Outcome measuring airway resistance diagnostic system

• US 6,210,345 B1
• Filed: 10/04/1999
• Issued: 04/03/2001
• Est. Priority Date: 10/04/1999
• Status: Expired due to Term

• Current Assignee: Hill-Rom Services Pte Ltd. (Baxter International Inc.)
• Original Assignee: American Biosystems, Inc (Baxter International Inc.)
• Inventors: Van Brunt, Nicholas P.
• Primary Examiner(s): Winakur, Eric F.
• Assistant Examiner(s): Natnithithadha, Navin
• Application Number:
  US09/412,086
• Time in Patent Office: 547 Days
• Field of Search: 600/529, 600/532, 600/538, 600/533
• US Class Current: 600/529
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61H 2205/08 Trunk
• CPC Class Codes: A61H 9/0078 with intermittent or alternately inflated bladders or cuffs mattresses for preventing bed-sores with alternated pressurized chambers A61G7/05776
• CPC Class Codes: A61M 16/0006 with means for creating vibrations in patients' airways
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation

Abstract

Airway resistance of a patient'"'"'s lungs is measured by applying an oscillating compressive force to the patient'"'"'s chest while supplying air pressure to a mouthpiece in communication with the patient'"'"'s mouth so that airflow from the patient'"'"'s mouth equals expiratory flow produced by the oscillating compressive force.

Claims

1. An airway resistance measurement method comprising:

applying an oscillating compressive force to a patient'"'"'s chest which includes a steady state force component and an oscillating force component;

supplying air pressure to a mouthpiece in communication with the patient'"'"'s mouth in a relationship to the oscillating compressive force; and

determining airway resistance based upon the compressive force applied to the patient'"'"'s chest and the air pressure supplied to the mouthpiece.

2. The method of claim 1 wherein supplying air pressure includes providing an oscillating air pressure component and a steady state air pressure component.

3. The method of claim 2 wherein the oscillating air pressure component is produced as a function of the oscillating force component.

4. The method of claim 3 wherein the oscillating air pressure component is produced with a phase relationship to the oscillating force component.

5. The method of claim 1 wherein the mouthpiece includes a mouthpiece chamber having a mouth port for communication with the patient'"'"'s mouth, an outlet port, and an air supply port through which the air pressure is supplied to the mouthpiece.

6. The method of claim 5 wherein air pressure is supplied to the air supply port of the mouthpiece to maintain a net average flow of air to the air supply port and out the outlet port.

7. The method of claim 1 wherein determining airway resistance comprises:

sensing air pressure at the mouthpiece;

sensing compressive force applied to the chest;

adjusting one of the compressive force and the air pressure so that outward air flow from the patient'"'"'s mouth essentially equals expiratory flow produced by the compressive force; and

providing an indication of airway resistance based upon the adjusting.

8. The method of claim 7 and further comprising:

providing an output based upon a first signal related to sensed air pressure and a second signal related to sensed compressive force, the output indicating a null condition when outward air flow essentially equals expiratory flow.

9. A method of measuring airway resistance of a patient'"'"'s lungs, the method comprising:

applying an oscillating compressive force to the patient'"'"'s chest;

supplying an oscillating air pressure to a mouthpiece in communication with the patient'"'"'s mouth;

sensing a null condition in which the oscillating compressive force and the oscillating air pressure produce an outward air flow from the patient'"'"'s mouth that essentially equals expiratory flow produced by the compressive force; and

providing a measurement of airway resistance based upon the sensed null condition.

10. An airway resistance measurement system comprising:

a chest wall force applicator for applying an oscillating compressive force to a patient'"'"'s chest;

a mouthpiece having a mouth port for positioning in the patient'"'"'s mouth, an outlet port for positioning outside the patient'"'"'s mouth, and an air supply port;

an air pressure supply connected to the air supply port;

a control system which controls operation of the chest wall force applicator and the air supply; and

an airway resistance indicator which provides an indication of airway resistance based on the oscillating compressive force and air pressure at the mouthpiece.

11. The system of claim 10 wherein the chest wall force applicator produces an oscillating compressive force having a steady state force component and an oscillatory force component.

12. The system of claim 11 wherein the air supply provides air to the air supply port according to an air pressure waveform having a steady state pressure component and on oscillatory pressure component.

13. The system of claim 12 wherein the control system causes the oscillatory pressure component to have a phase relationship to the oscillatory force.

14. The system of claim 12 wherein air is supplied to the air supply port of the mouthpiece to maintain a net average flow of air to the air supply port and out the outlet port.

15. The system of claim 10 and further comprising:

a sensor to measure air pressure at the mouthpiece; and

a sensor to measure the compressive force on the patient'"'"'s chest.

16. The system of claim 15 wherein the airway resistance indicator provides an indication of airway resistance based upon an adjustment of either the air pressure at the mouthpiece or the compressive force on the patient'"'"'s chest so that airflow from the patient'"'"'s mouth essentially equals expiratory flow produced by the compressive force.

17. The system of claim 10 wherein the airway resistance indicator senses a null point of pressure in which the oscillating compressive force and the oscillating air pressure produce an outward air flow from the patient'"'"'s mouth that essentially equals expiratory flow produced by the compressive force.

18. The system of claim 17 wherein the airway resistance indicator provides an indication of airway resistance based upon the null point of pressure.