Ventilator patient synchronization
First Claim
1. An apparatus for delivering ventilatory support to a subject synchronized to the subject'"'"'s respiratory phase, comprising:
- a means for providing a controlled supply of breathable gas to a subject'"'"'s airway;
a means for generating an air flow signal representative of the subject'"'"'s respiration; and
a processor to determine a phase of the subject'"'"'s respiratory cycle and to control the supply of breathable gas delivered to the subject'"'"'s airway;
wherein said processor determines a phase in the subject'"'"'s respiratory cycle by (a) designating a plurality of phase states within said subject'"'"'s respiratory cycle;
(b) calculating a measure of the subject'"'"'s respiration from said air flow signal;
(c) calculating a rate of change of the air flow signal from said measure of the subject'"'"'s respiration, (d) determining probabilities for said subject being in each of said phase states based on said rate of change; and
(e) identifying the phase in the subject'"'"'s respiratory cycle from the determined probabilities of said subject'"'"'s respiratory cycle being in each of said phase states; and
wherein said processor causes the delivery of a supply of breathable gas synchronized with the determined phase of the subject'"'"'s respiratory cycle.
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Accused Products
Abstract
A method and apparatus that provides an expert system for determining respiratory phase during ventilatory support of a subject. Discrete phase states are partitioned and prior probability functions and observed probability functions for each state are defined. The probability functions are based upon relative duration of each state as well as the flow characteristics of each state. These functions are combined to determine phase probabilities for each state using Bayes'"'"' theorem. The calculated probabilities for the states may then be compared to determine which state the subject is experiencing. A ventilator may then conform respiratory support in accordance with the most probable phase. To provide a learning feature, the probability functions may be adjusted during use to provide a more subject specific response that accounts for changing respiratory characteristics.
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Citations
26 Claims
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1. An apparatus for delivering ventilatory support to a subject synchronized to the subject'"'"'s respiratory phase, comprising:
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a means for providing a controlled supply of breathable gas to a subject'"'"'s airway; a means for generating an air flow signal representative of the subject'"'"'s respiration; and a processor to determine a phase of the subject'"'"'s respiratory cycle and to control the supply of breathable gas delivered to the subject'"'"'s airway; wherein said processor determines a phase in the subject'"'"'s respiratory cycle by (a) designating a plurality of phase states within said subject'"'"'s respiratory cycle;
(b) calculating a measure of the subject'"'"'s respiration from said air flow signal;
(c) calculating a rate of change of the air flow signal from said measure of the subject'"'"'s respiration, (d) determining probabilities for said subject being in each of said phase states based on said rate of change; and
(e) identifying the phase in the subject'"'"'s respiratory cycle from the determined probabilities of said subject'"'"'s respiratory cycle being in each of said phase states; andwherein said processor causes the delivery of a supply of breathable gas synchronized with the determined phase of the subject'"'"'s respiratory cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for delivering ventilatory support to a subject at a pressure synchronized with the subject'"'"'s respiratory phase, comprising:
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generating with a sensor an air flow signal representing said subject'"'"'s air flow; measuring with a processor the subject'"'"'s respiration from said air flow signal; calculating with the processor a rate of change of the subject'"'"'s respiration based on the subject'"'"'s measured respiration; designating with the processor a plurality of phase states within the subject'"'"'s respiratory cycle; determining with the processor probabilities for said subject'"'"'s respiratory cycle being in each of said phase states based on the rate of change of the subject'"'"'s respiration; identifying with the processor a phase in the subject'"'"'s respiratory cycle from the calculated probabilities of said phase states; and delivering a supply of breathable gas using a ventilator at a pressure synchronized with the determined phase of the subject'"'"'s respiratory cycle. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification