Sidestream Gas Sampling System with Closed Sample Circuit

• US 20080041172A1
• Filed: 06/29/2007
• Published: 02/21/2008
• Est. Priority Date: 07/06/2006
• Status: Active Grant

• Current Assignee: Philips RS North America LLC (Koninklijke Philips N.V.)
• Original Assignee: RIC INVESTMENTS LLC (Respironics Incorporated)
• Inventors: Jaffe, Michael, Rich, David
• Granted Patent: US 7,748,280 B2
• Time in Patent Office: Days
• US Class Current: 73/863.83
• CPC Class Codes: A61B 5/082 Evaluation by breath analysis, e.g. determination of the chemical composition of exhaled breath A61B5/083, A61B5/091 take precedence
• CPC Class Codes: A61B 5/097 Devices for facilitating collection of breath or for directing breath into or through measuring devices
• CPC Class Codes: G01N 1/2247 Sampling from a flowing stream of gas
• CPC Class Codes: G01N 1/24 Suction devices G01N1/22 - G01N1/2294 take precedence
• CPC Class Codes: G01N 2001/2244 Exhaled gas, e.g. alcohol detecting

Abstract

The invention provides a sidestream gas sampling apparatus having a gas sampling circuit and a set of reusable elements. The gas sampling circuit carries the gas sample from a main flow of gas, through a sample analysis area, and vents the gas sample to an analyzed gas destination. The reusable components provide motive forces to remove the gas sample through the gas sampling circuit and provide analysis components for the gas sampling apparatus while not making contact with the gas sample. As such, the reusable components do not become contaminated by the gas sample and do not have to be cleaned or sterilized between applications.

Claims

1. A sidestream gas sampling system, comprising:

(a) a first assembly adapted to communicate a gas sample from a gas sampling site to a gas measuring site, the first assembly including components that contact the gas sample during use, wherein the first assembly comprises;

(1) a sample transport tube that receives a gas sample from the gas sample site, and

(2) a sample analyzer region in which a characteristic of one or more components within the gas sample is measured; and

(b) a second assembly that is external to the first assembly at all times during use such that all components of the second assembly do not contact the gas sample, wherein the second assembly comprises;

(1) a pump operatively coupled to the sample transport tube to move the gas sample through the sample transport tube to the sample analyzer region without making contact with the gas sample.

(2) a flow measurement device that obtains information regarding a flow of the gas sample through the sample transport tube without making contact with the gas sample;

(3) a pressure measurement device that obtains information regarding a pressure of the gas sample within the sample transport tube without making contact with the gas sample;

or

(4) any combination of the pump, the flow measurement device, and the pressure measurement device.

2. The system of claim 1, wherein the sample transport tube includes at least one prong adapted to communicate with an airway of a patient.

3. The system of claim 1, wherein the sample transport tube and the sample analyzer region are defined as a unitary component.

4. The system of claim 1, wherein the first assembly further comprises:

(a) an adapter adapted to couple the sample transport tube to a patient circuit;

(b) a filter operatively coupled to the sample transport tube, the sample analyzer region, or both;

(c) a moisture removal system operatively coupled to the sample transport tube, the sample analyzer region, or both, wherein the moisture removal system is adapted to remove moisture from the gas sample;

or

(d) any combination of the adapter, the filter, and the moisture removal system.

5. The system of claim 1, wherein the flow measurement device comprises one of an optical flowmeter, a vortex shedding flowmeter, an ultrasonic flowmeter, or a thermal mass flowmeter.

6. The system of claim 1, wherein the pump comprises one or more of a diaphragm pump, a peristaltic pump, a Venturi vacuum pump, and an electroactive polymer actuated pump.

7. The system of claim 1, wherein the sample analyzer region comprises:

(a) a sample cell having at least two optical analysis windows;

(b) at least two optical analysis windows integrated into the sample transport tube;

(c) one or more electrical contacts that permit physical communication with a solid-state gas sensor or a surface acoustic wave sensor;

or

(d) any combination of (a), (b), and (c).

8. A method for measuring a concentration of one or more components of a gas sample taken from a mainstream flow of gas, the method comprising:

(a) providing a first assembly adapted to communicate a gas sample from a gas sampling site to a gas measuring site, the first assembly including components that contact the gas sample during use;

(b) providing a second assembly that is external to the first assembly at all times during use such that all components of the second assembly do not contact the gas sample;

(c) coupling the first assembly to the second assembly;

(d) carrying a gas sample from a gas sample site using a first component of the first assembly;

(d) using a first component of the second assembly to;

(1) obtaining flow information regarding a flow of the gas sample without making contact with the gas sample using the second assembly,

(2) obtaining pressure information regarding a pressure of the gas sample without making contact with the gas sample using the second assembly, or

(3) obtaining both the flow information and the pressure information using the second assembly;

(e) measuring a characteristic of one or more components within the gas sample using a second component of the second assembly.

9. The method of claim 8, further comprising using a second component of the second assembly to move the gas sample through the first component of the first assembly.

10. The method of claim 8, further comprising:

decoupling the coupling the first assembly to the second assembly after a first measuring process is complete;

disposing the first assembly; and

reusing the second assembly with another first assembly in a second measuring process.

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

obtaining flow information regarding a flow of the gas sample without making contact with the gas sample using the second assembly;

obtaining pressure information regarding a pressure of the gas sample without making contact with the gas sample using the second assembly;

or

obtaining both the flow information and the pressure information using the second assembly.

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

filtering the gas sample using the first assembly;

dehumidifying the gas sample using the first assembly;

or both filtering and dehumidifying the gas sample using the first assembly.

13. A sidestream gas sampling apparatus, comprising:

(a) a gas sampling circuit comprising;

(1) a sample transport tube that receives a gas sample from a mainstream flow of gas, and

(2) a sample analyzer region in which a characteristic of one or more components within the gas sample is measured; and

(b) a pump that creates a pressure differential within the gas sampling circuit to remove the gas sample from the mainstream flow of gas and move the gas sample through the sample transport tube to the sample analyzer region without making contact with the gas sample.

14. The apparatus of claim 13, further comprising:

(a) a flow measurement device that obtains information regarding a flow of the gas sample through the gas sampling circuit without making contact with the gas sample;

(b) a pressure measurement device that obtains information regarding a pressure of the gas sample within the gas sampling circuit without making contact with the gas sample;

or

(c) both the flow measurement device and the pressure measurement device

15. The apparatus of claim 14, wherein information regarding the flow of the gas sample through the gas sampling circuit is utilized to control the pump to ensure a constant flow of gas through the gas sampling circuit.

16. The apparatus of claim 14, wherein the flow measurement device comprises one of an optical flowmeter, a vortex shedding flowmeter, an ultrasonic flowmeter, or a thermal mass flowmeter.

17. The apparatus of claim 14, wherein the pressure measurement device measures the deformity of a diaphragm integrated into the sample transport tube to measure the pressure within the gas sampling circuit.

18. The apparatus of claim 14, wherein the information regarding the pressure of the gas sample within the gas sampling circuit is utilized to account for effects the pressure has on the measurement of the characteristic of the one or more components within the gas sample.

19. The apparatus of claim 13, wherein the characteristic of the one or more components within the gas sample comprises:

(a) one or more of a concentration of the one or more components within the gas sample and a partial pressure of the one or more components within the gas sample comprises the concentration;

or

(b) one or more components within the gas sample expressed as one or more of a percentage, parts per million (ppm), and parts per billion (ppb).

20. The apparatus of claim 13, wherein the characteristic of the one or more components within the gas sample is measured using spectroscopy, infrared spectroscopy, luminescence quenching, a solid-state gas sensor, a surface acoustic wave (SAW) sensor, or any combination thereof.

21. The apparatus of claim 13, wherein the sample analyzer region comprises:

(a) a sample cell having at least two optical analysis windows;

(b) at least two optical analysis windows integrated into the sample transport tube;

(c) one or more electrical contacts that permit physical communication with the solid-state gas sensor or the surface acoustic wave sensor;

or

(d) any combination of (a), (b), and (c).

22. The apparatus of claim 13, wherein the sample analyzer region comprises at least two optical analysis windows.

23. The apparatus of claim 13, wherein the one or more components whose characteristic within the gas sample is measured is one or more of carbon dioxide (CO₂), carbon monoxide (CO), oxygen (O₂), nitric oxide (NO), and anesthetic agents.

24. The apparatus of claim 13, wherein the pump comprises one or more of a diaphragm pump, a peristaltic pump, a Venturi vacuum pump, and an electroactive polymer actuated pump.

25. The apparatus of claim 13, wherein the gas sampling circuit further comprises a sample exhaust port that expels the gas sample from the gas sampling circuit after it has passed through the sample analyzer region.

26. The apparatus of claim 25, wherein the sample exhaust port (a) returns the gas sample to the mainstream flow of gas, or (b) transports the gas sample to a disposal apparatus.

27. The apparatus of claim 13, wherein the sample transport tube comprises first and second lumens, wherein the first lumen carries the gas sample towards the sample analyzer region, and wherein the second lumen carries the gas sample away from the sample analyzer region.

28. The apparatus of claim 13, wherein the sample transport tube includes a moisture removal region that removes moisture from the gas sample.

29. The apparatus of claim 28, wherein the moisture removal region comprises a section of hydrophilic tubing, a dehumidifying material, a water trap, or any combination thereof.

30. The apparatus of claim 13, further comprising an adapter that removes the gas sample from the mainstream flow of gas and introduces the gas sample into the gas sampling circuit.

31. A method for measuring a concentration of one or more components of a gas sample taken from a mainstream flow of gas, the method comprising:

removing a gas sample from a mainstream flow of gas;

transporting the gas sample to a sample analyzer region via a sample transport tube;

measuring a characteristic of the one or more components within the gas sample in the sample analyzer region; and

pumping the gas sample through the sample transport tube using a pump mechanism that does not contact the gas sample.

32. The method according to claim 31, further comprising replacing the sample transport tube for use with the same pump mechanism.

33. The method according to claim 31, further comprising:

(a) obtaining flow information regarding a flow of the gas sample without making contact with the gas sample;

(b) obtaining pressure information regarding a pressure of the gas sample without making contact with the gas sample;

or

(c) obtaining both the flow information and the pressure information.