Abstract: The present application is directed toward a dynamic graphic communication system for use with various graphical user interfaces provided on the displays of anesthesia machines and other medical systems. Instead of using traditionally static icon, dynamic graphics are used to provide additional, intuitive information, including real-time information regarding the functioning of various components of an anesthesia machine, such as ventilator system, vaporizers and patient parameter monitors.

Abstract: A system for preventing the delivery of hypoxic gases during respiratory support of a patient includes a breathing circuit. An input device is operable by a clinician to input at least one ventilator parameter value. A fresh gas manifold is pneumatically connected to the breathing circuit and the fresh gas manifold is configured to provide at least oxygen and balanced gas to the breathing circuit. A digital signal processor is communicatively connected to the input device and the fresh gas manifold. The digital signal processor receives the input at least one ventilation parameter value, calculate a predicted oxygen concentration, and compares the predicted oxygen concentration to a predetermined minimal oxygen required threshold of the patient. A method of preventing the delivery of hypoxic gases to a patient includes providing ventilatory support to the patient through a breathing circuit. A digital signal processor receives a ventilation parameter value from an input device.

Abstract: The present invention discloses a method to compensate for a non-zero mixed venous partial pressure of inert blood soluble gas when determining physical parameter(s) of a patient in successive inert gas rebreathing tests. The method comprises the steps of: obtaining the partial pressure of said inert blood soluble gas inhaled and/or exhaled by said patient in a period prior to said successive rebreathing test; obtaining the partial pressure of said inert blood soluble gas inhaled and/or exhaled by said patient in said successive rebreathing test; determining said physical parameters) using said partial pressure of said inert blood soluble gas inhaled and/or exhaled by said patient and obtained in said period prior to said successive rebreathing test and said partial pressure of said inert blood soluble gas inhaled and/or exhaled by said patient and obtained in said successive rebreathing test. Furthermore the present invention relates to a corresponding system and computer-readable medium.

Abstract: The present disclosure refers to a system to control mechanical lung ventilation with volume band, more particularly a system to manage respiratory cycles in patients. Preferably, said respiratory cycles are controlled under pressure, so that the volumes as inspired by the patient are maintained within a volume range, comprising a lower volume limit and an upper volume limit, which are previously determined.

Abstract: The present disclosure relates to methods and apparatus for detecting when respiratory cartridges of a respirator have reached their end-of-service-life. In some instances, two or more respiratory cartridges are removably connectable to a respirator housing, where each of the two or more respiratory cartridges receives ambient air and deliver cleaned air to the respirator housing. One of the respiratory cartridges may be configured to have a lower adsorption capacity than the remaining respirator cartridges. A gas sensor may be situated downstream of the reduced capacity respirator cartridge, and may detect an increased concentration of the targeted gas in the cleaned air delivered by the reduced capacity respiratory cartridge. When detected, an end-of-service-life indication may be provided to the user.

Abstract: Apparatus for respiratory anaesthesia of a patient by administration of a gas containing gaseous xenon, with a main gas circuit which is open or closed and has an inhalation branch and an exhalation branch, means for supply of gaseous xenon to the inhalation branch of the main circuit, and means for determining the xenon concentration. The means for determining the xenon concentration comprise at least one hot-wire sensor having at least one electrically conducting wire in direct contact with the gaseous flow containing the xenon, calculating means that cooperate with the hot-wire sensor(s) in order to determine the xenon concentration (Xe %) in the flow, means for generating an electrical current in order to generate a current in at least one hot wire, and means for voltage measurement that can measure at least one voltage value at the terminal of at least one hot wire or at least one resistance arranged in series with at least one hot wire.

Abstract: A bi-level pressure support system and method of treating disordered breathing that optimizes the pressure delivered to the patient during inspiration and expiration to treat the disordered breathing while minimizing the delivered pressure for patient comfort. The pressure generating system generates a flow of breathing gas at an inspiratory positive airway pressure (IPAP) during inspiration and at an expiratory positive airway pressure (EPAP) during expirations. A controller monitor at least one of the following conditions: (1) snoring, (2) apneas, (3) hypopneas, or (4) a big leak in the pressure support system and adjusts the IPAP and the EPAP based on the occurrence of any one of these conditions.

Abstract: A patient ventilator for assisting a clinician in determining a suitable PEEP for the patient. The amount of the lung volume recruited/de-recruited at various levels of PEEP may be determined for use in selecting a desired PEEP. To this end, the functional residual capacity of the lungs is determined for a first PEEP level. The PEEP is then altered to a second level and a spirometry dynostatic curve of lung volume and pressure data is obtained. The lung volume on the dynostatic curve at a lung pressure corresponding to the first PEEP value is obtained. The difference between the functional residual capacity of the lungs at the first PEEP level and that determined from the dynostatic curve represents the lung volume recruited/de-recruited when changing between said first and second PEEPs.

Abstract: A method and apparatus for automatically controlling partial pressure of oxygen in the breathing loop of a rebreather diving system. A diver may adjustably select a control parameter to maintain partial pressure of oxygen at a setpoint that varies with ambient pressure and is within a range between a maximum safe partial pressure of oxygen at depth and a minimum safe partial pressure of oxygen for the purpose of biasing the performance of the rebreather either towards minimizing gas venting from the rebreather breathing loop or minimizing decompression time. A method and apparatus for managing and monitoring the use of dive resources in comparison with a target dive time specified by the diver, calculating and indicating remaining dive time based on dive resource values and calculating and indicating dive resource values required to meet preselected dive resource end values and dive requirements.

Abstract: A gas measurement apparatus can comprise a sensor and a processor, in an example. The sensor can measure a pressure condition of a gas tank, in an example. The processor can select at least one light source, the light source can be positioned or be of a distinct color to indicate a corresponding level of gas remaining in the tank when illuminated. The level of gas can be based on the measured pressure. Banks of high intensity LEDs can allow visually discernable colors at a significant distance underwater. A visual beacon mode can be included. An alphanumeric pressure readout mode can be included. A depth sensor can be included.

Abstract: Embodiments of the present invention described and shown in the specification and drawings include a system and method for monitoring the ventilation support provided by a ventilator and automatically supplying a breathing gas to a patient via a breathing circuit that is in fluid communication with the lungs of the patient.

Abstract: A ventilator includes first and second pathways, a conduit and a controller. The first pathway (120) is configured to supply a first gas and the second pathway (140) is configured to supply a second gas, where the second gas is mixed with the first gas to produce mixed gas having a predetermined percentage of the second gas. The conduit (166) is configured to provide the mixed gas from the first and second pathways to an access port during an inspiratory phase, and to provide discharged gas from the access port to the first pathway during an expiratory phase. The controller (180) is configured to delay supply of the second gas from the second pathway for a delay time in order to maintain the predetermined percentage of the second gas in the mixed gas provided to the access port during a subsequent inspiratory phase.

Abstract: A gas measurement apparatus can comprise a sensor and a processor, in an example. The sensor can measure a pressure condition of a gas tank, in an example. The processor can select at least one light source, the light source can be positioned or of a distinct color to indicate a corresponding level of gas remaining in the tank when illuminated. The level of gas can be based on the measured pressure.

Abstract: Disclosed are devices, systems, and methods, including an oxygen delivery device that includes an oxygen delivery module to produce at least concentrated oxygen, a gas moving device to deliver air to the oxygen delivery module, at least one motor to controllably drive the gas moving device, an energy source to power at least the at least one motor, a pressure sensor to determine a pressure level, and a purity sensor to determine oxygen purity value. The device also includes a controller to control, based on the oxygen purity value and the pressure level, at least the gas moving device's operations and the oxygen delivery module's operations to cause the pressure resulting from gas moving device to be substantially at a pre-determined pressure value and to cause the purity level of the oxygen produced by the oxygen delivery module to be substantially at a pre-determined purity value.

Abstract: A system for regulating the airflow to a closed environment using feedback control for the position of a control valve and blower speed. The system provides a control apparatus that regulates airflow to a closed environment, such as the mask of a breathing apparatus, to ensure sufficient breathing air for a wearer of such mask. In order to provide fast response to a change in condition in the breathable environment, the airflow regulator includes a valve control and a blower control.

Abstract: The present invention discloses a method for improving control and detection precision of tidal volume by introducing R value, comprising the steps of: a plateau pressure Pplate is used to calculate a system compliance C with C=?V/(Pplate?PEEP); VT, the tidal volume obtained currently at patient terminal, is calculated with VT=?V×(C?Ctube)/C, wherein ?V is the variation of tidal volume, PEEP is the positive end expiratory pressure and Ctube is the compliance C of the line. Depending on the calculated VT, the tidal volume which is actually obtained by the patients during this period, the processing unit calculates the tidal volume VT?, which the airway is intended to reach during the next expiration period, by VT?=VT+?VT×K wherein K is a scaling factor for control and adjustment, VT is the tidal volume obtained by the patient during the current period, VTset is the presetted tidal volume, ?VT=VTset?VT.

Abstract: A method for maintaining a volume of a breathing gas in a desired level when ventilating a subject is disclosed herein. The method includes supplying the volume of the breathing gas for an inspiration and receiving the volume of the breathing gas for an expiration and withdrawing a gas sample from the volume of the breathing gas for an analysis. The method also includes providing a signal indicative of a volume of the gas sample withdrawn and determining the volume of the gas sample based on providing the signal. The method further includes controlling a volume of a compensation gas configured to be added into the breathing gas based on determining the volume of the gas sample for maintaining the breathing gas volume in the desired level. A corresponding arrangement for maintaining a volume of a breathing gas in a desired level is also provided.

Abstract: Inhalation anaesthesia delivery system and a leak detecting method, whereby the system comprises a fresh gas feeding arrangement connected to a breathing circuit, a monitor device, The monitor device is configured to monitor gas concentrations in the breathing circuit by using a sampling line. The monitor device is configured to measure at least two gas components' concentrations and identify changes, which are simultaneous towards the known ambient air concentration values of the two gas components' concentrations measured.

Abstract: A patient interface in accordance with one embodiment of the present invention is configured to be at least partially carried by a patient and to receive gas exhaled by the patient. The patient interface includes first and second cannula tubes each having a first end and a second end, the first ends are configured to be inserted into the nostrils of a patient, the first and second cannula tubes are configured to direct exhaled gas from the patient from the first ends to said second ends. The patient interface also includes first and second sensors positioned near the second ends, and the first and second sensors are configured to provide first and second signals based upon the gas, wherein the first and second signals are indicative of a physiological parameter of the patient. The patient interface also includes a communications link configured to provide the signal to a physiological monitor.

Abstract: A sound dampening apparatus to be disposed in pneumatic connection with a respiratory support system. The respiratory support system may comprise a source of medical gas, a plurality of pneumatic connections and a patient interface. The sound dampening apparatus comprises an inlet, an outlet, and an outer case which forms a sound dampening chamber. As the medical gas flows through the sound dampening apparatus, the noise energy associated with the flow of medical gas is reduced.

Abstract: A system and method of monitoring a patient, that in one embodiment, comprises determining a flow of gas generated by respiration of the patient, identifying a respiratory event entry and a respiratory event exit based on the flow of gas generated by respiration of the patient, and identifying a respiratory event when the identification of the respiratory event entry is followed by the identification of respiratory event exit.

Abstract: A method and apparatus for delivering breathable gas to a user includes a humidifying unit that is controllable to humidify the gas in accordance with a variable humidity profile such that the gas is delivered to the user at variable humidity levels, e.g., during a treatment session.

Abstract: An artificial ventilation apparatus includes: a connecting portion which is connected to a respiratory system of a patient; an inspiratory circuit which is a flow path for flowing a gas from a ventilator to the connecting portion; an expiratory circuit which is a flow path for guiding a gas exhausted from the connecting portion to an exhaust portion of the ventilator; an expiratory valve which blocks a flow of a gas from the exhaust portion toward the connecting portion; a carbon dioxide concentration sensor which is disposed in a circuit that is provided at a downstream side of the expiratory valve and which detects a carbon dioxide concentration; and an alarm outputting unit which outputs an alarm based on an output of the carbon dioxide concentration sensor.

Abstract: The present invention is a breathing improvement monitor that continuously measures involuntary breathing. The monitor is a sensor apparatus that is attached to a patient's mask which is connected to the monitoring apparatus. The sensor may be reusable and attachable and detachable to a mask or it may be an integral part of a breathing mask. The sensor technology may be any type sufficient in the art, including but not limited to solid state sensors, transducers, electromagnetic microturbines and the like. Since the mask does not have to be removed and the sensor provides constant signal to the monitoring apparatus, a real time status of a patient's involuntary breathing capability may be determined for a doctor's consideration.

Abstract: The invention concerns a combination control for use in nasal cannula therapy, and includes a high flow, nasal cannula respiratory assistance ducted system.

Abstract: Improved methods and devices are described for sensing the respiration pattern of a patient and controlling ventilator functions, particularly for use in an open ventilation system. A ventilation and breath sensing apparatus may include a ventilation gas delivery circuit and a ventilation tube coupled to the ventilation gas delivery circuit. A plurality of pressure sensing elements may be separated by a distance and may produce independent signals. The signals may be used to detect pressure differentials between the plurality of pressure sensing elements. Sensing ports may be located in an airway, and connected to transducers that are valved to optimize sensitivity and overpressure protection. Airway pressure and flow can both be obtained and used to optimize ventilator synchronization and therapy.

Abstract: A veterinary anesthesia monitor system useful in establishing, maintaining, and reporting upon the anesthesia gas mixture delivered to or exhaled by a patient.

Abstract: The system and method includes a treatment device such as an anesthetic machine or IV, a monitor and a display configured to display real-time PK/PD data associated with an anesthetic agent administered to the patient. The system and method further includes a safety control means configured to control the display such that one of a basic display state, an interactive effects display state, and a display inhibited state is selected and displayed according to the anesthetic agents and levels of the same being administered to the patient.

Abstract: The present invention is a system and method for integrating anesthesia agent monitoring in a respiratory carestation, wherein the respiratory carestation is configured to be compatible with a variety of monitoring modules. Any one of the monitoring modules is inserted into a module bay, and a sampling line couples the monitoring module to the patient circuit, such that the patient monitoring parameters are displayed on a user interface of the respiratory carestation.

Abstract: A method of detecting disconnect of a patient circuit of a ventilation system, wherein a circuit disconnect is detected with a first sensitivity and a second sensitivity. The circuit disconnect detected with the first sensitivity is performed by detecting a volume loss for a minimum period of time, detecting a peak pressure loss for at least two consecutive breathing cycles or a minimum period of time, and detecting a pressure loss continuing for a predetermined period of time. The circuit disconnect detected with the second sensitivity is performed by detecting a volume loss for a single breathing cycle, detecting a pressure loss for a single breathing cycle, and detecting an increase of compliance. The first sensitivity is lower than the second sensitivity. Preferably, an alarm is activated when the circuit disconnect is detected with the first sensitivity, and subsystems of the ventilation system is informed of the circuit disconnect that has been detected with the second sensitivity.

Abstract: A CPAP device includes an air stream generator for generating positive pressure, a face mask connected to the air stream generator through a flow supply catheter, a pressure sensor measuring pressure in the face mask, a control circuit controlling the air stream generator, and a pressure detection pipe having a first side and a second side. The pressure sensor is connected to the second side of the pressure detection pipe to measure pressure of the detection hole formed at the first side of the pressure detection pipe and outputs the measured pressure value to the control circuit. The control circuit distinguishes average positive pressure from pressure caused by spontaneous breathing of patient according to values of the pressure in the face mask, which are input from the pressure sensor, and controls a speed of the air stream generator such that preset positive pressure is supplied to the patient.

Abstract: A method of treating a patient with a pulmonary disease, where the method includes delivering a dose of aerosolized medicament intermittently to a ventilator circuit coupled to the respiratory system of the patient. Also, a method of treating a patient with a pulmonary disease, where the method includes taking the patient off a ventilator, and administering to the patient, a nebulized aerosol comprising from about 100 ?g to about 500 mg of a medicament. Additionally, an aerosolized medicament for the treatment of a pulmonary disease, where the medicament includes amikacin mixed with an aqueous solution having an adjusted pH from about 5.5 to about 6.3. The pH is adjusted by adding hydrochloric acid and sodium hydroxide to the aqueous solution.

Abstract: The method and system are for sealing/unsealing (regulating) airway leaks occurring between the ventilator circuit and respiratory airways during lung ventilatory support in response to myoelectrical activity of diaphragm. Myolectrical activity of a patient's respiratory-related muscle is sensed to detect respiratory effort, and to produce a myoelectrical signal representative of the sensed muscle myoelectrical activity. Respiratory flow and pressure can also be measured to produce respective respiratory pressure and respiratory flow signals. A logic trigger sealing/unsealing of airway leaks in relation to the myoelectrical signal, respiratory flow signal and/or respiratory pressure signal to assist respiration of the patient. The amplitude of the myoelectrical signal is compared to a given threshold, and airway leaks are sealed when the amplitude of the myoelectrical signal is higher than this threshold.

Abstract: This disclosure describes systems and methods for ventilating a patient with a system that includes an accumulator for storing a gas mixture. The disclosure describes systems and methods for ventilating a patient with a system that includes an accumulator located away from the flow path that reduces or eliminates pockets or burps of an undesirable gas mixture from entering the gas flow path and reaching the patient after a gas mixture change. The disclosure also describes a novel approach for reducing or eliminating these air pockets of undesirable gas by utilizing a dip-tube.

Abstract: This disclosure describes systems and methods for ventilating a patient with a system that includes an accumulator for storing a gas mixture. This disclosure describes systems and methods for ventilating a patient with a system that includes an accumulator located away from the flow path that reduces/eliminates pockets of an undesirable gas mixture from entering the gas flow path and reaching the patient after a gas mixture change by utilizing a purge valve.

Abstract: This disclosure describes systems and methods for ventilating a patient with a system that includes an accumulator for storing a gas mixture. The disclosure describes a novel approach for determining the concentrations of gas found in the accumulator by utilizing a sampling chamber. The disclosure further describes a novel approach for a fast delivery of a change in gas mixture to a patient by utilizing a variable-sized accumulator. This disclosure also describes systems and methods for ventilating a patient with a system that includes an accumulator located away from the flow path that reduces/eliminates pockets of an undesirable gas mixture from entering the gas flow path and reaching the patient after a gas mixture change by utilizing at least one of a dip-tube, a purge valve, and a variable size accumulator.

Abstract: This disclosure describes systems and methods for ventilating a patient with a system that includes an accumulator for storing a gas mixture. The disclosure further describes a novel approach for a fast delivery of a change in gas mixture to a patient by utilizing a variable-sized accumulator.

Abstract: An exhalation valve assembly that controls the pressure of exhaled gas in a ventilation system is described. The exhalation valve assembly includes an actuator module that may be fixed to the ventilation system and a valve module, removable for cleaning or disposal, through which the exhaled gas flows and that controls the pressure and release of the exhaled gas to the environment. Other components may also be incorporated into the assembly including a filter module, a flow meter and a condensate trap.

Abstract: An exhalation valve assembly that controls the pressure of exhaled gas in a ventilation system is described. The exhalation valve assembly includes an actuator module that may be fixed to the ventilation system and a valve module, removable for cleaning or disposal, through which the exhaled gas flows and that controls the pressure and release of the exhaled gas to the environment. Other components may also be incorporated into the assembly including a filter module, a flow meter and a condensate trap.

Abstract: The Invention is directed to an oxygen sensor arrangement (8) and a method for operating such an arrangement for sensing the oxygen in a breathing loop (29) of a breathing apparatus. The sensor arrangement comprises: at least one primary oxygen sensor (30) arranged to operatively measure the oxygen in the breathing loop (29), at least a secondary oxygen sensor (31) arranged to operatively measure the oxygen in the breathing loop (29), and a control arrangement (40) for obtaining measures from said oxygen sensors. A test channel arrangement (15, 48) is adapted to operatively provide a first gas having a first fraction of oxygen from a first gas supply (16) to said primary oxygen sensor (30) at a position (267) adjacent to said primary oxygen sensor (30). At least a first test valve arrangement (41, 42) is arranged to operatively open and close the flow of said first gas through said test channel arrangement (15, 48).

Abstract: A system and a method for circuit compliance compensated pressure control in a patient respiratory ventilation system, having a pressure regulated feedback servo control loop, a pressure-regulated volume controller, and a patient volume observer. The patient volume observer is operative to estimate a patient volume, that is, the volume actually delivered to the patient by accounting for volume deviation or loss caused by patient circuit leakage and valve dynamics. Based on the difference between the estimated patient volume and a set tidal volume, the pressure-regulated volume controller is operative to generate and update a circuit compliance pressure compensation factor. The pressure regulated feedback servo control loop is operative to modulate the peak airway pressure based on the circuit compliance pressure compensation factor, so as to achieve the set tidal volume while maintaining a constant inspiratory time and a constant I:E ratio.

Abstract: Disclosed are methods, systems, apparatus, and products, including a method for operating a respiratory care device that includes collecting at a respiratory care device data representative of operation of the respiratory care device, and communicating to a computing-based device external to the respiratory care device at least some of the collected data to control the operability of the respiratory care device. In some embodiments, the method may further include communicating to the respiratory care device data to controllably change one or more operation parameters of the respiratory care device to cause a change in the operation of the respiratory care device, changing the operation parameters of the respiratory care device according to the communicated data, and communicating to the external computing-based device resultant data representative of operation of the respiratory care device resulting from the controllable change to the one or more operation parameters.

Abstract: The present invention generally provides methods and systems for managing a medical gas system by using wireless sensors located at the point of use. In one embodiment, a wireless sensor is fixed to a gas outlet, and is configured to measure gas flow, and to detect whether the gas outlet is connected to a medical device. The gas flow and connection data is included in a wireless signal that is transmitted to a remote server. The data received by the server may be analyzed to determine if any local or system leaks are occurring. In addition, the data may be used to monitor patient therapies, to calculate costs, and to determine replenishment points.

Abstract: A trans-fill method and system comprising obtaining therapeutic gas from a therapeutic gas source, compressing the therapeutic gas from the therapeutic gas source in at least two stages to create an intermediate therapeutic gas stream and a high pressure therapeutic gas stream, supplying therapeutic gas to a patient from the intermediate therapeutic gas stream, and filling a cylinder with the therapeutic gas from the high pressure therapeutic gas stream substantially simultaneously with supplying therapeutic gas to the patient.

Abstract: A medicine ejection device is provided allowing a medicine with a desired droplet diameter to be inhaled at a constant rate. The medicine ejection device has a decision part at which the ejection operating conditions of a medicine ejection part for ejecting the medicine are decided in accordance with at least one of an open-air environment or a state of the medicine during use of the device. The device ejects the medicine according to the ejection operating conditions decided by the decision part.

Abstract: A circuit compliance compensated volume control system in a patient respiratory ventilation system and method, including: a circuit compliance estimator, to provide a relationship between a circuit volume and a differential pressure between a circuit pressure and a positive end-expiratory pressure (PEEP) of the respiratory circuit, a circuit volume estimator, operative to provide an estimated circuit volume based on the relationship between the circuit volume and the differential pressure, a patient volume observer, operative to provide an estimated patient volume by subtracting the estimated circuit volume from a measured machine delivered net volume, and a volume delivery controller, operative to update the machine delivered net volume based on the estimated patient volume and a set tidal volume.

Abstract: An oxygen concentrator may rely on a pressure swing adsorption process to produce an oxygen enriched gas stream from canisters filled with granules capable of separation of oxygen from an air stream. The adsorption process uses a cyclical pressurization and venting of the canisters to generate an oxygen enriched gas stream. The oxygen concentrator system may operate in multiple modes, automatically determined or selected by the user, to take into account the different activity levels of the user.

Abstract: A method and an apparatus for controlling a ventilator to automatically adjust ventilation assistance to an active or passive subject. The method includes determining volume and flow rate of gas to the patient during inspiration on an ongoing basis, and generating control signals in proportion to the volume and flow rate of gas to the patient wherein proportionality factors, and support levels for the elastic and resistive components of pressure are automatically adjusted by the ventilator. The ongoing pressure applied by the ventilator is a sum of elastic and resistive pressures that are automatically controlled by the system. When the patient breathes spontaneously, the support levels are automatically adjusted based on the patient's requirements. If the patient does not breathe spontaneously, the ventilator provides ventilation at an optimal level and rate. The method may be used in weaning or in a management phase of ventilation.

Abstract: A ventilator includes a sensor to monitor a characteristic associated with the delivery of gas to the patient, such as pressure. A sensor power supply (100, 130) is feeding a sensor in the form of a Wheatstone bridge. A first end (104) of the bridge is coupled to a first positive voltage source (112, 142) and a second end (116) is coupled to a second positive voltage source (118, 156, 180). A capacitor (120) is coupled to the second end of the bridge.

Abstract: The invention relates to a method for operating a rebreather, wherein oxygen is metered to the breathing gas as a function of a signal of at least one oxygen sensor (11). The oxygen sensor (11) is checked automatically by rinsing it with a gas having a known oxygen concentration. The safety of the system is improved in that the check is triggered automatically.