Ventilator patient synchronization
First Claim
1. A method for determining a subject'"'"'s respiratory phase during ventilatory support comprising the steps of:
- identifying a plurality of phase states from a respiration cycle;
measuring airflow from a subject during the subject'"'"'s respiratory cycle;
calculating phase-state probabilities for said phase states with a measure of said airflow; and
determining a phase in the subject'"'"'s respiratory cycle from the calculated phase-state probabilities of said phase states.
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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
42 Claims
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1. A method for determining a subject'"'"'s respiratory phase during ventilatory support comprising the steps of:
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identifying a plurality of phase states from a respiration cycle;
measuring airflow from a subject during the subject'"'"'s respiratory cycle;
calculating phase-state probabilities for said phase states with a measure of said airflow; and
determining a phase in the subject'"'"'s respiratory cycle from the calculated phase-state probabilities of said phase states. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for determining a subject'"'"'s respiratory phase during ventilatory support comprising:
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a ventilator to provide a controlled supply of breathable gas to a subject'"'"'s airway;
a pressure transducer for generating an air flow signal representative of respiratory air flow from the subject; and
a processor with programmed instructions for controlling the steps of;
identifying a plurality of phase states of a respiration cycle;
determining a measure of air flow from said air flow signal;
calculating phase-state probabilities for said phase states with the measure of air flow; and
determining a phase in the subject'"'"'s respiratory cycle from the calculated phase-state probabilities of said phase states. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. An apparatus for determining a subject'"'"'s respiratory phase during ventilatory support 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 respiratory air flow from the patient; and
a control means with programmed instructions for controlling the steps of;
identifying a plurality of phase states of a respiration cycle;
determining a measure of air flow from said air flow signal;
calculating phase-state probabilities for said phase states with the measure of air flow; and
determining a phase in the subject'"'"'s respiratory cycle from the calculated phase-state probabilities of said phase states. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification