What are the indications and contraindications for Pulmonary Function Tests (PFTs)?

Indications and Contraindications for Pulmonary Function Tests (PFTs)

Pulmonary function tests should be performed for patients with respiratory symptoms, suspected or known pulmonary disease, and for monitoring disease progression, but should generally be avoided in patients with certain acute conditions or those who cannot perform the required maneuvers. 1

Indications for PFTs

Diagnostic Indications

• Evaluation of respiratory symptoms

  • Unexplained dyspnea, wheezing, or chronic cough 1
  • Assessment of respiratory symptoms in patients with known respiratory disease 1

• Suspected specific respiratory conditions

  • Obstructive lung diseases (asthma, COPD) 1
  • Restrictive lung diseases (interstitial lung disease, neuromuscular disorders) 1
  • Small airway disease 2

• Screening in high-risk populations

  • Systemic autoimmune rheumatic diseases (SARDs) with risk factors for interstitial lung disease 2
  • Baseline assessment in patients with Sjögren's syndrome (even if asymptomatic) 2
  • Idiopathic inflammatory myopathies 1

Monitoring Indications

• Disease progression monitoring

  • Systemic sclerosis-ILD: every 3-6 months in first year, then less frequently once stable 2
  • Rheumatoid arthritis-ILD: every 3-12 months in first year, then less frequently once stable 2
  • Neuromuscular diseases: every 6 months 1

• Treatment response evaluation

  • Assessment of response to bronchodilator therapy 1
  • Monitoring effects of disease-modifying treatments 1

Preoperative Evaluation

• Assessment of surgical risk for lung resection 3
• Preoperative evaluation for upper abdominal and cardiac surgeries 3

Contraindications for PFTs

Absolute Contraindications

• Recent myocardial infarction (within 1 week) 1
• Recent stroke or unstable cardiovascular status 1
• Thoracic, abdominal, or cerebral aneurysms at risk of rupture 1
• Recent eye surgery (risk of increased intraocular pressure) 1
• Hemoptysis of unknown origin (risk of worsening bleeding) 1
• Active tuberculosis or other serious transmissible respiratory infections 1

Relative Contraindications

• Chest or abdominal pain that would interfere with test performance 1
• Oral or facial pain exacerbated by mouthpiece 1
• Stress incontinence that would be worsened by forced maneuvers 1
• Dementia or confusion that prevents proper test performance 1
• Patients with decreased oral aperture (may need pediatric mouthpiece) 2

Special Considerations

Patient Factors Affecting Testing

• Age considerations

  • Elderly patients may have difficulty performing maneuvers 1
  • Children under 5 years typically cannot perform standard spirometry 1

• Physical limitations

  • Patients with systemic sclerosis may have difficulty achieving adequate oral seal (consider pediatric mouthpiece) 2
  • Patients with Raynaud's phenomenon require ear or forehead oxygen saturation monitoring instead of finger monitoring 2

Test Selection and Interpretation

• Complete PFTs should include:

  • Pre- and post-bronchodilator spirometry
  • Lung volumes
  • Diffusing capacity of the lung for carbon monoxide (DLCO) 2, 1

• Interpretation should consider:

  • Age, sex, height, and ethnicity when selecting reference values 1
  • Results expressed as z-scores rather than percentages 1
  • Comparison with previous results when available 1

When Not to Perform PFTs

• Asymptomatic screening

  • Routine screening in asymptomatic individuals without risk factors is not recommended 1
  • Asymptomatic children and adults with sickle cell disease should not undergo routine screening PFTs 2

• Monitoring limitations

  • Chest radiography is preferred over PFTs for monitoring SARD-ILD 2
  • Bronchoscopy with BAL should not be performed routinely in Sjögren's patients but determined case-by-case 2

Clinical Pearls and Pitfalls

• Common pitfalls

  • Failure to use appropriate reference values based on patient demographics 1
  • Not considering the clinical context when interpreting results 1
  • Over-reliance on a single parameter rather than evaluating the complete pattern 1

• Important considerations

  • Changes in FEV1 >12% and >200 mL are generally significant 1
  • Year-to-year changes in FEV1 should exceed 15% to be considered clinically meaningful 1
  • Trending multiple parameters (FEV1, FVC, DLCO) provides more comprehensive understanding of disease progression 1

By following these guidelines for PFT indications and contraindications, clinicians can appropriately utilize this valuable diagnostic tool while avoiding unnecessary testing or potential complications.