Leak-compensated pressure triggering in medical ventilators
First Claim
1. A method of compensating for leakage in a ventilation system during delivery of gas from a medical ventilator to a patient comprising:
- estimating leakage from the ventilation system during delivery of gas to the patient based on measurements of at least one of pressure and flow;
modeling the leakage as a first leakage component through a first orifice of a fixed size and a second leakage component through a second orifice of a varying size, wherein the first and second leakage components are different functions of one or more of instantaneous pressure and instantaneous flow in the ventilation system;
estimating instantaneous lung flow of gas exhaled or inhaled by the patient during an exhalation phase;
identifying a target pressure trigger threshold indicative of patient inspiratory effort;
monitoring an instantaneous pressure at a location in the ventilation system based on one or more measurements of instantaneous pressure or instantaneous flow in the ventilation system;
generating a leak-compensated pressure trigger condition based on the monitored instantaneous pressure, the target pressure trigger threshold, the estimated instantaneous lung flow and the second leakage component; and
using the leak-compensated pressure trigger condition to determine when the patient has begun to initiate an inhalation.
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Accused Products
Abstract
This disclosure describes systems and methods for compensating for inelastic and elastic leaks in a ventilation system. The disclosure describes a model-based enhancement to conventional pressure triggering methodology that optimizes the timing and patient work of pressure triggering performance. The methods and systems described herein compensate for the additional effort a patient has to exert to generate the same amount of airway pressure drops compared to no leak condition. One method described includes calculating an elastic leakage and an inelastic leakage based on current measurements of pressure and flow in the ventilation system and then compensating a pressure threshold for the effects of the inelastic and elastic leaks in the system.
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Citations
23 Claims
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1. A method of compensating for leakage in a ventilation system during delivery of gas from a medical ventilator to a patient comprising:
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estimating leakage from the ventilation system during delivery of gas to the patient based on measurements of at least one of pressure and flow; modeling the leakage as a first leakage component through a first orifice of a fixed size and a second leakage component through a second orifice of a varying size, wherein the first and second leakage components are different functions of one or more of instantaneous pressure and instantaneous flow in the ventilation system; estimating instantaneous lung flow of gas exhaled or inhaled by the patient during an exhalation phase; identifying a target pressure trigger threshold indicative of patient inspiratory effort; monitoring an instantaneous pressure at a location in the ventilation system based on one or more measurements of instantaneous pressure or instantaneous flow in the ventilation system; generating a leak-compensated pressure trigger condition based on the monitored instantaneous pressure, the target pressure trigger threshold, the estimated instantaneous lung flow and the second leakage component; and using the leak-compensated pressure trigger condition to determine when the patient has begun to initiate an inhalation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of compensating for leakage in a ventilation system during delivery of gas from a medical ventilator to a patient comprising:
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identifying an inelastic leakage in the ventilation system as a first function of at least one of a pressure measurement and a flow measurement in the ventilation system; identifying an elastic leakage in the ventilation system as a second function of at least one of the pressure measurement and the flow measurement in the ventilation system; and determining that the patient is initiating an inspiration based on the inelastic leakage, the elastic leakage and the at least one of the pressure measurement and the flow measurement in the ventilation system. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A pressure support system comprising:
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a pressure generating system adapted to generate a flow of breathing gas; a ventilation system including a patient interface device; one or more sensors operatively coupled to the pressure generating system or the ventilation system, each sensor capable of generating an output indicative of a pressure of the breathing gas; a processor; an elastic leak estimation module that identifies an elastic leakage in the ventilation system; a compensation module that generates a leak-compensated pressure trigger condition based on the elastic leakage and at least one output indicative of a pressure of the breathing gas; and an inspiration detection module that determines when a patient has begun to inhale based on the leak-compensated pressure trigger condition and an output of at least one sensor. - View Dependent Claims (19, 20)
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21. A controller for a medical ventilator comprising:
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a microprocessor; and a pressure trigger compensation means for adjusting an initial pressure trigger threshold, based on; identifying an elastic leakage in a ventilation system as a first function of at least one of a pressure measurement and a flow measurement in the ventilation system; identifying an inelastic leakage in the ventilation system as a second function of at least one of the pressure measurement and the flow measurement in the ventilation system; and generating a leak-compensated pressure trigger condition based on the initial pressure trigger threshold, the inelastic leakage, the elastic leakage and at least one of the pressure measurement and the flow measurement in the ventilation system. - View Dependent Claims (22, 23)
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Specification