What is the initial step in lung function assessment for patients with bronchiectasis?

Lung Function Assessment in Bronchiectasis Workup

Spirometry to assess FEV1 and FVC is the initial step in lung function assessment for patients with bronchiectasis. 1, 2

Initial Lung Function Assessment

The European Respiratory Society (ERS) guidelines specifically recommend the following routine tests for lung function assessment in bronchiectasis:

1. Spirometry - Measuring FEV1 and FVC is the cornerstone of initial assessment 1

   • Should be performed when age-appropriate
   • Helps establish baseline lung function
   • Aids in monitoring disease progression

2. Pulse oximetry - To screen for respiratory failure 1, 2

3. Sputum collection - When patients can expectorate, for microbiological assessment 1

Patterns of Lung Function Impairment

Bronchiectasis presents with various patterns of lung function impairment that often overlap 3:

• Air trapping (70.2% of patients)
• Impaired diffusing capacity (55.7%)
• Airflow obstruction (41.1%)
• Hyperinflation (15.7%)
• Restriction (8.0%)

Only about 9.7% of patients have normal lung function 3, highlighting the importance of comprehensive assessment.

Advanced Lung Function Testing

After initial spirometry, consider:

• Body plethysmography - To assess air trapping and hyperinflation 3

  • Particularly useful as residual volume (RV) >120% predicted is common
  • Can detect reversibility in air trapping (RV reduction ≥10% from baseline)

• Diffusing capacity (DLCO) - To evaluate gas exchange 3, 4

  • Reduced DLCO is associated with more extensive disease (4 or more bronchiectatic lobes)

Monitoring Recommendations

• Perform spirometry every 3-6 months in outpatient clinics 1, 2
• Use lung function trends to:
  • Monitor disease progression
  • Detect complications
  • Assess treatment response
  • Identify exacerbations

Clinical Correlation

Lung function parameters correlate significantly with quality of life measures:

• FEV1 shows the strongest correlation with St. George's Respiratory Questionnaire scores (r = -0.873) 5
• Worse lung function is associated with:
  • Longer disease duration (≥10 years)
  • Pseudomonas aeruginosa colonization
  • Greater radiological extent of disease 4

Pitfalls and Caveats

1. Spirometry alone is insufficient - It does not capture the full spectrum of pathophysiological abnormalities in bronchiectasis 3

2. Bronchodilator reversibility - More commonly observed in residual volume (17.6%) than in FEV1 (4.3%), suggesting that standard reversibility testing may miss significant bronchodilator response 3

3. Exacerbation impact - During exacerbations, FVC and FEV1 show significant reductions, while other spirometric parameters show less notable changes 4

4. Radiological correlation - Significant lung function impairment should prompt evaluation for chest HRCT abnormalities 4

By starting with spirometry and pulse oximetry, clinicians can establish baseline lung function, identify the pattern of impairment, and develop an appropriate monitoring plan for patients with bronchiectasis.