ES2276616A1 - Patient monitoring system - Google Patents

Abstract

The invention relates to a patient monitoring system which uses wireless connections and which, for each patient, includes devices for taking biomedical data, such as an electrocardiogram (3), a pulsoximeter (4), a blood pressure measuring device (5) and a breathing indicator (6), all of said components forming a wireless personal area network (7) which groups said devices with a LR-WPAN gateway (9). According to the invention, a gateway (10) between the different LR-WPAN networks is used to provide and display data and information relating to the monitoring that has been performed and to transmit appropriate messages to the different display devices which are connected to the hospital monitoring services or system.

Description

Patient monitoring system.

Field of the Invention

The present invention develops a system for the monitoring of biomedical data of patients who are evaluated by devices grouped in wireless network of personal area. Specifically groups electrocardiogram data, pulsi-oximetry, blood pressure and indicator breathing. The system manages said biomedical data of each real-time patient, linking with different systems and information services, so that it performs the controls that are  parameterize and timely notices according to them, transmitting relevant information to different types of media or display, management and interaction with the system.

Background

Modern hospitals and care and care that medical centers are required today the use of different means of monitoring the patients In particular, electro sockets are common cardiogram, pulsi-oximetry and measurement of blood pressure that are traditionally checked visually regularly on different monitors by staff doctor.

The centralization and organization of any of these devices for the different patients, of way that the most significant variations in them produce adequate signals that medical personnel can control in charge of that room. Also known are systems of integration of some biometric data collection devices in an adequate computer network for its control.

European patent EP 1433432 of Brainlab AG, develops a system that integrates several devices of medical use, in which a central control unit performed with a processor receives the signals from the different devices and encodes those signals to a unified format, while another processor performs the coding of said signals to be used by the different components that control the relevant medical instruments.

However, said system does not provide a suitable means for monitoring biomedical data of a plurality of patients located in one or different rooms, nor allows setting up a medium that allows such monitoring when these patients are transferred, nor does it allow integrate decentralized and distant monitoring within the same system of said patients.

On the other hand, the means of establish the monitoring of some type of biomedical data and integrate it into a wireless network, including connecting that network to internet and allow the evaluation of remotely located patients but connected to that network.

For example, US2002 / 0013517 provides a patient monitoring system that through a wireless network obtains biomedical data from patients who they have a wireless signal transmitter attached to the socket of control of a personal biological level. Patients can be displaced by the hospital and different network access points  wireless, according to the already known specifications of the wireless networks, will capture the signals from their transmitters data. The patent establishes a system for the beginning and end of communications between the different points that make up the network.

It persists however without solving the question of  establish a patient monitoring system that integrates a particular biomedical data set and integrate them into a general system. Specifically, the need to establish persists a system that configures a personal set of biomedical data, captured in real time by the appropriate sensors, and that these personal area networks with said biomedical data sets participate in a system that integrates other analogues from others patients and form a global patient monitoring system with said set of data of each individual.

In general, it can be said that it is vital importance not only obtaining a biometric data of a special type, but obtaining a set of such data Referrals to each patient. The pulse oximetry, by example, it could provide an erroneous indication about the breathing of the patient, but the breathing indicator of the This invention allows complementing said information and Know if the patient breathes properly. Thus, it is not only useful have for each patient the quatern of biomedical data proposed by the invention, but said data set is complementary in its interpretation.

That is why one of the main objects of the present invention is to solve one of the problems raised regarding the monitoring of patients in operating rooms and hospitals, especially those derived from the mobilization of patients both in the pre-operative phases, surgery, as in the post-operative, providing monitoring for the quatern of data characteristic of the present invention

Another objective and advantages obtained with the system of the present invention refers to the increase of the quality and comfort of hospital stays of patients, being another of the main reasons for this invention extend the coverage of the monitoring of patients from hospital facilities to other locations such as nursing homes, private homes, outpatients, etc.

Brief Explanation of the Invention

The patient monitoring system consists of of several differentiated elements that provide flexibility to system:

- data capture subsystems Biometric (ECG, Blood Pressure, Pulsi-oximetry and breathing indicator);

- integration interfaces between the different signal capture sub-systems and elements that configure personal area networks

- area network coordinator module personal

- interface module between the different networks of personal areas and other networks based on protocols such as Ethernet or Bluetooth

- coding of electrocardiograms (ECG) by waveform coding techniques

- channel quality indicators, detection of power and battery levels of the devices.

The invention uses wireless connections between its parts, for example by means of the IEEE 802.15.4-2003 standard that defines the protocol of communication and interconnection of devices via radio-frequency in personal area networks (WPAN - wireless personal area network). The standard uses CSMA-CA (Carrier Sense Multiple Acces with Collision Avoidance - avoids collisions) as does the IEEE 802.3 standard that defines Ethernet. IEEE 802.15.4-2003 supports both star topologies and point to
point.

The selected protocol is highly indicated for the implementation of this monitoring system due to the low variability, from the statistical point of view, of the different bio-signals that are monitored, supporting transmission rates over 250 Kbps radio channels, 40 Kbps and 20 Kbps, depending on the carriers / channels available within the ISM II band that are configured within the range 868/915 Mhz and 2,450 Ghz.

The protocol used, IEEE 802.15.4-2003, allows easy installation and system configuration by healthcare personnel, providing 10 m coverage areas around the patient that allow its perfect and continuous monitoring, representing Low consumption of used batteries.

The system provides for the use of devices working in full functionality mode (FFD) or reduced functionality (RFD). The first can work in two different forms within the Personal Area Network Network - PAN), both as FFD and RFD.

For a better understanding of the invention, accompanies different sheets of drawings, merely illustrative and not limiting it.

Brief explanation of the drawings

Figure 1 shows a representation of a monitoring system with only two personal area networks, distinguishing between devices that work in functionality complete and those that do it in reduced functionality.

Figure 2 shows a diagram of the System components and their range of use.

Figure 3 represents an ECG signal, while that figure 4 schematically represents a circuit of Acquisition of Electro Cardiogram (EGC) data within the known technique for said task and using, essentially, a DSP56F805 microprocessor.

Figure 5 is a diagrammatic representation of  blocks, within the known technique, of the ECG encoder in the DSP56F805 microcontroller.

Figure 6 represents a module that obtaining ECG signals encoded through the microcontroller of the previous figure, allows its transmission via wireless to the whole of the system of the invention.

Figure 7 is a representation, within the known technique, of a blood pressure sensor, based on the DSP56F803 microcontroller.

Figure 8 shows the interface module between the data obtained and encoded by the microcontroller of the previous figure for wireless transmission to the whole system of the invention.

Figure 9 details a device for Obtaining pulse oximetry. Uses a DSP56F803 microcontroller and an interface suitable for the wireless transmission to the whole data system obtained by said device.

Figure 10 shows an analogous mechanism of biometric data collection, this time from the breath of the patient, in which through a sensor they are obtained signals that are encoded and transmitted through the interface suitable for the whole system through communications wireless

Figure 11 shows a scheme for wireless coordination of the different devices that make up the present invention for the coordination of different devices that make up a personal area network. The Biomedical data of the different devices that their interfaces own transmit wirelessly are captured by a receiving device of said signals that transmits them to the system set, decoding said signals when corresponds, through a gateway or gateway.

Figure 12 shows a decoder like the shown in the previous figure, referring to the ECG signals.

Figures 13 and 14 represent diagrams with possible topologies of use of the invention, which may be used together or independently.

Figures 15 and 16 schematically represent the Ethernet and Bluetooth Gateways, respectively.

Detailed Explanation of the Invention

The present invention consists of a system wireless patient monitoring (1) whose data Biomedical (2) are evaluated in real time using devices (3, 4, 5, 6) grouped in a personal area network (7), and linked through different services to information recipients (8) that centralize them, decode them and transmit them to the whole of the system (1).

As shown in Figure 2, the system of the present invention can be subdivided into different ranges Application: wireless sensor devices (3, 4, 5, 6) that make up each personal area network (7), the data set personal biomedical (2), the control system of the different personal area networks (9) of biomedical data and the whole of system (1).

We analyze each of these levels in detail.

Wireless personal area networks (WPAN) they are designed as modular systems that provide connectivity to the set of subsystems to capture the biometric signals, allowing high scalability in the configuration of the system of the invention.

The invention characterizes different interfaces Biomedical data capture: device ECG-WPAN (3), BP-WPAN device (4), PO2-WPAN device (5) and Device breathing indicator-WPAN (6).

ECG-WPAN

The device or interface ECG-WPAN (3) provides an electro signal cardiogram, this is a sign of cardiac electrical activity (figure 3). The capture of an ECG is done through the potentials captured by various electrodes (11) (between 2 and 5 in configuration function) placed on the patient's skin at different points

Once the ECG signal is captured, it is sent to a  microcontroller (12) capable of processing very low signals amplitude (between 0.5 mV and 5 mV) coupled with a component of DC. The microcontroller allows you to work with the bandwidth selected for the monitoring system of 100 Hz, although other bandwidths can also be selected depending on the clinical application of the monitor, as between the range 0.5 to 100 Hz.

In the preferred embodiment of the invention, the microcontroller (12) used for monitoring is a Freescale DSP56F805 that is included in a device (3) that can take the patient with you (figure 4). The entrance of microcontroller converts the analog ECG signal into digital, performing interference filtering operations derived from muscle activity, coupling with other sources electrical and electrode.

For example, a FIR filter can be used Digital Pass-Band (14) with a cutoff frequency at 0.05 Hz and 100 Hz. A Causal Digital Filter of  Wiener (15) of order 10 to cancel the interference of others 50 Hz electrical sources.

Once digitized and filtered, the ECG signal is sent to the Peripheral Serial Interface (SPI) (13) of microcontroller (12) to be sent to the encoder in the form of ECG wave (figure 5). This coding optimizes traffic for work with 132-bit packets, the maximum allowed by the IEEE 802.15.4-2003 standard.

The channel coding of the signal obtained for wireless transmission it can be done with a channel encoder (16), for example a FreeScale MC13192, configured as RFD, this is to work as a device for reduced functionality This coding is done by DSSS modulation (Direct Sequence Spread Spectrum - Extension of Direct Sequence Spectrum) and configure the wireless link with the WPAN FDD coordinator (figure 1).

BP-WPAN

In blood pressure capture is used a Holter sensor (18) located in another device that carries the patient with me. This device used by most clinical applications, uses an oscillometric algorithm for Estimation of blood pressure, and is a non-intrusive mechanism. The blood pressure reading is done through a bull inflatable (17) located around the patient's left arm so that the vessels are compressed by swelling the bull.

The systolic blood pressure reading, diastolic and mean (SBP, DBP and MAP respectively) are read in the point where the Holter sensor is replaced.

Biomedical data obtained by the sensor Holter (18) of SBP, DBP and MAP reading are sent to a microcontroller (19) Freescale DSP56F803. The digital output of said microcontroller separates into two paths, one to perform its reading, another to filter the fluctuations on the reading derived from the internal pressure of the bull (17).

The digitized signal output corresponds to reality at two signals that in a time interval correspond to the oscillation of blood pressure (20) and the another to the internal pressure of the bull -CP- (21). Both signals have oscillations around 1 Hz and 0.04 Hz, respectively. So, to filter the CB signal of blood pressure oscillation (20) and remove the internal pressure component CP (21) from the bull, there are A FIR digital filter is placed in the microcontroller high-pass (22) with a cutoff frequency of 0.04 Hz. This process to eliminate the CP component in CB allows get two signals with a constant oscillation to perform the necessary comparisons and get a correct reference for the calculation of the real SBP, DBP and MAP.

Figure 7 shows the inputs and outputs of the microcontroller (19). The signals obtained SBP, DBP and MAP already real, they are coded to 16 bits being ready for transmission and be sent to a microcontroller (23) FreeScale MC13192 configured as RFD (Figure 8). This device performs channel coding for radio frequency transmission, the DSSS modulation and establishes the link with the FDD coordinator of the WPAN, according to figure 1.

PO2-WPAN

The pulse oximeter (PO2) is another non-invasive device for wide clinical use that monitors the percentage of hemoglobin (Hb) saturated with oxygen. The device for taking said biomedical data, as in In the previous cases, it is placed in the patient. It is a light probe (24) hooked to an earlobe or finger of the patient that is connected to a microcontroller (25), such as a FreeScale DSP56F803.

PO2 can also be used in clinical applications for blood flow measurement.

A probe (24) that measures absorption is used of light at two different wavelengths (650 nm and 805 nm) and that light is partially absorbed by hemoglobin in some amounts that are a function of oxygen saturation. Calculating these absorptions the microcontroller (25) is capable of estimate the percentage of Hb saturated with oxygen.

It should be noted that a PO2 does not give any indication about the ventilation of a patient, only their level of blood oxygen and therefore errors could occur reading considering that a high level of Hb saturated with oxygen It does not mean that the patient is breathing normally. In the present invention this problem is solved with the monitor of breathing.

The output of the PO2 sensor consists of two signals Hb saturation (26) and arterial flow (27). He microcontroller (25) is able to process input signals very weak (between 0.5 mV and 5 mV) and working with bandwidths between 0.05 and 100 Hz. In the preferred embodiment the bandwidth selected is 100 Hz.

Hb saturation readings and flow once  estimated and coded with 16 bits are sent to a microcontroller (28), such as a Freescale MC13192, configured reduced functionality or RFD (figure 9), so that this device performs channel coding for the transmission of radio frequency, DSSS modulation and establishes the link with the WPAN FDD coordinator (figure 1).

Breathing Indicator - WPAN

In certain clinical applications, in addition to monitor ECG (3), BP (4) and PO2 (5), it is necessary to validate if the patient is ventilated or not. In the present system This is done with a "YES or NO" indicator that Provide such information.

An anemometer (29) is placed in the tube of the artificial respirator (30) and connects to a microcontroller (31), such as a FreeScale DSP56F803, which performs the filtering of reading fluctuations, output amplification and comparison with a threshold of respiratory activity (figure 10). The System output is calculated through the application of following conditions on the digital anemometer reading (29) :

- S (n) > Th - -> Yes

- S (n) <Th - -> No

Where S (n) is the anemometer output (32) and Th is the breathing threshold (33) selected. In the preferred embodiment of the invention, said threshold (33) has been set to 1V (corresponding to a pressure of 0.5 kPa) The Figure 10 shows the implementation of the breathing indicator (6) with an Omron anemometer D6F-10A5-000 with sensor Unidirectional air flow.

Once the indicator is determined, it is coded in 8 bits and sent to a microcontroller (34), such as a FreeScale MC13192 configured as RFD (figure 10). Saying device performs channel coding for transmission via radio frequency, DSSS modulation and establishes the link with the FDD coordinator of the WPAN (figure 1).

WPAN coordination

A WPAN is a wireless network that provides connectivity between different signal capture systems biomedical (7) and the monitoring system coordinator (10). WPAN coordination (9) integrates the different devices detailed above and intercom using the IEEE 802.15.4-2003 protocol together with the program of management for the processing and presentation of timely data.

Said coordinator (9) performs the functions of: set the WPAN node indicator, quality indicator of the radio links with the different devices, indicator of battery consumption, avoid WPANs interference contiguous through the filtering of node indicators.

The Coordination of the Monitoring System

The System Coordinator (10) provides connectivity to the different WPAN (7) with the health information and monitoring systems. It integrates the different WPANs in the monitoring system and communicates them with the different health information and monitoring systems through two different types of gateways: Ethernet (36) and Bluetooth (37). In that practical implementation where there is only one WPAN, the System Coordinator (10) will also act as the coordinator
WPAN (9).

The monitoring system Coordinator acts as the end point of the communications of all  WPANs coordinators (9) (figure 1) and in realization favorite is built using a microcontroller (35) FreeScale MC 13193 configured as FDD (figure 11).

Said System Coordinator (10) performs in addition the following functions: detect and link with new WPANs detected, indicate the quality of the links with the different WPANs, indicate general network consumption, avoid interference between adjacent WPANs, assign channels of communication for each WPAN, generates the WPAN identifiers that are assigned to each patient and establishes the procedures of unique identification for each WPAN and, therefore, for each patient.

The Ethernet gateway or gateway (36) is connected to the System Coordinator (10) and is responsible for the translation of IEEE 802.15.4-2003 frames in Ethernet frames This translation is done with a microcontroller (38) FreeScale DSP56F804 (figure 15) that collects all WPAN data connected to the system coordinator and translates them to the IEEE 802.3 standard. This translation allows the integration with most existing networks, including WiFi, WiMax and ADSL since these allow to connect directly with Ethernet

The Bluetooth gateway (37) is connected to the system coordinator and is responsible for the translation of IEEE 802.15.4-2003 frames in Bluetooth frames. It is used to perform such translation in the preferred embodiment of the invention, a microcontroller (39) which collects all the frames of the different WPANs and translates them to Bluetooth (figure 16) This translation guarantees the integration of the system for example with a PDA (Personal Data Assistant - Assistant  Personal Data) for data presentation and connectivity, or with a mobile phone in order to connect the WPANs with any Health Information system through said personal devices

It is understood that in the present they can vary how many details do not alter or modify the content essential of the invention.

Claims (20)

1. Patient monitoring system, characterized by - use wireless connections using any convenient protocol, such as the IEEE protocol 802.15.4-2003 - include devices for each patient biomedical electrocardiogram data collection -ECG- (3), pulsi- oximeter -PO2- (4), blood pressure -BP- (5) and Indicator of breathing -IR- (6) - in which a personal area network is formed wireless (7) that groups said data collection devices Biometric (3,4,5,6) with a Coordination (9) of Area Networks Wireless Personnel (WPAN), said WPAN Coordination (9) establishing a node indicator for the System, indicating the quality of the radio signals for the links of the different devices (3, 4, 5, 6), establishing filter media of interference with other contiguous WPANs, and indicating the Battery consumption of each device. - a coordinator (10) of the different WPANs to provide and display the information and data of monitoring carried out, transmitting the appropriate messages to the different display devices connected to the system or monitoring services. 2. Patient monitoring system according to claim 1, characterized in that said ECG device (3) by means of a plurality of electrodes (11) captures the cardiac electrical activity whose signal is sent to a microcontroller (12), such as a FreeScale DSP56F805, which digitizes the signal, filters the interferences derived from muscular activity and coupling with other electrical sources of said electrodes (11), and sends said digitized and filtered signal to a Peripheral Interface Series -SPI- (13) of said microcontroller (12) for shipment in wave form. 3. Patient monitoring system according to the preceding claim, characterized in that a channel coding is obtained for the radio frequency transmission of the output signal of said microcontroller (12) by means of a microcontroller (16) channel encoder and source (using waveform coding techniques), such as a FreeScale MC13192, by means of DSSS (Direct Sequence Spectrum Enlargement) modulation that configures the wireless link with said WPAN coordinator (7). 4. Patient monitoring system according to claims 2, 3 and 4, characterized in that the signal filtering of said microncontroller (12) is performed by a digital FIR-Band FIR filter (14) with a cutoff frequency between 0 , 05 Hz and 100 Hz. 5. Patient monitoring system according to claims 2 to 4, characterized in that the signal filtering of said microncontroller (12) is additionally carried out by means of a Wiener digital causal filter (15) of order 10, source interference canceler 50 Hz electrical 6. Patient monitoring system according to claim 1, characterized in that said BP device (4) uses an inflatable bull (17) that collects systolic blood pressure data -SBP-, diastolic -DBP- and average -MAP- by means of a sensor (18) type Holter using calibration by diversity of paths. 7. Patient monitoring system according to the preceding claim, characterized in that said data taken by said sensor (18) is used by a microcontroller (19), for example a FreeScale DSP56F803 producing a blood pressure oscillation signal -CB- (20) and another -CP- (21) of internal pressure of said bull (17). 8. Patient monitoring system according to claims 6 and 7, characterized in that a channel coding is obtained for the radio frequency transmission of the output signal of said microcontroller (19) by means of a microcontroller (23) encoder of channel, such as a FreeScale MC13192, by means of DSSS modulation (Direct spectrum emission sequence) that configures the wireless link with said WPAN coordinator (7). 9. Patient monitoring system according to claims 6 to 8, characterized in that a high-pass FIR digital filter (22) with a cut-off frequency of 0.04 Hz is used. 10. Patient monitoring system according to claim 1, characterized in that said PO2 device (5) uses a light probe (24) whose absorptions are encoded by a microcontroller (25), such as for example a FreeScale DSP56F803, resulting in a Hb-hemoglobin- saturation signal (26) and another arterial flow signal (27). 11. Patient monitoring system according to the preceding claim, characterized in that a channel coding is obtained for the radio frequency transmission of the output signal of said microcontroller (25) by means of a channel encoder microcontroller (28), such as a FreeScale MC13192, by means of DSSS modulation (Direct spectrum emission sequence) which configures the wireless link with said WPAN coordinator (7). 12. Patient monitoring system according to claims 10 and 11, characterized in that said microcontroller (25) works at a selected bandwidth of 100 Hz. 13. Patient monitoring system according to claim 1, characterized in that said Respiration Indicator device (6) uses an anemometer (29) connected to an artificial breathing tube (30) whose signal is encoded by a microcontroller (31) , such as a FreeScale DSP56F803, whose output signal -S (n) - (32) is compared with a threshold signal -Th- (33) to obtain a logical value of Yes or No as a result of said breathing indicator (6 ). 14. Patient monitoring system according to the preceding claim, characterized in that a channel coding is obtained for the radio frequency transmission of the output signal of said microcontroller (31) by means of a channel encoder microcontroller (34), such as a FreeScale MC13192, by means of DSSS modulation (Direct spectrum emission sequence) which configures the wireless link with said WPAN coordinator (7). 15. Patient monitoring system according to claims 13 and 14, characterized in that said breathing threshold -Th- (33) has been set at 1 V, corresponding to a pressure of 0.5 KPa. 16. Patient monitoring system according to any of the preceding claims, characterized in that an Ethernet gateway (36) is included that translates the IEEE 802.15.4-2003 frames into Ethernet frames by means of a microcontroller (38), such as a FreeScale DSP56F804 , which collects all data from all connected WPANs (7) and translates them to the IEEE 802.3 standard 17. Patient monitoring system according to any of the preceding claims, characterized in that a Bluetooth gateway (37) is included that translates the IEEE 802.15.4-2003 frames into Bluetooth frames, by means of a microcontroller (39), such as a FreeScale MC9328MX1, which collects all data from all WPANs (7) and translates them to Bluetooth. 18. Patient monitoring system according to the preceding claims, characterized in that said Coordination of the Monitoring System (10) that integrates the different WPANs (7) into the system and communicates them with the different health information and monitoring systems, is constructed by means of a microcontroller (35), such as a FreeScale MC 13193, which detects and links with new detected WPANs, indicates the quality of the links with the different WPANs, indicates the general consumption of the network, avoids interference with adjacent WPANs, assigns channels of communication for each WPAN, generates the identifiers of the WPAN assigned to each patient. 19. Patient monitoring system according to the preceding claim, characterized in that when there is only one WPAN, said WPAN controller (9) is the Coordination of the Monitoring System (10). 20. Patient monitoring system according to any of the preceding claims, characterized in that different constructions can be made in which only one or more of the biomedical data collection devices (3, 4, 5, 6) are used in one or more patients