65 results about "Inspiratory phase" patented technology

The invention belongs to the technical field of intelligent rehabilitation equipment control, and relates to a multi-parameter feedback regulation and control method for postoperative lung function rehabilitation training, which comprises the following steps: acquiring an electrocardiosignal, a respiration signal and a limb movement signal of a patient; identifying a heart rate fluctuation form of the electrocardiosignal to generate an abnormal fluctuation time period, and analyzing a time difference between an inspiration phase and an expiration phase of the respiratory signal to generate a starting point of respiratory rhythm disorder; judging a cardiopulmonary risk level; the exercise intensity of rehabilitation training equipment is automatically adjusted based on the cardiopulmonary risk level, and meanwhile a regulation and control mode is dynamically selected according to the proportion change of the chest fluctuation amplitude and the abdomen fluctuation amplitude; when the heart rate recovery rate is lower than a preset reference and the respiratory rhythm stabilization time exceeds a critical value, gradually improving the exercise intensity; calculating a motion intensity correction coefficient and triggering a motion posture correction instruction; and generating a rating report containing the cardiopulmonary function fitness. According to the invention, the problem of lack of comprehensive quantitative evaluation of rehabilitation efficiency in the prior art is solved.

The invention relates to the technical field of emotional robots, and discloses an embracing emotional robot which comprises an inner shell, low-cost and high-simulation breathing simulation is achieved through cooperative control of an air pump and an air valve, and the embracing emotional robot is designed by combining simulation body temperature brought by a heating piece and synchronous action of a rotatable arm. The emotion robot can naturally rotate forwards when being embraced and is matched with simulated respiration and simulated body temperature, so that the immersion and emotion interaction experience of a user are remarkably improved; the operation cycle of the air pump strictly follows biological breathing characteristics, the inspiration stage accounts for 2 / 3 of the breathing cycle, the speed of the inspiration stage changes fast and slow, the expiration stage accounts for 1 / 3 of the expiration stage, smooth pressure relief is achieved through the air valve, and the highly-simulated breathing mode can effectively guide a user to breathe synchronously, so that parasympathetic nerves are activated, the anxiety level and heart rate fluctuation are reduced, and the user experience is improved. And the whole structure adopts a modular design, complex functions such as breathing simulation, embracing and body temperature simulation can be realized, the maintenance is convenient, and the device is particularly suitable for long-term accompanying scenes.

The invention provides a method and equipment for constructing lung function characteristics during sleep. The method is applied to lung function data processing. The method comprises the following steps: collecting a breathing velocity waveform of a target object; determining an inspiration stage and an expiration stage in each respiratory cycle based on the respiratory velocity waveform; the duration of each stage is determined based on the inspiration stage and the expiration stage, and the duration of the inspiration sub-stage and the duration of the expiration sub-stage are obtained; basic features, a stability measurement feature group and a comprehensive feature group are calculated based on the inspiration sub-stage duration and the expiration sub-stage duration; according to the method, the breathing speed waveform is acquired without burden, and the comprehensive lung function evaluation feature group suitable for the radar breathing waveform is constructed.

The invention relates to the technical field of respiratory metabolism detection, in particular to a respiratory metabolism detection method and a bidirectional gas collection and detection device. The respiratory metabolism detection method comprises the following steps: respectively collecting gas in an inspiration stage and an expiration stage participating in respiration through an inspiration collection channel and an expiration collection channel which are mutually independent in a bidirectional gas collection and detection device; the collected gas sample is detected through a sensor in the integrated gas analysis module; the data processing module is used for receiving detection data transmitted by the sensor, and the data is accurately calibrated according to a preset calibration standard and an intelligent data processing algorithm; component concentration calculation is performed on the calibrated data, and an accurate gas component concentration value is obtained through an algorithm according to response characteristics of different gas components on the sensor; and in combination with respiratory parameters such as respiratory frequency and respiratory depth, gas components in two processes of expiration and inspiration are collected and analyzed in the same equipment at the same time.

The invention relates to the technical field of micro-grid atomizers, and discloses a breath triggering micro-grid atomizer based on a thermocouple sensor, which comprises a second port and a third port of a three-way pipe, the breathing sensing module is provided with a differential sensing array on a flexible circuit board, and a sensing unit at least comprises a thermocouple sensor; the atomization module integrates an impedance measurement circuit and a driving circuit on a flexible circuit board, and a micro-grid transducer is multiplexed to sense the self state; the controller carries out weighted fusion on sensing unit signals in the differential sensing array and predicts the inspiration starting moment, a pre-triggering instruction is sent out at the expiration end stage to drive the energy converter to pre-charge atomized liquid medicine at low power, impedance characteristics are synchronously collected to obtain the micro-grid efficiency value, the inspiration phase carries out compensation and correction on driving power according to the real-time flow proportion and the efficiency value, and the micro-grid efficiency value is adjusted according to the real-time flow proportion and the efficiency value. And applying a reverse pulse to the expiratory phase to clean the micro-grid and recording the effect to predict the subsequent cleaning opportunity. Closed-loop control of respiratory phase prediction triggering, staged scheduling and efficiency self-calibration is achieved.

Neurostimulation therapy can be efficiently controlled based on information from an acceleration signal, such as can be obtained from an accelerometer. In an example, the accelerometer can be implanted in a cervical region or submandibular region of a patient. Circuitry can be configured to identify a first series of respiration phase transition events in the acceleration signal and, in response, provide the neurostimulation therapy synchronously with an inspiration phase of a patient's respirator cycle. In an example, m absence of identifying the first series of respiration phase transition events in the acceleration signal, the neurostimulation therapy can be provided asynchronously with the patient's respiratory cycle.

This application relates to a continuous positive airway pressure (CPAP) device and a method for controlling ventilation pressure. The minimum operating pressure is determined by acquiring a preset treatment pressure and a target pressure drop. The device monitors the patient's respiratory phase transitions in real time and employs different pressure regulation strategies for the inspiratory and expiratory phases. During the inspiratory phase, the ventilation pressure is smoothly adjusted from the preset treatment pressure to the minimum operating pressure and maintained to reduce inspiratory effort. During the expiratory phase, the ventilation pressure is gradually increased from the minimum operating pressure to ensure that the ventilation pressure returns to the preset treatment pressure at the end of the expiratory phase, maintaining airway support and avoiding the risks of airway closure and central apnea. This application improves patient comfort during CPAP therapy, enhances treatment compliance, and simultaneously ensures airway support while reducing the risks of airway closure and central apnea.

This invention discloses an intelligent mask sealing detection system and method based on active biomimetic fit adjustment, belonging to the field of intelligent protective equipment detection technology. The system includes the following steps: collecting breathing change information and fit contact feedback information between the mask and face throughout the entire mask-wearing process, and organizing this information according to the temporal relationship between the inhalation and exhalation phases to generate a breathing fit rhythm sequence reflecting the correspondence between breathing fluctuations and fit changes. This invention uses the breathing fit rhythm as its core to dynamically analyze the fit state, identifying short-term air leakage phenomena where the time deviation of the fit response during breathing rhythm switching is synchronized with the inhalation peak, thus avoiding misjudgments of sealing. Furthermore, based on the leakage distribution pattern, it pre-adjusts the fit adjustment and sampling sequence to ensure that the detection covers key change areas, improving the reliability of mask protection under complex breathing conditions.

This invention relates to the field of high-frequency ventilator technology and discloses a high-frequency ventilator operating method based on flow control. The high-frequency ventilator sequentially outputs multiple average airway flow rates of the same or different magnitudes and with the same or different durations according to a set periodic pattern. The airway flow rate output is stable during the expiratory and inspiratory phases, and the average airway flow rate can be output at the same or different magnitudes during different inspiratory and expiratory phases. The output gas flow rate of the high-frequency ventilator can be independently adjusted periodically between different ventilation flow rate levels within different durations. In high-frequency ventilation, the flow control-based high-frequency ventilation method can precisely control the gas flow rate and time. Flow control ventilation can better control changes in airway pressure. By setting appropriate flow rates and times, the delivery volume of the device can be accurately estimated to reduce airway pressure and risks, and lower the possibility of barotrauma.

The application relates to the technical field of intelligent vehicle-mounted technology, in particular to a breathing synchronization intelligent vehicle-mounted oxygen supply control method and system, which comprises the following steps: emitting electromagnetic waves to passengers through a millimeter wave radar and receiving reflected echo signals; performing signal processing on the reflected echo signals to obtain periodic signal waveforms; identifying the inspiration stage and the expiration stage of the passengers based on the periodic signal waveforms; outputting an opening instruction in response to the identification of the inspiration stage; outputting a closing instruction in response to the identification of the expiration stage; and based on the analysis of the periodic signal waveforms formed by the passengers in a plurality of historical breathing cycles, predicting the starting moment of the next inspiration stage and outputting the opening instruction at a preset time point before the predicted starting moment of the inspiration stage. The oxygen utilization rate is greatly improved, so that a smaller-power oxygen generator or a smaller-capacity oxygen storage tank can be used under the condition of the same effective oxygen uptake, thereby reducing the system volume, weight, cost and energy consumption.

The present invention belongs to the technical field of ventilators, and in particular relates to a method, device, and ventilator for controlling the transition adjustment of a PEEP valve during the inhalation and exhalation phases. The method comprises: when the ventilator switches from the inhalation phase to the exhalation phase, controlling the control amount of the PEEP valve to adjust from the inhalation phase control amount to the exhalation phase control amount according to a preset switching time and transition curve; when the ventilator switches from the exhalation phase to the inhalation phase, controlling the control amount of the PEEP valve to adjust from the exhalation phase control amount to the inhalation phase control amount according to a preset switching time and transition curve. Using the method of the present invention, the PEEP valve can be continuously controlled without step changes during the ventilator phase switching, thus overcoming the patient's discomfort caused by airflow tremors in the pipeline and improving the quality of the ventilator.

The invention discloses an external phrenic nerve electrical stimulator with synchronous breathing, belongs to the technical field of medical equipment, and aims to solve the problems of low diaphragm contraction efficiency and discomfort of a patient caused by non-synchronization of electrical stimulation and inspiration action of the patient in breathing machine treatment. The device detects inspiration flow velocity signals in real time through a flow velocity sensor connected to a patient end of a breathing machine pipeline, and the inspiration flow velocity signals are amplified and filtered by a signal conditioning circuit and then transmitted to a control unit; the control unit judges whether the inspiration flow rate reaches the standard or not based on a preset threshold value, and synchronously triggers the electrical stimulation module to output a pulse signal matched with the inspiration period of the breathing machine to the phrenic nerve. The core of the technical scheme comprises flow rate signal dynamic detection, threshold value judgment logic and self-adaptive adjustment of electrical stimulation pulse envelope duration, and it is ensured that electrical stimulation is accurately synchronized with an inspiration stage. The device is mainly used for assisting a respirator user in enhancing the phrenic nerve driving capacity and improving ventilation and blood flow ratio imbalance, and is suitable for rehabilitation treatment of patients with chronic respiratory failure or diaphragm dysfunction.

This invention discloses an intelligent, adaptive local oxygen supply system and its control method, belonging to the technical field of oxygen supply auxiliary equipment. The system includes an oxygen supply module, a target tracking module, an adaptive air delivery module, and a control module. The target tracking module acquires the spatial coordinate information of the user's face or nasal cavity area in real time; the control module generates a pointing command based on the spatial coordinate information, driving the adaptive air delivery module to perform displacement compensation, ensuring the oxygen jet direction is towards the target area. Furthermore, the system, through a respiratory rhythm monitoring module in conjunction with a throttle switch, closes the throttle switch during the exhalation phase and accumulates pressure in the buffer pressurization container; during the inhalation phase, it triggers the throttle switch in advance to release pressurized oxygen based on the airflow flight time difference calculated by the infrared ranging module, achieving synchronous coverage of the oxygen jet and the inhalation peak. This invention can automatically adjust the air delivery direction according to changes in the user's position and match the respiratory rhythm for intermittent pressurized oxygen supply, effectively improving oxygen utilization.

The invention discloses a pressure adjusting method and system for double-level respiratory support equipment, and the method comprises the following steps: in the expiration stage of a user, setting expiration positive pressure as initial pressure; detecting the breathing state of the user in real time, and when it is detected that the user enters an inspiration state, performing linear fitting based on the first pressure value to obtain a slope value; a first linear model of the target inspiration positive pressure is established according to the slope value, and the expiration pressure is increased to the target inspiration positive pressure at the initial pressure increasing speed; and in the inspiration stage, the maximum user flow is updated in real time, when the inspiration stage is switched to the expiration stage, a second linear model of the target expiration positive pressure is established based on the maximum user flow, and the target inspiration positive pressure is reduced to the target expiration positive pressure at the initial pressure reduction speed. The technical problem that the pressure boosting or reducing speed of existing bihorizontal respiratory support equipment is too high is solved.

The invention provides an anaesthesia machine and a state recognition method for driving gas of the anaesthesia machine. The anaesthesia machine comprises a breathing loop used for being connected with a patient, a driving gas branch used for providing driving gas for a bellow-free gas driving branch, and the bellow-free gas driving branch with a bellow-free gas driver. The bellow-free gas driver is used for storing driving gas in the inspiration stage and storing gas of the breathing circuit in the expiration stage. The anaesthesia machine obtains the first gas amount flowing into the breathing circuit through the bellows-free gas driver in the inspiration stage and the second gas amount of gas entering the bellows-free gas driver in the breathing circuit in the expiration stage; and determining whether the state of the current driving gas is that the driving gas enters the breathing loop according to the first gas quantity and the second gas quantity. Therefore, a user can know the current state of the driving gas, and the risk that the anesthetic concentration of a breathing circuit is too low is reduced.

A respiratory ventilation system comprises: an air source interface (1), an inspiratory branch (2), a high-frequency inspiratory valve (3), a ventilation control device (4) and an active exhalation device (5); the inspiratory branch (2) is respectively connected to the air source interface (1) and a patient pipeline connected to a patient's respiratory system; the high-frequency inspiratory valve (3) generates high-frequency oscillations in the air in the inspiratory branch (2); the ventilation control device (4) is connected to the inspiratory branch (2), the high-frequency inspiratory valve (3) and the active exhalation device (5); in the inspiratory phase, the high-frequency inspiratory valve (3) is controlled to generate high-frequency oscillations in the air in the inspiratory branch (2) according to a preset high-frequency oscillation frequency, and the high-frequency oscillation gas generated by the high-frequency inspiratory valve (3) is output through the inspiratory branch (2) and the patient pipeline; in the exhalation phase, the active exhalation device (5) is controlled to actively extract the gas exhaled by the patient through the patient pipeline according to the preset high-frequency oscillation frequency. The system is small in size and can reduce gas consumption and noise.

[Problem] In a breath-synchronized breathing gas supply device that supplies breathing gas in accordance with a breathing cycle, a detection error of the start of an inspiration phase caused by the influence of erroneous detection due to the continuous non-detection of inspiration, external disturbance, or the like is reduced. [Solution] The present invention is provided with a pressure sensor and a control unit which determines, as an inspiration detection point, a point at which the value of pressure data calculated on the basis of a signal from the pressure sensor becomes less than an inspiration determination threshold value, and starts the supply of breathing gas. The present invention quickly determines the occurrence of non-detection and erroneous detection of inspiration on the basis of changes in the inspiration detection cycle, and automatically optimizes the determination conditions for inspiration detection corresponding to the current breathing pattern of the user.

The present technology is directed to systems and methods that reduce the amount of oxygen used during high flow therapy. For example, the present technology includes systems and methods that (1) deliver oxygen to the patient during the inhalation phase of a breath at a flow rate between 15 lpm and 60 lpm. and (2) deliver air to the patient during the exhalation phase of the breath at a flow rate between 15 lpm and 60 lpm. Accordingly, the systems and methods can maintain a high flow to the patient during both the inhalation phase and the exhalation phase, but can change the type of gas being delivered to the patient during each phase to conserve oxygen.

An oxygen concentrator system including a pressure swing adsorption (PSA) system that executes a PSA cycle to produce an oxygen enriched gas, a gas outlet airline that flows the oxygen enriched gas to a user of the oxygen concentrator, a cannula that receives breathing gas from the user, and a sensor in communication with the cannula and the PSA system. The sensor senses a breathing cycle of the user. The breathing cycle includes an inhalation phase and an exhalation phase and the exhalation phase includes a non-useful period succeeded by a pre-inhalation period. Each respective breath is immediately preceded in the breathing cycle by a preceding breath and is immediately succeeded in the breathing cycle by a succeeding breath. The PSA system actuates a flow of the oxygen enriched gas via the gas outlet airline after the start of inhalation.

The present application provides a method for detecting airflow limitation events, comprising: obtaining the inspiratory phase peak value and inspiratory phase time corresponding to each respiratory cycle in real time; obtaining a first duration based on the duration of the inspiratory phase amplitude corresponding to each respiratory cycle being greater than a first signal, wherein the first signal is a first amplitude signal obtained based on the inspiratory phase peak value, the first amplitude signal being obtained by multiplying the inspiratory phase peak value by a first preset coefficient, the first preset coefficient being less than 1; comparing the first duration with a first preset time, wherein the first preset time is the proportion of the inspiratory phase time when the inspiratory phase signal is in a normal state; and determining that airflow limitation occurs when the first duration exceeds the first preset time. The technical solution of the present application can more conveniently detect airflow limitation events.

The invention relates to an atomization control method, device and system, atomization equipment and a storage medium. The method comprises the following steps: acquiring a first monitoring signal and a second monitoring signal of a breathing machine, and controlling an atomizer to start atomization under the condition that a breathing state is determined to be an inspiration state according to at least one of the first monitoring signal and the second monitoring signal; and controlling the atomizer to stop atomizing under the condition that the breathing state is determined to be an expiration state according to the running parameters of the breathing machine in the first monitoring signal and any one of the second monitoring signals, or under the condition that the breathing state is determined to be an abnormal state according to the alarm signal of the breathing machine in the first monitoring signal. Therefore, atomization is started only in the inspiration stage, atomization is stopped in the expiration stage and in the abnormal state, medicine waste is remarkably reduced, the effective utilization degree and the corresponding curative effect of medicine are greatly improved, and medical cost and environmental pollution are reduced.

The invention relates to the technical field of ventilation equipment, in particular to a leakage calculation method and system of ventilation equipment, and the method comprises the following steps: when a patient inhales autonomously, determining the flow output of the ventilation equipment by adopting a gradient filtering method, thereby judging whether the flow velocity of the patient end has leakage abrupt change or not; if leakage exists, the next step is carried out; a classical leakage model is adopted, the value of the leakage amount is updated in combination with the motion equation of the patient and the breathing machine, and therefore real-time monitoring and updating of the leakage amount of the breathing equipment are achieved in the whole breathing process. According to the peak flow monitoring and gradient filtering combined method provided by the invention, the abnormal leakage of the inspiratory phase can be quickly monitored, and the leakage rate and leakage parameters of the breathing machine are updated in real time after the flow rate and the pressure signal are stable, so that the leakage rate can be quickly updated in the ventilation process.

This application discloses a method and apparatus for regulating expiratory switching. The method includes: acquiring the user's proximal pressure and the total airflow within the target ventilator during a preset time period of the expiratory phase of the respiratory cycle; determining a predicted user flow rate based on the user's proximal pressure and total airflow; determining a predicted respiratory muscle exertion value based on the predicted user's proximal pressure and user flow rate; and controlling the target ventilator to switch from the inspiratory phase to the expiratory phase in response to the predicted respiratory muscle exertion value meeting a preset condition. Using the user's respiratory muscle exertion as the determination information can accurately reflect the user's voluntary intention to switch between inspiratory and expiratory phases, improving the human-ventilator synchronization during expiratory switching.

The invention discloses a preparation and detection method of a mouse cough model induced by diesel tail gas particulate matters, and belongs to the field of biological medicines. Comprising the following steps: preparing a diesel tail gas particulate matter solution DEP; the method comprises the following steps: anesthetizing a mouse, suspending the mouse in a dissecting plate after the mouse is anesthetized, opening an airway by using tweezers, pulling open a tongue, pinching a nose, observing the breath of the mouse, placing a hose needle into the airway, and injecting a diesel tail gas particulate matter solution DEP into a rear airway of the mouse in a tracheal instillation manner when a gas phase is to be inhaled; observing the breath of the mouse and whether the lung of the mouse has wet rale or not, wherein the injection is successful if the wet rale appears; and putting the mouse back into the cage after resuscitation. The prepared and constructed mouse model can effectively simulate the cough symptom caused by diesel exhaust particles, the mouse model can show a stable cough model after DEP induction, and the mouse model is suitable for clarification of a cough mechanism induced by exposure of real particulate matters.

The invention relates to a method for determining the carbon dioxide concentration in a measurement gas, comprising the following steps: branching off measurement gas from a main line (15) of a medical device (12) via a branch line (14) during the inhalation phase of a person (13) connected to the medical device (12) as inhaled gas and during the exhalation phase of the person (13) as exhaled gas towards a sensor unit (11); conveying the measurement gas from the main line (15) via the branch line (14) towards the sensor unit (11) by means of a fluid conveying unit (24); adaptively setting the fluid conveying unit (24) while taking into account the airway pressure in the main line (15) in order to generate a uniform volume flow and / or gas pressure of the measurement gas in the branch line (14) towards the sensor unit (11) during the inhalation phase and the exhalation phase; and determining the carbon dioxide concentration in the measurement gas by means of the sensor unit (11). The invention further relates to an ascertainment device (10), a medical apparatus (12), a setting unit (26), a computer program product (29), and a memory device (30) having the computer program product (29) stored thereon for carrying out the method according to the invention.

This invention relates to a breath indicator that is receivable by a part of a breathing assistance apparatus that supplies gas to a patient. The indicator comprises an elongate body having a gas sampling end and an attachment end. The attachment end is adapted to attach to a part of a breathing assistance apparatus and for locating the gas sampling end. The gas sampling end is to be located in a region where gas from the patient is to be exhaled. The gas sampling end being in communication with a sensor comprising a detector material changeable between a first visual indicator state relating to an inhalation phase of the patient, and a second visual indicator state relating to an exhalation phase of the patient. The detector material is capable of changing between the visual indicator states at a sufficient rate to substantially correspond with the inhalation and exhalation phases of the patient.

This disclosure provides a ventilator control method and apparatus, a ventilator, a storage medium, and a program product. The ventilator control method includes: acquiring raw diaphragmatic electrophysiological signals of a subject; identifying ECG signals in the raw diaphragmatic electrophysiological signals; determining filter weights based on the deviation between the raw diaphragmatic electrophysiological signals and the ECG signals; filtering the ECG signals in the raw diaphragmatic electrophysiological signals using the filter to obtain a first intermediate signal; reconstructing the first intermediate signal to obtain a diaphragmatic electrophysiological signal to be processed; extracting the envelope curve of the diaphragmatic electrophysiological signal to be processed; and controlling the ventilator to switch between the expiratory and inspiratory phases based on the envelope curve.

An apparatus and process (100) for processing data (101, 102, 103) obtained by an imaging technique enables an improvement of a determination of quality and quantity of ventilation of the lungs. By including a correction data set KDS determined during one or more inhalation phases, it is determined which effects result from adjustments of pressure levels (PEEPA, PEEPB) (81, 82) during ventilation. The result of the determination is provided as an output signal (900).

The invention relates to a respiratory device (10) for artificially respiring a patient (12), wherein a control device (18) is designed to control the flow changing device (16) to perform a P / V action, wherein in an inspiration phase, breathing gas is supplied to the patient (12) while increasing the breathing gas pressure, and in an expiration phase, after the pressure increase has ended, the breathing gas flows passively out of the patient, wherein during the inspiration phase and during the expiration phase, for a plurality of breathing gas pressures, an action-breathing gas volume associated with the currently prevailing breathing gas pressure, which is present in the patient due to the P / V action, is determined. According to the present invention, the control device (18) is configured to: - determine a sequence of compliance values ​​based on the signals of the flow sensor device (44) and the pressure sensor device (27) during the inhalation phase; - determine a reference compliance value based on the sequence of compliance values; - determine a termination compliance value as a criterion for terminating the inhalation phase, based on the reference compliance value, as a threshold value, which is different in magnitude from the reference compliance value; and - terminate the inhalation phase if the termination compliance value is reached or passed.

The present disclosure relates to a ventilation system (1) for supplying an oxygen-containing breathing gas to a patient (3) via a gas delivery line (5), comprising a flow generator (7) for generating a flow of air from an air inlet (11) of the gas delivery line (5) towards the patient (3). The system (1) comprises an oxygen pre-filled chamber (9) arranged downstream of the air inlet (11) such that air from the air inlet (11) flows through the oxygen pre-filled chamber (9) on its way towards the patient (3). The system (1) is configured such that oxygen can be delivered to the patient (3) and the oxygen pre-filled chamber (9) via the oxygen valve (13). The system (1) is able to deliver up to 100% oxygen to the patient (3) by delivering oxygen to the oxygen pre-filled chamber (9) before the start of a high flow period of the inspiration phase, even if the oxygen valve (13) is unable to deliver an oxygen flow matching the peak inspiration flow produced by the flow generator.