Characterization of lung geometry from the single-breath nitrogen washout test

✍ Scribed by Lon Baker; James Ultman; Rodney Rhoades

• Book ID: 103051111
• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 729 KB
• Volume: 8
• Category: Article
• ISSN: 0010-4809
• DOI: 10.1016/0010-4809(75)90043-9

✦ Synopsis

A previously developed transport analysis was used to simulate two sets of singlebreath nitrogen washout data from each of four normal subjects. The analysis treats simultaneous gas flow and longitudinal diffusion and incorporates a modified form of Weibel's anatomical model "A" to describe the airway geometry. For each data set, four geometric parameters of the analysis were varied in a computer simulation until it matched the instantaneous expiratory concentration curve; particular emphasis was placed on matching the data in the concentration transition. Monitored values of functional residual capacity and instantaneous respiratory flow were supplied as inputs to each simulation.

For each subject, a reasonable computer simulation could be obtained using a single set of lower airway geometric parameters, even though the average respiratory flow rate varied by as much as 53 % from test to test: this result is due to the ability of the transport analysis to directly account for gas mixing during normal respiration. Under the same conditions the anatomic dead space varied by as much as 24 %.