WO2006006107A1

WO2006006107A1 - Modular patient monitoring

Info

Publication number: WO2006006107A1
Application number: PCT/IB2005/052191
Authority: WO
Inventors: Markus WOHLSCHLÄGER
Original assignee: Philips Intellectual Property & Standards Gmbh; Koninklijke Philips Electronics N. V.
Priority date: 2004-07-07
Filing date: 2005-07-01
Publication date: 2006-01-19

Abstract

The present invention provides a modular patient monitoring system that has a base station and a coupling unit as well as a number of application specific transducers for acquisition and generating of patient monitoring data. The various transducers are accomplished with digital signal processing means allowing for digital signal transmission between the transducers and the coupling unit. Coupling of the various different types of transducers to the coupling unit can therefore be based on a common interface allowing for larger flexibility of a patient monitoring system. In particular, the number of configuration options and extension options as well as upgrade support can be significantly enhanced.

Description

Modular patient monitoring

The present invention relates to the field of patient monitoring and in particular without limitation to the field of fetal and maternal monitoring.

Modern patient monitoring systems provide acquisition and processing of various physiological parameters of a patient. Typically, a patient monitoring system has a plurality of dedicated sensors and transducers, each of which being adapted to acquire a distinct physiological parameter. In order to provide a large degree of flexibility and patient comfort, acquisition of physiological patient data and subsequent processing and analysis of the acquired data is separately implemented by means of a base station and a plurality of dedicated sensors and transducers being connected to the base station. Preferably, the sensors and transducers for data acquisition are designed as light weight and compact units allowing for an easy handling, convenient application to the patient's body and thus providing a maximum of patient comfort during patient monitoring.

There exists a large variety of different sensors and transducers that are particularly designed for acquisition of distinct parameters and specific parameter ranges. For example in the framework of fetal and maternal diagnostic, sensors and transducers might be implemented as ultrasound transducers (US), TOCO transducers and transducers for electro-cardiograms (ECG). US transducers provide monitoring of a fetal heart rate or fetal movement, TOCO transducers provide measurement of uterine activity and ECG transducers might be implemented as scalp electrodes for fetal related measurements and as conventional electrodes for maternal related measurements. Moreover, various other transducers and sensors can be realized for e.g. measurement of blood oxygen saturation values (SpO₂ values) and non-invasive acquisition of blood pressure (NIBP). Since each one of the various sensors and transducers for acquisition of patient monitoring signals is specifically designed for acquisition of one dedicated physiological parameter, the base station and the various transducers have to be well coordinated.

Typically, each type of transducer or sensor generates a transducer or sensor specific signal that has to be processed and analyzed by the base station in an appropriate way. Therefore, a base station typically provides transducer- and sensor type specific connectors or plug sockets. Each one of these type specific connectors is designed for coupling to a sensor or transducer of an appropriate type. For example, the Series 50 XM fetal and maternal monitoring systems commercially distributed by Philips Medical Systems provide base stations for data analysis providing a distinct number of connectors of various types.

For example, a base station may have two connectors for ultrasound sensors, one connector for a TOCO transducer and two further connectors for maternal and fetal ECG transducers. Each of these connectors or plug sockets might be color encoded or mechanically coded in order to exclusively enable coupling of an appropriate sensor or transducer. Since the various types of transducers or sensors provide different types of monitoring signals and require different triggering signals, each sensor type must be connected to the appropriate connector of the base station.

Although, these commercially available patient monitoring systems already incorporate acquisition and analysis of a plurality of various physiological parameters, these systems are limited with respect to flexibility and universality. In particular, the sensor type dedicated connectors of the base station effectively limit the number of sensors that can be connected to the patient monitoring system. Also, existing patient monitoring systems only provide a limited extension capability. For example, patient monitoring systems known in the prior art may not be capable of a coupling of sensors and transducers that are to be developed and that are not yet available. In this way, the inventive system provides a sufficient upgrade functionality. Moreover, commercially available patient monitoring systems might not be adaptable to arbitrary and extraordinary patient monitoring situations, such as e.g. fetal monitoring of twins or even triplets. The present invention therefore aims to provide a patient monitoring system providing improved flexibility and improved extension options.

The present invention provides a patient monitoring system that comprises a base station and at least a first and a second transducer that are to be coupled to the base station. The base station is adapted to receive at least a first and a second patient monitoring signal and the base station further has a coupling unit. This coupling unit has at least a first and a second connector. The at least first transducer of the patient monitoring system is adapted to acquire first physiological patient data and to generate a corresponding first patient monitoring signal. The first transducer further provides and transmits the generated first patient monitoring signal to the base station. In a similar way, the at least second transducer is adapted to acquire second physiological patient data and to generate a respective second patient monitoring signal that has to be provided and transmitted to the base station for signal analysis and parameter illustration.

Coupling of the at least first and second transducers is implemented via a coupling unit that has at least a first and a second connector. These connectors are standardized and provide universal coupling of any one of the at least first and second transducers to any one of the at least first and second connectors, irrespectively of the type of transducer and the signal type generated by the transducer. Hence, the at least first transducer may be coupled to the base station either by means of the at least first or the at least second connector of the coupling unit. In this way each transducer or sensor type can be arbitrarily coupled to any one of the connectors or plug sockets of the coupling unit.

By means of this universal and arbitrary coupling between transducers and the base station, i.e. the coupling unit of the base station, the flexibility and extension capability of the inventive patient monitoring system can be obviously enhanced compared to patient monitoring systems of the prior art. Hence, the base station of the patient monitoring system can be coupled to an eligible number of transducers of the same or different type.

Depending on the monitoring requirements that may be specified by the constitution of the patient, for example two or three ultrasound transducers and an equal number of ECG transducers may be coupled to the base station. In another configuration, the base station might be coupled to two ultrasound transducers, one

TOCO transducer, two ECG transducers and a transducer for NIBP measurements. The total amount of transducers that may be coupled to the base station is only limited by the amount of connectors of the coupling unit. This absolute number of transducers represents the only configuration limitation of the inventive patient monitoring system. Among this absolute number of transducers, an operator or user of the inventive patient monitoring system may arbitrarily choose among a plurality of different types of transducers that can be arbitrarily coupled to the base station. Hence, the plurality of configuration options is no longer limited and influenced by the type of transducer or sensor.

Moreover, overall handling of the patient monitoring system is facilitated, because the operator no longer has to pay attention that a transducer is connected to a corresponding connector or plug socket of the base station.

According to a further preferred embodiment of the invention, each one of the at least first and second patient monitoring signals is indicative of the type of the respective first and second transducers and the type of respective acquired physiological patient data. Necessary information of the type of signal is therefore transmitted by the signal itself instead of transmitting different types of signals to signal specific connectors of the base station. Consequently, each transducer type provides a transducer specific signal that allows for identification of the respective transducer. Hence, the base station and/or its coupling unit are adapted to identify a patient monitoring signal received from a transducer and to assign the identified patient monitoring signal to corresponding signal analysis and signal illustration and representation means.

According to a further preferred embodiment of the invention, the at least first and second patient monitoring signals are digital signals that are transmitted by means of a predefined signal transmission protocol. This implies that the at least first and second transducers comprise signal processing means for converting acquired analog signals into digital signals. Furthermore, transmission of digital signals between the at least first and second transducers and the coupling unit is advantageous with respect to numerous aspects.

First of all the amount of data to be transferred between transducers and base station can be effectively reduced. When for example the transducer itself is capable of processing of e.g. heart rate monitoring signals, only the resulting heart rate instead of each single acquired heart rate signal has to be transmitted. Second, digital signals are rather insensitive to electromagnetic interference (EMI) that might spoil the quality of analog signals, in particular when long wires between transducers and base station are used. Third, dedicated sensors, like ultrasound sensors or transducers, may require a relatively high signal bandwidth that must be supported by the base station when analog signal transmission is implemented. Moreover, in this case dedicated transmission means, like shielded cables have to be used in order to guarantee signal and data integrity. Additionally, by making use of digital signal transmission, the base station no longer has to generate and to transmit an transducer specific analog signals that are required to drive a particular transducer. Transmission of the digital signals between the transducers and the base station is preferably implemented by making use of a predefined signal transmission protocol, such as commercially available bus protocols, e.g. a CAN-bus protocol. In this way, the transducers of different type can be identified by means of transducer specific patient monitoring signals. Moreover, digital signal transmission requires, that the at least first and second transducers are implemented as active transducers. For example, an ultrasound transducer then has to autonomously generate ultrasound signals and to transfer received ultrasound echo signals into digital signals that are suitable for transmission to the base station.

According to a further preferred embodiment of the invention, the at least first and second connectors of the coupling unit comprise equal mechanical coupling means for any one of the at least first and second transducers. The connectors are preferably implemented as mechanically coded plug sockets that provide connecting of transducers to the coupling unit by simply plugging a respective plug of a transducer into any one of the plug sockets. Preferably, plug sockets of the coupling unit as well as plugs representing a distal cable end of any one the transducers, are mechanically and electrically standardized, such that any plug can be connected to any one of the plug sockets provided by the coupling unit.

In contrast to prior art solutions, there no longer exists a coupling of specific transducers to dedicated plug sockets or connectors of the coupling unit. Moreover, the inventive coupling mechanism makes use of a single type of standardized plugs and plug sockets that allows for universal coupling and configuring of the patient monitoring system. According to a further preferred embodiment of the invention, the coupling unit is implemented as a separate device and features a separate housing. In this embodiment, the coupling unit is coupled to the base station by means of a data transmission cable. Hence, the coupling unit becomes a modular part of the patient monitoring system and provides efficient coupling of a plurality of transducers to the base station. Preferably, the data transmission cable connecting the coupling unit and the base station of the patient monitoring system, is implemented as a serial data transmission cable.

Consequently, the coupling unit comprises data serialization means in order to couple a number of patient monitoring signals that are received in a parallel way into a serial data stream. Moreover, by implementing the coupling unit as a stand alone device, flexibility of the entire patient monitoring system may be further enhanced. In this way, a coupling unit and numerous connected transducers may be coupled to different types of base stations. Additionally, the patient monitoring system is based on a complete modular concept that allows for universal and flexible replacement and renewal of particular modules and components.

According to a further preferred embodiment of the invention, the at least first and second transducers and the coupling unit further comprise means for signal synchronization. This is particularly applicable, when for example multiple ultrasound transducers are coupled to the coupling unit. The synchronization means might be based on a master clock signal that is transferred from the coupling unit to any one of the connected transducers. This master clock signal is then recovered individually by each transducer in order to coordinate transmission of acquired and generated patient monitoring signals. In this way transducer cross interference can be effectively prevented.

According to a further preferred embodiment of the invention, the at least first and second patient monitoring signals are indicative of fetal and/or maternal diagnostic data. Hence, the patient monitoring system is particularly implemented as a fetal and/or maternal monitoring system providing valuable support for obstetrical care. However, the inventive patient monitoring system may not be restricted to the field of fetal and maternal monitoring. It may be universally implemented in any diagnostic field, where simultaneous acquisition of various physiological parameters have to be acquired, processed, analyzed and illustrated.

In another aspect, the invention provides a transducer for a patient monitoring system. The patient monitoring system has a base station for receiving at least a first and a second patient monitoring signal. The patient monitoring system further has a coupling unit that has at least a first and a second connector. The transducer comprises digital signal processing means for generating at least one of the at least first and second patient monitoring signals and means for coupling the transducer to any one of the at least first and second connectors of the coupling unit. Typically, each transducer of the patient monitoring system is dedicated for acquisition of a distinct physiological parameter of a patient, like e.g. heart beat rate, blood oxygen saturation, blood pressure, ECG signals. However, a transducer is not principally restricted to provide only one particular type of parameter. Moreover, a single transducer may also be adapted to provide acquisition of a multitude of different parameters, like e.g. TOCO and ECG parameters. Depending on the specific type of application of the patient monitoring system, specific transducers may be coupled to the patient monitoring system in order to provide a maximum of flexibility and configuration options. In particular, transducers, the base station and the coupling unit for the transducers may be separately commercially distributed. The end user may then arbitrarily configure the patient monitoring system by combining dedicated transducers to the coupling unit and/or to the base station.

According to a further preferred embodiment of the invention, the transducer further comprises indication means that are adapted to visually indicate the quality of the at least one signal that is generated by the transducer. Additionally or alternatively, the transducer comprises means for generating audibly perceptible signals that are indicative of the quality of the generated patient monitoring signal. This is particularly advantageous, when a plurality of different transducers is coupled to the base station.

For example when acquiring ultrasound echo signals, a respective ultrasound transducer or sensor has to be positioned at an appropriate location of the patient's body. The acquired ultrasonic echo signals are particularly sensitive to the position of the ultrasound sensor. Especially, when a plurality of ultrasound sensors is in operation it might be difficult to find out which one of the ultrasound sensors produces a patient monitoring signal of inacceptable quality. Since the inventive transducers comprise signal processing means, the quality of a generated signal can already be determined by means of the transducer itself. It is therefore advantageous, that the transducer itself is also capable to provide respective signal quality measures to the operator of the patient monitoring system that allows for a proper attachment of the sensor to the patient's body.

Additionally, the indication means may not only provide a quality measure of an acquired parameter, but may further be adapted to indicate the measured parameter value directly to the operator of the patient monitoring system. Since the transducer itself comprises signal processing means, a determined parameter can be directly outputted in a perceptible way, either by visualizing or by generating respective acoustic output. For example, a heart rate can be provided as a sequence of beeps, each of which corresponding to a single heart beat. Additionally, the heart rate can be visualized as a number representing a parameter like heart beats per minute.

According to a further preferred embodiment of the invention, the transducer further comprises at least a third connector for coupling of at least a second transducer to the coupling unit. In this embodiment, each transducer is not only capable of communicating with a coupling unit but also of communicating with another transducer. In this way the number of connectors of the coupling unit can be effectively reduced while simultaneously enhancing the overall number of transducers that can be coupled to the base station. Hence, a large amount of single transducers can be coupled in a sequential way.

For example coupling a second transducer to a first transducer and coupling the first transducer to the coupling unit effectively provides coupling of both the first and the second transducer to the coupling unit and hence to the base station. In this way, the maximum number of transducers that can be coupled to the coupling unit might only be limited by the utilized signal transmission protocol. Moreover, a plurality of transducers can be coupled to the coupling unit either by making use of a star topology or a daisy chain topology.

In another aspect the invention provides a base station of a patient monitoring system. The patient monitoring system has at least a first and a second transducer for generating at least respective first and second patient monitoring signals. The base station comprises a coupling unit that has at least a first and a second connector for coupling of any one of the at least first and second transducers to the coupling unit. The base station further comprises means for receiving of the at least first and second patient monitoring signals from the coupling unit. In principle, the base station provides analysis of the received signals in order to produce visible and/or audible output being informative of various physiological parameters of the patient. The coupling unit of the base station may be implemented as an integral part of the base station or alternatively as a stand alone device. In still another aspect the invention provides a coupling unit of a base station of a patient monitoring system. The patient monitoring system has at least a first and a second transducer for generating at least respective first and second patient monitoring signals that are transmitted from the at least first and second transducers to the base station. The inventive coupling unit comprises at least a first connector for coupling of any one of the at least first and second transducers to the coupling unit and comprises at least a second connector for coupling of any one of the at least first and second transducers to the coupling unit. In this way the coupling unit effectively provides arbitrary coupling of any one of the at least first and second transducers to any one of the at least first and second connectors of the coupling unit. Consequently, an arbitrary transducer can be connected to any one of the connectors or plug socket of the coupling unit, irrespectively of the type of the patient monitoring signal.

According to a further preferred embodiment of the invention, the coupling unit comprises an insulation unit for providing galvanic separation between the base station and any one of the at least first and second transducers. In this way a required safety electrical insulation can be effectively realized for all connectable transducers by making use of a single insulation unit provided by the coupling unit or by the base station. The electrical insulation unit may for example by implemented by mean of an opto-coupling device. In particular, by making use of digital signal transmission, the required electrical insulation unit can be implemented in the coupling unit or the base station instead of implementing a separate insulation unit for each transducer or sensor. This effectively allows to reduce costs and to further reduce weight and size of the transducers. According to a further preferred embodiment of the invention, the coupling unit further comprises a serialization unit for transforming the at least first and second patient monitoring signals into a serial data stream that is transmitted to the base station or to the analysis-, illustration- and representation means of the base station. This serialization unit effectively provides coupling of a plurality of patient monitoring signals that are received in parallel, into a single stream of serial data. In this way the coupling unit and the base station can be separately distributed as stand alone devices thus allowing for a modular concept of the patient monitoring system.

In the following preferred embodiments of the invention will be described by way of example, by making reference to the drawings in which:

Figure 1 shows a schematic illustration of the patient monitoring system, Figure 2 illustrates a block diagram of a transducer,

Figure 3 shows a block diagram of a coupling unit,

Figure 4 shows a block diagram of four transducers being coupled to a coupling unit in a star topology,

Figure 5 shows a block diagram of three transducers being coupled to the coupling unit in a daisy chain configuration.

Figure 1 shows a schematic illustration of a patient monitoring system 1 that is applied to a patient 12. The patient monitoring system 1 has a first and a second transducer 20, 22, a coupling unit 10 and a base station 14. The coupling unit 10 has a plurality of connectors 64, 66 that provide coupling of the transducers 20, 22 to the coupling unit. The transducers 20, 22 are typically dedicated to acquisition of a distinct physiological parameter of the patient 12. For example, the transducers 20, 22 may be adapted for acquisition of ultrasound echo signals, of TOCO signals being indicative of labor pressure, ECG signals and the like.

In figure 1, the transducers 20, 22 feature a similar geometric shape and they may both provide ultrasound signals that are indicative of a fetal heart rate or fetal movement of a pregnant woman 12. As illustrated, the first transducer 20 is connected to the coupling unit 10 by means of a plug 21 being plugged into the plug socket or connector 64. Similarly, the second transducer 22 is connected by means of the plug 21 with the connector 66 of the coupling unit 10. Here, the various connectors 64, 66 of the coupling unit 10 are not dedicated to a specific type of transducer. For example, transducers implemented as ECG electrodes may also be coupled to the connectors 64 or 66. Moreover, the second transducer 22 may be coupled to connector 64 and transducer 20 may be coupled to connector 66.

As shown in figure 1, the coupling unit 10 provides two additional connectors that provide the same functionality as the connectors 64, 66. Additional arbitrary transducers may therefore be coupled to the coupling unit 10 in the same way as the illustrated transducers 20, 22.

The coupling unit 10 is further connected to the base station 14 by means of the serial data cable 62. The base station 14 comprises a display 16 and a control panel 18 in order to visualize the received patient monitoring signals. Additionally, the base station may provide means for printing patient monitoring data and to control the functionality of the transducers 20, 22.

In the illustrated embodiment the patient monitoring system 1 is implemented as a modular system that has three different types of modules: transducers, a coupling unit and a base station. By implementing the patient monitoring system 1 as a modular system a maximum of flexibility, universality, versatility and configuration options can be realized. Moreover, an exchange of a single modular component or an extension, e.g. combining a new transducer to the coupling unit 10, can be easily implemented. Alternatively, the coupling unit 10 might be entirely implemented into the base station 14. In such an embodiment the patient monitoring system only features two different types of components, namely various transducers that can be coupled to the base station. In this case the entire functionality of the coupling unit is integrated into the base station. Figure 2 illustrates a block diagram of an inventive transducer 20. The transducer 20 has a sensor control unit 30, a clock recovery unit 32, a signal processing unit 36 and a signal indicator 34. The sensor control unit 30 further has a sensor 44, a sensor activator 38, a signal filter 42 and an analog digital converter 40. The signal processing unit 36 is further connected to a cable that has a plug 21 for coupling of the transducer 20 to the coupling unit 10.

The sensor 42 is dedicated to acquisition of a distinct physiological parameter of the patient 12. For example, the sensor 42 is implemented as an ultrasound transducer. In this case the sensor not only detects ultrasound echo signals from the human body 12, but also generates and transmits ultrasound signals to a designated volume of the patient 12. Preferably, the sensor 44 is triggered by means of the sensor activator 38 in order to generate a predefined sequence of e.g. ultrasound signals. The sensor activator 38 in turn receives control signals from the clock recovery unit 32 that is connected to the signal processor coordinating signal transmission between the transducer 20 and the coupling unit 10, hence the base station 14. In this way activation of an ultrasound transducer 44 can be effectively controlled and triggered by means of the coupling unit 10. In this way, multiple transducers 20, 22 can be coupled to a base station 14 by simultaneously guaranteeing elimination of cross interference of the various patient monitoring signals generated by the plurality of transducers 20, 22. The sensor 44 is implemented as an analog device that provides an analog voltage output that is indicative of the magnitude of the dedicated physiological parameter. The analog output generated by the sensor 44 is transmitted to the signal filter 42 in order to apply an appropriate signal filtering. Thereafter, the filtered analog signal is inputted into the analog digital converter 40 in order to convert the analog signal into a digital signal. This is only one example of how to implement the sensor control unit. Various other constellations of sensor activation signal filtering and analog digital converting means are conceivable. The sensor control unit 30 is implemented to receive a clock signal from the clock recovery unit 32, to trigger the sensor 44 in order to acquire a respective analog signal and to finally provide the digitally converted signal to the signal processor 36.

The signal processor 36 controls signal and data transmission between the transducer 20 and the coupling unit 10. The signal processor also controls the signal indicator 34 that is indicative of the quality of the generated patient monitoring signal. Preferably, the signal indicator 34 comprises indication means, such as a simple display, or color encoded blinking lights in order to visually illustrate the quality and hence the reliability of the generated patient monitoring signal. Additionally, the signal indicator 34 may generate perceptible audible signals that indicate an inacceptable quality of the generated signal.

The signal processor 36 also provides a pre-processing or the acquired signal and therefore allows to effectively reduce the data traffic between the transducer 20 and of the coupling unit 10. For example, when the transducer 20 is adapted to acquire a heart beat frequency, the signal processor 36 is able to calculate a heart beat frequency by receiving sequential heart beat signals and by performing the appropriate calculation operation. Consequently, a digitized signal instead of an analog wave has to be transmitted to the coupling unit 10 and the base station 14. Also, the data processing load of the coupling unit 10 and/or the base station can be effectively reduced, which is particularly advantageous when a plurality of transducers 20, 22 is coupled to a single base station 14.

The transducer 20 may further comprise a memory module that allows for an efficient calibration of a transducer. In this way calibration of the patient monitoring system 1 can be entirely implemented by separately calibrating each transducer 20, 22. Since the transducers 20, 22 comprise digital signal processing means the calibration can be performed entirely digitally. This allows to produce the single sensors with a larger tolerance margin which is advantageous for a minimization of production costs.

Figure 3 illustrates a block diagram of the coupling unit 10. The coupling unit 10 has a connector array 60, a memory 58, a clock module 50, a processing unit 54, an insulation unit 56 and a serial converter 52. The coupling unit 10 can be connected to the base station 14 by means of the serial data cable 62. The insulation unit 56 effectively provides a galvanic separation between the coupling unit 10 and the base station 14. Consequently, also the transducers 20, 22 that are to be coupled to the coupling unit 10 are galvanically separated from a power supply of the base station 14.

The processing unit 54 provides a post processing of received digital monitoring signals and the memory 58 allows for storage of processed and/or post processed received signals. Additionally, the memory 58 may serve as a data buffer.

The connector array 60 has a number of connectors 64, 66 that provide universal coupling of any type of transducer 20, 22 to the coupling unit 10. Hence, every connector 64, 66 of the connector array 60 features the same geometry and the same electrical functionality. Any transducer 20 can be coupled to any one of the connectors 64, 66 by means of a plug 21. The connector array 60 and the parallel connectors 64, 66 are all connected to the serial converter 52 that serves to convert the numerous patient monitoring signals of different transducers 20, 22 into a serial data stream. The serial converter 52 is connected to the processing unit 54 and provides a plurality of different patient monitoring signals in form of a single serial data stream.

The clock module 50 provides a clock signal that can be effectively used to synchronize operation of the various transducers 20, 22 that are coupled to the coupling unit. In this way, cross interference of signals received from different transducers 20, 22 can be effectively eliminated. Moreover, by means of the clock signal, sequential time intervals of the serial data stream can be uniquely assigned to different transducers 20, 22. Moreover, the clock module 50 and the corresponding clock signal provide a basis for the signal transmission protocol. Figure 4 illustrates an embodiment, where four separate transducers 20,

22, 24, 26 are separately coupled to the coupling unit 10. This arrangement reflects a star topology that provides an entirely separate control of each one of the four transducers 20, ..., 26. In this case, the coupling unit 10 has to provide at least four separate connectors, each of which providing a coupling between the coupling unit 10 and one of the transducers 20, ...., 26.

In figure 5 a daisy chain topology is illustrated. Here, the coupling unit 10 is connected to a first transducer 20 which in turn is connected to a second transducer 22, that in turn provides coupling to a third transducer 24. In this daisy chain configuration, each transducer 20, 22, 24 has to provide at least first and second coupling means for coupling to the coupling unit and for coupling to another transducer, respectively. Compared to the embodiment of figure 4, in figure 5 a plurality of transducers 20, 22, 24 can be effectively coupled to a single connector of the coupling unit 10. In this case the data transmission protocol used for signal transmission between the coupling unit and the single transducers 20, 22, 24 has to support the illustrated daisy chain configuration.

Moreover, a maximum of universality and flexibility can be implemented by combining both configurations, the star topology illustrated in figure 4 and the daisy chain topology illustrated in figure 5.

By making use of digital signal processing performed by means of the transducers themselves, the flexibility, versatility and the number of configuration options of a patient monitoring system can be greatly enhanced. Moreover, digital signal processing allows for the realization of a highly implemented modular concept for a patient monitoring system. By implementing signal transmission between various transducers and a coupling unit by means of a signal transmission protocol, such as a bus protocol, coupling of application specific transducers to the coupling unit can be realized on the basis of a common interface.

LIST OF REFERENCE NUMERALS:

1 patient monitoring system

10 coupling unit

12 patient

14 base station

16 display

18 control panel

20 transducer

21 plug

22 transducer

24 transducer

26 transducer

30 sensor control unit

32 clock recovery unit

34 signal indicator

36 signal processor

38 sensor activator

40 analog digital converter

42 signal filter

44 sensor

50 clock module

52 serial converter

54 processing unit

56 insulation unit

58 memory

60 connector array

62 serial data cable

64 connector

66 connector

Claims

CLAIMS:

1. A patient monitoring system (1) comprising: a base station (14) for receiving at least a first and a second patient monitoring signal, the base station having a coupling unit (10), the coupling unit having at least a first (64) and a second (66) connector, - at least a first transducer (20) for providing of the first patient monitoring signal, the at least first transducer being adapted to be coupled to any one of the at least first and second connectors (64, 66) of the coupling unit, at least a second transducer (22)for providing of the second patient monitoring signal, the at least second transducer being adapted to be coupled to any one of the at least first and second connectors (64, 66) of the coupling unit.

2. . The patient monitoring system (1) according to claim 1, wherein each one of the at least first and second patient monitoring signals are indicative of the type of the respective first (20) and second (22) transducers.

3. The patient monitoring system (1) according to claim 1, wherein the at least first and second patient monitoring signals are digital signals being transmitted by means of a predefined signal transmission protocol.

4. The patient monitoring system (1) according to claim 1, wherein the at least first and second connectors of the coupling unit comprise equal mechanical coupling means (64, 66) for any one of the at least first and second transducers (20, 22).

5. The patient monitoring system (1) according to claim 1, wherein the coupling (10) unit has a separate housing and wherein the coupling unit is coupled to the base station (14) by means of a data transmission cable (62).

6. The patient monitoring system (1) according to claim 1, wherein the at least first and second transducers (20, 22) and the coupling unit (10) comprise means for signal synchronization.

7. The patient monitoring system (1) according to claim 1, wherein the at least first and second patient monitoring signal are indicative of fetal diagnostic data.

8. A transducer (20, 22) for a patient monitoring system (1), the patient monitoring system having a base station (14) for receiving at least a first and a second patient monitoring signal and a coupling unit (10), the coupling unit having at least a first and a second connector (64, 66), the transducer comprising: - digital signal processing means (36) for generating at least one of the at least first and second patient monitoring signals, means for coupling (21) the transducer to any one of the at least first and second connectors (64, 66) of the coupling unit.

9. The transducer (20, 22) according to claim 8, further comprising indication means (34) being adapted to visually or audibly indicate the quality of the at least one signal generated by the transducer.

10. The transducer (20, 22) according to claim 8, further comprising at least a third connector for coupling of at least a second transducer to the coupling unit.

11. A base station (14) for a patient monitoring system (1), the patient monitoring system having at least a first and a second transducer (20, 22) for generating at least respective first and second patient monitoring signals, the base station comprising: a coupling unit (10) having at least a first and a second connector (64, 66) for coupling of any one of the at least first and second transducers (20, 22) to the coupling unit, - means for receiving of the at least first and second patient monitoring signal from the coupling unit.

12. A coupling unit (10) for a base station (14) of a patient monitoring system (1) having at least a first and a second transducer (20, 22) for generating at least respective first and second patient monitoring signals being transmitted to the base station, the coupling unit comprising: at least a first connector (64, 66) for coupling of any one of the at least first and second transducers to the coupling unit, at least a second connector (64, 66) for coupling of any one of the at least first and second transducers to the coupling unit.

13. The coupling unit (10) according to claim 12, further comprising an insulation unit (56) for providing galvanic separation between the base station (14) and any one of the at least first and second transducers (20, 22).

14. The coupling unit (10) according to claim 12, further comprising a serialization unit (52) for transforming the at least first and second patient monitoring signals into a serial data stream being transmitted to the base station (14).