Breathing gas delivery method and apparatus

• US 6,029,664 A
• Filed: 03/25/1997
• Issued: 02/29/2000
• Est. Priority Date: 09/22/1989
• Status: Expired due to Term

• Current Assignee: RIC INVESTMENTS LLC (Koninklijke Philips N.V.)
• Original Assignee: Respironics Incorporated (Koninklijke Philips N.V.)
• Inventors: Estes, Mark, Zdrojkowski, Ronald J.
• Primary Examiner(s): Lewis, Aaron J.
• Application Number:
  US08/823,855
• Time in Patent Office: 1,071 Days
• Field of Search: 128/204.23, 128/204.18, 128/204.21, 128/204.26, 128/202.22
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/026 specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: A61M 16/204 used for inhalation control
• CPC Class Codes: A61M 16/205 used for exhalation control
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/3561 local, e.g. within room or hospital

Abstract

A method of detecting changes in a person'"'"'s respiration between inspiration and expiration by monitoring of gas flow characteristics.

Claims

1. A method of detecting changes in a person'"'"'s respiratory state between inspiration and expiration comprising the steps of:

monitoring a respiratory gas flow of a person;

determining a value of a characteristic of said respiratory gas flow of such a person;

accumulating a plurality of said values of a characteristic of said respiratory gas flow;

identifying selected pairs of said plurality of values, wherein each pair of said plurality of values includes an earlier determined value and a later determined value;

processing said earlier determined value in at least some of said selected pairs;

comparing said selected pairs of said values; and

from said comparing, identifying changes in the person'"'"'s respiratory state between inspiration and expiration.

2. The method as set forth in claim 1, wherein said processing includes determining a fraction of said earlier determine value.

3. The method as set forth in claim 2, wherein said respiratory gas flow characteristic is a respiratory gas flow rate.

4. The method as set forth in claim 2, wherein said fraction corresponds to a predicted value of a respiratory gas flow rate at a selected time.

5. The method as set forth in claim 4, wherein said fraction is determined from an actual respiratory gas flow rate that occurred at a time prior to said selected time.

6. The method as set forth in claim, 4 wherein said respective later determined value in said selected pairs represent a person'"'"'s actual respiratory gas flow rate occurring at respective said selected times.

7. The method as set forth in claim 4, including an additional step of differentiating a function that defines a person'"'"'s respiratory gas flow rate to determine its derivative, and said processing includes processing said derivative and said function to determine said predicted value of such a person'"'"'s respiratory gas flow rate.

8. The method as set forth in claim 7, wherein said processing step includes scaling said derivatives with a scaling factor to obtain a scaled derivative.

9. The method as set forth in claim 8, wherein said processing step includes modifying said scaled derivative with an offset factor to determine said predicted value of such a person'"'"'s respiratory gas flow rate.

10. The method as set forth in claim 8, wherein said scaling factor includes a time factor.

11. The method as set forth in claim 10, wherein said time factor is determined at least in part by a time span between said selected time and a time prior to said selected time.

12. The method as set forth in claim 11, wherein said processing step includes modifying said scaled derivative with an offset factor to determine said predicted value of such a person'"'"'s respiratory gas flow rate.