Breathing apparatus and method for operation thereof for examining pulmonary mechanics of a respiratory system

• US 6,709,405 B2
• Filed: 09/17/2002
• Issued: 03/23/2004
• Est. Priority Date: 09/25/2001
• Status: Expired due to Term

• Current Assignee: Maquet Critical Care AB (Getinge AB)
• Original Assignee: Siemens-Elema AB (Siemens AG)
• Inventors: Jonson, Björn
• Primary Examiner(s): Hindenburg, Max F.
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US10/245,898
• Publication Number:
  US 20030078512A1
• Time in Patent Office: 553 Days
• Field of Search: 600/538, 600/529, 600/531, 600/532, 600/533, 600/537, 128/200.24, 128/204.18, 128/204.21, 128/204.23, 128/204.26
• US Class Current: 600/538
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61M 16/0006 with means for creating vibrations in patients' airways
• CPC Class Codes: A61M 16/0051 with alarm devices
• 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 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 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2016/0042 in the expiratory circuit

Abstract

In an apparatus and method for examining the pulmonary mechanics of a respiratory system, in order to obtain information about the mechanical properties of the respiratory system'"'"'s lungs, during an expiration of a flow of gas streaming out of the respiratory system is modulated, the volume of gas streaming out of the respiratory system is determined, the variation in pressure in the respiratory system is determined, and an expiratory pressure-volume relationship is determined from the expiratory volume and the expiratory variation in pressure.

Claims

1. A method for examining pulmonary mechanics of a respiratory system, comprising the steps of:

modulating a flow of gas exiting a respiratory system during an expiration;

determining an expiratory volume of said gas exiting said respiratory system during said expiration;

determining an expiratory variation in pressure in said respiratory system during said expiration; and

determining an expiratory pressure-volume relationship from said expiratory volume and said expiratory variation in pressure.

2. A method as claimed in claim 1 comprising the additional steps of:

modulating a flow of gas entering into said respiratory system during an inspiration;

determining an inspiratory volume of said gas entering into said respiratory system during said inspiration;

determining an inspiratory variation in pressure in said respiratory system during said inspiration; and

determining an inspiratory pressure-volume relationship from said inspiratory volume and said insoiratory variation in pressure.

3. A method as claimed in claim 2 comprising prolonging a duration of said expiration immediately preceding said inspiration.

4. A method as claimed in claim 2 comprising the additional steps of:

comparing said inspiratory pressure-volume relationship with said expiratory pressure-volume relationship; and

determining a hysteresis between said inspiratory pressure-volume relationship and said expiratory pressure-relationship.

5. A method as claimed in claim 4 comprising determining said hysteresis by determining a difference in volume, for given values of pressure, between said inspiratory pressure-volume relationship and said expiratory pressure-volume relationship.

6. A method as claimed claim 4 comprising determining said hysteresis by determining a pressure gradient, for given values of volume, between said inspiratory pressure-volume relationship and said expiratory pressure-volume relationship.

7. A method as claimed in claim 4 comprising determining said hysteresis for a plurality of inspiratory pressure-volume relationships respectively compared with a plurality of expiratory pressure-volume relationships obtained over a plurality of respiratory cycles, each of said respiratory cycles having a different value of a selected parameter, and said selected parameter being selected, for each of said plurality of respiratory cycles, from the group consisting of positive end-expiratory pressure, peak inspiratory pressure, and tidal volume.

8. A breathing apparatus comprising:

a pneumatic unit adapted for communication with a respiratory system of a patient for regulating a flow and a pressure of gases into and out of respiratory system;

a sensor system for measuring said pressure and said flow and for generating a sensor system output dependent thereon;

a control unit connected to said pneumatic unit and to said sensor system, and

said control unit operating said pneumatic unit to modulate a flow of gas exiting a respiratory system during an expiration and, from said sensor system output, determining a volume of said gas exiting said respiratory system during said expiration, determining a variation in pressure in said respiratory system during said expiration, and determining an expiratory pressure-volume relationship from said expiratory volume and said expiratory variation in pressure.

9. A breathing apparatus as claimed in claim 8 wherein said control unit additionally:

operates said pneumatic unit to modulate a flow of gas entering into said respiratory system during an inspiration, and, from said sensor system output, determining a volume of said gas entering into said respiratory system during said inspiration, determining a variation in pressure in said respiratory system during said inspiration, and determining an inspiratory pressure-volume relationship from said inspiratory volume and said inspiratory variation in pressure.

10. A breathing apparatus as claimed in claim 9 wherein said control unit operates said pneumatic unit to prolong a duration of said expiration immediately preceding said inspiration.

11. A breathing apparatus as claimed in claim 9 wherein said control unit additionally compares said inspiratory pressure-volume relationship with said expiratory pressure-volume relationships, and determines a hysteresis between said inspiratory pressure-volume relationship and said expiratory pressure-relationship.

12. A breathing apparatus as claimed in claim 11 wherein said control unit determines said hysteresis by determining a difference in volume, for given values of pressure, between said inspiratory pressure-volume relationship and said expiratory pressure-volume relationship.

13. A breathing apparatus as claimed claim 11 wherein said control unit determines said hysteresis by determining a pressure gradient, for given values of volume, between said inspiratory pressure-volume relationship and said expiratory pressure-volume relationship.

14. A breathing apparatus as claimed in claim 11 wherein said control unit determines said hysteresis for a plurality of inspiratory pressure-volume relationships respectively compared with a plurality of expiratory pressure-volume relationships obtained over a plurality of respiratory cycles, each of said respiratory cycles having a different value of a selected parameter, and said selected parameter being selected, for each of said plurality of respiratory cycles, from the group consisting of positive end-expiratory pressure, peak inspiratory pressure, and title volume.

15. A breathing apparatus as claimed in claim 14 wherein said control unit automatically adapts said selected parameter dependent on said hysteresis.

16. A breathing apparatus as claimed in claim 8 further comprising an interface connected to said control unit for displaying a representation of at least said expiratory pressure-volume relationship.

17. A breathing apparatus as claimed in claim 16 wherein said user interface allows entry of parameters into said control unit.