Systems and methods for compensating long term sensitivity drift of electrochemical gas sensors exposed to nitric oxide

• US 10,195,380 B2
• Filed: 11/02/2016
• Issued: 02/05/2019
• Est. Priority Date: 02/19/2014
• Status: Active Grant

• Current Assignee: Mallinckrodt Pharma Ip Trading DAC (Mallinckrodt plc)
• Original Assignee: Mallinckrodt Hospital Products IP Ltd. (Mallinckrodt plc)
• Inventors: Tolmie, Craig R., Milsap, Jeff, Acker, Jaron M.
• Primary Examiner(s): Anderson, Gregory
• Assistant Examiner(s): Paciorek, Jonathan
• Application Number:
  US15/341,262
• Publication Number:
  US 20170072157A1
• Time in Patent Office: 825 Days
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/085 Gas sampling
• CPC Class Codes: A61M 16/1005 with O2 features or with parameter measurement
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 16/16 Devices to humidify the respiration air A61M16/1045 takes precedence
• CPC Class Codes: A61M 16/201 Controlled valves
• CPC Class Codes: A61M 2016/102 Measuring a parameter of the content of the delivered gas
• CPC Class Codes: A61M 2016/1035 the anaesthetic agent concentration
• CPC Class Codes: A61M 2202/0007 introduced into the body
• CPC Class Codes: A61M 2202/0275 Nitric oxide [NO]
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/27 preventing use
• CPC Class Codes: A61M 2205/33 Controlling, regulating or measuring
• CPC Class Codes: A61M 2205/502 User interfaces, e.g. screens or keyboards
• CPC Class Codes: A61M 2205/52 with memories providing a history of measured variating parameters of apparatus or patient
• CPC Class Codes: A61M 2205/581 by audible feedback
• CPC Class Codes: A61M 2205/583 by visual feedback
• CPC Class Codes: A61M 2205/70 with testing or calibration facilities
• CPC Class Codes: A61M 2205/702 : automatically during use
• CPC Class Codes: G01N 27/4163 : checking the operation of, or calibrating, the measuring apparatus G01N27/3274, G01N27/4175 and G01N33/0006 take precedence
• CPC Class Codes: G01N 33/0006 : Calibrating gas analysers
• CPC Class Codes: G01N 33/0008 : Details concerning storage of calibration data, e.g. in EEPROM
• CPC Class Codes: G01N 33/0037 : for NOx
• CPC Class Codes: Y02A 50/20 : Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

Systems and methods for compensating long term sensitivity drift of catalytic type electrochemical gas sensors used in systems for delivering therapeutic nitric oxide (NO) gas to a patient by compensating for drift that may be specific to the sensors. In at least some instances, the long term sensitivity drift of catalytic type electrochemical gas sensors can be addressed using calibration schedules, which can factor in the absolute change in set dose of NO being delivered to the patient that can drive one or more baseline calibrations. The calibration schedules can reduce the amount of times the sensor goes offline. Systems and methods may factor in actions occurring at the delivery system and/or aspects of the surrounding environment, prior to performing a baseline calibration, and may postpone the calibration and/or rejected using the sensor'"'"'s output for the calibration.

Claims

1. A method for delivering notifications of a calibration status for a sensor associated with a therapeutic gas delivery device, the method comprising:

storing in memory a baseline calibration value, slope, and calibration schedule;

monitoring a patient intake of therapeutic gas with the sensor;

delivering, via the therapeutic gas delivery device, a predetermined dosage of therapeutic gas to the patient;

measuring a concentration of therapeutic gas from the delivered predetermined dosage;

retrieving, from memory, the baseline calibration value, slope and calibration schedule;

performing a zero calibration according to the calibration schedule, wherein the zero calibration includes exposing the sensor to a zero concentration of the therapeutic gas and adjusting the baseline calibration value according to a sensor output value during the zero calibration;

determining, after a predetermined number of zero calibration attempts, that the zero calibration has failed; and

notifying a user that the zero calibration has failed.

2. The method of claim 1 wherein the therapeutic gas is nitric oxide.

3. The method of claim 1 wherein the user is notified with an alarm.

4. The method of claim 1 wherein the notifying includes displaying a message on a display screen.

5. The method of claim 1 wherein performing the zero calibration further comprises notifying the user that the zero calibration is currently in effect.

6. The method of claim 5 wherein the notifying the user further comprises displaying a notification that the measuring of therapeutic gas concentration is off-line.

7. The method of claim 1 wherein the predetermined number of zero calibration attempts is three.

8. The method of claim 7 wherein the three zero calibration attempts include a first initial calibration attempt, and two re-try zero calibration attempts.

9. The method of claim 8 wherein, after the first initial zero calibration attempt, the method further comprises re-trying the zero calibration attempt after a predetermined period of time has passed.

10. A method for delivering notifications of a calibration status for a sensor associated with a nitric oxide delivery device, the method comprising:

storing in memory a baseline calibration value, slope, and calibration schedule;

monitoring a patient intake of nitric oxide with the sensor;

delivering, via the nitric oxide delivery device, a predetermined dosage of nitric oxide to the patient;

measuring a concentration of nitric oxide from the delivered predetermined dosage;

retrieving, from memory, the baseline calibration value, slope and calibration schedule;

performing a zero calibration according to the calibration schedule, wherein the zero calibration includes exposing the sensor to a zero concentration of the nitric oxide and adjusting the baseline calibration value according to a sensor output value during the calibration;

determining, after a zero calibration attempt, that calibration has failed;

notifying a user that the zero calibration has failed; and

re-attempting the zero calibration after a predetermined period of time.

11. The method of claim 10 wherein upon completion of the zero calibration, the method further comprises determining an actual concentration of nitric oxide delivered in the predetermined dosage to compensate for sensor drift by adjusting the value of the measured concentration based on the adjusted baseline value and the slope.

12. The method of claim 10 further comprising setting a maximum number of allowable zero calibration re-attempts.

13. The method of claim 12 wherein after the maximum number of allowable zero calibration re-attempts, the method further comprises performing a calibration lockout.

14. The method of claim 13 wherein the calibration lockout further comprises notifying the user with an alarm.

15. The method of claim 10 wherein the zero calibration failed because of an improperly functioning valve.

16. The method of claim 10 further comprising determining, after the re-attempted zero calibration, that the zero calibration failed as a result of both zero calibration attempts producing sensor output values outside an allowable threshold value range.

17. A method for delivering notifications of a calibration status for a sensor associated with a nitric oxide delivery device, the method comprising:

storing in memory a baseline calibration value, slope, and calibration schedule;

monitoring a patient intake of nitric oxide with the sensor;

delivering, via the nitric oxide delivery device, a predetermined dosage of nitric oxide to the patient;

measuring a concentration of nitric oxide from the delivered predetermined dosage;

retrieving, from memory, the baseline calibration value, slope and calibration schedule;

performing a zero calibration according to the calibration schedule, wherein the calibration includes exposing the sensor to a zero concentration of the nitric oxide and adjusting the baseline calibration value according to a sensor output value during the calibration;

determining, after a zero calibration attempt, that the zero calibration has failed;

determining that a sensor output values is outside an allowable threshold value range; and

re-attempting the zero calibration after a predetermined period of time;

transmitting a notification to a user that calibration has failed.

18. The method of claim 17 wherein the notification includes displaying the notification during the performing of the zero calibration, and further includes displaying the notification for an additional period of time after the performing of the zero calibration is completed.

19. The method of claim 18 wherein the additional period of time corresponds to an amount of time for the sensor to settle.

20. The method of claim 18 wherein the nitric oxide sensor is exposed to the gas having a zero concentration of nitric oxide for a predetermined interval before the calibration line is adjusted.