What are the next steps after an abnormal Pulmonary Function Test (PFT) result?

Next Steps After an Abnormal Pulmonary Function Test (PFT) Result

Following an abnormal pulmonary function test (PFT) result, the next steps should include a systematic evaluation based on the specific pattern of abnormality, additional diagnostic testing, and appropriate follow-up monitoring to guide treatment decisions and improve patient outcomes.

Interpreting the Abnormal PFT Result

• First, review the technical quality of the test to ensure proper technique was used and results meet acceptability and reproducibility criteria before making clinical decisions 1
• Compare patient results with predicted values based on age, sex, height, and ethnicity using appropriate reference equations 1
• Identify the specific pattern of abnormality:
  • Obstructive pattern: reduced FEV1/FVC ratio
  • Restrictive pattern: reduced FVC with normal or increased FEV1/FVC ratio
  • Mixed pattern: features of both obstruction and restriction
  • Diffusion abnormality: reduced DLCO 2

Immediate Follow-Up Testing

• For obstructive patterns:

  • Perform bronchodilator testing if not already done to assess reversibility 1
  • Consider complete PFT panel including static lung volumes and diffusion capacity (DLCO) to better characterize the abnormality 2

• For restrictive patterns:

  • Obtain lung volumes by plethysmography or washout technique to confirm true restriction 2
  • Measure diffusion capacity (DLCO) to evaluate gas exchange and assess severity 2

• For diffusion abnormalities:

  • Ensure DLCO is adjusted for hemoglobin and carboxyhemoglobin when monitoring for toxicity 1
  • Consider additional testing based on clinical context 2

Imaging Studies

• Obtain a chest CT scan when:
  • PFT shows obstructive pattern that persists over at least 2 weeks 2
  • There is clinical suspicion of interstitial lung disease with restrictive pattern 2
  • Evaluating for bronchiolitis obliterans syndrome (BOS) or other specific conditions 2
  • Consider inspiratory and expiratory views for better evaluation of air trapping 2

Additional Diagnostic Procedures

• Consider bronchoscopy with bronchoalveolar lavage (BAL) to:

  • Assess for infection when indicated 2
  • Evaluate for inflammatory or malignant conditions 2
  • Rule out other diagnoses when PFT patterns are unclear 2

• Lung biopsy may be indicated when:

  • The clinical picture is discordant with PFT and imaging findings
  • There is concern for an alternate or coexisting condition
  • A definitive diagnosis cannot be made by other means 2

Follow-Up Monitoring

• Frequency of follow-up PFTs should be based on:

  • Severity of the abnormality (mild, moderate, severe) 1
  • Underlying diagnosis or suspected condition 3
  • Presence of symptoms or disease progression 3

• For patients with established respiratory disease:

  • Test every 3 months until stability is demonstrated if there have been more than 2 hospitalizations in one year 3
  • Once stable, reduce frequency to every 6 months 3

• For specific conditions like post-HSCT surveillance:

  • First year: Every 3 months
  • Second year: Every 3-6 months
  • Third year: Every 6 months
  • Beyond 3 years: Annually 2

Disease-Specific Considerations

• For neuromuscular diseases:

  • Monitor PFTs at minimum every 6 months 3
  • Include vital capacity, maximum inspiratory and expiratory pressure, and peak cough flow 3

• For interstitial lung diseases:

  • Monitor every 3-6 months for the first year, then less frequently once stable 3
  • Pay particular attention to changes in DLCO, which may precede changes in spirometry 4

• For COPD:

  • Follow FEV1 as it correlates with symptom severity and prognosis 1
  • Monitor for accelerated decline that may require treatment adjustment 3

Common Pitfalls to Avoid

• Relying solely on computer interpretations without reviewing test quality 1
• Using FEV1/VC ratio to determine severity of obstruction instead of FEV1 % predicted 1
• Failing to measure lung volumes when a restrictive pattern is suspected based on spirometry alone 1
• Not recognizing that upper airway obstruction may be life-threatening despite being classified as only mildly reduced by FEV1 % predicted 1
• Overlooking that PFTs are only one tool and should be interpreted in clinical context 1, 5

Documentation and Communication

• Clearly document the pattern and severity of abnormality 2
• Compare with previous results to assess for significant changes over time 6
• Communicate findings to the patient and referring provider with specific recommendations for further evaluation or treatment 5