J Appl Physiol (1985). 2024 Aug 8. doi: 10.1152/japplphysiol.00340.2024. Online ahead of print.
ABSTRACT
Multiple breath washout (MBW) has successfully assessed the silent lung zone particularly in cystic fibrosis lung disease, however, it is limited to the communicating lung only. There are a number of different pulmonary function methods that can assess what is commonly referred to as trapped air, with varying approaches and sensitivity. Twenty-five people with cystic fibrosis (pwCF) underwent MBW, spirometry, body plethysmography, and spirometry-controlled computed tomography (spiro-CT) on the same day. PwCF also performed extensions to MBW that evaluate air trapping, including our novel extension (MBWShX), which reveals the extent of under-ventilated lung units (UVLU). Additionally, we used 2 previously established 5-breath methods that provide a volume of trapped gas (VTG). We used trapped air % from spiro-CT as the gold standard for comparison. UVLU derived from MBWShX showed the best agreement with trapped air %, both in terms of correlation (RS 0.89, P<0.0001) and sensitivity (79%). Bland-Altman analysis demonstrated a significant underestimation of the VTG by both 5-breath methods (-249ml [95%CI -10796; 580ml] and -203ml [95%CI -997;591ml], respectively). Parameters from both spirometry and body plethysmography were sub-optimal at assessing this pathophysiology. The parameters from MBWShX demonstrated the best relationship with spiro-CT and had the best sensitivity compared to the other pulmonary function methods assessed in this study. MBWShX shows promise to assess and monitor this critical pathophysiological feature, which has been shown to be a driver of lung disease progression in pwCF.
PMID:39116346 | DOI:10.1152/japplphysiol.00340.2024
