Determination of leak and respiratory airflow
First Claim
1. In an apparatus with circuitry for airway treatment for a patient, a method for determining a degree of certainty that a leak has suddenly increased during airway treatment comprising the steps of:
- determining a measure of respiratory airflow to the patient;
determining an extent A to which the measure has been positive for longer than expected;
determining an extent B to which the measure is large and positive;
determining the degree of certainty that a leak has suddenly increased as a function of extent A and extent B.
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Accused Products
Abstract
Methods and apparatus for determining leak and respiratory airflow are disclosed. A pressure sensor (34) and a differential pressure sensor (32) have connection with a pneumotach (24) to derive instantaneous mask pressure and airflow respectively. A microcontroller (38) estimates a non-linear conductance of any leak path occurring at a mask (12) as being the low pass filtered instantaneous airflow divided by the low pass filtered square root of the instantaneous pressure. The instantaneous leak flow is then the conductance multipled by the square root of the instantaneous pressure, and the respiratory airflow is calculated as being the instantaneous airflow minus the instantaneous leak flow. The time constants for the low pass filtering performed by the microcontroller (38) can be dynamically adjusted dependent upon sudden changes in the instantaneous leak flow.
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Citations
30 Claims
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1. In an apparatus with circuitry for airway treatment for a patient, a method for determining a degree of certainty that a leak has suddenly increased during airway treatment comprising the steps of:
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determining a measure of respiratory airflow to the patient;
determining an extent A to which the measure has been positive for longer than expected;
determining an extent B to which the measure is large and positive;
determining the degree of certainty that a leak has suddenly increased as a function of extent A and extent B. - View Dependent Claims (2, 3, 4)
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5. In an apparatus with control circuitry for airway treatment for a patient, a method for determining a degree of certainty that a leak has suddenly decreased during airway treatment comprising the steps of:
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determining a measure of respiratory airflow to the patient;
determining an extent A to which the measure has been negative for longer than expected;
determining an extent B to which the measure is large and negative;
determining the degree of certainty that a leak has suddenly decreased as a function of extent A and extent B. - View Dependent Claims (6, 7, 8)
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9. In an apparatus with control circuitry for airway treatment for a patient, a method for determining an extent to which a leak has suddenly changed during airway treatment of a patient comprising the steps of:
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determining an increase-index of a degree of certainty to which the leak has suddenly increased;
determining a decrease-index of a degree of certainty to which the leak has suddenly decreased; and
determining the extent to which the leak has suddenly changed as a function of the increase-index and the decrease-index. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. An apparatus for determining a degree of certainty that a leak has suddenly increased during airway treatment of a patient comprising:
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means for delivering a controlled supply of pressure support to a patient'"'"'s airway;
means for determining a flow signal representative of respiratory airflow to the patient;
a control means in communication with the means for determining, the control means having programmed instructions for controlling a determination of a degree of certainty that a leak has suddenly increased, the instructions controlling steps comprising;
determining a measure of respiratory airflow to the patient from the flow signal;
determining an extent A to which the measure has been positive for longer than expected;
determining an extent B to which the measure is large and positive;
determining the degree of certainty that a leak has suddenly increased as a function of extent A and extent B. - View Dependent Claims (17, 18, 19)
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20. An apparatus for determining a degree of certainty that a leak has suddenly increased during airway treatment of a patient comprising:
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means for delivering a controlled supply of pressure support to a patient'"'"'s airway;
means for determining a flow signal representative of respiratory airflow to the patient;
a control means in communication with the means for determining, the control means having programmed instructions for controlling a determination of a degree of certainty that a leak has suddenly decreased, the instructions controlling steps of;
determining a measure of respiratory airflow to the patient from the flow signal;
determining an extent A to which the measure has been negative for longer than expected;
determining an extent B to which the measure is large and negative;
determining the degree of certainty that a leak has suddenly decreased as a function of extent A and extent B. - View Dependent Claims (21, 22, 23)
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24. An apparatus with coded control circuitry for airway treatment for a patient for determining an extent to which a leak has suddenly changed during airway treatment of a patient comprising:
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means for delivering a controlled supply of pressure support to a patient'"'"'s airway;
means for determining a flow signal representative of respiratory airflow to the patient;
a control means in communication with the means for determining, the control means having coded instructions for controlling a determination of a degree of certainty that a leak has suddenly changed, the instructions controlling steps comprising;
determining an increase-index of a degree of certainty to which the leak has suddenly increased;
determining a decrease-index of a degree of certainty to which the leak has suddenly decreased; and
determining the extent to which the leak has suddenly changed as a function of the increase-index and the decrease-index. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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Specification