Patent Publication Number: US-8523797-B2

Title: Automated point-of-care fluid testing device and method of using the same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. 119 of U.S. Ser. No. 61/051,572 filed May 8, 2008. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to an automated repetitive point-of-care fluid testing device for gathering information about the quantity of certain analytes in a patient&#39;s blood, and/or properties of the patient&#39;s blood. The present invention utilizes a system that includes both an in-line testing region, and an off-line testing region. 
     BACKGROUND 
     Modern medical devices, including medical pumps, are increasingly being controlled by microprocessor based systems to deliver fluids, solutions, medications, and drugs to patients. A typical control for a medical pump includes a user interface enabling a medical practitioner to enter the dosage of fluid to be delivered, the rate of fluid delivery, the duration, and the volume of a fluid to be infused into a patient. Typically, drug delivery is programmed to occur as a continuous infusion or as a single bolus dose. 
     Many patients who are connected to a medical pump may be receiving an acute level of care, such as that provided in a hospital intensive care unit (“ICU”). A patient in an ICU is likely suffering from a very serious medical problem, that often is life threatening. As such, frequent monitoring of the patient&#39;s condition is required, including regular blood tests to determine quantities of analytes present in the blood, and to determine properties of the patient&#39;s blood. Examples of analytes in a patient&#39;s blood that may require monitoring include: glucose, lipid profiles (e.g., cholesterol, triglycerides, LDL and HDL), microalbumin, hemoglobin A 1C , fructose, lactate, bilirubin, and other known analytes. One property of a patient&#39;s blood that may require monitoring is the coagulation rate of the blood. Since coagulated blood cannot be returned to the patient, coagulation tests are typically done off-line in a remote laboratory and take considerable time to complete. 
     Unfortunately, caregivers in an ICU are very busy and may be unavailable to collect a sample from a patient at an appointed time, due to the needs of other patients. Further, equipment needed to perform tests on a sample in a location remote from the patient, such as in a lab, may also be unavailable or unable provide results in a timely manner. Additionally, many patients in an ICU are in such grave condition that only a limited amount of blood may safely be drawn from the patient. Furthermore, a caregiver may have difficulty in finding an appropriate location to collect blood samples from the patient. 
     Failing to properly monitor analyte levels or other properties of the patient&#39;s blood can lead to adverse effects for the patient. Thus, an automated system to collect and analyze a sample from the patient from a give collection site at preset intervals may improve the level of care the patient receives. Based on results of the testing, the patient&#39;s medication may be adjusted, or other treatments for the patient may be deemed proper or necessary. Further, it is desirable to be able to perform different types of tests on the sample, including in-line testing, and off-line testing. Still further, it is desirable to test a small fluid sample. For in-line testing it is desirable to draw, test, and re-infuse the blood sample in a time period short enough to prevent any significant clotting in the sample. Therefore, a need exists for an automated point-of-care in-line testing unit that performs both in-line and off-line testing, as desired in a flexible, programmable, timely, safe, and efficient manner. 
     SUMMARY 
     According to one embodiment, a point of care fluid testing system for determining properties of a fluid comprises a patient connection, a primary fluid routing portion, a pump, a secondary fluid routing portion, and a flushing fluid connection. The patient connection is adapted to connect the system to a patient to collect a fluid sample. The primary fluid routing portion has a pump region, a fluid transfer region, and an in-line testing region. The pump region is adapted to pump the fluid sample from the patient to the testing portion, and further to pump a substantial portion of the fluid sample from the primary fluid routing portion back to the patient following testing. The in-line testing region is adapted to evaluate at least a first characteristic of the fluid sample. The fluid transfer region being adapted to allow a portion of the fluid sample to be transmitted out of the primary fluid routing portion. The pump interacts with the pump region of the primary fluid routing portion. The secondary fluid routing portion includes an off-line testing portion that is adapted to receive the portion of the fluid sample transmitted out of the primary fluid routing portion via the fluid transfer region. The off-line testing portion is further adapted to evaluate a second characteristic of the fluid sample. The flushing fluid connection is adapted to connect the system to a flushing fluid to flush the system following the pumping of the fluid sample back to the patient. 
     According to one method, at least two characteristics of a fluid sample of a patient are evaluated. The method attaches a fluid connector to a patient. A fluid testing system is provided for determining properties of a fluid. The fluid testing system has a patient connection, a primary fluid routing portion that has a pump region, a fluid transfer region, and an in-line testing region. The testing system further has a secondary fluid routing portion that includes an off-line testing portion. The testing system also has a communications device. The fluid connector attaches to the patient connection of the testing system. A fluid sample is collected from the patient via the fluid connector and the patient connection using the pump region of the testing system to draw the fluid sample from the patient to the primary fluid routing portion of the testing device. The fluid sample is analyzed in the in-line testing region of the primary fluid routing portion to determine a first characteristic of the fluid sample. A portion of the fluid sample transfers through the fluid transfer portion of the primary fluid routing portion to the off-line testing portion of the secondary fluid routing portion. A second characteristic of the fluid sample is determined in the off-line testing portion. The remaining portion of the fluid sample returns to the patient, following the transfer, via the fluid connector and the patient connection using the pump region of the testing system to pump the fluid sample back into the patient. 
     According to another embodiment, a disposable primary fluid routing portion comprises a pump region, a fluid transfer region, and an in-line testing region. The pump region is adapted to interact with a reversible pump to draw a fluid sample into a disposable testing portion for testing and to pump most of the fluid sample out of the disposable testing portion back in the direction from which the fluid sample entered the pump region. The fluid transfer region is adapted to allow a portion of the fluid sample to be transmitted through the fluid transfer region and out of the primary fluid routing portion. The in-line testing region has an analyzer adapted to analyze the fluid sample to determine a first characteristic of the fluid sample 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a testing system according to one embodiment; 
         FIG. 2  shows a more detailed schematic view of disposable portions of a testing system according to the embodiment of  FIG. 1 ; 
         FIG. 3  shows a more detailed schematic view of reusable portions of the testing system according to the embodiment of  FIG. 1 ; 
         FIG. 4  is a pictorial view illustrating a testing system according to a further embodiment; 
         FIG. 5  is a pictorial view illustrating disposable components of the testing system according to the embodiment of  FIG. 4 ; 
         FIG. 6  is a sectional view of a connector taken along line  6 - 6  of  FIG. 5 ; 
         FIG. 6   a  is a sectional view showing the connector of  FIG. 6  assembled with distal tubing and a catheter; 
         FIG. 6   b  is a sectional view showing a prior art standard Luer connector assembled with distal tubing and a catheter; 
         FIG. 7  is an exploded view illustrating a disposable testing cassette for use with the testing system according to the embodiment of  FIG. 4 ; 
         FIG. 7   a  is a cross-section view taken along line  7   a - 7   a  of  FIG. 7 ; 
         FIG. 7   b  is pictorial view illustrating a testing system according to yet a further embodiment; 
         FIG. 8   a  is a cross-section view taken along line  8 - 8  of  FIG. 7  depicting a valve portion of the cassette in a closed position; 
         FIG. 8   b  is a cross-section view taken along line  8 - 8  of  FIG. 7  depicting a valve portion of the cassette in an open position; 
         FIG. 9  is a pictorial view illustrating a disposable off-line testing disk for use with the testing system shown in  FIG. 4 ; 
         FIG. 10  is a pictorial view illustrating movable mechanisms of the testing system according to the embodiment of  FIG. 4 ; 
         FIG. 11  is a pictorial view depicting a peristaltic pump mechanism for use with the testing system shown in  FIG. 4 ; 
         FIG. 12  is a cross-sectional view taken along line  12 - 12  of  FIG. 10  depicting the peristaltic pump interacting with the cassette for pumping fluid into or out of the cassette; 
         FIG. 13  is a pictorial view illustrating an actuator adapted to operate the valve of the cassette as shown in the embodiment of  FIG. 7 ; 
         FIG. 14   a  is a cross-sectional view depicting the actuator depicted in  FIG. 13  interacting with the cassette with the valve in a closed position; 
         FIG. 14   b  is a cross-sectional view depicting the actuator depicted in  FIG. 13  interacting with the cassette with the valve in an open position; 
         FIG. 15  is a bottom pictorial view of a rotating mechanism for the disposable off-line testing disk for use with the testing system shown in  FIG. 4 ; and 
         FIG. 16  is a top pictorial view of a rotating mechanism for the disposable off-line testing disk for use with the testing system shown in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will be described herein an example of the invention. The present disclosure is to be considered as an example of the principles of the invention. It is not intended to limit the broad aspect of the invention to the examples illustrated. 
       FIG. 1  is a schematic representation of a point-of-care testing system  10  comprising a main body  100  adapted to be attached to a patient via two attachment straps  101 . The attachment straps  101  may attach the main body  100  of testing device  10  to the patient via a VELCRO® fastener or other similar temporary attachment methods, such as an adhesive, that allows the attachment straps  101  to be removably attached to each other to secure the main body  100  to a desired location. For example, it may be convenient to attach the main body  100  of the system  10  to the patient&#39;s arm. In such a situation the attachment straps  101  would be wrapped around the patient&#39;s arm in such a manner to secure the main body  100  to the patient. According to one embodiment the main body  10  is relative small, having a volume of less than about twenty (20) cubic inches, and weighing less than about two (2) pounds. It is further contemplated that the main body  100  may additionally be contoured to be applied to a specific body part of a patient, such as a forearm, leg, or abdomen. While such a contour is not required, it may improve patient comfort. It is contemplated that in many cases the forearm will serve as a beneficial mounting location based on the ease of access and the number of blood vessels in the forearm. The main body  100  may be reusable, in that it may be used on more than one patient, by following proper cleaning and sterilization techniques before being used with another patient. It is further contemplated that the main body  100  can be releasably secured to a bed rail, pole, or other support structure near the patient&#39;s bedside rather than being worn by the patient. 
     The testing system  10  additionally comprises a disposable portion  200 . The disposable portion, described in more detail below, is adapted to be used with only one single patient and may require periodic replacement on that patient. 
     A catheter  205  is adapted to be placed into a blood vessel of the patient. The catheter  205  may be a standard 20 Gauge×2 inch catheter, or other commonly available catheter appropriate for the blood vessel utilized. Depending on the application, the blood vessel selected may be an artery or a vein. If blood gas levels, or properties that may vary based on blood gas levels, are to be monitored the blood vessel selected will be an artery. A vein may be used if blood gases are not of interest or do not affect the property or properties to be determined using the testing system. The main body  100  of the testing system is preferably located near the location where the catheter  205  is placed into the blood vessel, in order to minimize the volume of blood needed for a sample. It is contemplated that the main body  100  will be positioned within one hundred centimeters (100 cm), more preferably within about twenty centimeters (20 cm), of the location the catheter  205  enters the blood vessel. 
     As shown in  FIGS. 1-3 , the main body  100  houses, removably receives, or operatively couples with two disposable portions, a primary fluid routing portion  201  and a secondary fluid routing portion  300 . The primary fluid routing portion  201  has an in-line testing region that includes an in-line sensor  209 . The secondary fluid routing portion  300  includes a secondary fluid routing portion  301 . The primary fluid routing portion  201  and the secondary fluid routing portion  300  are selectively connectable in fluid communication through a fluid transfer region  210 . As used herein, in-line testing refers to blood testing where substantially all of the blood that enters the testing portion may be returned to the patient, while off-line testing is used to refer to blood testing where the blood will not be returned to the patient. As shown in  FIG. 1 , the secondary fluid routing portion  300  is connected to the primary fluid routing portion  201 . Thus, the blood that enters the secondary fluid routing portion  300  of the system  10  was initially within the primary fluid routing portion  201 . Only a relatively small fraction of the blood within the primary fluid routing portion  201  is transferred into the secondary fluid routing portion  300 . For example, but by now way of limitation, when the sample is five hundred microliters (500 μL) the portion transferred to the secondary fluid routing portion could be fifty microliters (50 μL). 
     The testing system  10  additionally comprises a flush solution reservoir  207 . The flush solution reservoir  207  contains a flush solution adapted to flush the blood out of the system  10  prior to the initiation of a test, or to reinfuse the blood back to the patient following the completion of a test. The flush solution may be a medically-approved water-based solution including but not limited to saline, dextrose and water, potassium chloride, electrolytes, etc. The flush solution additionally may be used to prime the testing system  10  prior to connecting the system to the patient. The system  10  may need to be primed to ensure that air is not present in fluid passages of the system  10 . It is additionally contemplated that the flush solution may contain one or more substances used to calibrate an in-line test sensor  209  ( FIG. 2 ) of the primary fluid routing portion  201 . The initial volume of flush solution within the flush solution reservoir  207  should be sufficient to prime the testing system  10  and operate the system  10  for a period of from about 12 hours to about 96 hours. According to some embodiments the initial volume of flush solution may range from about 100 mL to about 1000 mL. It is additionally contemplated according to some embodiments that some portion of the flush solution within the reservoir  207  may be used to keep the patient&#39;s blood vessel open at the site of the catheter  205 . 
     The primary fluid routing portion  201  and the secondary fluid routing portion  300  are adapted to be placed within the main body  100  of the testing system  10  by a caregiver at the start of care of the patient, or when the portions  201 ,  300  need replacement. It is contemplated that the portions  201 ,  300  may be used for a period of up to 96 hours prior to replacement. 
     Additionally shown in  FIG. 1  is control device  400 . The main body  100  of the testing system  10  communicates with a control device  400 . The control device  400  has a user interface  401  to allow the caregiver to view results of tests performed automatically by the system  10  and to set the frequency of testing. The user interface  401  may be a touch screen, or other known user interface types, to allow the caregiver to easily communicate with the system  10 . The control device  400  may be an infusion pump, such as a SYMBIQ® infusion system or pump by Hospira, Inc., that is being used to provide medication or other fluids to a patient. Wireless communication between the main body  100  of the testing system  10  and the control device  400  is preferred, as a wireless system does not require the caregiver to route communication cables from the body  100  to the control device  400 . However, it is contemplated that in some situations the communications between the main body  100  and the control device  400  will be carried via a wire or cable. Alternatively, it is contemplated that the main body  100  of the testing system  10  can have its own integral control device and/or user interface to display test results and accept operational commands. The test results over a particular selectable time period of interest can be displayed in graphical or other suitable format. 
     Turning now to  FIG. 2 , additional details of the disposable portion  200  of the system  10  are shown. The disposable portion  200  provides a continuous fluid passage from the patient&#39;s blood vessel via the catheter  205  through the main body  100  of the testing system  10  and to the fluid reservoir  207 . The disposable portion  200  has a distal end at the catheter  205  that is inserted into the patient&#39;s blood vessel. The catheter  205  connects to a distal connecter  204  that is also connected to a first fluid line portion  202 . The first fluid line portion  202  runs from the distal connector  204  to the primary fluid routing portion  201  within the main body  100  (shown in broken lines in  FIG. 2 ) of the testing device  10 . The first fluid line portion  202  is a flexible tubing that may be conveniently routed by the caregiver. The first fluid line portion  202  may be from about 10 cm to about 50 cm in length, and preferably has an internal volume of less than about two-hundred microliters (200 μL). 
     The distal connector  204  may be of any suitable leak-proof design, such as a Luer type connector, that preferably has a fluid volume of less than about twenty microliters (20 μL) when the connector  204  is connected to the catheter  205  and the first fluid line portion  202 . 
     The disposable portion  200  additionally comprises a second fluid line portion  203 . The second fluid line portion  203  runs from the primary fluid routing portion  201  within the main body  100  to a proximal connecter  206  connected to the flush solution reservoir  207 . It is contemplated that the second fluid line portion  203  may be significantly longer than the first fluid line portion  202  in order to conveniently locate the flush solution reservoir  207  away from the patient, such as on a fixed or portable bedside pole. It is contemplated that the internal volume of the second fluid line portion  203  may be more than ten times the internal volume of the first fluid line portion  202 . Providing the second fluid line portion  203  with much greater internal volume than the first fluid line portion  202  reduces the likelihood of contaminating the flush solution reservoir with blood that has entered the system  10 . The proximal connector  206  may be a Leur type connector, a tapered spike, needle cannula, or any other known type of connector for accessing the fluid in the reservoir  207 . 
     As shown in  FIG. 2 , the primary fluid routing portion  201  may be divided into three main regions, a fluid pumping region  208 , a fluid testing region  209 , and a fluid transfer region  210 . The primary fluid routing portion  201  may be in the form of a disposable cassette containing the pumping region  208 , the fluid testing region  209 , and the fluid transfer region  210 . The total volume of fluid within the primary fluid routing portion  201  is preferably less than three hundred microliters (300 μL). The fluid testing region  209  can be an in-line fluid testing region. 
     The pumping region  208  of the primary fluid routing portion  201  is a fluid passage that interacts with a pump contained in the main body  100 . The pumping region  208  may have an elastic region, such as a silicone membrane or polymeric tubing, which engages a peristaltic-type pump, or other type pump, within the body  100 . The pumping region  208  allows for bi-directional flow within the primary fluid routing portion  201 , i.e., fluid may flow either away from the patient or back towards the patient, depending upon the operation of the pump. The pumping region  208  further is adapted to stop all flow within the primary fluid routing portion  201  when the pump is stopped. Flow may be stopped in order to perform certain fluid testing within the in-line fluid testing region  209  of the primary fluid routing portion  201 . 
     The fluid testing region  209  is a fluid passage having at least one integrated sensor adapted to determine information about the patient&#39;s blood. The information may include determining the level of certain analytes within the blood, such as the patient&#39;s blood glucose level. The sensor disposed within the testing region  209  can be a single use sensor, but is more preferably a reusable sensor capable of performing a plurality of blood sample analyte measurements over the life of the disposable portion  200  or the primary fluid routing portion  201 . The testing region  209  may contain a sensor, or sensors, capable of measuring blood glucose, blood gases, electrolytes, lactate, and other analytes. The sensor, or sensors, of the testing region  209  may utilize electrochemical, optical, calorimetric, or other known technologies for measuring blood analytes. The testing region  209  additionally is adapted to electrically communicate results of testing to the rest of the system  10 , such as by electrodes or other wired or wireless circuitry. 
     Still referring to  FIG. 2 , the fluid transfer region  210  of the primary fluid routing portion  201  allows a small volume of blood within the primary fluid routing portion  201  to be deposited, expressed, or otherwise transferred to the secondary fluid routing portion  300 . The blood, or other fluid, that is transferred to the secondary fluid routing portion  300  never reenters the primary fluid routing portion  201 , but remains in secondary fluid routing portion  300 . The fluid transfer region  210  allows the secondary fluid routing potion  300  to be utilized to perform testing that takes a longer period of time to perform, or requires a reaction that makes the blood unsuitable to return to the patient. A non-limiting example of a test to be performed in the secondary fluid routing portion  300  is a blood coagulation test, as coagulated blood should not be returned to the patient. 
     It is contemplated that the small volume of blood transferred through the fluid transfer region  210  to the secondary fluid routing portion  300  should be less than about twenty microliters (20 μL) per transfer. It is contemplated that a transfer through the transfer region  210  of the primary fluid routing portion  201  to the secondary fluid routing portion  300  may be made every time a blood sample is taken from the patient via the system  10 . It is further contemplated that some tests utilizing the secondary fluid routing portion  300  may not need to be taken as frequently as tests utilizing the testing region  209  of the primary fluid routing portion  201 , and in such a situation a portion of only selected blood samples would need to be transferred through the transfer region  210  to the secondary fluid routing portion  300 . 
     In some embodiments, a plurality of transfers through the transfer region  210  to the secondary fluid routing portion  300  and secondary fluid routing portion  301  may be made per blood sample. For instance, a small amount of flushing solution may first be transferred to the secondary fluid routing portion  300  prior to any blood being pumped into the primary fluid routing portion  201 . Then blood from the patient may be transferred from the primary fluid routing portion  201 . Finally, a third transfer may provide flushing solution into the secondary fluid routing portion  300  as the flushing solution is used to pump the blood from the primary fluid routing portion back into the patient. 
     The transfer region  210  of the primary fluid routing portion  201  may have a valve, a fluid circuit, or other known fluid transfer device that can be activated by a mechanism located remotely or within the main body  100  in order to facilitate the transfer of fluid from the primary fluid routing portion to the secondary fluid routing portion. The transfer region  210  must be designed to prevent leakage of fluid, prevent the introduction of air, and prevent the introduction of microbes during the transfer from the primary fluid routing portion  201  to the secondary fluid routing portion  300 . Additionally, the transfer region  210  must permit a plurality of transfers to occur successively, without becoming either clogged or adversely affected by fluids previously transferred during the lifespan of the primary fluid routing portion  201 . 
     The disposable secondary fluid routing portion  300  is in fluid communication with the primary fluid routing portion  201  via the transfer region  210 . The secondary fluid routing portion  300  has an off-line testing portion  301  comprising one or more, more preferably an array or plurality of spaced apart single use diagnostic sensors  301 . However, it is contemplated that the invention can be used with multiple use sensors as well. The sensors  301  may be, but are not limited to, blood coagulation sensors, such as for use with a PT, aPTT, or ACT blood coagulation test. The fill volume for each sensor  301  is preferably less than about twenty microliters (20 μL). The secondary fluid routing portion  300  is adapted to sequence the sensors  301  such that each sensor  301  can receive a volume of blood transferred from the transfer region  210  of the primary fluid routing portion  201 , while also preventing the sample volume from contacting other sensors in the array. The sensors  301  may be sequenced by a rotating platform, a linear translating platform, a fluid circuit with valves that operate sequentially, or other known sequencing methods. The sample transferred into the secondary fluid routing portion  300  may reach an individual sensor  301  via capillary action, or by pumping from the pumping region  208  of the primary fluid routing portion  201  for a brief time period, such as less than ten seconds. 
     The secondary fluid routing portion  300  additionally is adapted to electrically communicate results of testing on a test sensor  301  to the rest of the system  10 , such as by electrodes, or other wired or wireless circuitry. The secondary fluid routing portion  300  may also be positioned within the main body  100  in order to receive heat from a heater  106  within the main body  100 , such that any tests performed in the secondary fluid routing portion are performed under proper temperature conditions. 
     The secondary fluid routing portion  300  is adapted to contain from about 1 to about 36 test sensors  301 , depending on the required frequency of off-line testing. Due to the fluid transfer region  210 , if the secondary fluid routing portion  300  contains single use sensors  301  or supports a different frequency of testing that the primary fluid routing portion  201 , the secondary fluid routing portion can be removed from the main body  100  independently of the primary fluid routing portion  201 , without having to remove the system  10  from the patient. Thus, a caregiver may replace the secondary fluid routing portion  300  while the testing system  10  is still connected to the patient and without the need to change the primary fluid routing portion  201 . This is particularly useful if the number of off-line test sensors  301  that may be placed in the secondary fluid routing portion  300  is small, or if a caregiver determines that a different analyte level or blood property needs to be monitored on the patient. 
     Turning next to  FIG. 3 , the reusable main body  100  of the testing system  10  is shown in more detail. The main body  100  is adapted to be used on a plurality of patients over a number of years. It is contemplated that the main body  100  may be used for up to three years or longer with proper care. Proper sterilization and cleaning procedures must be followed between uses of the main body  100  on different patients. The main body  100  comprises an opening  102  for receiving one or more of the disposable portions  201 ,  300 , a pump  103 , a fluid transfer mechanism  104 , an off-line sensor indexer  105 , a heating element  106 , a controller  107 , and a power source  108 . 
     The main body  100  has an access door  111  (not shown) that allows a caregiver to access the opening  102 , such as to replace the primary fluid routing portion  201 , or the secondary fluid routing portion  300  (shown in broken lines). Typically a caregiver will use the access door  111  to place a primary fluid routing portion  201  and the secondary fluid routing portion  300  into the body  100  at the beginning of use of the system  10  on a particular patient, and to remove the testing portions  201 ,  300  from the body  100  at the conclusion of use of the system  10  on the patient. Additionally, the access door  111  may be positioned so as to be utilized to replace the secondary fluid routing portion  300  while the system is connected to the patient. 
     The pump  103  is a mechanism, such as a peristaltic pump, piezo element, magnetic field, or other known pump type, that causes fluid to flow inside of the pumping region  208  of the primary fluid routing portion  201 . Preferably, the pump  103  is bi-directional or capable of causing fluid to flow in either direction, away from the patient or towards the patient, within the testing system  10 . However, a uni-directional pump can be used with appropriate valving to achieve bi-directional flow. The flow rate provided by the pump  103  must be sufficient to allow testing operations to be completed within a two minute period by drawing blood into the system, performing in-line testing, transferring blood for off-line testing, and re-infusing the blood remaining in the primary fluid routing portion back into the patient. The pump  103  is also adapted to completely stop flow within the primary fluid routing portion  201 , such as when an in-line test is performed in the in-line testing region  209 . 
     Still referring to  FIG. 3 , the fluid transfer mechanism  104  may include a motorized cam, a piston, a magnet, or other known methods to cause the transfer region  210  of the primary fluid routing portion  201  to transfer fluid from within the primary fluid routing portion to the secondary fluid routing portion  300 . 
     The sensor indexer  105  may be a rotational motor or linear motor, or other type device that positions an individual sensor  301  relative to the transfer region  210  to receive fluid from the primary fluid routing portion  201  via the transfer region  210 . 
     The heating element  106  provides thermal energy to regulate the temperature of at least one of the sensors  301  of the secondary fluid routing portion  300  to help ensure accurate test results. For example, the heating element may regulate the temperature of the sensor  301  to about 37° C. during the period of testing for a blood coagulation sensor. It is contemplated that the heating element  106  may be stationary and the sensor indexer  105  will position the individual sensor  301  near the heating element  106 . Alternatively, the heating element  106  may be movable so as to be positioned near the individual sensor  301  or both the heating element  106  and the sensor  301  may be movable for that purpose. It is additionally contemplated that a plurality of heating elements  106  may be provided such that every individual sensor  301  of the secondary fluid routing portion  300  is provided with a heating element  106 . 
     A reusable fluid sensor  211  may additionally be incorporated into the main body  100  and is functionally engaged with the in-line testing region  209  of the disposable portion  200 . The fluid sensor  211  produces a signal, such as an electric signal, that varies in strength based on the composition of the fluid in the in-line testing region  209 . The fluid sensor  211  may be used for determining, for example, if a blood sample has been drawn into the in-line testing region  209 , and subsequently, if the blood sample has been fully flushed from the in-line testing region  209  by a flush solution after an in-line diagnostic test has been performed. The fluid sensor  211  may also be used for detecting the presence of an unwanted air pocket inside the test region. The fluid sensor  211  can thereby add a measure of efficacy to the testing system  10  by providing an ability to confirm proper flow of blood and flush solution inside the disposable portion  200  while ensuring that no air is present. 
     The reusable fluid sensor  211  may comprise an optical sensor, such as a paired LED emitter and photo-detector unit, or some other reusable sensor capable to distinguish between blood, flush solution, and air within a sensing zone of the disposable portion  200 . Alternatively, the fluid sensor  211  may be a suitable disposable design that is integral to the disposable portion  200  and comes into contact with the fluid, such as an electrochemical or electrically conductive sensor, which is disposed along with the cassette upon completion of use on a patient. Furthermore, the fluid sensor  211  may alternatively be located elsewhere in the disposable portion  200  or elsewhere along the disposable set; however, it is preferred to locate the sensor  211  in close proximity to where the blood sample is tested for diagnostic analysis. 
     The controller  107  is adapted to operate and functionally coordinate all of the electromechanical components, such as the pump  103 , the fluid transfer mechanism  104 , the off-line sensor indexer  105 , and the heating element  106  of the testing system  10 . The controller  107  also allows the main body  100  to communicate with the control device  400  ( FIG. 1 ) to report test results from the testing system  10  or to obtain instructions from the caregiver entered via the control device  400 . 
     The power source  108  of the main body  100  is a battery, such as a lithium ion battery, that provides sufficient power to operate the system for an extended period of time, such as between eight and seventy-two hours. Alternatively, the power source  108  may be an A/C power source. If the power source  108  is a battery, it may be rechargeable or disposable. It is contemplated that if a rechargeable battery is used for the power source  108 , the power source may be recharged while the system  10  is in use on a patient. 
     Referring now to  FIG. 4 , a more detailed embodiment of a point-of-care testing system  1000  is shown. The testing system  1000  comprises a reusable main body  1100 , a disposable assembly  1200 , including the primary fluid routing portion  1201  and the secondary fluid routing portion  1300 , described in greater detail in connection with  FIG. 5 , a catheter  1205  to connect to a blood vessel of a patient, a flush solution reservoir  1207 , and a control device  1400 . The testing system  1000  shown in  FIG. 4  is adapted to perform an in-line blood glucose test and an off-line blood coagulation test; however, it is contemplated that other analytes or blood properties could be tested as described in connection with  FIGS. 1-3 . 
     The main body  1100  has a primary fluid routing portion access door  1102  and a secondary fluid routing portion access door  1111 . The primary fluid routing portion access door  1102  allows a care giver to access the primary fluid routing portion  1201 , while the secondary fluid routing portion access door  1111  allows a caregiver to replace the secondary fluid routing portion  1300  without having to worry about disrupting the primary fluid routing portion  1201 . The main body  1110  shown in  FIG. 4  measures approximately 4.75″×3.75″×1.7″ giving a total volume of approximately 30 cubic inches. The main body  1100  has a total weight of about 0.75 lbs. A strap  1101  with a VELCRO® type connector allows the main body  1100  to be releasably secured to a patient, such as by attaching the strap  1101  around a patient&#39;s arm or leg. 
     The control device  1400  shown in  FIG. 4  is a SYMBIQ® infusion system or pump from Hospira. The control device  1400  has a touch screen user interface  1401  to allow the caregiver to enter instructions for the testing system  1000  and to view results of tests performed by the testing system  1000 . For flexibility in locating the components and reduction of wires at the bedside, the control device  1400  and the main body  1100  communicate wirelessly in the embodiment shown in  FIG. 4 , although a wired connection would also suffice. 
       FIG. 5  illustrates the disposable portions  1200 ,  1300  of the testing system  1000 . The disposable portion  1200  provides the main fluid path of the testing system  1000 . The disposable portion  1200  has the catheter  1205  at a distal end and the flush fluid reservoir  1207  at a proximal end. The catheter  1205  connects to a distal connector  1204 . The distal connector  1204  also connects to a first fluid line portion or distal tubing  1202 . The first fluid line portion  1202  runs from the distal connector  1204  to the primary fluid routing portion  1201 . The first fluid line portion  1202  has a length of about 25 cm, and an inner diameter of about 0.030″, giving the first fluid line portion  1202  a relatively small internal volume of 114 μL. 
     As shown in  FIGS. 6   a  and  6   b , the distal connector  1204  is a low-volume distal connector. The low volume of the distal connector  1204  is obtained by providing a bore  1211  having a 1 cm length and a 0.030″ diameter, providing a volume of about 5 μL. As best seen in  FIG. 6   a , the outer surface  1212  of the distal connector is designed to be completely inserted into the catheter  1205 , thereby eliminating any excess fluid volume in the catheter  1205  caused by incomplete insertion. The diameter of the bore  1211  matches the diameter of the bore  1222  of the distal tubing  1202 . Further, a receptacle  1213  is sized and shaped to allow a complete insertion of the distal tubing  1202  into the distal connector  1204 , eliminating any excess volume or dead space caused by incomplete insertion of the distal tubing  1202 . Thus, the low volume distal connector  1204  of  FIGS. 6 and 6   a  offers improvements over a prior art Luer type connector shown in  FIG. 6   b  by reducing the internal volume of the fluid flow path between the blood vessel and the primary fluid routing portion  1201  and eliminating dead spaces where fluid may tend to stagnate. In the connector  1204   b  of  FIG. 6   b , the bore  1211   b  does not match the bore  1222  of the distal tubing  1202 , the outer surface  1212   b  is not designed to be completely inserted into the catheter  1205 , and the receptacle  1213   b  is not sized and shaped to allow complete insertion of the distal tubing  1202 . This causes dead spaces or locations, generally designated at  1222 ,  1223 , and  1224  where blood may collect and resist flushing back into the patient following in-line testing. The connector  1204  of the present invention provides a substantially smooth, continuous, uninterrupted fluid flow path that is free from dead spaces or locations where blood may collect and resist flushing back into the patient. Blood is not allowed to stagnate in the lines, posing health risks to the patient or caregiver and possibly skewing results of subsequent tests. 
     Referring back to  FIG. 5 , the primary fluid routing portion  1201  has a pumping region  1208 , a testing region  1209 , and a fluid transfer region  1210 . The fluid transfer region is aligned with the secondary fluid routing portion  1300  to provide a sample to a test sensor  1301  ( FIG. 9 ) of the secondary fluid routing portion  1300 . The primary fluid routing portion  1201  has an internal flow path with a volume of about 175 μL. Thus, the primary fluid routing portion  1201  and the first fluid line portion  1202  combine to have a volume of about 295 μL. In order to ensure that a proper blood sample is obtained, approximately two to four times this volume of blood must be removed from the patient; hence, between 600 and 1200 μL of blood is required from the patient to perform a test. However, a majority of this blood will be infused back to the patient. 
     The primary fluid routing portion  1201  connects to a second fluid line portion  1203  that also connects to a proximal connector  1206  at the flush fluid reservoir  1207 . The second fluid line portion has a length of about 90 cm and an internal diameter of about 0.054″, providing an internal volume of about 1330 μL. 
     Turning now to  FIG. 7 , an exploded view of the primary fluid routing portion  1201  is provided. In this embodiment, the primary fluid routing portion  1201  has a lid  1201   a  and a base  1201   b . A flexible silicone diaphragm  1214  seals the primary fluid routing portion from fluid leakage, as well as preventing air or other outside contaminants from entering the primary fluid routing portion  1201 . An in-line test sensor  1215  is provided in the primary fluid routing portion  1201  to measure the concentration of glucose within the blood that enters the primary fluid routing portion  1201 . The test sensor  1215  includes electrodes  1216  that are exposed outside of the primary fluid routing portion  1201  to provide the results from the test sensor  1215  to the system  1000 . The sensor  1215  is a thick-film design having a glucose-oxidase reagent that is reusable for up to 1000 test cycles over a 30 day period. The primary fluid routing portion  1201  additionally forms a fluid channel  1217  running the length of the primary fluid routing portion  1201 . 
     In addition to the in-line test sensor  1215 , the primary fluid routing portion  1201  has a fluid sensing zone  1225 . Fluid that enters and exits the primary fluid routing portion  1201  passes through the fluid sensing zone  1225 . It is contemplated that the fluid sensing zone  1225  is an optically transparent material, such as, for example, a clear polycarbonate polymeric material. The fluid sensing zone  1225  is located near, and generally proximal to, the in-line test sensor  1215 , to allow an identification to be made of fluid within the primary fluid routing portion  1201  and nearing the test sensor  1215 . The close proximity of the fluid sensing zone  1225  to the in-line test sensor  1215  allows the testing system  1000  to determine that a desired fluid to be sampled is in contact with the test sensor  1215 . 
     Turning now to  FIG. 7   a , a sectional view taken through line  7   a - 7   a  of  FIG. 7  is shown.  FIG. 7   a  shows a raised fluid channel portion  1226  of the fluid channel  1217  within the fluid sensing zone  1225 . Fluid within the fluid channel  1217  that enters the fluid sensing zone  1225  passes through the raised fluid channel  1226 . The raised fluid channel  1226  allows an optical sensor ( 1227   FIG. 7   b ) to transmit light through the fluid sensing zone  1225  and generate an output used to determine what type of fluid is present within the fluid sensing zone  1225 . The raised fluid channel portion  1226  extends beyond, generally higher, than the remainder of the fluid channel  1217 , and the in-line test sensor  1215 . 
       FIG. 7   b  shows an arrangement of the fluid sensing zone  1225  and an optical sensor  1227 . The optical sensor  1227  is contained within the main body  1100 . It is contemplated that the optical sensor  1227  may be located within the primary fluid routing portion access door  1102 . The optical sensor  1227  positions around the fluid sensing zone  1225  when the primary fluid routing portion  1201  is within the main body  1100  and the access door  1102  is closed. The access door  1102  has been removed from  FIG. 7   b  for greater clarity. The optical sensor  1227  may be an LED type sensor. That is, light is emitted from an LED of the optical sensor  1227 , the light passes through the fluid sensing zone  1225 , and the light is detected by an optical detector of the optical sensor  1227 . The optical detector of the optical sensor  1227  generates an output related to the intensity of the light received by the optical sensor  1227 . 
     Various fluids that are typically found within the fluid sensing zone  1225  have distinct optical properties such that the output signals of the optical sensor  1227  for the various fluids within the sensing zone  1225  are distinguishable. Light is altered by refraction, scattering, reflection, and absorption as it passes through a fluid present in the sensing zone  1225  as it passes from the LED to the optical detector of the optical sensor  1227 . Put another way, the intensity of the light that reaches the optical detector of the optical sensor  1227  allows a determination to be made of the fluid, blood, flush solution, air, or some other fluid, present within the sensing zone  1225 . 
     The output of the optical sensor  1227  may then be compared to stored light intensity profiles to allow a determination of the identity of the fluid within the sensing zone  1225 . For example, a light intensity profile for blood and a light intensity profile for flush solution may be stored on a memory. An algorithm executed by a processor compares the output generated by the optical sensor  1227  with stored light intensity profiles to determine the identity of the fluid present in the sensing zone  1225 . Additionally, a processor may determine that the output generated by the optical sensor  1227  is not consistent with any stored pattern, and alert a caregiver that a malfunction has occurred, such as an abnormal fluid flow condition, or the presence of an air slug within the line. 
       FIGS. 8   a  and  8   b  depict a cross section taken along line  8 - 8  of  FIG. 7  showing the fluid transfer region  1210  of the primary fluid routing portion  1201 . The fluid transfer region  1210  has a valve  1218  that comprises a silicone valve plug  1219 , that may be integrally formed with the diaphragm  1214 ; a valve nozzle  1220 , that may be formed into the base  1201   b  of the primary fluid routing portion  1201 ; and a leaf spring  1221  that connects to and exerts a force on the valve plug  1219  to keep the valve closed until activation is desired. As shown in  FIG. 8   a , the valve plug  1219  is in the closed position, and fluid is not allowed to pass through the valve, but fluid may flow in the fluid channel  1217  of the primary fluid routing portion  1201 . As shown in  FIG. 8   b , the valve plug  1219  is in the open position, and fluid is allowed to pass through the valve nozzle  1220 . 
     In  FIG. 9 , the secondary fluid routing portion  1300 , where secondary testing such as off-line testing can be done, is depicted. The secondary fluid routing portion  1300  has at least one test sensor  1301 , which may be a single use or multiple use sensor. Optionally, an absorbent pad  1302  can be provided. The exemplary embodiment depicted in  FIG. 9  shows that the secondary fluid routing portion  1300  can include a plurality of test sensors  1301  and a plurality of absorbent pads  1302 . The test sensors  1301  shown are single use blood coagulation sensors. The coagulation test sensors  1301  may use a PT reagent, an aPTT reagent, or an ACT reagent. A sample of blood from the primary fluid routing portion  1201  is transferred through the fluid transfer region  1210  and onto the test sensor  1301  for off-line testing. It is contemplated that a sample as small as 5 μL may be used for blood coagulation testing with a PT reagent. The test sensor  1301  can absorb a 5 μL sample in about 5 seconds using capillary action. Electrodes (not shown) relay the results of the coagulation test to the system  1000 . 
     Turning now to  FIG. 10 , mechanisms for operating moving components of the system  1000  are shown. The system  1000  has a pump  1103 , a valve actuator  1104 , and an off-line testing portion sensor indexer  1105 . The pump  1103  and the valve actuator work in conjunction with the primary fluid routing portion  1201  of the system  1000 , while the off-line testing portion sensor indexer  1105  works in conjunction with the secondary fluid routing portion  1300 . 
     The pump  1103  is shown in more detail in  FIG. 11 . The pump  1103  has a motor  1112 , a peristaltic portion  1113  having peristaltic fingers mounted on a camshaft, and a set of gears  1114  to allow the motor  1112  to drive the peristaltic portion  1113 . The motor  1112  is operable in either direction, thus allowing the pump to be operated to draw fluid into the primary fluid routing portion  1201 , or to pump fluid out of the primary fluid routing portion  1201  or back in the direction from which it entered. Therefore, the pump  1103  provides for bidirectional flow within the system  1000 . 
       FIG. 12  depicts a cross-section showing the pump  1103  interacting with the pump region  1208  of the primary fluid routing portion  1201 . The peristaltic fingers of the peristaltic portion  1113  of the pump  1103  compress the silicone diaphragm  1214  in the pump region  1208  of the primary fluid routing portion  1201 . The fingers sequentially press against the diaphragm  1214  to cause fluid to flow in flow channel  1217  of the primary fluid routing portion  1201  and the system  1000 . As is well known in the peristaltic pump field, at least some of the fingers are positioned to compress the diaphragm  1214  sufficiently so that no fluid may flow through the flow channel  1217  when the pump  1103  is not in operation and the cassette  1201  is properly installed. 
     Next,  FIGS. 13 ,  14   a , and  14   b  show the valve actuator  1104  in more detail. The valve actuator  1104  has a motor  1115  that drives a camshaft  1116  via gears  1117 . The cam shaft  1116  operates a valve pin  1118  and a diaphragm pin  1120 . The valve pin  1118  has a spring  1121  and the diaphragm pin  1120  has a spring  1122  that hold the pins  1118 ,  1120  in contact with the camshaft  1116 . The valve pin  1118  has a magnet  1119  on the end of the pin closest to the primary fluid routing portion or cassette. To open the valve  1218 , as shown in  FIG. 14   b , the camshaft  1116  turns, allowing the spring  1121  to push the valve pin  1118  away from the primary fluid routing portion  1201 . The magnet  1119  lifts up a leaf spring  1221  that is connected to the valve plug  1219 , pulling the valve plug  1219  away from the valve nozzle  1220  to allow fluid to flow through the valve nozzle  1220 . Simultaneously, the motion of the camshaft  1116  causes the diaphragm pin  1120  to move towards the primary fluid routing portion  1201 . The diaphragm pin  1120  compresses the silicone diaphragm  1214  so that fluid may not be pumped distally beyond the location of the pin  1120  in the flow channel  1217  of the primary fluid routing portion  1201 . When the valve plug  1219  is positioned to allow flow through the valve nozzle  1220 , the pump  1103  may be run for a short period of time to more quickly drain fluid from the primary fluid routing portion  1201  to the secondary fluid routing portion  1300 . Once the fluid has been transferred to the secondary fluid routing portion  1300 , the camshaft  1116  rotates to push the valve pin  1118  back towards the primary fluid routing portion  1201 , thus replacing the valve plug  1219 . Simultaneously, the diaphragm pin  1120  is moved away from the primary fluid routing portion to allow flow to resume through the flow channel  1217 , as shown in  FIG. 14   a . The period to open or close the valve  1218  is less than five seconds. 
     Referring now to  FIGS. 15 and 16 , the off-line sensor portion indexer  1105  is depicted. The sensor indexer  1105  has a carousel  1123  that supports the off-line testing portion  1300  to properly position the off-line test sensors  1301  and the absorbent pads  1302 . The sensor indexer  1105  drives the carousel  1123  via geared surface  1124 . The rotational position of the carousel  1123  is sensed by monitoring movement of flags  1125  through an optical detector  1126 . A set of pins  1127  contact electrodes on the off-line test sensors  1301  to obtain results from the off-line test sensors. Also shown is a heater  1106  used to maintain an appropriate temperature of the off-line test sensor  1301  being used. The heater has an aluminum element  1128  that contact the sensor  1301  to transfer heat to the sensor  1301 . The element  1128  is heated by a Kapton pad  1129  that is electrically energized. A thermistor  1130  embedded in the element  1128  monitors the temperature. The heater  1106  is mounted in a fixed location, and an individual sensor  1301  is rotated to the heater  1106  by the carousel  1123 . Alternatively, each sensor  1301  may include a heater  1106  that rotates with it or the heater  1106  can be on a second carousel geared to rotate relative to the sensor carousel  1123 . 
     Referring again to  FIG. 1 , a method of using the point-of-care testing system  10  on a patient may comprise attaching the main body  100  to the patient&#39;s forearm to monitor blood glucose level and coagulation (aPTT) rate at prescribed intervals of time over a twenty-four hour period. An infusion system or pump  400  near the patient has been configured to function as the graphical user interface  401  for the system  10  via wired or wireless communication. The infusion pump  10  may also serve to deliver one or more drugs to the patient, such as insulin and heparin. 
     A caregiver or clinician gathers the basic components of the system in preparation for use on the patient, including the main body  100 , the disposable portion  200  (including the primary fluid routing portion  201  and/or the secondary fluid routing portion  300 ), and the reservoir of flush solution  207 . The clinician also obtains a standard catheter  205  suitable for drawing blood from a peripheral vein on the patient&#39;s forearm. The disposable  200  portion incorporates a glucose sensor in the diagnostic sensor region  209 , and the disposable secondary fluid routing portion  300  incorporates an array of six aPTT coagulation sensors. 
     The clinician attaches the body  100  to the patient via the attachment features  101 , such that the body  100  is located about three inches from a site chosen to catheterize a peripheral vein or artery. In the embodiment shown, the forearm provides a convenient location for mounting the body  100  to the patient and accessing a peripheral blood vessel, although other mounting locations and blood vessel access points are possible. 
     The clinician then assembles the disposable portions  200 ,  300  of the system, by connecting the distal connector  204  to the catheter  205 , connecting the secondary fluid routing portion  300  to the primary fluid routing portion  201 , and connecting the proximal connector to the flush solution  207  reservoir. 
     The clinician primes all the fluid passages in the system  10  with flush solution by holding the flush solution reservoir  207  at an elevation that causes gravity to force the flush solution through all passages from the reservoir  207  to the tip of the catheter  205 . The clinician observes that all air has been removed from these passages. 
     The clinician inserts the catheter  205  into the peripheral vein or artery on the patient, using appropriate hospital procedures, to provide access to the patient&#39;s blood vessel. 
     The clinician immediately installs the primary fluid routing portion  201  and the secondary fluid routing portion  300  into the main body  100  via the opening  102  ( FIG. 3 ). When the opening  102  is closed by the door  111 , the installation automatically prevents the flow of flush solution inside the primary fluid routing portion  201 , by virtue of the pump  103  engaging the primary fluid routing portion  201 . The clinician then hangs the flush solution reservoir  207  on a bedside pole. 
     The clinician activates (“turns on”) the invention via the graphical interface  401  on the infusion pump  400 . The system  10  is subsequently energized by the internal power source  108 . Wireless communication between the main body and the infuser  400  begins, via a set of wireless transmission components on the electronic controller  107  and in the infuser  400 . 
     The clinician programs the system  10  via the graphical interface  401  to perform a series of 24 blood draws on the patient, spaced 1 hour apart. Furthermore, the clinician programs the invention to perform a glucose test on each blood sample drawn, and also to perform an aPTT test on every second blood sample drawn (i.e., at 2-hour intervals). The net result will be 24 glucose tests and 12 aPTT tests uniformly spaced over a 24-hour period. 
     The system  10  begins to respond to the instructions programmed by the clinician. All acts done by the system  10  to perform successive cycles of drawing, testing, and re-infusing the blood sample are coordinated by the electronic controller  107  using power from the power source  108 . 
     The sensor indexer  105  is briefly activated to prepare one of six aPTT sensors  301  to receive a blood sample from the fluid transfer region  210  and to receive heat from the heating element  106 . 
     The heating element  106  is activated, causing the aPTT sensor in to reach a temperature of 37° C. within about 30 seconds. 
     The pump  103  is activated for about 20 seconds, causing the cassette pumping region  208  to draw about 1 mL of blood from the patient through the catheter  205  into the disposable portion  200 , reaching a maximum point somewhere in the proximal tubing  203 . The incoming blood displaces and partially mixes with the flush solution in the disposable portion  200 ; however, sufficient flush solution is displaced from the sensor region  209  and the transfer region  210  to permit accurate diagnostic measurements on the blood sample. 
     The pump  103  is deactivated upon completion of the draw, preventing any further flow of blood or flush solution in the system  10 . 
     The glucose sensor in the sensor region  209  is activated to begin a measurement of glucose concentration in the blood sample. 
     The fluid transfer mechanism  104  is briefly activated, causing the fluid transfer region  210  to transfer a 10 μL volume of blood sample to the aPTT sensor  301 . The transfer is assisted by a brief activation of the pump  103  to exert fluid pressure on the 10 μL blood sample until it completely fills the off-line test sensor  301 . This transfer process takes about 5 seconds to complete. 
     The aPTT sensor  301  is activated to begin an aPTT measurement on the blood sample. The heating element  106  continues to operate to maintain the sensor  301  and blood sample at a temperature of 37° C. 
     The glucose sensor in the sensor region  209  completes the measurement of glucose concentration in the blood sample after about 20 seconds of test time. The result is read electronically by the electronic controller  107  which wirelessly transmits the result to the graphical interface  401  for the clinician to observe. 
     The pump  103  is activated for about 60 seconds, causing the pumping region  208  to re-infuse the blood sample in the disposable in-line portion  200  back to the patient via the catheter  205 . Virtually all of the 1 mL of drawn blood is re-infused, excluding the 10 μL sample transferred to the aPTT sensor  301 . This pumping process also causes about 1 mL of flush solution  207  to be infused into the patient, which helps to cleanse the fluid passages in the system  10  and the catheter  205  from any residual blood that may impair the operation of the system  10 . 
     The pump  103  is deactivated upon completion of the re-infusion step, preventing any further flow of flush solution in the system  10 . 
     The aPTT sensor  301  completes the measurement of aPTT in the blood sample after about 120 seconds of test time. The result is read electronically by the electronic controller  107  which wirelessly transmits the result to the graphical interface  401  for the clinician to observe. 
     The heating element  106  is deactivated, causing its temperature level to equilibrate with the surrounding ambient temperature within a few minutes. 
     The system  10  remains idle for nearly 1 hour in preparation for the next programmed blood draw and test cycle. The total cycle time to perform the blood draw, glucose test (with blood transfer step), and re-infusion step is about 100 seconds. 
     At programmable predetermined intervals, by way of example and not limitation approximately hourly, the system automatically repeats the above tests as programmed. However, all steps involving the aPTT test can be performed according to the same or a different programmable schedule, for example an aPTT test may be performed only for every second cycle per the clinician&#39;s instructions. 
     Once all six aPTT sensors  301  have been consumed during operation of the system  10  (i.e., after 11 cycles of operation), the electronic controller  107  wirelessly instructs the infuser  400  and graphical display  401  to notify the clinician. The clinical responds by detaching the secondary fluid routing portion  300  from the main body  100  via the access door  111 , and replaces it with a fresh secondary fluid routing portion  300 . The clinician or caregiver then discards the consumed secondary fluid routing portion  300  per hospital procedures. 
     Upon completion of use of the system  10  on the patient for the desired number of cycles of operation, the clinician disconnects the system from the patient. The clinician removes the catheter  205  from the patient according to hospital procedure, and removes the main body  100  from the forearm via the attachment features  101 . The clinician then removes the testing portions  201 ,  300  from the main body  100  via the access door  111 . The clinician discards the catheter  205 , testing portions  201 ,  300  and the flush solution container  207  per hospital procedures. 
     As described with respect to the glucose/coagulation sampling and test examples above, the in-line sensors and the off-line sensors can measure a different characteristic of the fluid sample. Alternatively, the in-line sensors and the off-line sensors can measure the same fluid sample characteristic. In one example, both the in-line and off-line sensors can measure glucose. A single use off-line strip, such as is known in the art, can be used periodically (daily, hourly, or before, during or after selected cycles of in-line testing) to calibrate or mathematically correct for any drift in an in-line glucose sensor. If the in-line sensor was more stable and accurate than the off-line sensor, the in-line sensor could be used to calibrate or adjust readings from the off-line sensor. Such ability to cross calibrate the sensors is advantageous. In the case of calibrating the in-line sensor with the off-line sensor, it could even eliminate the need for the flush solution to have calibration traits, reducing costs and potential risks of adverse reactions with the flush solution. In any event, the need for other blood draws to check the accuracy of the sampling system  10  would be reduced. 
     It is further contemplated that the either of the in-line sensors or off-line sensors can include multiple sensors for sensing the same or different characteristics of the fluid sample. For example, the in-line sensor may include multiple sensors—all for glucose or one for glucose, one for lactate, etc. The in-line sensors may be similar or of different types. Likewise for example, the off-line sensor may include multiple sensors—all for coagulation or one for coagulation, one for glucose, etc. The off-line sensors may be similar or of different types. Multiple off-line sensory arrays can be operatively brought into position to receive a fluid sample through the valve. A single expression of a fluid sample can be routed to multiple off-line sensors through capillary action or other known methods. 
     One of the advantages of the invention is the capability to program and selectively run an in-line test, an off-line test or both according to the condition of the patient and the desire of the clinician. The sampling interval can be preset, but also can be dynamically adjusted or tailored based upon the results obtained or clinician preferences. For example, the system  10  can be programmed to measure both coagulation and glucose every thirty minutes during the initial few hours a patient is in an intensive care unit following surgery. Then, the expression of samples for coagulation testing can be reduced in frequency if the clinician desires or the sample readings are as expected or desired. If an unexpected reading is encountered, the frequency can be increased or the appropriate in-line and/or off-line test or re-test automatically initiated. To minimize the number and volume of blood draws from patients, the system  10  can selectively run only one of the sensors at a time if desired. For example, if the in-line sensor gives an unexpected reading, it is possible to selectively repeat testing only with that sensor. This has the beneficial result of minimizing the number of expressions (opening of the valve or fluid transfer region) for off-line testing since each expression results in a brief, controlled breach of the sterile field. 
     It is contemplated that the system  10  can include a fill port at the fluid transfer region  210 , between the pump  103  and the fluid source  207 , or between the pump  103  and the catheter  205 . The fill port is used for drawing blood, manually or more preferably automatically, into a test tube or other suitable known container for subsequent analysis at a remote laboratory or analyzer. The fill port can be provided on a Y site connected to the primary fluid routing portion  200 . The pump  103  can be programmed to draw blood into the test sample container on demand or at static predetermined or dynamic intervals for more complete blood panels. The patient is freed from more frequent sticks with needles, which also reduces the risk of needle sticks for clinicians and reduces hazardous waste. 
     While the foregoing has described what is considered to be the best mode and/or other examples, it is understood that various modifications may be made and that the subject matter disclosed herein may be implemented in various forms and examples, and that they may be applied in numerous other applications, combinations and environments, only some of which have been described herein. Those of ordinary skill in that art will recognize that the disclosed aspects may be altered or amended without departing from the true scope of the subject matter. Therefore, the subject matter is not limited to the specific details, exhibits and illustrated examples in this description. It is intended to protect any and all modifications and variations that fall within the true scope of the advantageous concepts disclosed herein.