Patient monitor sensor type auto configuration

A method and system that allows various sensor types to be connected to common input ports of a patient monitor. The system includes a data acquisition module that identifies the type of sensor connected to each one of a plurality of input ports. Once the sensor type has been identified, the data acquisition module configures amplification circuits and input circuits such that the output signal from the sensor is properly received and amplified within the patient monitor. The properly amplified output signal from the sensor, along with a sensor identifier, is supplied to a controller of the patient monitor. In this manner, the patient monitor can identify the type of sensor connected to each input port and properly display the conditioned output signal from the sensor.

BACKGROUND

The present disclosure generally relates to the field of patient monitoring. More specifically, the present disclosure relates to a patient monitor that includes one or more multi-function input ports that allow more than one type of sensor to be connected to each of the input ports.

Patient monitoring systems may incorporate a wide range of modality medical processes that are available to examine a patient's condition and health. Patient monitoring systems are able to receive various different types of physiological data obtained from sensors connected to a patient. Patient monitors can be configured to receive and analyze various different types of physiological data from a patient, such as pulse oximetry (SpO2), cardiac output (CO), temperature, invasive blood pressure, non-invasive blood pressure (NIBP), oxygen saturation, as well as other physiological parameters. The type of sensors used with the patient depends upon the patient's physical condition and the reasons for monitoring the patient's health.

Based upon the large number of different inputs that can be received by the patient monitor, patient monitors typically include separate input ports specifically designed to receive a certain type of sensor. As an example, pulse oximetry sensors are optical based sensors that provide a standard type of output signal that must be conditioned and amplified within the patient monitoring device. Conversely, other sensors, such as temperature sensors, include a thermistor that changes resistance based upon temperature. A temperature sensor typically receives a drive signal from the patient monitor and the output signal received by the patient monitor provides an indication of the temperature of the patient.

Since modern patient monitors can be used with a relatively large number of different types of sensors, the input panel to the patient monitor often includes a significant number of separate, specifically designed input ports. Since each of the input ports includes its own hardware interface circuit, the interface circuit hardware and separate input ports can increase both the cost and complexity of the patient monitor.

SUMMARY

The present disclosure relates to a method and system that allows different types of sensors to be connected to the same input port of a patient monitor. The system and method of the present disclosure includes circuits and components that allow a data acquisition module of the patient monitor to determine the type of sensor connected to the input port and, based upon the identified sensor type, configure the input port and signal conditioning circuitry to properly handle the sensor data.

The data acquisition module is designed for use with a patient monitor that receives and monitors physiological data obtained from one or more sensors connected to the patient. Various different types of physiological data can be obtained from the patient, such as but not limited to pressure, temperature and the cardiac output of the patient. The data acquisition module includes at least one multi-mode input port. Each of the multi-mode input ports can receive one of the plurality of different sensor types. When the sensor is received within the input port, the sensor can deliver and receive signals from the data acquisition module.

The data acquisition module farther includes an interface circuit that is coupled to the input port. The interface circuit is operable to selectively apply a default signal to the sensor when the sensor is initially connected to the input port. The interface circuit can include an adjustable voltage supply that initially applies the default signal to the sensor.

After the default signal is applied to the sensor, a processor positioned within the data acquisition module receives an output signal from the sensor. Based upon the received output signal, which is generated after application of the default signal, the processor can determine the type of sensor connected to the input port. Based upon the determined type of sensor, the processor generates a sensor identifier that is delivered to the patient monitor along with the conditioned output signal from the sensor.

The data acquisition module can further include a detection module that includes a plurality of amplifiers. When the data acquisition module determines the type of sensor connected to the input port, the detection module is configured to route the output signal from the sensor to one of a plurality of amplifiers to create an amplified output signal. The type of amplifier selected is based upon the type of sensor connected to the input port.

The interface circuit further includes an adjustable power supply that can be configured to apply both the default signal and a drive signal to each of the sensors. The processor of the data acquisition module selects the proper value for the drive signal based upon the determined type of sensor. In this manner, the data acquisition module is able to provide the required drive signal to each of the individual sensors.

DETAILED DESCRIPTION

FIG. 1illustrates a prior art patient monitor illustrating the complexity and cost associated with receiving physiological data from a large number of separate, individual sensors. As shown inFIG. 1, the patient monitor10includes a patient monitor controller12that operates the patient monitor display14and receives user input through an input device16. The input device can be one of many different types, including a keyboard, touch pad or a touch screen incorporated into the display14. The input device16allows a user to adjust various operating parameters of the patient monitor10and also to control the display14.

The patient monitor10includes a plurality of input ports18that are each configured to receive a specific type of sensor. Typically, the input ports18are labeled on the patient monitor with the type of sensor that should be connected to the input port. In the embodiment shown inFIG. 1, the input ports18are shown connected to a pressure sensor20, a temperature sensor22and a cardiac output sensor24. Since each of these three sensors20,22and24is a different type of sensor and provides a different output signal, the patient monitor10shown inFIG. 1includes three separate interface circuits26,27and28. As an illustrative example, the pressure sensor20typically takes the form of a resistive bridge transducer that is driven by a voltage input and generates a differential voltage output across a pair of resistors formed as part of a wheatstone bridge. The interface circuit26is designed to supply the proper drive voltage to the pressure sensor20while also receiving the differential voltage signal from the pressure sensor.

Temperature sensor22is typically a thermistor that is formed as part of a voltage divider. Once again, the interface circuit27is specifically configured to provide the required drive signal to the temperature sensor22and to receive the voltage output from the temperature sensor22, which is measured relative to ground potential.

The cardiac output sensor24is similar to the temperature sensor22and includes a variable resistor. The interface circuit28is specifically designed to provide a drive voltage to the cardiac output sensor24while receiving the voltage signal output from the cardiac output sensor, which is measured relative to ground potential. Since each of the three sensors20,22and24require a different drive signal and generate a different type of output signal, the three interface circuits26,27and28are included in the patient monitor and are specifically designed based upon the desired type of sensor connected to the respective input port18.

In the embodiment illustrated inFIG. 1, each of the interface circuits26,27and28provides the conditioned output signal from the sensor to an analog to digital converter31. Although three separate A/D converters31are shown inFIG. 1, the A/D converters could be combined and each receive an output signal from one of the interface circuits26,27or28.

The digitized output signal from the A/D converter31is provided to the patient monitor controller12. Since each of the input ports18receives a different type of sensor, the patient monitor controller12is able to condition the digitized output signal and provide the correct value for the physiological signal monitored from the patient.

As can be understood inFIG. 1, the patient monitor10required separate interface circuitry for each of the individual sensors connected to the patient monitor. Although this type of system provides the correct type of digitized data to the patient monitor controller12, the inclusion of the multiple interface circuit increases both the cost and complexity of the patient monitor.

FIG. 2illustrates a patient monitor30constructed in accordance with the present disclosure. The patient monitor30includes a display32driven by the patient monitoring controller34. The patient monitor30includes a data acquisition module36that includes a plurality of multi-mode input ports38. The multi-mode input ports38are configured to allow any one of a plurality of different types of sensors to be connected to the input ports38of the data acquisition module36. The data acquisition module36functions to initially identify the type of sensor connected to the input port38and, based upon the identified type of sensor, provides the required drive signal to the sensors. In addition, the data acquisition module36provides a sensor identifier along with a digitized output signal to the controller34such that the controller34can drive the display32. In the embodiment shown inFIG. 2, three different types of sensors40are positioned in contact with the patient42being monitored.

FIG. 3illustrates the patient monitor30including the data acquisition module36shown in greater detail. As illustrated inFIG. 3, the data acquisition module36includes three multi-mode input ports38that each can be connected to one of a series of individual sensors. In the embodiment shown inFIG. 3, pressure sensor20is connected to the first input port38, a temperature sensor22is connected to the second input port while a cardiac output sensor24is connected to the third input port38. Although three different types of sensors are shown in the embodiment ofFIG. 3, it should be understood that various other types of sensors could be utilized or less than three sensors utilized while operating within the scope of the present disclosure.

Although various different types of pressure sensors20can be utilized with the patient monitor, one example of a resistive bridge pressure sensor20is shown inFIG. 4. In the embodiment shown inFIG. 4, the pressure sensor20includes a resistive bridge network including four separate resistors44, at least two of which change in value depending upon the pressure exerted on the resistors. A drive voltage (Vinput) is supplied to the resistive bridge and a differential voltage is measured between points46and48. The differential voltage between points46and48is thus an indication of the pressure measured by the pressure sensor20. In the embodiment shown inFIG. 4, the differential voltage is applied to an amplifier50that generates an amplified output signal (Vout) at line53.

FIG. 5illustrates an exemplary embodiment of the temperature sensor22shown inFIG. 3. As illustrated inFIG. 5, the temperature sensor22includes a thermistor54that forms part of a voltage divider with another resistor56. An output signal from the temperature sensor22is available along line58. The output signal at line58is an absolute voltage signal that is measured between line58and ground60. The thermistor54receives a drive signal (Vinput) and generates an output signal on line58that varies based upon the value of the thermistor54.

The output signal on line58is fed into an amplifier62such that an amplified output signal (Vout) is available at point63.

Although two different types of sensors and amplifiers are illustrated inFIGS. 4 and 5, it should be understood that various different types of sensors and amplifiers could be utilized. The cardiac output sensor24shown inFIG. 3is similar to the temperature sensor22in that the cardiac output sensor24includes a variable resistor that is formed as part of a voltage divider. The amplifier62shown inFIG. 5could be used with the cardiac output sensor and the gain adjusted in a known manner.

Referring back toFIG. 3, each of the sensors20,22and24communicates to an interface circuit64through one of the respective multi-mode input ports38. The interface circuit64includes various configurable components, including an analog switching network and a variable voltage supply15that allows the interface circuit to both supply the desired drive signal to the connected sensors as well as to provide the output signal from the sensors to a detection module66. The detection module66includes a plurality of individual amplifiers and conditioning circuits, such as the amplifiers50and62shown inFIGS. 4 and 5.

As indicated above, the interface circuit64includes a variable voltage supply65that can supply the required drive signal to the sensors connected to any one of the three input ports38. The value of the voltage from the supply65is controlled by a processor included in the module36.

When any one of the sensors is initially connected to one of the input ports, the voltage supply65contained within the interface circuit64generates a default voltage signal to the sensor. The default signal is a known, defined voltage that is applied to the sensor. Based upon the default signal applied to the sensor, the sensor generates an output signal that is received at the interface circuit64. The output signal from the sensor then passes through a default amplifier contained within the detection module66and is received by the analog to digital converter68. The analog to digital converter68converts the analog output signal to a digital output signal, which is received by the processor70that is included in the data acquisition module36. Although the processor70is shown as a standalone component, it should be understood that the processor70could also be included within the detection module66.

The processor70includes a memory72that includes a plurality of stored sensor profiles. The stored sensor profiles are pre-determined, representative responses that represent the anticipated output signal that should be received within the processor70upon the application of the default signal by the voltage source in the interface circuit64to the respective sensor connected to the input port38. As an illustrative example, when the default signal is applied to the pressure sensor20shown inFIG. 4, the output signal received at the processor70will correspond to one of the sensor profiles. Based upon the comparison within the processor70, the data acquisition module36can determine the type of sensor connected to the input port38. The determined type of sensor is relayed to the patient monitor controller12through the communication line74as a sensor identifier. In addition, the digitized output signal from the sensor is conveyed to the patient monitor controller12through the output line76. In this manner, the patient monitor controller12is able to receive the digitized output signal as well as an indication of the sensor type. Based upon this information, the patient monitor controller12can operate the display14to properly display the physiological data received from the patient.

The processor70further communicates to the detection module66and, through a series of switches and digital register settings, controls the amplifier that is connected to the sensor at each of the input ports38. The specific amplifier is selected based upon the type of sensor connected to the input port. In addition, the processor70communicates to the interface circuit64, which allows the processor70to control the voltage drive signal supplied to each of the sensors. Additionally, the interface circuit can be configured to receive the specific output signal from the sensor. As discussed previously, the pressure sensor20includes a differential output signal while the temperature sensor22and the cardiac output sensor24include an absolute voltage signal relative to ground.

FIG. 6illustrates one example of the operational steps carried out by the system of the present disclosure to initially determine the type of sensor connected to the multi-mode input ports and, once the type of sensor is identified, provide the required drive signal to the sensor and connect the sensor to the required amplification circuit.

Initially, the sensor is connected to one of the multi-mode input ports, which in turn is connected to the interface circuit, as illustrated in step80. Once the sensor is coupled to the interface circuit through the input port, the data acquisition module generates a default drive signal to the sensor, as indicated in step82. As illustrated inFIG. 3, the processor70is in communication with the interface circuit64to indicate that the power supply65of the interface circuit64should generate the default drive signal, which is then received by the respective sensor20,22or24connected to the input port38. As described previously with respect toFIGS. 4 and 5, the default drive signal cause the sensor to generate an output signal which is received from the sensor in step84. The output signal received from the sensor in step84is based upon the default drive signal sent to the sensor by the interface circuit64. Since each of the individual sensors has different characteristics, the output signal received from the sensor is going to be dependent upon the physical characteristics of the sensor itself.

In step86, the processor70compares the returned output signal to known sensor profiles that are maintained in a memory72of the processor70. Once the type of sensor is identified, the processor70configures the interface circuit64to accept both the output signal from the sensor and to create the correct drive signal to the sensor, as illustrated in step88. In addition to configuring the interface circuit, the processor70sends a signal to the detection circuit66which manipulates a series of switches to insure that the proper amplifier is coupled to receive the output signal from the sensor, as shown in step90.

Once the drive signal and amplification circuit have been correctly coupled to the input port, the output signal from the sensor is fed through the analog to digital converter and ultimately received at the patient monitor controller. In addition to the amplified and digitized output signal, the processor70sends a sensor identifier to the patient monitor controller through the communication line74, as indicated in step92. Once the patient monitor controller receives both the sensor identifier and the output signal, the patient monitor controller can display the physiological data properly on the display unit14. As indicated in step94, the data acquisition module36continues to drive the sensor utilizing the identified proper drive signal.

As indicated above, the method and system of the present disclosure allows the patient monitor to include multiple input ports that can receive sensors of various different types. Once the sensor is attached to the patient monitor, the patient monitor identifies the sensor type and provides the required drive signal and conditioning circuit such that the output signal from the sensor is properly conditioned and supplied to the patient monitor controller. The multi-mode output port allows the patient monitor to include fewer output ports while still allowing for configuration with different types of sensors.