Abstract:
A system and method is provided including a fluid communications network that sends priming and waste fluid to a waste bag, obviating the presence of open fluid containers in an operating room or catheter lab. The fluid communications network is constructed and arranged to allow nearly automated priming and bubble removal, thereby reducing the possibility of operator caused errors in set-up and reducing the time required for set-up. The fluid communications network is useable for attachment to a balloon catheter for inflation thereof. In order to provide greater control and automation of the inflation of the balloon catheter, a conversion kit is provided that can be used to convert an existing automatic injector into an injector useable for automatically controlling the small amount of injection fluid typically associated with balloon catheters.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to provisional application Ser. No. 60/268,568, entitled MEDICAL DEVICE WITH AUTO START-UP, filed Feb. 14, 2001, and to provisional application Ser. No. 60/269,112, entitled AUTOMATED BALLOON INFLATION DEVICE USED IN CONJUNCTION WITH AN AUTOMATED VARIABLE DISPENSING RATE INJECTION SYSTEM, filed Feb. 15, 2001, and claims priority from both of these provisional applications. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The device pertains to a disposable tubing kit that is attachable to a syringe of an automatic injection device. Automatic injection devices, such as applicants&#39; device described in U.S. Pat. No. 6,099,502 and incorporated by reference herein, are used to deliver fluids such as saline and contrast agents through a catheter to a patient. The devices typically include a motor-driven linear actuator that forces a plunger through a syringe, thereby creating a desired fluid flow into the patient. For sanitation purposes, the syringe and all associated tubing between the patient and the syringe are disposable. 
         [0003]    Preparing the automatic injection device for operation is a time-consuming process. Various tubes must be connected together and to the device. The operator preparing the injection device for operation must be careful to ensure that the connections are tight and that none of the tubes are pinched or otherwise blocked. Furthermore, during the assembly process, the operator will prime various subassemblies with saline and contrast before connecting them to other subassemblies. Priming is done to prevent air from being introduced into the patient. Intermittent priming steps are performed so that fluid-to-fluid connections may be made at predetermined assembly steps. For purposes of this discussion, a fluid-to-fluid connection between two components is made by priming each component so that menisci form at their open ends. The ends are then connected together, thereby merging the menisci and ensuring no air is introduced into the connection. 
         [0004]    Priming the subassemblies is performed by injecting a desired fluid into the subassembly until the fluid exits the opposite end. The exiting fluid is usually directed into a waste pan, but occasionally spills onto the floor, creating a potential slip hazard, or onto the patient, who is awake during most of the procedures involving the automatic injection device. In addition to creating slip hazards or causing discomfort to the patient, there is growing interest in minimizing the presence of open fluid containers in medical environments. This is especially true for bodily fluids, such as blood, which present a potential biohazard. 
         [0005]    Once assembled, the components are again primed with fluid to prevent air from being injected into the patient. While priming, the operator taps on the various components in an attempt to dislodge air bubbles from their inner walls. The entire set-up process typically takes 10 to 15 minutes and requires a trained operator. Opportunity for error exists even when the set-up is carefully performed by a trained operator. 
         [0006]    Some completely assembled, disposable kits are available that include a syringe that is pre-loaded with contrast agent. These kits overcome some of the aforementioned difficulties but present their own challenges to the manufacturer. All medical devices must be delivered sterile and are thus sterilized prior to shipping. Present methods of sterilization include heating using wet or dry autoclaving, gamma irradiation, or EtO sterilization. Each method has drawbacks. Dry autoclaving requires very high temperatures to overcome the lack of heat transfer inherent in dry systems. Wet or steam autoclaving causes dimensional increases in plastic components as the moisture penetrates the plastic and a subsequent decrease as the moisture later escapes. Steam autoclaving further uses a temperature which may cause the polymeric parts to deform. Gamma irradiation requires the use of gamma-stable components and, further, degrades contrast agents, and EtO requires a subsequent out-gassing step to remove byproducts of the sterilization process, and is also expensive, inflexible and difficult to verify or control. 
         [0007]    Regardless of whether the syringe is pre-filled, once the set-up is complete, the physician positions a catheter into the patient. The use and type of the catheter varies depending on the procedure being performed. For example, the catheter may be used to deliver contrast agents, using the aforementioned injection device, or to provide a guide for routing bioptomes, ultrasonic imaging probes, or balloon devices. 
         [0008]    Some of the devices require fluid flow, such as the balloon devices, and are connected to special manual syringes. These special syringes are called “inflators” and use a plunger that is manually advanced using a rod that is threaded into a handle to allow the operator to advance the plunger using very small, controlled increments. However, these threads also give the physician such a mechanical advantage as to take away the “feel” of the balloon inflation. Thus, the physician cannot feel the effect the balloon is having on the wall of the vessel it is stretching. For example, the physician cannot feel a calcium deposit cracking. The special syringes typically include a pressure gauge but it is located on the syringe itself and is impractical for the physician to monitor the gauge as he or she is often watching an image of the balloon being inflated on a monitor. It would be advantageous to use the automatic injection device to accomplish controlled injections of fluid for purposes such as inflating balloons so that a greater degree of inflation accuracy and control is achieved and so a more precise and accurate feedback loop is attained. However, automatic injection devices are generally constructed and arranged to accommodate a large-capacity syringe such as the syringe used to inject contrast agent. This type of syringe is too large to be used for balloon inflation because the injection device cannot move the linear actuator over a short enough distance and with the necessary precision and accuracy for a balloon inflation procedure. Additionally, the larger syringe exhibits greater compliance. To provide the necessary accuracy, a smaller syringe would have to be used so that a given linear distance traveled by the actuator results in a much smaller volume of liquid being injected. However, a small syringe, such as the manual syringe used to inflate a balloon, is not compatible with the present automatic injection devices. 
         [0009]    There is a need for a device and method for reducing the set-up time associated with using an automatic injection device. 
         [0010]    There is also a need for a device that minimizes the chances of error by an operator in setting up an automatic injection machine for use. 
         [0011]    There is a further need for a device and method that improves management of waste while performing catheter-based surgical procedures. 
         [0012]    There is thus a need for an adapter that would allow the automatic injection device to be used to inject small, precisely measured and controlled amounts of fluid. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    The present invention includes a method and device for inflating a balloon using an automatic inflation device. The device for inflating a balloon includes a significantly smaller syringe than that typically used in the automatic inflation device. The smaller syringe provides increased control over the administration of a small quantity of fluid. An adapter sleeve is provided that is attachable to an automatic injector device to provide support for the smaller syringe. Present automatic injection devices, such as the CL100 designed by Acist Medical Systems, Inc. of Eden Prairie, Minn., are designed for large volume injections of contrast media. These devices are designed to accept large syringes. The adapter sleeve, thus, has an outside diameter or dimension substantially equal to that of a syringe used in the device for contrast agents, and an interior diameter or dimension substantially equal to that of the balloon syringe. 
         [0014]    The automatic injector is programmed to provide a balloon inflation mode of operation. Once the sleeve and balloon inflation syringe are installed, the device may be used to automatically fill the syringe with contrast agent or saline. The device may be placed in inflation mode manually, or it may be constructed and arranged to automatically detect the presence of the adapter sleeve and place itself into inflation mode accordingly. Preferably the linear actuator and motor of the automatic injector are used to act on the plunger or “wiper” of the balloon inflation syringe. Alternatively, an adapter may be provided including an auxiliary linear actuator device driven by a linear stepper motor, hydraulic cylinder, piezoelectric inch-worm handheld actuator, or the like. 
         [0015]    In addition to a physiologic pressure transducer, which provides a pressure input to the monitor for display or other purposes that is representative of biological pressures, one aspect of the invention is a pressure sensor for measuring a pressure representative of the pressure in the balloon. Balloon pressures are significantly higher than biologic pressures. To avoid damaging the sensitive physiologic pressure transducer, the present invention provides a pressure sensor that is separate from the physiologic pressure transducer. This sensor may be a separate pressure transducer, capable of higher pressures. Or it may be an indirect sensor, such as a motor torque detector, which provides a value, representative of motor torque, that can be converted to balloon pressure. Alternatively, strain gauges may be operatively attached to the housing structure surrounding the syringe to measure the axial load on the housing, which is representative of the pressure exerted by the fluid inside the syringe. 
         [0016]    Another aspect of the invention provides a fluid detection feature. This is a safety feature that insures against air being injected into the patient. This feature may be embodied in a passive coating on the interior surface of the syringe or tubing that reacts when contacted by a fluid. This feature may also be embodied by an active device using ultrasound, optics, or conductivity to determine the presence or absence of fluid in the syringe. 
         [0017]    The method of using the device to inflate a balloon begins by setting the device to the balloon inflation mode. Again, this preferably occurs automatically when the computer of the automatic inflation device receives a signal from a sensor that is constructed and arranged to detect the presence of the adapter sleeve. The adapter and syringe are then loaded onto the device. Next the balloon catheter is attached and all air is aspirated therefrom and expelled from the system. The balloon and associated tubing are then preloaded with either contrast agent or saline and primed. 
         [0018]    The balloon and automatic inflation device having thus been prepared, the balloon is inserted into the patient and positioned at the target site. The desired parameters are programmed into the device and inflation is initiated. One aspect of the present invention is that the desired parameters may be calculated automatically based upon inputted data such as patient weight, percent occlusion of the target vessel, type of balloon, etc. Further, the balloon inflation device may perform a small test inflation to determine the elasticity of the artery or vein from which the actual program function is determined. 
         [0019]    While the balloon is inflating, the inflation speed may either be preprogrammed and allowed to inflate in a fully automatic mode, or controlled from outside or within the sterile field with remote devices such as a handheld device or using a touch screen, in data flow communication with the computer, that is preferably covered with a transparent drape. The balloon pressure, balloon volume, and inflation time are outputted to a display screen. The pressure and volume are preferably also displayed as a graph as a function of time. The balloon pressure and volume are monitored for dilatation. A sudden increase in volume or a sudden decrease in pressure can indicate that a buildup of calcium in a blood vessel has cracked or “popped”, a desired result of balloon therapy for arteriosclerosis. This sudden spike in volume is followed by a subsequent pressure increase indicating a momentary or incremental pressure drop. If the pressure falls below a preset limit, corrected for volume, or is not regained by further inflation, the sudden pressure drop may be indicative that the balloon has ruptured. If it is determined that the balloon has ruptured, the procedure is stopped or reversed automatically or by depressing a stop button on the device. 
         [0020]    One aspect of the invention provides an automatic detection program that enables the computer controlling the automatic injection device to recognize the occurrence of a “pop” and to stop inflating thereafter, either by deflating the balloon (drawing back on the plunger—aspirating), by holding the balloon pressure constant for a predetermined time (moving the plunger forward under pressure control) or by providing keep-open flow (moving the plunger forward under flow control) or by simply halting motion of the plunger in either direction. This safety feature prevents the possibility of over-inflating the balloon, and thus stressing the blood vessel. The feature can also minimize the unnecessary introduction of fluid into the blood vessel in the event of a balloon rupture. 
         [0021]    Another aspect of the present invention provides an automatic detection program that measures the actual pressure in the balloon catheter, and the volume of fluid injected, and compares that data to baseline pressure data representative of inflation characteristics of the balloon catheter in controlled environment. The difference between actual data and baseline pressure data represents the effect of the patient on the balloon catheter. This information can be used to determine the effectiveness of the balloon catheter and may also be used to trigger certain actions by the computer. Such actions might include a shut down or aspiration if the data seems to indicate that there is a safety issue, such as a balloon rupture. Another action might be to hold the balloon pressure at a predetermined level for a period of time after a pop has been detected. Another action might be to follow a pressure versus time algorithm previously inputted into the computer. Yet another action executable by the computer is to control the balloon volume, regardless of, or in addition to, balloon pressure. 
         [0022]    The baseline pressure data will be different for various balloon catheters and is preferably provided in the form of a bar code or other form of computer readable data on or in the package of the balloon catheter. The automatic injection device includes a bar code reader or other correlative device usable to retrieve the baseline pressure data from the package. The computer can also be used to record the balloon pressure as a function of time or volume, baseline pressure as a function of time or volume, injection rate as a function of time, and any other data that the computer may be programmed to use or record so that each procedure, or case, can be recorded as a computer file and used later for analysis or as a record to be inserted into the patient&#39;s file. 
         [0023]    One embodiment provides the capability to create and display three-dimensional graphs that are easily readable by the physician. The third dimension may take the form of a conventional plane—style graph, i.e. a graph having x, y, and z axes. Alternatively a two dimensional plot may be provided using colors or audible tones to provide the third dimension. Example of three dimensional data sets include pressure, volume, and time; pressure, volume, and radiographic balloon opacity; pressure, volume and balloon diameter; and the like. 
         [0024]    Once the balloon treatment is complete, the balloon is deflated and the catheter is removed from the patient. The device may be stopped or it may be placed in a standby mode and used on another patient. The automatic detection program may include an automatic deflate mode whereby the movement of the syringe plunger is automatically reversed when the “pop” is detected, until it is determined the balloon is deflated. The pressure sensor may be used to determine whether the balloon is deflated. 
         [0025]    The automatic inflation device, combined with the automatic detection program, makes it possible to inflate multiple balloons simultaneously. By automating the procedure, the physician is free to concentrate on the device monitors and is thus able oversee multiple balloons. The automatic inflation device is further capable of being programmed in a phased manner such that the inflation of various balloons can happen either simultaneously or sequentially. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a diagrammatic representation of an embodiment of the fluid network of the present invention; 
           [0027]      FIG. 2  is a diagrammatic representation of an alternative embodiment of the fluid network of the present invention; 
           [0028]      FIG. 3  is a perspective view of a prior art automatic injector device that is convertible to a balloon inflation device of the present invention; 
           [0029]      FIG. 3A  is a perspective view of an adapter sleeve, useable to convert an automatic injector device into a balloon inflation device of the present invention; 
           [0030]      FIG. 3B  is a perspective view of a prior art injector subassembly of an automatic injection device; 
           [0031]      FIG. 4  is bottom view of a prior art syringe insertable into an injector device; 
           [0032]      FIG. 5  is a perspective view of the prior art syringe of  FIG. 4 ; 
           [0033]      FIG. 6  is a perspective view of a syringe of the present invention surrounded by an adapter sleeve of the present invention shown in phantom lines; 
           [0034]      FIG. 7  is an embodiment of a balloon inflation device of the present invention; 
           [0035]      FIGS. 8-10  are examples of pressure graphs shown on a display of the present invention during balloon inflation procedures. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    Referring now to the Figures, and first to  FIG. 1 , there is shown a fluid network  20  comprising a disposable patient manifold  22  connected to a saline line  24  and an output line  26 . The saline line  24  has a first end  28  and a second end  30 . The first end  26  is connected to a bag connector  32 , useable to establish fluid communication between the line  24  and a saline bag  34 . 
         [0037]    The patient manifold  22  is also connected to a syringe  36  of an automatic injection device (not shown) for receiving the fluid ejected therefrom. The patient manifold  22  is thus useable to selectably connect the output line  26  with either the saline line  24  or the syringe  36 . The patient manifold  22  may be any device capable of selectively directing flow between at least three ports, such as a three-way check valve, a manual or automatic three-way stopcock, a motor operated valve, or a collection of check valves operably disposed within the appropriate lines to effect the desired flow directions. Preferably, the patient manifold  22  comprises an automatic valve that is constructed and arranged such that fluid communication normally exists between the saline line  24  and the output line  26 . However, when a predetermined amount of positive fluid pressure is generated by the syringe  36 , the fluid pressure causes the fluid communication between the saline line  24  and the output line  26  to become blocked, and opens fluid communication between the syringe  36  and the output line  26 . An example of this type of patient manifold is the spring-loaded spool valve described in U.S. patent application Ser. No. 09/542,422, incorporated by reference herein in its entirety. To provide controlled saline pressure when the patient manifold  22  is aligned to deliver saline to the output line  26 , the saline line  24  is fed through a pump, preferably a peristaltic pump  62 , of the automatic injection device. 
         [0038]    The output line  26  is connected at a first end  38  to the patient manifold  22  and at a second end  40  to a three-way stopcock  42 . The three-way stopcock  42  may be manually or automatically operated and is also connected to a waste line  44  and a catheter connector  46  such that it may be used to align the output line  26  with either a catheter  48  or the waste line  44 . 
         [0039]    The waste line  44  has a first end  50  connected to the three-way stopcock  42  and a second end  52  connected to a three-way check valve  54 . The three-way check valve  54  is also connected to an auxiliary syringe  56  and a bag line  58 . The three-way check valve  54  is constructed and arranged so that the auxiliary syringe  56  may be used as a hand pump. When the wiper of the syringe  56  is withdrawn, the check valve  54  blocks the bag line  58  and directs fluid from the waste line  44  into the syringe  56 . When the wiper is then advanced, the check valve  54  blocks the waste line  44  and directs fluid from the syringe  56  into the bag line  58 . The bag line  58  is connected to a waste bag  60  where the waste fluid is deposited. When the syringe  56  is used to aspirate saline into the waste bag  60 , it is important that the saline line  24  is not compressed and occluded by the peristaltic pump  62 . 
         [0040]    Alternatively, as seen in  FIG. 2 , an automatic pump  70  may be used to pump liquid to the waste bag  60 . The automatic pump  70  is shown as a peristaltic pump that acts on the waste line  44 . As peristaltic pumps act on the outside of a tube, the waste line  44  and the bag line  58  are integral. 
         [0041]    The fluid network  20  is thus designed to be attached to an automatic injection device quickly and primed with little or no human interaction. The fluid network  20  is assembled, packaged and sterilized so that it may be shipped as a completely assembled kit. Preferably, the waste bag  60  doubles in function as the packaging bag in which all of the aforementioned components of the fluid communication network  20  are shipped. This eliminates the need for a separate packaging bag, an added expense. A divider  61  is integrated, preferably by heat sealing, into the bag to limit the amount of fluid that could spill from the bag  60  in the event of a leak developing around the connection  63  between the bag  60  and the bag line  58 . 
         [0042]    In use, the fluid network  20  is removed from its packaging and the patient manifold  22  is connected to the syringe of the automatic injection device. The saline line  24  is threaded through the peristaltic pump  62  and verification is made that the three-way stopcock  42  is aligned to the waste line  44 . Next, the bag line  58  is connected to the waste bag  60  and the saline line  24  is connected to the saline bag  34 . 
         [0043]    The fluid network  20  is now ready for priming. The automatic injection device, such as the device  102  shown in  FIG. 3  and discussed in more detail below, preferably includes a computer  106  having a program segment for instructing the device  102  to enter a priming mode. When selected, the priming mode program segment includes a command that causes the computer  106  to align the patient manifold  22  for contrast agent, or if the patient manifold  22  is a manually operated valve, displays a message instructing the operator to do so. The program segment prevents further action unless the computer  106  receives verification from the operator that the manifold  22  is aligned. Preferably, a patient manifold position detector  72  is operably connected to the manifold  22  and in communication with the computer  106 , obviating the need for verification from the operator. Once the position of the manifold  22  is verified, either by operator input or with the detector  72 , the program segment causes the computer  106  to send a signal to the linear actuator of the automatic injector that advances the plunger of the syringe  36  slightly to force potential air bubbles from the syringe connecting tube  66 , which connects the patient manifold  22  to the syringe  36 . Any air bubbles in the connecting tube  66  are forced into the output line  26 . 
         [0044]    The priming program segment  64  then aligns the patient manifold  22  for saline. After manifold position detector  72  verifies that the patient manifold  22  is aligned for saline, the peristaltic pump  62  is activated for a predetermined interval. The interval is long enough, for a given pump speed, to fill the saline line  24 , the patient manifold  22  and the output line  26  with saline. 
         [0045]    Preferably, the peristaltic pump  62  operates in a priming mode whereby it turns in a stutter fashion to send pressure pulses through the various lines. These pressure pulses act to dislodge air bubbles from the inner walls of the lines, thus obviating the need for the operator to tap on the lines during the priming procedure. To monitor for the presence of bubbles, a bubble detector  74  is placed in one or more locations and are electrically connected to the computer of the automatic injector. In priming mode, detection of bubbles is expected. However, when the injector is in injection mode, the receipt of a signal from the bubble detector(s)  74  will cause the injector to stop forward movement of the plunger of the syringe  36 . The waste bag  60  eventually receives all of the priming fluid. 
         [0046]    Alternatively, if a syringe pump (not shown) is used instead of a peristaltic pump  62 , the syringe may be operated by a linear actuator in a stutter fashion such that the linear actuator intermittently hammers on the plunger of the syringe thereby creating the necessary pressure pulses to dislodge air bubbles from the inner walls of the various lines. One skilled in the art will see that any pump substituted for the peristaltic pump  62  can be operated in an on and off fashion to create such pressure pulses. 
         [0047]    Priming having thus been completed, the attending physician may insert the catheter  48  into the target blood vessel and attach the catheter  48  to the fluid communication network  20  using the catheter connector  46 . The catheter  48  is then primed, and proper placement within the vessel is verified, by taking a suction on the catheter  48  until blood appears in the clear tubing of the output line  26 . Taking suction on the catheter  48  is performed by aligning the stopcock  42  to establish fluid communication between the output line  26  and the catheter  48 . Suction may then be drawn on the output line  26  by retracting the plunger of the syringe  36 , or reversing the rotation of the peristaltic pump  62 . However, it may be undesirable to establish reverse fluid flow into the syringe  36  or the saline bag  32 . Doing so prevents reuse of the saline remaining in the saline bag  34  and reuse of the contrast agent in the syringe  36 . More preferably, the output line  26  includes a disconnect  68  that allows the physician to connect a hand syringe to the output line  26  and take a suction thereon. Once blood appears in the clear output line  26 , the disconnect  68  is reconnected and the three-way stopcock  42  is aligned to the waste line  44 . The peristaltic pump  62  is then run in a forward direction to force the blood from the output line  26 , through the stopcock  42 , and into the waste line  44 . The waste bag  60  receives the blood and other waste fluids for safe containment and easy disposal. 
         [0048]    Referring now to  FIGS. 3 ,  3 A, and  3 B, another embodiment of the present invention provides an automatic balloon inflation device  100 . This embodiment of the balloon inflation device  100  is constructed and arranged to allow an existing automatic injection device  102 , such as the CL100 made by Acist Medical Systems, Inc. of Eden Prairie, Minn. and described in U.S. Pat. No. 6,099,502 incorporated by reference herein in its entirety. It is understood by one skilled in the art that a separate balloon inflation device could be constructed using the devices and techniques represented herein combined with the necessarily associated functionality of existing angiographic injectors. 
         [0049]    The automatic injection device  102  is converted into a balloon inflation device  100 , when it is accessorized to accept a small, balloon inflation syringe  104  ( FIGS. 6 and 7 ), and when the computer  106  of the injection device  102 , is updated with a program that allows the injection device  102  to operate in “Inflation Mode”. 
         [0050]    The example of an automatic injection device  102  shown in  FIG. 3  includes an injector subassembly  108  and a user-interface subassembly  110 . The injector subassembly  108  includes a syringe holder  112 , typically used to house a relatively large syringe body  114  having fluid capacities on the order of 10 cc to 250 cc, such as those used for angiography and shown in  FIGS. 4 and 5 . The syringe body  114  is equipped with a plunger  116 , slideably disposed therein. The plunger is acted upon by a linear actuator  118  ( FIG. 3 ) of the injector subassembly and is removably attached thereto. The particular angiography syringe body  114  shown in  FIGS. 4 and 5 , is fully described in U.S. Pat. No. 6,099,502 and includes features that an automatic injection device, the injector subassembly of which is shown in  FIG. 3B . These features are discussed briefly herein as they provide examples of injector-specific considerations that are made in the design of a conversion kit to allow the injector  102  to be used as a balloon injector  100 . These features may also be incorporated into the design of a balloon inflation syringe  104 . 
         [0051]    Thus, the angiography syringe  114  includes a wall  119  defining first and second opposite ends  122 , and  124 . The first end  122  corresponds to a distal end of the syringe  114 , and the second end  124  corresponds to a proximal end of the syringe  114 . The wall  119  of the syringe  114  is cylindrical in the illustrated embodiment and includes a central axis  126  extending longitudinally therethrough. 
         [0052]    The syringe body  114  defines a pumping chamber  128  in an interior thereof. A wiper or plunger  116  is located in the pumping chamber  128  and is constructed and arranged for reciprocal motion between a position adjacent to the first end  122  and the second end  124 . That is, when the syringe  114  is mounted in a system analogous to the angiographic system  102 , the linear actuator  118  from the system energizes the plunger  116  and causes it to move between the second end  124  and the first end  122 . A plunger support member  130  supports the plunger  116 . The support member  130  preferably comprises a rigid, hard material for example, a polycarbonate or ABS plastic, to interface between an actuator  118  and the plunger  116 . The member  130  attaches to the plunger  116  by a snap fit, a magnetic fit, or a similar quick attach coupling that allows the plunger  116  to be pushed and pulled. 
         [0053]    The syringe  114  defines at least one port for providing fluid flow communication with the pumping chamber  128 . In the particular embodiment illustrated, the syringe  114  includes two ports providing fluid flow communication with the pumping chamber  128 . Specifically, an inlet port  132  allows the pumping chamber  128  in the syringe  114  to be filled with contrast material, and purged of air through the inlet port  132 . A housing  134  circumscribes the inlet port  132  and allows the inlet port  132  to be connected with an appropriate bottle or bag  136  ( FIGS. 3 and 3B ) of contrast agent or saline. When the syringe  114  is oriented in a syringe holder  112  in an angiographic system as described above, the inlet port  132  is located above the pumping chamber  128 . 
         [0054]    The inlet port housing  134  is preferably clear because one aspect of the present invention provides a fluid detection device  76  ( FIG. 1 ) that is preferably operably connected to the housing  134 . The device ensures that all air has been purged from the syringe  114  and that fluid occupies the housing  134 . The fluid detection device may be embodied in a passive coating on the interior surface of the syringe that reacts when contacted by a fluid. Alternatively, the device may be embodied using an ultrasound, optic, or electromagnetic emitter to detect the presence of fluid in the housing  134 . One embodiment provides an optic sensor used to determine the position of a floating ball of a floating ball valve. When the ball is supported by fluid in an up position, any air in the syringe  114  has been purged. Though the syringe  114  shown in  FIGS. 4 and 5  is denoted as prior art, as mentioned above, the fluid detection device  76  is considered a novel aspect of the present invention. 
         [0055]    In this embodiment, the syringe  114  is mounted in an angiographic system at an angle such that any air bubbles present in the pumping chamber  128  migrate toward the inlet port  132 , through which they may be purged. To purge air through the inlet port  132 , the inlet port housing  134  houses a valve assembly that permits air to be expelled or purged from the syringe  114 , but does not allow fluid to flow out of the pumping chamber  128  and back into the bottle  136  of contrast fluid when pressure movement is applied on the syringe side of the check valve. Such a check valve is described in U.S. Pat. No. 6,099,502. 
         [0056]    The syringe  114  also includes an outlet port  138  in fluid flow communication with the pumping chamber  128 . The outlet port  138  permits fluid flow from the pumping chamber  128  to a fluid communication network, such as fluid network  20 . The outlet port  138  is surrounded, or circumscribed, by an outlet port housing  140  extending, or projecting, from the end wall of the syringe  114 . The outlet port housing  140  is constructed and arranged to receive a patient manifold connector tube  142  ( FIG. 1 ). 
         [0057]    The syringe body  114  is too large for use as a balloon inflation syringe. However, the syringe holder  112  is constructed and arranged specifically to hold a particular syringe body  114 . Thus, to place a balloon inflation syringe in the syringe holder and provide proper alignment with relation to the linear actuator  118 , and provide the necessary support needed to operate a relatively thin-walled balloon inflation syringe with a powerful linear actuator  118 , the present invention provides an adapter sleeve  120 , shown in  FIG. 3A  and in phantom in  FIG. 6 , constructed and arranged with outer dimensions that allow the sleeve  120  to be properly cradled by the syringe holder  112 . The inside cavity of the adapter sleeve is configured to closely mate with a balloon inflation syringe  104 . 
         [0058]    The balloon inflation syringe  104  is preferably closely analogous to the angiographic syringe  114 , to allow attachment of the balloon inflation syringe  104  to the injector subassembly  108 . Thus, the balloon inflation syringe  104  includes a wall that defines a pumping chamber  146  therein that is an appropriately small size to allow controlled balloon inflation, typically on the order of 5 ml to 40 ml. The syringe  104  also includes a plunger  148  that attaches to the linear actuator  118  in the same manner as the plunger  116  of the syringe  114 . An inlet port  150 , defined by an inlet port housing  152 , establishes fluid communication between the supply bottle  136  and the pumping chamber  146 . The inlet port housing  152  is longer than the analogous inlet port housing  134  of the angiographic syringe  114  to allow for the smaller diameter of the balloon inflation syringe  104 . An outlet port  154  defined by an outlet port housing  156 , establishes fluid communication between the patient manifold connector  142  and the pumping chamber  146  of the balloon inflation syringe  104 . 
         [0059]    Similar to the ports  132  and  138  of the angiographic syringe  114 , described above, the inlet port  150  and the outlet port  154  of the balloon inflation syringe  104  are located in upper portions and lower portions of the syringe  104  when the syringe  104  is loaded into the injector device  100 . However, as much less fluid is being injected, and it is very rare to inject all of the fluid located in the pumping chamber  146  during a balloon inflation procedure, there may be less importance placed on the location of the ports  150  and  154 . For example, the balloon inflation syringe  104  may be supplied pre-loaded with fluid, obviating the need for an inlet port  150 . Further, the outlet port  154  may be more conventionally located along a central axis of the syringe  104 , so long as the particular injection device  100 , to which the adapter sleeve  120  is designed, accommodates the placement of the outlet port  154 . 
         [0060]    Referring again to  FIGS. 3A and 6 , the adapter sleeve  120  is described in greater detail. The adapter sleeve  120  has an outer wall  158  defining an inner cavity  160  having an inside diameter substantially equal to the outside diameter of the balloon inflation syringe  104 . The outer wall  158  is open at a first end  162  and a second end  164  such that the balloon inflation syringe  104  may be loaded into the first end  162  and so that the linear actuator  118  may act on the plunger  148  of the syringe  104  through the second end  164 . The outer wall  158  also defines a groove  166  at the first end  162  that is constructed and arranged to accept the inlet port housing  152 .  FIG. 6  shows that when the syringe  104  is mated with the sleeve  120 , the size and shape of the resulting assembly is substantially the same as the size and shape of the angiographic syringe  114 . 
         [0061]      FIG. 7  shows an alternative embodiment of a balloon inflation device  170 . The balloon inflation device  170  is a self-contained unit that is attachable to an automatic injection device  102 . This arrangement obviates the need for switching syringes and inserting adapter sleeves when transitioning from a diagnostic imaging procedure to a balloon catheter procedure. Additionally, providing the balloon inflation device  170  as a self-contained unit allows for the use of common electronics and controls to be used for supplying power and commands to the mechanical components of the device  170 . 
         [0062]    The balloon inflation device  170  includes an appropriately sized syringe  172  operably attached to a linear actuator module  174 . The linear actuator module  174  contains an actuating device, such as a motor or hydraulic or pneumatic piston, useable to move a plunger  176  slideably disposed within the syringe  172 . 
         [0063]    The linear actuator module is able to receive and respond to commands given by the computer  106  of the automatic inflation device  102 , and receive the necessary power to drive the actuating device, through connector pins  178 . 
         [0064]    An advantage to providing a computer driven balloon inflation device, such as balloon inflation device  100  or  172 , is that the device can become integrated into a closed feedback loop that can be used to accurately achieve desired pressures within a balloon catheter during an inflation procedure. Referring back to  FIG. 1 , there is shown a pressure transducer  180  located within the fluid communication network  20  on the saline line  24 . The pressure transducer  180  is a sensitive instrument, capable of measuring small changes in pressure, such as those pertaining to biological patient attributes. Locating the pressure transducer  180  on the saline line  24  allows the patient manifold  22  to be used to insulate the transducer  180  from any high pressures that may be generated by the syringe  36 . 
         [0065]    A pressure sensor, such as the strain gauge  182 , shown in  FIG. 7 , can be used for high pressures, such as those developed by the balloon inflation syringe  104 . The strain gauge  182  is mounted to one of four syringe support rods  184  that are used to fix the syringe  172  to the linear actuator module  174 . Balloon pressure may be accurately determined by measuring the amount of strain encountered by the support rods  184  as the plunger  176  is depressed. Alternatively, pressure may be measured as a function of the load placed on the linear actuator module  174 . For example, if a DC motor is used to drive the linear actuator of the module  174 , a circuit may be incorporated into the electronics driving the motor that is constructed and arranged to measure motor torque as a function of current drawn. 
         [0066]    The feedback loop is formed by measuring balloon pressure and providing it to the computer  106 , which then uses it to increase or decrease the amount of pressure it instructs the linear actuator module  174  or linear actuator  118  to place on the plunger  176  or  148 , respectively. A significant advantage to forming a computerized feedback loop is the ability to load a program segment into the memory of the computer  106  that provides a target map to be used by the computer  106  for calculating error and determining corrective action. Another program segment can be used to create a display of target pressure and actual pressure, either numerically or graphically. 
         [0067]    Referring now to  FIGS. 8-10 , there are provided examples of displays  182  showing pressure versus time graphs  184  (units and values have been omitted but are understood to be included in an actual display). A similar graph may be provided for balloon volume versus time (not shown). 
         [0068]      FIG. 8  shows a display  182  with a graph  184  that may represent a typical balloon inflation pressure profile when a balloon is used to dilate an area in a blood vessel that has become restricted due to a build-up of plaque. At  186 , the balloon is inflating and pressure is rising steadily as the fluid meets with increasing resistance from the balloon and the walls of the vessel. The dotted line  188  represents the particular inflation characteristics of the balloon catheter being used in the procedure. This will be discussed in more detail below. 
         [0069]    Typically during this procedure, there will be a sudden drop in pressure  190 . This is known as a “pop” and it represents the plaque buildup giving way, the ultimate goal of the procedure. By breaking the bonds that hold the plaque together, the vessel is allowed to return to a diameter closer to that of its original size. When a balloon is being inflated manually, the physician pays attention to feeling this “pop” in the syringe being used to inflate the balloon. With the feedback loop of the present invention, a program segment is provided that allows the computer  106  to sense this “pop” and take a desired action thereafter. The graph in  FIG. 8  shows that the desired action in this case was to deflate the balloon at  192 . 
         [0070]      FIG. 9  shows a similar graph  184 . However, in this case, the desired action after the “pop” at  190  is to hold the pressure in the balloon constant at  192  for a predetermined period of time  194 . The feedback loop is thus used to move the plunger  148  appropriately to maintain a constant pressure in the balloon. 
         [0071]    It is not uncommon to encounter a clot that may be broken more than once as a balloon catheter stretches it.  FIG. 10  shows a graph  184  where a plurality of “pops” are encountered at  190   a ,  190   b , and  190   c . Here the program segment loaded into the computer  106  either specified a maximum pressure to be achieved, or a maximum volume to be achieved, given the pressure and volume limits of the balloon and/or the size constraints of the vessel. Alternatively, the program segment allows the device to be used in a manual mode, with safety limits set on pressure and volume. In manual mode the physician uses a hand control  196  ( FIG. 3 ) to control the inflation of the balloon, while viewing the display  182  for visual indication of the occurrence of a “pop” at  190 . Additional stimuli may be provided to the physician such as a tactile feedback mechanism, such as a vibration or a proportional force feedback, in the hand control  196 , or an audible tone provided by a speaker in the monitor  182 . Additionally, a program segment may be provided that allows a physician to inflate the balloon manually, while “recording” flow rates, volumes and pressures used, so that the computer  106  may “learn” how the physician inflated the balloon. The physician may then instruct the computer  106  to repeat the inflation techniques he or she just performed. There are many instances where multiple inflations must be performed and this feature allows the physician to replicate a desired inflation automatically. 
         [0072]      FIG. 8  shows a dotted line  188  that represents a baseline pressure profile of a particular balloon catheter in a no-load environment. One aspect of the present invention provides a bar code reader  198  ( FIG. 7 ), or similar data input device, that is useable to input a pressure profile. The balloon catheter manufacturer supplies the profile, preferably as a bar code on the catheter packaging, of the baseline no-load inflation characteristics of the balloon catheter contained therein. 
         [0073]    Knowing the baseline pressure characteristics of the balloon catheter allows the physician to view the difference between the actual, loaded pressure plot and the baseline graph  188 . The difference is attributed to the resistance to inflation exhibited by the blood vessel. 
         [0074]    The foregoing description addresses embodiments encompassing the principles of the present invention. The embodiments may be changed, modified and/or implemented using various types of arrangements. Those skilled in the art will readily recognize various modifications and changes that may be made to the invention without strictly following the exemplary embodiments and applications illustrated and described herein, and without departing from the scope of the invention, which is set forth in the following claims.