What is the management approach for pneumonitis?

Management of Pneumonitis

Critical First Step: Identify the Type of Pneumonitis

The management of pneumonitis fundamentally depends on distinguishing between infectious pneumonia, drug-related pneumonitis (DRP), and hypersensitivity pneumonitis (HP), as each requires distinctly different therapeutic approaches. 1

For Drug-Related Pneumonitis (Most Relevant to Modern Practice)

Immediately discontinue the offending drug and initiate corticosteroids for moderate-to-severe cases (National Cancer Institute grade 2-4), as delayed diagnosis leads to irreversible fibrosis and worse outcomes. 1

Severity-Based Treatment Algorithm:

• Grade 1 (Asymptomatic): Withhold drug temporarily, monitor closely with serial imaging 1

• Grade 2 (Symptomatic, not interfering with ADLs):

  • Discontinue drug permanently 1
  • Start prednisone 0.5-1 mg/kg/day 1
  • Provide supplemental oxygen to maintain SpO2 >92% 1

• Grade 3-4 (Severe, life-threatening):

  • Permanently discontinue drug 1
  • Hospitalize immediately 1
  • High-dose IV methylprednisolone 1-2 mg/kg/day 1
  • Supplemental oxygen or mechanical ventilation as needed 1
  • If no improvement after 48 hours on corticosteroids, add infliximab, mycophenolate mofetil, or IV immunoglobulin 1

Special Considerations for Immune Checkpoint Inhibitor (ICI) Pneumonitis:

• All major oncology societies (NCCN, ASCO, SITC, ESMO) recommend discontinuing ICI therapy for ANY grade of pneumonitis 1
• Grade 3-4 ICI pneumonitis requires permanent discontinuation 1
• Corticosteroid therapy mandatory for grade 2 or higher 1

For Hypersensitivity Pneumonitis

Antigen avoidance is the cornerstone of management and must be implemented immediately upon diagnosis. 2, 3

Treatment Approach:

• Identify and eliminate antigen exposure through detailed environmental/occupational history 2, 3
• Corticosteroids commonly used but lack proven long-term efficacy in preventing fibrotic progression 2
• For progressive fibrotic HP: Consider nintedanib (FDA-approved for chronic fibrosing ILDs with progressive phenotype) 2
• Non-pharmacological interventions: oxygen therapy, pulmonary rehabilitation, supportive care 2

For Community-Acquired Pneumonia (Infectious Pneumonitis)

Oxygen Therapy (Universal Priority):

• Maintain PaO2 >8 kPa and SpO2 >92% 1, 4
• High-concentration oxygen safe in uncomplicated pneumonia 1
• In COPD patients with pneumonia: Use controlled oxygen guided by repeated arterial blood gases to avoid hypercapnia 5

Supportive Care:

• Assess for volume depletion; administer IV fluids as needed 1
• Nutritional support in prolonged illness 1
• Monitor temperature, respiratory rate, pulse, BP, mental status, oxygen saturation at least twice daily (more frequently in severe cases) 1, 5

Antibiotic Selection:

• Outpatient mild CAP: Amoxicillin (higher doses than historically used) 1, 4
• Hospitalized non-severe CAP: Combination therapy with amoxicillin plus macrolide (erythromycin or clarithromycin) 1, 4
• Severe CAP requiring ICU: Broad-spectrum β-lactam plus macrolide or fluoroquinolone 4
• COPD with severe CAP: Piperacillin-tazobactam 3.375g IV q6h plus azithromycin 500mg IV daily for ≥2 days, then 500mg PO daily 5

Treatment Duration:

• Minimum 5 days, afebrile for 48-72 hours, with no more than one sign of clinical instability 4
• Generally should not exceed 8 days in responding patients 4

Monitoring and Reassessment

• Reassess at 48-72 hours: If not improving, obtain repeat chest radiograph to evaluate for complications (pleural effusion, progression) 1, 6
• Remeasure CRP in patients not progressing satisfactorily 1
• Consider bronchoscopy for retained secretions, culture samples, or persistent symptoms at 6 weeks 1

Critical Pitfalls to Avoid

• Do not delay drug discontinuation in suspected DRP: Delayed diagnosis associated with irreversible fibrosis 1
• Do not assume radiologic improvement parallels clinical improvement: Radiographic changes lag behind clinical recovery 1
• Preexisting ILD increases DRP risk 4.8-25.3 fold: These patients require heightened surveillance 1
• In COPD patients: Avoid uncontrolled high-flow oxygen without blood gas monitoring (risk of hypercapnic respiratory failure) 5

Discharge and Follow-Up

• Eligible for discharge when: overall clinical improvement, decreased fever for 12-24 hours, SpO2 >90% on room air for 12-24 hours 1, 4
• Arrange clinical review at 6 weeks with repeat chest radiograph for high-risk patients (smokers, age >50, persistent symptoms) 1, 4, 6