Device for simultaneous diagnosis and quantitative analysis of apnea and other diseases.

p0001The invention relates to a device for ambulatory detection and diagnosis of sleep apnea syndrome, comprising a mobile device and a computer. In this case, it is detected by means of the mobile device, the physiological parameters heart rate, breathing sounds and snoring sounds of the patient, stores a plurality of respective detected for short time intervals sets of said parameters in encoded form in the mobile device, it transmits to the computer and analyzes it with its Support, in particular temporal variations of the individual variables and correlations between the different variables are taken into account.

p0002The symptom of sleep apnea is characterized by the coincidence of a respiratory failure, a considerable hypoxemia (ie a reduction of the oxygen content in blood artiellen) and cardiac arrhythmias. Following an episode of apnea, it usually comes to a violent gasp, often to a startling awakening (see, eg, MJ Tobin, MA Cohn, MA Sackner: Breathing abnormalities during sleep, Arch Intern Med 1983; no.... 143, pp 1221-1228).

p0003Increasingly, the epidemiological significance of sleep apnea is detected; it is known that long and frequent apnea phases during sleep often accompany cardiovascular and cardiopulmonary diseases and with profound psychophysical changes. Effects of sleep apnea are daytime an excessively increased tendency to fall asleep (here sleep apnea is statistically identified as the most common) and the occurrence of initiating and maintaining sleep (here is the Sleep Apone described as the fifth most common cause (RM Coleman, HP Roffwarg, SJ Kennedy: Sleep-wake disorders based on polysomnographic diagnosis A national cooperative study JAMA, 1982; No. 247, p 997-1003))....

p0004For a long time are used in specialized clinics, where a diagnosis means polysomnigraphischer evaluations can be performed during sleep for the study of sleep-wake disorder sleep laboratories. These studies are costly and time consuming; they can only be performed in a hospital stay of the patient because of the multitude The male parameters. Because of the widespread occurrence of sleep apnea, a very large number of patients must be analyzed, which is hardly possible in stationary sleep laboratories. In addition, such a stationary investigation has the disadvantage that the sleep of the patient is disturbed by the strange environment. This reduces the meaningfulness of such investigations. Therefore, there has been a number of efforts to overcome the disadvantages of a stationary investigation.

p0005One possibility is an outpatient to recognize the sleep apnea syndrome, avoiding inpatient examinations in sleep laboratories using mobile recording and storage devices and diagnose. Thus, European Patent Application 0,371,424 describes a method and apparatus for ambulatory detection and diagnosis of the sleep apnea syndrome in accordance with the type mentioned above. Here are heart potentials (dhEKG potentials), measured with two to be attached to the upper body of a patient electrode relative to a third electrode and supplied to a peak detector. From the time intervals between the peaks of the heart rate is determined. The breathing and snoring sounds are picked up by a to be affixed on the larynx of the patient electret microphone and fed to two different threshold detectors, wherein a threshold detector over the entire frequency range (approximately 100 Hz to 15 kHz) and the other by attenuating the high frequencies of the signals with a filter only in a lower, typical for snoring frequency range (about 100 Hz to 800 Hz) is sensitive. The threshold detectors respond when the incoming signal exceeds the set thresholds. The thresholds are set so that is detected by the first-mentioned threshold detector normal breathing, the second named snoring. These physiological parameters, namely heart rate and presence or absence of breathing and snoring are measured together at time intervals of 1 s, and binary for each time interval encoded in an in-apparatus RAM memory. The stored during a sleep period data is transmitted from the mobile device into a computer, and analyzed on the computer in terms of a sleep apnea syndrome. From the temporal changes in heart rate, the respiratory and snoring sounds and the correlations between these variables indications of the presence of an apnea can be derived.

p0006The severity of apnea depends on the frequency of incidents, of their depth and duration. The method described with the described device does allow to prove the existence of an apnea event and its duration with great sensitivity. However, the specificity of the diagnosis, which can be achieved thereby is inadequate. The depth of apnea episodes is not exactly determined. Information about the body position of the patient, which is important for diagnosis, such as to distinguish between an upright or lying position of the patient or to a function of the occurrence of an obstruction of the body position does not exist. In pathological conditions such as polyneuropathy, rigid age heart or diabetes, the heart rate does not vary, as otherwise with apnea incidents, strong, but remains nearly constant. In the presence of such conditions, an apnea, in the absence of differential diagnostic possibilities, such as the knowledge of the oxygen saturation of the blood, is difficult to be diagnosed. In many cases, therefore, a subsequent investigation remains stationary when the known in the prior art apparatus necessary in a sleep laboratory.

p0007The invention is therefore based on the object to provide a device for ambulatory detection and diagnosis of sleep apnea syndrome, with such a high diagnostic reliability can be achieved by stationary follow-up in a sleep laboratory is usually not necessary. The device should this addition to the determination of the frequency and duration also allow a quantitative determination of the depth of apnea events and detecting the body position of the patient. An apnea diagnosis should be possible even with the above pathological changes; conversely should in ignorance of their presence hints can be obtained in this state.

p0008This object is achieved with a mobile device of the initially mentioned type, with which it also stores to the other sensed and stored values ​​will be recorded and encoded in synchronism the oxygen saturation level of the blood and the body position of the patient. The stored sets of these variables can with those of other sizes are together transferred to a computer and analyzed with its help, being in the analysis of the duration and depth of periods of oxygen desaturation gaining a measure of the severity of individual apnea episodes and one from changes in body position derives a measure of the apnea-induced sleep disturbance.

p0009Advantageously, one can distinguish in the analysis by means of a function of the occurrence of intermittent snoring, cyclical variations in heart rate and oxygen desaturation during apnea incidents between obstructive apnea, central apnea and some other sleep disorders such as myoclonus. In obstructive apnea the incidents occur more frequently in the supine position. In general, an episode of apnea leads to a strong variation of heart rate and oxygen desaturation of the blood. If one observes however desaturation at nearly constant Herzfreqeunz, one can interpret this as an indication of a polyneuropathy, a rigid age heart, diabetes or a heart attack risk. To improve the quality of diagnosis is beneficial features special occurrences that could disrupt undetected in the analysis, such as lying down, waking or rising, and quantifies the time spent in bed time. This can be done by, in addition to press the current registration of the body position of the patient in such an event to a located at the mobile device pressure switch. From measuring the time course of oxygen desaturation of the blood, the duration and severity of apnea incident can be determined; It is therefore not necessary in determining the duration of the breath sounds. Instead, advantageously only the heavy snoring sounds may be detected that occur when you gasp for a episode of apnea.

p0010The inventive mobile device comprises means for detecting the heart rate, breathing and snoring sounds, the oxygen saturation level of the blood and the body position of the patient at short time intervals, Moreover, the device has means for storing a plurality of sets of signal values ​​in coded form. The apparatus may further comprise means for identification of certain acquisition time intervals, preferably this is a pressure switch. The detection time intervals can be chosen for different lengths for the various male and storing sizes; preferred settings are from 1 to 10 seconds. In another preferred embodiment, shorter intervals down to 0.1 s can be realized. In another embodiment, the length of the detection time intervals is variable, namely, the length from the mobile device be automatically adjusted as required. Especially short time intervals are selected from the device if a particularly dignified gathering events, so there is about a possible episode of apnea.

p0011The means for measuring the oxygen saturation level of blood comprise at least one light source and at least one light receiver, which are fixed to an extremity of the patient and used to measure the extremity effected by the light absorption or reflection of light. When (the) light source (s) may be, for example, (a) light emitting diode (s) and where (the) recipient (s) involve (a) phototransistor (s). The wavelength of the light radiation used is preferably selected so that the associated with a change in the oxygen content of the blood change in color of the blood is optimally visible; this is the case in the area of ​​the red light. If one uses light of two different wavelengths, the second light radiation used is preferably selected such that their reflection or transmission properties of the oxygen content of the blood are as independent as possible; this is the case in the region of infrared light. The light of the second wavelength is used to get an independent reference value of the oxygen content with which the transmitted or reflected light is sensitive to the oxygen content of the light radiation can be normalized. If the measurement of the color change in absorption, as light source (s) and the light receiver are preferably arranged opposite to a mounting element, said light emitting (s) and light receiving (n) side (s) of the light source (s) or of (the) light receiver facing each other. In a preferred embodiment, wherein the fastener is a clip, said light source (s) and the light receiver are arranged on opposite ironing of the clamp. In another preferred embodiment, wherein the fastening element is a flexible bar which is bent at one end of U-shaped, with light source (s) and the light receiver are fixed to the legs of the "U". In both embodiments, the fastener is fixed to the extremity of the patient, that the body tissue between the (the) light source (s) and is (the) light receiver (s).

p0012The means for detecting the spatial position of the patient preferably include a to be fastened on the upper body of the patient hollow body having therein a ball of electrically conductive material. Advantageously, it is at the hollow body is a hollow tetrahedron, are attached to the corners through the ball closeable electrical contacts. The hollow tetrahedron can for example be oriented so that in the supine position, lying on the left and right side and in an upright position, the ball comes to rest in each case in a corner where it closes the contact. In the prone position the ball remains in an area of ​​the tetrahedron and is no contact. the means for detecting the respiratory sounds are advantageously arranged so that they absorb only that violent snoring noise when gasping for a episode of apnea. This can be done, that the threshold of the sensitive over the whole frequency range threshold detector is set high. The measures provided for detecting the heart rate, breathing and snoring sounds, the oxygen saturation of the blood and the patient body position transducers are attached to the patient's body and preferably connected to the mobile device via signal wires. In another preferred embodiment, the signals of these transducers can be wirelessly transmitted, for example, by electromagnetic waves, to the mobile device. In this case, eliminates the need for the mobile device to be attached directly to the body of the patient. Instead of a located at the mobile device the pressure switch to identify special events can then be used also a wireless remote controlled switching device.

p0013As the above shows, the invention has the advantage that a determination of the severity of apnea episodes and thus a quantitatively accurate analysis of the sleep apnea syndrome is possible by measuring the oxygen saturation level. The different combinations of the occurrence of snoring and changes in heart rate, oxygen saturation and body position allow a determination of sleep disturbance and a diagnostic distinction between apnea, hypopnea, myoclonus and other sleep disorders. Furthermore, apnea episodes also in pathological conditions in which the heart rate remains virtually constant, to be diagnosed; the discovery of such conditions is possible. Overall, the invention thus provides over the prior art significantly improved and advanced diagnostic capabilities of the sleep apnea syndrome ready. It was found that the data obtained by the device according to the invention have such a high significance that could be dispensed with in the majority of subjects according to the information by authorized specialists for further investigation. Despite their simplicity, can therefore with the inventive device diagnoses are drawn up with reliability with which stationary long-term studies in sleep laboratories are comparable, but the falsifying influences of hospitalization are not present in a sleep laboratory.

p0014Using the following figures, an exemplary embodiment of the invention in more detail<ul><li>described.</li><li>In the drawing:</li><li>figure 1</li><li>a perspective view of a mobile</li><li>Detection and storage device;</li><li>figure 2</li><li>a perspective view of the device</li><li>in working position on a patient's body;</li><li>figure 3</li><li>a side view of an oximeter sensor with</li><li>a rigid finger clamp for detecting the</li><li>Oxygen saturation content with light absorption measurement;</li><li>4 shows a side view of another embodiment of an oximeter sensor corresponding to Figure 3, but with a flexible rail instead of a rigid clamp.</li><li>Figure 5 is a schematic diagram of the recording and storage device;</li><li>Figures 6 and 7 are graphical representations of detected quantities at various sleep disturbances, shown as a function of time.</li></ul>

p0015. The detection and storage device 1 in Figure 1 consists of the actual recording and storage device 2 with a front-side pressure switch 7 and following different transducers: three EKG electrodes 3, a laryngeal microphone 4, an oximeter finger sensor 5 'a Lageaufnehmer 6 and two connecting cables 8, 9 each with a plug.

p0016In FIG. 2, the positioning of the transducer is shown the body of a patient 10.

p0017The ECG electrodes 3 are commercial disposable electrodes that are attached to the upper body of the patient 10; two of them measure cardiac potential (ECG potential) relative to the third electrode. The throat microphone 4 is an electret microphone which is attached to an annular band 24 the patient's neck 10 that it rests against the larynx. The larynx of the patient 10 adjacent side of the microphone 4 is provided with an annular insulating cushion layer and an annular self-adhesive disposable protective.

p0018In Fig. 3 one embodiment of a finger sensor 5 is shown. It comprises two rigid clamping bracket 11, which are connected by a resilient web 29th On one side of the web 29 a compression spring 15 is arranged between the clamping straps 11, through which the clamping brackets 11 are pressed to each other on the other side of the web for clamping a finger 14 of the patient's 10th On the upper clamping bracket 11 are two light emitting diodes 12, and placed on the lower two photo-transistors. 13 A portion of the 12 emitted from the light emitting diodes light passes through the finger 14 and is received by the phototransistor 13, and another part is absorbed by the tissue of the finger. This absorption measurement is performed at wavelengths 660nm and 925 nm, the absorption of light at the first wavelength is highly dependent on the oxygen content of the blood. the absorption of light of the second wavelength, however, is almost independent thereof.

p0019Another embodiment of a finger sensor 5 is shown in FIG. 4 It comprises a flexible rail 30 which is bent at one end of U-shaped. At the end of the free leg 31 of the "U" two light emitting diodes 12 are arranged. On the other leg located opposite two phototransistors 13. The U-shaped rail 30 is pushed from the front over the top of the finger 14th A fixation of the finger sensor is performed using one or more bands, the ring around the finger 14 and the U-rail 30 laid. In the tapes, it may be tapes with velcro or to disposable tapes. With respect to the light used and its absorption properties similar to this embodiment, the embodiment of FIG. 3. The two embodiments described the finger sensor 5 can be created easily positioned and correctly by laymen. The embodiment of FIG. 3 provides a particularly easy and fast attachment, while the embodiment of FIG. 4 is a particularly secure fixing and because it does not put pressure on the finger, provides a comfortable fit. The Lageaufnehmer is fixed in a particular orientation, which is determined by an external printed label position with an adhesive ring on the upper body of the patients 10th The Lageaufnehmer 6 comprises a hollow tetrahedron having therein a ball of Electrically conductive material in the corners of which are arranged closable by the ball electrical contacts. The hollow tetrahedron is oriented so that at supine position, lying on the left side, the right side and in an upright position, the ball comes to rest in each case in a corner where it closes the contact; Prone the ball remains in an area of ​​the tetrahedron and is no contact. The leading from the microphone, the ECG electrodes 3 and the cable connection Lageaufnehmer 6 are combined to form a single connection cable 8, which can be connected by means of a multipolar connector with the device 2nd The finger sensor 5 has to connect to the device 2 via a private connection cable 9 with another multi-pin connector.

p0020The collection and storage device 2 has such small dimensions (190 x 135 x 45 mm) and such a small weight (about 700 g) that it can be worn with a shoulder strap 25 invisible under clothing on the body. The device 2 has its front side on two multi-pole connectors 26, 27, into which the corresponding connectors of the connection cables 8, 9 can be inserted and secured. In addition to the pressure switch 7 four LEDs 28 are on the device 2 also arranged for function control of the device 2 after the application. To transfer the stored Since th to a computer, a not-shown data transmission cable is provided. Power is supplied either from six small batteries with 1.5V or equivalent batteries.

p0021. The schematic diagram in Figure 5 illustrates the signal processing in the acquisition and storage device 2. The signals picked up by the microphone 4 are amplified by an amplifier 16 and is branched into two channels; the signals of one channel are then passed through a filter 17th The filter 17 attenuates signals above 800 Hz with a Oktavdämpfung of 12 dB. Not shown are the unfiltered branch and provided for both channels threshold detectors. The connected to the filter 17 sensitive in typical for snoring frequency range of approximately 100 Hz to 800 Hz threshold detector is set to an intermediate threshold value, in such a way that the signals of normal snoring sounds, but not by soft breathing sounds exceed the threshold. The second, responsive to the whole frequency range of approximately 100 Hz to 15 kHz threshold detector is set at such a high threshold that this will only be exceeded in general signals that result from the very loud snoring and air snap sounds according to one episode of apnea. The information "is exceeded or non exceed the thresholds" already constitutes a suitable for storing and Weiterverareitung binary size.

p0022The sums provided by the phototransistors 13 of the finger sensor 5 signals are first amplified by a signal amplifier 20th the oxygen saturation level of the blood is then determined and binary coded in a Entsättigungsanalysator 21st The signal levels corresponding to the intensities of the light transmitted through the tissue of the finger 14, the light emitted by the photodiodes 12 wavelengths of light. Since the absorption of the shorter wavelength light depends greatly on the oxygen content of arterial blood, that of the longer wavelength light contrast hardly depends on the oxygen content can be calculated from the signal level of the shorter wavelength light after standardization to the signal level of the longer wavelength light a measure of the oxygen saturation of the blood derived. An accuracy of up to 2% is achieved.

p0023The originating from the ECG electrodes 3 signals are first amplified by an ECG amplifier 18 and then a Herzfrequenzanalysator 19 are supplied. The gained there values ​​of the heart rate are binary coded.

p0024The four possible, stemming from Lageaufnehmer 6 position signals are analyzed in a Lageanalysator 22 and also in binary code. Not shown in Fig. 4, the pressure switch 7.

p0025All these sizes are continually added in parallel, coded and sequentially in time sets together quantitative impaired sizes in a RAM memory 23 with at least 128 kB memory stored. The basic scanning interval amounts to 1 s; the value of the oxygen saturation is every 2 s, every 10 s was added and renewed for the body position. The recording time is at least 22 h. The stored data of a recording period can be transmitted via a non-shown interface unit with a transmission rate of 9200 baud via an RS232 interface XT a not-shown or AT personal computer. By use of memory devices of higher capacity and a total storage capacity of several megabytes can be realized. Thus shorter sampling intervals or longer total recording time can be set.

p0026When starting up at the beginning of a recording period of the connection cable 8 is first triggered automatically to the device 2 a functional check terminal. It takes several minutes and is performed with the aid of light-emitting diodes 28th In this case, one of the light-emitting diode 28 is provided for monitoring the ECG function, the saturation measurement and the two sound channels each breath. The ECG-channel LED assigned is triggered by detection of an R wave, and flickers so when a function in sync with the R-wave on. The oxygen saturation channel assigned LED lights up during the first 30s of the function check, if no valid value is available; This is for instance the case when the finger sensor is not attached in the correct position on the finger. When functioning properly, this LED remains off. Both the respiratory sound channels associated LEDs light up when the respective threshold is exceeded. When functioning properly, these two LEDs are thus extinguished in the normal state, and can be made to light up by simulating snoring noises or very loud breathing noises. After the function test the unit 2 starts recording and storing the physiological data referred to for the duration of a data collection period. After completion of a data acquisition period, the data stored in the mobile device 2, data can be transferred for evaluation to a computer. When evaluating the data can be processed and displayed in three different ways:<ul><li>1) The measured quantities (breath sounds, heart rate, oxygen saturation, body position) are each plotted as a function of time for the entire sample period. This diagram shows quantitatively the common temporal evolution of this size and thus in particular also the correlations between them. (In this case, a compressed (eg 2h / track) or a fully expanded representation (eg 10 min / track) are selected.) It has the advantage of containing the entire recorded information; However, their interpretation requires a certain amount of time.</li><li>ii) Individual measured variables are temporally organized and displayed in the form of histograms and tables. Intended for example are a graph showing the distributions of the measured heart rate values ​​in successive 10 minute intervals, a graph showing the distribution of the measured oxygen saturation values, and representations of desaturation as a function of the duration and frequency of their occurrence in the form of charts and tables. These representations do not have the entire time evolution and all correlations between the measured variables clearly, but allow for faster interpretation.</li><li>iii) From the data, the number of episodes in which probably existed an episode of apnea is directly determined and expressed as an index size of the unit episodes / hour. There are provided three such index sizes: The snoring index, heart rate variation index and the Sauerstoffentsättigungsindex. It was found that at least two coincident index sizes are a "apnea index" equivalent.</li></ul>

p0027To calculate the index are snoring snoring pauses that take s 11-60, counted over the entire measurement period and divided by the number of hours the collection period. Snoring breaks this length are typical of apnea episodes.

p0028To determine the heart rate variation index is a relative heart rate is first calculated by dividing the instantaneous heart rate by the running average of the heart rate of the preceding 300 seconds. Values ​​of the relative heart rate between 90% and 109% are assigned to the so-called 100% class; Other values ​​are outside this class. The heart rate variation index indicates the number of events in the collection period, in which the relative heart rate leaves the 100% class and see returns within 11-60 in the 100% range, divided by the number of hours the collection period. Thus the heart rate variations are detected as they occur synchronously to Apno-Done.

p0029For determining the index Sauerstoffentsättigungs the basal saturation value is first determined by the highest oxygen saturation values ​​are added 2 to 10 previous measurements and the sum by the number of measurements is divided. A desaturation phase is present when the saturation level decreases by at least a predetermined value from the basal saturation level and lasts until a certain return saturation value is achieved in the rebound after the fall. The Sauerstoffentsättigungs index indicates the number of Entsättigungsphasen the acquisition period, divided by the number of hours the collection period. He detects the Entsättigungsphasen as they also occur synchronously to apnea events.

p0030All three index quantities directly to the number of incidents per hour. In a obstuktiven sleep apnea the three indexes sizes have approximately the same value. Large discrepancies between the three index variables may provide information concerning the existence of special pathological changes, as mentioned earlier. Overall, the specification of the three index sizes allow extremely rapid and significant evaluation of apnea events.

p0031Figures 6 and 7 show the raw data representations of snoring, heart rate and oxygen saturation signals. In Figure 6 these signals are recorded at intervals of 10 minutes in Figure 7 of two hours. Shown are the signals each for different diagnosable by the invention sleep disorders. The curves shown are a representation of the stored raw data; they can be drawn on the basis of the stored data in a simple manner. They allow physicians to review the different index sizes with high resolution. They also represent an easily interpretable basis for various diagnoses.

p0032A deep track in the snore signal is a signal of low intensity. A hilltop track represents a noise level which exceeds a certain threshold. Changes in body position are also shown; for simplicity, this has been omitted in the figures. The representation of the two-hour intervals is useful in order to obtain an overall picture. Thus intervals can be identified in which a close examination is mounted.

p0033In a healthy subject the three subscribed variables yield a uniform image. Repeated oxygen saturation, changes in heart rate and snoring does not occur. A It can be derived wake of a sudden increase in heart rate and changes in the (not shown) body position.

p0034In a patient with obstructive sleep apnea (OSA), the three subscribed variables show a cyclic pattern. In OSA, the following three events occur always together on: In intervals in which no breathing sounds are detected, the heart rate decreases and oxygen desaturation occurs. A resumption of breathing is characterized by explosive snoring, along with an increase in heart rate and an oxygen saturation return. It occurs only a few changes in body position, which is typically a supine position.

p0035The free intervals between snoring signal groups represent the apnea intervals. In some cases, the snoring signal groups that appear at the resumption of breathing, but not separated by completely open spaces. Rather, there is a pattern of equally spaced black snoring signal points appear. This pattern represents an obstructive apnea Hypo with a significant narrowing of the upper airways, and should not be confused with continuous snoring.

p0036In a patient with central apnea typically occurs no snoring; also makes the body position then not matter. Changes in heart rate and oxygen saturation still occur synchronously, however, are less pronounced.

p0037A continuous snoring is characterized by the appearance of continuous snoring signals without or with only a low oxygen desaturation and having irregular variations in heart rate. This suggests the presence of a syndrome with increased resistance of the upper airways through which should be treated in the case of daytime fatigue.

p0038In nocturnal myoclonus with awakening the cyclical changes limited to the heart rate. The snoring and oxygen saturation signals indicate a normal, independent of the heart rate behavior.

p0039If myoclonus occur together with obstructive sleep apnea, also the cyclical snoring and the cyclic oxygen saturation show. However, the slope of the increase in heart rate is greater than with obstructive sleep apnea in myoclonus.

p0040Insomnia manifests itself in a large number of changes in body position, many irregular variations in the heart rate and the incidence of many irregular noises. An oxygen desaturation does not occur here.

p0041The inventive device diagnostics are also given other states possible. For example, patients with dysfunction of the autonomic nervous system, only very small changes in heart rate, even if they are physically active. The same applies to persons with pacemakers. Nevertheless, patients with obstructive sleep apnea show the repeated oxygen saturation and the intermittent snoring.