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

Inventors

Tolmie, Craig R. • Milsap, Jeff • Acker, Jaron M.

Assignees

Mallinckrodt Pharma IP Trading DAC • Therakos Inc • INO Therapeutics LLC • Mallinckrodt Critical Care Finance Inc

Abstract

Described are 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 atypical use in systems for delivering therapeutic nitric oxide gas to a patient. The long term sensitivity drift of catalytic type electrochemical gas sensors may 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 be used to reduce the amount of times the sensor goes offline.

Core Innovation

The invention relates to compensating long-term sensitivity/output drift of a nitric oxide (NO) electrochemical gas sensor used in therapeutic gas delivery. A predetermined dosage of therapeutic gas comprising nitric oxide is delivered to a breathing circuit for delivery to a patient, and the nitric oxide sensor continuously monitors a signal indicative of a concentration of nitric oxide in the breathing circuit. After nitric oxide sensor calibration occurs, the system determines a compensated response to the sensor signal indicative of the nitric oxide concentration in the breathing circuit.

A core part of the approach is controlling when the nitric oxide sensor calibration is executed according to an identified sensor calibration schedule stored in system controller memory. Calibration is postponed if an alarm is active or has been active within a predetermined timeframe at the time calibration is to be executed, and calibration is executed when the active alarm is not detected or has not been detected within the predetermined timeframe. The calibration schedule is modified based upon a change in the predetermined dosage of nitric oxide being delivered to the patient, where an increase in the predetermined dosage results in the nitric oxide sensor calibration occurring with a greater frequency.

The disclosed calibration and drift compensation logic further includes baseline calibration updates using a stored baseline response and slope from a previous calibration. Calibration activity can be surfaced through notification and electronic medical record (EMR) logging, and the system may display a message indicating that calibration is in effect. Valve-based switching using a three-way valve is described to expose the sensor to breathing-circuit gas versus conditioned ambient air without disconnecting sampling lines.

Claims Coverage

The independent claims identified are clm-00001, clm-00019, and clm-00020. Across these claims, the coverage centers on postponing nitric-oxide sensor calibration based on system alarm activity and user interaction, modifying a calibration schedule in response to changes in the predetermined nitric-oxide dosage, and then producing a compensated response, with display and EMR recording in one claim.

Across clm-00001, clm-00019, and clm-00020, the claims cover methods for compensating electrochemical nitric-oxide sensor output drift in therapeutic gas delivery by controlling calibration timing based on whether an alarm is active within a predetermined timeframe and whether a user is interacting within the same timeframe, while also modifying the calibration schedule based on increases in the predetermined nitric-oxide dosage. After calibration, the system determines a compensated response to the nitric-oxide concentration signal, and clm-00020 further requires user-facing and/or EMR recording of calibration occurrence.

Stated Advantages

Documented Applications