Upper airway resistance measurement device

Patent metadata

Field	Value
Publication number	US-9895081-B2
Application number	US-201214345426-A
Country	US
Kind code	B2
Filing date	Sep 11, 2012
Priority date	Sep 21, 2011
Publication date	Feb 20, 2018
Grant date	Feb 20, 2018

Abstract

A method of estimating the upper airway resistance of a patient using a gas delivery system includes delivering a flow of breathing gas to the patient through the patient circuit of the gas delivery system, superimposing an oscillatory pressure on the flow of breathing gas during an expiratory phase of the patient, determining a first amplitude of an oscillatory component of a gas pressure provided to the patient at an end of the expiratory phase, determining a second amplitude of an oscillatory component of a gas flow provided to the patient at the end of the expiratory phase, determining a first resistance value based on the ratio of the first amplitude to the second amplitude, and determining an upper airway resistance value based on the first resistance value.

First claim

What is claimed is:

1. A method of treating a patient using a gas delivery system, comprising:
generating a flow of breathing gas using a pressure or flow generator of the gas delivery system;
delivering the flow of breathing gas to the patient through a patient circuit of the gas delivery system;
superimposing an oscillatory pressure on the flow of breathing gas delivered through the patient circuit using the pressure or flow generator during an expiratory phase of the patient;
generating a patient pressure signal using a pressure sensor of the gas delivery system during the expiratory phase, the patient pressure signal being indicative of a pressure provided to the patient through the patient circuit;
generating a patient flow signal using a flow sensor of the gas delivery system during the expiratory phase, the patient flow signal being indicative of a rate of gas flow provided to the patient through the patient circuit;
determining a first amplitude of an oscillatory component of a gas pressure provided to the patient at an end of the expiratory phase based on the patient pressure signal;
determining a second amplitude of an oscillatory component of a gas flow provided to the patient at the end of the expiratory phase based on the patient flow signal;
determining a first resistance value based on a ratio of the first amplitude to the second amplitude, wherein the first resistance value is an equivalent resistance value that represents a parallel combination of an upper airway resistance of the patient and a leak orifice resistance attributable to the patient circuit at the end of the expiratory phase;
determining an upper airway resistance value based on the first resistance value; and
using the upper airway resistance value to adjust a therapy pressure delivered to the patient by the gas delivery system as an airway patency of the patient changes during sleep.

2. The method according to claim 1 , wherein the determining an upper airway resistance value based on the first resistance value comprises determining the leak orifice resistance and determining the upper airway resistance value using the first resistance value and the leak orifice resistance.

3. The method according to claim 2 , wherein the determining the upper airway resistance value using the first resistance value and the leak orifice resistance is based on

R
lung

=

R
equiv

·

R
leak

R
leak

-

R
equiv

,

where R lung is the upper airway resistance value, R equiv is first resistance value and R leak is leak orifice resistance.

4. The method according to claim 1 , wherein a leak from the patient circuit is ignored and the upper airway resistance value is determined to be the first resistance value.

5. The method according to claim 1 , wherein the oscillatory pressure is an infrasonic wave.

6. A method of treating estimating an upper airway resistance of a patient using a gas delivery system, comprising:
generating a flow of breathing gas using a pressure or flow generator of the gas delivery system;
delivering the flow of breathing gas to the patient through a patient circuit of the gas delivery system;
superimposing an oscillatory pressure on the flow of breathing gas delivered through the patient circuit using the pressure or flow generator during an expiratory phase of the patient;
generating a patient pressure signal using a pressure sensor of the gas delivery system during the expiratory phase, the patient pressure signal being indicative of a pressure provided to the patient through the patient circuit,
generating a patient flow signal using a flow sensor of the gas delivery system during the expiratory phase, the patient flow signal being indicative of a rate of gas flow provided to the patient through the patient circuit;
determining a first amplitude of an oscillatory component of a gas pressure provided to the patient at an end of the expiratory phase based on the patient pressure signal, including performing a first root mean square calculation on data from the patient pressure signal corresponding to the end of the expiratory phase to calculate the first amplitude;
determining a second amplitude of an oscillatory component of a gas flow provided to the patient at the end of the expiratory phase based on the patient flow signal, including performing a second root mean square calculation on data from the patient flow signal corresponding to the end of the expiratory phase to calculate the second amplitude;
determining a first resistance value based on a ratio of the first amplitude to the second amplitude;
determining an upper airway resistance value based on the first resistance value;
using the upper airway resistance value to adjust a therapy pressure delivered to the patient by the gas delivery system as an airway patency of the patient changes during sleep.

7. The method according to claim 6 , wherein in the first root mean square calculation patient data from only a single cycle of the oscillatory pressure is used and wherein in the second root mean square calculation data from only the single cycle of the oscillatory pressure is used.

8. The method according to claim 6 , wherein the patient pressure signal is generated by the pressure sensor at an outlet of a pressure generating portion of the gas delivery system to which the patient circuit is coupled.

9. The method according to claim 6 , wherein the determining the first amplitude includes filtering the patient pressure signal, and wherein the determining the second amplitude includes filtering the patient flow signal.

10. A gas delivery system, comprising:
a pressure or flow generating system adapted to produce a flow of breathing gas;
a patient circuit operatively coupled to the pressure or flow generating system and structured to deliver the flow of breathing gas to the patient;
a pressure sensor;
a flow sensor; and
a controller operatively coupled to the pressure or flow generating system, the controller being structured and programmed to:
cause the pressure or flow generating system to generate the flow of breathing gas and superimpose an oscillatory pressure on the flow of breathing gas during an expiratory phase of the patient;
receive a patient pressure signal generated by the pressure sensor during the expiratory phase, the patient pressure signal being indicative of a pressure provided to the patient through the patient circuit;
receive a patient flow signal generated by the flow sensor during the expiratory phase, the patient flow signal being indicative of a rate of gas flow provided to the patient through the patient circuit;
determine a first amplitude of an oscillatory component of a gas pressure provided to the patient at an end of the expiratory phase based on the patient pressure signal;
determine a second amplitude of an oscillatory component of a gas flow provided to the patient at the end of the expiratory phase based on the patient flow signal;
determine a first resistance value base

Assignees

• Truschel William A
• Mahadevan Anandi
• Koninklijke Philips Nv

Inventors

• Truschel William A
• Mahadevan Anandi

Classifications

• A61M2016/0027

  pressure meter · CPC title

• A61M2016/0039

  in the inspiratory circuit · CPC title

• A61B5/085 Primary

  Measuring impedance of respiratory organs or lung elasticity · CPC title

• A61M16/0069

  the speed thereof being controlled by respiratory parameters, e.g. by inhalation · CPC title

• A61M2016/0042

  in the expiratory circuit · CPC title