Critical Alerts

• Acute exacerbation of ILD carries 50% mortality and requires ICU management
• Hypoxemic respiratory failure is the primary emergency presentation
• Avoid high FiO2 in patients with known CO2 retention
• Pulmonary hypertension is common in advanced ILD and affects management
• Infections trigger most acute exacerbations - investigate thoroughly

Key Diagnostics

• ABG/VBG for oxygenation and acid-base status
• Chest X-ray: Reticular opacities, reduced lung volumes
• CT chest (HRCT): Specific patterns guide diagnosis (e.g., UIP, NSIP)
• BNP/NT-proBNP for right heart failure assessment
• Sputum culture and viral panel for infectious triggers

Emergency Treatments

• Supplemental oxygen: Target SpO2 88-92% (avoid hyperoxygenation)
• Acute exacerbation: High-dose methylprednisolone 500-1000mg IV daily for 3 days
• Infection: Empiric antibiotics covering typical and atypical pathogens
• Respiratory failure: NIV or mechanical ventilation with lung-protective strategy
• Pulmonary hypertension crisis: Avoid hypoxemia, consult pulmonology

Interstitial lung disease (ILD), also known as diffuse parenchymal lung disease (DPLD), encompasses a heterogeneous group of over 200 disorders affecting the lung parenchyma with varying degrees of inflammation and fibrosis. The interstitium includes the space between the alveolar epithelium and capillary endothelium.

Classification

Idiopathic Interstitial Pneumonias (IIPs)

ILD with Known Causes

• Connective tissue disease-associated: Rheumatoid arthritis, systemic sclerosis, SLE, dermatomyositis
• Environmental/Occupational: Asbestosis, silicosis, coal worker's pneumoconiosis
• Drug-induced: Amiodarone, methotrexate, nitrofurantoin, bleomycin
• Radiation-induced: Post-thoracic radiation
• Hypersensitivity pneumonitis: Bird fancier's lung, farmer's lung

Granulomatous ILDs

• Sarcoidosis
• Hypersensitivity pneumonitis

Epidemiology (IPF as prototype)

• Incidence: 3-9 per 100,000 per year
• Prevalence: 14-43 per 100,000
• Age: Typically >50 years; increases with age
• Sex: Male predominance (1.5-2:1)
• Median survival (IPF): 3-5 years from diagnosis

Critical Warning Signs

Acute Exacerbation of IPF (AE-IPF)

Clinical Criteria

1. Known IPF diagnosis (or concurrent diagnosis)
2. Unexplained worsening or development of dyspnea within 30 days
3. CT: New bilateral ground-glass opacity and/or consolidation superimposed on UIP pattern
4. Not explained by heart failure or fluid overload

Categories

• Triggered (infection, aspiration, post-procedural)
• Idiopathic (no identifiable trigger)

Acute Presentations

Chronic ILD Differential

Emergency Department Evaluation

Priority Assessment

1. Oxygenation status (SpO2, ABG)
2. Work of breathing
3. Hemodynamic stability
4. Presence of triggers (infection, PE)

Laboratory Studies

Imaging

Chest X-ray

• Reduced lung volumes
• Reticular or reticulonodular opacities
• Lower zone predominance (IPF)
• New infiltrates in acute exacerbation

High-Resolution CT (HRCT) Essential for diagnosis and characterization:

CT for Acute Exacerbation

• New bilateral ground-glass opacities
• New consolidation
• Superimposed on underlying fibrotic pattern

Pulmonary Function Tests (if available/known)

Restrictive Pattern

• Reduced TLC (<80% predicted)
• Reduced FVC
• Normal or elevated FEV1/FVC ratio
• Reduced DLCO (often earliest abnormality)

Additional Testing

Echocardiography

• Assess for pulmonary hypertension
• Right ventricular function
• Estimate RVSP

Bronchoscopy/BAL

• If infection suspected
• Cytology for cell counts
• Rule out diffuse alveolar hemorrhage

Admission Criteria

ICU Admission

• Acute respiratory failure (SpO2 <88% on high-flow O2)
• Need for NIV or mechanical ventilation
• Hemodynamic instability
• Acute exacerbation of IPF
• Severe infection with respiratory compromise

Ward Admission

• New oxygen requirement
• Significant worsening from baseline
• Suspected infection requiring IV antibiotics
• Need for diagnostic workup
• Unable to manage at home

Discharge Criteria

• Stable oxygen requirements
• No signs of active infection
• Able to perform ADLs
• Adequate home support and oxygen equipment
• Follow-up arranged with pulmonology

Outpatient Follow-up

Understanding ILD

• ILD is a group of diseases affecting the lung tissue
• Causes the lungs to become stiff and makes breathing difficult
• Many causes exist; some are treatable, others managed symptomatically
• Regular follow-up and monitoring are essential

Oxygen Therapy

• Oxygen helps improve symptoms and may prolong life
• Use as prescribed (flow rate and duration)
• Safety precautions (no smoking, keep away from flames)
• Report worsening symptoms despite oxygen use

Medication Adherence

• Take medications exactly as prescribed
• Antifibrotics may cause GI side effects - take with food
• Do not stop steroids abruptly
• Report side effects promptly

Warning Signs to Return

• Worsening shortness of breath
• Fever or chills
• Change in cough or sputum
• Chest pain
• Swelling in legs or abdomen
• Confusion or altered mental status

Lifestyle Modifications

• Stop smoking (if applicable)
• Avoid exposures that trigger symptoms
• Pulmonary rehabilitation - improves function and quality of life
• Vaccinations - flu, pneumonia, COVID-19
• Advance care planning - discuss preferences with family and doctors

Elderly Patients

• IPF is predominantly a disease of older adults
• Higher complication rates from treatments
• Consider functional status and comorbidities
• Goals of care discussions essential
• Frailty affects transplant candidacy

Connective Tissue Disease-ILD

• Screen all CTD patients for lung involvement
• ILD may precede joint/skin manifestations
• Often NSIP pattern; may respond to immunosuppression
• Coordinate with rheumatology

Drug-Induced ILD

Common Culprits:

Management

• Discontinue offending agent
• Corticosteroids for moderate-severe
• May be reversible if caught early

Acute Interstitial Pneumonia (AIP)

• Rapidly progressive ILD (Hamman-Rich syndrome)
• Presents similar to ARDS without known cause
• Very high mortality (>50%)
• Treat with high-dose steroids
• Consider lung transplant if survivor

Performance Indicators

Documentation Requirements

• Baseline oxygen saturation and oxygen requirements
• Comparison to previous imaging/PFTs if available
• Suspected triggers for exacerbation
• Treatment initiated and response
• Disposition rationale
• Goals of care discussion (if applicable)
• Follow-up plan

Diagnostic Pearls

1. Velcro crackles at lung bases are classic for fibrotic ILD
2. Clubbing in a dyspneic patient strongly suggests ILD or lung cancer
3. HRCT is essential - CXR may be normal in early disease
4. UIP pattern on HRCT can diagnose IPF without biopsy
5. Always consider drug-induced ILD - review medication list carefully

Management Pearls

1. Target SpO2 88-92% - avoid both hypoxemia and hyperoxia
2. Pulse steroids for acute exacerbation even if infection suspected
3. Avoid triple therapy (steroids + azathioprine + NAC) in IPF
4. Antifibrotics slow decline but don't reverse fibrosis
5. Palliative care should be integrated early - symptom burden is high

Disposition Pearls

1. Acute exacerbation of IPF = ICU admission; high mortality
2. Do not delay intubation if needed, but discuss goals of care
3. Mechanical ventilation outcomes are poor in advanced ILD
4. Arrange close pulmonology follow-up for all discharged patients
5. Transplant evaluation should be considered early in appropriate candidates