Computerized measurement of pulmonary conductance and elastic recoil.
A system devloped for on-line measurement of transpulmonary pressure, gas flow at the mouth, change in expired volume and plethysmograph volume uses a minicomputer to control a multiplexed analog to digital converter. The computer identified samples as static or dynamic values by monitoring a voltage activating a solenoid valve, used to close the airway. Analysis of these samples by other task-specific programs yielded the static deflation pressure-volume (PV) curve, the conductance-recoil pressure, GL-Pst(L), relationship and the maximum expiratory flow-volume (MEFV) curve; the MEF-Pst(L) curve and conductance upstream from the equal pressure point were derived. The PV relationship was represented by a fourth-order polynomial and the GL-Pst(L) relationship by linear regression. In 11 subjects the results obtained using on-line data collection, compared with manual analysis of oscillograph recordings, showed small differences in static compliance and in the maximum Pst(L); but overall the two methods showed excellent agreement. Besides advantages of speed and objectivity, this system facilitates a more rigorous analytical treatment of elastic recoil and conductance.
D001249:Asthma / Q000503:physiopathology; D003201:Computers; D006801:Humans; D008168:Lung / Q000502:physiology / Q000503:physiopathology; D008170:Lung Compliance; D008176:Lung Volume Measurements / Q000295:instrumentation; D008449:Maximal Expiratory Flow-Volume Curves; D009862:Online Systems; D012129:Respiratory Function Tests / Q000295:instrumentation*; D014109:Total Lung Capacity