Abstract
We reasoned that the application of positive pressure through air stacking (AS) technique could cause gas compression and the absolute lung volumes could be estimated. The aim of this study was to estimate the amount of gas compression (ΔV comp) during AS in healthy subjects positioned at 45° trunk inclination and verify if the simultaneous measurements of chest wall volume changes (ΔV CW), by optoelectronic plethysmography, and changes in lung volume (ΔV ao), by pneumotachograph, combined with pressure variation at the airways opening (ΔP ao) during AS are able to provide reliable data on absolute lung volumes. Twenty healthy subjects (mean age 23.5±3.8years) were studied during a protocol that included slow vital capacity and AS maneuvers. V comp was calculated by subtracting ΔV ao and ΔV CW occurring during AS and total lung capacity (TLC) was estimated by applying Boyle-Mariote's law using V comp and ΔP ao. During AS, 0.140±0.050L of gas was compressed with an average ΔP ao of 21.78±6.18cmH2O. No significant differences between the estimated TLC (-0.03±3.0% difference, p=0.6020), estimated FRC (-2.0±12.4% difference, p=0.5172), measured IC (1.2±11.2% difference, p=0.7627) and predicted values were found. During AS, a significant gas compression occurs and absolute lung volumes can be estimated by simultaneous measurements of ΔV CW, ΔV ao and ΔP ao.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
