Comparison of consistency, feasibility, and convenience of a novel compact system for assessing lung volumes and carbon monoxide diffusing capacity versus whole body plethysmography

Abstract

Background: The MiniBox+™ is an innovative technique for assessing lung volumes (LVs) and the diffusing capacity of the lung for carbon monoxide (DLco). Differently from the equipment needed for whole body plethysmography (WBP), the MiniBox+ is a small, transportable instrument, which derives total lung capacity (TLC) during tidal breathing by analyzing gas pressures and airflows immediately preceding and immediately following airway occlusions. Aim: To compare the consistency and the feasibility of LV and DLco measurements between the two instruments in different lung function disorders, and their cost of execution. Methods: Consecutive patients of both genders with obstructive and restrictive respiratory disorders were randomly recruited. LVs and DLco were measured by a randomized sequence. The failure risk, number of attempts to achieve the first reliable measurement, corresponding time spent, and costs per patient were compared. Results: A total of 134 patients were enrolled: 42 asthmatics (32.1%), and 47 patients with obstructive (35.1%) and 44 with restrictive respiratory disorders (32.8%). The overall failure risk was 19.4% for WBP and 8.2% for the MiniBox+ (risk ratio=0.417, 95% CI 0.242 to 0.72). LVs and DLco values proved equal with both techniques, regardless of the patients’ age, sex, schooling level, and initial lung disorder. Number of attempts and total time spent in achieving the first reliable measurement were significantly lower with the MiniBox+. Mean cost per patient was €87.58 with WBP and €75.11 with the MiniBox+, with a mean saving of €12.33 (95% CI 5.93 to 18.73), mainly due to the saving in productivity loss. Conclusion: LV and DLco measurements with the MiniBox+ were highly consistent with those obtained with WBP. The MiniBox+ proved easier to use (lower failure risk) and more convenient (lower execution costs) than WBP.