Gas supply for sleep apnea

• US 6,814,074 B1
• Filed: 11/13/2001
• Issued: 11/09/2004
• Est. Priority Date: 05/21/1999
• Status: Expired due to Term

• Current Assignee: Covidien AG (Medtronic Plc)
• Original Assignee: Mallinckrodt Developpement France
• Inventors: Nicolazzi, Pascal, Nadjafizadeh, Hossein, Lanoir, Véronique Griller
• Primary Examiner(s): Bennett, Henry
• Assistant Examiner(s): Ragonese, Andrea M.
• Application Number:
  US09/913,237
• Time in Patent Office: 1,092 Days
• Field of Search: 128/204.18, 128/204.21, 128/204.22, 128/204.23
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/3344 Measuring or controlling pressure at the body treatment site

Abstract

Controlled pressurized air is supplied to the upper anatomical airways of a patient suffering from a sleep disorder, such as apnoea. The apparatus measures the air flow and pressure to the airway, and determines whether to increase or decrease the pressure based on a determination of several factors, such is the occurrence of hypopnoea, hyperventilation, air leakage and acoustical vibrations. The method of controlling the pressure includes determining a mean amplitude of the flow of air to the patient during a predetermined number of respiratory cycles. A hypopnoea time counter is incremented when the amplitude of the flow of air during a current respiratory cycle is less than the mean amplitude of the flow of air multiplied by a hypopnoea factor. The pressure of the flow of air to the patient is increased when the hypopnoea time counter is greater than or equal to a hypopnoea time threshold.

Claims

1. A method of controlling an apparatus for supplying air to an airway of a patient, comprising:

providing a flow of air at a pressure to a patient during a respiratory cycle of the patient;

determining the pressure of the flow of air during the respiratory cycle;

determining the flow of air during the respiratory cycle;

determining an amplitude of the flow of air during the respiratory cycle;

determining a mean amplitude of the flow of air to the patient during a predetermined number of respiratory cycles;

incrementing a hypopnoea time counter when the amplitude of the flow of air during a current respiratory cycle is less than the mean amplitude of the flow of air multiplied by a hypopnoea factor;

increasing the pressure of the flow of air to the patient by a first pressure increase value when the hypopnoea time counter is greater than or equal to a first hypopnoea time threshold;

after increasing the pressure of the flow of air to the patient, reducing the pressure of the flow of air to the patient by a first pressure reduction value when the pressure of the flow of air is less than a comparative pressure value; and

after increasing the pressure of the flow of air to the patient, reducing the pressure of the flow of air to the patient by a second pressure reduction value when the pressure of the flow of air is greater than or equal to the comparative pressure value.

2. The method according to claim 1, further comprising setting the second pressure reduction value greater than the first pressure reduction value.

3. The method according to claim 1, further comprising setting the first pressure reduction value to about −

0.5 mbar per five minutes, setting the second pressure reduction value to about −

0.5 mbar per one minute, and setting the comparative pressure value to between about four and about nineteen mbar.

4. The method according to claim 1, further comprising setting the predetermined number of respiratory cycles to about eight, setting the hypopnoea factor to between about one one-hundredths and about one, and setting the first hypopnoea time threshold to between about one second and about twenty-five seconds.

5. The method according to claim 1, further comprising:

after increasing the pressure of the flow of air to the patient by the first pressure increase value and after a first hypopnoea respiratory cycle threshold, increasing the pressure of the flow of air to the patient by a second pressure increase value; and

after increasing the pressure of the flow of air to the patient by the second pressure increase value and after a second hypopnoea respiratory cycle threshold, increasing the pressure of the flow of air to the patient by a third pressure increase value.

6. The method according to claim 5, further comprising:

setting the first hypopnoea time threshold to between about one second and about twenty-five seconds;

setting the first pressure increase value to about between about0.1 mbar and about ten mbar;

setting the first hypopnoea respiratory cycle threshold to about two cycles;

setting the second pressure increase value to about one-half the first pressure increase value;

setting the second hypopnoea respiratory cycle threshold to about four cycles; and

setting the third pressure increase value to about one-half the first pressure increase value.

7. The method according to claim 1, further comprising incrementing the hypopnoea time counter only when the mean amplitude of the flow of air is less than a first hyperventilation threshold.

8. The method according to claim 1, further comprising:

setting a high pressure time counter to zero when the pressure of the flow of air is less than a high pressure threshold;

incrementing the high pressure time counter when the pressure of the flow of air is not less than the high pressure threshold; and

reducing the pressure of the flow of air to a safety pressure value when the value of the high pressure time counter is greater than a maximum high pressure time threshold.

9. The method according to claim 8, further comprising setting the high pressure threshold to between about ten mbar and about twenty-five mbar, setting the maximum high pressure time threshold to between about one minute and about one-hundred minutes, and setting safety pressure value to about eight mbar.

10. The method according to claim 11, further comprising determining a leakage of the flow of air to the patient during the current respiratory cycle, and maintaining the pressure of the flow of air to the patient when the leakage of the flow of air is greater than a leakage level threshold.

11. The method according to claim 1, further comprising setting the leakage level threshold to substantially equal to an additive leakage value summed with a leakage coefficient multiplied by the pressure of the flow of air.

12. The method according to claim 11, further comprising setting the additive leakage value between about zero liters/minute and about one-hundred liters/minute, and setting the leakage coefficient between about zero liters/minute-mbar and about ten liters/minute-mbar.

13. The method according to claim 1, further comprising detecting oscillations of the flow of air to the patient, analyzing the detected oscillations so as to identify acoustic vibrations within an acoustic frequency range, and increasing the pressure of the flow of air to the patient when acoustic vibrations are identified.

14. The method according to claim 13, further comprising setting the acoustic frequency range to between about thirty hertz and about three-hundred hertz.

15. The method according to claim 1, further comprising storing a chronology of each detected hypoventilated cycle, and reading the stored chronology.

16. The method of controlling an apparatus for supplying air to a patient, comprising:

providing a flow of air at a pressure to a patient during a respiratory cycle of the patient;

determining the pressure of the flow of air during the respiratory cycle;

determining the flow of air during the respiratory cycle;

determining an amplitude of the flow of air during the respiratory cycle;

determining a leakage of flow of air to the patient during the respiratory cycle;

determining a mean amplitude of the flow of air to the patient during a predetermined number of respiratory cycles;

incrementing a hypopnoea time counter when the amplitude of the flow of air during a current respiratory cycle is less than the mean amplitude of the flow of air multiplied by a hypopnoea factor, when the mean amplitude of the flow of air is not greater than a first hyperventilation factor, and when the leakage of flow of air is not greater than a leakage level threshold;

setting a high pressure time counter to zero when the pressure of the flow of air is less than a high pressure threshold;

incrementing the high pressure time counter when the pressure of the flow of air is not less than the high pressure threshold;

increasing the pressure of the flow of air to the patient by a first pressure increase value when the hypopnoea time counter is greater than or equal to a first hypopnoea time threshold;

after increasing the pressure of the flow of air by the first pressure increase value and after a first hypopnoea respiratory cycle threshold, increasing the pressure of the flow of air by a second pressure increase value;

after increasing the pressure of the flow of air by the record pressure increase value and after a second hypopnoea respiratory cycle threshold, increasing the pressure of the flow of air by a third pressure increase value;

after increasing the pressure of the flow of air, reducing the pressure of the flow of air by a first pressure reduction value when the pressure of the flow of air is less than a comparative pressure value;

after increasing the pressure of the flow of air, reducing the pressure of the flow of air by a second pressure reduction value when the pressure of the flow of air is greater than or equal to the comparative pressure value; and

reducing the pressure of the flow of air to a safety pressure value when the value of the high pressure time counter is greater than at maximum high pressure time threshold.

17. An apparatus for supplying air under pressure to a patient, comprising:

means for providing a flow of air at a pressure to a patient during a respiratory cycle of the patient;

means for determining the pressure of the flow of air during the respiratory cycle;

means for determining the flow of air during the respiratory cycle;

means for determining an amplitude the flow of air during the respiratory cycle;

means for determining a mean amplitude of the flow of air to the patient during a predetermined number of respiratory cycles;

means for incrementing a hypopnoea time counter when the amplitude of the flow of air during a current respiratory cycle is less than the mean amplitude of the flow of air multiplied by a hypopnoea factor;

means for increasing the pressure of the flow of air to the patient by a first pressure increase value when the hypopnoea time counter is greater than or equal to a first hypopnoea time threshold;

means for reducing the pressure of the flow of air by a first pressure reduction value after increasing the pressure of the flow of air and when the pressure of the flow of air is less than a comparative pressure value; and

means for reducing the pressure of the flow of air by a second pressure reduction value after increasing the pressure of the flow of air and when the pressure of the flow of air is greater than or equal to the comparative pressure value.

18. The apparatus of claim 17, further comprising a detected event chronology memory.

19. The apparatus of claim 17, further comprising:

means for increasing the pressure of the flow of air by a second pressure increase value after increasing the pressure of the flow of air by the first pressure increase value and after a first hypopnoea respiratory cycle threshold; and

means for increasing the pressure of the flow of air by a third pressure increase value after increasing the pressure of the flow of air by the second pressure increase value and after a second hypopnoea respiratory cycle threshold.

20. The apparatus of claim 19, further comprising:

means for setting a high pressure time counter to zero when the pressure of the flow of air is less than a high pressure threshold;

means for incrementing the high pressure time counter when the pressure of the flow of air is not less than the high pressure threshold; and

means for reducing the pressure of the flow of air to a safety pressure value when the value of the high pressure time counter is greater than a maximum high pressure time threshold.