Lung clearance index in patients with cystic fibrosis: Can we avoid repeating the test three times?

Multiple breath washout (MBW) testing and its derived measurements (e.g., lung clearance index (LCI)) are useful for measuring ventilation heterogeneity in patients with cystic fibrosis, monitoring disease progression, and assessing the response to treatments. However, the use of MBW in routine clinical practice is limited by the long washout time and total test duration, especially in patients with more advanced disease. Recommendations are to complete three MBW repeats. In this analysis, we examine whether two acceptable repeats would provide an accurate assessment of the LCI and could therefore avoid the need for a third measurement, thus reducing total test time.