title: Use of an acoustic helium analyzer and microprocessor for rapid measurement of absolute lung volume during mechanical ventilation.
abstract: A technique developed to measure functional residual capacity during mechanical ventilation uses an acoustic helium analyzer and microprocessor to perform open-circuit helium washout. The acoustic helium analyzer has acceptable linearity up to a helium concentration of 50% and is stable. The microprocessor combines output from the acoustic analyzer and a ventilator with an expiratory flow signal, to compute lung volume rapidly during mechanical ventilation. In a sample of ten patients with various lung problems, open-circuit helium washout gave results similar to those of a closed-circuit helium-dilution technique during assist control or intermittent mandatory ventilation modes, with or without positive end-expiratory pressure. This open-circuit system has an advantage over other techniques because it is small and portable and can measure lung volume quickly without complicated maneuvers.
mesh_terms: D000162:Acoustics; D000328:Adult; D000368:Aged; D003201:Computers; D005652:Functional Residual Capacity; D006371:Helium / Q000032:analysis*; D006801:Humans; D008176:Lung Volume Measurements / Q000295:instrumentation* / Q000379:methods; D008838:Microcomputers; D008875:Middle Aged; D012121:Respiration, Artificial
chemical_list: D006371:Helium