JP6487081B2 - Biological information monitoring system - Google Patents

Description

  The present invention relates to a biological information monitoring system that monitors biological information of a subject based on a change in the position of the center of gravity of the subject on a bed.

  The biological information of the subject is one of important information for knowing the physical condition of the patient and the cared person in the field of medical care and care. For example, it is possible to grasp the respiratory state of the subject, to grasp symptoms such as sleep apnea syndrome and snoring, and to improve these symptoms.

  It has been proposed to place a load sensor under the leg of the bed and measure the breathing state of the subject based on the measurement value of the load sensor (Patent Document 1). Furthermore, a load detector is arranged under the leg of the bed to determine the movement of the center of gravity of the test organism on the bed, and based on the movement of the center of gravity, the respiratory motion and heartbeat motion of the test organism can be determined. It has been proposed (Patent Document 2).

Japanese Patent No. 4883380 JP-B 61-24010

  In the medical field, it is desired to accurately grasp the position of the center of gravity of the subject on the bed. However, the inventions described in Patent Documents 1 and 2 cannot meet such a request from the field.

  Then, this invention aims at providing the biological information monitoring system which can grasp | ascertain correctly the gravity center position of the test subject on a bed.

According to the first aspect of the present invention,
A biological information monitoring system for monitoring biological information of a subject on a bed,
A plurality of load detectors provided under the bed or under the legs of the bed and for detecting a load by the subject;
A load separation unit that separates a load component that vibrates according to the heartbeat of the subject from the load by the subject;
A center-of-gravity position calculation unit for obtaining a position of the center of gravity of the subject based on a load component that vibrates according to the heartbeat of the subject,
The load separation unit, based on a frequency spectrum of a temporal variation in load by the subject detected by at least one of the plurality of load detectors when there are a plurality of subjects on the bed. The load by is separated into the load by each of the plurality of subjects, and the load component that vibrates according to the heartbeat of each subject is separated from the load by each of the plurality of subjects,
The center-of-gravity position calculation unit is provided with a biological information monitoring system that obtains the position of the center of gravity of each subject based on a load component that vibrates according to the heartbeat of each subject.

According to the second aspect of the present invention,
A biological information monitoring system for monitoring biological information of a subject on a bed,
A plurality of load detectors provided under the bed or under the legs of the bed and for detecting a load by the subject;
A load separation unit that separates a load component that vibrates according to the heartbeat of the subject from the load by the subject;
A center-of-gravity position calculation unit for obtaining a position of the center of gravity of the subject based on a load component that vibrates according to the heartbeat of the subject,
The load separation unit further separates a load component that vibrates according to the breathing of the subject from the load by the subject,
The center-of-gravity position calculation unit is further provided with a biological information monitoring system that obtains the position of the subject's breathing center of gravity based on a load component that vibrates according to the subject's breathing.

In the biological information monitoring system according to the second aspect, when the load separating unit includes a plurality of subjects on the bed, the load time by the subject detected by at least one of the plurality of load detectors. A load component that vibrates according to a heartbeat of each subject from the load by each of the plurality of subjects, and the load by each of the plurality of subjects may be separated based on a frequency spectrum of the dynamic variation, and The components that vibrate according to the breathing of each subject may be separated,
The center-of-gravity position calculation unit may obtain the position of the heart-center of gravity of each subject based on a load component that vibrates according to the heart rate of each subject, and each based on the load component that vibrates according to the breath of each subject. The position of the subject's respiratory center of gravity may be obtained.

  According to the biological information monitoring system of the present invention, it is possible to accurately grasp the position of the center of gravity of the subject on the bed.

FIG. 1 is a block diagram showing a configuration of a biological information monitoring system according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing the arrangement of the load detector with respect to the bed. FIG. 3 is a flowchart showing the center-of-gravity locus calculation method according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing the arrangement of four load detection areas defined on the upper surface of the bed. FIG. 5 shows an example of a load signal from the load detector. FIG. 6 shows an example of the subject's center of gravity locus. FIG. 7 is a flowchart showing a method of calculating the position of the center of gravity of the subject based on the respiratory component or the heartbeat component separated from each load signal. FIG. 8 is a block diagram illustrating an overall configuration of a bed system according to a modification.

<First Embodiment>
A first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the biological information monitoring system (respiration waveform drawing system, respiratory information acquisition system) 100 according to the present embodiment performs observation and measurement in order to grasp the biological state of the subject on the bed, and detects the load. Unit 1, control unit 3, storage unit 4, and display unit 5 are mainly included. The load detection unit 1 and the control unit 3 are connected via an A / D conversion unit 2. Further, a notification unit 6 and an input unit 7 are connected to the control unit 3.

  The load detection unit 1 includes four load detectors 11, 12, 13, and 14. Each of the load detectors 11, 12, 13, and 14 is a load detector that detects a load using, for example, a beam-type load cell. Such a load detector is described in, for example, Japanese Patent No. 4829020 and Japanese Patent No. 4002905. Each of the load detectors 11, 12, 13, and 14 is connected to the A / D converter 2 by wiring.

The four load detectors 11, 12, 13, and 14 of the load detection unit 1 are arranged under the legs of the bed used by the subject. Specifically, as shown in FIG. 2, the load detectors 11, 12, 13, and 14 are below casters C ₁ , C ₂ , C ₃ , and C ₄ attached to the lower ends of the legs at the four corners of the bed BD. Each is arranged.

  The A / D converter 2 includes an A / D converter that converts an analog signal from the load detector 1 into a digital signal, and is connected to the load detector 1 and the controller 3 by wiring.

  The control unit 3 is a dedicated or general-purpose computer, and includes a frequency analysis unit 31, a signal separation unit (load separation unit) 32, a gravity center position calculation unit 33, and a biological information analysis unit (bed presence determination unit) 34. ing.

  The storage unit 4 is a storage device that stores data used in the biological information monitoring system 100. For example, a hard disk (magnetic disk) can be used. The display unit 5 is a monitor such as a liquid crystal monitor that displays information output from the control unit 3 to a user of the biological information monitoring system 100.

  The notification unit 6 includes a device that performs predetermined notification visually or audibly based on information from the control unit 3, for example, a speaker. The input unit 7 is an interface for performing a predetermined input to the control unit 3 and can be a keyboard and a mouse.

  Using such a biological information monitoring system 100, it is possible to detect and monitor various biological information including the respiratory state of the subject on the bed. Acquisition and monitoring of various types of biological information are performed based on changes in the position of the center of gravity of the subject on the bed.

  An operation for calculating the position of the center of gravity of the subject on the bed using the biological information monitoring system 100 will be described. As shown in FIG. 3, the calculation of the center of gravity position of the subject using the biological information monitoring system 100 includes a load detection step (S01) for detecting the load of the subject, and temporal variation of the center of gravity position of the subject based on the detected load. And a gravity center locus calculation step (S02) for calculating (center of gravity locus).

In the load detection step S01, the load of the subject S on the bed BD is detected using the load detectors 11, 12, 13, and 14. Since the load detectors 11, 12, 13, and 14 are respectively disposed below the casters C ₁ , C ₂ , C ₃ , and C ₄ as described above, loads applied to the upper surface of the bed BD are four loads. The detectors 11, 12, 13, and 14 are dispersed and detected. Specifically, as shown in FIG. 4, the rectangular upper surface of the bed BD is divided into two vertically and horizontally, and is equally divided into four rectangular regions I to IV.

  As a result, the load applied to the region I where the lower left half of the subject S lying on the bed BD (sleeping on his back) is mainly detected by the load detector 11, and the lower right half of the subject S in the same state is detected. The load applied to the region II where the is located is mainly detected by the load detector 12. Similarly, the load applied to the region III where the upper right half of the subject S lying on the bed BD is located is mainly detected by the load detector 13, and the region IV where the upper left half of the subject S in the same state is located. The load applied to is mainly detected by the load detector 14. When the subject S is not on the bed BD, the total output from the load detectors 11, 12, 13, and 14 represents the weight of the bed alone, and when the subject S is on the bed BD, the load Since the total output from the detectors 11, 12, 13, and 14 represents the weight of the bed alone and the weight of the subject S, the subject S can store the weight of the bed alone in the storage unit 4 in advance. The weight of the subject S can be measured when he is in bed. If the weight of the bed is not uniform in the four areas, the difference is stored as the bed weight corresponding to the load detector. In addition, it is desirable to reflect in the bed weight a situation that causes a weight other than the subject S during the actual measurement, for example, that a futon or luggage is placed.

  Each of the load detectors 11, 12, 13, and 14 detects a load (load change) and outputs it as an analog signal to the A / D conversion unit 2. The A / D converter 2 converts the analog signal into a digital signal (hereinafter referred to as “load signal”) with a sampling period of 5 milliseconds, for example, and does not go through the frequency analyzer 31 or the signal separator 32. And output to the gravity center position calculation unit 33.

An example of the load signal is shown in FIG. FIG. 5 shows load signals s ₁ (solid line), s ₂ (dashed line), and s ₃ (dashed line) output from the load detectors 11, 12, 13, and 14 output from time t ₁₀ to time t _14. , S ₄ (two-dot chain line). Subject S is between from time _{t 10} ~ time _{t 11} (time _{P 11)} have been supine in central as bed BD shown in FIG. 4, between times _{t 11} ~ time _{t 12} ( During the period P ₁₂ ), the bed BD is moved to the areas I and IV of the bed BD, and during the period from the time t ₁₂ to the time t ₁₃ (period P ₁₃ ), is slightly closer to the center of the bed BD than the period P _12. It has been observed that during the period from time t ₁₃ to time t ₁₄ (period P ₁₄ ), the person was lying on the center of the bed BD.

In the period P ₁₁ , the subject S is lying on the center of the bed BD as shown in FIG. 4. Therefore, in this period P ₁₁ , signals from the load detectors 13 and 14 arranged on the head side of the subject S are displayed. s ₃ and s ₄ are substantially equal, and signals s ₁ and s ₂ from the load detectors 11 and 12 arranged on the leg side of the subject S are substantially equal.

The period _{P 12,} the subject S region of the bed BD I, because it was moved to the IV side, in this period _{P 12,} region I, the signal _s 1 from the load detector 11 and 14 arranged in IV, s ₄ indicates a large load value compared to the period P ₁₁ , and signals s ₂ and s ₃ from the load detectors 12 and 13 arranged in the regions II and III indicate a small load value compared to the period P _11. Yes.

The period _{P 13,} the subject S, so was slightly moves to the center side of the bed BD as compared to the period _{P 12,} in this period _{P 13,} region I, the load detector 11 and 14 arranged in IV The signals s ₁ and s ₄ of FIG. ₄ indicate smaller load values than the period P ₁₂ , and the signals s ₂ and s ₃ from the load detectors 12 and 13 arranged in the regions II and III are larger than the period P _12. The load value is shown.

The period _{P 14,} the subject S, so was supine in central same bed BD to the period _{P 11,} the signal _s 1 ~s ₄ during this period _{P 14,} the signals _s 1 ~s ₄ during the period _{P 11} Is the same.

In the gravity center locus calculation step S02, the gravity center position calculation unit 33 determines the position G (X, Y) of the gravity center G of the subject S on the bed BD based on the load signals s _{1 to} s ₄ from the load detectors 11 to 14. Calculation is performed at a predetermined period T (for example, equal to the above sampling period of 5 milliseconds), and a temporal variation (center of gravity locus GT) of the position of the center of gravity G of the subject S is obtained. Here, (X, Y) indicates coordinates on the XY coordinate plane, where X is taken in the longitudinal direction and Y is taken in the lateral direction with the center of the bed BD as the origin (FIG. 6).

The calculation of the position G (X, Y) of the center of gravity G by the center of gravity position calculation unit 31 is performed by the following calculation. In other words, G (X, Y) represents the coordinates of the load detectors 11, 12, 13, 14 as (X ₁₁ , Y ₁₁ ), (X ₁₂ , Y ₁₂ ), (X ₁₃ , Y ₁₃ ), (X ₁₄ ), respectively. , Y ₁₄ ), and the detected load values of the load detectors ₁₁ , ₁₂ , ₁₃ , and ₁₄ are respectively calculated as W ₁₁ , W ₁₂ , W ₁₃ , and W _{14 according} to the following equations.

  The center-of-gravity position calculation unit 33 calculates the time G of the position G (X, Y) of the center of gravity G while calculating the position G (X, Y) of the center of gravity G with a predetermined sampling period T based on the above formulas 1 and 2. Change, that is, the center-of-gravity locus GT is obtained and stored in the storage unit 4, for example.

An example of the center of gravity locus GT calculated by the center of gravity position calculating unit 33 is shown in FIG. 6 shows the position G (X _P11 , Y _P11 ) of the center of gravity G of the subject S on the bed BD at any time t ₁₁₀ , t ₁₂₀ , t ₁₃₀ within the periods P ₁₁ , P ₁₂ , P _{13 of} FIG. , G (X _P12 , Y _P12 ), G (X _P13 , Y _P13 ), and the dot-and-dash line arrows connecting them represent positions G (X _P11 , Y _P11 ) to G (X _P13 , Y _P13 ). The center-of-gravity locus GT of the center-of-gravity G of the subject S moving up to is shown.

  In the present embodiment, the biological information analysis unit 34 analyzes the presence / absence of the body movement of the subject S and the state thereof based on the center of gravity locus GT of the subject S calculated by the gravity center position calculation unit 33 as described above. Specifically, the biological information analysis unit 34 calculates the moving speed (movement amount per unit time) of the center of gravity G based on the change in the position of the center of gravity G of the subject S at each time stored in the storage unit 4. If the calculated speed exceeds a predetermined threshold value, it is determined that the subject S is moving. The body movement of the subject S includes body movement (large body movement) caused by a relatively large body movement accompanied by movement of the torso of the subject S, such as turning over, movement of the limbs and face, etc. It includes body movements (small body movements) caused by relatively small body movements that do not involve movement of the torso.

Here, in the center-of-gravity locus calculation step S02, as shown in Equations 1 and 2, the total loads W ₁₁ , W ₁₂ , W ₁₃ , and W ₁₄ detected by the load detectors ₁₁ , ₁₂ , ₁₃ , and ₁₄ are calculated. Based on this, the gravity center position G (X, Y) is calculated. For this reason, for example, when any object is placed at a position away from the subject S on the bed, the center-of-gravity position G (X, Y) calculated by the above Equations 1 and 2 is placed on the bed. Due to the influence of the load on the object, the actual center of gravity of the subject S may deviate. Therefore, in the present embodiment, components included in a specific frequency band are separated from each of the load signals s _{1 to} s ₄ output from the load detectors 11 to 14, and the center of gravity position of the subject S based on the separated components is also determined. Calculated.

Hereinafter, a process of separating a component included in a respiration frequency band (about 0.2 Hz to about 0.33 Hz) from each of the load signals s _{1 to} s ₄ and calculating the position of the center of gravity of the subject S based on the separated components. Will be described with reference to the flowchart of FIG.

In the frequency analysis step S10, the frequency analysis unit 31 obtains a frequency spectrum by Fourier transform for each or at least one of the load signals s _{1 to} s ₄ output from the load detectors 11 to 14.

In the signal separation step S20, the signal separation unit 32 specifies the peak frequency (that is, the respiration frequency of the subject S) included in the respiration frequency band from the frequency spectrum obtained in the frequency analysis step S10. Then, the signal separation unit 32 separates components s _b1 to s _b4 (hereinafter referred to as “respiration components”) corresponding to the specified peak frequency from each of the load signals s _{1 to} s ₄ .

In the center-of-gravity position calculation step S30, the center-of-gravity position calculation unit 31 calculates the center-of-gravity position G _b of the subject S on the bed based on the respiratory components s _{b1 to} s _b4 separated in the signal separation step S20 according to the above formulas 1 and 2. (X, Y) is calculated.

In the biological information analysis step S40, the biological information analysis unit 34 calculates the center-of-gravity position G (X, Y) calculated based on the total load and the center-of-gravity position G _b (X, Y) calculated based on the respiratory components s _{b1 to} s _b4 . Any of (Y) may be adopted. For example, after comparing the center of gravity position G (X, Y) calculated based on the total load and the center of gravity position G _b (X, Y) calculated based on the respiratory components s _{b1 to} s _b4 , Which one is adopted as the center of gravity position may be determined. Alternatively, when the distance between the gravity center position G (X, Y) based on the total load and the gravity center position G _b (X, Y) based on the respiratory component is calculated and the distance exceeds a predetermined range, The information analysis unit 34 may adopt the gravity center position G _b (X, Y) based on the respiratory component as the gravity center position of the subject S. Here, the predetermined range may be set as appropriate in consideration of, for example, the size of the bed, the height, weight, etc. of the subject S.

  The biological information analysis unit 34 analyzes various biological information of the subject S using the adopted center-of-gravity position.

  By the way, human respiration is performed by moving the thorax and the diaphragm to expand and contract the lungs. Here, when inhaling, that is, when the lungs expand, the diaphragm descends downward, and the internal organs also move downward. On the other hand, when exhaling, that is, when the lungs contract, the diaphragm rises upward and the internal organs also move upward. The inventor of the present invention has found through research that the center of gravity G vibrates substantially along the extending direction (body axis direction) of the spine (hereinafter referred to as “breathing vibration”). ).

  Therefore, when the position of the center of gravity is breathing and vibrating in a specific direction, the biological information analyzing unit 34 regards the specific direction as the direction of the body axis of the subject S, and the posture of the subject S on the bed (the body axis is the bed Whether it is parallel or inclined with respect to the longitudinal direction. The direction of the respiratory vibration can be specified by, for example, specifying an extreme point and an extreme point appearing immediately before or after the extreme point from the trajectory of the respiratory vibration and obtaining an axis connecting the two extreme points.

  In addition, the biological information analysis unit 34 plots the distance between the position of the center of gravity projected at each time on the body axis and the vibration center of the respiratory vibration, with the direction of the body axis as the vertical axis and the time axis as the horizontal axis. Thus, the respiratory waveform of the subject S is drawn. Then, the biological information analysis unit 34 determines the respiratory rate of the subject S by counting the number of local maximum values or local minimum values that appear on the respiratory waveform. Further, based on the amplitude of the barycentric position (that is, the amplitude of the respiratory vibration or the amplitude of the respiratory waveform), the ventilation volume (breathing depth) in one breath of the subject S is calculated.

Next, components included in the frequency band of the heartbeat (about 0.5 Hz to about 3.3 Hz, hereinafter referred to as “heartbeat band”) are separated from each of the load signals s _{1 to} s ₄ , and based on the separated components The process of calculating the gravity center position of the subject S will be described with reference to the flowchart of FIG. Note that this process may be executed in parallel with the calculation of the center-of-gravity position G _b (X, Y) based on the respiratory component, or may be executed alone.

In the frequency analysis step S10, the frequency analysis unit 31 obtains a frequency spectrum of the heart rate band by Fourier transform for each or at least one of the load signals s _{1 to} s ₄ output from the load detectors 11 to 14.

In the signal separation step S20, the signal separation unit 32 specifies the peak frequency (that is, the heartbeat frequency of the subject S) included in the heartbeat band from the frequency spectrum obtained in the frequency analysis step S10. Then, the signal separation unit 32 separates components s _h1 to s _h4 (hereinafter referred to as “heartbeat components”) corresponding to the specified peak frequency from each of the load signals s _{1 to} s ₄ .

In the center of gravity position calculating step S30, the center of gravity position calculating unit 31 on the basis of the heartbeat component _s h1 _{~s h4} separated by the signal separation step S20, Equation 1 above, the center of gravity G (hereinafter the subject S on the bed by Equation 2 , Called “centroid G _h based on heart rate component”).

The center of gravity _{G h} based on the heartbeat component of the subject S on the bed which is calculated using the heartbeat component _s h1 _{~s h4} separated from the load signal _s 1 ~s ₄ has the following characteristics.

(1) Since the center of gravity G _h based on the heart rate component is calculated using only the heart rate components s _{h1 to} sh ₄ that vibrate according to the heart rate of the subject S among the load signals s _{1 to} s ₄ . The subject does not move when a load from a third person (such as a visitor) who has a heartbeat of a frequency different from that of the subject S or a load from an inanimate object (such as a bag) that does not have a heartbeat is applied to the bed BD. Move only when S moves.

(2) The inventors of the present invention, observation of the trajectory of the movement of the center of gravity G _h based on the heartbeat component, the direction the center of gravity G _h based on the heartbeat component, which has a certain degree rotating body axis of the subject S counterclockwise Was found to be slightly oscillating along. This vibration (hereinafter referred to as “heartbeat vibration”) is considered to be caused by the heartbeat.

In the biological information analysis step S40, the biological information analysis unit 34 compares the center of gravity position G (X, Y) calculated based on the total load with the position of the center of gravity G _h based on the heart rate component, and the center of gravity position of the subject S You may decide which one to use. This determination can be made in the same manner as described above with respect to the gravity center position G _b (X, Y) based on the respiratory component.

The biological information analysis unit 34 can also determine whether or not the subject S is present on the bed BD, that is, whether he / she is present, based on whether or not the center of gravity G _h based on the heart rate component is obtained. . When the subject S does not exist on the bed BD, each of the signal components s _{1 to} s ₄ of the load detectors 11 to 14 has no component that varies depending on the heart rate of the subject S. The components cannot be separated, and the center of gravity G _h based on the heart rate component cannot be calculated. Therefore, the presence determination can be performed based on the presence / absence of the heart rate component and the possibility of calculating the center of gravity G _h based on the heart rate component. For example, the biological information analysis unit 34 may determine that the subject S is present when it is confirmed that the center of gravity G _h based on the calculated heart rate component is present on the bed BD. In addition, when it is confirmed that the center of gravity G _h based on the heartbeat component is oscillating in a predetermined direction inclined with respect to the body axis of the subject S, it may be determined that the subject S is present.

Biometric information analysis unit 34 further includes a vibration direction of the center of gravity G _h based on the heartbeat component, can also be determined, the direction of the body axis of the subject S, the heart rate from the vibration per minute of the center of gravity G _h based on heartbeat component Can also be requested.

  The effects of the biological information monitoring system 100 of this embodiment are summarized below.

The signal separation unit 32 according to the present embodiment is included in, for example, a respiratory component included in a respiratory frequency band or a heartbeat frequency band from each of the load signals s _{1 to} s ₄ output from the load detectors 11 to 14. Separate heart rate components. The center-of-gravity position calculation unit 33 according to the present embodiment uses not only the center-of-gravity position G (X, Y) calculated based on the total load, but also the center-of-gravity position G _b (X, Y) based on the respiratory component and the heart rate component. Based on the center of gravity position G _h (X, Y) is calculated. For this reason, the biological information analysis unit 34 analyzes various biological information of the subject S using the gravity center position G _b (X, Y) based on the respiratory component and the gravity center position G _h (X, Y) based on the heartbeat component. Can be utilized for. The center-of-gravity position G _b (X, Y) based on the respiratory component and the center-of-gravity position G _h (X, Y) based on the heart rate component are subjected to a load that does not originate from the subject S, such as luggage or visitors, on the bed BD. If these are used, the biological information of the subject S can be analyzed more accurately.

For example, the biological information analysis unit 34 uses the center-of-gravity position G _b (X, Y) based on the respiratory component, such as the posture (body axis direction) of the subject S on the bed, the respiratory waveform, the respiratory rate, and the respiratory ventilation. Respiratory condition can be analyzed.

In addition, the biological information analysis unit 34 can determine whether the subject S is present based on the heart rate component and the presence or absence of the center of gravity G _h based on the heart rate component. Since heartbeat cannot be stopped consciously unlike breathing, the presence / absence of subject S can be more reliably determined by making a presence determination based on the presence of the heart rate component and the center of gravity G _h based on the heart rate component. I can judge.

  The biological information monitoring system 100 according to the present embodiment obtains the biological information of the subject S using the load detectors 11 to 14 disposed below the legs of the bed BD. Therefore, it is not necessary to attach a measuring device to the body of the subject S, and the subject S does not feel uncomfortable or uncomfortable.

<Modification>
In the biological information monitoring system 100 according to the above embodiment, the following modification may be employed.

  For example, the respiratory cycle varies depending on the gender, physique, vital capacity, etc. of the subject S, and there are individual differences in the cardiac cycle. Therefore, when there are a plurality of subjects S on the bed BD, different peak frequencies appear as many as the number of subjects S in the frequency band of respiration and / or heartbeat in the frequency spectrum obtained in the frequency analysis step S10.

Therefore, when a plurality of peak frequencies appear in the frequency band of respiration and / or heartbeat, the signal separation unit 32 determines that there are a plurality of subjects S on the bed, and each of the load signals s _{1 to} s ₄ . From the above, the respiratory component and / or the heartbeat component corresponding to each subject S may be separated. Then, the center-of-gravity position calculation unit 33 may calculate the center-of-gravity position of each subject S based on the respiratory component and / or the heartbeat component corresponding to each subject S. For example, when peaks appear in the frequency ν1 and the frequency ν2 in the frequency band of respiration, the signal separation unit 32 determines that there are two subjects S on the bed, and the load signal s ₁ in the signal separation step S20. from each ~s _4, the respiratory component corresponding to the frequency .nu.1, separating the respiratory component corresponding to the frequency .nu.2. The center-of-gravity position calculating unit 33 then calculates the center-of-gravity position G _b1 (X, Y) based on the respiratory component corresponding to the peak frequency ν ₁ and the center of gravity based on the respiratory component corresponding to the peak frequency ν ₂ in the center-of-gravity position calculating step S30. The position G _b2 (X, Y) is calculated.

According to the above modification, even when there are a plurality of subjects S on the bed, the center of gravity G _b based on the respiration of each subject S and the center of gravity G _h based on the heartbeat can be obtained individually. It is possible to accurately grasp the position of the center of gravity of S.

In the biological information monitoring system 100 of the above embodiment, the biological information analysis unit 34 has obtained a load applied to the bed BD that has increased by a predetermined value (for example, about 40 kg) or more and the center of gravity G _h based on the heart rate component or heart rate. The subject S may determine that the subject S has landed, and the subject S has left the floor when the load applied to the bed BD is reduced by a predetermined value or more and the heart rate component or the center of gravity G _h based on the heart rate cannot be obtained. You may judge.

When there is an element (impact element) that strikes the bed BD at a predetermined cycle on the bed BD, the load signals s _{1 to} s ₄ from the load detectors 11 to 14 are the same at the predetermined cycle. A phase waveform appears. If the load component including the waveform is separated using the frequency analysis unit 31 and the signal separation unit 32, and the center of gravity position is calculated by the center of gravity position calculation unit 33 using this, the center of gravity position of the impact element can be calculated. .

  In the above embodiment, the load detectors 11, 12, 13, and 14 are not limited to load sensors using a beam-type load cell, and for example, force sensors may be used.

  In the above embodiment, the number of load detectors is not limited to four. Five or more load detectors may be used with additional legs on the bed BD. Or you may arrange | position a load detector only to three of the legs of bed BD. Even when there are three load detectors, if they are not arranged in a straight line, the center-of-gravity position G of the subject S on the bed BD surface can be detected.

In the above embodiment, the load detectors 11, 12, 13, and 14 are respectively disposed under the casters C ₁ , C ₂ , C ₃ , and C ₄ attached to the lower ends of the legs of the bed BD. This is not a limitation. Each of the load detectors 11, 12, 13, and 14 may be provided between the four legs of the bed BD and the floor plate of the bed BD, or the four legs of the bed BD can be divided vertically. For example, it may be provided between the upper leg and the lower leg. Further, the load detectors 11, 12, 13, and 14 may be integrated with the bed BD to constitute a bed system BDS including the bed BD and the biological information monitoring system 100 of the present embodiment (FIG. 8). In the present specification, “the load detector provided on the bed” means a load detector provided between the four legs of the bed BD and the floor plate of the bed BD as described above, an upper leg, It means a load detector provided between the lower leg.

  In the above embodiment, a signal amplification unit that amplifies the load signal from the load detection unit 1 or a filtering unit that removes noise from the load signal may be provided between the load detection unit 1 and the A / D conversion unit 2. good.

  In the biological information monitoring system 100 of the above embodiment, the display unit 5 is not limited to displaying information on the monitor so that the user can visually recognize it. For example, the display unit 5 may be a printer that periodically prints and outputs the breathing state (respiration rate, respiratory ventilation), heartbeat state, and physical condition of the subject S, or lights up a blue lamp when the person is in bed, leaves the bed If it is inside, it may be displayed using a simple visual expression such as lighting of a red lamp. Alternatively, the display unit 5 may convey the biological information of the subject S to the user by voice. Furthermore, the biological information monitoring system 100 may not have the display unit 5 and may only have an output terminal for outputting information. A monitor (display device) or the like for performing display is connected to the biological information monitoring system 100 via the output terminal.

  The notification unit 6 of the embodiment described above is audibly informing, but the notification unit 6 may be configured to visually notify by flashing light or the like, and is configured to notify by vibration. Also good. Moreover, the biological information monitoring system 100 according to the above embodiment may not have the notification unit 6.

  As long as the characteristics of the present invention are maintained, the present invention is not limited to the above embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

  According to the biological information monitoring system of the present invention, since the center of gravity of the subject can be obtained more accurately, data suitable for observation is mainly provided by a user who is a doctor, contributing to improvement in medical quality. can do.

DESCRIPTION OF SYMBOLS 1 Load detection part 11, 12, 13, 14 Load detector 2 A / D conversion part 3 Control part 31 Frequency analysis part 32 Signal separation part 33 Gravity center position calculation part 34 Biological information analysis part 4 Storage part 5 Display part 6 Notification part 7 Input unit 100 Biological information monitoring system BD Bed BDS Bed system GT Center of gravity locus S Subject

Claims (3)

A biological information monitoring system for monitoring biological information of a subject on a bed,
A plurality of load detectors provided under the bed or under the legs of the bed and for detecting a load by the subject;
A load separation unit that separates a load component that vibrates according to the heartbeat of the subject from the load by the subject;
A center-of-gravity position calculation unit for obtaining a position of the center of gravity of the subject based on a load component that vibrates according to the heartbeat of the subject,
The load separation unit, based on a frequency spectrum of a temporal variation in load by the subject detected by at least one of the plurality of load detectors when there are a plurality of subjects on the bed. The load by is separated into the load by each of the plurality of subjects, and the load component that vibrates according to the heartbeat of each subject is separated from the load by each of the plurality of subjects,
The center-of-gravity position calculation unit is a biological information monitoring system that determines the position of the center of gravity of each subject based on a load component that vibrates according to the heartbeat of each subject. A biological information monitoring system for monitoring biological information of a subject on a bed,
A plurality of load detectors provided under the bed or under the legs of the bed and for detecting a load by the subject;
A load separation unit that separates a load component that vibrates according to the heartbeat of the subject from the load by the subject;
A center-of-gravity position calculation unit for obtaining a position of the center of gravity of the subject based on a load component that vibrates according to the heartbeat of the subject,
The load separation unit further separates a load component that vibrates according to the breathing of the subject from the load by the subject,
The center-of-gravity position calculation unit is a biological information monitoring system that further obtains the position of the subject's breathing center of gravity based on a load component that vibrates according to the subject's breathing. The load separation unit, based on a frequency spectrum of a temporal variation in load by the subject detected by at least one of the plurality of load detectors when there are a plurality of subjects on the bed. Separating the load due to each of the plurality of subjects, separating the load component that vibrates according to the heartbeat of each subject and the component that vibrates according to the breath of each subject from the load due to each of the plurality of subjects,
The center-of-gravity position calculation unit obtains the position of the heart-center of gravity of each subject based on the load component that vibrates according to the heartbeat of each subject, and breaths of each subject based on the load component that vibrates according to the breathing of each subject The biological information monitoring system according to claim 2, wherein the position of the center of gravity is obtained.

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