WO2014163815A1

WO2014163815A1 - Analyte sensing system with access port for alternative analyte measurement

Info

Publication number: WO2014163815A1
Application number: PCT/US2014/017258
Authority: WO
Inventors: Yaron Keidar
Original assignee: Edwards Lifesciences Corporation
Priority date: 2013-03-12
Filing date: 2014-02-20
Publication date: 2014-10-09

Abstract

Systems and methods are provided for performing an alternate blood concentration measurement of a subject's blood via an intravascular blood analyte monitoring system. The system includes a sampling line located in a subject's vasculature and an analyte sensor in fluid communication with the sampling line for receiving a blood sample and performing a blood analyte measurement. The system also includes an access port located in fluid communication with the sampling line. The access port is configured for receiving at least a portion of the blood sample receiving end of an analyte test strip. Using the test strip, a user may determine an analyte concentration of the subject's blood. The user may also use the analyte sensor to determine an analyte concentration of subject's blood. These two analyte concentration measurements can be used to calibrate the analyte sensor or to compensate subsequent analyte concentration values determined from samples of the subject's blood using analyte test strips.

Description

ANALYTE SENSING SYSTEM WITH ACCESS PORT FOR

ALTERNATIVE ANALYTE MEASUREMENT

TECHNICAL FIELD

[0001] An intravascular blood analyte monitoring system for sampling blood from a subject and performing an analyte concentration measurement of the blood, wherein such system further comprises an access port in fluid communication with the vasculature of a subject for alternative analyte measurement.

BACKGROUND

[0002] Analyte monitoring systems have been developed for in vivo measurement of a concentration of an analyte in a fluid. As an example, analyte monitoring systems have been developed for vasculature insertion in a subject so as to sample analytes, such as glucose, in a subject's blood. The system is essentially a "closed loop" system. It draws blood samples from the patent passed an analyte sensor for measurement. The blood sample is typically then returned to the subject's body so as to avoid blood waste, exposure by others to the subject's blood, and reducing exposure to infection.

[0003] Some analyte monitoring systems use a cyclical calibration/sample measurement/calibration cycle. The system first infuses calibration solution over a sensor assembly to calibrate the sensor. The system next draws a sample to the sensor assembly for analyte measurement of the sample. The system then recalibrates the sensor by infusing calibrant again past the sensor for purposes of calibration. In continuous analyte monitoring, a sensor may be repeatedly used over a series of hours or days to report sensed analyte parameters.

[0004] Generally, to initially calibrate the analyte monitoring system, a blood sample is initially drawn from the subject and provided to a lab for measurement of analyte concentration. For example, where the analyte monitoring system is used to measure glucose concentration, an initial blood sample is drawn from the subject and provided to the lab to determine the glucose concentration of the subject's blood. The lab results are then inputted to the analyte monitoring system as a reference value for initial calibration. In some configurations, periodic updated lab results (such as every 72 hours) from subsequent subject blood samples may be used as independent reference calibration points for recalibration of the analyte monitoring system.

[0005] There may also be instances where a caregiver may wish to perform a confirmatory glucose reading using an alternate system of glucose measurement, such as a glucose meter with a glucose test strip, or other portable system. Many hospitals have access to glucose meters designed for finger sticks capillary blood. In subjects with access to arterial blood or venous blood, typically a sample of that blood is taken with a syringe and dropped on a conventional glucose strip and glucose is determined using a conventional glucose meter. Manipulation of a syringe for this purpose is undesirable, inconvenient, and requires disposal of both the syringe and the test strip.

SUMMARY

[0006] Systems and methods are provided for performing an alternate blood concentration measurement of a subject's blood via an intravascular blood analyte monitoring system. The system includes a sampling line located in a subject's vasculature and an analyte sensor in fluid communication with the sampling line for receiving a blood sample and performing a blood analyte measurement. The system also includes an access port located in fluid communication with the sampling line. The access port is configured for receiving at least a portion of the blood sample receiving end of an analyte test strip. Using the test strip, a user may determine an analyte concentration of the subject's blood. The user may also use the analyte sensor of the intravascular blood analyte monitoring system to determine an analyte concentration of subject's blood. These two analyte concentration measurements can be used to calibrate the analyte sensor or to compensate subsequent analyte concentration values determined from samples of the subject's blood using analyte test strips.

[0007] In one embodiment, an intravascular blood analyte monitoring system is provided for measuring analytes in a blood sample from a subject. The system comprises a sampling line comprising a first end configured for location in the vasculature of a subject and an analyte sensor in fluid communication with the first end of the sampling line. A flow controller is in fluid communication with a second end of the sampling line for controlling the flow of blood to and from the subject for contacting the analyte sensor with blood from the subject. The system further comprises a first access port located between the first end of the sampling line and the flow controller. The first access port is configured for: 1) fluid communication with the sampling line; 2) receiving a sample receiving end of an analyte test strip; and 3) introducing a blood sample from the subject to the sample receiving end of the analyte test strip for analyte measurement. In some embodiments, the system may further comprise a vacuum device positioned in fluid communication with the first access port and at a location such that the first access port is located between the vacuum device and the first end of the sampling line. In an alternative or added embodiment, the system may include a second access port at a location such that the first access port is located between the second access port and the first end of the sampling line. The second access port is configured to couple with or receive a vacuum device, such as a syringe. In either embodiment, the vacuum device is configured to draw blood from the subject via the sampling line and configured to place a sample of the subject's blood in the presence of the first access port, such that the sample of the blood is accessible by accessing the first access port.

[0008] In some embodiments, the system further comprises a valve positioned between the vacuum device or second access port and the first access port. The valve can be manipulated to maintain a vacuum in the sampling line following a blood draw, so that blood can be accessed at the first access port.

[0009] In some embodiments, the first access port is configured to receive an analyte test strip. The first access port comprises a septum comprising an aperture having at least one in the range of 5 to 10 millimeters for receiving at least a portion of a sample receiving end of an analyte test strip. The septum may have an aperture having at least one dimension greater than or equal to 6 millimeters for receiving a sample receiving end of an analyte test strip. The aperture may be resealable in some embodiments and formed of one of a latex, silicone, urethane, and synthetic rubber material.

[0010] In embodiments including a second access port, the second access port may include a septum and an aperture, where the second access port aperture is configured to receive the needle of a syringe and has at least one dimension in the range of 0.1 to 5 millimeters. In some embodiments, the second access port may comprise a luer for connecting with a syringe.

[0011] The present invention also provides a method for measuring an analyte in a subject's blood. The method comprises providing an intravascular blood analyte monitoring system comprising a sampling line comprising a first end configured for location in the vasculature of a subject, an analyte sensor located in and adjacent to the first end of the sampling line, a flow controller in fluid communication with a second end of the sampling line for controlling the flow of blood to and from the subject for contacting the analyte sensor with blood from the subject, and a first access port located between the analyte sensor and the flow controller, the first access port configured for receiving at least a portion of a sample receiving end of an analyte test strip. The method comprises inserting at least a portion of the sample receiving end of the analyte test strip into the first access port to expose the sample receiving end of the analyte test strip to the subject's blood and determining a blood analyte concentration of the subject's blood using the analyte test strip.

[0012] In some embodiments, the method further comprises determining a blood analyte concentration of the subject's blood using the analyte sensor. The method may further comprise determining an offset value representing a difference between an analyte concentrations determined from the analyte test strip and an analyte concentration determined from the analyte sensor. The offset value may be used to calibrate the analyte sensor and/or to compensate subsequent analyte concentration values determined from samples of the subject's blood using analyte test strips.

[0013] In some embodiments, the method further comprises applying a vacuum pressure at a location upstream from the first access port and the first end of the sampling line so as to draw blood from the subject to the location of the first access port. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Having thus described embodiments of the system in general terms, reference will now be made to the accompanying drawings, where:

[0015] FIG. 1 is a perspective view of an analyte sensing system of one embodiment of the present disclosure;

[0016] FIG. 2 is an operational diagram of the analyte sensing system of FIG. 1 ;

[0017] FIG. 3 is perspective view of the sensor assembly of FIG. 1 according to one embodiment;

[0018] FIG. 4 is a schematic of a rotary pinch valve of a flow control system according to an embodiment of the present disclosure;

[0019] FIG. 5 is a fluid flow profile diagram used in one example with the flow control system of FIG. 4;

[0020] FIG. 6 is an operational flow diagram of flow control cycle for a first measurement cycle according one embodiment of the present invention;

[0021] FIG. 7 is a perspective view of an analyte monitoring system comprising an alternative access port for sampling a subject's blood;

[0022] FIGs. 8A and 8B are cross-section al views of an access port according to one embodiment of the present invention;

[0023] FIG. 9 is a perspective view of an analyte monitoring system comprising an alternative access port for sampling a subject's blood according to another embodiment of the present invention. ;

[0024] FIG. 10 is a perspective view of an alternative embodiment of the system depicting in FIG. 9; and

[0025] FIG. 11 is perspective view of the analyte monitoring system comprising an alternative access port for sampling a subject's blood depicted in FIG. 9 illustrating use of the system. DET AILED DESCRIPTION

[0026] Embodiments of the present system and methods now may be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the system are shown. Indeed, the system and methods may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure may satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0027] As used in the specification, and in the appended claims, the singular forms

"a", "an", "the", include plural referents unless the context clearly dictates otherwise. The term "comprising" and variations thereof as used herein is used synonymously with the term "including" and variations thereof and are open, non-limiting terms.

[0028] Blood, as used herein, should be construed broadly to include any body fluid with a tendency to occlude lumens of various body-access devices during sampling. The body access devices include blood access devices such as catheters, tubes, and stents.

[0029] Systems and methods are provided herein for allowing access to blood samples from a subject via an intravascular blood analyte monitoring system, such that an alternative analyte concentration measure of the blood may be made. Generally, the system of the present invention includes an access port in fluid communication with a sampling line of the analyte monitoring system. The access port is configured to receive a test sampling end of an analyte test strip and place the analyte test strip in contact with subject blood in the sampling line. In this manner, a measurement of an analyte concentration in the blood can be determined via analysis of the analyte test strip. The analyte concentration determined from analysis of the analyte test strip may be used as an independent determination of the analyte concentration of the subject's blood. The determined analyte concentration from analysis of the analyte test strip may also be compared to an analyte concentration reading from the analyte sensor of the analyte monitoring system to create an offset value. The offset value may be used to calibrate the analyte sensor or to compensate subsequent analyte concentration values determined from samples of the subject's blood using analyte test strips. [0030] Representative Analyte Monitoring System

[0031] The present invention can be used in conjunction with existing intravascular blood analyte systems. Provided below is a brief description of a general blood analyte system in which the current invention may be incorporated. This description is provided for example purposes and should not limit the scope of the invention. The invention may be used with any blood analyte monitoring system having access to subject blood.

[0032] With reference to FTGs. 1 and 2, a blood analyte monitoring system 10 includes a monitor 12, a sensor assembly 14, a calibrant solution source 32 and a flow control system 18. The system may also include other sensors, such as pressure sensors, temperature sensors, pH sensors, and the like. With reference to FTGs. 1 and 2, the flow control system 18 includes a flow controller 20, a sampling line 22, a sensor assembly 14, a sampling line 22 and a vascular access device 19. Generally, the flow control system 18 is configured to mediate flow of small volumes of the calibrant solution over a sensor 24 in the sensor assembly 14 and withdraw small volumes of samples of the blood from the subject for testing by the sensor 24.

[0033] FIG. 3 illustrates a perspective view of the sensor assembly 14. The sensor assembly comprises a first electronic housing or subassembly 26a for housing the sensor 24, not shown. In this depiction, a protective cap 28 with an associated luer 30 houses the sensor. The leads of the sensor are located in the first electronic housing subassembly 26a where they are connected to an electronics connection board. In the first electronic housing subassembly 26a, the leads of the sensor are segregated from the sampling line for connection to the monitor 12. Connected to the first electronic housing subassembly 26a is a multi-lumen sampling line 33 comprising separate lumens for communication lines or wires 36 and sampling tubing containing calibrant solution. The multi-lumen sampling line 33 is connected at an opposed end to a second electronic housing subassembly 26b, where the communication lines are again separated at a wire mount 34 for extension to the monitor 12 of FIG. 1.

[0034] As illustrated in FIG. 1, the monitor 12 is connected in communication with the sensor assembly 14 through the communication lines 36, which may be wires, and to the flow control system 18 through communication wires or lines 38. In an embodiment, the monitor and the flow controller are integrated together. The communication lines 36, 38 could also represent wireless data communication such as cellular, RF, infrared or blue- tooth communication. Regardless, the monitor 12 includes some combination of hardware, software and/or firmware configured to record and display data reported by the sensor assembly 14. For example, the monitor may include processing and electronic storage for tracking and reporting concentrations of an analyte in the subject's blood, such as blood glucose levels. In addition, the monitor 12 may be configured for automated control of various operations of other aspects of the blood analyte monitoring system 10. For example, the monitor 12 may be configured to operate the flow control system 18 to flush the sensor assembly 14 with a flush solution (e.g., saline) or a calibration solution 16 from calibrant solution source 32 and/or to draw samples of blood for testing by the sensor assembly. Also, the monitor 12 can be configured to calibrate the sensor 24 based on the flush cycle.

[0042] In some embodiments, the analyte sensor is configured to reside within the catheter lumen. In some embodiments, the sensor is disposed within the catheter such that the sensor does not protrude from the catheter orifice. In other embodiments, the sensor is disposed within the catheter such that at least a portion of the sensor protrudes from the catheter orifice. In still other embodiments, the sensor is configured to move between protruding and non-protruding configurations. The analyte sensor and vascular access device used in the blood analyte monitoring system 10 can be any types known in the art. For convenience, the vascular access device 19 will be referred to as a catheter herein. However, one skilled in the art appreciates that other vascular access devices can be used in place of a catheter.

[0043] In some embodiments, at least one electronics module (not shown) is included in the monitor 12, for controlling execution of various system functions, such as but not limited to system initiation, sensor calibration, operation of the flow controller 20 from one position to another, collecting and/or analyzing data, and the like. In other embodiments, the components and functions of the electronics module can be divided into two or more parts, such as between the local analyzer and remote analyzer. The monitor can be configured to accept digital and/or analog signals, as needed or desired. The components of the system 10 can be all solid state, for example.

[0044] While any number of flow controller configurations can be employed, for convenience of describing various aspects of the present disclosure, the flow controller 20 includes one or more valves and is configured to control fluid delivery to the subject and sample take-up (e.g., drawing blood back into the catheter and presenting flush and/or calibrant solution until at least the sensor's electroactive surfaces are contacted by the blood). With reference to FIG. 4, in one exemplary embodiment, the flow controller 20 is a rotating pinch valve that has first and second positions. The valve can move between the two positions, for example, backward and forward, and thereby move fluids in and out of the catheter. In this manner, with reference to FIGs. 1 and 2, solution 16 can be moved from the calibrant source 32, over electroactive surfaces of the sensor 24 and into the subject; and sample can be drawn up from the subject, to cover the electroactive surfaces of the sensor 24, and then infused into the subject, by movement of the valve between the first and second positions.

[0045] In some embodiments, the sensor 24 and one or all of the working electrodes, reference and/or counter electrodes, dwells within the lumen of the catheter 12. In one aspect, an internal calibration is performed where an infusion fluid (e.g., calibration solution 16) flows over the indwelling sensor 24 and is infused into the subject. Generally, analyte in the calibration solution 16 can be measured when the sensor electroactive surfaces are in contact with the calibration solution 16. In some embodiments, the measurements of the calibration solution 16 can be used to calibrate the sensor 24. After calibration, the system is configured such that a sample (e.g., blood or other bodily fluid) contacts the sensor's electroactive surfaces (e.g., by drawing blood back into the catheter). When the sample contacts the electroactive surfaces, the sample's analyte concentration can be detected by the sensor 24. When a sample is drawn back, the sample can then be returned to the subject via infusion.

[0046] In some embodiments, the blood analyte monitoring system 10 cycles between calibration (e.g., measurement of a reference calibration solution) and measurement (e.g., of a sample, such as blood, glucose concentration). In some embodiments, the system 10 continues operation in this cyclical manner, until the system 10 is either disconnected from the subject or turned off for a period of time (e.g., during movement of the subject from one location to another). For example, in one embodiment, the system 10 cycles between the calibration and measurement steps from about every 30 seconds or less to about every 2 hours or more. In another embodiment, the system 10 cycles between the calibration and measurement steps of from about every 2 minutes to about every 45 minutes. In still another embodiment, the system 10 cycles between the calibration and measurement steps from about every 1 minute to about every 10 minutes. In some embodiments, the user can adjust the time between steps. In some embodiments, the user can adjust the time between each step. In some embodiments, the system 10 can perform additional steps, such as but not limited to a flushing step, a keep vein open step (KVO), an extended infusion step, and the like. In some embodiments, the time is dependent upon sensors that detect a reference solution (e.g., calibration solution) and/or sample (e.g., blood) at the electroactive surfaces.

[0047] With reference to FIG. 2, a variety of flow regulators 17 can be used with the preferred embodiments, including but not limited to pinch valves, such as rotating pinch valves and linear pinch valves, cams and the like. In one exemplary embodiment, the flow regulator 17 is a pinch valve, supplied with one or more IV sets and located on the sampling line 22 adjacent to and below the drip chamber. In some embodiments, a flow regulator 17 controls the flow rate from the calibrant solution source 32 to a flow controller 20. In some embodiments, a flow regulator is optional; and a flow controller 20 controls the flow rate (e.g., from the calibrant solution source 32 to the catheter 19).

[0048] As discussed previously, in one embodiment, a flow profile is employed that cycles between calibration of the sensor and analyte measurement of blood samples. The cycle is continuous; alternating between infuse of calibrant past the sensor for calibration, followed by a blood draw for analyte sampling. In this embodiment of the flow profile, time between receipt of analyte sampling data is delayed due to the intermittent calibration portion.

[0049] FIG. 5 illustrates a flow profile according to one embodiment. The flow profile includes a calibration, draw, and flush phase. The flow profile can be of about 100 to about 500 seconds which includes a calibration flow rate of about 0.5 to about 10 mL/hr, a flush rate of about 200 to about 1000 mL/hr and trailing rates of about 0.1 to 10 mL/hr and essentially no zero flow. FIG. 5 illustrates only one example of a flow profile that could be used with the current invention. The flow profile could be continuous or include stagnant periods.

[0050] FIG. 6 is an operational flow diagram illustrating a calibrant, then sample flow control cycle and measurement. In an initial step, the flow controller infuses calibrant past the sensor. (See step 200). Calibration is performed on the sensor in the presence of the calibrant solution with known concentration. (See step 202). Following calibration, the flow controller draws blood from the subject and passed the sensor. (See step 204). In the presence of the blood sample, an analyte measurement of the blood is determined. (See step 206). The flow controller then infuses either a separate flush solution or the calibrant solution past the sensor again to repeat the cycle. (See step 208).

[0051] Blood Sample Access Port for Alternate Analyte Measurement

[0052] As mentioned, during an initial calibration phase of the intravascular analyte monitoring system, a blood sample is typically drawn from the subject and provided to a lab to determine an analyte concentration in the blood. This measured analyte concentration value is then provided to the intravascular analyte monitoring system to calibrate the analyte sensor. Periodically, such as, for example, every 72 hours, additional blood samples may be taken, analyzed by a lab, and the results entered into the analyte monitoring system for updates of calibration. In the interim, the use of the calibrant solution 16 in the calibrant source 32, as shown in FIGs. 1 and 2, is used to more frequently and/or intermittently maintain or provide calibration of the intravascular analyte monitoring system's analyte sensor.

[0053] Providing an independent assessment of an analyte concentration reading may be advantageous throughout the monitoring process. For example, obtaining and/or waiting for receipt of lab results may be non-preferred in some instances. While a user or caregiver could perform a finger stick to access subject blood for independent assessment, such invasive actions are also not likely preferred, and if taken from extremities (finger), may not accurately represent the vascular blood analyte concentrations. As an alternative, the systems and methods of the present invention provide for convenient access to the subject's blood without requiring the user or caregiver to create a new blood access beyond that currently provided by the indwelling analyte monitoring system.

[0054] With reference to FIGs. 1, 2, and 7, the system according to one embodiment of the present invention may include an alternative access device 40 for obtaining a blood sample from the subject. The alternative access device, in some embodiments, may comprise only a first access port 42 located in fluid communication with the sampling line 22 of the blood analyte monitoring system 10. FIG. 7 illustrates the first access port coupled to an end of the second electronic housing subassembly 26b and in fluid communication with the sampling line 22. It is understood, that FIG. 7 only discloses one example of placement of the first access port 42. The first access port 42 can be placed at any location relative to the blood analyte monitoring system 10, as long as it is in fluid communication with the sampling line 22. For example, the first access port could be located in the first electronic housing subassembly 26a, the second electronic housing subassembly 26b, or the multi-lumen sampling line 33.

[0055] As shown in FIGs. 8 A and 8B, the first access port 42 is essentially a resealable valve that allows access to fluid within the access port. FIGs. 8A and 8B depict orthogonal cross-sections of either the first access port 42 or the second access port 48. The first access port 42 comprises a hollow bore 43 comprising a sealing septum 44 having a resealable aperture 46 through which fluid within the first access port 42 can be accessed. In this regard, the sealing septum 44 may have a first portion and a second portion with an aperture (e.g., slit) therebetween. The first portion and the second portion typically join to form a mechanical seal to prevent leakage through the aperture 46. The septum can be formed of a latex, silicone, urethane, or synthetic rubber material. Alternately, the septum can be formed of a thermoplastic elastomer. The material used for the septum preferably is non-toxic and sterilizable such as by means of radiation, steam, or Ethylene Oxide.

[0056] As will be described later, the first access port 42 is configured to receive at least a portion of a sample receiving end of an analyte test strip. The dimensions of the hollow bore, septum, and aperture are sized to receive the test strip. For example, in one embodiment, the aperture has at least one dimension in the range of 5 to 10 millimeters for receiving a sample receiving end of an analyte test strip. And, in some embodiments, the dimension is greater than or equal to 6 millimeters for receiving a sample receiving end of an analyte test strip. In some embodiments, the septum may not include an aperture but may be merely puncturable by a portion of the strip, for example, a wicking portion of the strip. In this instance, the septum would have at least one dimension in the range of 5 to 10 millimeters for receiving a sample receiving end of an analyte test strip. And, in some embodiments, the dimension is greater than or equal to 6 millimeters for receiving a sample receiving end of an analyte test strip. Any commercially available strip can be adapted to the present device and methods. In one aspect, a low volume (e.g., microliter or sub-microliter or nanoliter), wicking-type analyte strip is used in conjunction with a low- volume access port to minimize the amount and duration of the blood need for the analyte strip. In other aspects, a custom strip or portions of a commercial strip are customized for the instant device and method. Thus, the depth of penetration of the portion of the strip can be very shallow (e.g., microns or millimeters).

[0057] In this embodiment, the first access port 42 allows a user or caregiver to obtain a sample of the subject's blood for analyte concentration measurement. For example, the flow controller 20 of the blood analyte monitoring system 10 can be controlled to draw a blood sample from the subject via the sampling line 22 such that blood is present at the first access port 42. A sample test end of an analyte strip could then be introduced through the first access port 42 and in contact with the subject's blood. Test strip may then be used in conjunction with an analyte meter to determine a concentration of an analyte in the blood, such as a blood glucose concentration.

[0058] As mentioned, the flow controller 20 of the blood analyte monitoring system 10 can provide a vacuum for drawing blood to the first access port 42. In some embodiments, the monitor 12 may include a flow control profile that can be selected by the user or caregiver. In this instance, the flow controller could be directed to provide a proper draw of blood to the first access port. In this regard, as mentioned, the first access port 42 could be located anywhere within the blood analyte monitoring system 10. In some embodiments, such as where the first access port 42 is located in the second electronic housing subassembly 26b, the sampling from the first access port 42 could be timed with the normal blood draw phase of the flow control cycle used by the flow controller in placing the analyte sensor 24 in the presence of a blood sample. [0059] In some embodiments, it may be desired to use a separate device for creating a vacuum blood sample draw. Referring again to FIG. 7, in one embodiment, the alternative access device 40 may comprise a second access port 48. The second access port 48 positioned in fluid communication with the first access port 42 and at a location such that the first access port 42 is located between the second access port 48 and the first end of the sampling line. The positioning of the first and second access port may be described also in terms of blood sample flow. The second access port 48 is positioned so that a vacuum device can be connected thereto and draw a blood sample from the subject and direct the blood sample to the first access port 42. The second access port 48 is thus considered upstream of the first end of the sampling line and upstream of the first access port 42.

[0060] As mentioned, the second access port 48 is provided for connecting a vacuum device to the sampling line fluid flow to apply a vacuum, and possibly, a flush in the sampling line to provide a draw of blood to the first access port 42. As an example, in one embodiment, the vacuum device may be a syringe. In this embodiment, the second access port 48 may be similar to the first access port 42, in that it comprises a septum comprising an aperture having at least one dimension in the range of 0.1 to 5 millimeters for receiving a syringe needle. The second access port 48 comprises a hollow bore comprising a sealing septum having a resealable aperture through which access to fluid within the second access port can be accessed. The septum can be formed of a latex, silicone, urethane, or synthetic rubber material. Alternately, the septum can be formed of a thermoplastic elastomer. The material used for the septum preferably is non-toxic and sterilizable such as by means of alcohol swabbing, peroxide vapor, radiation, steam, UV, or Ethylene Oxide. As with the first access port, in some embodiments, the second access port may not include an aperture in the septum. The septum could be puncturable, in which case the septum would have a dimension in the range of 0.1 to 5 millimeters for receiving a syringe needle. In some embodiments, the second access port comprises a luer 47 for connecting the second access port to a syringe or other form of vacuum device. In some embodiments, the vacuum device could be a pump or rotating valve structure for creating a vacuum. [0061] In some embodiments, the second access port may not include a puncturable septum or septum with a puncturable aperture. Instead, it could include some movable valve that can be displaced in order to apply a vacuum.

[0062] FIG. 9 depicts an alternative embodiment to that of FIG. 7. In this embodiment, a vacuum device is integrated into the alternative access device 40. In this embodiment, alternative access device 40 may include a vacuum device 50. The vacuum device could be any form of pump or vacuum. The vacuum device 50 is positioned in fluid communication with the first access port 42 and at a location such that the first access port 42 is located between the vacuum device 50 and the first end of the sampling line. The positioning of the vacuum device and first access port may be described also in terms of blood sample flow. The vacuum device 50 is positioned so that the vacuum device can be used to draw a blood sample from the subject and direct the blood sample to the first access port 42. The vacuum device 50 is thus considered upstream of the first end of the sampling line and upstream of the first access port 42.

[0063] Referring again to FIGs. 7 and 9, the embodiment may further include a shut off valve 52 located between either the second access port 48 or the vacuum device 50, depending on the embodiment. The shut off valve 52 may be used to maintain a blood sample at the first access port 42 after a blood draw to facilitate blood sampling. The shut off valve may not be required where a syringe or controlled pump or valve system is used to draw and hold the sample. However, where a manual vacuum, such as a manual pump is used, the shut off valve may be closed after the blood draw to maintain a vacuum and thereby the blood at the first access port 42 for sampling.

[0064] In FIGs. 7 and 9, the alternative access device 40 is located in-line with the flow controller 20 and the first end of sampling line 22. In some embodiments, such as depicted in FIG. 10, the alternative access device 40 can be located in a separate line connected to the sampling line by a y-junction 54, such that the flow controller is located upstream in the other line of the y-junction. In this embodiment, a separate vacuum device from the flow controller would be used to draw a blood sample to the first access port 42. A separate shut off valve 56 would be located in the line between the y-junction and the flow controller so as to shut off the line when drawing blood to the first access port. [0065] FIG. 11 depicts a perspective view of the embodiment of FIG. 9. As illustrated, the embodiment includes a first access port 42, a vacuum device 50, and a shut off valve 52. As illustrated, an analyte test strip 58 is being inserted into the first access port 42 to perform sampling of the subject's blood. The opposite end of the test strip 58 is inserted into an analyte measurement device 60 for determining a concentration of an analyte under study, such as blood glucose.

[0066] A method for measuring an analyte in a subject's blood is also disclosed.

The method of one embodiment comprises providing an intravascular blood analyte monitor system comprising: 1) a sampling line comprising a first end configured for location in the vasculature of a subject; 2) an analyte sensor in fluid communication with the first end of the sampling line; 3) a flow controller in fluid communication with a second end of the sampling line for controlling the flow of blood to and from the subject for contacting the analyte sensor with blood from the subject; and 4) a first access port located between the first end of the sampling line and the flow controller, the first access port configured for receiving a sample receiving end of an analyte test strip. The method further comprises inserting a sample receiving end of an analyte test strip into the first access port to expose the sample receiving end of the analyte test strip to the subject's blood and determining a blood analyte concentration of the subject's blood using the analyte test strip.

[0067] The results of the analyte measurement from the test strip can be used in various ways. In some embodiments, the results can be used as an independent verification of current analyte concentration. In other embodiments, the results may be used in conjunction with data from the analyte monitoring system for purposes of calibration, trend analysis, etc. For example, in one embodiment, a method of the present invention may further comprise determining a blood analyte concentration of the subject's blood using the analyte sensor. An offset value representing a difference between an analyte concentration determined from the analyte test strip and an analyte concentration determined from the analyte sensor could then be generated.

[0068] Where the analyte measurement device 60 and test strip 58 are considered of sufficient accuracy, the results from the test strip may be used as a data point for calibrating the analyte sensor based on the offset value. Alternatively, the test results and offset value to compensate subsequent analyte concentration values determined from samples of the subject's blood using analyte test strips.

[0069] As an example of the latter scenario, one or more readings from an analyte measurement device 60 could be taken over time and compared with corresponding readings from the analyte monitoring system 10. This can be used to determine an accurate offset between the readings of the two devices, such that once the analyte monitoring system is removed from the subject, subsequent readings from the analyte measurement device 60 can be applied to this offset to provide a more accurate analyte reading.

[0070] As another example, one or more readings from an analyte measurement device 60 could be taken over time and compared with corresponding readings from the analyte monitoring system 10. Trending information may be established indicating a drift by either the measurement device 60 of the analyte monitoring system 10.

[0071] Although many embodiments of the present system have just been described above, the present system may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Also, it will be understood that, where possible, any of the advantages, features, functions, devices, and/or operational aspects of any of the embodiments of the present system described and/or contemplated herein may be included in any of the other embodiments of the present system described and/or contemplated herein, and/or vice versa.

[0072] While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad system, and that this system not be limited to the specific constructions and arrangements shown and described, since various other changes, combinations, omissions, modifications and substitutions, in addition to those set forth in the above paragraphs, are possible. Those skilled in the art will appreciate that various adaptations, modifications, and combinations of the just described embodiments can be configured without departing from the scope and spirit of the system. Therefore, it is to be understood that, within the scope of the appended claims, the system may be practiced other than as specifically described herein.

Claims

WHAT IS CLAIMED IS:

1. An intravascular blood analyte monitoring system for measuring analytes in a blood sample from a subject, wherein said system comprises:

a sampling line comprising a first end configured for location in the vasculature of a subject;

an analyte sensor in fluid communication with the first end of said sampling line; a flow controller in fluid communication with a second end of said sampling line for controlling the flow of blood to and from the subject for contacting said analyte sensor with blood from the subject; and

a first access port located between the first end of said sampling line and said flow controller, said first access port configured for:

fluid communication with said sampling line;

receiving at least a portion of a sample receiving end of an analyte test strip; and

introducing a blood sample from the subject to the at least a portion of the sample receiving end of the analyte test strip for analyte measurement.

2. The system of claim 1 further comprising a vacuum device positioned in fluid communication with said first access port and at a location such that said first access port is located between said vacuum device and the first end of said sampling line.

3. The system of claim 2 further comprising a shut off valve positioned between said vacuum device and said first access port.

4. The system of claim 1, wherein said first access port comprises a septum comprising an aperture having at least one dimension in the range of 5 to 10 millimeters for receiving the sample receiving end of the analyte test strip.

5. The system of claim 1, wherein said first access port comprises a septum comprising an aperture having at least one dimension greater than or equal to 6 millimeters for receiving the sample receiving end of the analyte test strip.

6. The system of claim 1, wherein said first access port comprises a septum comprising an aperture for receiving the at least a portion of the sample receiving end of the analyte test strip, wherein said aperture is resealable.

7. The system of claim 6, wherein said first access port has a volume of between one nanoliter and one milliliter.

8. The system of claim 1 further comprising a second access port positioned in fluid communication with said first access port and at a location such that said first access port is located between said second access port and the first end of said sampling line.

9. The system of claim 8, wherein said second access port comprises a septum comprising an aperture having at least one dimension in the range of 0.1 to 5 millimeters for receiving a syringe.

10. The system of claim 8, wherein said second access port comprises a luer for connecting said second access port to a syringe.

11. A method for measuring an analyte in a subject' s blood comprising:

providing an intravascular blood analyte monitoring system comprising:

an analyte sensor in fluid communication with the first end of said sampling line;

a flow controller in fluid communication with a second end of said sampling line for controlling the flow of blood to and from the subject for contacting said analyte sensor with blood from the subject; and

a first access port located between the first end of said sampling line and said flow controller, said first access port configured for receiving at least a portion of a sample receiving end of an analyte test strip;

inserting the first end of said sampling line into the vasculature of the subject; inserting at least a portion of a sample receiving end of an analyte test strip into said first access port to expose at least a portion of the sample receiving end of the analyte test strip to the subject's blood; and

determining a blood analyte concentration of the subject's blood using the analyte test strip.

12. The method of claim 11 further comprising determining a blood analyte concentration of the subject's blood using the analyte sensor.

13. The method of claim 12 further comprising determining an offset value representing a difference between an analyte concentration determined from the analyte test strip and an analyte concentration determined from the analyte sensor.

14. The method of claim 13 further comprising calibrating the analyte sensor based on the offset value.

15. The method claim 13 further comprising using the offset value to compensate subsequent analyte concentration values determined from samples of the subject's blood using analyte test strips.

16. The method of claim 11 comprising applying a vacuum pressure at a location upstream from the first access port and the first end of said sampling line so as to draw blood from the subject to the location of the first access port.