Carbon dioxide-sensing airway products and technique for using the same

• US 20080077034A1
• Filed: 09/25/2006
• Published: 03/27/2008
• Est. Priority Date: 09/25/2006
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Ostrowski, Rafael, O'Neil, Michael P., Mecca, Roger, Baker, Clark R.
• Granted Patent: US 8,128,574 B2
• Time in Patent Office: Days
• US Class Current: 600/532
• CPC Class Codes: A61B 5/0836 Measuring rate of CO2 production
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/091 Measuring volume of inspired or expired gases, e.g. to determine lung capacity
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61M 16/0057 Pumps therefor
• CPC Class Codes: A61M 16/04 Tracheal tubes catheters in general A61M25/00
• CPC Class Codes: A61M 16/0415 with access means to the stomach
• CPC Class Codes: A61M 16/042 with separate conduits for in-and expiration gas, e.g. for limited dead volume
• CPC Class Codes: A61M 16/0434 Cuffs
• CPC Class Codes: A61M 16/0443 Special cuff-wall materials A61M16/0481, A61M16/0422 take precedence
• CPC Class Codes: A61M 16/0459 one cuff behind another
• CPC Class Codes: A61M 16/0475 having openings in the tube
• CPC Class Codes: A61M 16/0486 Multi-lumen tracheal tubes
• CPC Class Codes: A61M 16/08 Bellows; Connecting tubes having means for taking samples G01N1/22; Water traps; Patient circuits
• CPC Class Codes: A61M 2016/0413 with detectors of CO2 in exhaled gases
• CPC Class Codes: A61M 2016/103 the CO2 concentration
• CPC Class Codes: A61M 2230/40 Respiratory characteristics
• CPC Class Codes: A61M 2230/432 partial CO2 pressure (P-CO2)

Abstract

An airway device is provided that may track the flow of respiratory gases through the device with sensing elements at a plurality of locations along the gas flow path of the device. Such a device may be useful for assessing a variety of clinical states, for adjusting patient ventilator settings, or for determining whether or not an airway device has been properly inserted into a patient airway.

Claims

1. A method of determining a change in a non-gas-exchanging physiologic volume in a ventilated patient comprising:

determining a concentration of carbon dioxide gas over time at a first location in a patient breathing circuit;

determining a concentration of carbon dioxide gas over time at a second location in the patient breathing circuit;

determining the transit time of the carbon dioxide gas between the two locations;

determining the volume of the breathing circuit between the first and second locations based on the cross-sectional area of the breathing circuit and the distance between the two locations; and

determining the flow rate over time of the carbon dioxide gas between the first location and the second location in the patient breathing circuit based on the determined volume and transit time, wherein a change in non-gas-exchanging physiologic volume is indicated by a change in the total volume exhaled while the carbon dioxide gas is increasing at the start of exhalation.

2. The method of claim 1, comprising determining from the change in the non-gas-exchanging physiologic volume that the patient has experienced a respiratory event.

3. The method of claim 1, comprising determining from the change in the non-gas-exchanging physiologic volume that the patient has experienced a lung trauma.

4. The method of claim 1, comprising determining from the change in the non-gas-exchanging physiologic volume that the patient has experienced a pulmonary embolism.

5. The method of claim 1, comprising triggering an indicator if the change in the non-gas-exchanging physiologic volume is beyond a critical threshold.

6. The method of claim 5, wherein the indicator comprises an alarm.

7. The method of claim 5, wherein the indicator comprises instructions related to a treatment protocol.

8. A computer readable medium with instructions for determining a change in a non-gas-exchanging physiologic volume in a ventilated patient comprising:

code for receiving signals from a plurality of carbon dioxide sensors disposed on a patient breathing circuit;

code for determining a concentration of carbon dioxide gas over time at a first location in a patient breathing circuit;

code for determining a concentration of carbon dioxide gas over time at a second location in the patient breathing circuit;

code for determining the transit time of the carbon dioxide gas between the two locations;

code for determining the volume of the breathing circuit between the first and second locations based on the cross-sectional area of the breathing circuit and the distance between the two locations; and

code for determining the flow rate over time of the carbon dioxide gas between the first location and the second location in the patient breathing circuit based on the determined volume and transit time, wherein a change in non-gas-exchanging physiologic volume is indicated by a change in the total volume exhaled while the carbon dioxide gas is increasing at the start of exhalation.

9. The computer readable medium of claim 8, comprising code for determining from the change in the non-gas-exchanging physiologic volume that the patient has experienced a respiratory event.

10. The computer readable medium of claim 8, comprising code for determining from the change in the non-gas-exchanging physiologic volume that the patient has experienced a pulmonary embolism.

11. The computer readable medium of claim 8, comprising code for triggering an indicator if the change in the non-gas-exchanging physiologic volume is beyond a critical threshold.

12. The computer readable medium of claim 11, wherein the indicator comprises an alarm.

13. The computer readable medium of claim 11, wherein the indicator comprises instructions related to a treatment protocol.

14. A medical system adapted to determine a change in a non-gas-exchanging physiologic volume in a ventilated patient comprising:

a processor adapted to;

receive signals from a plurality of carbon dioxide sensors disposed on a patient breathing circuit;

determine a concentration of carbon dioxide gas over time at a first location in a patient breathing circuit;

determine a concentration of carbon dioxide gas over time at a second location in the patient breathing circuit;

determine the transit time of the carbon dioxide gas between the two locations;

determine the volume of the breathing circuit between the first and second locations based on the cross-sectional area of the breathing circuit and the distance between the two locations; and

determine the flow rate over time of the carbon dioxide gas between the first location and the second location in the patient breathing circuit based on the determined volume and transit time, wherein a change in non-gas-exchanging physiologic volume is indicated by a change in the total volume exhaled while the carbon dioxide gas is increasing at the start of exhalation.

15. The medical system of claim 14, wherein the processor is adapted to determine from the change in the non-gas-exchanging physiologic volume that the patient has experienced a respiratory event.

16. The medical system of claim 14, wherein the processor is adapted to determine from the change in the non-gas-exchanging physiologic volume that the patient has experienced a pulmonary embolism.

17. The medical system of claim 14, wherein the processor is adapted to trigger an indicator if the change in the non-gas-exchanging physiologic volume is beyond a critical threshold.

18. The medical system of claim 17, wherein the indicator comprises an alarm.

19. The medical system of claim 18, wherein the alarm is an audio alarm or a visual alarm.

20. The medical system of claim 17, wherein the indicator comprises instructions related to a treatment protocol.