Abstract
BackgroundAccurate estimates of multiple breath washout (MBW) outcomes require correct operation of the device, appropriate distraction of the subject to ensure they breathe in a manner representative of their relaxed tidal breathing pattern, and appropriate interpretation of the acquired data. Based on available recommendations for an acceptable MBW test, we aimed to develop a protocol to systematically evaluate MBW measurements based on these criteria.Methods50 MBW test occasions were systematically reviewed for technical elements and whether the breathing pattern was representative of relaxed tidal breathing by an experienced MBW operator. The impact of qualitative and quantitative criteria on inter-observer agreement was assessed across eight MBW operators (n = 20 test occasions, compared using a Kappa statistic).ResultsUsing qualitative criteria, 46/168 trials were rejected: 16.6% were technically unacceptable and 10.7% were excluded due to inappropriate breathing pattern. Reviewer agreement was good using qualitative criteria and further improved with quantitative criteria from (κ = 0.53–0.83%) to (κ 0.73–0.97%), but at the cost of exclusion of further test occasions in this retrospective data analysis.ConclusionsThe application of the systematic review improved inter-observer agreement but did not affect reported MBW outcomes.
Highlights
50 multiple breath washout (MBW) test occasions were systematically reviewed for technical elements and whether the breathing pattern was representative of relaxed tidal breathing by an experienced MBW operator
The lung clearance index (LCI), derived from the multiple breath inert gas washout (MBW) test, has been shown to be feasible across all ages and to detect early pathologic changes associated with obstructive lung disease.[1, 2]
While the MBW test requires minimal cooperation of the subject and is relatively easy to perform, accurate estimates of MBW outcomes rely on correct operation of the device, appropriate distraction of the subject to ensure they breathe in a manner representative of their relaxed tidal breathing pattern, and appropriate interpretation of the acquired data.[5]
Summary
The lung clearance index (LCI), derived from the multiple breath inert gas washout (MBW) test, has been shown to be feasible across all ages and to detect early pathologic changes associated with obstructive lung disease.[1, 2] The availability of commercial MBW devices provides an opportunity to use the LCI as an outcome measure in multi-center randomized control trial, as well as for the routine assessment of patients in the clinical setting.[3, 4] While the MBW test requires minimal cooperation of the subject and is relatively easy to perform, accurate estimates of MBW outcomes rely on correct operation of the device, appropriate distraction of the subject to ensure they breathe in a manner representative of their relaxed tidal breathing pattern, and appropriate interpretation of the acquired data.[5]The 2013 European Respiratory Society/American Thoracic Society (ERS/ATS) consensus statement for inert gas washout measurement provides general recommendations on test procedure and helps to standardize MBW devices and outcomes. The lung clearance index (LCI), derived from the multiple breath inert gas washout (MBW) test, has been shown to be feasible across all ages and to detect early pathologic changes associated with obstructive lung disease.[1, 2] The availability of commercial MBW devices provides an opportunity to use the LCI as an outcome measure in multi-center randomized control trial, as well as for the routine assessment of patients in the clinical setting.[3, 4] While the MBW test requires minimal cooperation of the subject and is relatively easy to perform, accurate estimates of MBW outcomes rely on correct operation of the device, appropriate distraction of the subject to ensure they breathe in a manner representative of their relaxed tidal breathing pattern, and appropriate interpretation of the acquired data.[5]. Accurate estimates of multiple breath washout (MBW) outcomes require correct operation of the device, appropriate distraction of the subject to ensure they breathe in a manner representative of their relaxed tidal breathing pattern, and appropriate interpretation of the acquired data. Based on available recommendations for an acceptable MBW test, we aimed to develop a protocol to systematically evaluate MBW measurements based on these criteria
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