravenous β-lactam (cefotaxime, ceftriaxone, or β-lactam/β-lactamase inhibitor) plus a macrolide OR respiratory fluoroquinolone alone 1, 2
• First dose of antibiotics should be administered within 8 hours of hospital arrival 1, 2

ICU Patients

• Without Pseudomonas risk: intravenous β-lactam plus either macrolide or fluoroquinolone 1
• With Pseudomonas risk: antipseudomonal β-lactam plus either antipseudomonal quinolone or aminoglycoside plus macrolide 1
• For nosocomial pneumonia: piperacillin-tazobactam at 4.5 grams every six hours plus an aminoglycoside 6

Monitoring and Duration of Therapy

• Most patients show clinical improvement within 3-5 days of appropriate therapy 1
• Switch from intravenous to oral therapy when patient has:
  • Improved cough and dyspnea
  • Temperature <100°F on two occasions 8 hours apart
  • Decreasing white blood cell count
  • Functioning gastrointestinal tract with adequate oral intake 1
• Total duration of therapy is typically 5-7 days for uncomplicated cases 1
• Patient should be afebrile for 48-72 hours and have no more than one sign of clinical instability before discontinuing treatment 7

Special Considerations

• For patients with suspected drug-resistant S. pneumoniae, consider β-lactams (amoxicillin, cefotaxime, ceftriaxone) as drugs of choice 2
• Pneumococcal vaccination is recommended for at-risk populations, along with annual influenza vaccination and smoking cessation 1
• Pleural effusions may require additional evaluation, particularly if the patient is not responding to therapy 1
• Radiographic clearing typically lags behind clinical improvement, with only 60% of otherwise healthy patients under 50 years showing complete resolution at 4 weeks 1

Performance Indicators

• Collection of blood culture specimens before antibiotic treatment 2
• Institution of antibiotic treatment within 8 hours of hospitalization 2
• Laboratory tests for Legionella in ICU patients 2
• Demonstration of an infiltrate on chest radiographs of patients with pneumonia diagnosis 2
• Measurement of blood gases or pulse oximetry within 24 hours of admission 2