METHODS AND SYSTEMS FOR ADAPTIVE ADJUSTMENT OF VENTILATOR SETTINGS

• US 20140373845A1
• Filed: 06/25/2013
• Published: 12/25/2014
• Est. Priority Date: 06/25/2013
• Status: Abandoned Application

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Dong, Nancy F.
• Application Number:
  US13/926,013
• Publication Number:
  US 20140373845A1
• Time in Patent Office: Days
• US Class Current: 128/204.23
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• 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 16/0883 Circuit type
• 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 2205/502 User interfaces, e.g. screens or keyboards

Abstract

This disclosure describes systems and methods for providing optimized adjustment of a ventilator based on an estimated net value of patient effort. The disclosure describes a novel breath type that delivers a target airway pressure calculated based on an estimated patient muscle effort. A net value of patient muscle effort is estimated using a parameter estimate vector update equation to solve for a recursive least squares gain value representing the estimated net value of patient effort. The estimated net value of patient muscle effort is used to determine a target airway pressure, which is then used to determine a target inspiratory pressure to be delivered to a patient. The target inspiratory pressure is used to determine an onset and/or end of a ventilation cycle and therefore improves the synchronization between the ventilator and the patient.

Claims

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

receiving a plurality of ventilator parameters;

estimating a net value of patient muscle effort based on the received ventilator parameters, wherein the net value of patient muscle effort is estimated using a parameter estimate vector update equation to solve for a recursive least squares gain value representing the estimated net value of patient effort at a time instance by subtracting a squared gain value for a previous time instance multiplied by a regression parameter vector at the time instance and a transpose of the regression parameter vector at the time instance and a transpose of the squared gain value for the previous time instance divided the result by one plus the transpose of the regression parameter vector at the time instance multiplied by the squared gain value for the previous time instance multiplied by the regression parameter vector at the time instance from the gain value for the previous time instance; and

calculating target inspiratory pressure based on the estimated net value of patient effort.

2. The method of claim 1, wherein receiving a plurality of ventilator parameters includes receiving raw measurement parameter data or parameter estimates from at least one sensor.

3. The method of claim 2, wherein raw measurement parameter data includes at least one of inspiratory flow, expiratory flow, inspiratory pressure, and expiratory pressure.

4. The method of claim 2, wherein parameter estimates include at least one of an estimate of inspiratory limb resistance, expiratory limb resistance, inspiratory limb compliance, expiratory limb and flow rate in a ventilation tube.

5. The method of claim 1, wherein estimating a net value of patient muscle effort includes:

applying a forgetting factor to the parameter estimate vector update equation.

6. The method of claim 1, further comprising calculating the target inspiratory pressure for a next time instance by adding the estimated net value of patient muscle effort at a time instance to the sum of the product of an estimated inverse limb compliance value and lung volume value at the time instance and the product of an estimated resistance value at a time instance and a lung flow rate at the time instance.

7. The method of claim 6, further comprising:

using the target inspiratory pressure to calculate an adjusted target airway pressure by subtracting the calculated target inspiratory pressure at the time instance from the product of a flow rate and a resistance value at the time instance.

8. The method of claim 7, further comprising:

delivering the adjusted target airway pressure to a patient.

9. 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;

one or more sensors operatively coupled to at least one of the pressure generating system, the patient, and the ventilation tubing system, wherein the one or more sensors generate output indicative of an inspiration flow;

an adaptive calculation module adapted to perform quantification of patient muscle by establishing a respiratory predictive model of the ventilator based on an equation of motion and received raw measurement parameter data or estimated ventilator parameters and extracting an estimated net value of patient muscle effort by solving for a recursive least squares gain value representing the estimated net value of patient muscle effort at a time instance by subtracting a squared gain value for a previous time instance multiplied by a regression parameter vector at the time instance and a transpose of the regression parameter vector at the time instance and a transpose of the squared gain value for the previous time instance divided the result by one plus the transpose of the regression parameter vector at the time instance multiplied by the squared gain value for the previous time instance multiplied by the regression parameter vector at the time instance from the gain value for the previous time instance; and

a support module operable to adjust a target inspiratory pressure based on the estimated net value of patient muscle effort or one or more other respiratory parameters derived based on the estimated net value of patient muscle effort.

10. The ventilator system of claim 9, wherein raw measurement parameter data includes at least one of inspiratory flow, expiratory flow, inspiratory pressure, and expiratory pressure.

11. The ventilator system of claim 9, wherein at least one estimated ventilator parameter includes at least one of an estimate of inspiratory limb resistance, expiratory limb resistance, inspiratory limb compliance, expiratory limb and flow rate in a ventilation tube.

12. The ventilator system of claim 9, wherein the adaptive calculation module applies a forgetting factor to the parameter estimate vector update equation to estimate the net value of patient muscle effort.

13. The ventilator system of claim 9, wherein the support module calculates a target inspiratory pressure based at least on the net value of patient muscle effort.

14. The ventilator system of claim 13, wherein the support module calculates the target inspiratory pressure for a next time instance by adding the estimated net value of patient muscle effort at a time instance to the sum of the product of an estimated inverse limb compliance value and lung volume value at the time instance and the product of an estimated resistance value at the time instance and a lung flow rate at the time instance.

15. The ventilator system of claim 14, wherein the support module uses the target inspiratory pressure to calculate an adjusted target airway pressure by subtracting the calculated target inspiratory pressure at the time instance from the product of a flow rate and a resistance value at the time instance.

16. The ventilator system of claim 15, wherein the support module sends the calculated target inspiratory pressure to at least one ventilator component for delivery of the adjusted target airway pressure to a patient.

17. The ventilator system of claim 15, further comprising a display that displays at least one of the net value of patient muscle effort or an initial support setting based on the calculated target inspiratory pressure.

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

receiving a plurality of ventilator parameters;

estimating a net value of patient muscle effort based on the received ventilator parameters, wherein the net value of patient muscle effort is estimated using a parameter estimate vector update equation to solve for a recursive least squares gain value representing the estimated net value of patient muscle effort at a time instance by subtracting a squared gain value for a previous time instance multiplied by a regression parameter vector at the time instance and a transpose of the regression parameter vector at the time instance divided the result by one plus a gain value for the previous time instance multiplied by the transpose of the regression parameter vector at the time instance multiplied by the regression parameter vector at the time instance from the gain value for the previous time instance;

calculating target inspiratory pressure based on the estimated net value of patient muscle effort; and

sending the target inspiratory pressure to a ventilator component to optimally adjust a delivered target airway pressure based on the target inspiratory pressure.

19. The ventilator system of claim 18, further comprising calculating the target inspiratory pressure for a next time instance by adding the estimated net value of patient muscle effort at the time instance to the sum of the product of an estimated inverse limb compliance value and lung volume value at the time instance and the product of an estimated resistance value at the time instance and a lung flow rate at the time instance.

20. The ventilator system of claim 18, further comprising:

using the target inspiratory pressure to calculate an adjusted target airway pressure by subtracting the calculated target inspiratory pressure at the time instance from the product of a flow rate and a resistance value at the time instance.