Using estimated carinal pressure for feedback control of carinal pressure during ventilation

• US 9,022,031 B2
• Filed: 01/31/2012
• Issued: 05/05/2015
• Est. Priority Date: 01/31/2012
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Nakai, Richard, Arul, Periagounder, Hyde, David
• Primary Examiner(s): Dixon, Annette
• Application Number:
  US13/362,085
• Publication Number:
  US 20130192599A1
• Time in Patent Office: 1,190 Days
• Field of Search: 128/200.24, 128/204.18, 128/204.21, 128/204.23, 128/202.16, 128/203.12, 128/202.22, 128/204.22, 128/205.24, 128/205.25, 128/204.29, 128/204.24, 128/205.23, 128/903, 128/898, 600/300, 600/301, 600/323, 600/324, 600/365, 600/529, 600/538, 715/77, 715/780, 715/716, 715/781, 702/51, 702/22, 340/500, 340/611, 340/614, 340/626, 340/679, 340/286.07, 340/539.12, 340/573.1, 324/426, 320/118, 320/124, 320/125, 320/132, 320/134, 320/426, 434/308, 345/1.2
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/0051 with alarm devices
• 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 16/161 with means for measuring the humidity
• 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 2016/102 Measuring a parameter of the content of the delivered gas
• CPC Class Codes: A61M 2205/505 Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: A61M 2230/43 Composition of exhalation

Abstract

This disclosure describes systems and methods for configuring a ventilator to estimate the carinal pressure to minimize the work of breathing due to a breathing tube. A patient'"'"'s carina is a cartilaginous ridge located at the site of the tracheal bifurcation between the two primary bronchi. An estimated carinal pressure (a pressure estimated to exist at the patient carina) may be determined and used as feedback control for the carinal pressure. According to embodiments, the estimated carinal pressure may be compared to the carinal pressure command to determine an error. The carinal pressure command may be positive end expiratory pressure (PEEP) or some other suitable target pressure. The error between the estimated carinal pressure and the carinal pressure command may then be used as feedback control to achieve the carinal pressure command and thereby to minimize the work of breathing due to the breathing tube.

Claims

1. A ventilator-implemented method for controlling delivery of gas flow to a patient, the method comprising:

delivering gas flow to the patient based on a carinal pressure command;

receiving a signal representative of a pressure at a patient wye;

calculating a pressure drop across a breathing tube extending from the patient wye to about the carina of the patient;

estimating a carinal pressure by subtracting the pressure drop across the breathing tube from the pressure at the patient wye;

comparing the estimated carinal pressure to the carinal pressure command; and

controlling delivery of gas flow to the patient based on comparing the estimated carinal pressure and the carinal pressure command.

2. The method of claim 1, wherein the pressure drop is estimated as a function of at least one of:

a gas flow through the breathing tube, atmospheric pressure, humidity, a gas composition, and a target inspiratory pressure.

3. The method of claim 1, wherein controlling delivery of gas flow to the patient further comprises:

determining an error based on comparing the estimated carinal pressure and the carinal pressure command; and

modulating the delivery of gas flow based on the error.

4. The method of claim 3, wherein the delivery of gas flow is adjusted based on the error when the estimated carinal pressure is less than the carinal pressure command.

5. The method of claim 3, wherein the delivery of gas flow is adjusted based on the error when the estimated carinal pressure is greater than the carinal pressure command.

6. The method of claim 1, wherein the signal representative of the pressure at the patient wye represents an estimated pressure at the patient wye.

7. The method of claim 1, wherein the carinal pressure command is one of:

positive end expiratory pressure (PEEP), a percentage of PEEP, and PEEP adjusted by an offset.

8. A ventilator system for controlling delivery of gas flow to a patient, the ventilator system comprising:

at least one processor; and

at least one memory communicatively coupled to the at least one processor and containing instructions that, when executed by the at least one processor, cause the ventilator system to;

deliver gas flow to the patient based on a carinal pressure command;

receive a signal representative of a pressure at a patient wye;

calculate a pressure drop across a breathing tube extending from the patient wye to about the carina of the patient;

estimate a carinal pressure by subtracting the pressure drop across the breathing tube from the pressure at the patient wye;

compare the estimated carinal pressure to the carinal pressure command; and

control delivery of gas flow to the patient based on comparing the estimated carinal pressure and the carinal pressure command.

9. The ventilator system of claim 8, wherein the pressure drop is estimated as a function of at least one of:

a gas flow through the breathing tube, atmospheric pressure, humidity, a gas composition, and a target inspiratory pressure.

10. The ventilator system of claim 8, wherein controlling delivery of gas flow to the patient further comprises:

determining an error based on comparing the estimated carinal pressure and the carinal pressure command; and

modulating the delivery of gas flow based on the error.

11. The ventilator system of claim 10, wherein the delivery of gas flow is adjusted based on the error when the estimated carinal pressure is less than the carinal pressure command.

12. The ventilator system of claim 10, wherein the delivery of gas flow is adjusted based on the error when the estimated carinal pressure is greater than the carinal pressure command.

13. The ventilator system of claim 8, wherein the signal representative of the pressure at the patient wye represents an estimated pressure at the patient wye.

14. The ventilator system of claim 8, wherein the carinal pressure command is one of:

positive end expiratory pressure (PEEP), a percentage of PEEP, and PEEP adjusted by an offset.

15. A ventilator processing interface for controlling delivery of gas flow to a patient, the ventilator processing interface comprising:

means for delivering gas flow to the patient based on a carinal pressure command;

means for receiving a signal representative of a pressure at a patient wye;

means for calculating a pressure drop across a breathing tube extending from the patient wye to about the carina of the patient;

means for estimating a carinal pressure by subtracting the pressure drop across the breathing tube from the pressure at the patient wye;

means for comparing the estimated carinal pressure to the carinal pressure command; and

means for controlling delivery of gas flow to the patient based on comparing the estimated carinal pressure and the carinal pressure command.

16. The ventilator processing interface of claim 15, wherein the controlling means for delivery of gas flow to the patient further comprises:

means for determining an error based on the comparison of the estimated carinal pressure and the carinal pressure command; and

means for modulating the delivery of gas flow based on the error.

17. The ventilator processing interface of claim 15, wherein the signal representative of the pressure at the patient wye represents an estimated pressure at the patient wye.

18. The ventilator processing interface of claim 15, wherein the carinal pressure command is one of positive end expiratory pressure (PEEP), a percentage of PEEP, and PEEP adjusted by an offset.

19. A non-transitory computer storage medium having computer-executable instructions that when executed by a processor cause a ventilator system to:

deliver gas flow to the patient based on a carinal pressure command;

receive a signal representative of a pressure at a patient wye;

calculate a pressure drop across a breathing tube extending from the patient wye to about the carina of the patient;

estimate a carinal pressure by subtracting the pressure drop across the breathing tube from the pressure at the patient wye;

compare the estimated carinal pressure to the carinal pressure command; and

control delivery of gas flow to the patient based on comparing the estimated carinal pressure and the carinal pressure command.

20. The non-transitory computer storage medium of claim 19, wherein controlling delivery of gas flow to the patient further comprises:

determining an error based on comparing the estimated carinal pressure and the carinal pressure command; and

modulating the delivery of gas flow based on the error.