BREATH GAS ANALYST FOR EVALUATING BREATH GAS

Description

[0001] The present invention relates to a respiratory gas analyzer for evaluating a respiratory gas.

[0002] Many people suffer from poor sleep, which leads to decreased concentration and reduced mental performance. Poor sleep can also be responsible for disturbances in other functions, such as muscle tone, breathing, heart rate, blood pressure, body temperature, hormones, and metabolism. The causes of poor sleep can be diverse. Poor sleep often results from a sleep disorder in the patient. However, poor sleep can also be present even if no sleep disorder can be identified.

[0003] One possible cause of a sleep disorder can be breathing irregularities (breathing disorders). The most common sleep disorder is obstructive sleep apnea (OSA); in this disorder, the airflow is temporarily either significantly reduced (hypopnea) or completely interrupted (apnea). The resulting lack of oxygen creates a stressful situation that prevents restful sleep and causes heart damage in the medium term.

[0004] In order to be able to make a statement about the extent of a patient's sleep disorder and to treat or correct it accordingly, it is necessary to carry out a sleep diagnosis.

[0005] Sleep diagnostics can be performed using polygraphy devices or ventilators, for example.

[0006] Polygraphy devices are designed to conduct polygraphy. Polygraphy is a procedure primarily used for home diagnostics. The device / measuring device configured for polygraphy is given to the patient to take home. The device / measuring device records information on parameters such as nighttime oxygen saturation, pulse rate, the patient's body position during sleep, and the patient's breathing during sleep, including snoring. Depending on the type of device, the device / measuring device may include an electrocardiogram (ECG) or electromyogram (EMG), which can record the patient's nighttime heart activity or leg muscle activity during sleep. The recorded parameters can be used to determine the extent of the sleep disorder.Furthermore, the function of the ventilators or ventilation therapy can be monitored using the recorded parameters.

[0007] Polygraphy devices are often used in conjunction with ventilators. The ventilators used in polygraphy are configured to perform standard therapies, particularly CPAP (Continuous Positive Airway Pressure), APAP (Automatic Positive Airway Pressure), and bilevel therapy. Some of the described ventilators and therapies, particularly APAP and / or bilevel therapy, can also be configured to record respiratory gas parameters, for example, to determine a patient's required respiratory gas pressure from breath to breath and deliver it to the patient accordingly. For this purpose, the ventilators typically include at least one pressure sensor and / or a flow sensor to determine the respiratory gas pressure or respiratory gas volume.

[0008] The polygraphy and ventilation devices known to date can thus be configured to record respiratory gas parameters and determine the extent of sleep disturbance caused by sleep-related breathing disorders. However, they cannot detect sleep disturbances that are not caused by breathing disorders. Thus, the polygraphy and ventilation devices known to date cannot determine the patient's sleep quality (poor or good sleep).

[0009] In order to be able to determine not only the extent of the sleep disturbance but also the patient's sleep quality during sleep diagnostics, polysomnography is currently required in a sleep laboratory. Polysomnography continuously records information / parameters about the patient's current sleep state and sleep quality using a complex measurement setup in a sleep laboratory.

[0010] Sleep-monitored polysomnography is currently considered the basic instrument and reference method for the diagnostics of sleep disorders. Polysomnography includes, among other things, recordings of sleep-induced EEG (brain wave imaging), EOG (eye movement), EMG (muscle tension), ECG (heart rhythm), respiratory flow, respiratory effort, oxygen saturation, body temperature, body position, and leg movement. Before performing polysomnography in a sleep laboratory, the patient is typically observed for one day to determine their activities and habits. The patient then typically spends two nights in the sleep laboratory.

[0011] The disadvantage of measuring sleep quality using polysomnography is that the polysomnography device is very expensive due to its complex setup. The polysomnography procedure is very time-consuming, as the patient must be admitted to the sleep laboratory for several days. Home use by the patient is therefore not possible. Furthermore, the collected information / parameters can only be evaluated the following day.

[0012] WO 2011 / 006199 A1 discloses a method for determining sleep quality based on the flow signal. For this purpose, the respiratory gas flow is analyzed in great detail to identify defined respiratory events from the flow signal and use them to infer sleep stages.

[0013] EP 2 465 434 A1 discloses a configuration capable of performing a detection test for a comfort level including sleep quality that is measurable at home without requiring the measurement of brain waves or an electrocardiogram.

[0014] It is therefore an object of the present invention to provide a device which is designed to provide a patient or caring professional not only with a statement about the extent of a sleep disorder (sleep-related breathing disorder) of the patient but also with a simplified and direct statement about his sleep quality.

[0015] The subject of the present invention is a respiratory gas analyzer for evaluating a respiratory gas according to claim 1 . Further embodiments are defined by dependent claims 2-9 defined.

[0016] The invention also relates to a method for controlling a respiratory gas analyzer according to claim 10. Further embodiments are defined in claims 11-12.

[0017] Preferred embodiments of the invention are explained in more detail below using highly simplified schematic representations. It shows: Fig. 1 shows a basic structure of a device for ventilation, Fig. 2 shows an exemplary schematic structure of a respiratory gas analyzer according to the invention for determining sleep quality, Fig. 3 shows an exemplary structure of a respiratory gas analyzer according to the invention, Fig. 4 shows an embodiment of a determination of a sleep quality index according to the invention.

[0018] In the figures, the same structural elements have the same reference numerals.

[0019] Figure 1shows the basic structure of a ventilation device. In the area of ​​a device housing 21 of the ventilator 33, with a respiratory gas source in the device interior, there is an operating element 22 and an operating and information system 23 consisting of a display, which can have a, for example, touch-sensitive input unit with at least one control panel. A connecting hose 25 is connected via a coupling 24. An additional pressure measuring hose 26 can run along the connecting hose 25 and can be connected to the device housing 21 via a pressure inlet nozzle 27. To enable data transmission, the device housing 21 has at least one or a plurality of interfaces 28.

[0020] A humidifier can also be adapted. An exhalation element 29 is arranged in the area of ​​the extension of the connecting tube 25 facing away from the device housing 21. An exhalation valve can also be used.

[0021] Figure 1 Furthermore, it shows a patient interface designed as a ventilation mask 30, which is implemented as a nasal mask. Fixation in the area of ​​a patient's head can be achieved via a head cap 31. In the area of ​​its extension facing the connecting tube 25, the patient interface 30 has a coupling element 32.

[0022] Data, such as dead space volume, can be input and / or output via interface 28. The interfaces can be implemented as wired, infrared, Bluetooth, or USB interfaces.

[0023] Preferably, a card slot is also provided. The interface 28 can also be designed as a LAN interface or other interface for connecting to the Internet. An oxygen supply valve can be adapted to the ventilation device in the area of ​​a device housing. It is conceivable to additionally enrich the breathing gas with oxygen to improve patient care. Instead of a single interface 28, a plurality of interfaces can also be provided.

[0024] Via interface 28 – e.g., implemented as a card slot or USB – non-therapy-related data can also be loaded into or executed by the ventilator according to the invention. If the device detects external storage media, the user must confirm a query on the control panel, whereupon the data can be either saved or executed within the ventilator.

[0025] The input and / or output of telemedical data can be performed via interface 28. For this purpose, mobile radio or near-field radio data, WLAN, Bluetooth, or network data, for example, are received / sent via the interface.

[0026] The ventilator 33 is designed to be connected to a patient via a tube and a patient interface 30 to provide ventilation. It comprises a source of respiratory gas, embodied, for example, as an electric motor with a fan wheel, and a device for determining the pressure and / or flow and / or volume of the respiratory gas, as well as a control unit designed to determine a respiratory gas pressure for each respiratory cycle based on a predetermined value for the patient and / or based on measurement signals for the pressure and / or flow and / or volume parameters, and to regulate the source of respiratory gas such that the respiratory gas pressure is generated.

[0027] Figure 2 shows an exemplary schematic structure of the respiratory gas analyzer 10 according to the invention, which comprises a preprocessing unit 12, a buffer 13, an integrator unit 14 and a detector unit 15.

[0028] The respiratory gas analyzer 10 is in a - in Fig. 1 The respiratory gas analyzer 10 can determine at least one sleep stage from the respiratory gas and determine a sleep quality based on the sleep stage.

[0029] The respiratory gas analyzer 10 is configured to obtain at least one respiratory gas parameter from the measuring system 11. For example, a respiratory gas parameter is a respiratory gas volume. The measuring system 11 is arranged externally of the respiratory gas analyzer 10. For example, the measuring system 11 can be arranged in a PAP / ventilator, a diagnostic / polygraphy device, a polysomnography device, or on a patient.

[0030] In the present embodiment, the preprocessing unit 12 is configured to determine at least one standardized value of the respiratory gas volume, for example over a period of 1 minute, based on the referenced respiratory gas volume.

[0031] The buffer unit 13 is configured to buffer the standardized value and make it available to the detector unit 14. The detector unit 14 obtains the at least one standardized value from the buffer and, based on this, determines at least one stability level. The stability level can be determined, for example, by comparing a current value, for example the respiratory gas volume per minute, with a corresponding normalized value of the respiratory gas volume. Preferably, the detector unit is configured to send the determined stability level back to the buffer unit for buffer storage. Based on the at least one determined stability level, the detector unit is configured to classify the sleep state into at least one sleep stage.For example, the detector unit can be configured to conclude that deep sleep occurs when the stability level is above a predetermined threshold value between 0 and 1, for example 0.8.

[0032] The integrator unit 15 is configured to determine a sleep quality based on the at least one sleep stage determined by the detector unit 14. The sleep quality is represented as a sleep quality index. The sleep quality index can be based on the - in Fig. 1The sleep quality index can be displayed on the operating and information system / display 23 shown or on the terminal 20 using a scale between 0 and 100, or as a graphic. The scale is customizable. Typically, a lower sleep quality index indicates poor sleep, while a higher sleep quality index indicates better sleep. The sleep quality index can be provided to the patient and / or a specialist as a numerical value and / or as a graphic.

[0033] The respiratory gas analyzer 10 can be configured to transmit the determined sleep quality index and / or at least one determined sleep stage to an evaluation unit 16 in order to compare and evaluate these with reference values, for example for an age. The evaluation unit 16 can be configured internally or externally of the respiratory gas analyzer. The evaluation unit 16 transmits the at least one evaluated sleep stage and / or the evaluated sleep quality index back to the integrator unit 15. The respiratory gas analyzer 10 is configured to transmit the at least one evaluated sleep stage or the evaluated sleep quality index to the - in Fig. 1 shown - operating and information system / display 23 or by means of an interface 17 to the terminal 20.

[0034] The interface 17 is thus configured to interact with a terminal device 20 in order to display the sleep quality on the terminal device 20. The interface 17 comprises a modem, whereby the respiratory gas analyzer 10 can communicate with at least one terminal device 20 in a network. The interface 17 is generally controllable via the operating and information system / display 23. The interface 17 can be Figure 1 shown interface 28. Based on the determined sleep stage and / or the determined sleep quality and / or the determined stability level, the respiratory gas analyzer 10 is configured to control a polygraphy device / diagnostic device and / or a PAP / ventilator device.

[0035] The Figure 2 The respiratory gas analyzer 10 shown can be used in a Figure 1The ventilator 13 described above can be used. The ventilator 13 is designed for use with a ventilation mask 10 connected via a ventilation tube. The ventilation mask 10 and the ventilation tube 5 can be individually selected. The ventilator 13 can be a ventilator of the CPAP class, the APAP class, or the bilevel class. Optionally, the respiratory gas analyzer 10 according to the invention can be used for a therapy comprising at least three ventilation pressure levels. The respiratory gas analyzer 10 according to the invention is also suitable for use in a diagnostic / polygraphy device.

[0036] Furthermore, Figure 2 an exemplary sequence of the method according to the invention for controlling a respiratory gas analyzer.

[0037] In a first step of the method, at least one respiratory gas parameter is obtained from the measuring system 11 by the respiratory gas analyzer 10. For example, the respiratory gas analyzer 10 obtains a respiratory gas parameter determined by a respiratory gas flow sensor of the measuring system 11, for example, a respiratory gas volume per minute.

[0038] In a further step, the at least one respiratory gas parameter is preprocessed by the preprocessing unit 12 into at least one characteristic value or at least one respiratory gas signal. A respiratory gas parameter could be, for example, a volume of the current breath or a current respiratory rate. Typically, the preprocessing unit 12 determines a standardized value from the respiratory gas volume over a predetermined period of time, for example, one minute.

[0039] In a further step, at least the standardized value, but preferably also the at least one characteristic number or the at least one respiratory gas signal, is temporarily stored in the buffer unit 13. In a further step, the at least one characteristic number and / or the at least one respiratory gas signal are made available to the detector unit 14, for example, over a period of 5 seconds to 5 minutes.

[0040] Typically, the detector unit 14 retrieves the at least one standardized value from the buffer and, based on this, determines at least one stability level. The stability level is determined, for example, by comparing a current value, such as the respiratory gas volume per minute, with a corresponding standardized value of the respiratory gas volume. Typically, the detector unit sends the determined stability level back to the buffer unit for temporary storage. Based on the at least one determined stability level, the detector unit classifies the sleep state into at least one sleep stage.

[0041] In a further step, the integrator unit 15 determines a sleep quality based on the at least one detected sleep stage. For this purpose, the stability levels or sleep stages or sleep stage assignments determined by the detector unit at each time point are summed over the entire night.

[0042] In a further step, at least one of the determined sleep quality indicators is presented as a sleep quality index. The sleep quality index can be calculated from an integral of the curve of the summed stability levels. The sleep quality index can be presented as a numerical value and / or as a graphic. Typically, a lower sleep quality index indicates poor sleep, while a higher sleep quality index indicates better sleep.

[0043] In a further step, the respiratory gas analyzer can transmit the determined sleep quality index and / or the at least one determined sleep stage and / or the at least one stability level to an evaluation unit 16 for evaluation. The evaluation unit 16 analyzes the determined sleep quality index and / or the at least one determined sleep stage and / or the at least one stability level and compares them, for example, with age-typical stored values. Optionally, the evaluation unit 16 can compare the determined sleep quality index or the at least one determined sleep stage with alternative values. Typically, the evaluation unit 16 transmits the assessed sleep quality and / or the at least one assessed sleep stage and / or the at least one stability level back to the respiratory gas analyzer 10.In a further development of the method according to the invention, the respiratory gas analyzer 10 controls a ventilator and / or a polygraphy device 18, 19 and / or a polysomnography device based on the at least one determined sleep stage and / or the determined sleep quality. The determined sleep quality index and / or the at least one sleep stage can, for example, provide feedback on the setting of the - in . Fig. 1 Based on the determined sleep stage and / or the determined sleep quality index, the respiratory gas analyzer 10 can adjust the settings of the - in Fig. 1 shown - ventilator 33.

[0044] The Figure 3ashows an example of a normalized breathing volume. The Y-axis represents a percentage of the normalized breathing volume, and the X-axis represents a time span between 0 seconds and 100 minutes. Figure 3a Normalized respiratory gas volume shown is determined by a - in Figure 2 shown - preprocessing unit 12 with the features described above.

[0045] The Figure 3b shows an example of a determined stability level. The stability level is plotted on the Y-axis with the classification high and low, and a time span between 0 and 100 minutes is plotted on the X-axis. Fig. 3b The stability level shown is determined by a - in Figure 2The integrator unit 15 shown above determines the sleep quality level with the features described above. With a stable respiratory gas volume, the sleep quality level is rather high, while with a fluctuating respiratory gas volume, it is rather low.

[0046] Figure 4shows an exemplary representation of the sleep quality index according to the invention. Shown are a scale a) and a scale b) as well as a pie chart c). Scale a) is divided into a period from 0 to 240 minutes. Scale a) shows the duration of a deep sleep phase or an undisturbed NREM sleep in minutes. Scale b) is arranged correspondingly to scale a) and is divided into percentages from 0% to 100%. Scale b) shows the duration of the deep sleep phase or the undisturbed NREM sleep in percent of an age-standardized target value. The pie chart c) shows a representation of distributions over a certain period in percent. The pie chart is divided, for example, into good, average, and bad days. The Figure 4 The distribution / output of the sleep index according to the invention shown is exemplary. The output or presentation of the sleep quality index is customizable.

[0047] Figure 5shows a preferred classification of the stability level into sleep stages for determining the sleep quality index according to the invention.

[0048] In a first step of the procedure - as in Fig. 2 As shown, the respiratory gas analyzer 10 records and calculates a minute respiratory volume in liters / minute for each breath of a patient using a measuring unit or the measuring system 11. The inspired respiratory volume in liters and the duration of the breath in seconds are recorded and multiplied by 60. This determines the current minute respiratory volume.

[0049] In a further step, an average minute ventilation is calculated and continuously updated. For example, the average minute ventilation of the last 5 minutes is always recorded. Thus, in addition to the current minute ventilation, the respiratory gas analyzer determines an average minute ventilation.

[0050] In a further step, the determined current minute ventilation is normalized to a percentage of the mean value. Thus, the normalized minute ventilation is the minute ventilation divided by the mean minute ventilation multiplied by 100. For example, a mean minute ventilation might be 10 l / min and a current minute ventilation 11 l / min. In this example, the normalized minute ventilation is 110%.

[0051] In a further step, a deflection of the standardized minute ventilation is calculated. According to the above example, a deflection of a standardized minute ventilation of 110% is 10. If the current minute ventilation corresponds to the mean minute ventilation, a deflection of 0 is present.

[0052] In a further step, the deflection is heavily low-pass filtered, e.g., over 2 minutes with a second-order smoothing filter. This reduces the relevance of individual large deflections. The smoothed value indicates how far the deflection was from 0 on average over the last 2 minutes. This is represented as the respiratory restlessness index and corresponds to low-pass smoothing (deflection). The restlessness index is the inverse of the stability level. Depending on the design, a restlessness index (=high value for awake, low value for deep sleep) or a stability level (conversely) is used as the intermediate result.

[0053] In a further step, the current breath is assigned to a sleep stage according to the determined value of the restlessness index (which can only change slowly) or the stability level known from the restlessness index. Fig. 5The restlessness index is divided into the respective sleep stages. The restlessness index is given as a numerical value.

[0054] At the end of a measurement period, for example a night, the time and the proportion of the night in the integrator unit in which the restlessness index was in the deep sleep range, in the light sleep range, in the REM sleep range or in the waking state, etc., are added.

[0055] In a further step, sleep quality is usually determined by the duration of recorded deep sleep or the ratio of the duration of deep sleep to the average age. List of reference symbols

[0056] 10Respiratory gas analyzer 11Measuring system 12Preprocessing unit 13Buffer unit 14Detector unit 15Integrator unit 16Evaluator unit 17Interface 18Diagnostic / polygraph device 19PAP / ventilator 20End device 21Device housing 22Control element 23Control and information system / display 24Coupling 25Connecting tube 26Pressure measuring tube 27Pressure inlet nozzle 28Interface(s) 29Exhalation element 30Ventilation mask 31Headgear 32Coupling element 33Ventilator

Claims

1. A respiratory gas analyzer (10) for evaluating a respiratory gas, wherein the respiratory gas analyzer (10) is configured to obtain at least one respiratory gas parameter of the respiratory gas from a measuring system (11) or comprises at least one measuring unit which is configured to determine at least one respiratory gas parameter from the respiratory gas, wherein the respiratory gas analyzer (10) comprises: - at least one pre-processing unit (12) which is configured to evaluate the at least one determined or provided respiratory gas parameter and to determine at least one respiratory gas signal, wherein the at least one respiratory gas signal is a respiratory gas volume of a current breath and the pre-processing unit is configured to normalize a current respiratory gas volume per breath as a percentage of a normal value of an inspiratory respiratory minute volume of a specific time in order to determine a normalized value, in particular a normalized respiratory gas volume; - at least one temporary storage unit (13) which is configured to temporarily store the normalized value; - at least one detector unit (14) which is configured to determine at least one stage of sleep from at least one temporarily stored normalized value, wherein the detector unit is configured to determine a deviation of the normalized value from the normal value, to filter the determined deviation with a low pass, to reproduce the value smoothed in this manner as a respiratory disturbance index corresponding to the deviation, and to assign a current breath to a stage of sleep according to the determined value of the respiratory disturbance index or according to a stability level as a reciprocal of the respiratory disturbance index; - at least one integrator unit (15) which is configured to determine a quality of sleep based on the at least one stage of sleep determined by means of the detector unit (14), wherein the integrator unit is configured, at the end of a measuring period, to add up the times and proportions of the measuring period during which the respiratory disturbance index was in the range for deep sleep, light sleep, REM sleep, or waking state, and to determine the quality of sleep based on the duration of the detected deep sleep.

2. The respiratory gas analyzer (10) according to claim 1, wherein the respiratory gas analyzer (10) is configured to reproduce the quality of sleep as a sleep quality index.

3. The respiratory gas analyzer (10) according to any one of the preceding claims, wherein the at least one pre-processing unit (12) is configured to evaluate the at least one determined or provided respiratory gas parameter and also to determine at least one characteristic value, wherein the at least one characteristic value is determined from at least one of the following respiratory gas parameters: respiratory gas flow, respiratory gas contour, inspiratory tidal volume, expiratory tidal volume, respiratory rate, respiratory duration, inspiratory duration, expiratory duration, peak flow, leakage.

4. The respiratory gas analyzer (10) according to claim 3, wherein the at least one temporary storage unit (13) is configured to temporarily store the at least one characteristic value, and the at least one detector unit (14) is configured to also determine the at least one stage of sleep from the at least one temporarily stored characteristic value.

5. The respiratory gas analyzer (10) according to any one of the preceding claims, wherein the respiratory gas analyzer (10) is configured to control a polygraph device or diagnostic device and / or a PAP machine or ventilator based on the determined stability level and / or the determined stage of sleep and / or the determined quality of sleep.

6. The respiratory gas analyzer (10) according to any one of the preceding claims, wherein the respiratory gas analyzer (10) is configured to transmit the stage of sleep and / or the stability level and / or a sleep quality index to an operating and information system (22) or to a display (23) of a ventilator (33), wherein the operating and information system (22) or the display (23) is configured to represent the stage of sleep and / or the stability level and / or the sleep quality index.

7. The respiratory gas analyzer (10) according to any one of the preceding claims, further comprising an interface (17) which is configured to interact with a terminal (20) in order to represent the quality of sleep on the terminal (20).

8. A ventilator, comprising a respiratory gas analyzer (10) according to any one of the preceding claims.

9. A device for performing a polygraph and / or a polysomnography, comprising a respiratory gas analyzer according to any one of claims 1 to 7.

10. A method for controlling a respiratory gas analyzer (10) according to any one of claims 1 to 7, comprising the following steps: a. obtaining at least one respiratory gas parameter of the respiratory gas from a measuring system (11) by means of the respiratory gas analyzer (10) or determining at least one respiratory gas parameter from the respiratory gas by means of the at least one measuring unit; b. evaluating the at least one determined or provided respiratory gas parameter and determining at least one respiratory gas signal by means of the at least one pre-processing unit (12), wherein the at least one respiratory gas signal is a respiratory gas volume of a current breath and a current respiratory gas volume per breath is normalized as a percentage of a normal value of an inspiratory respiratory minute volume of a specific time in order to determine a normalized value, in particular a normalized respiratory gas volume; c. temporarily storing the normalized value by means of the at least one temporary storage unit (13); d. determining at least one stage of sleep from at least one temporarily stored normalized value by means of the at least one detector unit (14), wherein a deviation of the normalized value from the normal value is determined, the determined deviation is filtered with a low pass, the value smoothed in this manner is reproduced as a respiratory disturbance index corresponding to the deviation, and a current breath is assigned to a stage of sleep according to the determined value of the respiratory disturbance index or according to a stability level as a reciprocal of the respiratory disturbance index; e. determining, by means of the at least one integrator unit (15), a quality of sleep based on the at least one stage of sleep determined by means of the detector unit (14), wherein the times and proportions of the measuring period during which the respiratory disturbance index was in the range for deep sleep, light sleep, REM sleep, or waking state are added up at the end of a measuring period, and the sleep quality is determined based on the duration of the detected deep sleep; f. representing the quality of sleep as a sleep quality index.

11. The method according to claim 10, wherein the respiratory gas analyzer (10) is a respiratory gas analyzer according to claim 7, further comprising: interacting with a terminal (20) via the interface (17) in order to represent the quality of sleep on the terminal (20).

12. The method according to claim 10 or 11, wherein the respiratory gas analyzer (10) is a respiratory gas analyzer according to claim 5, further comprising: controlling a polygraph or diagnostic device based on the determined stability level and / or the determined stage of sleep and / or the determined quality of sleep.