METHODS AND SYSTEMS FOR ADAPTIVE BASE FLOW

• US 20130146055A1
• Filed: 12/07/2011
• Published: 06/13/2013
• Est. Priority Date: 12/07/2011
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: Jafari, Mehdi M., Masic, Milenko, Aviano, Jeffrey K., McCoy, Edward R., Jimenez, Rhomere S.
• Granted Patent: US 9,364,624 B2
• Time in Patent Office: Days
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/0057 Pumps therefor
• 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 16/04 Tracheal tubes catheters in general A61M25/00
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: A61M 16/0833 T- or Y-type connectors, e.g. Y-piece
• CPC Class Codes: A61M 16/0875 Connecting tubes
• CPC Class Codes: A61M 2016/0015 inhalation detectors
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2016/0042 in the expiratory circuit
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2205/505 Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: A61M 2230/40 Respiratory characteristics

Abstract

This disclosure describes systems and methods for providing novel adaptive base flow scheduling during ventilation of a patient to optimize the accuracy of estimated exhaled tidal volume. Further, this disclosure describes systems and methods for providing novel adaptive inspiratory trigger threshold scheduling during the novel adaptive base flow scheduling.

Claims

1. A method for ventilating a patient with a ventilator, comprising:

determining an initial base flow;

determining an initial inspiration trigger threshold;

delivering the initial base flow during at least a first portion of exhalation while setting the inspiration trigger threshold to the initial inspiration trigger threshold;

determining a desired base flow;

determining a desired inspiration trigger threshold;

increasing base flow from the initial base flow toward the desired base flow during at least a second portion of exhalation; and

decreasing the inspiration trigger threshold from the initial inspiration trigger threshold toward the desired inspiration trigger threshold based on a function of the step of increasing the base flow while performing the step of increasing the base flow.

2. The method of claim 1, wherein the step of increasing the base flow includes increasing the base flow at a first exponential trajectory, and

wherein the step of decreasing the inspiration trigger threshold includes decreasing the inspiration trigger threshold at a second exponential trajectory.

3. The method of claim 1, wherein the initial base flow is zero.

4. The method of claim 1, wherein the second portion of exhalation begins based on an occurrence of a condition, the condition being at least one of a group including:

determining that a minimum exhalation time has expired;

determining that an exhalation flow is below a minimum exhalation flow;

determining that the exhalation flow is below the minimum exhalation flow prior to expiration of a maximum exhalation time; and

determining that the maximum exhalation time has expired.

5. The method of claim 1, further comprising:

estimating a leak flow from a ventilation tubing system; and

adjusting the initial base flow and the desired base flow to account for the estimated leak flow from the ventilation tubing system.

6. A method for ventilating a patient with a ventilator, comprising:

determining an initial base flow;

determining an initial inspiration trigger threshold;

delivering the initial base flow during at least a first portion of exhalation while setting the inspiration trigger threshold to the initial inspiration trigger threshold;

increasing base flow from the initial base flow toward a first flow value during at least a second portion of exhalation; and

decreasing the inspiration trigger threshold from the initial inspiration trigger threshold toward a first trigger threshold value while performing the step of increasing the base flow.

7. The method of claim 6, wherein the step of increasing the base flow includes increasing the base flow at a first exponential trajectory.

8. The method of claim 7, wherein the step of increasing the base flow is performed until at least one of a desired base flow is substantially reached and an inspiration trigger is detected.

9. The method of claim 7, wherein the step of decreasing the inspiration trigger threshold includes decreasing the inspiration trigger threshold at a second exponential trajectory.

10. The method of claim 9, wherein the step of decreasing the inspiration trigger threshold is performed until at least one of a desired inspiration trigger threshold is substantially reached and an inspiration trigger is detected.

11. The method of claim 9, wherein a slope of the first exponential trajectory of the base flow and a slope of the second exponential trajectory of the inspiration trigger threshold is based on a time constant selected by the ventilator.

12. The method of claim 7, wherein a slope of the first exponential trajectory of the base flow is based on a constant selected by the ventilator.

13. The method of claim 6, wherein the step of decreasing the inspiration trigger threshold includes decreasing the inspiration trigger threshold at an exponential trajectory until at least one of a desired inspiration trigger threshold is substantially reached and an inspiration trigger is detected.

14. The method of claim 6, wherein the initial base flow is zero.

15. The method of claim 6, wherein the initial inspiration trigger threshold is a change in flow of at least 6 LPM.

16. The method of claim 6, wherein the second portion of exhalation begins based on an occurrence of a condition, the condition being at least one of a group including:

determining that a minimum exhalation time has expired;

determining that a monitored exhalation flow is below a minimum exhalation flow;

determining that the monitored exhalation flow is below the minimum exhalation flow prior to expiration of a maximum exhalation time; and

determining that the maximum exhalation time has expired.

17. The method of claim 6, further comprising:

estimating a leak flow from a ventilation tubing system; and

adjusting the initial base flow and the first flow value to account for the estimated leak flow from the ventilation tubing system.

18. The method of claim 6, wherein the step of increasing the base flow and the step of decreasing the inspiration trigger threshold are performed concurrently.

19. The method of claim 6, wherein the inspiration trigger threshold is at least one of a change in exhalation flow and a change in exhalation pressure.

20. The method of claim 6, further comprising:

calculating an estimated exhaled tidal volume of the patient.

21. The method of claim 6, further comprising:

displaying at least one of a minimum exhalation flow, a minimum exhalation time, a maximum exhalation time, a desired base flow, a desired inspiration trigger threshold, the inspiration trigger threshold, the base flow, an exhalation flow, an estimated leak flow, and an exhalation pressure.

22. A ventilator system comprising:

a pressure generating system adapted to generate a flow of breathing gas;

a ventilation tubing system including a patient interface for connecting the pressure generating system to a patient;

at least one sensor operatively coupled to at least one of the pressure generating system, the patient, and the ventilation tubing system;

a base flow trajectory module for delivering a base flow during exhalation,

wherein the base flow trajectory module determines an initial base flow to deliver during at least a first portion exhalation, and

wherein the base flow trajectory module increases the base flow delivered to the patient from the initial base flow toward a desired base flow during at least a second portion of the exhalation;

an inspiratory trigger trajectory module sets an inspiration trigger threshold during the exhalation,

wherein the inspiratory trigger trajectory module sets an initial inspiration trigger threshold while delivering the initial base flow, and

wherein the inspiratory trigger trajectory module decreases the inspiration trigger threshold from the initial inspiration trigger threshold towards a desired inspiration trigger threshold while the base flow trajectory module increases the base flow delivered to the patient circuit tubing; and

a processor in communication with the pressure generating system, the at least one sensor, inspiratory trigger trajectory module, and the base flow trajectory module.

23. The ventilator system of claim 22, further comprising:

a leak estimation module, the leak estimation module determines an amount of flow leaked from the ventilation tubing system,

wherein the initial base flow and the desired base flow are adjusted to account for the amount of flow leaked from the ventilation tubing system.

24. The ventilator system of claim 22, further comprising:

a display in communication with the processor, the display displays at least one of a minimum exhalation flow, a minimum exhalation time, a maximum exhalation time, the desired base flow, the desired inspiration trigger threshold, the inspiration trigger threshold, the base flow, an exhalation flow, an estimated leak flow, and an exhalation pressure.

25. The ventilator system of claim 22, wherein the processor is configured to calculate an estimated exhaled tidal volume based on the output from the at least one sensor.

26. A computer-readable medium having computer-executable instructions for performing a method of ventilating a patient with a ventilator, the method comprising:

repeatedly determining an initial base flow;

repeatedly determining an initial inspiration trigger threshold;

repeatedly delivering the initial base flow during at least a first portion of exhalation while setting the inspiration trigger threshold to the initial inspiration trigger threshold;

repeatedly increasing base flow from the initial base flow toward a first flow value during at least a second portion of exhalation; and

repeatedly decreasing an inspiration trigger threshold from the initial inspiration trigger threshold toward a first trigger threshold value while performing the step of increasing the base flow.

27. A ventilator system, comprising:

means for determining an initial base flow;

means for determining an initial inspiration trigger threshold;

means for delivering the initial base flow during at least a first portion of exhalation while setting the inspiration trigger threshold to the initial inspiration trigger threshold;

means for increasing base flow from the initial base flow toward a first flow value during at least a second portion of exhalation; and

means for decreasing an inspiration trigger threshold from the initial inspiration trigger threshold toward a first trigger threshold value while performing the step of increasing the base flow.