METHODS AND SYSTEMS FOR MONITORING VOLUMETRIC CARBON DIOXIDE

• US 20130006133A1
• Filed: 06/30/2011
• Published: 01/03/2013
• Est. Priority Date: 06/30/2011
• Status: Abandoned Application

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Doyle, Peter R., Kimm, Gardner, Jafari, Mehdi M.
• Application Number:
  US13/174,130
• Publication Number:
  US 20130006133A1
• 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: A61M 16/0063 Compressors
• 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 16/0833 T- or Y-type connectors, e.g. Y-piece
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2016/103 the CO2 concentration
• CPC Class Codes: A61M 2205/502 User interfaces, e.g. screens or keyboards
• CPC Class Codes: A61M 2230/432 partial CO2 pressure (P-CO2)

Abstract

This disclosure describes novel systems and methods for monitoring volumetric CO₂ during ventilation of a patient being ventilated by a medical ventilator. The disclosure describes more accurate, more cost effective, and/or less burdensome non-invasive methods and systems for calculating volumetric CO₂ than previously utilized methods and systems. The disclosure describes estimating a flow rate in a breathing circuit to calculate a volumetric CO₂. Further, the disclosure describes synchronizing the estimated flow rate with a measured CO₂ to calculate a volumetric CO₂. Additionally, the disclosure describes synchronizing a measured flow rate from within the breathing circuit with a measured CO₂ to calculate a volumetric CO₂.

Claims

1. A method for monitoring volumetric CO₂ during ventilation of a patient being ventilated by a medical ventilator, the method comprising:

monitoring flow rate with at least one sensor at a first location within a breathing circuit;

monitoring CO₂ concentrations with a capnometer at a second location in the breathing circuit;

synchronizing at least one CO₂ measurement taken by the capnometer with at least one flow rate measurement taken by the at least one sensor from a same sampling period; and

calculating a volumetric CO₂ passing through at least one of the first and second locations for at least one breath based at least on an algorithm and the at least one CO₂ measurement synchronized with the at least one flow rate measurement.

2. The method of claim 1, wherein the at least one sensor is at least one of a flow sensor and a pressure sensor.

3. The method of claim 1, wherein the first location and the second location are the same location.

4. The method of claim 1, wherein the algorithm is

5. The method of claim 1, further comprising monitoring an amount of oxygen exhaled by the patient with an oxygen sensor at a third location in the breathing circuit.

6. The method of claim 5, wherein the step of synchronizing is at least based on at least one oxygen measurement taken by the oxygen sensor.

7. The method of claim 1, wherein the step of calculating the volumetric CO₂ for each breath based on the algorithm has an accuracy of at least 90%.

8. The method of claim 1, wherein the step of synchronizing comprises:

selecting a common event; and

aligning the at least one CO₂ measurement and the at least one flow rate measurement based at least on timing of the common event.

9. The method of claim 8, wherein the step of aligning further comprises utilizing the common event to determine a delay between the at least one CO₂ measurement and the at least one flow rate measurement.

10. The method of claim 9, wherein the step of aligning further comprises accounting for the delay to synchronize the at least one CO₂ measurement with the at least one flow rate measurement.

11. The method of claim 8, wherein the common event is at least one of a start of inspiration, a start of exhalation, and a transition point between inspiration and exhalation.

12. The method of claim 8, wherein the step of aligning is further based on at least one of inspiratory status, expiratory status, response time of ventilator delivery valves, response time of ventilator exhalation valves, compliance of the breathing circuit, and estimates of anatomic dead-space.

13. A medical ventilator system, comprising:

a pneumatic gas delivery system, the pneumatic gas delivery system adapted to control a flow of gas from a gas supply to a patient via a breathing circuit;

at least one sensor, the at least one sensor monitors flow rate at a first location in the breathing circuit;

a capnometer, the capnometer monitors an amount of carbon dioxide at a second location in the respiration gas in the breathing circuit;

a synchronization module, the synchronization module synchronizes at least one CO₂ measurement taken by the capnometer with at least one flow rate measurement taken by the at least one sensor from a same sampling period;

a processor in communication with the pneumatic gas delivery system, the at least one sensor, the capnometer, and the synchronization module, the processor is configured to calculate a volumetric CO₂ passing through at least one of the first and second locations for at least one breath based at least on an algorithm and the at least one CO₂ measurement synchronized with the at least one flow rate measurement.

14. The medical ventilator system of claim 13, wherein the at least one sensor is at least one of a flow sensor and a pressure sensor.

15. The medical ventilator system of claim 13, wherein the first location and the second location are the same location.

16. The medical ventilator system of claim 13, further comprising an oxygen sensor, the oxygen sensor monitors the amount of oxygen in the respiration gas at a third location in the breathing circuit.

17. The medical ventilator system of claim 16, wherein the synchronization module further synchronizes the at least one CO₂ measurement with the at least one flow rate measurement from the same sampling period based at least on at least one oxygen measurement taken by the oxygen sensor.

18. The medical ventilator system of claim 13, wherein the sampling period is determined by timing of a common event.

19. The medical ventilator system of claim 18, wherein the common event is at least one of a start of inspiration, a start of exhalation, and a transition point between inspiration and exhalation.

20. The medical ventilator system of claim 18, wherein the synchronization module synchronizes the at least one CO₂ measurement with the at least one flow rate measurement by accounting for any delay between the at least one CO₂ measurement taken by the capnometer and the at least one flow rate measurement taken by the at least one sensor based on the timing of the common event.

21. A computer-readable medium having computer-executable instructions for monitoring volumetric CO₂ during ventilation of a patient being ventilated by a medical ventilator, the method comprising:

repeatedly monitoring flow rate with at least one sensor at a first location within a breathing circuit;

repeatedly monitoring CO₂ concentrations with a capnometer at a second location in the breathing circuit;

repeatedly synchronizing at least one CO₂ measurement taken by the capnometer with at least one flow rate measurement taken by the at least one sensor from a same sampling period; and

repeatedly calculating a volumetric CO₂ passing through at least one of the first and second location for at least one breath based at least on an algorithm and the at least one CO₂ measurement synchronized with the at least one flow rate measurement.

22. A medical ventilator system, comprising:

means for monitoring flow rate with at least one sensor at a first location within a breathing circuit;

means for monitoring CO₂ concentrations with a capnometer at a second location in the breathing circuit;

means for synchronizing at least one CO₂ measurement taken by the capnometer with at least one flow rate measurement taken by the at least one sensor from a same sampling period; and

means for calculating a volumetric CO₂ passing through at least one of the first and second location for at least one breath based at least on an algorithm and the at least one CO₂ measurement synchronized with the at least one flow rate measurement.