DE102017111026A1 - Device for measuring respiratory activities of a person - Google Patents

Device for measuring respiratory activities of a person

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Publication number
DE102017111026A1
DE102017111026A1 DE102017111026.7A DE102017111026A DE102017111026A1 DE 102017111026 A1 DE102017111026 A1 DE 102017111026A1 DE 102017111026 A DE102017111026 A DE 102017111026A DE 102017111026 A1 DE102017111026 A1 DE 102017111026A1
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Germany
Prior art keywords
respiratory
characterized
measuring
flow
temperature sensor
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DE102017111026.7A
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German (de)
Inventor
Carla Kulcsar
Yasmina Höher
Otto Thies
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Carla Kulcsar
Yasmina Höher
Otto Thies
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Application filed by Carla Kulcsar, Yasmina Höher, Otto Thies filed Critical Carla Kulcsar
Priority to DE102017111026.7A priority Critical patent/DE102017111026A1/en
Publication of DE102017111026A1 publication Critical patent/DE102017111026A1/en
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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Detecting, measuring or recording for diagnostic purposes; Identification of persons
    • A61B5/08Detecting, measuring or recording devices for evaluating the respiratory organs
    • A61B5/087Measuring breath flow
    • A61B5/0878Measuring breath flow using temperature sensing means

Abstract

The invention relates to a respiration measuring device for measuring the breathing of a person who rests with her head on a head lying surface, with at least one temperature sensor, which is positioned relative to the head position and the Kopwiegfläche opposing the exhalation by a change in temperature at the temperature sensor by him measures passing gas, and with at least one bridge circuit (1) with two voltage dividers having the at least one temperature sensor as a resistor of one of the two voltage divider and the two measuring poles between the voltage dividers, and with an evaluation, each of the two measuring poles of at least a bridge circuit (1) is connected in an electrically conductive manner and the respiratory misfire measures the breathing of the person.

Description

  • The invention relates to a respiration meter for measuring the breathing of a person.
  • Respiratory meters are known in the art. In the WO 2016/027086 A1 is a hand-held monitor for the respiratory pattern of a patient known. A mask is placed on the face of the patient, which should not or only slightly influence the respiratory activities. The disadvantage of this is that the mask remains permanently fixed in position on the face of the patient during sleep in order to influence the air flow of the breath with respect to the sensor located in the mask little.
  • In the US 2010/0145211 A1 For example, there is disclosed a flow meter that also has a mask placed over the patient's mouth and nose. The flowmeter has a filament that is the resistance of a bridge circuit. A voltage signal of the bridge circuit is evaluated by means of an extraction circuit and a detection circuit.
  • In the DE 10 2005 000 964 B3 In particular, there is disclosed a method of measuring a volumetric flow differential finding particular use in a ventilator having a first resistive flow sensor and a second resistive flow sensor, wherein the first resistive flow sensor is disposed in the inflow and wherein the second resistive flow sensor is disposed in the outflow. Disadvantageously, the apparatus is relatively expensive.
  • From the US 4,036,217 is a measuring device with a Heizdrahtememometer known. In the process, electrodes are applied to the patient's chest. Disadvantageously, here too the patient is brought into direct contact with the measuring device.
  • The US 7,533,670 B1 discloses a respiration meter, wherein also sensors are placed on the chest or in the nose and throat area of the patient.
  • The US 8,434,479 B2 relates to a heating wire anemometer in which a mask is also placed on the oral / nasal area of the patient.
  • US 2011/0201956 A1 relates to a measuring device for the diagnosis of physiological parameters of the lung, wherein a bronchoscope is inserted via the trachea into the lungs.
  • In addition, ventilators, for example the EvitaXL from Dräger Medical AG & Co. KGaA, are known, but they are not suitable for monitoring respiratory misfires.
  • Another disadvantage of the respiration measuring devices mentioned is the fact that they have a mask which has to be tightened over the mouth and nose of the patient and must remain there during respiration recording, in particular during sleep. A disadvantage of said respiration measuring devices is that the tightened mask disturbs the sleeping rhythm of the patient.
  • It is therefore an object of the invention to provide an aforementioned respiratory instrument available, which does not have the disadvantages mentioned.
  • The object is achieved by a respiration meter for measuring respiratory activities of a person who rests with his head on a head rest area. The person may be a patient, an adult or a child or a baby, but in principle the device may also be used in animals.
  • The respiratory activities of the subject may be measured in medical, industrial, military or domestic settings during waking, but preferably while the person is asleep. For this purpose, the person conveniently lies on a substantially horizontal lying surface, wherein the head of the person rests on a part of the lying surface, the head lying surface.
  • The respiratory measuring device according to the invention has at least one flow measuring sensor, which according to the invention is position-maintaining relative to the head bending surface and which is arranged opposite the head bending surface. The at least one flow measuring sensor is positioned during the measurement of the respiration of the person, even during sleep of the person and preferably during the entire measurement course positionswahrend against the Kopfliegefläche so that the person can move her head, without the at least one flow measuring sensor is moved. During the measurement, the at least one flow measuring sensor preferably remains stationary in space and position-maintaining with respect to the head area of the head. According to the invention, no mask is required. A mask is not part of the respiratory instrument according to the invention. The respiration meter is maskless. During the measurement of respiration, the person's head is disposed between the head flexure surface and the at least one flow measurement sensor, typically the at least one flow measurement sensor is disposed vertically above the head flexure surface.
  • The at least one flow measuring sensor is preferably attached to a support which may be spaced from and over the head fly surface. The holder may be a preferably horizontally arranged rod. The bar is conveniently attached to a stand standing on the floor or directly to a bedstead in which the person lies. There are also other types of attachment conceivable. Position-preserving is to be understood broadly. The relative arrangement need not be permanently fixed, such as the attachment to the bed frame, but it may also be variable, such as the stand next to the bed frame. During operation, in particular the measurement, the flow measuring sensor is immobile to the head area, despite the possible head movements of the person, especially in sleep.
  • The respiratory measuring device according to the invention is designed contactless to the person. The breath measurements are made without having to touch the person through the device, for example in the form of a mask. Touches independent of the pure respiration measurement such as pulse measurements, etc. are still possible.
  • The at least one flow measuring sensor according to the invention is preferably designed as at least one temperature sensor. It measures temperature changes due to the airflow passing through it when exhaling. The breath flowing past the temperature sensor causes a temperature change preferably at the temperature sensor or in areas of the outer surface of the temperature sensor. Preferably, the existence of respiratory pulses is measured, i. H. it shows the fact whether an inhalation / exhalation has occurred, by sudden temperature change at the temperature sensor. If there is no inhalation / exhalation, no impulses are measured. The respiratory measuring device according to the invention therefore serves in particular for measuring apnea or preventing a sudden infant death.
  • The respiratory measuring device according to the invention comprises at least one bridge circuit with two voltage dividers, which has the at least one flow measuring sensor as a resistor of one of the two voltage dividers and which has two measuring poles between the voltage dividers.
  • In this case, each of the at least one flow measuring sensor is assigned a separate bridge circuit each having two voltage dividers, and each flow measuring sensor is provided as a resistor of one of the two voltage dividers. If the respiration meter has two or more flow measuring sensors and two or more bridge circuits, exactly one separate bridge circuit is assigned to each flow measuring sensor according to the invention, wherein the bridge circuits with their associated flow measuring sensors are essentially identical to one another, preferably of identical construction.
  • According to the invention, an evaluation device is also provided, which is connected in each case to the two measuring poles of the at least one bridge circuit in an electrically conductive manner and measures the respiratory misfires of the person's breathing and preferably signals them.
  • In a preferred embodiment of the invention, the temperature sensor has a measuring element which is completely exposed to the ambient air. It is essential for the invention that the measuring element of the temperature sensor is completely exposed to the ambient air, wherein completely exposed here is to be understood that a breath of the person, at least when the person has their mouth in Atemstromrichtung before the temperature sensor, undisturbed on the measuring element meets.
  • During operation of the respiration measuring device, the measuring element preferably has an operating temperature of more than 100 ° C., preferably between 100 ° C. and 300 ° C. In principle, other operating temperatures are possible. The measuring element is preferably heated to an operating temperature of significantly above the ambient temperature or room temperature, so that the respiratory pulses of the person exhaling, even if the air flow only or only partially passes the measuring element, to a temperature change, preferably lowering the temperature of the measuring element, preferably a Lead area of the measuring element.
  • The change in temperature of only a portion of the measuring element generates an ohmic change in resistance of the measuring element, which is detectable at the temperature sensor as a change in a voltage difference by means of the bridge circuit.
  • The measuring element may be wire coils of conventional incandescent lamps. The wire coils are made of tungsten wire, which has a diameter of 10 to 30 microns. The tungsten wire is usually 99% ± 1% tungsten.
  • However, it is also conceivable to use surface conductively coated carrier as a measuring element, which are brought to an operating temperature above the room temperature.
  • However, it has proven to be particularly preferable to use wire coils of incandescent lamps as temperature sensors by removing a glass bulb of the incandescent lamp. The remaining one Incandescent lamp is screwed with its thread into a conventional socket and forms the tempering sensor.
  • The bridge circuit of the at least one temperature sensor is balanced when the person is not breathing, so no air flow past the temperature sensor, d. H. no voltage can be measured between the two measuring poles of the bridge circuit.
  • In the balanced state flows through the at least one temperature sensor nevertheless a sufficiently strong current to bring the temperature sensor, in particular the measuring element, preferably the wire coil to the above-mentioned operating temperature and to hold. The temperature sensor has a warm resistance in the operating state, which differs sufficiently from the cold resistance.
  • Although the energy stored in the wire helix is very low. For safety reasons, it may nevertheless be provided that the wire helix is surrounded by an air-permeable wire grid, which prevents accidental contact.
  • Preferably, the at least one flow measuring sensor is arranged at a distance of between 10 and 30 cm in front of the mouth of the patient. Any distance between these values is disclosed. But there are also larger distances possible. Of course, the distance varies due to the head movements of the person.
  • In a particularly preferred development of the invention, a resistance of the bridge circuit, which is preferably connected in parallel branch to the temperature sensor, comprises a measuring element of identical construction to the measuring element of the temperature sensor, which, however, is shielded from the ambient air by a breathable air current. The identical measuring element, which is shielded from the respiratory flow in contrast to the measuring element of the temperature sensor, balances longer-term temperature changes in the bridge circuit, for example changes in the room temperature. In this way, long-term temperature changes, both from the at least one temperature sensor and from the at least one identical measuring element, are absorbed in the same way and lead to an equal resistance change and balance the bridge circuit, while the short-term temperature changes caused by the respiratory pulses are only picked up by the at least one temperature sensor while the identical measuring element is shielded from breathing air current.
  • Particularly preferably, the identical measuring element is also designed as a wire helix, preferably as a structurally identical wire helix, the identical wire helix is arranged in a glass bulb and the glass bulb conveniently has a hole with a diameter of 1 to 3 mm, via which the identical wire helix with the ambient air in air-conducting connection stands, but is also shielded breathing air current. Practically, the temperature sensor is therefore formed by an incandescent lamp, from which the glass bulb is removed, while the structurally identical wire coil is arranged in a similar incandescent lamp, in the glass bulb, an above-mentioned hole is introduced breath-tight.
  • Conveniently, a variable resistor is connected in series to set the operating current of the at least one temperature sensor to the bridge circuit. With him the heat resistance of the temperature sensor is adjustable. The heat resistance of the temperature sensor is favorably set to one of the above temperatures.
  • In a particularly preferred embodiment of the invention, a plurality of temperature sensors is provided, which are arranged fixed in position relative to the head surface in each case.
  • It has been found that when using a single temperature sensor, the measurements of the breathing pulses when exhaling the person have different strengths, depending on the position in which the person's mouth is opposite to the temperature sensor. When the breath is directed directly at the temperature sensor, there is a greater temperature change than when the head is tilted sideways and the breath results in less airflow at the temperature sensor.
  • Therefore, according to a development of the invention preferably the above-described construction of a temperature sensor is provided several times. It is provided a plurality of temperature sensors, which is arranged fixed in position relative to the Kopfliegefläche at different locations. It has been shown that it is sufficient for the measurement of respiratory pulses to arrange a plurality of temperature sensors transversely to the longitudinal direction of the body of the person, ie along the direction of rotation of the head or the mouth of the person, since depending on the rotational position of the head at least one of Temperature sensors receives a sufficiently strong exhalation pulse.
  • It has been shown that four temperature sensors are already sufficient to safely detect an exhalation pulse of the person regardless of the head rotation position. It is, however It is conceivable that any higher number or even a lower number of temperature sensors can be used.
  • Preferably, the evaluation device comprises a summation circuit, which adds up the measured values of the plurality of temperature sensors in each case at different and multiple times, preferably continuously. In particular, it can be determined whether or not there is a respiratory impulse.
  • In a further development of the respiratory measuring device according to the invention, weighting factors can be determined by the evaluation device, which can be assigned to the temperature sensors, and the temperature sensors, which are more affected by the air flow during expiration, are assigned higher weighting factors than the temperature sensors, which are less affected by the air flow during exhalation are.
  • This information can be obtained, for example, about the rotation of the head of the person, the frequency of rotation of the head, etc. It can also reduce the background noise. A decision maker is expediently arranged in the evaluation device, which uses the measuring pulses for evaluation only when a minimum value is exceeded, for example. As a result, only the measured values of the temperature sensors arranged directly in front of the mouth of the person are taken into account, as a result of which a movement profile of the head can be detected. The decision maker can also arrange the size of the measuring impulses and determine the weightings accordingly
  • Particularly preferably, the evaluation device comprises at least one analog filter and at least one analog amplifier, which are electrically connected to the two measuring poles of the bridge circuit.
  • Preferably, in the presence of a plurality of temperature sensors, a plurality of bridge circuits, preferably also a plurality of amplifiers and filters is provided, which are each assigned to one of the bridge circuits.
  • To evaluate the voltage signals between the measuring poles of the bridge circuit, the evaluation device according to the invention is provided, which preferably comprises two switched as low-pass filter operational amplifier. The operational amplifiers can be coupled to one another via a high-pass filter. A bandpass filter made up of high and low pass filters is desirably asymmetrical and transmissive to signals with frequencies between 0.15 Hz and 20 Hz. The average and usual respiratory rate is one breath every four seconds, so that the bandpass filter mentioned above would be useful Has. Of course, the bandwidths of the bandpass filter are adjustable and customizable to the individual.
  • Conveniently, the analog amplifier and filter downstream of an A / D converter, which converts the analog measurement signals into digital measurement signals; Digitization has proven to be advantageous for comparing the digital readings with a threshold after digitalization or performing digital filtering. The threshold value is set in such a way that an always present background noise does not falsify the evaluation results. The noise typically produces significantly lower voltage readings than an expiratory pulse. The exceeding of the threshold caused only by the exhalation pulse is registered. The A / D converter is followed by a microcontroller or a digital signal processor (DSP), which compares the digitized measured values with the threshold value and when the threshold value is exceeded, measures a measuring signal regardless of the amount of the overshoot and determines a time interval between successive measuring signals generates a warning signal if the time interval is greater than a predetermined maximum time value. For apnea detection, the time maximum is conveniently set to 12 seconds ± 2 seconds.
  • The invention will be described with reference to an embodiment in twelve figures. Showing:
    • 1 a block diagram of a signal processing according to the invention,
    • 2 a bridge circuit without controllable resistance,
    • 3a . 3b . 3c Voltage measurements of different wire coils at different distances,
    • 4 a graphical representation of the measured values in 3a against 1 / r 2 ,
    • 5a . 5b an analog voltage waveform on the bridge circuit according to 2 simulating exhalation by actuating an air pump,
    • 6 a digitized waveform over time of a person lying on his back and breathing in the direction of the temperature sensor, which is 17cm away,
    • 7 a digitized voltage measurement over time at a person, before the mouth of the temperature sensor is arranged at a distance of 20 cm,
    • 8th a digitized waveform over time, with the person lying on his back and the temperature sensor at a distance of 11 cm to the nose through which he breathes,
    • 9 a schematic diagram of a respiration meter with a plurality of temperature sensors.
  • A problem in this day and age is the sleep-disordered apnea. Affected are about five percent of the population. The consequences of apnea include fatigue, lack of concentration and headache, which can lead to increased cortisol output, permanent stress and respiratory distress to life-threatening situations. To diagnose such situations early and without expensive equipment, the respiratory instrument according to the invention is proposed.
  • The respiration meter has at least one flow measuring sensor for measuring finest respiratory air flows. Apnea is registered as a person's absence of breathing air.
  • The flow measuring sensor for measuring the finest respiratory air flows is designed as a temperature sensor. The temperature sensor according to the invention consists in this embodiment of a wire helix, which is arranged inside conventional incandescent lamps. The ohmic resistance of the wire helix changes due to the temperature change of the wire helix in the breathing air flow. The basic signal processing is shown in a block diagram in 1 shown. The resistance change effects in a bridge circuit 1 , into which the temperature sensor is inserted, small changes in measuring voltage, which are then amplified and filtered highly sensitive in an amplifier and bandpass filter and with the aid of an A / D converter 3 digitized in a datalogger 4 stored and in a diagnostic unit 6 be evaluated. From there, a warning signal is also issued if necessary.
  • An important improvement over conventional respiratory instruments is that the temperature sensor detects respiratory air flows even in the decimeter distance of the mouth and / or nose of the sleeper without contact. Thus, the sleeping person is not touched by the respiration meter by a conventional mask and not disturbed in his sleep.
  • Conventionally, the respiratory rate is 0.2 to 0.25 Hz, in newborns but also at 0.6 to 0.7 Hz. The respiratory volume of an exhalation is usually 0.5 liters, and the breathing pressure is 50 to 100 mbar. The respiratory flow rate is approx. V = 0.8 m / sec.
  • Essential to the invention for the respiration meter is the construction of the temperature sensor. The temperature sensor has a wire coil. A glass bulb of the bulb is removed, and the wire helix is thus completely free. It has complete contact with the ambient air. The wire helix can remain in the lamp thread. The lamp thread is screwed into a conventional lamp socket, and the resulting assembly is used as a temperature sensor.
  • It has proven convenient to bring the wire helix to an operating temperature which is higher than the room temperature. However, the wire coil should not light up, because otherwise it burns. The breathing air stream passing the wire helix cools the heated wire helix and thereby changes its ohmic resistance. For the temperature dependence of an ohmic resistance of wires, the equation applies to small temperature changes Δ R = R 0 αΔ T .
    Figure DE102017111026A1_0001
    where ΔR = R T - R 0 is the temperature-dependent resistance change and R 0 is the resistance at a certain reference temperature. This equation is also approximately used here. In this case, the resistance is given at a temperature of 20 ° C., ΔT denotes the temperature difference with respect to this reference temperature, and α is the linear, positive temperature coefficient of the wire helix. The breathing air passing by the temperature sensor should have a temperature of about 20 - 30 ° C. The breathing air thus leads to a reduction in the temperature of the wire helix, at least on its surface, and thus also to a reduction of the ohmic resistance of the wire helix.
  • The temperature sensor is powered in a bridge circuit described below.
  • The wire helix of the temperature sensor has a cold resistance R 0 , approximately for the heat resistance R T = R 0 ( 1 + αΔT + βΔT 2 ), where β is significantly smaller than α. α is the linear temperature coefficient of tungsten or the material of which the wire helix is made up. The relationship between temperature change and resistance change thus results in: Δ T = R T - R 0 α R 0
    Figure DE102017111026A1_0002
  • For tungsten α = 4.5 10 -3 / ° C and β = 9,62 10 -7 / ° C.
  • The temperature sensor is in a bridge circuit according to 2 installed as one of the resistors R 1 . The bridge circuit is balanced at operating temperature. The currently used operating temperature is around 300 ° C, which is significantly higher than the room temperature. As a result, air flows, which have room temperature, cool the filament and are detected as a change in resistance of the filament. Furthermore, the filament can warm up quickly after cooling. The other resistances R 2 . R 3 . R 4 are dimensioned so that in the operating state, the basic circuit is balanced, so the measuring voltage U Mess = 0 is. In order to determine the current through the temperature sensor branch of the bridge circuit and thus by the heat resistance of the wire coil easier, large resistances for R 3 you R 4 selected, preferably in the kΩ range. Cheap currents are about one quarter to one third of the normal operating current of the bulb.
  • The measuring voltage results in the bridge circuit according to 2 to: U M e s s = U B ( R 3 R 3 + R 4 - R 1 R 1 + R 2 ) .
    Figure DE102017111026A1_0003
    if the ratio of resistors R 1 / R 2 of a voltage divider the ratio of the resistors R 3 / R 4 the other voltage divider corresponds.
  • Three series of tests were carried out using different wire helices as temperature sensors. It was in each case the in 2 shown bridge circuit used for voltage measurement.
  • In the first experimental set-up, a large wire helix of a 60W / 220V incandescent lamp was used with a heat resistance of 71 Ω and an operating temperature of 420 ° C; the measurement results are in 3a shown. The wire helix is a tungsten wire helix. The exhalation was simulated by an air pump. A pump head was installed parallel to and with the air outlet directed at the wire helix. A distance between the wire helix and the pump head was gradually changed by several centimeters, and the measured voltage values U meas were measured as a function of the increasing distance. The first measurement was taken at a distance of 30 cm, and the distance was then increased in 5 cm increments. It is clear in 3a to recognize that the measuring voltage decreases as a function of the distance between the pump head and wire helix, which is due to the decreasing intensity of the air flow with increasing distance from the wire helix. Measurement errors due to external factors, such as draft or the like, can occur as in the measurement at a distance of 40 cm.
  • The measured curve shows that the voltage measurements of the air flows no longer differ significantly from background disturbances at a distance of approx. 55 cm at a measuring sensitivity of 20 mV / cm. It should be noted that the air pump presumably releases stronger and more regular air currents than the normal one.
  • In a second experiment, a medium wire coil of a 3.8V / 0.07A incandescent lamp with a cold resistance of 3.6Ω was used, the measurement results are in 3b shown. The measured voltages are significantly lower, the sensitivity in the second test is 0.5 mV / cm, the wire coil has a hot resistance of 1.97 Ω and an operating temperature of about 250 ° C. Again, the second value is an outlier, which is probably due to other air movements. Clearly, the falling of the measuring voltage with the distance to recognize.
  • In a third experiment, a small wire coil of a 6.7Ω lamp was used. The wire helix has a heat resistance of 6,61Ω, with an operating temperature of approx. 230 ° C. The measurement results are in 3c shown. Again, at a distance of 55 cm an outlier should be present, the trace should be approximately proportional to 1 / r 2 . The voltage readings are in the range of microvolts.
  • In 4 are the readings with the in 2 were measured against the reciprocal square of the distance ( 1 / r 2 ) between the sensor and the airflow source, the linearity of the curve confirms the relationship.
  • The bridge circuit also has a variable resistor R 5 on, with which the electricity I 1 , through the temperature sensor R 1 is adjustable. The current I 1 , is adjusted so that the wire helix of the temperature sensor R 1 assumes the above-described operating temperatures at which the bridge circuit is preferably balanced.
  • The 5a . 5b show the analog voltage curve at the bridge circuit in the simulation of the regular breathing by periodically actuating an air pump. In the 5a the big wire helix is used. In the 5b the voltage curve is recorded using the small wire helix.
  • After the analog experiments described above, the measurement results became digital evaluated. Since the exhalation produces a much weaker signal than the above-used air pump, an amplifier circuit according to 5 used. This or a corresponding amplifier circuit is also used in the respiratory measuring device according to the invention.
  • In the respiration meter, the measurement pulses generated by temperature change between the two measuring poles P 1 . P 2 amplified with a two-stage amplifier circuit. Each of the amplifier stages has an operational amplifier Op1, Op2, each of which is connected as a low-pass filter. The two amplifier stages can be coupled via a high-pass filter. If necessary, the high-pass filter can also be dispensed with.
  • The amplified and filtered signal becomes an A / D converter 3 supplied, and the converted digital signals are fed to a microcontroller or a digital signal processor (DSP) and evaluated there.
  • 6 shows the measurement of a person lying on his back and breathing in the direction of the temperature sensor. The temperature sensor is placed at a distance of 17 cm free in the air hanging in front of the person's mouth.
  • 7 shows the measurement results of a test that simulates a sleeping situation as real as possible. For this purpose, a person sleeps under the temperature sensor, the temperature sensor is located at a distance of about 20 cm from the mouth, the temperature sensor is not vertically suspended above the head in the air, but it is slightly offset to the feet, so that the breathing air flow Exhale as centrally as possible hits the temperature sensor. In the 7 The measured voltage signals shown clearly show the breaths, with each peak representing one breath. Since the measurement was carried out with just one temperature sensor, there are time periods in which the measurement signal is smaller; This can be seen in particular in the rectangular enlarged and marked area in the graphic in 7 , At the beginning of the marked area, the peaks are clearly visible until the person has probably turned. After that, the peaks are no longer recognizable. Before the person turns, the respiratory impulses are clearly visible against the background noise. In the 7 The measured curve shown is used as the basis of a further evaluation for the delivery of a signal tone. A threshold value Usch is set with which the measured values can be easily processed. Thus, the results are not distorted, since noise amplitudes are normally smaller than the atmospheric peaks. The breath peaks are registered with always the same amplitude, the exceeded threshold U sch ; once the threshold is reached, the microcontroller or digital signal processor (DSP) receives a breath signal.
  • 8th shows the digitized readings over time in a test setup with the person lying on his back and the temperature sensor 11 cm away from the nose through which he breathes. The threshold value U sh is determined, which is suitable for distinguishing respiratory misfires from normal breaths, wherein the threshold value U sch lies above a constantly existing background noise. In the present case, a threshold value of U sch = 1,500 mV was chosen. When the threshold value U sh is exceeded, this exceeding is registered as exhalation and a time counter is set to zero. If more than one time maximum value h t of for example t = h 10 s no further exceeding the threshold U sch is carried out, is discharged after the elapse of the maximum value h t a warning sound. This is indicated by a horizontal bar in the 8th shown. The warning tone remains in effect until the threshold U sch is exceeded again.
  • In 9 the respiration meter is shown with a plurality of temperature sensors with associated signals s 1 , ..., s M , where M indicates the number of temperature sensors. The individual measurement signals are in a bridge circuit as in the individual temperature sensor described above 1 measured and in an amplifier and in a bandpass filter 2 amplified and filtered, then into digital signals in the A / D converter 3 converted and subsequently in a digital filter 5 filtered. The individual signals s 1 , ..., s M of the temperature sensors can then be in a summation circuit 10 be summed up.
  • The individual signals s 1, ..., S M can be weighted with weights w 1 to w M , which are determined, for example, as follows: w i = s i Σ j = 1 M s j . i = 1, ... . M
    Figure DE102017111026A1_0004
  • The weights w i are calculated using a comparator 11 certainly. For example, when breathed to the temperature sensor with the signal s 1 is arranged the mouth or nose so in front of the temperature sensor with the signal s 1, s is 1> s 2, s 3, ... s M. The temperature sensor with signal s 1 gives the largest signal. The other temperature sensors with the signals s 2 , ..., s M record either the weakened respiratory signal or only the noise from the environment. In order to minimize the noise components, the signals s i are not evaluated in the same way, but the signals s i are weighted by the differently sized weighting factors w 1,..., W M. The strongest signal, in the present Example s 1 , is the most heavily weighted. By dividing the respective individual signals s i by the sum of all signals Σ j = 1 M s j
    Figure DE102017111026A1_0005
    or the sum of the other signals Σ j = 1 j i M s j
    Figure DE102017111026A1_0006
    the factor w i of the temperature sensor with the largest signal s i will be greatest. Thus, the noise can no longer affect the strongest respiratory signal of the affected temperature sensor with the signal s i so much. It can also be determined beyond information whether respiration is present or not 12, whether the person has turned his head or not 13.
  • LIST OF REFERENCE NUMBERS
  • 1
    bridge circuit
    2
    Bandpass filter
    3
    A / D converter
    4
    data logger
    5
    digital filter
    6
    diagnostic unit
    10
    Summing circuit
    11
    comparator
    12
    information
    13
    information
  • QUOTES INCLUDE IN THE DESCRIPTION
  • This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.
  • Cited patent literature
    • WO 2016/027086 A1 [0002]
    • US 2010/0145211 A1 [0003]
    • DE 102005000964 B3 [0004]
    • US 4036217 [0005]
    • US 7533670 B1 [0006]
    • US 8434479 B2 [0007]
    • US 2011/0201956 A1 [0008]

Claims (18)

  1. Breathing device for measuring the breathing of a person who rests with his head on a head rest area, with at least one flow measuring sensor which is positionally positioned relative to the head bending surface and opposite the head bending surface and which measures an exhalation by a flow change on the flow measuring sensor by the breath flowing past it; at least one bridge circuit (1) with two voltage dividers, which has the at least one flow measuring sensor as a resistor of one of the two voltage dividers and which has two measuring poles between the voltage dividers, and with an evaluation device which is connected in each case to the two measuring poles of the at least one bridge circuit (1) in an electrically conductive manner and measures the respiratory misfires of the respiration of the person.
  2. Respiratory meter after Claim 1 , characterized in that the flow measuring sensor comprises a temperature sensor.
  3. Respiratory meter after Claim 2 , characterized in that the temperature sensor comprises a completely exposed to the ambient air measuring element.
  4. Respiratory meter after Claim 1 . 2 or 3 , characterized in that the measuring element is heated to over 100 ° C, preferably between 100 ° C and 300 ° C in operation
  5. Respiratory meter after Claim 1 to 4 , Characterized in that a switched flow to the measuring sensor in series resistance of the bridge circuit (1) includes an identical to the flow measuring sensor measuring element, the flow of respiratory air-tight from the ambient air is shielded.
  6. Respiratory meter after Claim 1 to 5 , characterized in that the measuring element is designed as a wire helix.
  7. Respiratory meter after Claim 6 , characterized in that a structurally identical wire helix is introduced into a glass bulb.
  8. Respiratory meter after Claim 7 , characterized in that the glass bulb has a hole through which the suitable wire helix is in air-conducting connection with the ambient air.
  9. Respiratory instrument according to one of Claims 1 to 8th , characterized in that the bridge circuit (1) is connected in series with a variable resistor, with which a heat resistance of the temperature sensor is adjustable.
  10. Breathing device according to one of the preceding claims, characterized in that a plurality of flow measuring sensors is provided, which is arranged fixed in position in each case relative to the head fly surface.
  11. Respiratory meter after Claim 10 , characterized in that the flow measuring sensors are arranged transversely to the head bending surface side by side and the head bending surface opposite.
  12. Respiratory meter after Claim 10 or 11 , characterized in that the evaluation device comprises a summation circuit (10) which sums the measured values of the plurality of flow measuring sensors in each case at different times.
  13. Respiratory meter after Claim 12 , characterized in that in the evaluation weighting factors can be determined, which are attributable to the flow measuring sensors, and temperature sensors that are more affected by the air flow during exhalation, higher weighting factors are assigned as flow measuring sensors that are less affected by the air flow during exhalation.
  14. Respiratory instrument according to one of Claims 1 to 13 , characterized in that each of the flow measuring sensors is a resistor of each one of the bridge circuits (1).
  15. Respiratory instrument according to one of Claims 1 to 14 , characterized in that the evaluation device comprises at least one analog filter (2) and at least one analog amplifier, which are electrically connected to the two measuring poles of the bridge circuit (1).
  16. Respiratory meter after Claim 15 , characterized in that the at least one analog amplifier, an A / D converter (3) is connected downstream, which converts the analog measurement signals into digital measurement signals and a digital filter (5) is connected downstream.
  17. Respiratory meter after Claim 16 , characterized in that the digital filter (5) is designed as a low-pass filter whose cutoff frequency is below 50 Hz.
  18. Respiratory instrument according to one of Claims 15 to 17 , characterized in that the evaluation device comprises a microcontroller (7) which supplies the digitized measured values with a Threshold compares and registers a measurement signal when the threshold is exceeded, and determines a time interval between successive measurement signals and generates a warning signal when the time interval is greater than a predetermined maximum time value.
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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4036217A (en) 1975-03-31 1977-07-19 Tokyo Shibaura Electric Co., Ltd. Device for measuring a respired amount of air
WO2002062282A1 (en) * 2001-02-06 2002-08-15 Hill-Rom Services, Inc. Infant incubator with non-contact sensing and monitoring
DE10133120C2 (en) * 2001-07-07 2003-09-04 Draeger Medical Ag Hot-wire anemometers
DE102005000964B3 (en) 2005-01-07 2006-07-06 Dräger Medical AG & Co. KG Apparatus for measuring a flow quantity difference between an inspiratory incoming flow and an expiratory outgoing flow in a breathing apparatus using the ouputs of a voltage splitter
US7533670B1 (en) 2005-09-20 2009-05-19 Breathe Technologies, Inc. Systems, methods and apparatus for respiratory support of a patient
US20100145211A1 (en) 2008-12-05 2010-06-10 Nihon Kohden Corporation Gas flow system, meter, and method
US20110201956A1 (en) 2008-05-01 2011-08-18 Alferness Clifton A Direct lung sensor systems, methods, and apparatuses
US8434479B2 (en) 2009-02-27 2013-05-07 Covidien Lp Flow rate compensation for transient thermal response of hot-wire anemometers
US20150309067A1 (en) * 2014-04-23 2015-10-29 Beijing Funate Innovation Technology Co., Ltd. Hot wire anemometer
WO2016027086A1 (en) 2014-08-20 2016-02-25 Sheffield Hallam University Respiration monitoring apparatus

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4036217A (en) 1975-03-31 1977-07-19 Tokyo Shibaura Electric Co., Ltd. Device for measuring a respired amount of air
WO2002062282A1 (en) * 2001-02-06 2002-08-15 Hill-Rom Services, Inc. Infant incubator with non-contact sensing and monitoring
DE10133120C2 (en) * 2001-07-07 2003-09-04 Draeger Medical Ag Hot-wire anemometers
DE102005000964B3 (en) 2005-01-07 2006-07-06 Dräger Medical AG & Co. KG Apparatus for measuring a flow quantity difference between an inspiratory incoming flow and an expiratory outgoing flow in a breathing apparatus using the ouputs of a voltage splitter
US7533670B1 (en) 2005-09-20 2009-05-19 Breathe Technologies, Inc. Systems, methods and apparatus for respiratory support of a patient
US20110201956A1 (en) 2008-05-01 2011-08-18 Alferness Clifton A Direct lung sensor systems, methods, and apparatuses
US20100145211A1 (en) 2008-12-05 2010-06-10 Nihon Kohden Corporation Gas flow system, meter, and method
US8434479B2 (en) 2009-02-27 2013-05-07 Covidien Lp Flow rate compensation for transient thermal response of hot-wire anemometers
US20150309067A1 (en) * 2014-04-23 2015-10-29 Beijing Funate Innovation Technology Co., Ltd. Hot wire anemometer
WO2016027086A1 (en) 2014-08-20 2016-02-25 Sheffield Hallam University Respiration monitoring apparatus

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