Abstract:
The invention of this application relates generally to intravenous (IV) infusion of drugs to patients, and more particularly to aspects of an IV infusion system comprising an infusate cassette and an infusate container. The present invention provides a drug infusion cassette that incorporates a strong vial spike that may be non-metal, a means for sheathing the spike when it is not in use, an anti-free flow device, and other beneficial features such as an air entrainment lockout mechanism, quality assurance tags, stopcocks made of soft materials and means of securing tubing to the cassette with a minimum of individual parts. The drug cassette can be used with an automated spiking mechanism comprising a motorized vial holder that holds a vial. The spike remains sheathed if the drug cassette is not fully engaged with a mating surface of devices such as a pumping unit or a sedation and analgesia delivery system.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional patent application Ser. No. 60/378,046, “Drug Container Entry Mechanisms,” filed May 16, 2002, which is hereby incorporated by reference. 
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable  
         REFERENCE TO A “MICROFICHE APPENDIX” 
         [0003]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    1. Field of the Invention  
           [0005]    The invention of this application relates generally to intravenous (IV) infusion of drugs to patients, and more particularly to aspects of an IV infusion system comprising an infusate cassette and an infusate container.  
           [0006]    2. Description of Related Art  
           [0007]    Mechanically controlled infusion of a liquid drug from a reservoir to a patient is a useful process of administering a drug. An electro-mechanically controlled infusion process often provides a much steadier and more accurate administration of a drug than is possible from a human giving injections. By letting a computer model determine flow rates of drug, an electro-mechanically controlled infusion device can be programmed such that the concentration of the drug at a patient&#39;s effect site compartment remains steadily within the drug&#39;s therapeutic range.  
           [0008]    Various medical devices for controlling the infusion of a liquid directly to a patient are known. Certain of these devices utilize pumping mechanisms to deliver liquid drugs from a reservoir such as a syringe, a collapsible bag, or a vial to a patient supply tube. One example of such a device, shown in U.S. Pat. No. 6,186,977, includes a liquid drug supply in a collapsible bag and an infusion pump, which draws the drug directly from the supply and moves it along a flow passage to a patient supply tube.  
           [0009]    Certain of these medical devices further utilize drug pump cassettes, which provide a rigid housing and pressure plate that interact with the pumping mechanisms of the devices. These cassettes serve as intermediary devices between drug containers and patient supply lines. A typical cassette includes a passage, which is acted upon by the pumping mechanism of an infusion device to move the drug along to the supply line.  
           [0010]    One example of a cassette for use with a drug pumping system, shown in U.S. Pat. No. 6,165,154, has a fluid passage and a collapsible pressure conduction chamber for generating a pressure gradient to move drug along the passage. Certain other cassettes are known which provide means for moving drug along a flow channel. One example of this other type of cassette, shown in U.S. Pat. No. 6,202,708, provides a large chamber for mixing a powdered drug with a liquid solvent. The cassette also includes a pressure plate, which supports a fluid flow passage against which a peristaltic pump may act to move the liquid along to a patient delivery tube.  
           [0011]    The above and other drug infusion cassettes generally have a sharp spike upon which a drug vial is impaled to provide access to the contents of the vial. Drug infusion cassettes that incorporate a sharp spike or trocar for penetrating a vial stopper may be considered as a sharp device, especially if the spike is exposed and able to cause an accidental sharps injury. The International Health Care Worker Safety Center has computed that 590,164 needlestick and sharps injuries occur annually in the United States. “Sharps” boxes are often employed to collect used sharp devices like needles and scalpels. A user drops a sharp device into a sharps box immediately after use to prevent accidental sharps injuries like needle sticks that may result in transmission of disease and blood-borne pathogens. Sharps boxes generally have a small opening that prevents a hand from being inserted into the sharps box, and may not accept larger devices such as drug infusion cassettes.  
           [0012]    Because drug cassettes are generally disposable and intended for single use, low manufacturing cost is desirable if an end product is to be competitive. Reduction of parts count may decrease inventory, cost of materials and assembly time, leading to lower manufacturing costs.  
           [0013]    In certain situations, a disposable drug cassette may be used on the same patient with more than one drug vial. In those situations where multiple vial spikings will occur, a spike on a drug cassette has to reliably withstand repeated forces and stresses imposed upon it by multiple spiking cycles.  
           [0014]    An ever-present concern with drug cassettes and drug infusion systems is “free flow” whereby drug in a vial, or residual drug in intravenous tubing, flows via gravity into a patient in an uncontrolled manner, especially in the case of potent drugs. Free flow of drugs is also possible even if a drug vial is not spiked on a cassette. Residual drug in an infusion line (peristaltic tubing and intravenous tubing) may flow by gravity to a still connected patient when a used cassette, without a vial, is being removed from a pumping unit. Air entrainment may also be possible in such a situation placing a patient at risk of air emboli in the bloodstream.  
           [0015]    If an intravenous (IV) set is disconnected at the cassette end after a drug infusion and the same IV set is subsequently used for infusing fluid to the same patient, residual drug trapped in the IV line, between the cassette end and the IV cannula end, will be infused to the patient first. In the case of potent drugs, the residual drug may produce unexpected consequences such as drowsiness and/or loss of consciousness. If the patient has been transported after the drug infusion, for example, for a sedation and analgesia procedure, to another location where no resuscitation personnel or equipment is available and/or functioning, an unplanned clinical emergency may occur that may place the patient at risk.  
           [0016]    Most IV infusion tubing sets use a manually-operated slide valve that is placed between a drug container end and an IV cannula end. A user of the infusion system has to remember to manually close the slide valve after an infusion so that free flow of residual drugs potentially followed by air entrainment does not occur upon disconnection of the IV line at the drug container end. If a slide clamp is placed upstream of the IV cannula end, then the slide valve, even if closed, cannot prevent air aspiration upon disconnection of the IV line at the IV cannula (patient) end. Thus, in conventional IV infusion tubing sets, disconnection at the IV cannula end would present a risk of air aspiration resulting in air emboli unless there is another stopcock or flow control component downstream at the IV cannula. A stopcock manufactured from a hard material such as plastic, when in close contact with a patient, may apply under certain circumstances, undue pressure to a patient&#39;s skin and tissues resulting in hypoperfusion, nerve injury or tissue damage.  
           [0017]    Some drug cassettes incorporate peristaltic tubing held in position next to a rigid pressure plate on the cassette. One end of the peristaltic tubing is in fluid connection to a vial mounted on the drug cassette and the other end of the peristaltic tubing is in fluid connection to intravenous tubing that delivers fluid to a patient. A pumping mechanism, usually external to a drug cassette, presses rhythmically on the peristaltic tubing to pump the vial content and control its flow rate to the patient. The peristaltic tubing has to be held in place against the drug cassette pressure plate for accurate pumping action. In some existing designs, this is done with multiple metal clips that increase parts count.  
           [0018]    Another potential failure mode during drug infusion may occur if peristaltic tubing is placed in the reverse orientation relative to a pumping unit, such that blood would be suctioned from a patient instead of drug being delivered to the patient. An indexing mechanism is generally used to prevent peristaltic tubing from being oriented in the reverse direction. This may be, for example, a mechanical part or component attached onto the peristaltic tubing with a corresponding, matching recess in a pumping unit when the peristaltic tubing is properly oriented. If the peristaltic tubing is improperly oriented, the mechanical indexing component will prevent mating of the peristaltic tubing to the drug cassette pressure plate and/or the pumping unit.  
           [0019]    Re-use of drug cassettes may lead to cross-contamination by blood-borne pathogens. Prevention of accidental or deliberate re-use of used and contaminated drug cassettes is desirable from the point of view of patient safety.  
           [0020]    Current vial entry mechanisms include metal spikes, such as, for example, metal-tipped spikes. Spikes that are designed for use with rigid walled containers like glass vials sometimes have two lumens, one for channeling flow of the vial content to a desired conduit and the other lumen for preventing buildup of vacuum above a meniscus of an inverted vial by allowing equilibration to atmospheric pressure.  
           [0021]    Metal, or metal-tipped, spikes generally require less force to pierce a given vial stopper than plastic spikes. For an automated or semi-automated vial spiking system, higher spiking forces usually required by a plastic spike may lead to unreliable spiking action and in case of repeated uses (multiple vials used with a single cassette), high spiking forces may lead to failure of a plastic spike.  
           [0022]    If a drug to be infused from a vial is capable of supporting bacterial growth such as the lipid emulsion used in propofol, a filter is used to trap airborne organisms and prevent them from entering into the vial, contaminating the drug, multiplying and harming a patient when the organisms are infused with the drug into the patient&#39;s bloodstream. The air filter generally comprises a filter media, a filter media holder and an external filter housing.  
         BRIEF SUMMARY OF THE INVENTION  
         [0023]    The present invention solves the aforementioned drawbacks of and needs from drug infusion devices by providing a drug infusion cassette that incorporates a strong vial spike that may be non-metal, a means for sheathing the spike when it is not in use, an anti-free flow device, and other beneficial features such as an air entrainment lockout mechanism, quality assurance tags, stopcocks made of, or shrouded in, soft materials and means of securing tubing to the cassette with a minimum of individual parts.  
           [0024]    More particularly, the present invention provides a drug cassette with a sheathed vial spike made of injection molded plastic with an automated free flow prevention feature. The drug cassette can be used with an automated spiking mechanism comprising a motorized vial holder that holds a vial. The spike remains sheathed if the drug cassette is not fully engaged with a mating surface of devices such as, for example, a pumping unit or a sedation and analgesia delivery system. In general, the vial will be upside down but the invention also contemplates the possibility of having the vial upright. The cassette of the present invention may include molded snap retainers or clips integral to the drug cassette in lieu of metal clips to hold peristaltic tubing in place, thus reducing parts count. A stopcock at the IV cannula or patient end, if present, is made of, or shrouded in, soft materials so that the risk of a pressure-induced injury is reduced.  
           [0025]    The present invention also provides a spike that can withstand the repeated stresses of multiple vial spikings and still be made of an inexpensive safe material such as injection molded plastic. Preferably, such a plastic spike of the present invention features a spiking force or peak spiking force that is similar to or less than that of a metal spike. The invention comprises different vial spike geometries, designed for injection molding manufacture, that minimize the force or peak force required to pierce a given vial stopper. An injection molded, sheathed vial spike may be less expensive to produce and easier and cheaper to dispose of, after use than an unsheathed metal or metal-tipped spike. An absence of sharp metal parts may mean that a sheathed, injection-molded spike can be safely discarded in contaminated wastebaskets, instead of a sharps box.  
           [0026]    The automated sheathing of the spike when a drug vial is not mounted to the drug cassette minimizes the risk of accidental sharps injury. The design provides tamper-resistant inaccessibility to the spike when the spike is not inserted in a vial, to further minimize risk of accidental sharps injury. When the vial entry mechanism and/or the cassette are made of plastic, the design of those elements is compatible with constraints imposed by injection molded tool design.  
           [0027]    In considering the mechanics of inserting a spike or vial entry device or trocar into a vial stopper, the force and/or peak force to insert a spike into a stopper comprises at least three major components: puncturing, tearing and cutting. Puncture is typically defined as a point propagation through a membrane that does not allow the elastic limits of a membrane or stopper to be compromised. Tearing is typically considered as point propagation that exceeds elastic limits. A membrane tears along stress planes (tear propagation) but sealing and multiple puncture characteristics of the membrane are not compromised. Cutting is typically defined as point propagation via a cutting edge before the elastic limits of a material are reached. A larger diameter results in a higher entry force and/or peak entry force, all other parameters being kept constant.  
           [0028]    A trocar design that primarily uses puncture and cutting actions will most likely produce low entry force and/or peak entry force. A tearing action requires greater forces due to friction as the trocar surface passes through tear planes. Cut propagation along with minimized cross-sectional area will promote low entry forces. However, cross-sectional area cannot be too small because a vial entry device needs to incorporate one or two lumens with a diameter of, for example, 0.040 inch along its length. A combination of two cutting surfaces at each end of the “stress-strain” points, along with least lateral movement (stretching) of membrane fibers making up a stopper appear to be most effective in reducing entry force and/or peak entry force.  
           [0029]    The invention includes a trocar exhibiting one or more than one of the following advantageous features aimed at reducing vial entry force and/or peak entry force: low cross-sectional area, a design that promotes puncture and cutting actions while minimizing lateral movement of membrane fibers, minimal or no tearing actions and a combination of two cutting surfaces at each end of the “stress-strain” points. The rate of change of cross-sectional area (A) with respect to distance from the tip (x) is expressed as dA/dx. Changes in dA/dx should be minimized, for example, no abrupt changes in cross-sectional area. The value of dA/dx should be kept low. A cutting or tearing edge is placed wherever there is a tendency to stretch so that the design promotes cutting and tearing rather than stretching.  
           [0030]    Upon removal of a vial from the drug cassette, a spike sheath re-deploys to sheath the spike. The movement of the spike sheath is used to actuate a lever arm that rotates a stopcock such that a drug lumen in a spike assembly is closed and drug flow is prevented. Thus, after a drug infusion, uncontrolled free flow of residual drug left in the peristaltic and intravenous tubing to a patient still connected to the drug cassette is prevented.  
           [0031]    A breakable fin on the drug cassette is used as an indicia of the use status of the drug cassette. The air filter housing is incorporated into a spike assembly to reduce parts count. A holder for the air filter media may also be incorporated in the spike assembly to further reduce parts count and manufacturing cost.  
           [0032]    The cassette is indexed to its mating surface by designing the cassette such that it can only mount onto its mating surface in one orientation.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]    [0033]FIG. 1 represents a trocar design where FIG. 1 a  is a plan view, FIG. 1 b  is a front view, FIG. 1 c  is a side view and FIG. 1 d  is a perspective view of the same trocar design;  
         [0034]    [0034]FIG. 2 represents a trocar design with a diamond cross-section where FIG. 2 a  is a plan view, FIG. 2 b  is a front view, FIG. 2 c  is a side view and FIG. 2 d  is a perspective view of the same trocar design;  
         [0035]    [0035]FIG. 3 represents an alternative embodiment of a trocar design where FIG. 3 a  is a plan view, FIG. 3 b  is a front view, FIG. 3 c  is a side view and FIG. 3 d  is a perspective view of the same trocar design;  
         [0036]    [0036]FIG. 4 represents a trocar design with a diamond cross-section where FIG. 4 a  is a plan view, FIG. 4 b  is a front view, FIG. 4 c  is a side view and FIG. 4 d  is a perspective view of the same trocar design;  
         [0037]    [0037]FIG. 5 represents a trocar design with a stretched hexagon cross-section where FIG. 5 a  is a plan view, FIG. 5 b  is a front view, FIG. 5 c  is a side view and FIG. 5 d  is a perspective view of the same trocar design;  
         [0038]    [0038]FIG. 6 represents a trocar design with a football shaped cross-section where FIG. 6 a  is a plan view, FIG. 6 b  is a front view, FIG. 6 c  is a side view and FIG. 6 d  is a perspective view of the same trocar design;  
         [0039]    [0039]FIG. 7 represents yet another trocar design where FIG. 7 a  is a plan view, FIG. 7 b  is a front view, FIG. 7 c  is a side view and FIG. 7 d  is a perspective view of the same trocar design;  
         [0040]    [0040]FIG. 8 represents a trocar design with an ogival cross-section where FIG. 8 a  is a plan view, FIG. 8 b  is a front view, FIG. 8 c  is a side view and FIG. 8 d  is a perspective view of the same trocar design;  
         [0041]    [0041]FIG. 9 depicts a perspective view of a drug cassette with integral spike sheathing and anti-free flow features;  
         [0042]    [0042]FIGS. 10 a  and  10   b  show different perspective views of a spike assembly with an integrated stopcock lever arm that interacts with a drug cassette;  
         [0043]    [0043]FIG. 11 is a cut-out view of a spike assembly attached to a drug cassette with a spike sheath omitted;  
         [0044]    [0044]FIG. 12 is a perspective bottom view of a spike sheath;  
         [0045]    [0045]FIGS. 13 a  and  13   b  represent perspective cut-out views of an anti-free flow device on a spike assembly interacting with protuberances on a spike sheath, in sheathed and exposed positions respectively;  
         [0046]    [0046]FIG. 14 shows a perspective view of a drug cassette and a mating surface when the two are not yet touching;  
         [0047]    [0047]FIG. 15 shows a perspective view of interaction between a drug cassette and a mating surface when the two are partially engaged; and  
         [0048]    [0048]FIG. 16 shows a perspective view of interaction between a drug cassette and a mating surface when the two are engaged and mated. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0049]    U.S. patent application Ser. Nos. 09/324,759, filed Jun. 3, 1999 and 10/208,184, filed Jul. 31, 2002, both hereby incorporated herein by reference, disclose and enable several embodiments of an infusion administration device having various aspects including a cassette for the transfer of infusion liquid from a sealed drug container to a patient having a rigid pressure plate, a drug flow activation device for initiating the transfer of the infusion liquid from the drug container to the device where the device may be a spike for piercing a resealable stopper of a drug container, free-flow prevention devices, and air-entrainment lockout mechanisms, among other aspects. The embodiments of the trocar and cassette of the present invention as described below are meant to be adapted to work with such a device as well as with most other automated liquid infusion devices.  
         [0050]    The different spike designs described below may be manufactured of plastic by injection molding. The plastic may be subsequently hardened by annealing or other processes used to harden or cure plastic.  
         [0051]    In spike designs where lumen openings at or near a spike tip are at different elevations, the upper lumen opening may preferably be used for venting while the lower lumen opening may preferably be used for channeling the content of a spiked container. This ensures less wastage of the infusion liquid by increasing the amount of liquid in a vial that can be infused before the meniscus gets too close to the drug flow lumen opening. That is, a lower lumen opening will keep on channeling the vial content if the meniscus is below an upper lumen opening and above the lower lumen opening. Conversely, a higher lumen opening might preferably be used for an atmospheric vent so that the atmospheric vent is beneath the infusion liquid meniscus for a shorter time.  
         [0052]    The lumens are shown in FIGS.  1 - 8  as circular lumens because circular lumens may be easier to injection mold but the lumens do not necessarily need to be circular. They could instead be oval or some other non-circular shape that minimizes the aspect ratio, area or profile of the spike cross-section. The lumens do not necessarily need to each be of the same diameter and/or shape as they accomplish different functions. A venting lumen channels air into a vial to relieve vacuum while a drug flow lumen channels liquid content out of the vial.  
         [0053]    The bevels are shown as plane surfaces in FIGS.  1 - 8  but could also be concave and/or convex surfaces in all the different designs described below. Reduction of the cross-sectional area by removing features such as pointed edges from a football shape and replacing them with blunter semi-circles does not seem to reduce the peak vial entry force even though the overall cross-sectional area has been decreased. The peak entry force appears to occur at the point of maximum spread or stretching of the stopper material.  
         [0054]    [0054]FIG. 1 shows a spike or trocar design with a cross-sectional shape that looks like an athletic track (a rectangle with equal semi-circles replacing two opposite sides of the rectangle). The cross-section shown in FIG. 1 a  is large enough to accommodate one or more lumens  14 , e.g., of 0.03″-0.04″ diameter. The lumens  14  do not need to be of equal diameter and/or shape although they are shown with identical diameters and shapes. If two lumens are present, the centers of the lumens have a spacing  11 , which may, for example, be in the range between 0.06″-0.08″. The cross-section of the spike has a thickness  12 , which may, for example, be 0.08″ wide with the centers for the 0.08″ diameter semi-circles spaced for example, 0.06″-0.08″ apart. The centers of the lumens and the semi-circles happen to be coincident in FIG. 1 a  but do not necessarily need to be so. The cross-section has a width  10  which may, for example, be in the range of 0.14″-0.16″. In FIG. 1 a , the center of the left lumen is at a distance  13  from the left edge of the cross-section where  13  may, for example, be 0.04″. The centers of the lumens  14  do not necessarily need to be symmetrically laid onto the cross-section of the spike but may instead be offset. The cross-section does not necessarily need to be symmetrical. For example, the semi-circle on the right side of FIG. 1 a  may have a different diameter than that on the left side. Similarly, the top and bottom sides of the shape shown in FIG. 1 a  do not necessarily need to be parallel but could instead produce a taper (see, for example, FIG. 3 a ).  
         [0055]    The spike has a bevel  15  across its entire cross-section at an angle  16  from the horizontal (FIG. 1 b ). For example, the bevel angle  16  could be 70°-80° with the actual angle shown in FIG. 1 b  being 75°. Additional bevels  17  at an angle  18  to the horizontal may be added at the tip to provide a sharper point to the spike tip (FIG. 1 e ). The angle  18  may be, for example, 70°-80° with the actual angle shown in FIG. 1 c  being 75°. The additional bevels  17  may or may not join together at the tip and may not necessarily be symmetrical. In FIG. 1 c , the bevels  17  are shown as symmetrical and joining at the tip. Bevel  15  is shown as a non-skewed cut in FIG. 1, in the sense that corresponding points on the top and bottom straight edges in FIG. 1 a  are at the same elevation when the spike is upright or vertical. Bevel  15  may be skewed, instead of level, such that FIG. 1 c  becomes asymmetric even if the cross-section in FIG. 1 a  is symmetrical.  
         [0056]    [0056]FIG. 2 represents an alternative spike design with a diamond cross-section incorporating one or more lumens  14 , e.g., of 0.03″-0.04″ diameter. The lumens  14  do not need to be of equal diameter and/or shape although they are shown with identical diameters and shapes. If two lumens  14  are present, the centers of the lumens have a spacing  21 , which may, for example, be 0.07″-0.08″ along the shorter axis  22 . Alternatively, the centers of the two lumens may be aligned along the long axis  20  as shown in FIG. 2 a . The shorter axis  22  maybe, for example 0.15″ long and the longer axis  20  maybe, for example, 0.188″ long. In some embodiments of the design, the long axis  20  and the short axis  22  may be identical such that the diamond cross-section becomes a square cross-section. In FIG. 2 a , the center of the left lumen is at a distance  23  from the left edge of the cross-section where  23  may, for example, be 0.054″. The centers of the lumens  14  do not necessarily need to be symmetrically laid onto the cross-section of the spike but may instead be offset. The diamond cross-section does not necessarily need to be symmetrical. For example, the pointed edge on the right side of FIG. 2 a  may be at a different angle and distance from the centerline compared to the left edge.  
         [0057]    A large bevel  25  across the entire cross-section at an angle  26  from the horizontal, in combination with the diamond cross-section, produces the spike tip (FIG. 2 b ). For example, the angle  26  may be 70°-80° with the actual angle shown in FIG. 2 b  being 75°. Additional bevels  27  at an angle  28  to the horizontal, may be added at the sides of the spike (FIG. 2 c ). The angle  28  may be, for example, 91°-95° with the actual angle shown in FIG. 2 c  being 93°. The bevels  27  are started at a distance  30  from the tip of the spike. Distance  30  may be, for example, 0.827″. The additional bevels  27  may or may not join together at the tip and may not necessarily be symmetrical. In FIG. 2 c , the bevels  27  are shown as symmetrical but not joining at the tip. Bevel  25  is shown as a non-skewed cut in FIG. 2. Bevel  25  may be skewed, instead of level, such that FIG. 2 c  becomes asymmetric even if the cross-section in FIG. 2 a  is symmetrical.  
         [0058]    [0058]FIG. 3 represents yet another alternative spike design with a cross-section incorporating one or more lumens  14 , e.g., of 0.03″-0.04″ diameter, where the short ends of a trapezoid are replaced by semi-circles  34 ,  36  of unequal diameter. The lumens  14  do not need to be of equal diameter and/or shape although they are shown with identical diameters and shapes. If two lumens  14  are present, the centers of the lumens have a spacing  38  which may, for example, be 0.065″. One semi-circle  36  may be, for example, of 0.08″ diameter with the other semi-circle  34  at, for example, 0.07″ diameter (FIG. 3 a ). The entire width  39  of the cross-section maybe, for example, 0.14″. The lumen at the narrower semi-circle  34  may be narrower, e.g., of 0.03″ diameter. The distance  33  from the center of the left lumen to the left edge in FIG. 3 a  may, for example, be 0.04″. The centers of the lumens  14  do not necessarily need to be symmetrically laid onto the cross-section of the spike but may instead be offset. The centers of the lumens  14  and the semi-circles  34 ,  36  happen to be coincident in FIG. 3 a  but do not necessarily need to be so.  
         [0059]    A large bevel  41  at an angle  40  to the horizontal is made across the entire cross-section (FIG. 3 b ). For example, the bevel angle  40  may be 70°-80° with the actual angle shown in FIG. 3 b  being 75°. Additional bevels  43  at an angle  42  to the horizontal may be added at the tip to provide a sharper point to the spike tip (FIG. 3 c ). The angle  42  may be, for example, 70°-80° with the actual angle shown in FIG. 3 c  being 75°. The additional bevels  43  may or may not join together at the tip and may not necessarily be symmetrical. In FIG. 3 c , the bevels  43  are shown as symmetrical and joining at the tip. Bevel  41  is shown as a non-skewed cut in FIG. 3, in the sense that corresponding points on the top and bottom edges in FIG. 3 a  are at the same elevation when the spike is upright or vertical. Bevel  41  may be skewed, instead of level, such that FIG. 3 c  becomes asymmetric even if the cross-section in FIG. 3 a  is symmetrical.  
         [0060]    [0060]FIG. 4 represents still another spike design with a diamond cross-section incorporating one or more lumens  14 , e.g., of 0.03″-0.04″ diameter. The lumens  14  do not need to be of equal diameter and/or shape although they are shown with identical diameters and shapes. If two lumens are present, the centers of the lumens have a spacing  45 , which may for example, be 0.08″ apart along the shorter axis  46 . The shorter axis  46  may be, for example 0.16″ long and the longer axis  44  may be, for example, 0.2″ long. In some embodiments of the design, the long axis  44  and the short axis  46  may be identical such that the diamond cross-section becomes a square cross-section. The centers of the lumens may also be aligned along the long axis  44  as shown in FIG. 4 a  and the distance  45  between the lumen centers may be, for example, 0.057″. The distance  47  from the center of the left lumen to the left edge in FIG. 4 a  may, for example, be 0.094″. The centers of the lumens  14  do not necessarily need to be symmetrically laid onto the cross-section of the spike but may instead be offset. In FIG. 4 a , the lumens are purposely offset to the right so that the intersection of the lumens with the bevels  49  and  51  do not create “hooks” on which the stopper material might snag, thus generating or requiring a higher vial entry force. The diamond cross-section does not necessarily need to be symmetrical. For example, the pointed edge on the right side of FIG. 4 a  may be at a different angle and distance from the centerline compared to the left edge.  
         [0061]    A large bevel  49  at an angle  50  to the horizontal is made across the entire cross-section (FIG. 4 b ). For example, the bevel angle  50  may be 70°-80° with the actual angle shown in FIG. 1 c  being 75°. Additional bevels  51  may be added starting at a distance  52  from the tip and joining together at the tip to provide a sharper point to the spike tip (FIG. 4 c ). Distance  52  may, for example, be 1.051″. The additional bevels  51  may or may not join together at the tip and may not necessarily be symmetrical. In FIG. 3 c , the bevels  51  are shown as symmetrical and joining at the tip. Bevel  49  is shown as a non-skewed cut in FIG. 4. Bevel  49  may be skewed, instead of level, such that FIG. 4 c  becomes asymmetric even if the cross-section in FIG. 4 a  is symmetrical.  
         [0062]    [0062]FIG. 5 depicts a spike with a stretched hexagonal cross-section incorporating one or more lumens  14 , e.g., of 0.03″-0.04″ diameter. The lumens  14  do not need to be of equal diameter and/or shape although they are shown with identical diameters and shapes (FIG. 5 a ). If two lumens are present, the centers of the lumens have a spacing  58 , which may be, for example, 0.07″ along the long axis  54 . The short axis  56  of the hexagon may be, for example, 0.08″ long and the long side or axis  54  may be, for example, 0.16″ long. The distance  57  from the center of the left lumen to the left edge in FIG. 5 a  may, for example, be 0.045″. The centers of the lumens  14  do not necessarily need to be symmetrically laid onto the cross-section of the spike but may instead be offset. The stretched hexagonal cross-section does not necessarily need to be symmetrical. For example, the pointed edge on the right side of FIG. 5 a  may be at a different angle and distance from the centerline compared to that on the left side. Similarly, the top and bottom sides of the hexagon shown in FIG. 5 a  do not necessarily need to be parallel but could instead produce a taper.  
         [0063]    A large bevel  61  at an angle  62  to the horizontal, is made across the entire cross-section (FIG. 5 b ). For example, the angle  62  may be, for example, 70°-80° with the actual angle shown in FIG. 5 b  being 75°. Bevel  61  is shown as a non-skewed cut in FIG. 5, in the sense that corresponding points on the top and bottom straight edges in FIG. 5 a  are at the same elevation when the spike is upright or vertical. Bevel  61  may be skewed, instead of level, such that FIG. 5 c  becomes asymmetric even if the cross-section in FIG. 5 a  is symmetrical.  
         [0064]    [0064]FIG. 6 illustrates a spike with a football shaped cross-section incorporating one or more lumens  14 , e.g., of 0.03″-0.04″ diameter. The lumens  14  do not need to be of equal diameter and/or shape although they are shown with identical diameters and shapes (FIG. 6 a ). If two lumens are present, the centers of the lumens  14  have a spacing  65 , which may, for example, be 0.07″ apart along the long axis  64  which may, for example, be 0.188″ long. The thickness  66  of the cross-section may, for example, be 0.05″-0.08″. The distance  67  from the center of the left lumen to the left edge in FIG. 6 a  may, for example, be 0.059″. The centers of the lumens  14  do not necessarily need to be symmetrically laid onto the cross-section of the spike but may instead be offset. The football shaped cross-section does not necessarily need to be symmetrical. For example, the pointed edge on the right side of FIG. 6 a  may be at a different angle and at a different distance from the midline compared to the left side. Similarly, the top and bottom sides of the football shape shown in FIG. 6 a  do not necessarily need to be symmetrical but could instead have different radii.  
         [0065]    A large bevel  69  at an angle  70  to the horizontal across the entire cross-section is used to generate the tip (FIG. 6 b ). For example, angle  70  may be 70°-80° with the actual angle shown in FIG. 6 b  being 75°. Bevel  69  is shown as a non-skewed cut in FIG. 6, in the sense that corresponding points on the top and bottom edges in FIG. 6 a  are at the same elevation when the spike is upright or vertical. Bevel  69  may be skewed, instead of level, such that FIG. 6 c  becomes asymmetric even if the cross-section in FIG. 6 a  is symmetrical.  
         [0066]    [0066]FIG. 7 is a graphical representation of a spike with a cross-sectional shape that looks like an athletic track (a rectangle with a semi-circle replacing each short end). The cross-section is large enough to accommodate one or more lumens  14 , e.g., of 0.03″-0.04″ diameter. The lumens  14  do not need to be of equal diameter and/or shape although they are shown with identical diameters and shapes (FIG. 7 a ). If two lumens are present, the centers of the lumens have a spacing  75 , which may be, for example, 0.07″. The cross-section of the spike has a thickness  76 , which may, for example, be 0.08″ with the centers for the semi-circles spaced, for example, 0.07″ apart. The centers of the lumens and the semi-circles happen to be coincident in FIG. 7 a  but do not necessarily need to be so. The long axis  74  may be, for example, 0.15″ long. In FIG. 7 a , the center of the left lumen is at a distance  77  from the left edge of the cross-section where  77  may, for example, be 0.04″. The centers of the lumens  14  do not necessarily need to be symmetrically laid onto the cross-section of the spike but may instead be offset. The cross-section does not necessarily need to be symmetrical. For example, the semi-circle on the right side of FIG. 7 a  may have a different diameter than that on the left side. Similarly, the top and bottom sides of the shape shown in FIG. 7 a  do not necessarily need to be parallel but could instead produce a taper (see, for example, FIG. 3 a ).  
         [0067]    Two symmetrical bevels  79  join at the midline to form a tip at an angle  80  to the horizontal (FIG. 7 b ) and generate a line at an angle  82  to the horizontal (FIG. 7 c ). Angle  80  might be, for example, 60°-70° whereas angle  82  might be 65°. Bevels  79  are shown as symmetrical but do not necessarily need to be so.  
         [0068]    [0068]FIG. 8 is a drawing of a spike design with a semi-ogival cross-section with a thickness  90  and a width  88 . A semi-circle  95  which may be, for example, of 0.08″ diameter is at one end of the cross-section. The other end of the cross-section is composed of an ogive  97 . Thickness  90  may be, for example, 0.08″. The long axis or width  88  of the cross-section may be, for example, 0.169″ long (FIG. 8 a ). Ogive  97  may be for example, 0.08″ thick and 0.094″ long when measured from the midpoint between the two lumen centers. The two curves of the ogive  97  are composed of segments of circles with a radius of, for example, 0.104″. The ogive  97 , although shown as symmetrical does not necessarily need to be symmetrical. The two curves of the ogive  97  could be from segments of circles of different radii. The cross-section is large enough to accommodate one or more lumens  14 , e.g., of 0.03″-0.04″ diameter. The lumens  14  do not need to be of equal diameter and/or shape although they are shown with identical diameters and shapes (FIG. 8 a ). If two lumens are present, the centers of the lumens have a spacing  94 , which may, for example, be 0.07″. In FIG. 8 a , the center of the left lumen is at a distance  93  from the left edge of the cross-section where  93  may, for example, be 0.059″. The centers of the lumens  14  do not necessarily need to be symmetrically laid onto the cross-section of the spike but may instead be offset. The cross-section does not necessarily need to be symmetrical. For example, the middle of the top and bottom sides of the shape shown in FIG. 8 a  do not necessarily need to be parallel but could instead produce a taper.  
         [0069]    A large bevel  103  at an angle  98  to the horizontal and another smaller bevel  101  at an angle  100  to the horizontal combine to make a point (FIG. 8 b ). The bevel angles  98 ,  100  may, for example, be equal at 70°-80° but may also be of unequal values. The actual bevel angle  98 ,  100  shown in FIG. 8 b  is 75°. The smaller bevel  101  may start, for example, at a distance  99  from the tip, which may, for example, be 0.075″. Two small additional bevels  105  at an angle  102  to the horizontal are used to generate a sharper tip. Angle  102  may be, for example, 70°-80° with the actual angle shown being 75°. The bevels  105  may or may not be symmetrical even though they are shown as symmetrical in FIG. 8 c . Bevels  101 ,  103  are shown as non-skewed cuts in FIG. 8, in the sense that corresponding points on the top and bottom edges in FIG. 8 a  are at the same elevation when the spike is upright or vertical. Bevels  101 ,  103  may be skewed, instead of level, such that FIG. 8 c  becomes asymmetric even if the cross-section in FIG. 8 a  is symmetrical.  
         [0070]    The large bevel  103  by itself would have been sufficient to create a sharp pointed tip when intersecting with the cross-section in FIG. 8 a . However, the tip might then be too thin and pointy and might be susceptible to bending and breakage. A smaller bevel, like bevel  101 , opposed to bevel  103 , serves to make the tip stronger and less susceptible to bending.  
         [0071]    [0071]FIG. 9 shows a perspective view of a particular embodiment of a drug cassette  150  according to the present invention having a pressure plate  152 . Pressure plate  152  may include molded snap retainers  154  or other such means of holding peristaltic tubing (not shown for clarity) in place against the plate. A peristaltic pumping mechanism may be provided with the device that contacts the tubing and works on it against the pressure plate. Cassette body  156  may contain a cavity  176  (shown in FIG. 11) that receives a slidably mounted spike sheath  158  that is shown in a deployed position in FIG. 9. Spike body  156  is constructed so as to allow spike sheath  158  to slide down and expose a spike  163  if drug cassette  150  is fully engaged with mating surface  200  (FIG. 14) of the device and is also constructed so as to not allow sheath  158  to slide down if cassette  150  is not fully engaged with surface  200 . In particular embodiments of this invention, then, when a new or used drug cassette  150  is not mounted to mating surface  200 , vial sheath  158  will always be deployed to sheath spike  163  and prevent accidental sharps injury. The cassette  150  may then be disposed in a contaminated wastebasket after use with minimized concern about a potential for accidental sharps injury by an exposed spike. A groove  192  may be included on both spike sheath  158  and cassette body  156  to provide clearance for peg  202  of surface  200  that fits into groove  192 . A breakable fin may be provided on cassette  150  to act as an indicia of use status of drug cassette  150 . The top of drug cassette  150  may be constructed with contoured ridges that provide a better grip for handling the cassette.  
         [0072]    [0072]FIG. 10 a  is a perspective view of an embodiment of a spike assembly  160  which may be fitted to cassette  158  and to the peristaltic tubing. Spike assembly  160  includes spike  163  and may include any or all of air filter housing  162 , tapered outlet connector  164  for connection to the peristaltic tubing and lever arm  166  or other means for actuating a stopcock  168  (FIG. 10 b ). Spike  163  may include lumens  14   a  (air venting lumen) and  14   b  (drug flow lumen). Air flows via lumen  14   a  into a vial when placed over spike assembly  160  and spiked. This air flow may prevent vacuum buildup inside a vial when the vial contents are emptied during infusion. Air filter housing  162  may house a filter element (not shown) that filters out airborne disease organisms from the ambient air that flows into the vial via lumen  14   a . Air filter housing  162  may be designed so as to eliminate the use of an air filter media holder that is traditionally used to contain the air filter media, further reducing parts count and cost of manufacture for the apparatus of the present invention. When lever arm  166  is in the up position as is shown in FIGS. 10 a  and  10   b , stopcock  168  is rotated such that drug lumen  14   b  is closed. A closed drug lumen  14   b  prevents free flow of residual drug left in peristaltic and intravenous set tubing and prevents potential entrainment of air emboli into the patient&#39;s bloodstream in situations where a used drug cassette  150  is removed from mating surface  200  while the intravenous set tubing is still connected to a patient. Spike  163  is shown as one particular shape in the spike assembly figures but may be of any shape, including those described in FIGS.  1 - 8 .  
         [0073]    [0073]FIG. 11 depicts a cut-out perspective view of drug cassette body  156  with spike sheath  158  removed. A cavity  176  in drug cassette body  156  is designed to accept spike sheath  158  (not shown). Spike assembly  160  (FIG. 10) is attached to a mounting flange  170  which is incorporated in or itself attached to drug cassette body  156 . Mounting flange  170  holds spike assembly  160  stationary relative to drug cassette body  156 , especially along a vertical axis such that a vial may be pushed onto spike assembly  160 . A movable member  172  forms part of the wall of cavity  176  and may be made movable by slits  178  cut below and above member  172 . Member  172  may have a groove  192  having end  174 . Peg  175  on movable member  172  engages with a notch  184  or other surface of spike sheath  158 . Movable member  172 , when in a normal resting, or retracted, position, engages notch  184  (FIGS. 14 and 15) in spike sheath  158  with peg  175  thereby preventing vertical movement of spike sheath  158 . When movable member  172  is in a deployed position, peg  175  no longer engages notch  184  (FIG. 16), thereby allowing vertical displacement of spike sheath  158 . Movable member  172  is deployed when drug cassette  150  is substantially engaged with mating surface  200 . A peg  202  may be mounted on mating surface  200  in a position so as to deploy movable member  172  by pushing on end  174  of groove  192 , when cassette  150  is placed against mating surface  200 .  
         [0074]    Vertical displacement of spike sheath  158  allows for each or both of the sheathing and unsheathing of spike  163  and the activation or deactivation of an anti-free flow device. For example, when sheath  158  is in an up position, spike  163  is sheathed by spike sheath  158  and a stopcock  168  is closed thereby preventing free flow of infusion liquid through spike assembly  160 . When sheath  158  is in a down position, spike  163  is unsheathed and stopcock  168  is open thereby allowing the flow of infusion liquid through the spike assembly  160 .  
         [0075]    [0075]FIG. 12 shows a perspective view of spike sheath  158  which may include portion  190 , opening  188  to let spike  163  go through spike sheath  158  and protuberances  182  and  186  that engage with lever arm  166  to close and open stopcock  168  respectively as spike sheath  158  travels up and down (FIGS. 13 a  and  13   b ). At the top of portion  190 , a step  180  may be provided with a lip  191  that engages with a vial holder (not shown).  
         [0076]    In a particular embodiment, the vial holder engages with step  180  and lip  191  of spike sheath  158  as cassette  150  is engaged to mating surface  200 . As movable member  172  is deployed to allow downwards travel of spike sheath  158 , the vial holder engages with spike sheath  158  to prevent unplanned downwards travel of spike sheath  158 . When the vial holder and spike sheath are interlocked, the spike sheath cannot travel down if the vial holder is not traveling down. Therefore, in such an embodiment, it is not possible to manually depress the spike sheath and expose the spike, when the cassette is fully engaged to its mating surface.  
         [0077]    The vial holder is presented to the spike assembly with an inverted vial to be spiked when the vial holder moves down against the spike sheath  158 . If there is no vial in the vial holder, downwards travel of the vial holder may then expose the spike, posing a risk of a sharps injury. Particular embodiments of the invention check for the presence of a vial before initiating downwards travel of the vial holder. Checking for the presence of a vial may be implemented with sensors, including Quality Assurance Modules (QAM) such as those described in U.S. patent application Ser. No. 10/252,818 filed Sep. 24, 2002 and/or software or via mechanical means. The invention may also check if the vial is valid, e.g., of known origin and quality control and not past its expiry date. When the vial holder moves down, spike  163  is unsheathed through opening  188  and pierces the vial stopper thereby placing lumens  14   a  and  14   b  inside the inverted vial. The vial holder may engage the lip  191  and step  180  of spike sheath  158  such that when the vial holder moves up to unspike a vial, the vial holder drags spike sheath  158  upwards and re-sheaths spike  163 . A cut-out  194  in spike sheath  158  may be included to provide clearance for mounting flange  170  when spike sheath  158  travels downwards. A groove  192  on portion  190  may be provided with groove  192  of movable member  172  so as to accept edge  204  of peg  202  that is provided with mating surface  200  (FIG. 14). Edges  189  on both sides of portion  190  prevent spike sheath  158  from rotating within cavity  176  such that spike sheath  158  is only free to move in a vertical axis. Edges  189  also act as guides for vertical travel of spike sheath  158 . FIG. 13 a  shows how spike sheath  158  deploys upwards to sheath spike  163  while protuberance  182  engages with lever arm  166  to close stopcock  168  thus preventing flow in drug lumen  14   b  of spike  163 . FIG. 13 b  shows how spike sheath  158  retracts downwards to expose spike  163  while protuberance  186  engages with lever arm  166  to open stopcock  168  thus allowing flow in drug lumen  14   b  of spike  163 . FIG. 14 shows part of drug cassette body  156  oriented for engagement with mating surface  200  but not yet contacting the surface. Peg  202  includes edge  204  that slides along groove  192  on drug cassette body  156  and on portion  190  of spike sheath  158 . Peg  202  may also include a protuberance  206  that abuts against end  174  to deploy movable member  172  when drug cassette  150  is fully engaged with mating surface  200 . Protuberance  206  travels along groove  192 . A cutout behind protuberance  206  on peg  202  may be included to allow spike sheath  158  to travel downwards without catching on peg  202 . FIG. 15 shows part of drug cassette body  156  partially engaged with mating surface  200 . Rounded edge  204  of protuberance  206  of peg  202  is shown engaged in groove  192  on portion  190 . Spike sheath  158  is still prevented by movable member  172  from moving downwards and exposing spike  163 . The vial holder (not shown) is engaging step  180  and lip  191  of the spike sheath. FIG. 16 shows drug cassette body  156  substantially engaged with mating surface  200  so as to deploy movable member  172 . Protuberance  206  of peg  202  is shown engaged in end  174  of groove  192  on drug cassette body  156 . Movable member  172  is deployed allowing spike sheath  158  to move downwards and expose spike  163 .  
         [0078]    It is contemplated that a drug cassette  150  may be provided as part of a kit of disposable elements for use with a vial infusion system such as that described in U.S. patent application Ser. No. 09/324,759, filed Jun. 3, 1999. The cassette may also be provided alone as a disposable or reusable component of a vial infusion system. To enhance safety and to prevent accidental injury from spike  163 , it is contemplated that the drug cassette  150  of the present invention may be unpacked from a kit or other packaging or storing material with spike sheath  158  in an up or deployed position so that spike  163  is not exposed. Drug cassette  150  may be secured to mating surface  200  by an automated mechanism (not shown) or manually. A drug vial (not shown) that is loaded upside down onto a vial holder (not shown) may then be positioned in place over the spike assembly  160  and against the spike sheath  158 . The vial holder is constructed so as to position the vial so that the vial stopper is aligned and centered with spike sheath  158 . The vial holder may also engage with lip  191  of spike sheath  158  and drives the vial and spike sheath downwards exposing spike  163  and piercing the vial stopper. The vial holder may be positioned above spike sheath  158  and moved down by an automated means provided with the infusion system. As spike sheath  158  travels downwards, lever arm  166  is actuated such that stopcock  168  or other anti-free flow device allows flow of the liquid in the vial through drug lumen  14   b . Drug cassette  158  and the peristaltic and intravenous tubing (IV) may then be purged, the IV tubing connected to an IV catheter, and an infusion process to a patient begun in a manner such as that described in U.S. patent application Ser. No. 10/285,689 filed Jul. 31, 2002 and incorporated herein by reference.  
         [0079]    At the end of an infusion case, drug infusion is stopped. The vial holder is pulled up and as it moves up it pulls the vial up and drags spike sheath  158  along with its lip  191 . The upwards travel of spike sheath  158  triggers lever arm  168  closing off drug lumen  14   b . As the vial is unspiked, then, spike  163  is resheathed. Once the vial is removed, drug cassette  158  can be disengaged from mating surface  200 . Because drug lumen  14   b  is closed, none of the residual drug left in drug cassette  158  and IV tubing can free flow to a patient still connected to the IV tubing. The IV tubing may then be disconnected from the IV catheter. The intravenous tubing and drug cassette  150  with the spike assembly  160  may then be discarded in a contaminated wastebasket.  
         [0080]    If more than one vial is required for a given case, a first vial may be unspiked as described above while leaving drug cassette  150  secured to mating surface  200 . Closed drug lumen  14   b  prevents aspiration of air into the peristaltic and IV tubing such that there is no need to purge or prime the IV and/or peristaltic tubing again after changing vials. A new vial may then be loaded in the vial holder and spiked as described above. The vials can be changed in this manner as many times as needed until a case is concluded.