Patient monitoring system

Claim 2

A glucose monitoring system comprising: an enzymatic glucose sensor adapted to be placed within a person whose blood glucose concentration is to be measured, said glucose sensor including means for generating a sensor signal that varies inversely proportional to the concentration of sensed glucose, said glucose sensor comprising an oxygen detector that detects the amount of oxygen in the region of a prescribed enzyme held within said glucose sensor, and wherein glucose and oxygen react with said prescribed enzyme such that the amount of oxygen is inversely proportional to the glucose concentration, and wherein said oxygen detector comprises a first working electrode, a counter electrode, a reference electrode, and a second working electrode, all of said first and second working electrodes, reference electrode and counter electrode being enclosed within a first membrane wherein an ionic solution is maintained, and said first membrane being enclosed within a second membrane, said prescribed enzyme being confined to a window region near said first working electrode, electrical means for causing an electrical current to flow between said counter electrode and said first and second working electrodes, and means for measuring how much current flows from said first and second working electrodes when a prescribed trim voltage is maintained across said reference electrode and said first and second working electrodes; sensor signal comprises the ratio of said currents, thereby providing a measure of oxygen in the vicinity of said glucose sensor; and a glucose monitor electrically coupled to the glucose sensor, said monitor comprising means for receiving the sensor signal from the signal generating means, means for processing the sensor signal and generating a glucose concentration data signal therefrom, means for storing the glucose concentration data signal, means for monitoring the glucose concentration data signal over a prescribed period of time and generating a rate of change signal that indicates how rapidly the glucose concentration data signal is changing, means for selectively displaying the glucose concentration data signal and the rate of change signal, first alarm means for determining if the glucose concentration data signal exceeds a preset level limit, and if so, generating a first alarm signal, second alarm means for determining if the rate of change signal exceeds a preset trend limit, and if so, generating a second alarm signal, calibration means for periodically calibrating the sensor so that it provides an accurate measure of the glucose concentration in the blood stream, and control means for controlling the monitor so that it performs at least one of a plurality of monitoring functions as selected by a user of said monitor.

Claim 3

The glucose monitoring system as set forth in claim 1 wherein said prescribed enzyme comprises glucose oxidase.

Claim 4

The glucose monitoring system as set forth in claim 1 wherein said calibration means includes means for normalizing a ratio of said currents with a calibration constant, said calibration constant being obtained from an independent measure of the glucose concentration in a tissue/fluid sample taken from the patient.

Claim 5

The glucose monitoring system as set forth in claim 3 wherein said glucose monitor further includes means for issuing a calibration message in the event said independent measure of the glucose in the tissue/fluid sample has not been taken within a prescribed period from a prior calibration.

Claim 6

The glucose monitoring system as set forth in claim 3 wherein said calibration means further includes means for downloading calibration data to said glucose monitor at the time that a particular glucose sensor is first coupled to said glucose monitor, said calibration data being generated at the time of manufacture of said glucose sensor.

Claim 7

The glucose monitoring system as set forth in claim 1 wherein said glucose monitor includes a flat display of at least four inches by four inches overlaid with a touch sensitive screen, and wherein said control means comprises means for displaying one of a plurality of menus on said display, each of said plurality of menus including at least one button labeled with a monitoring function, and wherein said touch sensitive screen includes means for sensing if said display is touched by a user of said glucose monitor at a button of said menu, and if so, carrying out the function specified by said button.

Claim 8

The glucose monitoring system as set forth in claim 6 wherein said means for displaying further comprises at least one button for displaying the glucose concentration data signal in large numbers that substantially fill said flat display.

Claim 9

The glucose monitoring system as set forth in claim 1 wherein said glucose sensor is electrically coupled to said glucose monitor through a coupling cable that provides direct electrical contact between the glucose monitor and the glucose sensor.

Claim 10

The glucose monitoring system as set forth in claim 8 wherein said glucose sensor is coupled to said glucose monitor through a contactless coupling that electrically isolates said glucose sensor from said glucose monitor.

Claim 11

The glucose monitoring system as set forth in claim 9 wherein said contactless coupling comprises a transformer coupling.

Claim 12

The glucose monitoring system as set forth in claim 9 wherein said contactless coupling comprises an optical coupling.

Claim 13

The glucose monitoring system as set forth in claim 9 wherein said contactless coupling includes signal processing means on a sensor side of said coupling, said signal processing means including means for encoding the sensor signals passed through to the glucose monitor with sensor source information, whereby all of the sensor signals passed through to the glucose monitor may share a common set of cables.

Claim 14

The glucose monitoring system as set forth in claim 12 wherein said contactless coupling further includes a memory element having calibration data stored therein unique to said sensors, and a battery on the sensor side of said coupling, said battery providing a source of continuous power to said sensors.

Claim 15

The glucose monitoring system as set forth in claim 13 wherein said contactless coupling includes at least one magnet and a metal member to which said magnet is attracted, the magnet or metal member being located on the sensor side of the coupling, and the other of the magnet or metal member being located on a monitor side of the coupling, said magnet having a magnetic force field that pulls the magnet toward the metal member, said magnetic force field thereby holding said contactless coupling together.

Claim 16

A glucose monitoring system comprising: a glucose assembly comprising a plurality of glucose sensors, each glucose sensor comprising an enzymatic glucose sensor adapted to be positioned within a person whose glucose concentration is to be measured, each glucose sensor of the glucose assembly providing a respective sensor signal that varies as a function of sensed glucose; and a glucose monitor electrically coupled to the glucose assembly, said glucose monitor comprising means for receiving the sensor signal from each glucose sensor, means for processing the sensor signal received from each glucose sensor, said means for processing including means for comparing the sensor signals obtained from each of said plurality of sensors and generating a composite sensor signal only if the respective sensor signals are within a first prescribed amount of each other, means for storing the composite sensor signal, means for monitoring the composite sensor signal over a prescribed period of time and generating a rate of change signal that indicates how rapidly the composite sensor signal is changing, means for selectively displaying the composite sensor signal and the rate of change signal, first alarm means for determining if the composite sensor signal exceeds a preset level limit, and if so, generating a first alarm signal, second alarm means for determining if the rate of change signal exceeds a preset trend limit, and if so, generating a second alarm signal, calibration means for periodically verifying that each glucose sensor of the sensor assembly provides an accurate measure of the glucose concentration in the blood stream, and control means for controlling the monitor so that it performs at least one of a plurality of monitoring functions as selected by a user of said monitor.

Claim 17

A glucose monitoring system comprising: a glucose assembly comprising a plurality of glucose sensors, each glucose sensor comprising an enzymatic glucose sensor adapted to be positioned within a person whose glucose concentration is to be measured, each glucose sensor of the glucose assembly providing a respective sensor signal that varies as a function of sensed glucose; and a glucose monitor electrically coupled to the glucose assembly, said glucose monitor comprising means for receiving the sensor signal from each glucose sensor, means for processing the sensor signal received from each glucose sensor, said means for processing including means for comparing the sensor signals obtained from each of said plurality of sensors and generating a composite sensor signal only if the respective sensor signals are within a first prescribed amount of each other, means for storing the composite sensor signal, means for monitoring the composite sensor signal over a prescribed period of time and generating a rate of change signal that indicates how rapidly the composite sensor signal is changing, means for selectively displaying the composite sensor signal and the rate of change signal, first alarm means for determining if the composite sensor signal exceeds a preset level limit, and if so, generating a first alarm signal, second alarm means for determining if the rate of change signal exceeds a preset trend limit, and if so, generating a second alarm signal, calibration means for periodically verifying that each glucose sensor of the sensor assembly provides an accurate measure of the glucose concentration in the blood stream, and control means for controlling the monitor so that it performs at least one of a plurality of monitoring functions as selected by a user of said monitor.

Claim 18

The glucose monitoring system as set forth in claim 15 wherein said processing means further includes means for generating an error message in the event that the respective sensor signals are not within said first prescribed amount of each other, said error message advising a user of said glucose monitor to check said plurality of glucose sensors.

Claim 19

The glucose monitoring system as set forth in claim 16 wherein said processing means further includes shutdown means for automatically shutting down said glucose monitor in the event at least one of the sensor signals differs from the others of said sensor signals by more than a second prescribed amount.

Claim 20

The glucose monitoring system as set forth in claim 15 further including at least one additional sensor adapted to sense a parameter other than glucose concentration, and wherein said processing means includes means for combining all of the sensor signals in arriving at said composite sensor signal.

Claim 23

The method, as set forth in claim 19, wherein said glucose assembly is inserted into the peritoneal system of the patient.

Claim 24

The method, as set forth in claim 19, wherein said glucose assembly is placed in contact with body tissue of the patient.

Claim 25

A patient monitoring system comprising: an enzymatic sensor adapted to be inserted into a patient in order to make contact between said sensor and a bodily fluid/tissue of said patient, said sensor including means for generating a sensor signal that varies as a function of concentration of a substance sensed in said bodily fluid/tissue, said sensor comprising a detector that detects the amount of said substance in the region of a prescribed enzyme held within said sensor, and wherein said substance in said bodily fluid/tissue reacts with said prescribed enzyme such that the amount of said substance can be measured, and wherein said detector comprises a first working electrode, a counter electrode, a reference electrode, and a second working electrode, all of said first and second working electrodes, reference electrode and counter electrode being enclosed within a first membrane wherein an ionic solution is maintained, and said first membrane being enclosed within a second membrane, said prescribed enzyme being confined to a window region near said first working electrode, electrical means for causing an electrical current to flow between said counter electrode and said first and second working electrodes, and means for measuring how much current flows from said first and second working electrodes when a prescribed trim voltage is maintained across said reference electrode and said first and second working electrodes, said measuring means being in communication with said sensor signal generating means, the sensor signal comprising the ratio of said currents and being representative of the substance concentration in said bodily fluid/tissue in the vicinity of said sensor; and a monitor electrically coupled to the sensor, said monitor comprising means for receiving the sensor signal, means for processing the sensor signal and generating a substance concentration data signal therefrom, means for storing the substance concentration data signal, means for monitoring the substance concentration data signal over a prescribed period of time and generating a rate of change signal that indicates how rapidly the substance concentration data signal is changing, means for selectively displaying the substance concentration data signal and the rate of change signal, first alarm means for determining if the substance concentration data signal exceeds a preset level limit, and if so, generating a first alarm signal, second alarm means for determining if the rate of change signal exceeds a preset trend limit, and if so, generating a second alarm signal, calibration means for periodically calibrating the sensor so that it provides an accurate measure of the substance concentration in the bodily fluid/tissue, and control means for controlling the monitor so that it performs at least one of a plurality of monitoring functions as selected by a user of said monitor.

Claim 26

A patient monitoring system comprising: an enzymatic sensor adapted to be inserted into a patient in order to make contact between said sensor and a bodily fluid/tissue of said patient, said sensor including means for generating a sensor signal that varies as a function of concentration of a substance sensed in said bodily fluid/tissue, said sensor comprising a detector that detects the amount of said substance in the region of a prescribed enzyme held within said sensor, and wherein said substance in said bodily fluid/tissue reacts with said prescribed enzyme such that the amount of said substance can be measured, and wherein said detector comprises a first working electrode, a counter electrode, a reference electrode, and a second working electrode, all of said first and second working electrodes, reference electrode and counter electrode being enclosed within a first membrane wherein an ionic solution is maintained, and said first membrane being enclosed within a second membrane, said prescribed enzyme being confined to a window region near said first working electrode, electrical means for causing an electrical current to flow between said counter electrode and said first and second working electrodes, and means for measuring how much current flows from said first and second working electrodes when a prescribed trim voltage is maintained across said reference electrode and said first and second working electrodes, said measuring means being in communication with said sensor signal generating means, the sensor signal comprising the ratio of said currents and being representative of the substance concentration in said bodily fluid/tissue in the vicinity of said sensor; and a monitor electrically coupled to the sensor, said monitor comprising means for receiving the sensor signal, means for processing the sensor signal and generating a substance concentration data signal therefrom, means for storing the substance concentration data signal, means for monitoring the substance concentration data signal over a prescribed period of time and generating a rate of change signal that indicates how rapidly the substance concentration data signal is changing, means for selectively displaying the substance concentration data signal and the rate of change signal, first alarm means for determining if the substance concentration data signal exceeds a preset level limit, and if so, generating a first alarm signal, second alarm means for determining if the rate of change signal exceeds a preset trend limit, and if so, generating a second alarm signal, calibration means for periodically calibrating the sensor so that it provides an accurate measure of the substance concentration in the bodily fluid/tissue, and control means for controlling the monitor so that it performs at least one of a plurality of monitoring functions as selected by a user of said monitor.

Claim 29

The method of claim 23 further including: (a) storing the composite substance measurement as a function of time; (b) computing a rate-of-change signal for the composite substance measurement that indicates how said composite substance measurement has varied over a specified period of time; (c) comparing the composite substance measurement formed most recently and the rate-of-change signal to preprogrammed limits, and generating an alarm signal in the event the preprogrammed limits are exceeded; and (d) selectively displaying the composite substance measurement and rate-of-change signal.

Claim 30

An enzymatic sensor adapted to be inserted into a patient in order to make contact with body fluid/tissue of said patient, said sensor comprising: a first working electrode (W1), a counter electrode (C), a reference electrode (R), and a second working electrode (W2), all of said first and second working electrodes, reference electrode and counter electrode being enclosed within a first membrane wherein an ionic solution is maintained, and said first membrane being enclosed within a second membrane, said prescribed enzyme being confined to a window region near said first working electrode, electrical means for causing an electrical current to flow between said counter electrode and said first and second working electrodes, and means for measuring how much current flows from said first and second working electrodes when a prescribed trim voltage is maintained across said reference electrode and said first and second working electrodes, a ratio of said currents comprising a sensor signal, which sensor signal provides a measure of the substance concentration in said body fluid/tissue in the vicinity of said sensor.

Claim 31

An enzymatic sensor adapted to be inserted into a patient in order to make contact with body fluid/tissue of said patient, said sensor comprising: a first working electrode (W1), a counter electrode (C), a reference electrode (R), and a second working electrode (W2), all of said first and second working electrodes, reference electrode and counter electrode being enclosed within a first membrane wherein an ionic solution is maintained, and said first membrane being enclosed within a second membrane, said prescribed enzyme being confined to a window region near said first working electrode, electrical means for causing an electrical current to flow between said counter electrode and said first and second working electrodes, and means for measuring how much current flows from said first and second working electrodes when a prescribed trim voltage is maintained across said reference electrode and said first and second working electrodes, a ratio of said currents comprising a sensor signal, which sensor signal provides a measure of the substance concentration in said body fluid/tissue in the vicinity of said sensor.

Claim 32

A sensor assembly adapted for implantation into the body of a patient to measure the concentration of one or more substances in the patient's blood, said sensor assembly comprising: a substrate; first and second sets of sensors spaced apart on said substrate, wherein each set of sensors comprises: first and second working electrodes bonded to said substrate; a reference electrode bonded to said substrate; a counter electrode bonded to said substrate; and means for making electrical contact with said first and second working electrodes, reference electrode, and counter electrode; a layer of insulation deposited on said substrate and means for making electrical contact so as to be interspersed between the electrodes bonded to said substrate, a prescribed surface area of each of said electrodes being exposed through said layer of insulation, whereby said first and second working electrodes, reference electrode and counter electrode are all electrically isolated from each other on said substrate; first membrane means covering said substrate and electrodes; a saline solution held within said first membrane, said saline solution being in contact with said electrodes bonded to said substrate; second membrane means covering said first membrane means, said second membrane means having a window pocket therein above the exposed surface area of said first working electrode; a prescribed enzyme placed within said window pocket; and means for applying a prescribed reference voltage, within each set of sensors, between said counter electrode and said reference electrode, and between said first and second working electrodes and said reference electrode, and for measuring the electrical current that flows from said first and second working electrodes, within each set of sensors; whereby when said sensor assembly is inserted in the patient's venous system, oxygen and other substances in the blood of the patient may penetrate said first and second membrane means of each set of sensors and electrochemically react, in the presence of the prescribed enzyme held in said window pocket of each set of sensors, with the current flowing through each of said first working electrodes, and electrochemically react in the absence of said enzyme with the current flowing through each of said second working electrodes; said currents flowing through said first and second working electrodes of each set of sensors thereby providing a measure of oxygen and other substances in the blood of the patient as a function of the electrochemical reactions that occur at said first and second working electrodes of each set of sensors.

Claim 33

A sensor assembly adapted for implantation into the body of a patient to measure the concentration of one or more substances in the patient's blood, said sensor assembly comprising: a substrate; first and second sets of sensors spaced apart on said substrate, wherein each set of sensors comprises: first and second working electrodes bonded to said substrate; a reference electrode bonded to said substrate; a counter electrode bonded to said substrate; and means for making electrical contact with said first and second working electrodes, reference electrode, and counter electrode; a layer of insulation deposited on said substrate and means for making electrical contact so as to be interspersed between the electrodes bonded to said substrate, a prescribed surface area of each of said electrodes being exposed through said layer of insulation, whereby said first and second working electrodes, reference electrode and counter electrode are all electrically isolated from each other on said substrate; first membrane means covering said substrate and electrodes; a saline solution held within said first membrane, said saline solution being in contact with said electrodes bonded to said substrate; second membrane means covering said first membrane means, said second membrane means having a window pocket therein above the exposed surface area of said first working electrode; a prescribed enzyme placed within said window pocket; and means for applying a prescribed reference voltage, within each set of sensors, between said counter electrode and said reference electrode, and between said first and second working electrodes and said reference electrode, and for measuring the electrical current that flows from said first and second working electrodes, within each set of sensors; whereby when said sensor assembly is inserted in the patient's venous system, oxygen and other substances in the blood of the patient may penetrate said first and second membrane means of each set of sensors and electrochemically react, in the presence of the prescribed enzyme held in said window pocket of each set of sensors, with the current flowing through each of said first working electrodes, and electrochemically react in the absence of said enzyme with the current flowing through each of said second working electrodes; said currents flowing through said first and second working electrodes of each set of sensors thereby providing a measure of oxygen and other substances in the blood of the patient as a function of the electrochemical reactions that occur at said first and second working electrodes of each set of sensors.

Claim 34

The sensor assembly as set forth in claim 26 wherein said prescribed enzyme comprises glucose oxidase.

Claim 35

The sensor assembly as set forth in claim 26, wherein said first and second sets of sensors are separated on said substrate such that the window pockets are spaced apart about 0.4 to 1.0 inches along the length of the substrate.

Claim 36

The sensor assembly as set forth in claim 26 wherein said first and second sets of sensors further comprise a temperature sensor mounted on said substrate.

Claim 37

The sensor assembly as set forth in claim 29 wherein each of said temperature sensors comprises a prescribed semiconductor having a resistivity that varies as a function of temperature, and means for applying a voltage across said semiconductor, whereby the current flowing through said semiconductor provides a measure of the resistivity, and hence the temperature.

Claim 38

The sensor assembly as set forth in claim 29 further including a cable carrying sufficient electrical conductors to make contact with said first and second electrodes, reference electrode, counter electrode and temperature sensor of each of said sets of sensors, said cable terminating in a first contactless connector, said first contactless connector having a battery and a control chip therein that receives and processes the electrical current that flows from the first and second working electrodes of each set of sensors, said control chip including memory means for storing calibration data associated with said sensor assembly, processing means for processing the received electrical current with the calibration data to produce encoded sensor data signals, and transmitting means for transmitting the encoded sensor data signals to a receiver located in a second contactless connector, said second contactless connector being adapted to be coupled to said first contactless connector without making direct electrical contact therewith, whereby electrical isolation is provided between the first and second contactless connectors, said second contactless connector being coupled to a monitoring device whereat said encoded sensor data signals are decoded, displayed and stored.

Claim 39

The sensor assembly as set forth in claim 31 wherein said second contactless connector is coupled to said monitoring device through a connection cable having two electrical conductors.

Claim 40

The sensor assembly as set forth in claim 31 wherein at least one of said first and second contactless connectors includes a permanent magnet that is attracted to a metallic member in the other contactless connector, and wherein said permanent magnet provides a holding force for maintaining said first and second contactless connectors in close proximity to each other.