Adaptive Flow Sensor Model

• US 20110146681A1
• Filed: 12/21/2009
• Published: 06/23/2011
• Est. Priority Date: 12/21/2009
• Status: Abandoned Application

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett LLC (Medtronic Plc)
• Inventors: McCoy, Edward, Upham, Gail F., Jafari, Mehdi M., Jimenez, Rhomere S.
• Application Number:
  US12/643,083
• Publication Number:
  US 20110146681A1
• Time in Patent Office: Days
• US Class Current: 128/204.21
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• 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 16/0833 T- or Y-type connectors, e.g. Y-piece
• CPC Class Codes: A61M 16/085 Gas sampling
• CPC Class Codes: A61M 16/0858 Pressure sampling ports
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2205/17 with redundant control systems
• CPC Class Codes: A61M 2205/505 Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: A61M 2205/702 automatically during use

Abstract

The disclosure describes a novel approach of estimating patient sensor data for sensors in sensor tubing or sensor lines during purging or autozeroing or any other situations under which no measurement is provided by the sensor.

Claims

1. A method for estimating at least one patient reading from at least one circuit sensor in a medical ventilator providing ventilation to a patient, the method comprising:

monitoring a plurality of sensors including a first sensor and at least one second sensor to obtain first sensor measurements and second sensor measurements;

fitting a curve for first sensor measurements versus time based on the second sensor measurements, wherein said fitting relies on one or more fit parameters, and wherein the values of said one or more fit parameters are found by said fitting;

calculating an estimate of first sensor measurements for a time interval based on the one or more fit parameters and the second sensor measurements; and

displaying the estimate of the first sensor measurements for the time interval instead of the first sensor measurements.

2. The method of claim 1 wherein displaying further comprising:

displaying the estimate of the first sensor measurements for the time interval instead of the first sensor measurements when the first sensor measurements are a predetermined value.

3. The method of claim 1 further comprising:

displaying the first sensor measurements for the time interval only when the first sensor measurements are not the predetermined value.

4. The method of claim 1 wherein displaying further comprising:

displaying the estimate of the first sensor measurements for the time interval instead of the first sensor measurements when the ventilator is performing a predetermined action.

5. The method of claim 3 wherein displaying further comprising:

detecting a purge of sensor lines associated with the first sensor; and

displaying the estimate of the first sensor measurements for the time interval instead of the first sensor measurements when the ventilator is performing a purge of sensor lines associated with the first sensor.

6. The method of claim 1 wherein displaying further comprising:

displaying the estimate of the first sensor measurements for the time interval instead of the first sensor measurements when the first sensor is turned off.

7. The method of claim 1 wherein displaying further comprising:

displaying the estimate of the first sensor measurements for the time interval instead of the first sensor measurements when the first sensor measurements are about zero.

8. The method of claim 1 wherein model equations (in time and frequency domains) for the curve fitted are:

9. A pressure support system comprising:

a processor;

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

a ventilation system including a patient circuit controlled by the processor;

at least one circuit sensor in fluid controlled by the patient circuit via one or more sensor tubes; and

an adaptive flow sensor model controlled by the processor, the adaptive flow sensor model is adapted to estimate patient sensor data during situations in which the at least one circuit sensor cannot obtain a reading.

10. The pressure support system of claim 9, wherein the adaptive flow sensor model is controlled by the circuit sensor.

11. The pressure support system of claim 9, wherein the adaptive flow sensor model is controlled by the ventilation system.

12. The pressure support system of claim 9, further comprising an autozeroing mechanism controlled by the processor and adapted to recalibrate the at least one sensor circuit discontinuing any readings of the least one circuit sensor;

and

13. The pressure support system of claim 9, further comprising a sensor tube purge model in controlled by the processor and adapted to initiate a purge cycle that purges the sensor tubes, wherein each purge cycle includes repeatedly discharging gas through the sensor tubes into the patient circuit and discontinuing any readings of the least one circuit sensor.

14. The pressure support system of claim 9, wherein the adaptive flow sensor model is adapted to utilize the following model equations to estimate patient sensor data:

15. The pressure support system of claim 9, further comprising a display controlled by the processor, the display is adapted to display the estimated patient sensor data.

16. A medical ventilator system, comprising:

a processor;

a gas regulator controlled by the processor, the gas regulator adapted to regulate a flow of gas from a gas supply to a patient via a patient circuit;

a flow sensor package disposed in the patient circuit, the flow sensor package controlled by a gas accumulator;

a pressure sensor coupled to the gas accumulator and controlled by the processor, the pressure sensor adapted to provide pressure readings in the gas accumulator to the processor; and

an adaptive flow sensor model controlled by the processor for estimating patient sensor data when the flow sensor and pressure sensor are not reading patient data.

17. The medical ventilator system of claim 16, wherein the adaptive flow sensor model is controlled by the circuit sensor.

18. The medical ventilator system of claim 16, wherein the adaptive flow sensor model is controlled by the ventilation system.

19. The medical ventilator system of claim 16, wherein the adaptive flow sensor model is adapted to utilize the following model equations to estimate patient sensor data:

20. The medical ventilator system of claim 16, further comprising a display controlled by the processor, the display is adapted to display the estimated patient sensor data.