title: Characterization and measurement of elastance with application to underwater breathing apparatus.
abstract: The elastic loads inherent in underwater breathing apparatus (UBA) can affect diver performance. This work quantitatively examines elastance, its measurement by static tests, and its relationship to UBA. A rigid, fixed-volume container and a vertical water column with straight and parallel sides produce elastic loads that have application to closed-circuit UBA. We derived equations to describe the pressure-volume relationships of these elements from first principles and tested the equations experimentally for system pressure produced by a swept volume in a breathing machine. Our work demonstrates that simplified equations to describe elastance may not be sufficiently accurate for all situations. In addition, static measurements of elastance of a UBA or other element will not be reproducible unless all the volumes within the testing apparatus are accounted for; we provide experimental and mathematical techniques for doing so.
authors.affiliation: Diving Life Support Program, Naval Medical Research Institute, Bethesda, Maryland 20889-5607.
authors.forename: D D
authors.initials: DD
authors.lastname: Joye
authors.forename: J R
authors.initials: JR
authors.lastname: Clarke
authors.forename: N A
authors.initials: NA
authors.lastname: Carlson
authors.forename: E D
authors.initials: ED
authors.lastname: Thalmann
mesh_terms: D004242:Diving / Q000502:physiology; D004548:Elasticity; D006801:Humans; D011187:Posture / Q000502:physiology; D009626:Terminology as Topic; D014939:Work of Breathing