title: Simulating respiratory loads and tuning of closed-circuit underwater breathing apparatus.
abstract: An experimental apparatus for simulating respiratory loads in closed-circuit underwater breathing systems comprises a partly submerged vertical tube having a dual path exit on the submerged end of the tube. One path is controlled by a valve that alters the inertance of the system, changes the natural frequency, and provides the tuning. The vertical tube provides elastic loading to simulate a counterlung or breathing bag in an underwater breathing apparatus (UBA). The experimental apparatus was connected to a breathing machine controlled by a signal generator to simulate a diver's breathing. The benefits of reactance tuning of this apparatus are demonstrated. A mathematical model describes both the simulator and UBA. The simulator can be used with human subjects to study respiratory response to changes in impedance.
authors.affiliation: Naval Medical Research Institute, Bethesda, Maryland 20889-5607, USA.
authors.forename: D D
authors.initials: DD
authors.lastname: Joye
authors.forename: P
authors.initials: P
authors.lastname: Wechgelaer
mesh_terms: D002138:Calibration; D004242:Diving / Q000502:physiology*; D004867:Equipment Design; D006801:Humans; D008954:Models, Biological; D008962:Models, Theoretical; D012119:Respiration / Q000502:physiology*; D014939:Work of Breathing