METHOD AND APPARATUS FOR MONITORING RESPIRATION

• US 20080214948A1
• Filed: 02/01/2008
• Published: 09/04/2008
• Est. Priority Date: 02/02/2007
• Status: Active Grant

• Current Assignee: Laerdal Medical AS (Laerdal Medical Corporation)
• Original Assignee: Laerdal Medical AS (Laerdal Medical Corporation)
• Inventors: Nysaether, Jon, Eilevstjonn, Joar, Myklebust, Helge
• Granted Patent: US 8,192,367 B2
• Time in Patent Office: Days
• US Class Current: 600/538
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/093 the gases being exhaled into, or inhaled from, an expansible chamber, e.g. bellows or expansible bag
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61M 16/0078 Breathing bags
• CPC Class Codes: A61M 16/0084 self-reinflatable by elasticity, e.g. resuscitation squeeze bags
• 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 16/0816 Joints or connectors
• CPC Class Codes: A61M 16/0858 Pressure sampling ports
• CPC Class Codes: A61M 16/0866 Passive resistors therefor
• CPC Class Codes: A61M 16/208 Non-controlled one-way valves, e.g. exhalation, check, pop-off non-rebreathing valves
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0042 in the expiratory circuit
• CPC Class Codes: A61M 2230/04 Heartbeat characteristics, e.g. ECG, blood pressure modulation
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/432 partial CO2 pressure (P-CO2)
• CPC Class Codes: A61M 2230/46 Resistance or compliance of the lungs
• CPC Class Codes: A61M 2230/65 Impedance, e.g. conductivity, capacity

Abstract

A device for monitoring respiration comprises a duct, a flow restricting element in the duct, and a pressure sensor arranged in the duct. The pressure sensor measures a pressure drop across the flow restricting element as a pressure difference between a pressure at a location in the duct on a first side of the flow restricting element and a substantially constant pressure on a second side of the flow restricting element opposite the first side.

Claims

1. A device for monitoring respiration, comprising:

a duct;

a flow restricting element in the duct; and

a pressure sensor arranged in the duct and operable to measure a pressure drop across the flow restricting element as a pressure difference between a pressure at a location in the duct on a first side of the flow restricting element and a substantially constant pressure on a second side of the flow restricting element opposite the first side.

2. The device of claim 1 wherein the duct is connected to a respiration device.

3. The device of claim 2 wherein the respiration device comprises one of a respiratory mask, a tracheal tube, and a bellow.

4. The device of claim 1 wherein the duct is integrated in a respiration device.

5. The device of claim 4 wherein the respiration device comprises one of a respiratory mask, a tracheal tube, and a bellow.

6. The device of claim 1 wherein the pressure sensor is arranged at the first side of the restriction.

7. The device of claim 1 wherein the restriction is shaped to ensure that the flow velocity is substantially equal on both sides of the restriction.

8. The device of claim 1 wherein the pressure sensor comprises an absolute pressure sensor.

9. The device of claim 1 wherein the pressure sensor comprises a differential pressure sensor.

10. The device of claim 1 wherein the substantially constant pressure is ambient pressure.

11. A device for monitoring respiration,

comprising:

a gas duct;

a restriction in the duct;

a one-way valve connected to the duct; and

a pressure sensor arranged in the duct and operable to measure a pressure drop across the restriction as a differential pressure between a pressure at a location in the duct on a first side of the restriction and a substantially constant pressure on a second side of the restriction.

12. The device of claim 11 wherein the one-way valve has known flow resistance.

13. The device of claim 11 wherein the pressure sensor is arranged at the first side of the restriction.

14. The device of claim 11 wherein the restriction is shaped to ensure that the flow velocity is substantially equal on both sides of the restriction.

15. The device of claim 11 wherein the substantially constant pressure is ambient pressure.

16. An apparatus for monitoring respiration,

comprising:

a duct having an obstruction therein;

a pressure sensor arranged in the duct and operable to measure a pressure difference between a pressure at a location in the duct on one side of the obstruction and a substantially constant pressure on the other side of the obstruction; and

a processing unit connected to the pressure sensor for processing the measured pressure signal.

17. The apparatus of claim 16, further comprising a user interface for providing information regarding the respiration to a user.

18. The apparatus of claim 16 wherein the processing unit is operable to calculate flow values from a linear relationship between pressure drop and flow.

19. The apparatus of claim 16 wherein the processing unit is operable to calculate respired volume.

20. The apparatus of claim 16 wherein the apparatus is connected to a CPR training manikin or simulator.

21. A method of monitoring respiration, comprising:

allowing a fluid to flow through a duct;

restricting the flow through the duct at a first location in the duct; and

measuring a pressure difference between a pressure at a second location in the duct and a substantially constant pressure at a third location in the duct, the first location being between the second and third locations.

22. The method of claim 21, further comprising determining at least one of volume flow and mass flow of the fluid based upon the measured pressure difference.

23. A method of measuring fluid flow, comprising:

flowing a fluid past an obstruction in a confined space; and

determining an amount of the fluid flow based upon a pressure drop from a first pressure at a location in the confined space upstream of the obstruction to a second pressure at a location in the confined space downstream of the obstruction, one of the first and second pressures being a substantially constant pressure.

24. The method of claim 23 wherein determining an amount of the fluid flow based upon a pressure drop comprises determining an amount of the fluid flow from a linear relationship between the pressure drop and the fluid flow.

25. The method of claim 23 wherein the substantially constant pressure is ambient pressure.