JP7751998B2 - Patient monitor - Google Patents

Description

The present invention relates to a biological information monitor that receives biological information transmitted wirelessly, such as a central monitor.

Conventionally, central monitors installed in nurse stations at medical institutions have been known as vital sign monitors for monitoring the conditions of multiple patients. Central monitors receive vital sign information (e.g., electrocardiograms, blood pressure, arterial oxygen saturation, etc.) from bedside monitors installed at the bedside of each patient in an intensive care unit, hospital room, etc., and display it on a screen (see, for example, Patent Document 1). Central monitors can also receive and display vital sign information wirelessly transmitted from telemeter transmitters worn by patients.

In order for the central monitor to collect and display wirelessly transmitted vital signs, it goes without saying that the central monitor must be able to correctly demodulate the wirelessly transmitted vital signs.

Generally, wireless communication between bedside monitors and telemetry transmitters (hereinafter referred to as "biometric information acquisition terminals") in a hospital and the central monitor is carried out via antennas installed on the central monitor or in the ceiling of the hallway. Depending on the location of the biometric information acquisition terminal and the wireless propagation environment, the central monitor may not be able to correctly demodulate the biometric information. For example, if the biometric information acquisition terminal is located far from the antenna, or if there is an obstacle between the antenna and the biometric information acquisition terminal that blocks radio waves, or if noise interference occurs, the central monitor may not be able to demodulate the biometric information.

Conventionally, some central monitors have a maintenance function that measures the received field strength from the biometric information acquisition terminal and displays the measurement results. For example, if the received field strength from the biometric information acquisition terminal is lower than a predetermined threshold, this is displayed on the central monitor.

This allows the user of the central monitor to recognize that the biometric information acquisition terminal is not located in an appropriate position to transmit biometric information to the central monitor, i.e., that the biometric information acquisition terminal is located in a location with a poor wireless environment. Using this maintenance function can encourage the user to place the biometric information acquisition terminal in an appropriate wireless environment.

Japanese Patent Application Laid-Open No. 2005-124903

However, radio wave conditions change constantly due to factors such as the location of the biometric information acquisition terminal, malfunctions, antenna deterioration, and external noise. However, the conventional maintenance function described above is performed for short periods of time using available channels that are not monitoring biometric information, and therefore is still insufficient in terms of grasping radio wave conditions.

It is possible to install a spectrum analyzer separate from the central monitor to measure radio wave conditions, but this would complicate the system configuration.

The present invention was made in consideration of the above points, and provides a biological information monitor that can grasp radio wave conditions more accurately than conventional monitors without complicating the system configuration.

One aspect of the biological information monitor of the present invention is
a demodulation unit having a plurality of demodulation circuits for demodulating the plurality of pieces of biometric information wirelessly transmitted from the plurality of biometric information acquisition terminals;
a field strength measuring unit for measuring the field strength of a medical telemetry band including at least all frequency bands demodulated by the demodulation unit;
a storage unit that stores a log of the electric field strength over time obtained by the electric field strength measurement unit;
a display unit that displays the log;
Equipped with.

According to the present invention, the vital sign monitor measures the electric field strength of the medical telemetry band and records and displays a log of the measurement results, allowing the user to understand the past radio wave conditions of the medical telemetry band, including the vital sign monitoring channel. As a result, a vital sign monitor that can accurately grasp the radio wave conditions compared to conventional systems can be realized without complicating the system configuration.

FIG. 1 is a diagram showing a schematic configuration of a biological information monitoring system to which a central monitor according to an embodiment is applied. FIG. 1 is a block diagram showing a configuration of a main part of a central monitor according to an embodiment of the present invention; Block diagram showing the configuration of the receiving unit Figure showing an example of biological information displayed on a central monitor Figure showing an example of the field strength display screen on the central monitor An example of a trend graph of the total field strength of all receiving channels An example of a trend graph of field strength for a specific receiving channel

Embodiments of the present invention will be described in detail below with reference to the drawings.

Figure 1 shows the general configuration of a biological information monitoring system to which the central monitor of this embodiment is applied. The biological information monitoring system 10 in Figure 1 is installed, for example, in a hospital.

A central monitor 100 is installed in the nurse's station, and the central monitor 100 receives each patient's biometric information wirelessly transmitted from biometric information acquisition terminals such as bedside monitors 20 (20-1 to 20-n) or telemeter transmitters 30-1 to 30-m via antennas AN1, AN2-1, AN2-2, and AN2-3.

Antennas AN1, AN2-1, AN2-2, and AN2-3 are attached directly to the central monitor 100 or connected to the central monitor 100 via cables. Specifically, antenna AN1 is attached directly to the central monitor 100, and antennas AN2 (AN2-1 to AN2-3) are connected to the central monitor 100 via cables 400. Antenna AN2 is installed, for example, in the ceiling of a hospital corridor.

The configuration of antenna AN2 may be either an antenna system or a leaky coaxial cable system. The antenna system uses a whip antenna or similar as an antenna, and antennas AN2-1 to AN2-3 are connected by wire. The leaky coaxial cable system uses leaky coaxial cables as antennas AN2-1 to AN2-3. Antennas AN1 and AN2 may be of any system that complies with the specified low-power radio standard. Furthermore, the number of antennas is not limited to the example shown in Figure 1.

In practice, biological information wirelessly transmitted from the bedside monitor 20 and telemeter transmitter 30 (i.e., the biological information acquisition terminal) is first received by antenna AN1 or AN2. In the example of Figure 1, biological information transmitted from telemeter transmitter 30-m is received by antenna AN1, and biological information transmitted from bedside monitors 20-1, 20-n and telemeter transmitter 30-1 is received by wired antenna AN2.

In this way, biological information wirelessly transmitted from medical terminals such as the bedside monitor 20 and telemeter transmitter 30 is received and collected by the central monitor 100 and displayed on the central monitor 100.

Figure 2 is a block diagram showing the main components of the central monitor 100 according to this embodiment.

The central monitor 100 inputs signals received by antennas AN1 and AN2 to the receiver 200. The receiver 200 demodulates the modulated biological information by performing predetermined wireless processing on the input signals. The receiver 200 also has the function of measuring the field strength of radio waves in the medical telemetry frequency band (420 MHz to 450 MHz). The detailed configuration of the receiver 200 will be described later.

Here, we'll briefly explain the frequency bands used in medical telemetry. According to the "Operational Guidelines for Low-Power Medical Telemetry" established by the Japan Electronics and Information Technology Industries Association (JEITA), 420 to 450 MHz is specified as the frequency band used by medical telemetry. Furthermore, six frequency bands (which can also be called bands) 1 to 6 are allocated within the 420 to 450 MHz range. Each of frequency bands 1 to 6 can be assigned 40, 80, or 120 channels (which can also be called "floors" or "biometric information acquisition terminals"). Incidentally, the spacing between each channel is 12.5 kHz.

The biometric information demodulated by the receiving unit 101 is input to the biometric information analysis unit 110. The biometric information analysis unit 110 creates a biometric information waveform from the biometric information and calculates maximum, minimum, and average values, etc.

The output of the biological information analysis unit 110 is input to the display control unit 120 and the alarm control unit 130. The display control unit 120 switches the display based on an operation signal from the operation unit 180. The display control unit 120 displays biological information such as an electrocardiogram, SpO2, and blood pressure on the display unit 140. Furthermore, when the display control unit 120 receives an alarm output instruction signal from the alarm control unit 130, it displays an alarm on the display unit 140. The alarm output instruction signal from the alarm control unit 130 is also input to an alarm indicator 150, which consists of an LED (Light Emitting Diode), a speaker, etc., and the alarm is output as light or sound.

Meanwhile, information on the electric field strength of the radio waves measured by the receiving unit 200 is output to the display control unit 120. Here, the electric field strength information is, for example, information that represents the electric field strength in the form of a two-dimensional graph with frequency on the horizontal axis and power (or voltage) on the vertical axis. This two-dimensional graph is displayed on the display unit 140 by the display control unit 120.

The central monitor 100 also has a control unit 170, an operation unit 180, and a barcode reader 190. The control unit 170 assigns and links carrier frequencies to each biometric information acquisition terminal based on biometric information acquisition terminal identification information input from the operation unit 180 or barcode reader 190, and outputs frequency assignment information to the receiving unit 200.

In addition to this configuration, the central monitor 100 has a memory unit 301. The memory unit 301 records a log of a two-dimensional graph (i.e., a frequency spectrum) with the horizontal axis representing frequency and the vertical axis representing power (or voltage). In other words, the memory unit 301 stores a log of the electric field strength over time. The log stored in the memory unit 301 is displayed on the display unit 140 via the display control unit 120 in response to a user operation.

This makes it possible to display changes in field strength (frequency spectrum) over time. As a result, by specifying a specific date and time of interest, users can find out the field strength of all channels, including the monitoring channel and its adjacent channels, at that date and time, allowing them to accurately grasp the radio wave environment at a particular date and time.

The central monitor 100 of this embodiment also has a trend graph creation unit 302. The trend graph creation unit 302 creates a trend graph by expanding the log of electric field strength over time stored in the memory unit 301 in the time direction. The trend graph created by the trend graph creation unit 302 is displayed on the display unit 140 via the display control unit 120 in response to a user operation.

This allows users to more easily grasp how field strength changes over a desired period of time. As a result, users can accurately grasp, for example, whether interference was occurring on a certain date and time.

Figure 3 is a block diagram showing the configuration of the receiving unit 200.

The receiving unit 200 inputs the signals received by each antenna AN1 and AN2 to the distributor 230 via a bandpass filter (BPF) 210 and an amplifier (AMP) 220.

The distributor 230 outputs the input received signal to the demodulator 240 and the field strength measurement unit 250. Here, the distributor 230 may, for example, select either the signal from antenna AN1 or antenna AN2 and output it to the demodulator 240 and the field strength measurement unit 250, or may combine the signals from antennas AN1 and AN2 and output them to the demodulator 240 and the field strength measurement unit 250.

The distribution of the distributor 230 is controlled, for example, by the user operating the operation unit 180. As a result, for example, if the user wants to know the field strength based on the signal received by antenna AN1, the distributor 230 outputs the signal received by antenna AN1 to the field strength measurement unit 250.

The distributor 230 may also select which received signal from antenna A1 or AN2 to distribute to each of the demodulation circuits 1 to 12 included in the demodulation unit 240. For example, if the telemeter transmitter 30-1 in Figure 1 is assigned to demodulation circuit 1, the signal from telemeter transmitter 30-1 should be stronger at antenna AN2 than at antenna AN1, so the distributor 230 should distribute the received signal from antenna AN2 to demodulation circuit 1.

The demodulation unit 240 has demodulation circuits (which may also be called "receiving modules") equal to the number of beds (which may also be called the "number of channels" or "number of biometric information acquisition terminals"). In the example of Figure 3, it has demodulation circuits 1 to 12 for 12 beds. Specifically, each demodulation circuit 1 to 12 demodulates the biometric information by multiplying the input signal by a different carrier frequency. For example, demodulation circuit 1 multiplies by carrier frequency 1, demodulation circuit 2 multiplies by carrier frequency 2, ... and demodulation circuit 12 multiplies by carrier frequency 12.

The biometric information of each bed (each biometric information acquisition terminal) demodulated by the demodulation unit 240 is converted by the conversion circuit 270 into data suitable for analysis by the biometric information analysis unit 110 (Figure 2).

In addition to this configuration, the receiving unit 200 of the central monitor 100 of this embodiment has a field strength measuring unit 250 in addition to the demodulating unit 240 that demodulates the biological information. The field strength measuring unit 250 measures the field strength of the medical telemetry band, which includes at least all of the demodulation frequency bands demodulated by the demodulating unit 240.

In this embodiment, the field strength measurement unit 250 measures the field strength in the medical telemetry band using a sweep method. Field strength measurement using the sweep method is a known technique, so it will only be briefly described here. The field strength measurement unit 250 converts the input signal to IF (intermediate frequency) using a mixer and local oscillator. At this time, the conversion to IF is performed while automatically sweeping the frequency of the local oscillator, and the power value that has passed through a narrowband IF filter is output as field strength information. Note that the field strength measurement unit 250 may measure field strength information using the FFT method instead of the sweep method.

By measuring and displaying the field strength of radio waves in the medical telemetry band using the field strength measurement unit 250, the user can understand the radio wave environment of the channel to which the biometric information acquisition terminal is assigned.

The operation of distributor 230, demodulator 240, and field strength measurement unit 250 is controlled by wireless control unit 260. For example, wireless control unit 260 controls which of demodulator circuits 1 to 12 to operate based on frequency allocation information from control unit 170. For example, if carrier frequency 1 is assigned to bedside monitor 20-1, carrier frequency 2 is assigned to bedside monitor 20-n, carrier frequency 7 is assigned to telemeter transmitter 30-1, and carrier frequency 9 is assigned to telemeter transmitter 30-m, demodulator circuits 1, 2, 7, and 9 will be operated.

In addition, the wireless control unit 260 assigns a floor (which can also be called a "channel" or "biometric information acquisition terminal") to each demodulation circuit 1-12 by setting carrier frequencies 1-12 for each demodulation circuit 1-12.

Figure 4 shows an example of biological information displayed on the display unit 140 of the central monitor 100. Note that in the example of Figure 4, biological information for eight beds is displayed, but with the configuration of Figure 3 described above, biological information for up to 12 beds can be displayed via wireless reception.

Figure 5 shows an example of a received field strength display image displayed on the display unit 140 of the central monitor 100.

In the example of Figure 5, a field strength measurement selection area AR1, a field strength graph area AR2, a band selection area AR3, an antenna selection area AR4, and a scan start position adjustment area AR5 are displayed. In this embodiment, the display unit 140 has a touch panel configuration, and operation signals corresponding to touch operations by the user are input to the control unit 170, and various controls are changed in response to the operation signals.

The reception strength measurement selection area AR1 displays a "Spectrum analyzer only" button. When the "Spectrum analyzer only" button is touched, the field strength measurement unit 250 measures the field strength. In addition, the reception strength measurement selection area AR1 displays buttons RF-01 to RF-12. These buttons correspond to demodulation circuits 1 to 12; for example, when the RF-01 button is touched, the field strength is measured by demodulation circuit 1, and when the RF-02 button is touched, the field strength is measured by demodulation circuit 2.

In other words, demodulation circuits 1-12 not only have the function of demodulating biological information, but also have the function of measuring the field strength of the medical telemeter band, similar to the field strength measurement unit 250. In other words, because demodulation of biological information requires components similar to the field strength measurement unit 250, such as a mixer and local oscillator, demodulation circuits 1-12 are also able to measure field strength using these components. However, since this embodiment does not demodulate biological information but has a field strength measurement unit 250 dedicated to field strength measurement, it is possible to measure the radio wave conditions in the medical telemeter frequency band regardless of the status of biological information monitoring.

The field strength graph area AR2 displays the field strength of each channel. In the example shown, of the six bands that make up the medical telemetry band (1000s, 2000s, 3000s, 4000s, 5000s, and 6000s), the field strength of the 2000s band is displayed. The user can determine which band's field strength to measure and display by selecting the desired band in the band selection area AR3. In the example shown, the field strength of 120 channels is displayed for each band.

The user can select the antenna for which the field strength will be measured by touching the antenna selection area AR4. For example, touching the "Antenna 1" button will measure and display the field strength of the signal received by antenna AN1, and touching the "Antenna 2" button will measure and display the field strength of the signal received by antenna AN2. Incidentally, instead of selecting just one antenna, it is also possible to select all two or more antennas and measure and display the field strength of their combined received signal.

By touching the scan start position adjustment area AR5, the user can adjust the scan start position where field strength is measured and displayed. Scanning the field strength of all channels within a band can take several tens of seconds, depending on the device's performance. Therefore, if the scan is simply started from the channel with the lowest frequency and the channel of interest is a high-frequency channel, the user will have to wait a long time to find out the field strength around that channel.

The user can avoid this inconvenience by touching the scan start position adjustment area AR5. For example, if the channel of interest is channel 2115, the user touches the "110" button in the scan start position adjustment area AR5. As a result, field strength measurements and display scans are performed starting from channel 2110, allowing the user to quickly find out the field strength around the channel of interest, channel 2115.

Here, the frequency spectrum shown in Figure 5 is a frequency spectrum for a short period corresponding to the scan period by the field strength measurement unit 250. The central monitor 100 of this embodiment stores frequency spectra for multiple periods in the memory unit 301. This allows the user to display the frequency spectrum for a desired period. This allows the user to know the field strength of all channels, including the monitoring channel and its adjacent channels, for the desired period.

Figures 6 and 7 show examples of trend graphs created by the trend graph creation unit 302 and displayed on the display unit 140.

Figure 6 shows an example of a trend graph created and displayed by the trend graph creation unit 302 showing the average field strength of all receiving channels (12 channels in this embodiment). Figure 7 shows an example of a trend graph created and displayed by the trend graph creation unit 302 showing the field strength of a specific channel (e.g., channel 2).

The top row of Figure 6 displays a long-term trend graph, while the bottom row displays a short-term trend graph. The time span of the trend graph displayed in the top row can be set by the user. In the example shown, the user has selected one hour ("1H"), so the time span of the trend graph displayed in the top row is one hour. The user can change the time of the displayed trend graph by operating the arrows in the figure.

Similarly, a long-term trend graph is displayed on the left side of Figure 7, and a short-term trend graph is displayed on the right. The time span of the trend graph displayed on the right can be set by the user. In the example shown, the user has selected one hour ("1H"), so the time span of the trend graph displayed on the right is one hour. The user can change the time of the displayed trend graph by operating the arrows in the figure.

From the trend graph of the average field strength for all receiving channels (12 channels in this embodiment) as shown in Figure 6, the user can infer that the antenna has deteriorated or failed if, for example, the average field strength on a certain date and time is extremely low.

Furthermore, from a trend graph of the electric field strength of a particular channel (e.g., channel 2) such as that shown in Figure 7, if the radio waves from a particular telemeter transmitter become weaker at a certain time, for example, the user can infer that the radio wave propagation environment for that telemeter transmitter has deteriorated (e.g., the transmitter has moved farther away from the antenna).

As described above, according to this embodiment, the central monitor 100 includes a demodulation unit 240 having multiple demodulation circuits (demodulation circuits 1-12) that demodulate multiple pieces of biological information wirelessly transmitted from multiple biological information acquisition terminals (bedside monitor 20, telemeter transmitter 30), a field strength measurement unit 250 that measures the field strength of the medical telemeter band that includes at least all frequency bands demodulated by the demodulation unit 240, a memory unit 301 that stores a log of the field strength over time obtained by the field strength measurement unit 250, and a display unit 140 that displays the log.

This allows the user to understand the past radio wave conditions of channels, including the biological information monitoring channel, and as a result, a biological information monitor 100 can be realized that can accurately understand radio wave conditions compared to conventional systems without complicating the system configuration.

Furthermore, according to this embodiment, an amplifier 220 that amplifies signals from antennas AN1 and AN2 is provided before the demodulation unit 240 and the field strength measurement unit 250, and the demodulation unit 240 and the field strength measurement unit 250 share the same amplifier 220 (in other words, they input signals from the same amplifier 220). This simplifies the configuration of the part that amplifies signals when viewed as the system as a whole by the amount of the shared amplifier, compared to, for example, a system in which the field strength measurement unit is provided outside the central monitor 100 and measures the field strength.

Furthermore, according to this embodiment, a distributor 230 that distributes signals from antennas AN1 and AN2 is provided before the demodulation unit 240 and the field strength measurement unit 250, and the demodulation unit 240 and the field strength measurement unit 250 share the same distributor 230 (in other words, they input signals from the same distributor 220). This simplifies the configuration, as there is no need to provide a separate distributor, as compared to systems in which, for example, the field strength measurement unit is provided outside the central monitor 100 to measure field strength.

Incidentally, in this embodiment, the distribution of the antenna signal by distributor 230 to demodulation unit 240 and the distribution of the antenna signal to field strength measurement unit 250 are the same. For example, if the signal of antenna AN1 is distributed to demodulation unit 240, the signal of antenna AN1 is also distributed to field strength measurement unit 250. This is because it is meaningless unless the signal from the antenna whose field strength is to be measured is the same as the signal from the antenna being demodulated.

The above-described embodiments are merely examples of specific ways of implementing the present invention, and should not be construed as limiting the technical scope of the present invention. In other words, the present invention can be implemented in various forms without departing from its gist or main characteristics.

In the above embodiment, we have described the case where a log of the field strength obtained by the field strength measurement unit 250 is stored, but it is also possible to measure the field strength using the demodulation unit 240 and store a log of that field strength.

In the above embodiment, the present invention has been described as being applied to a central monitor, but it is not limited to this. In essence, it can be widely applied to any biological information monitor that demodulates and displays multiple pieces of biological information wirelessly transmitted from multiple biological information acquisition terminals.

The present invention has the advantage of realizing a biological information monitor that can accurately grasp radio wave conditions compared to conventional systems without complicating the system configuration, making it suitable for central monitors, for example.

10 Biological information monitoring system 20 (20-1 to 20-n) Bedside monitor 30 (30-1 to 30-m) Telemeter transmitter 100 Central monitor 110 Biological information analysis unit 120 Display control unit 130 Alarm control unit 140 Display unit 150 Alarm indicator 170 Control unit 180 Operation unit 190 Barcode reader 200 Receiving unit 210 Bandpass filter (BPF)
220 Amplifier (AMP)
230 distributor 240 demodulation unit 250 field strength measurement unit 260 radio control unit 270 conversion circuit 301 storage unit 302 trend graph creation unit AN1, AN2-1, AN2-2, AN2-3 antennas AR1 field strength measurement selection area AR2 field strength graph area AR3 band selection area AR4 antenna selection area AR5 scan start position adjustment area

Claims (5)

a demodulation unit having a plurality of demodulation circuits for demodulating the plurality of pieces of biometric information wirelessly transmitted from the plurality of biometric information acquisition terminals;
a field strength measuring unit for measuring the field strength of a medical telemetry band including at least all frequency bands demodulated by the demodulation unit;
a storage unit that stores a log of the electric field strength over time obtained by the electric field strength measurement unit;
a display unit that displays the log;
a trend graph creating unit that creates a trend graph of the electric field strength based on the electric field strength over time stored in the storage unit;
A vital sign monitor comprising: an amplifier for amplifying a signal from an antenna is provided before the demodulation unit and the field strength measurement unit;
The demodulation unit and the field strength measurement unit share the same amplifier.
The biological information monitor according to claim 1 . a distributor for distributing a signal from an antenna is provided before the demodulation unit and the field strength measurement unit;
The demodulation unit and the field strength measurement unit share the same distributor.
The biological information monitor according to claim 1 or 2 . A measurement start position in the electric field strength measurement unit can be selected.
The biological information monitor according to any one of claims 1 to 3. The frequency band of the log of the electric field strength over time displayed on the display unit can be selected.
The biological information monitor according to any one of claims 1 to 3.