Bear Medical Systems, Inc.

Arieh S Halpern

James W Casparie

Ioan T Oltean

A ventilator control system is responsive to a flow rate signal from a flow rate sensor that senses the flow rate of gas to a ventilated patient. The ventilator control system provides an episode signal to a ventilator to actuate the ventilator to provide an assisted breath. The ventilator control system has an interactive control panel for providing an operator selectable duration signal scaled to define a selected time interval between breaths. An operator also selects a flow rate threshold signal scale to define the flow rate that must be exceeded to qualify a breath from a patient as a valid breath. Episode signal circuitry responds to the flow rate signal, the flow-rate threshold signal, and the duration signal to generate an episode signal in response to the flow rate signal failing to exceed the flow rate threshold signal within the selected time interval.

Ventilator control system using sensed inspiratory flow rate

A method for analyzing the concentration of selected constituent gases in the expiratory gas streams from a patient. The method includes the steps of: (a) measuring the flow rate of the expiratory gas stream to provide a flow rate signal; (b) generating a tidal volume signal in response to the flow rate signal; (c) generating a sample control signal in response to the tidal volume signal and the flow rate signal to mark an interval within the end tidal periods of several successive expiratory gas streams; (d) extracting a sample of each of the several successive expiratory gas streams during the marked interval in response to the sample control signal; (e) accumulating each extracted sample in a variable volume reservoir; (f) transferring the accumulated gas samples within the variable volume reservoir into a sample cell in response to the variable volume reaching a predetermined limit; and (g) measuring the concentration of the selected constituent gas in the volume of gas contained in the cell. The method optionally includes the further steps of (h) measuring the concentration of oxygen in an inspiratory gas stream conducted to the patient; and (i) calculating the patient's oxygen consumption by comparing the measured concentration of oxygen in the gas contained in the sample cell with the measured concentration of oxygen in the inspiratory gas stream.

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Riverside, CA, United States of America

Arieh S Halpern