System and method for flow triggering of pressure supported ventilation by comparison of inhalation and exhalation flow rates
First Claim
1. A method of controlling flow of ventilation to a patient supplied with a preinspiratory, continuous flow of breathing gas from a ventilation system having a source of breathing gas, a patient breathing attachment, an exhalation valve, and a functionally open breathing gas flow path in fluid communication with said source of breathing gas, said ventilation flow path including at least one flow sensor located between said patient breathing attachment and said exhalation valve for measuring a flow rate of said breathing gas from said patient breathing attachment through said exhalation valve, the steps of the method comprising:
- delivering a predetermined rate of flow of said breathing gas from said source to said patient breathing attachment;
measuring said flow rate of breathing gas from said source of breathing gas to said patient breathing attachment to determine a gas supply flow rate;
measuring said flow rate of breathing gas from said patient breathing attachment through said exhalation valve at a location in said ventilation flow path between said breathing attachment and said exhalation valve to determine an exiting gas flow rate;
determining patient inspiratory effort in said flow path by comparing said gas supply flow rate with said exiting gas flow rate;
generating pressure support in said delivered flow of gas when said inspiratory effort exceeds a predetermined threshold value; and
restoring delivery of said breathing gas from said source to said patient breathing attachment at a preinspiratory, continuous rate of flow before a patient'"'"'s next inspiratory effort.
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Abstract
The system and method for flow triggering pressure supported ventilation include a source of a predetermined, preinspiratory, constant flow of breathing gas to a patient, one or more flow sensors for measuring the rate of gas flow in a flow path communicating with the patient, means for determining when inhalation from the flow path has occurred, and means for generating pressure support in the delivered gas flow in response to inhalation by the patient, means to terminate pressure support when inspiratory phase concludes, and means to reestablish the predetermined, preinspiratory, continuous flow of breathing prior to the patient'"'"'s next inspiratory effort. A plurality of individual gas sources preferably provide a controlled mixture of breathing gas. In combination with pressure support to the patient during the inspiration effort, the flow triggering strategy of the invention offers significant improvements in providing breath support to patients having weakened respiratory capabilities.
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Citations
11 Claims
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1. A method of controlling flow of ventilation to a patient supplied with a preinspiratory, continuous flow of breathing gas from a ventilation system having a source of breathing gas, a patient breathing attachment, an exhalation valve, and a functionally open breathing gas flow path in fluid communication with said source of breathing gas, said ventilation flow path including at least one flow sensor located between said patient breathing attachment and said exhalation valve for measuring a flow rate of said breathing gas from said patient breathing attachment through said exhalation valve, the steps of the method comprising:
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delivering a predetermined rate of flow of said breathing gas from said source to said patient breathing attachment; measuring said flow rate of breathing gas from said source of breathing gas to said patient breathing attachment to determine a gas supply flow rate; measuring said flow rate of breathing gas from said patient breathing attachment through said exhalation valve at a location in said ventilation flow path between said breathing attachment and said exhalation valve to determine an exiting gas flow rate; determining patient inspiratory effort in said flow path by comparing said gas supply flow rate with said exiting gas flow rate; generating pressure support in said delivered flow of gas when said inspiratory effort exceeds a predetermined threshold value; and restoring delivery of said breathing gas from said source to said patient breathing attachment at a preinspiratory, continuous rate of flow before a patient'"'"'s next inspiratory effort. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system for controlling flow of ventilation to a patient supplied with a preinspiratory, continuous flow of breathing gas from a ventilation system having a source of breathing gas, a patient breathing attachment, an exhalation valve, and a functionally open breathing gas flow path in fluid communication with said source of breathing gas, said patient breathing attachment and said exhalation valve, the system comprising:
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means for delivering said breathing gas from said source to said patient breathing attachment at said predetermined, continuous rate of flow; at least one flow sensor in said flow path for measuring the flow rate of said breathing gas from said source of breathing gas to said patient breathing attachment to determine a gas supply flow rate, and for measuring flow rate of said breathing gas from said patient breathing attachment through said exhalation valve at a location between said patient breathing attachment and said exhalation valve to determine an exiting gas flow rate; means responsive to said at least one flow sensor for determining patient breathing efforts by comparing said gas supply flow rate with said exiting gas flow rate to determine a flow rate change due to patient inhalation or exhalation; means for generating pressure support in said delivered flow of gas when said flow rate change exceeds a predetermined threshold value; and means for restoring delivery of said breathing gas from said source to said patient breathing attachment at said preinspiratory, continuous rate of flow before a next patient'"'"'s inspiratory effort. - View Dependent Claims (8, 9, 10, 11)
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Specification