Ventilator control system using sensed inspiratory flow rate
First Claim
1. A method of controlling a time-cycled constant-flow, pressure-limited medical ventilator during the ventilation of a patient, wherein the ventilator has a selectable breath rate interval, the method comprising the steps of:
- (a) sensing the inspiratory flow rate of the patient and generating a flow rate signal;
(b) selecting a flow rate threshold value;
(c) selecting an episode time interval;
(d) selecting a number of ventilator-delivered breaths;
(e) comparing the flow rate signal value to the selected flow rate threshold value during the selected episode time; and
(f) actuating the ventilator to deliver the selected number of ventilator-delivered breaths to the patient if the flow rate signal value remains below the selected flow rate threshold value throughout the duration of the selected episode time interval.
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Accused Products
Abstract
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.
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Citations
18 Claims
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1. A method of controlling a time-cycled constant-flow, pressure-limited medical ventilator during the ventilation of a patient, wherein the ventilator has a selectable breath rate interval, the method comprising the steps of:
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(a) sensing the inspiratory flow rate of the patient and generating a flow rate signal; (b) selecting a flow rate threshold value; (c) selecting an episode time interval; (d) selecting a number of ventilator-delivered breaths; (e) comparing the flow rate signal value to the selected flow rate threshold value during the selected episode time; and (f) actuating the ventilator to deliver the selected number of ventilator-delivered breaths to the patient if the flow rate signal value remains below the selected flow rate threshold value throughout the duration of the selected episode time interval. - View Dependent Claims (2, 3, 4)
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5. A respiratory ventilator system for controllably ventilating a patient, wherein the system includes a time-cycled, constant-flow, pressure-limited ventilator operable in a mandatory ventilation mode with a selectable breath rate interval, and in a CPAP mode, the ventilator having an inspiratory flow line, an expiratory flow line, and a patient connector for coupling the inspiratory and expiratory flow lines to a patient, wherein the improvement comprises:
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flow rate sensing means, in the patient connector, for generating a flow rate signal indicative of the flow rate of gas inspired by the patient through the connector; and a ventilator control device, receptive to the flow rate signal and operatively coupled to the ventilator, the ventilator control device comprising; first control means for providing a selectable duration signal scaled to define a selected time interval; second control means for providing a selectable flow rate threshold signal; episode signal generation means, responsive to the flow rate signal, the duration signal, and the flow rate threshold signal, for generating an episode signal in response to the failure of the flow rate signal to attain the value of the flow rate threshold signal within the selected time interval; and ventilator actuation means, responsive to the episode signal, for actuating the ventilator to deliver a breath to the patient each time the episode signal is generated, independently of the selected breath rate interval of the ventilator, when the selected time interval is shorter than the selected breath rate interval of the ventilator operated in the mandatory ventilation mode. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A respiratory ventilator system for controllably ventilating a patient, wherein the system includes a time-cycled, constant-flow, pressure-limited ventilator operable in a mandatory ventilation mode with a selectable breath rate interval, and in a CPAP mode, the ventilator having an inspiratory flow line, an expiratory flow line, and a patient connector for coupling the inspiratory and expiratory flow lines to a patient, wherein the improvement comprises:
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first means for fluidly coupling the ventilator to a patient; second means in the first means for sensing an inspiratory effort by the patient and generating a flow rate signal in response thereto; and a ventilator control device, operatively coupled to the ventilator, the ventilator control device comprising; third means for providing a threshold signal having a selectable value; fourth means for providing a selectable episode time interval; fifth means for providing a selectable number of ventilator-delivered breaths when the ventilator is operated in the CPAP mode; sixth means responsive to the flow rate signal and the threshold signal, for generating an episode signal when the value of the flow rate signal remains below the selected threshold signal value for the duration of the selected episode time interval; and seventh means for actuating the ventilator, when operated in the CPAP mode, to deliver the selected number of ventilator-delivered breaths in response to each episode signal. - View Dependent Claims (16, 17, 18)
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Specification