Autotitrating method and apparatus

• US 7,882,834 B2
• Filed: 08/05/2005
• Issued: 02/08/2011
• Est. Priority Date: 08/06/2004
• Status: Active Grant

• Current Assignee: Fisher & Paykel Healthcare Limited
• Original Assignee: Fisher & Paykel Healthcare Limited
• Inventors: Whiting, David Robin, Anderson, Fiona Elizabeth, Gerred, Andrew Gordon, Smith, Gregory Martyn, Gradon, Lewis George
• Primary Examiner(s): Douglas; Steven O
• Assistant Examiner(s): Young; Rachel T
• Application Number:
  US11/198,072
• Publication Number:
  US 20060027234A1
• Time in Patent Office: 2,013 Days
• Field of Search: 128/204.21, 128/204.18, 128/204.23, 128/204.26, 128/200.24, 128/200.26, 128/204.29, 128/203.12, 128/204.22, 600/533
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/10 Preparation of respiratory gases or vapours
• CPC Class Codes: A61M 16/109 the humidifying liquid or the beneficial agent
• CPC Class Codes: A61M 16/16 Devices to humidify the respiration air A61M16/1045 takes precedence
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/003 with a flowmeter
• CPC Class Codes: A61M 2016/0033 electrical
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/3372 Temperature compensation

Abstract

An apparatus and method of controlling the delivery of therapeutic gas delivered to a patient undergoing positive airway pressure therapy is described. The method includes providing a flow of gas to a patient'"'"'s airway at a pressure, obtaining information from the range of 0 to 25 Hz of the frequency domain of the flow, and adjusting the pressure based on the information. The apparatus includes a blower for providing a flow of gas to a patient'"'"'s airway at a pressure, a sensor to measure a characteristic of the flow, a controller to obtain information from the range of 0 to 25 Hz of the frequency domain of the characteristic, and a pressure regulator for adjusting the pressure based on the information.

Claims

1. A method, of controlling positive airway pressure therapy, comprising the steps of:

providing a flow of gas to a patient'"'"'s airway at a supply pressure that does not include forced oscillation at a frequency greater than a breathing rate of a patient;

obtaining information comprising a discrete energy spectrum from a frequency range of 0 to 25 Hz in a frequency domain of said flow;

generating at least one information-bearing value from said frequency domain information, said information-bearing value comprising at least an energy in a first harmonic of said discrete energy spectrum and an energy in a second harmonic of said discrete energy spectrum; and

adjusting said pressure based on said information.

2. The method of claim 1, further comprising the steps of calculating a period of a breath of a patient and calculating an inspiratory portion of said period, and wherein said adjusting step comprises comparing said at least one information-bearing value to one of a plurality of thresholds, said one of a plurality of thresholds being selected according to a ratio of said inspiratory portion to said period.

3. A method of controlling positive airway pressure therapy, comprising the steps of:

providing a flow of gas to a patient'"'"'s airway at a supply pressure that does not include forced oscillation at a frequency greater than a breathing rate of a patient;

obtaining information comprising a discrete energy spectrum from a frequency range of 0 to 25 Hz in a frequency domain of said flow;

generating at least one information-bearing value from said frequency domain information, wherein said at least one information-bearing value comprises an energy in a first harmonic of said discrete energy spectrum, an energy in a second harmonic of said discrete energy spectrum, a sum of energies of said first harmonic through a thirteenth harmonic of said discrete energy spectrum, and a sum of energies of a fifth harmonic through said thirteenth harmonic of said discrete energy spectrum; and

adjusting said pressure based on said information.

4. The method of claim 3, further comprising the steps of calculating a period of a breath of a patient and calculating an inspiratory portion of said period, and wherein said adjusting step comprises comparing said at least one information-bearing value to one of a plurality of thresholds, said one of a plurality of thresholds being selected according to a ratio of said inspiratory portion to said period.

5. An apparatus for controlling positive airway pressure therapy, comprising:

a blower for providing a flow of gas to a patient at a pressure that does not include forced oscillation at a frequency greater than a breathing rate of a patient;

a sensor to measure a characteristic of said flow;

a controller to obtain information comprising a discrete energy spectrum from a frequency range of 0 to 25 Hz in a frequency domain of said characteristic and to generate at least one information-bearing value from said frequency domain information, wherein said at least one information-bearing value comprises at least an energy in a first harmonic of said discrete energy spectrum and an energy in a second harmonic of said discrete energy spectrum; and

a pressure regulator controlled by said controller for adjusting said pressure based on said information.

6. The apparatus of claim 5, wherein said controller further calculates a period of a breath of a patient and an inspiratory portion of said period, and further compares said at least one information-bearing value to one of a plurality of thresholds, said one of a plurality of thresholds being selected according to a ratio of said inspiratory portion to said period.

7. An apparatus for controlling positive airway pressure therapy, comprising:

a blower for providing a flow of gas to a patient at a pressure that does not include forced oscillation at a frequency greater than a breathing rate of a patient;

a sensor to measure a characteristic of said flow;

a controller to obtain information comprising a discrete energy spectrum from a frequency range of 0 to 25 Hz in a frequency domain of said characteristic and to generate at least one information-bearing value, wherein said at least one information-bearing value comprises an energy in a first harmonic of said discrete energy spectrum, an energy in a second harmonic of said discrete energy spectrum, a sum of energies of said first harmonic through a thirteenth harmonic of said discrete energy spectrum, and a sum of energies of a fifth harmonic through said thirteenth harmonic of said discrete energy spectrum.

8. The apparatus of claim 7, wherein said controller further calculates a period of a breath of a patient and an inspiratory portion of said period, and further compares said at least one information-bearing value to one of a plurality of thresholds, said one of a plurality of thresholds being selected according to a ratio of said inspiratory portion to said period.