SYSTEMS AND METHODS FOR LONG-TERM COMPENSATION FOR THE SENSITIVITY OF DRIFT IN ELECTROCHEMICAL GAS SENSORS EXPOSED TO NITRIC OXIDE.

Abstract

The present invention describes systems and methods for compensating for long-term drift sensitivity in catalytic-type electrochemical gas sensors used in systems for delivering therapeutic nitric oxide (NO) gas to a patient. This is achieved by compensating for drift that may be specific to sensors used atypically in these systems. In at least some cases, the long-term drift sensitivity of catalytic-type electrochemical sensors can be addressed by calibration programs. These programs can account for absolute changes in the set dose of NO delivered to the patient, which may lead to one or more baseline calibrations. The calibration programs used can reduce the number of times the sensor shuts down.The systems and methods described may take into account actions occurring in the supply system and / or aspects of the surrounding environment before performing a baseline calibration, and may postpone calibration and / or reject the use of the sensor output for calibration.

Description

SYSTEMS AND METHODS FOR LONG-TERM COMPENSATION FOR THE SENSITIVITY OF DRIFT IN ELECTROCHEMICAL GAS SENSORS EXPOSED TO NITRIC OXIDE FIELD OF INVENTION The present invention relates in general to systems and methods for long-term compensation of the drift sensitivity of electrochemical gas sensors exposed to nitric oxide, for example, in a controlled environment. BACKGROUND OF THE INVENTION There are many variations of electrochemical sensors that, while they may appear similar, function very differently. For example, some electrochemical sensors can be used to detect the presence of a specific gas, while others detect concentrations of a specific gas. Furthermore, some electrochemical sensors work with liquids but not with gases. Focusing on electrochemical gas sensors, some of these gas sensors use galvanic reactions, while others use catalytic reactions. Additionally, some of these gas sensors require electricity to operate, while others do not, and in some cases, these sensors actually generate electricity.Furthermore, within similar types of electrochemical gas sensors that have the same electrical requirements, this small subset of sensors can have a great deal of variation depending on the cell function and / or the gas that reacts with the cell. Focusing on catalytic-type electrochemical gas sensors, these sensors are typically used as toxic gas sensors. When used as toxic gas sensors (e.g., for monitoring chimney smoke emissions), these sensors can only be exposed to the toxic gas for short or intermittent periods of operation and / or can only be used to detect low, meaningful concentrations of a gas (e.g., gas at concentrations in the parts per billion (ppb) range). However, unlike their use as toxic gas sensors, systems for delivering therapeutic nitric oxide gas to a patient can utilize catalytic-type electrochemical gas sensors to confirm the precise dose of a therapeutic gas such as inhaled nitric oxide (NO).These delivery systems, which include catalytic-type electrochemical gas sensors, can be used to deliver therapeutic nitric oxide to a patient at a parts-per-million dose (e.g., 1 ppm to 80 ppm, 0.1 ppm to 80 ppm, etc.) for an extended period of time (e.g., many hours, days, weeks, months, etc.) under continuous gas monitoring. P LO L Ln / L7A7 / B / YL In general, the use of catalytic electrochemical gas sensors in systems for delivering therapeutic nitric oxide gas to a patient is considered atypical and can present problems not encountered when these sensors are used more conventionally (e.g., in typical toxic gas sensor applications). These issues can be important for users (e.g., physicians, nurses, etc.) and may require confirmation of the therapeutic drug dosage based on the sensor output. Consequently, there is a need to overcome these problems to at least ensure accurate dosage confirmation. BRIEF DESCRIPTION OF THE INVENTION There are several ways to address the above problems, including, for example, performing sensor calibrations at predetermined time intervals, issuing messages and / or indicators that alert the user to operating conditions and calibration performance, using dual sensors to measure the amount of target gas in a breathing circuit, and detecting whether the sensor output is outside a threshold range. Principles and modalities generally refer to a method for compensating for the output drift of an electrochemical gas sensor exposed to nitric oxide in a controlled environment, comprising identifying a time for running a calibration of a scheduled sensor recalibration, which is stored in a memory of the system controller and detecting whether an alarm is active or has been active within a predetermined time frame at the time the calibration is run, wherein the calibration is postponed if the alarm is active or has been detected within the predetermined time period and the calibration is run if the alarm is not active or has not been detected within the predetermined time frame. The modalities also relate to establishing a target gas dose to be delivered to a breathing circuit indicated by a setting on a system controller, identifying a change in the setting on the system controller, calculating the magnitude of a change in the target gas dose being delivered to the breathing circuit, identifying the programmed recalibration sensor stored in the system controller's memory that is specific to the magnitude of the change in the target gas dose, and implementing the programming of the identified recalibration sensor. The modalities also refer to the continuous measurement of the target gas concentration in the breathing circuit with a first sensor, which communicates a signal representative of the target gas concentration from the first sensor to the controller of the P LO L Ln / L7A7 / B / YL system through a communication route and the determination of a response of the first sensor to the change in the target gas concentration. The modalities also refer to the interruption of the continuous measurement of the target gas concentration when indicated by the programming of the identified recalibration sensor, exposing the first sensor to a gas that has a concentration of zero of the target gas for a period of time sufficient to detect the output value indicative of the zero concentration and determine the response with the first sensor of the gas that has a concentration of zero of the target gas. The modes also refer to a recalibration sensor program comprising a set of values ​​that represent intervals between interruptions of the continuous measurement of the target gas concentration. The modes also relate to intervals that are larger for a smaller change in the configuration in the system controller. The modes also relate to storing the response of the first gas sensor that has a zero concentration of the target gas in the system controller's memory. The modes also relate to accessing a slope line from the previous calibration stored in the system controller's memory and generating a new calibration line using the stored response from the first gas sensor that has the target gas concentration of zero and the slope line from the previous calibration. The modalities also refer to the identification of the type of the first continuous measurement sensor, the concentration of the target gas in the breathing circuit, the storage of the type of the first sensor in the system controller, and the use of the first sensor in identifying the recalibration sensor programming. The modalities also refer to a first sensor that is either a three-terminal electrochemical nitric oxide gas sensor or a four-terminal electrochemical nitric oxide gas sensor. The modes also refer to the selection of an ambient air source that flows to the first sensor when continuous measurement of the target gas concentration in the breathing circuit is interrupted, without needing to disconnect the sampling line from an inspiratory side of the patient's breathing circuit. The modalities also refer to the switching of a valve connected and in fluid communication with the patient's breathing circuit to allow ambient air to flow to the first sensor when continuous measurement of the target gas concentration in the breathing circuit is interrupted without the need to disconnect a sampling line from one inspiratory side of the patient's breathing circuit. P LO L Ln / L7A7 / B / YL The modalities also refer to verifying that the valve has changed so that ambient air flows to the sensor. The modes also relate to postponing the execution of the calibration for a predetermined period of time and detecting whether an alarm is active or has been active within a predetermined time frame after the predetermined period of time has elapsed, where the calibration is postponed if an active alarm is detected or has been detected within a predetermined time and the calibration is executed if the active alarm is not detected or has not been detected within a predetermined time. The modalities also relate to (i) detecting the presence of interfering gas and postponing the execution of the calibration for a predetermined period of time if interfering gas is detected and / or (ii) detecting whether a user is interacting or has interacted with the therapeutic gas delivery system within a predetermined time frame at the time the calibration is to be executed. The modes also refer to the display of a message to a user when the measurement of the target gas concentration in the breathing circuit is interrupted to perform calibration with the first sensor. The modes also refer to measuring the concentration of the target gas in the breathing circuit with a second sensor when the measurement of the concentration of the target gas in the breathing circuit with the first sensor is interrupted, so that a measurement of the concentration of the target gas is shown to a user during recalibration. The modalities also refer to the exposure of the second sensor to the gas that has a zero concentration of the target gas for a period of time sufficient to remove saturation and / or detect the output value indicative of zero concentration after the exposure of the first sensor to the gas that has a zero concentration of the target gas for a period of time sufficient to remove saturation and / or detect the output value indicative of zero concentration and comparing the output value of the second sensor with the output value of the first sensor to determine the difference in drift between the first and second sensor. Principles and modalities also generally refer to a method for compensating for the output drift of an electrochemical gas sensor exposed to nitric oxide in a controlled environment, comprising identifying a time for running a calibration of a programmed recalibration sensor stored in a system controller memory, detecting whether an alarm is active or has been active within a predetermined time frame at the time the calibration is run, wherein the calibration is postponed if an active alarm is detected or has been detected within the time period P LO L Ln / I 7P7 / E / Y1i default, detect if a user is interacting or has interacted with the therapeutic gas delivery system within a predetermined time frame at the time of calibration execution, wherein the calibration is postponed if the user is interacting or has interacted with the therapeutic gas delivery system within the predetermined time frame, detect if one or more interfering gases are causing or have caused the sensor output to be out of a threshold range within a predetermined time frame at the time the calibration is to be executed, wherein the calibration is postponed if the sensor output is or has been out of range within the predetermined time frame at the time the calibration is to be executed, the execution of the calibration (i) if the active alarm is not detected or has not been detected within the predetermined time period,(i) if the user is not interacting or has not interacted with the therapeutic gas delivery system within the predetermined time frame and (iii) if the sensor output is not or is not out of range within a predetermined time frame. Principles and modalities also generally refer to a method for compensating for the output drift of an electrochemical gas sensor exposed to nitric oxide in a controlled environment, comprising delivering a therapeutic gas comprising NO to a patient in need thereof, detecting a change in the set dose of the therapeutic gas, selecting a sensor recalibration program stored in a system controller memory in response to the change in the set dose, identifying a time for running a calibration of the selected sensor recalibration program, detecting whether an alarm is active or has been active within a predetermined time frame at the time the calibration is to be run, wherein the calibration is postponed if an active alarm is detected or has been detected within the predetermined time period,detect whether a user is interacting or has interacted with the therapeutic gas delivery system within a predetermined time frame at the time the calibration is to be executed, wherein the calibration is postponed if the user is interacting or has interacted with the therapeutic gas delivery system within the predetermined time frame, detect whether one or more interfering gases are causing or have caused the sensor output to be out of a threshold range within a predetermined time frame at the time the calibration is to be executed, wherein the calibration is postponed if the sensor output is or has been out of range within the predetermined time frame at the time the calibration is to be executed, the execution of the calibration (i) if the active alarm is not detected or has not been detected within the predetermined time period,(i) if the user is not interacting or has not interacted with the therapeutic gas delivery system within the predetermined time frame and (iii) if the sensor output is not or has not been out of range within a, P LO L Ln / L7A7 / B / YL default time frame and display a message to a user, when running a calibration, indicating that the calibration is taking place and / or record the occurrence of a calibration in an electronic medical record (EMR) to inform the user of the system activity. BRIEF DESCRIPTION OF THE DRAWINGS The features and advantages of the present invention will be more fully understood with reference to the following detailed description when taken in conjunction with the accompanying figures, where: Figures 1A-1B illustratively represent exemplary systems, including exemplary catalytic-type electrochemical gas sensors, for the delivery of therapeutic nitric oxide gas to a patient in need thereof, according to exemplary modalities of the present invention. Fig. 2A illustrates an exemplary catalytic-type three-terminal electrochemical gas sensor, according to exemplary embodiments of the present invention. Fig. 2B illustrates an exemplary catalytic-type four-terminal electrochemical gas sensor, according to exemplary embodiments of the present invention. Fig. 3 illustratively represents an example of a two-point linear interpolation calibration line, according to exemplary embodiments of the present invention. Figures 4-9 illustratively represent exemplary drifts of exemplary catalytic-type electrochemical gas sensors in exemplary systems for the delivery of therapeutic nitric oxide gas to a patient, according to exemplary modalities of the present invention. Fig. 10 illustrates an exemplary flowchart for a dose-change response algorithm established for use with exemplary systems for delivering therapeutic nitric oxide gas to a patient, according to exemplary modalities of the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to systems and methods for compensating for long-term drift sensitivity in electrochemical gas concentration sensors used in a controlled environment, such as in systems for delivering therapeutic nitric oxide (NO) gas to a patient. To compensate for long-term drift sensitivity P LO L Ln / I 7n7 / E / Yl· In electrochemical gas sensors used in systems for delivering therapeutic NO gas to a patient, the systems and methods of the present invention sometimes utilize a calibration process such that the factors in the changes in the set dose of NO delivered to the patient are taken into account. The calibration process can initiate a plurality of baseline calibrations of the electrochemical gas sensor, where the frequency of the baseline calibrations is sometimes based on the magnitude of the change in concentration of the set dose (i.e., the absolute change in concentration from an initial set dose to a final set dose). This can result in compensation for sensitive changes in the electrochemical gas sensor. This sensitivity to long-term drift can be specific to sensors in atypical use, as, for example, the sensor may be exposed to substantially high NO concentrations (e.g., an order of magnitude higher than that observed during typical use) and / or this exposure may be for considerably longer durations (e.g., several orders of magnitude longer than during typical use), such as when the sensor is subjected to continuous operation associated with inhaled NO therapy. Furthermore, the sensor may be subjected to localized effects such as, but not limited to, temperature changes, chemical changes, humidity, electrolyte conductivity, and / or changes in internal physical resistance, to name a few.Therefore, the systems and methods of the present invention compensate for this long-term drift that may be specific to the sensor being used in an atypical way, for example, by using, among other things, calibration processes. Furthermore, the systems and method of the present invention can take into account actions occurring within the therapeutic NO gas delivery system and / or aspects of the surrounding environment before performing a baseline calibration and, at least in some cases, can respond accordingly. In at least some cases, this may result in a postponement of the baseline calibration and / or the rejection of using the sensor output for baseline calibration. Delivery and general sampling system Referring to Figures 1A-1B, exemplary therapeutic gas delivery systems (e.g., including an electrochemical gas sensor) for delivering therapeutic gas to a patient are shown for illustrative purposes. It is understood that catalytic-type electrochemical gas sensors and / or any teachings of the present invention may be used in any applicable system for delivering therapeutic gas to a patient. For example, the systems and methods of the present invention may be used, modified, and / or related to the delivery systems and / or other teachings of the patent of P LO L Ln / L7A7 / B / YL United States Patent No: 5,558,083 entitled NO Delivery System and / or U.S. Patent No: 5,752,504 entitled System for Monitoring Therapy During Calibration, the contents of both are incorporated herein by reference in their entirety. Electrochemical gas sensors, systems for delivering therapeutic gas to a patient, and systems and methods are sometimes described as being directed toward ON. For example, the electrochemical gas sensor is sometimes described as a nitric oxide sensor, NO sensor, or similar; the therapeutic gas delivery system is sometimes described as a therapeutic nitric oxide delivery system, therapeutic NO delivery system, nitric oxide delivery system, NO delivery system, or similar; and / or the therapeutic gas is sometimes described as nitric oxide, NO, or similar. This is merely for ease of use and is in no way intended as a limitation. Of course, the teachings described herein may, where appropriate, be applied to other therapeutic gases. In exemplary embodiments, a therapeutic gas delivery system 100 can be used to deliver therapeutic gas, such as NO, to a patient 102 who may be using a respiratory support device, such as a ventilator 104 or other device used to introduce therapeutic gas to the patient, for example, a nasal cannula, endotracheal tube, face mask, or the like. For ease of use, systems and methods of the present invention are sometimes described as being for use with a ventilator. This is merely for ease of use and is in no way intended as a limitation. The therapeutic gas can be supplied from a therapeutic gas source 103. The therapeutic gas source 103 can be any therapeutic gas source, such as a therapeutic gas contained in a cylinder (for example, a cylinder containing NO), a NO gas generator, or the like. Of course, other therapeutic gas sources may be used. The therapeutic gas delivery system 100 may include, among other things, a gas delivery subsystem(s) 105 and / or a gas sampling system 106. The therapeutic gas delivery system 100 may also include user input interface(s) 107(a) and / or display(s) 107(b), which may be combined, including a display and a keyboard and / or buttons, or may be a touchscreen device. The user input interface 107(a) and / or the display 107(b) may receive desired parameters from the user, such as the patient's prescription (in mg / kg of ideal body weight, mg / kg / hr, mg / kg / breath, mL / breath, cylinder concentration, delivery concentration or set dose, duration, etc.), the patient's age, height, sex, weight, etc.The user input interface 107(a) and / or the display 107(b) can, in at least some instances, be used to confirm the desired patient dosage (e.g., the user's desired dose input of NO in ppm) using a gas sampling system 106. P LO L Ln / ί7Π7 / Β / ΥΙ It is understood that any of the elements of system 100 can be combined and / or separated. For simpler elements, these are sometimes described as specific to subsystems. This is merely for the sake of simplicity and is in no way intended as a limitation. To deliver at least the desired, predetermined doses of therapeutic gas to a patient and / or to deliver a sample of therapeutic gas to a patient, the Therapeutic Gas Delivery System 100 may include a system controller comprising one or more processors and memory, wherein the system controller may be, for example, a computer system, a single onboard computer, one or more application-specific integrated circuits (ASICs), or a combination thereof. The processors may be coupled to memory and may be readily available in one or more memories, such as random-access memory (RAM), read-only memory (ROM), flash memory, a compact / optical disc, hard disk, or any other form of local or remote digital storage.Support circuits can be coupled to processors to support processors, sensors, valves, sampling systems, application systems, user inputs, displays, injector modules, breathing apparatus, etc., in a conventional manner. These circuits may include a cache memory, power supplies, clock circuits, input / output circuits, analog-to-digital and / or digital-to-analog converters, subsystems, power controllers, signal conditioners, and the like. Processors and / or memories can communicate with sensors, valves, sampling systems, management systems, user inputs, displays, injector modules, breathing apparatus, etc.Communication to and from the system controller can be via a communication path, where the communication path can be wired or wireless and where appropriate hardware, firmware and / or software can be configured to interconnect components and / or provide electrical communication plus communication paths. Clock circuits may be internal to the system controller and / or provide a time measurement relative to an initial startup, for example, during startup. The system may include a real-time clock (RTC) that provides real-time information, which may be synchronized with a maintenance time source, such as a network. Memory may be configured to receive and store values ​​for calculations and / or comparison with other values, for example, from sensor(s), pumps, valves, etc. In exemplary cases, memory can store a set of machine-executable instructions (or algorithms), which are executed by processors. P LO L Ln / ί7Π7 / B / YI may cause the sampling and / or delivery system to perform various procedures and operations. For example, the delivery system may perform a method to, for example, deliver a desired set dose of therapeutic gas (e.g., NO concentration, NO ppm, etc.) to a patient in need thereof, comprising: receiving and / or determining a desired set dose of therapeutic gas to be delivered to a patient, for example, which may be entered by a user; measuring the inspiratory flow of a patient breathing circuit; delivering therapeutic gas containing NO to the patient during inspiratory flow; monitoring inspiratory flow or changes in inspiratory flow; and varying the quantity (e.g., volume or mass) of therapeutic gas delivered in a subsequent inspiratory flow. In another example, the sampling system may perform a method for, for example, determining the target gas concentration (e.g., NO) being delivered to a patient, comprising: actuating a sampling pump and / or opening a gas sampling valve (e.g., three-way valve, etc.) to obtain a gas sample from the inspiration limb of a patient breathing circuit; the gas sample mixed with air and the therapeutic gas (e.g., NO) being delivered to a patient; exposing the gas sample to gas sensors (e.g., catalytic-type electrochemical sensors); obtaining sensor information indicative of the target gas concentration (e.g., NO, nitrogen dioxide, oxygen) being delivered to the patient; and communicating the target gas concentration to the user. In another example, the sampling system may perform a method to, for example, perform calibrations (e.g., baseline calibrations) of the gas sensor (e.g., catalytic type sensor, electrochemical gas sensor, NO sensor, etc.) comprising: actuating a sampling pump and / or opening a gas sampling valve (e.g., three-way valve, etc.).to obtain a sample of ambient air gas (e.g., air-conditioned environment); expose the ambient air gas sample to gas sensors (e.g., electrochemical catalytic NO gas sensor); obtain sensor information indicative of the target gas concentration (e.g., NO) in the ambient air (e.g., 0 ppm NO); and generate a new calibration line and / or modify an existing calibration line, e.g., replace the initial and / or previous information indicative of zero target gas concentration (e.g., 0 ppm NO) with the obtained information indicative of the target gas at zero ppm and use the slope of the initial and / or previous calibration line (e.g., the slope of the initial and / or previous calibration line connecting to the initial and / or previous zero calibration points). Machine-executable instructions may P LO L Ln / L7A7 / B / YL also include instructions for any of the other methods described in this document. In another example, the sampling system may employ a method to, for instance, select a gas source that has a zero concentration of the target gas, which may be ambient air at a substantially similar humidity and temperature to that of the breathing circuit gas. Overview of the Delivery Subsystem The gas supply subsystem 105 may include, but is not limited to, a gas delivery pressure sensor(s) 109; supply flow control valves 111, 113 and 115; a supply gas flow sensor(s) 117; a supply gas flow restrictor(s) 119; memory(s) 143; and a processor(s) 145. In examples of this modality, the gas delivery subsystem 105 can provide therapeutic gas, at a desired set dose (e.g., a desired concentration), to a patient. For example, the gas delivery subsystem 105 can mix the uncontrolled therapeutic gas stream (e.g., NO, etc.) into the patient's breathing gas in circuit 126, connected to ventilator 104, as a percentage of the patient's breathing gas. At least the flow rate of the uncontrolled therapeutic mixture gas (e.g., NO, etc.) is required.) in the patient's breathing gas, the gas supply subsystem 105 may include and / or receive NO from the NO source 103, for example, through a transport pipe 121 which may also be in communication with a fluid with an injector module 123, which in turn may also be in communication with a fluid with the inspiratory part of the circuit 126 which is affiliated with ventilator 104 for breathing. As used in this document, proportional uncontrolled mixing stream, uncontrolled mixing stream, and similar terms refer to the mixing stream, where the main flow stream is an uncontrolled (unregulated) flow known as the uncontrolled stream, and the component to be introduced into the uncontrolled stream is controlled as a percentage of the main stream, which can typically be mixed upstream (or alternatively downstream) of the main stream flowmeter. In various configurations, the inspiratory flow may be the uncontrolled stream since the flow is not specifically regulated or controlled, and nitric oxide is the mixing component delivered as a percentage of the inspiratory flow through a delivery tubing. The ventilator 104 can deliver breathing gas to patient 102 through inspiration branch 127 of the patient breathing circuit 126, while the patient's expiration can flow through an expiration branch 129 of the breathing circuit of the P LO L Ln / L7A7 / B / YL patient 126, sometimes, to the ventilator 104. With the injector module 123 coupled to an inspiration branch 127 of the breathing circuit 126, NO can be delivered from the gas supply subsystem to the injector 105 of module 123, through the supply line 121. This NO, then, can be delivered, through the injector module 123, into the inspiration branch 127 of the breathing circuit of the patient 126 affiliated ventilator 104 used to deliver the breathing gas to a patient 102. To regulate the flow of NO through supply line 121 to injector module 123, and in turn to patient 102 receiving breathing gas from inspiration branch 127 of the breathing circuit of patient 126, the therapeutic gas delivery system 100 may include one or more flow control valves 111, 113, and 115 (e.g., proportional valves, binary valves, etc.). For example, with flow control valves 111, 113, and / or 115 open, NO can be delivered to patient 102 by flowing through supply line 121 to injector module 123, and in turn into inspiration branch 127 of the breathing circuit of patient 126 and patient 102. In at least some cases, delivery system 100 may include one or more therapeutic gas flow sensors 117 that can measure the flow of therapeutic gas through flow control valves 111, 113, and 115 and / or delivery line 121, in turn allowing measurement of the therapeutic gas flow to injector module 123 and, subsequently, to the patient 102. Furthermore, in at least some cases, the injector module 123 may include one or more breathing circuit gas (BCG) flow sensors 131 that can measure and communicate to the delivery system the mass and / or volume flow rate(s) of breathing gas from at least the inspiratory line of the patient's breathing circuit that passes through the injector module 123 and, subsequently, to the patient 102. Although shown as being in injector module 123, the BCG flow sensor 131 may be placed in other parts of the inspiration branch 121, such as upstream of injector module 123.In addition, instead of receiving flow information from the BCG 131 flow sensor, the delivery system can receive flow information directly from the ventilator 104 indicating the breathing gas flow of the ventilator 104. In exemplary modalities, the therapeutic gas flow (e.g., no gas flow) may involve a proportional mixing of uncontrolled flow (also known as a metric ratio) (e.g., air) to the breathing gas to provide a desired set dose concentration of the therapeutic gas (e.g., NO) in the combined breathing and therapeutic gas. For example, a user may input a desired set dose, and the delivery system may deliver this set dose to patient 102. Furthermore, no delivery system 100 may perform, for example, through machine-executable instructions, a calculation of the delivered concentration that confirms that the P LO L Ln / L7A7 / B / YL The desired concentration of therapeutic gas (e.g., NO) is in the combined breathing gas and therapeutic gas using the known concentration from the therapeutic gas source 103; the amount of breathing gas flow in the patient circuit using information from the BCG flow sensor 131 and / or ventilator 104; and the amount of therapeutic gas flow in the delivery line 121 to the injector module 123 (and in turn with the patient 102) using information from the therapeutic gas flow sensor 117. In exemplary configurations, the therapeutic gas delivery system 100 can allow a user to input a target dose of the desired therapeutic gas (e.g., NO in ppm), and the therapeutic gas delivery system can confirm that the target dose of the therapeutic gas is being delivered to the patient by calculating the delivery concentration (e.g., as described above), as well as using the gas sampling system 106 to confirm the target dose of the therapeutic gas (e.g., NO) being delivered to the patient. In some cases, a problem may arise where the NO sensor does not accurately report the therapeutic gas dose being delivered to the patient. Overview of the gas sampling subsystem The gas sampling system 106 may include, but is not limited to, numerous sensors such as, but not limited to, an electrochemical NO gas sensor 108, which may have a catalytic electrode-type material with high catalytic activity for the sensor's electrochemical reactions, a catalytic-type electrochemical nitrogen dioxide gas sensor 110, and a galvanic-type electrochemical oxygen gas sensor 112, to name a few; a sample gas flow sensor(s) 114; a sample pump(s) 116; a sample system valve(s) 118; a processor(s) 120; and memory(s) 122. The sensors 108, 110, and 112 may be in series and / or parallel and / or in any order. For ease of illustration, the sensors 108, 110, and 112 are represented as being in series. This is merely for ease of use and is in no way intended to be a limitation.In various forms, the NO sensor can be an electrochemical sensor, which may comprise two electrodes, including a sensor and a counter electrode, separated by a thin layer of electrolyte. In example modes, the gas sampling subsystem 106 can sample and / or measure the concentration of different gases delivered to a patient. The concentration of NO delivered to the patient 102 can be included in the sample and exposed to the NO sensor 108, which in turn can provide output information indicative of the NO concentration in the breathing gas (e.g., NO ppm). For example, a sample of the gas supplied to the patient can be sampled through a sample line 124 located in P LO L Ln / ί7Π7 / E / YΙ fluid communication with the inspiratory duct 127 of the breathing circuit 126 affiliated with a breathing equipment 104. This gas sample from the inspiratory line 127, through the sample line 124, can flow and / or be pushed to the gas sensors (e.g. NO sensor 108). The flow in the sample line 124 can be regulated via valve 118 and / or sampling pump 116. Examples of mass or volumetric flow lines can be measured using flow sensor 114. The sampling line 124 can also be in fluid communication with a gas sample conditioner 128 which can condition the sample gas, for example, by extracting fluids, bringing the sample to the appropriate humidity, removing contaminants from the sample, and / or can condition the sample gas in any other way as desired. In exemplary configurations, the gas sampling system 106 can perform calibrations (e.g., baseline calibrations, range calibrations, etc.) of the gas sensor (e.g., a catalytic-type electrochemical gas sensor) by sampling and / or measure the concentration of target gases from a controlled sample (e.g., a reference sample, a calibration sample, etc.), where a calibration sample is a target gas (i.e., nitric oxide) with a specific and known concentration controlled within a range of interest (e.g., 10 ppm, 25 ppm, 50 ppm, 80 ppm, etc.) and / or where a baseline sample is a gas containing zero concentration of a target gas (i.e., ambient air containing zero nitric oxide). For example, an ambient gas sample 130 and / or a calibration gas sample 132 can be sampled through a sample line 134.This sample of ambient gas 130 and / or calibration gas 132, through sampling line 134, can flow and / or be pushed to the gas sensors (e.g., NO sensor 108). The flow in sampling line 134 can be regulated by valve 118 (e.g., a three-way valve, etc.) and / or flow sampling pump 116. The sampling line can be measured using flow sensor 114. In exemplary configurations, the sample line 134 can also be in fluid communication with a gas sample conditioner 136, which can condition the sample gas, for example, by extracting fluids, bringing the sample to the appropriate humidity, removing contaminants from the sample, and / or conditioning the sample gas in any other desired manner. For example, the ambient air (e.g., ambient gas 130) used for baseline calibration can be scrubbed of any unwanted gases using a scrubbing material. As an example, this scrubbing material can be a potassium permanganate scrubbing line, a material capable of scrubbing ambient air by removing NO and NO2. With NO and NO2 removed from the ambient air, the scrubbed air can be used for zero calibration since these undesirable gases have been removed and are therefore at 0 ppm. If necessary, a similar technique P LO L Ln / ί7Π7 / E / YΙ (for example, using an online washing material) can be done for a calibration gas. Sensor overview In exemplary embodiments, the electrochemical gas sensor used in the therapeutic gas delivery system 100 can be a catalytic-type three-terminal electrochemical gas sensor and / or a catalytic-type four-terminal electrochemical gas sensor. An example of a catalytic-type three-terminal electrochemical gas sensor 200 is illustrated in Fig. 2A, and an example of a catalytic-type four-terminal electrochemical gas sensor 200' is illustrated in Fig. 2B. Generally speaking, both catalytic-type three-terminal and four-terminal electrochemical gas sensors include a sensing electrode 202 (anode or working electrode) and a counter electrode 206 (cathode) separated by an electrolyte layer 208.In addition, these sensors may also include a capillary diffusion barrier 210, which can be used to control the reaction rate of the gas in the sensor (e.g., the reaction with the sensing electrode), and / or a hydrophobic barrier 212, which can be used to prevent the aqueous liquid electrolyte from escaping the sensor or drying out due to water vapor loss. When in use, the gas flowing into the sensor passes through a capillary diffusion barrier 210, diffuses through a hydrophobic barrier 212, and subsequently reaches and reacts with the sensing electrode 202. The gas sensor can be exposed to samples of the therapeutic gas, ambient gas, and / or calibration gas. The gas arriving at sensor electrode 202 reacts on the surface of the sensor electrode 202 through an oxidation or reduction mechanism catalyzed by the electrode materials specifically selected for the gas of interest. In other words, when oxidation occurs at the sensor electrode 202 (anode), reduction occurs at the counter electrode 206 (cathode), and a current is created. Positive ions flow toward the cathode, and negative ions flow toward the anode. Gases such as oxygen, nitrogen dioxide, and chlorine, which are electrochemically reducible, can be detected at the cathode, while those that are electrochemically oxidizable, such as carbon monoxide (NO) and hydrogen sulfide, can be detected at the anode.Connecting a resistor and / or current to a voltage amplifier 214 through the electrodes (sensing electrode 202 and counter electrode 206) generates an electric current proportional to the gas flow concentration between the anode and cathode (sensing electrode 202 and counter electrode 206). This current can be measured to determine the gas concentration. Because a current is generated in the process, these sensors can be described as amperometric gas sensors, micro fuel cells, and / or similar devices, to name a few. P LO L Ln / I 7Π7 / E / Y1ι In some cases, the electrochemical sensor 200 may also include a third electrode (e.g., three-terminal electrochemical sensors), as illustrated in Fig. 2A, which can act as a reference electrode 216. In electrochemical sensors that include a reference electrode, the sensing electrode 202 can be maintained at a fixed potential relative to the reference electrode (from which no current is drawn) so that both the reference electrode and the sensing electrode maintain a substantially constant voltage potential (e.g., maintained by a current source counter). This constant electrical potential ensures selectivity for the target gas or prevents cross-sensitivity to other non-target gases. In other cases, the electrochemical sensor 200 may include a fourth electrode (e.g., a four-terminal electrochemical sensor), as illustrated in Fig. 2B, which can act as an auxiliary electrode 218. This auxiliary electrode 218 can be used to subtract changes in output sensitivity unrelated to the concentration of the target gas that may be due to local effects in the electrochemical sensor 200. An electrochemical sensor 200 can be connected or installed in a suitable connection, where the wiring or connection can provide for or allow the detection of the number of electrodes (e.g., by the presence or absence of a voltage or current to or from the electrode). Drift sensor In exemplary configurations, catalytic electrochemical sensors (e.g., NO sensors, three-terminal electrochemical sensors, four-terminal electrochemical sensors, etc.) operate by reacting with the gas of interest (e.g., target gas, NO, etc.), producing an electrical current that is generally proportional to the concentration of the gas of interest. For example, the higher the concentration of NO reacting with the NO sensor, the greater the electrical current produced by the sensor. Therefore, using this proportional relationship, the electrical current produced by the sensor can be used to determine the concentration of the NO gas being sampled and / or delivered to the patient. Following the example of therapeutic NO gas delivery, the NO concentration can be determined and provided to a user using the NO sensor output, for example, on the user display. This allows the user to confirm that the set dose (e.g., the desired NO concentration) is actually being delivered to the patient. As noted earlier, the concentration of therapeutic gas (ON) in the inspiratory flow being delivered to the patient can be calculated, for example, using delivery concentration calculation; however, sometimes this calculated gas concentration The therapeutic NO output is displayed to the user. Accordingly, the sensor output may not be the only, or preferred, way for the user to confirm the correct therapeutic dose actually being delivered to the patient; drift in the NO sensor can be particularly problematic. Another specific challenge in therapeutic gas delivery is that NO is present in the conventional use of catalytic NO sensors (e.g., stack emissions monitoring), where sample flow rates from the breathing circuit must be kept to a minimum to avoid interfering with ventilation therapy (e.g., less than 250 mL / min, which can sometimes be lower than the minimum value specified by the electrochemical cell manufacturer). Sample gas flow rates can appear as leaks in the circuit from the perspective of ventilation therapy (e.g., the ventilator). When the therapeutic NO gas monitor is sampling from the breathing circuit, the reported inspiratory flows (and volumes) are higher than the measured expiratory flows (and volumes).This is known as inspiratory / expiratory volume mismatch; the patient may not receive the specified tidal volume. For ventilators with spontaneous ventilation modes (e.g., actively detecting and supporting the patient's inhaled effort), sample gas flow rates can interfere with breath-sensing algorithms and / or breath-sensing sensitivity. These ventilators monitor expiratory flows, which are lower than inspiratory flows, to detect breaths. When a sample gas flow rate is drawn from the inspiratory limb of a breathing circuit, the resulting expiratory flow measurement is lower than the inspiratory flow. All of the effects described above can impact the patient's ventilation therapy and lead to confusion for the caregiver. Referring to Figures 1A-1B and 3, due to this proportional (almost linear) relationship, a two-point linear interpolation calibration line 300 can be established where the sensor's electrical output range corresponds to a range of gas concentrations, including concentrations of 0 ppm. This calibration line can be established by exposing the NO sensor 108 to two known gas sources, such as one containing zero of the target gas, for example, an ambient gas source 130, and the calibration source 132 containing a known concentration of the target gas. For ease of reference, the ambient gas source 130 and the source 132 are depicted as being in continuous communication with the sample line 134. This is purely for convenience and is in no way intended as a limitation.For example, the ambient source 130 and / or the calibration source 132 can be in fluid communication with the sampling line 124. When using ambient source 130, an initial reference signal (also known as. The calibration point 302 can be determined by exposing the NO sensor 108 to an ambient gas source 130 (e.g., conditioned environment that may have 0 ppm of NO and / or that may be at ambient temperature and humidity) to establish an output current for a zero concentration of a target gas of interest (e.g., approximately 4.5 microamperes of output current for 0 ppm of NO). Using a calibration source 132, an extension calibration point 304 can be determined by exposing a NO sensor 108 to a calibration source 132 (e.g., calibration gas) to establish an output current for another known concentration (calibration concentration) of a target gas of interest (e.g., an output current of approximately 17 microamperes for 50 ppm of NO).The calibration connection point 304 and the zero point 302 establish a linear calibration line 300 for the sensor, allowing a user to determine the gas concentration based on the sensor's output current of NO 108. Additional points can be determined using a similar technique, and / or other known techniques can be used to produce a baseline calibration line. The sensor output values ​​for the different calibration points can be stored in memory. The linear calibration curve 300 can be stored in memory as an intercept value for the zero point 302 and a slope calculated from the zero point and the calibration point 304, or as a set of multi-point calibration values ​​304 of different concentrations and a zero point 302. However, during extended periods of continuous use, drift (offset) can occur in the output current set on the initial calibration line (e.g., initial baseline calibration, baseline current, initial calibration, etc.). In at least some cases, drift can occur due to, among other things, saturation of the catalytic-type electrochemical cell. This drift can cause the output to be displayed incorrectly to the user, for example, on display 107(b). In turn, the user may be unable to confirm that the desired set dose is actually being delivered to the patient. This can lead to numerous problems and confusion. For example, with an incorrect amount displayed on display 107(b), the user may believe that the incorrect concentration shown on display 107(b) is the actual concentration being delivered to the patient.Based on this incorrect information, the user may adjust the set dose (e.g., NO ppm) and therefore the concentration (e.g., of NO) delivered to the patient. This new, adjusted concentration could then be an incorrect dose for the patient, even though the displayed dose may indicate that the amount delivered is the desired set amount. P LO L Ln / L7A7 / B / YL De-saturation To correct for this drift, the sensor can be exposed for an extended period (e.g., hours, 24 hours, etc.) to ambient air and / or a source containing zero concentration of the target gas, allowing the sensor to desaturate. As the sensor slowly desaturates, its original sensitivity gradually returns. After desaturation, the original calibration line can be used more frequently, and in some cases, a new baseline calibration can be performed to generate a new calibration line. Although sensor desaturation can be used to correct drift, the extended period required to desaturate the sensor may not be acceptable for a NO sensor used in a therapeutic gas delivery system, as, for example, the sensor will be offline during the desaturation period. Zero and baseline calibration In exemplary modes, unlike sensor desaturation, baseline calibration and / or baseline drift compensation can be performed while the sensor is still at least partially saturated. Using this baseline calibration output, a new drift-compensating calibration line can be generated while the sensor is still at least partially saturated. To perform a baseline calibration, the sensor needs to be exposed to a reference source (e.g., a tank containing a known concentration of the target gas, a can of 50 ppm NO gas, etc.), and to perform a baseline calibration, the sensor needs to be exposed to a gas source containing zero concentration of the target gas (e.g., ambient air containing no target gas). The baseline calibration process can be more labor-intensive than baseline calibration, as it requires a container with a known concentration of the target gas, whereas baseline calibration can use ambient air (e.g., conditioned room air). In light of the above, baseline calibration may be more desirable to, among other things, reduce system complexity, minimize the device's footprint (e.g., in critical care areas, areas where the footprint is costly or a concern, etc.), and / or simplify system use.Consequently, in exemplary modalities, to compensate for baseline drift, either automatically and / or manually, a baseline calibration can be performed to generate a new calibration line that compensates for drift in the electrochemical sensor, for example, when the sensor is at least partially saturated. P LO L Ln / ί7Π7 / Β / ΥΙ In exemplary modes, a new calibration line that compensates for at least partially saturated sensor drift can be generated using the sensor output for a new baseline calibration and the slope of the initial and / or previous calibration line. The sensor drift can be the difference between the output of the new baseline calibration (306) and the initial and / or previous baseline calibration (302). For example, the amount of this drift (offset) from the current initial baseline (302) (4.5 microamperes for 0 ppm NO) to a new current baseline (306) (-1.0 microamperes for 0 ppm NO) can be determined when the sensor is exposed to 0 ppm NO (e.g., conditioned ambient air). Applying the slope of the initial and / or previous calibration line to the new baseline current, a new calibration line (308) can be generated.This new drift-compensating calibration line can then be used to determine the target gas (ON) concentration being delivered to the patient. In exemplary configurations, reducing the time required to perform a calibration (e.g., using the calibration program described in more detail below) can be important because it minimizes the downtime of the monitoring system. In at least some cases, some gas concentration alarms (high / low, no alarms, low / high O2 alarms, high NO2 alarms, etc.) can be inactive during this time. At least some alarms can be inactive during baseline calibration to avoid false and / or nuisance alarms.Accordingly, in exemplary modalities, the time to perform a baseline calibration and / or offline time may include both the response time of the catalytic-type electrochemical sensor required to obtain zero from the offset reading (e.g., the indicative output of 0 ppm when the sensor may be at least partially saturated) and the response time of the catalytic-type electrochemical sensor back to the set dose (e.g., the time required for the sensor to provide the target gas concentration when exposed to the target gas at the set dose).When calibrations are being performed and / or alarms are offline, an indicator can be provided to a user to inform them that calibration is being performed and / or alarms are currently offline, so that users do not mistakenly conclude that the system is not functioning properly. In exemplary modalities, the amount of this drift (offset) at the baseline (zero) current output can be determined by exposing the sensor (e.g., NO sensor) to a known concentration of 0 ppm of the gas of interest (e.g., NO), for example, using room air for a period of time (e.g., 3 minutes, etc.), where the time period can be in the range of approximately 3 to 5 minutes. CLOLLn / LZnZ / E / Yli to reset to zero (e.g., within the calibration line of the therapeutic gas delivery system) and after this exposure period (e.g., to ambient air), the sensor may then require another period of time (e.g., 2 minutes, etc.), where the time period may be in the range of approximately 1 to 2 minutes to stabilize the target gas. This drift can then be used to adjust the calibration offset. As an example, to determine the amount of this drift (offset) in the initial baseline current output (4.5 microamperes for 0 ppm NO), a new baseline current of 306 (-1.0 microamperes for 0 ppm NO) can be determined when the sensor is exposed to 0 ppm NO (ambient air).The change in the now-established baseline (e.g., from 0 microamperes to -1 microamperes for 0 ppm NO) can be applied using the slope of the initial and / or previous calibration line to reflect the current NO gas concentration. In various configurations, calibration may take approximately 4 to 7 minutes, and / or the system may be offline for less than 10 minutes. In exemplary configurations, the time period the sensor is exposed to a known concentration of 0 ppm (e.g., ambient air) can be determined and / or based on variables such as, but not limited to, the sensor's reaction rate to the target gas (e.g., sensor reaction rate to air, sensor reaction rate to NO, etc.); the size of the physical device; the types of gas exchange in the cell; thermal impedance to the surrounding environment; humidity; the gas flow sampling frequency (e.g., which may be secondary), which can affect the output signal and the signal rise and fall times; and / or any combination thereof, to name a few. In various configurations, a gas sensor may be exposed to a gas for approximately 5 seconds to approximately 15 seconds, or approximately 5 seconds to approximately 10 seconds to obtain a reading. In exemplary configurations, the output of a sensor, which may be in microamperes, can be converted to a digital value (referred to as counts) by an analog-to-digital converter (ADC) circuit. The rate of change of the sensor's output can be monitored and compared to predetermined thresholds considered stable. To determine if the sensor output is stable, it can be monitored and / or recorded over a period of time, and the average, minimum, and maximum values ​​observed during this period are compared to determine the amount the sensor output has varied and / or how uniform the output is across the monitored and / or recorded data. For example, the ADC count per unit of time might be 1.5 to 2.5 ADC counts every 10 seconds. The ADC counts can have a sampling frequency. P LO L Ln / ί7P7 / B / YI (e.g., 10 measurements per second) and can be sampled over a specified time period (e.g., 10 seconds). For example, a current in microamperes can be converted into a corresponding number of counts over a sampling period of 0.1 seconds, and the counts generated over a period longer than 10 seconds are summed and averaged. The number of counts measured during a period can be stored in memory. If the sensor output (e.g., in microamperes or ADC counts) is outside the stable threshold during the tracking period, tracking can continue until the sensor output is within the stable threshold, e.g., a count variation of 1 ADC or less over a 10-second tracking period.It has been found that, in at least some cases, the sensor's response to changes in the concentration of the target gas (e.g., changes in the set dose of NO) can be faster in newer sensors and / or with smaller absolute changes in concentration (e.g., smaller absolute changes in the set dose). Consequently, in exemplary embodiments, the systems and methods of the present invention can be adapted to the different rates of change of the sensor output to minimize the duration of offline time. For example, the calibration program and / or algorithm for changing the response to the set dose, described in more detail below, can take into account the different rates of change of the sensor output, thus minimizing the duration of offline time (e.g., the duration of time the NO sensor is offline, etc.).The sensor signal may exhibit an asymptotic approach to a final value over time. By monitoring the sensor output for variations during monitoring and / or recording over a period of time, calibration can be completed when the sensor output is stable within the threshold, which can provide a value of 99% within the full signal. In some exemplary configurations, the duration of time that the catalytic electrochemical sensor is exposed to ambient air during baseline calibrations may need to be the same for all baseline calibrations within a calibration program. For example, all baseline calibrations in the same calibration program may be required to be performed for the same period of time, so that the sensor is exposed to the gas for the same duration each time a calibration is performed. For example, a gas sensor reading might be taken at the end of a 5-second exposure time for each baseline calibration. By taking a reading for the same exposure time each time a calibration is performed, the sensor has the same amount of time to respond and produce the same final value. The applicant's research found that when the sensor is exposed to ambient air (for example, by starting a (P LO L Ln / L7A7 / B / YL automatic calibration), the sensor output initially decreases substantially rapidly over a short period, reaching approximately 90% of its final value within the first 30 seconds of exposure. This timeframe can vary depending on the sensor's responsiveness, with the output reaching approximately 90% of its final value within the first minute or two of exposure. The output then slowly decreases (e.g., exponential decay) to baseline over a longer period (e.g., hours, days, weeks, etc.). This subsequent, slower decay over a longer period may be the time required for desaturation.However, for sensor drift compensation using baseline calibrations, the applicant found that the slower decrease in sensor output over a longer period may be less significant (e.g., than the substantially rapid initial decrease in sensor output) for determining the reference drift compensation. Given this rapid initial decrease in sensor output, in one example, the duration of sensor exposure to ambient air (e.g., zero baseline calibrations) may need to be the same for all, or at least some, of the zero baseline calibrations. Calibration program (Set dose change) Although baseline calibration can be used to compensate for drift, when using catalytic-type electrochemical sensors (e.g., NO sensors) in a therapeutic gas delivery system that delivers the therapeutic gas (e.g., NO) to a patient (e.g., over an extended period), such baseline calibrations may require the electrochemical sensor signal to go offline. As noted earlier, having the electrochemical sensor offline can be problematic. For example, when the sensor is offline, users (e.g., doctors, nurses, etc.) may be unable to monitor NO deliveries and / or adjust the NO delivery to a patient. Furthermore, a user may be shown a reading different from the expected set dose or no reading at all during this outage, which can cause concern or confusion.Conversely, if the sensor has not been reset to zero (e.g., baseline calibration, etc.), then the measured NO concentration may not be accurate. This can be problematic because, while it may be preferable from an accuracy standpoint to perform baseline calibrations very frequently, such frequent baseline calibrations may not be acceptable, at least from a therapeutic perspective, due to the system's capacity. P LO L Ln / L7A7 / B / YL Therapeutic gas supply using the electrochemical sensor is offline during baseline calibration. In at least some modalities, the electrochemical sensor may be disconnected for a period of time between 5 and approximately 10 minutes, or for a maximum period of 10 minutes during baseline calibration. Taking the above into account, the applicant conducted extensive research and found that the drift sensitivity of electrochemical gas cells can be related to the absolute change in the concentration of the therapeutic gas (e.g., absolute change in the set NO dose), where the greater the absolute change, the greater the amount of drift. Based on this relationship, the frequency of calibrations (e.g., baseline calibrations, etc.) performed on catalytic-type electrochemical sensors (e.g., NO sensors) can be reduced by factoring in the change in the absolute concentration of NO delivered to the patient (e.g., the change in the absolute concentration of the set NO dose).Therefore, a program (e.g., calibration program) that takes into account the change in the absolute concentration of NO administered to the patient (e.g., the change in the absolute concentration of the set dose of NO) can be used to ensure greater sensor accuracy while reducing the duration of time and / or the number of times the sensor is disconnected.Consequently, in exemplary modalities, the frequency of baseline calibrations in a calibration program can be based on the absolute change in the concentration of NO administered to the patient (e.g., absolute change in the set dose). Baseline calibrations may be more frequent (e.g., shorter intervals between baseline calibrations) for larger absolute changes in the concentration of NO delivered to the patient (e.g., absolute change in a set dose), and / or less frequent (e.g., longer intervals between baseline calibrations) for smaller absolute changes in the concentration of NO delivered to the patient (e.g., an absolute change in the set dose). The interval between calibrations may increase proportionally with an absolute change in the set dose.The duration of zero calibration done with ambient air or residual calibration may be negligible for changes in cell saturation or desaturation. Referring to Figs. 4-5, the demonstrative graphs illustrate the drift in the desired set dose (e.g., as shown to the user to confirm a precise dose of NO being delivered to a patient) and baseline calibrations, used as an example in a calibration program, of a sample four-terminal catalytic-type electrochemical gas sensor for NO over time for a patient who may actually be receiving the desired set dose. That is, the patient P LO L Ln / ί7P7 / B / YI may be receiving the correct set dose; however, the amount displayed to the user shows an incorrect delivered amount. For example, the demonstrative graph illustrated in Fig. 4 shows the drift and baseline calibrations for a patient receiving a set dose of 50 ppm NO, and the demonstrative graph illustrated in Fig. 5 shows the drift and baseline calibrations for a patient receiving a set dose of 25 ppm NO. It is understood that the patient dosage may remain at the desired set dose (e.g., set dose of 50 ppm NO, set dose of 25 ppm NO, etc.) even though the sensor reading may deviate (e.g., which in turn may be displayed to the user of a therapeutic gas delivery system as a different ppm being delivered to the patient).In various configurations, the type of electrochemical gas sensor can be programmed into memory, for example, by a user or through automatic detection by the system controller. In other configurations, the type of electrochemical gas sensor can be detected by controlling a potentiostat and sensing a change in voltage and / or current at an electrode, and / or by detecting the presence of a current or voltage at a probe in a socket configured for the sensor. In exemplary modalities, a recalibration program can be used to determine when baseline calibrations occur and / or is implemented in response to a change in the set dose, sometimes automatically. For example, the patient may begin receiving the set dose of NO at 50 ppm (e.g., as set by the user), thus exposing the NO sensor to 50 ppm of NO. However, as shown, drift begins in the sensor (e.g., indicating that the patient may be receiving a lower ppm dose than what was set and / or delivered to the patient). To correct this drift, a baseline calibration can be performed on the sensor after a desired amount of time (e.g., three, four, or six hours) of NO exposure.This interval can be measured using an internal clock or a real-time clock within the system controller or system, where the internal clock or real-time clock can be used to identify a time to perform a calibration. After performing a baseline calibration, the sensor can then be exposed to NO again. Subsequently, the sensor may begin to exhibit drift again. To correct this drift, a baseline calibration can be performed on the sensor again after another desired amount of time (e.g., six, eight, or twelve hours) of NO exposure. This interval can be measured relative to the previous interval using the internal clock or absolutely using the real-time clock to identify a time for the subsequent calibration.After performing the above baseline calibration, the sensor can resume after being exposed to NO at 50 ppm and again in the sensor can. P LO L Ln / I 7P7 / E / Y1ι to begin drift. To correct this drift, a baseline calibration can be performed on the sensor after another desired amount of time (e.g., twelve hours) of exposure to NO. In various embodiments of the present invention, the maximum interval between calibrations can be 24 hours, so that a minimum of one calibration is performed per day. In some exemplary configurations, the recalibration program(s) can be stored in the controller's memory. There can be one or more recalibration programs, where a calibration program comprises one or more values ​​indicating one or more time intervals between calibration operations. For example, a method for calculating a recalibration program might be based on 150 ppm-hours and include dividing 150 ppm by the set dose to determine the number of hours of the time interval between calibration operations. For example, if after a set dose of 50 ppm for 3 hours, 150 ppm-hours would have accumulated. If a new dose of 25 ppm is then set, a 6-hour accumulation (150 ppm-hours) would occur before another baseline calibration takes place. The intervals between subsequent calibrations can be twice the previous interval, up to 12 hours, and / or up to 24 hours later. In an exemplary mode, the ppm-hours (e.g., X ppm-hours) can be doubled (e.g., 2X ppm-hours) to calculate the interval until the second calibration, and doubled again to calculate the interval until the third calibration, and so on, until the maximum 24-hour calibration interval is reached. For example, 150 ppm-hours can be doubled to 300 ppm-hours to calculate the interval until the second calibration, and doubled again to calculate the interval until the third calibration, and so on, until the maximum 24-hour calibration interval is reached. For example, a change in the set dose from 10 ppm to 60 ppm would result in an absolute change of 50 ppm, so the interval between the change in the set dose and the first calibration would be 150 ppm-hours / 50 ppm = 3 hours.The next interval would be 300 ppm-hours / 50 ppm = 6 hours after the first calibration, as measured by the clock, followed by an interval of 600 ppm-hours / 50 ppm = 12 hours later. The next interval would be 1200 ppm-hours / 50 ppm = 24 hours later, which may also be the maximum interval, so no further calculations are performed, and each subsequent interval between calibrations remains 24 hours. The greatest amount of drift has been found to occur during the first 24 hours after a set dose change, and it deviates only slightly over a 24-hour period if the concentration is the same for that period. As noted above, in example modalities, calibration programs may take into account the absolute change in the set dose of NO that is delivered to the patient, where the largest absolute changes in the set dose P LO L Ln / ί7P7 / E / YI may require more frequent initial calibrations than smaller absolute changes, where, for example, a positive or negative change of 10 ppm has less impact than an interval between calibrations that has a positive or negative change of 50 ppm. As an example, Fig. 4 illustrates, among other things, an absolute change of 0 ppm of NO delivered to a patient at 50 ppm (and exposing an exemplary catalytic-type four-terminal electrochemical NO gas sensor to 50 ppm of NO), while Fig. 5 illustrates, among other things, at least one modality of an absolute change of 0 ppm of NO delivered to a patient at 25 ppm (and thereby exposing the exemplary catalytic-type four-terminal electrochemical NO gas sensor to 25 ppm of NO). As can be seen by comparing Fig. 4 and Fig. 5, with a larger absolute change in NO concentration (e.g., as shown in Fig.4) The drift is greater, and therefore baseline calibrations may be more frequent than for a smaller absolute change in NO concentration (e.g., as shown in Fig. 5). In various modes, the ppm-hour value may depend on the type of sensor installed and / or detected by the system controller, or it may be user-defined, for example. In some modes, the system may have a pre-set self-calibration program every 24 hours. Based on calculations using 150 ppm-hours, a 50 ppm change results in an initial calibration interval of 150 ppm / 50 ppm = 3 hours, as shown in Fig. 4. Of course, other ppm-hour values ​​are also considered. For example, based on calculations using 100 ppm-hours, a 25 ppm change results in an initial calibration interval of 100 ppm / 25 = 4 hours, as shown in Fig. 5. In some exemplary cases, the frequency of baseline calibrations in a calibration program, which may be based on the absolute change in NO concentration administered to the patient (e.g., a set dose), may also depend on whether the catalytic-type electrochemical sensor has three or four terminals. At least in some cases, four-terminal catalytic-type electrochemical sensors may have calibration programs that initially vary in the duration between baseline calibrations and then establish fixed durations between baseline calibrations. In at least some cases, three-terminal catalytic-type electrochemical sensors may have calibration programs with fixed durations between baseline calibrations. While it is not intended to be limited by theory, or to limit the scope of the invention in any way, it is currently believed that, although the auxiliary electrode in the catalytic-type four-terminal electrochemical sensor (e.g., NO sensor) may be intended to be used to cancel the localized effects seen in the sensing electrode that may produce and / or effect the output (e.g., electrical current, ADC counts, etc.) from the P LO L Ln / I 7P7 / E / Y1i The detection electrode does not provide any indication of the target gas concentration. When used atypically, the localized effects on the auxiliary electrode and the localized effects on the detection electrode may not follow the same principle. However, after prolonged exposure (e.g., 24 hours) to the same NO concentration (e.g., when the set dose remains constant), this difference between the auxiliary and detection electrodes may become negligible. In other words, when dose changes occur in a four-terminal catalytic-type electrochemical sensor array (e.g., without sensors), there may be an initial non-steady-state period, followed by a steady-state period. On the other hand, since a three-terminal catalytic-type electrochemical sensor (e.g., an NO sensor) does not include this auxiliary electrode, this effect does not occur.This is believed to be the reason why, for the same absolute change in NO, different calibration programs may be required for three-terminal catalytic electrochemical sensors and four-terminal catalytic electrochemical sensors. These localized effects may include, but are not limited to, temperature changes, chemical changes, humidity, and / or changes in the internal physical resistance when the first baseline calibration was applied to the device (e.g., these may be specific to atypical sensor use), to name a few. For example, as illustrated in Figures 4-5, along with baseline calibration intervals that vary with respect to the absolute change in the set dose, the calibration schedule for a catalytic-type, four-terminal electrochemical sensor may initially vary and then become fixed. As shown, along with baseline calibration intervals that vary with respect to the absolute change in the set dose, the baseline calibration intervals in the calibration schedule may initially vary (e.g., 3 hours, 6 hours, 12 hours; 4 hours, 8 hours, 16 hours, etc.) and then become fixed (e.g., 12 hours; 16 hours; etc.). In another example, as illustrated in Figs. 6-7, while the baseline calibration intervals vary with respect to the absolute change in dose, the calibration schedule for a catalytic-type, three-terminal electrochemical sensor can be fixed. As shown, while the baseline calibration intervals vary with respect to the absolute change in dose, the baseline calibration intervals in the calibration schedule can be fixed (e.g., 3 hours, 4 hours, etc.). The absolute change in the established dose of NO delivered to the patient shall be understood to refer to the absolute variation from zero ppm of NO (e.g., before delivery of therapeutic NO to the patient) to the initial established dose of NO and changes in the established dose (e.g., changes in the established dose during treatment). P LO L Ln / L7A7 / B / YL exemplary modes, calibration programs that take into account absolute changes in set doses can treat the absolute change in a set dose when the first treatment begins (e.g., initial set dose) as well as changes in the absolute set dose that occur during treatment. For example, the calibration program, illustrated in Fig. 8, for a catalytic-type four-terminal electrochemical sensor having an initial set dose of 25 ppm NO (e.g., an absolute change in set dose of 25 ppm NO) can be the same as the calibration program, as illustrated in Fig. 9, for the same catalytic-type four-terminal electrochemical sensor which has a set dose with a change from 40 ppm NO to 15 ppm NO (e.g., an absolute change in set dose of 25 ppm NO). In exemplary embodiments, the systems and methods of the present invention detect changes in the set dose (e.g., initial set dose, changes in the set dose during treatment, etc.), determine the absolute change in the set dose, and select and / or implement the appropriate calibration program based on the determined absolute change in the set dose. For example, in response to a user setting an initial set dose (e.g., to 50 ppm), the desired self-calibration program for that set dose can be selected, for example, automatically by machine-executable instructions. In another example, in response to a change in the set dose by a user (e.g., from 75 ppm to 25 ppm; from 25 ppm to 50 ppm; etc.).) the desired self-calibration program so that the absolute change in the set dose can be selected, for example, automatically by machine-executable instructions. Referring to Fig. 10, the therapeutic gas delivery system can perform at least some of the steps of the illustrated exemplary method, for example, automatically implementing the appropriate recalibration program in response to a change in the set dose. Table 1 illustrates and exemplifies a set of recalibration programs. As an example, an algorithm for changes in the response dose set 1000 stored in memory (memory affiliated with the therapeutic gas delivery system) may include machine-executable instructions that processors (processors affiliated with the therapeutic gas delivery system) can access and execute, for example, in response to a change in the set dose. This change in the set dose may be the initial set dose and / or a change in the set dose during the delivery of therapeutic gas to a patient.For ease of understanding, the following example distinguishes between a change from an initial set dose and a change in the set dose during the delivery of therapeutic gas to a patient. This is merely for ease of understanding. P LO L Ln / L7A7 / B / YL is in no way intended to be a limitation. A person with ordinary experience in the technique will recognize that a recalibration program can be generated by a formula or, as the case may be, an algorithm. P LO L Ln / ί7Π7 / Β / ΥΙ TABLE 1 Magnitude of change in dose adjustment (ppm) Time interval between calibrations (Hrs) 5 24 24 24 24 24 20 8 12 24 24 24 25 6 12 24 24 24 40 4 8 12 24 24 50 3 6 12 24 24 80 2 4 8 12 24 In step 1002, an initial selection dose can be entered (e.g., by the user) and / or an initial set dose value can be stored in memory (memory affiliated with the therapeutic gas delivery system controller). Since this is the initial set dose value, the previous set dose value can sometimes be assumed to be zero. In some cases, the user may have previously been receiving a set dose, for example, from another therapeutic gas delivery system. For these situations, the previous set dose value is entered (e.g., via the user interface) so the user can know what the previous set dose was (e.g., delivered by another therapeutic gas delivery system to the patient), and this information can be stored in memory (memory affiliated with the therapeutic gas delivery system).Furthermore, for this type of situation, the therapeutic gas delivery system can communicate (for example, through a communication portal affiliated with the therapeutic gas delivery system) with the other therapeutic gas delivery system (for example, the previous therapeutic gas delivery system that delivers therapeutic gas to the patient) and the dose value of the previous group (for example, the previous set dose that was being delivered to the patient) can be communicated (for example, through an associated communication portal (operationally associated) with the therapeutic gas delivery system) and stored in memory (memory affiliated with the controller of the therapeutic gas delivery system). In typical configurations, an initial self-calibration can be run to establish a baseline and to compensate for any drift during periods when the system may have been shut down (e.g., during storage, maintenance, NO container change, etc.). A user-defined initial dose input can then be used to determine the absolute change (i.e., from 0 ppm) and the self-calibration schedule. In situations where the gas supply system can be powered on and operating, but has a set dose of 0 ppm, a self-calibration can be performed every 24 hours. During this period of 0 ppm operation, the sensor may become desaturated, thus requiring drift compensation. In various configurations, upon startup of the therapeutic gas delivery system, the system may immediately initiate a default calibration (e.g., every 24 hours) and begin a baseline calibration after startup, but before allowing a user to enter a set initial dose. This ensures that the sensor is calibrated and an accurate baseline value has been stored in the system controller's memory. Such initial calibrations may be performed to reset the baseline and / or compensate for desaturation while the device is in storage, or when the therapeutic gas delivery system is restarted after a previous therapy session, and before the next therapy session. If a user attempts to run a pre-check during an automatic baseline calibration, the initial pre-use check system controller may automatically notify the user to delay patient delivery and surveillance performance testing until the automatic baseline calibration and any intended use are complete. In step 1004, the therapeutic gas delivery system controller can determine the absolute change in the dose set values, for example, by determining whether the absolute change in the dose value threshold set is met in step 1006, and / or by selecting a desired calibration program in step 1008. The absolute change in the prepared dose can be determined by calculating the absolute value of the previous set dose minus the new set dose. For example, processors (therapeutic gas delivery system affiliate processors) can access the previous set dose value (e.g., NO at 50 ppm, NO at 0 ppm, etc.) and subtract the new set dose (e.g., NO at 25 ppm, NO at 40 ppm, etc.) from the previous set dose. This determined absolute change in set dose can be made positive, if necessary.In various modalities, the established dose threshold can be 5 ppm of NO at the start of the determination and / or the selection of a recalibration program. In step 1006, the therapeutic gas delivery system controller can determine if a threshold value (e.g., 5 ppm of NO) has been encountered to initiate the selection and / or execution of the desired calibration program. This threshold value can be based on CLOLLn / LZnZ / E / Yli in a minimal change in the set dose and / or a cumulative amount of set dose delivered (e.g., ppm-hours), where the cumulative amount can be 150 ppm-hours. A threshold value to initiate the selection and / or execution of the desired calibration program may be included in the set dose response algorithm set 1000 such that if the absolute change in the set dose and / or quantity of the cumulative dose delivery system is below the threshold, the therapeutic gas delivery system may NOT select and / or implement a new calibration program and / or may store the new set dose value from memory, in the event of a subsequent change in the set dose and / or additional set dose delivered (e.g., to add to the cumulative amount of set dose delivered).Confirmation that the absolute change in prepared dose is above a threshold (e.g., 5 ppm) can be made as minor changes in the set dose and / or minor cumulative amounts of the set doses delivered may not require the selection and / or execution of a calibration program. For example, absolute changes in set dose that are less than 5 ppm cannot result in substantial drift; therefore, a change of 5 ppm or less will not initiate a recalculation or a new determination of a recalibration program. In another example, cumulative amounts of set dose delivered that are less than 100 ppm-hours (e.g., 20 ppm delivered over 5 hours) cannot result in substantial drift. In yet another example, combined cumulative amounts of set dose delivered that are less than 100 ppm-hours (e.g., 20 ppm delivered over 5 hours) and absolute changes in set dose that are less than 5 ppm cannot result in substantial drift. If the threshold is not met, the therapeutic gas delivery system may take no action, and if a change in set dose occurs, proceed to step 1012.If the threshold is met, the therapeutic gas delivery system can proceed to the selection and / or implementation of an appropriate calibration program. In modality examples, in step 1008, the processors can then select the appropriate calibration program for the determined absolute change in the sent dose value, for example, from the calibration programs stored in memory (memory affiliated with the therapeutic gas delivery system) based on the determined absolute change in the set of dose values. In step 1010, the selected calibration program can be implemented in the therapeutic gas delivery system, resulting in baseline calibrations performed (e.g., automatically) at intervals defined by the selected calibration program. For example, when the selected calibration program is implemented, the sampling system can perform a method to, for example, execute P LO L Ln / ί7Π7 / Β / YI baseline calibrations comprising: operating a sampling pump and / or opening a gas sampling valve (e.g., three-way valve, etc.).) to obtain a sample of ambient air gas (e.g., ambient air); expose the ambient air gas sample to gas sensors (e.g., catalytic electrochemical NO gas sensors) for a period of time; obtain sensor information indicative of the target gas concentration (e.g., NO) in the ambient air (e.g., 0 ppm NO); and generate a new calibration and / or modify an existing calibration line, e.g., replacing the initial and / or previous information indicative of zero ppm of the target gas with the obtained information indicative of zero ppm of the target gas and using the slope of the initial and / or previous calibration line (e.g., the slope of the initial and / or previous calibration line connecting the initial and / or previous zero and previous calibration points).The calibration line can be stored in the controller's memory as a zero intercept value from the baseline calibration and a slope from an initial calibration to provide the values ​​for the formula Y = mx + b, where m is the slope and b is the origin equal to zero. The calibration line can also be stored in the controller's memory as a table of data points over the calibration period, including the zero intercept. Changes in the zero intercept determined by baseline recalibration can then be used to correct the equation and / or the stored data points, thus representing the new calibration line. In step 1012, while the therapeutic gas delivery system is supplying therapeutic gas to the patient, the system can monitor and / or detect a change in the set dose. For example, the system can detect a change in the set dose based on user-initiated changes. If no change in the set dose is detected, the system can continue to monitor for a change and / or remain on standby. If a change in the set dose is detected, the system can perform the steps described in step 1004. Postponement of calibrations In one or more modes, calibration can be postponed for a period of time if an alarm is active at the time the calibration is scheduled to take place. The system controller can determine that an alarm is active and proceed to recheck for the presence of an alarm and / or delay the start of a calibration operation by a set time interval (for example, it can begin after the alarm stops) and recheck the alarm after the set time interval has elapsed. P LO L Ln / L7A7 / B / YL expired. In certain modes, the system controller can monitor the alarm and determine when it has stopped. At that point, the controller can delay self-calibration for a predetermined time, for example, to ensure the alarm does not reactivate. Additionally, the system controller can determine if an alarm has previously triggered within a predetermined time period before calibration runs. If an active alarm is detected, calibration can be postponed, and it can run if no active alarm is detected. The controller can also monitor for other offline activities and / or circumstances that might otherwise interfere with self-calibration and set a delay to allow for such circumstances to be resolved.The system controller can also detect if a user is interacting or has interacted with the therapeutic gas delivery system within a predetermined time frame at the time the calibration is run, where the calibration is postponed if the user is interacting or has interacted with the agent's therapeutic gas delivery system within the predetermined time frame and runs if the user is not interacting or has not interacted with the therapeutic gas delivery system within the predetermined time. In one or more modes, calibration may be postponed for a period of time if the user is interacting with the therapeutic gas delivery system at the time the calibration is scheduled to begin. Interactions may include, but are not limited to, user input, changing the therapeutic gas source, changing the sample gas conditioner, disconnecting the delivery system from an affiliated carrier, purging, etc. The system controller may determine that the user is interacting with the delivery system and continue to recheck for an alarm and / or delay the start of a calibration operation by a set time interval (e.g., after the last interaction ends) and recheck that the user interaction has ended after the set time interval. In one or more modes, a calibration may be postponed for a period of time if the sensor output during a baseline recalibration using ambient air indicates the presence of an interfering gas, such as H₂S, NO₂, etc. The interfering gas may originate from cleaning products, flatulence, a system leak, or other sources of contamination. In such cases, the recalibration is interrupted and / or rejected and rescheduled for 1.5, 10, or 15 minutes later to allow the ambient air to clear. In at least some cases, postponing a calibration may be necessary because the new baseline calibration based on the sensor output during this time period would not necessarily be indicative of sensor drift. P LO L Ln / L7A7 / B / YL and this can lead to the new calibration line being inaccurate. This can lead to improper dosing information being displayed to the user. In at least some cases, this sensor output is rejected to ensure it is not used for drift compensation. In various modes, the system controller can detect whether one or more interfering gases are causing or have caused the sensor output to be out of range within a predetermined timeframe at the time calibration is to be performed. Calibration is postponed if the sensor output is or has been out of range within the predetermined timeframe at the time calibration is to be performed, and it is performed if the sensor output is or is not out of range within a predetermined timeframe.In various modes, the system controller can detect if one or more interfering gases are causing or have caused a calibration postponement due to the detection of sensor output outside a threshold range within a predetermined time frame at the time the calibration is to be run, where the calibration can be postponed again if the sensor output is still out of range within the predetermined time frame at the time the calibration is to be run, and runs if the sensor output is not out of range within a predetermined time frame. In other exemplary modes, the system controller can determine when an interfering gas may affect the sensor because the sensor output may be outside the expected range due to drift (e.g., 0 ADC counts to 655 ADC counts). For example, the system controller can postpone calibration when the sensor output is greater than an expected output threshold. In at least some modes, the expected output threshold may be 0 ADC counts to 655 ADC counts, and when the sensor output is outside this expected output threshold, the system controller can postpone calibration for a period of time (e.g., 1, 5, 10, or 15 minutes). The sensor can then undergo calibration; however, if the sensor output again exceeds the expected output threshold, calibration may be postponed again.This can be repeated as needed, thereby ensuring that the interfering gas has been dispersed (e.g., by allowing the ambient air to be cleared). Calibration programs (quantity) In some exemplary modalities, there may be only one or a small number of calibration programs stored in memory (memory associated with the therapeutic gas delivery system). A limited number of calibration programs may be available for selection, for example, to conserve memory usage and / or reduce complexity. For instance, in at least some modalities, only one The calibration program P LO L Ln / i7P7 / B / YI can be stored in memory and / or selected to address the largest absolute change in the set dose seen under the vast majority of uses. Using this calibration program for this set dose (e.g., the largest seen most of the time) means that only this program will be available for selection in step 1008. This can be beneficial as memory usage and / or complexity can be reduced, while a calibration program can be implemented that addresses sensor drift while reducing the number and / or duration of sensor disconnections. For example, since the vast majority (e.g., 99%, etc.)The concentration of all therapeutic gas supplies may be less than a set dose of NO at approximately 50 ppm, and then using a calibration program based on an absolute change in set dose of 50 ppm addresses the worst-case scenario, as well as providing the benefit of reduced sensor offline time. Following this example, if the absolute change in set dose is, for example, 20 ppm, the calibration program used can be used for an absolute change in set dose of 50 ppm. Sample valve In exemplary embodiments, the gas sampling valve described above (e.g., valve(s) 118 illustrated in Figs. 1A-1B) may be a three-way valve in fluid communication with the gas sensors (e.g., NO sensor); the gas in the breathing circuit (e.g., through sampling line 124 illustrated in Figs. 1A and 1B); and the calibration gas, such as ambient air, which may be conditioned (e.g., through sampling line 134 illustrated in Figs. 1A and 1B).Using a three-way valve, when the valve is opened to the first position, the sensors can be exposed to gas samples in the breathing circuit, while the calibration gas flow is restricted. When the valve is opened to the second position, the sensors can be exposed to the calibration gas (e.g., a climate-controlled environment), while the sample gas flow from the breathing circuit is restricted. With this configuration, when performing a baseline calibration, the breathing circuit sampling line does not need to be disconnected from the breathing circuit and / or the therapeutic delivery system.Without such a configuration, users may be required to disconnect the breathing circuit sampling line from the breathing circuit and / or the therapeutic delivery system, which may be undesirable since, generally speaking, modifying the breathing circuit may increase the risk of damaging the circuit or components affiliated with it, increase the risk to the patient and / or the impact of the delivery of the therapeutic gas to the patient. P LO L Ln / L7A7 / B / YL In at least some cases, the systems and methods of the present invention can detect whether the gas sampling valve is functioning properly, for example, preventing incorrect calibration. This can be particularly important for baseline calibrations performed automatically when the user is not present to observe the gas sensor readings during calibration. In exemplary embodiments, the therapeutic gas delivery system can detect whether the gas sampling valve is functioning properly by monitoring the electrical current supplied to the sampling valves (e.g., the current draw when actuated, etc.) and / or by monitoring the flow and / or pressure in the sampling lines (e.g., sampling line 134 and / or sampling line 124 illustrated in Figs. 1A-1B, etc.).For example, if the therapeutic gas delivery system can detect that the gas sampling valve is functioning properly by monitoring the pressure and / or flow in the gas sampling line just upstream of the sampling pump, the pressure and / or flow in the line for receiving ambient and / or calibration samples (e.g., sampling line 134 illustrated in Fig. 1A) may be different from the pressure and / or flow in the line for receiving samples from the patient's breathing circuit (e.g., sampling line 124 illustrated in Fig. 1A). In various modalities, the ADC counts just before a calibration may be stored in temporary memory for comparison with the ADC counts during baseline calibration, where a negligible change in the ADC counts may indicate that the valve has not functioned correctly.When it is detected that the calibration is not working correctly, it can be postponed, retried, and / or cancelled. User notification In some models, the display may be blank during calibration to prevent the user from misinterpreting values ​​during calibration as a set dose reading. To avoid this confusion, a message indicating that calibration is in progress may be displayed to the user and / or logged in the electronic medical record (EMR) to inform the user of system activity. For example, the user may be informed that the concentration monitoring of inspiratory line 127 of breathing circuit 126 is currently offline, for example, by means of an appropriate message and / or an audible indicator. In some exemplary configurations, system alarms can be taken offline to prevent an alarm from being triggered due to a discrepancy between the set dose and the concentration measured by the sensor during calibration. This can be referred to as an alarm blackout. This alarm blackout can also cause confusion for a P LO L Ln / L7A7 / B / YL The user expects an alarm when the measured concentration (e.g., user sample) differs from the set dose. A message indicating that the alarm(s) have been deactivated during the calibration period (e.g., 5 to 10 minutes) may appear, thus informing the user appropriately. In some cases, the system can alert the user that a calibration has failed. This can occur if the valve is malfunctioning, or if multiple calibration sensor readings are displayed that fall outside the specified threshold values. The number of calibration retries (e.g., 4, 5, 6, etc.) before an error message is displayed can be user-selected or predefined and coded into the system controller or stored in memory. General description of drift As mentioned previously, while it is not intended to be constrained by theory, or to limit the scope of the invention in any way, it is currently believed that, although the auxiliary electrode and the sensing electrode are intended to be in nearly identical conditions, with the exception that the sensing electrode is exposed to the target gas (e.g., NO), while the auxiliary electrode is not, there appear to be localized effects that may cause the auxiliary electrode and the sensing electrode to not be in identical conditions, at least for an initial period of time. These localized effects may include, but are not limited to, temperature changes, chemical changes, humidity, and / or changes in the internal physical resistance when the first baseline calibration has been applied to the device (e.g., which may be specific to the sensor's atypical use), to name a few. Regarding chemical effects, it is believed that the electrolyte in catalytic-type electrochemical gas sensors (e.g., NO sensors) can be contaminated by oxides (e.g., nitrogen oxides from NO). This could be because the concentration of NO used may be substantially higher than the concentration of these oxides in sensors to which they are conventionally exposed, and / or because the duration of exposure of these sensors when used for therapeutic NO delivery may be substantially longer than the duration of exposure they experience when conventionally used for measuring toxic gas emissions. At least in some cases, this localized effect is believed to be the primary cause of the sensor drift observed when the sensor is used atypically. Regarding the effects of temperature, referring again to Fig. 2A, it has been found that the baseline signal of three-terminal electrochemical sensors used under continuous service tends to increase exponentially with time and the P LO L Ln / ί7P7 / B / YI temperature (e.g., approximately double for every 30°C increase in temperature). This change in the percentage of the signal relative to the change in temperature has been found to be similar between the baseline signal output and for a given target concentration. In electrochemical sensors that include an auxiliary electrode (e.g., four-terminal electrochemical sensors), the auxiliary electrode 218 can be located in close proximity to the sensing electrode 202 without being exposed to the reactive gas, so that the auxiliary electrode 218 and the sensing electrode 202 can be at the same temperature.With auxiliary electrode 218 and sensing electrode 202 at the same temperature (and with auxiliary electrode 218 not exposed to the target gas, while sensing electrode 202 is exposed to the target gas), the signal from auxiliary electrode 218 can be subtracted from that of sensing electrode 202 to compensate for long-term drift caused by temperature effects. Although the above technique can be used for some scenarios (e.g., for conventional uses of these sensors), it has been determined that for inhaled NO therapy, such techniques may not be sufficiently accurate for baseline drift. After extensive research, it was found that when these catalytic-type electrochemical sensors (e.g., sensors that are suitable for use with low concentrations of NO or for short periods of time) are used atypically in inhaled NO therapy, drift may be associated with the auxiliary electrode 218 drifting at a different detection rate than electrode 202; local temperature changes in the sensor electrode 202 may not be detected by auxiliary electrode 218; and / or auxiliary electrode 218 heating up at a different detection rate than electrode 202. It was also found that these temperature changes can be caused and / or exacerbated by the target gas (NO) having an exothermic (or endothermic) reaction at one or more of the electrodes (e.g., detection of electrode 202, versus electrode 206, etc.). In some cases, although these temperature changes may not be substantial when these sensors are used conventionally, they can be substantial for the atypical use of these sensors for inhaled NO therapy. For example, the concentration of NO used may be substantially higher than the concentration to which these types of sensors are conventionally exposed, and / or the duration of exposure of these sensors when used for therapeutic NO delivery may be substantially longer than the duration of exposure when these sensors are conventionally used for measuring toxic gas emissions. Taking into account the above changes, local temperature detection at electrode 202 may not be possible, or may be possible at a different rate, at the electrode P LO L Ln / ί7Π7 / E / YI auxiliary 218. With this local temperature change in the detection of electrode 202 not also occurring in auxiliary electrode 218, the drift of the base current cell cannot be corrected, as described above, simply by subtracting the signal of auxiliary electrode 218 from the detection of electrode 202. Further research also found that if the reactive gas is supplied (e.g., at the same concentration) for a long and sufficient duration of time (e.g., 24 hours), then the temperature at auxiliary electrode 218 can become the same as the temperature at the detection of electrode 202, e.g., the electrochemical sensor 200 can eventually achieve the equilibrium state, or similar. Temperature compensation In exemplary configurations, instead of and / or in combination with the calibration processes described above, to address at least some of the surprising phenomena described above, the local temperature at the electrode sensor (e.g., at specific times due to a set concentration of perceived NO) can be estimated (e.g., mathematically, using heat transfer analysis, etc.). Furthermore, the known signal (e.g., empirically determined) normally generated by the auxiliary electrode 218 at that estimated temperature can then be subtracted from the signal generated by the sensor electrode. Using this baseline technique, local drift at the sensing electrode can be compensated for at specific times.After steady state has been achieved, the baseline drift with respect to temperature can be compensated, as described above, by simply subtracting the auxiliary electrode 218 signal from the detection electrode 202. As an example, to determine the local temperature at the sensing electrode and / or the heat distribution (or temperature variation) in an electrochemical sensor 200 over time, the heat equation can be used. This heat distribution with respect to time can then be compensated for, for example, by subtracting the signal that would be expected from the auxiliary electrode 218 if they were at the same sensing temperature as electrode 202. As another example, the local temperature at electrode 202 at various times can be determined and / or compensated for using other methods. For example, a negligible internal resistance model can be used. In another example, empirical knowledge can be applied. In exemplary configurations, to address at least some of the phenomena described above, the electrochemical sensor 200 can be cooled. This cooling can be substantial enough so that, if an exothermic reaction occurs, the heat The generated P LO L Ln / ί7Π7 / Β / ΥΙ can effectively be dominated by the cooling temperature. Alternatively, this cooling may need to be substantial enough so that the steady-state temperature of the electrochemical sensor 200 can effectively be dominated by the cooling temperature. In exemplary embodiments, to address at least some of the phenomena described above, the steady-state temperature of the electrochemical sensor 200 and / or the local temperature of the sensing electrode (e.g., when equilibrium is reached) can be determined (e.g., mathematically, empirically, etc.). Then, the electrochemical sensor 200 can be preheated to or near that temperature, for example, to reduce the time required for the electrochemical sensor 200 to reach steady state. For instance, the electrochemical sensor can be preheated to a known temperature of the sensing electrode with a known concentration, and then, when the known concentration of the heat source is added, the electrochemical sensor can be brought back to steady state (e.g., not to the local temperature at the sensing electrode). In exemplary configurations, to address at least some of the phenomena described above, a secondary sensing electrode (either in the same sensor or in a different sensor used in the same NO delivery flow) can be intermittently activated to provide the appropriate signal output for the concentration being delivered. The difference between the output signal of the sensing electrode and the output signal of this secondary sensing electrode can be removed (for example, since it would be related to temperature drift) to compensate for zero drift. The frequency of the secondary sensing electrode used can be adjusted with respect to time. It will be understood that the sensor uses (for example, a primary electrochemical sensor that has a primary sensing electrode, a secondary electrochemical sensor that provides a secondary sensing electrode, etc.).) can be one of three terminals (e.g., non-auxiliary electrode). Dual sensors NO In exemplary configurations, the therapeutic gas delivery system may include two or more catalytic electrochemical sensors (e.g., two or more NO sensors) where, when one sensor is undergoing calibration (e.g., baseline calibration, etc.), the other sensor is exposed to the gas sample from the breathing circuit. Using this technique, when one sensor is offline (e.g., undergoing calibration, baseline calibration, etc.), the other sensor can remain online. Therefore, the user experiences no offline period during treatment. CLOLLn / LZnZ / E / Yli calibrations can be provided without interruption, for example, in the user interface, confirming that the therapeutic gas concentration the patient is receiving is the desired set dose. In exemplary modes, the sensors can be monitored intermittently (for example, one sensor can be exposed to the gas sample while the other sensor is exposed to zero-concentration gas) so that neither sensor becomes saturated. In exemplary modes, the second sensor can be used for drift determination in the same program as zeroing. In contrast to using two sensors to continuously monitor a sample gas, intermittent monitoring reduces the rate at which the sensors age and increases the time before sensor failure. Continuous exposure of a sensor to a low-humidity gas can cause the electrolyte sensor to dry out. Using a primary sensor and a backup sensor results in the sensors being under different conditions for different periods of time.Furthermore, while continuous exposure of both sensors can result in a comparable increase in drift for both sensors, which can lead to inaccurate cross-checking and near-simultaneous failure of both sensors, intermittent exposure of the backup sensor to the sampling gas in the inspiration line during calibrations increases sensor lifetime and allows for cross-checking of the primary sensor by a backup sensor with reduced drift. Intermittent use of the backup sensor also prevents sensor saturation with the target gas. Cross-checking allows two sensors to provide two separate calibration values ​​that can be compared to determine if the relative amount of drift exceeds a threshold value.If both sensors have similar but excessive tendencies due to equivalent exposure and aging, cross-checking would give a lower drift than the actual one. The gas sample (concentration reduction) In exemplary modalities, before exposing the catalytic-type electrochemical sensor (e.g., NO sensor) to the gas sample from a breathing circuit that may contain substantially high concentrations (e.g., >5 ppm) of the target gas (e.g., NO), the sample gas can be stream-mixed downstream (also known as metric ratio) so that the concentration of the target gas (e.g., NO) is reduced to a known amount. The sensor output can then factor in the known amount of the target gas that has been diluted to provide the user with confirmation that the therapeutic gas (e.g., NO) is being delivered at the desired concentration (e.g., desired set dose). Reducing the concentration of the target gas (e.g., NO) to which the sensor (e.g., NO sensor) is exposed can reduce and / or eliminate P LO L Ln / I 7Π7 / E / YΥ1ι the drift while allowing the monitoring of the established dose that is delivered to the patient. As an example, the diluent gas flow (e.g., from a non-reactive gas source, nitrogen gas flow, etc.) can be a mixed stream proportional to the sample gas flow from the breathing circuit to reduce the NO concentration in the sample gas. The sample gas flow rate can be known, for example, because the sample pump can draw the sample gas at a known flow rate; the gas flow rate can be controlled, for example, by a valve(s); and / or sample gas flow sensors can measure the sample gas flow rate. In exemplary configurations, the therapeutic gas delivery system can, for example, use machine-executable instructions to perform a calculation to reduce the concentration of the sample gas by mixing the sample gas with a diluent gas at a known concentration, such as nitrogen (e.g., from a nitrogen gas tank); the sample gas flow rate from the patient circuit using a sample gas flow sensor and / or the known flow rate from a sample pump; and the diluent gas flow rate reported by a gas flow sensor, the known flow rate of a diluent gas from a diluent gas pump, and / or the known flow rate of a diluent gas from a flow controller, such that the final NO concentration at the NO sensor is a fractional concentration delivered to the patient. Reducing the average concentration will minimize long-term drift. (E.g., valve(s), etc.). Intermittent monitoring In one modality example, to reduce drift in a catalytic electrochemical gas sensor (e.g., a NO sensor), the concentration of the therapeutic gas (e.g., a set dose of NO) delivered to the patient can be monitored intermittently, where the gas sensor is exposed to the target gas for a limited period of time rather than continuously. In various modalities, the exposure time may be slightly longer than the sensor's response time. By intermittently monitoring (e.g., instead of continuously) the target gas concentration, the amount of time the sensor is exposed to the target gas can be reduced, and during periods of non-exposure to the target gas, the sensor can be exposed to ambient air (e.g., conditioned room air). This P LO L Ln / ί7Π7 / Β / ΥΙ can be achieved using catalytic-type electrochemical gas sensors (e.g., NO sensors) that have a substantially fast response time (e.g., a few seconds, less than five seconds, etc.). As an example, instead of using a catalytic electrochemical sensor (e.g., a NO sensor) with a response time of approximately 15 seconds, catalytic sensors with a response time of around 5 seconds can be used. In this setup, the sensor can be exposed to the target gas (e.g., a high concentration of NO) for 5 seconds and then to ambient air (e.g., conditioned ambient air) for 10 seconds and / or for at least some of the remaining 10 seconds. During the period of non-exposure to the target gas, the output displayed to users via the user interface can be the value measured during the exposure period. This technique reduces or eliminates sensor drift while still effectively providing users with the same necessary information (e.g., confirmation that the desired dose setting is being delivered). Skilled practitioners will readily recognize numerous adaptations and modifications that can be made to the therapeutic gas delivery systems and method of delivering a pharmaceutical gas of the present invention, resulting in an improved method and system for introducing a known desired quantity of a pharmaceutical gas into a patient, all of which will fall within the scope and spirit of the present invention as defined in the following claims. Accordingly, the invention is limited only by the following claims and their equivalents. References throughout this specification to an embodiment, certain embodiments, one or more embodiments, an exemplary embodiment, examples of embodiments, and / or an embodiment mean that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, occurrences of phrases such as "in one or more embodiments," "in certain embodiments," "in an embodiment," "exemplary embodiment," "examples of embodiments," and / or "in an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment of the invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. It is understood that any of the steps described may be rearranged, separated, and / or combined without deviating from the scope of the invention. For ease of understanding, the steps are sometimes presented sequentially. This is merely for convenience and is in no way intended as a limitation. Furthermore, it is understood that any of the elements and / or embodiments of the described invention may be rearranged, separated, and / or combined without deviating from the scope of the invention. P LO L Ln / L7A7 / B / YL of the scope of the invention. For ease of use, various elements are sometimes described separately. This is merely for ease of use and is in no way intended as a limitation. It is understood that, at times, titles may be used. This is merely for ease of use and is in no way intended as a limitation. Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It will be evident to those skilled in the art that various modifications and variations may be made to the method and apparatus of the present invention without departing from the spirit and scope of the invention. Therefore, it is intended that the present invention includes modifications and variations that are within the scope of the appended claims and their equivalents.

Claims

1. A method for compensating for the drift of a nitric oxide sensor affiliated with a nitric oxide supply, the method characterized in that it comprises: storing, in a computer-readable non-transient memory affiliated with a nitric oxide supply system, a calibration line correlating the expected output values ​​of a nitric oxide sensor with nitric oxide concentrations and a calibration program providing times to perform a plurality of baseline calibrations, wherein the baseline calibrations are performed in response to a predetermined quantity change, wherein the baseline calibrations include exposing the nitric oxide sensor to a zero concentration of nitric oxide; and supplying, through the nitric oxide supply system, nitric oxide in an inspiratory flow of a circuit, according to a predetermined quantity;Monitor the output values ​​of the nitric oxide sensor, where the nitric oxide sensor is in fluid communication with the circuit, and where the output values ​​are indicative of the nitric oxide concentration in the inspiratory flow; determine the actual output value of the nitric oxide sensor during a baseline calibration of the nitric oxide sensor according to the calibration program; and augment the expected values ​​correlated with nitric oxide concentrations to include the difference between the actual output value and the expected output value.

2. The method according to claim 1, characterized in that the calibration program includes a set of values ​​representing the planned intervals between calibrations.

3. The method according to claim 1, characterized in that it further comprises the step of postponing baseline calibration when there is an alarm condition.

4. The method according to claim 1, further comprising the step of postponing baseline calibration when an alarm condition occurs within a predetermined interval before the scheduled baseline calibration.

5. The method according to claim 1, characterized in that it further comprises the step of postponing the baseline calibration when the presence of an interference gas is detected.

6. The method according to claim 1, characterized in that the baseline calibration includes exposing the nitric oxide sensor to ambient air.

7. The method according to claim 1, further comprising: identifying that a calibration of the nitric oxide sensor is to be carried out in accordance with the calibration program; exposing the nitric oxide sensor to a flow of a gas having a zero nitric oxide concentration; and measuring the nitric oxide concentration detected by the nitric oxide sensor during exposure to the gas having a zero nitric oxide concentration; wherein the calibration line is adjusted according to a detected drift between a baseline and the nitric oxide concentration measured when the nitric oxide sensor is exposed to the gas having a zero nitric oxide concentration.

8. The method according to claim 7, characterized in that the nitric oxide sensor is exposed to the gas having a zero nitric oxide concentration for a predetermined interval before the calibration line is set.

9. The method according to claim 7, characterized in that the gas having a zero concentration of nitric oxide is ambient gas.

10. The method according to claim 7, characterized in that it further comprises the step of postponing calibration when there is an alarm condition.

11. The method according to claim 7, characterized in that it further comprises the step of postponing calibration when an alarm condition occurs within a predetermined interval before the scheduled calibration.

12. The method according to claim 7, characterized in that it further comprises the step of postponing calibration when the presence of an interference gas is detected.

13. The method according to claim 1, characterized in that it further comprises: storing a calibration program and a calibration line in a computer-readable, non-transient memory of a controller system; wherein the calibration line has a baseline associated with a zero nitric oxide concentration; receiving a predetermined quantity of nitric oxide through the controller system; adjusting the nitric oxide concentration measurements in the circuit according to the calibration line and displaying a representation of the adjusted measurements on a screen; and identifying that a calibration is to be carried out according to the calibration program.Perform calibration, including: exposing the nitric oxide sensor to a gas having a zero nitric oxide concentration for a predetermined interval; measuring the nitric oxide concentration detected by the nitric oxide sensor while it is exposed to the gas having a zero nitric oxide concentration; and resuming continuous collection of nitric oxide concentration measurements in the circuit.

14. The method according to claim 13, characterized in that the baseline is associated with the nitric oxide concentration detected during the previous calibration.

15. The method according to claim 13, characterized in that the gas having a zero concentration of nitric oxide is ambient gas.

16. The method according to claim 13, characterized in that it further comprises the step of postponing calibration when there is an alarm condition.

17. The method according to claim 13, characterized in that it further comprises the step of postponing calibration when an alarm condition occurs within a predetermined interval before the scheduled calibration.

18. The method according to claim 13, characterized in that it further comprises the step of postponing calibration when the presence of an interference gas is detected.

19. The method according to claim 13, characterized in that the calibration program includes a set of values ​​representing the planned intervals between calibrations.