Multiple breath washout: measuring early manifestations of lung pathology

Abstract

The multiple breath washout (MBW) test measures the efficiency of gas mixing in the lungs and has gained significant interest over the past 20 years. MBW outcomes detect early lung function impairment and peripheral airway pathology, through its main outcome measure lung clearance index (LCI). LCI measures the number of lung turnovers required to washout an inert tracer gas. MBW is performed during normal (tidal) breathing, making it particularly suitable for young children or those who have trouble performing forced manoeuvres. Additionally, research in chronic respiratory disease populations has shown that MBW can detect acute clinically relevant changes before conventional lung function tests, such as spirometry, thus enabling early intervention. The development of technical standards for MBW and commercial devices have allowed MBW to be implemented in clinical research and potentially routine clinical practice. Although studies have summarised clinimetric properties of MBW indices, additional research is required to establish the clinical utility of MBW and, if possible, shorten testing time. Sensitive, feasible measures of early lung function decline will play an important role in early intervention for people living with respiratory diseases.Educational aimTo describe the multiple breath washout test, its applications to lung pathology and respiratory disease, as well as directions for future research.

Lung Function Tests in Infants and Children

“…It is generally used in children with cystic fibrosis but is now increasingly used in obstructive diseases, bronchiectasis, and post-transplant bronchiolitis obliterans. The results are reported as lung clearance index (LCI) [ 39 ]. LCI indicates the number of lung turnovers needed to wash out the gas from the lungs.…”

Respiratory Follow Up of the Premature Neonates—Rationale and Practical Issues

“…Two processes occur simultaneously during this phase: the formation of the alveoli and the tethering of the airways [ 82 , 83 ]. The abnormal formation of the alveoli and the deficient tethering of the airways result in airway dysfunction and the risk of lung infections [ 82 , 83 ] There is an immune deficit at the level of the T lymphocytes, a deficient pulmonary cytotoxic lymphocyte response, leading to the attempt to clean the infection by the macrophages and neutrophils [ 84 ]. The infection is resolved, but this results in the damage to epithelial cells and abnormal activation of the Th2 lymphocytes, increasing the risk of recurrent wheezing and asthma [ 82 , 84 ].…”

Lung clearance index in children with cystic fibrosis previously diagnosed with CRMS/CFSPID: A monocentric prospective experience

“…[13][14][15][16] Multiple-breath washout (MBW) of inert tracer gases is known to be a noninvasive, sensitive, and feasible measure of lung function to detect peripheral airway changes in childhood. 17 The lung clearance index (LCI) measures the homogeneity of the pulmonary periphery derived from MBW. 17,18 The test entails monitoring an inert gas washed out from the lungs and only requires relaxed tidal breathing.…”

“…17 The lung clearance index (LCI) measures the homogeneity of the pulmonary periphery derived from MBW. 17,18 The test entails monitoring an inert gas washed out from the lungs and only requires relaxed tidal breathing. Previous cross-sectional studies in school-age children with CF have suggested that LCI is more sensitive than Forced Expiratory Volume in 1 s (FEV 1 ) for detecting early lung disease.…”