Abstract: A gas flow measuring system employs an oscillating chopper valve alternately to deliver a flow head-generated pressure and a reference pressure to a pressure transducer. The chopper valve is driven by a stepping motor under the control of a microcomputer. The stepping motor drives the valve, with an oscillatory frequency determined by the microcomputer, between a first detented position, in which the flow head-generated pressure is delivered to the transducer, and a second detented position, in which the reference pressure is delivered to the transducer. The electrical signal produced by the transducer is fed to a sample-and-hold circuit, also under the control of the microcomputer, whereby the microcomputer controls the sampling rate of the sample-and-hold circuit. The microcomputer can thus establish an optimal sampling rate in accordance with the oscillatory frequency of the valve. In this manner, very fast sampling rates can be established, thereby minimizing the effects of zero drift in the transducer.

Abstract: An aerosol interface comprises a housing defining a fluid receiving chamber in open communication with the atmosphere, with inlet means operatively associated with the housing for permitting continuous delivery to the chamber of a flow of an aerosol fluid so as to obtain an accumulation of the aerosol fluid therein for inhalation by a patient using the aerosol interface. Breath transmission means, operatively associated with the housing, has a passageway therethrough defined by an inner end and an outer end, the outer end being adapted for communication with the breath of a patient using the aerosol interface for the inhalation through the passageway of the aerosol fluid in the chamber and the exhalation of expired fluid by the patient into the passageway.

Abstract: A breath volume indicating system has a regulator controlling the flow of gas from a source of gas under pressure to a supply system delivering the gas under pressure to a patient as well as to a chamber providing a fixed volume to receive a supply of the gas. The regulator includes two valves respectively operatively associated with the supply system and the chamber, each valve being operable simultaneously between closed and open positions. In the closed position of the valves, generally coinciding with an inhalation period of the patient, the regulator provides a flow of the gas to the patient through the supply system and into the chamber, concurrently, and, in the open position, generally coinciding with the exhalation period of the patient venting of the supply system (and thereby the patient) and the chamber, concurrently.