Abstract:
A drug infusion system is capable of delivering a fluid medication consisting of a plurality of drug to a patient under direction of a medical professional. The device is programmed to deliver a primary drug in a prescribed dose. The device determines the resultant dose of a secondary drug and displays such resultant dose to the medical professional. Dual sets of memory for storing operating parameters are alternatively active.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to drug infusion systems and, in particular, drug infusion systems that are programmable by a medical professional.  
         BACKGROUND OF THE INVENTION  
         [0002]    Drug infusion systems dispense fluid medication, containing a drug, to a patient. Some drug infusion systems are portable, allowing a patient to receive fluid medication while remaining mobile. In addition, some drug infusion systems are implantable to more effectively and less obtrusively dispense such fluid medication to a patient.  
           [0003]    Implantable devices and techniques for treating a patient by drug infusion are well known in the prior art. For instance, U.S. Pat. No. 5,782,798, Rise, entitled Techniques For Treating Eating Disorders By Brain Stimulation and Drug Infusion; and U.S. Pat. No. 5,814,014, Elsberry et al, Techniques of Treating Neurodegnerative Disorders by Brain Infusion, each assigned to Medtronic, Inc., Minneapolis, Minn., disclose such devices and techniques and are hereby incorporated by reference.  
           [0004]    Another example of a drug infusion device is shown in U.S. Pat. No. 3,527,220, Summers, entitled Implantable Drug Administrator, an implantable drug administrator having a refillable bladder which can be filled with a drug and a pump for selectively pumping the drug from the bladder into any desired area of the body. The administrator includes an indicator for indicating when the desired amount of the drug has been injected.  
           [0005]    In U.S. Pat. No. 3,951,147, Tucker et al, entitled Implantable Infusate Pump, a rechargeable infusate pump for implantation in the human body can be refilled periodically by injection through an inlet septum under the skin. A conduit conducts fluid to an infusion site in the body. The pump outlet includes a special controller flow controller which is able to very accurately meter the infusate to the selected body site.  
           [0006]    A problem with these implantable drug infusion devices is that there is no way to provide a simple external means to select the dosage amounts and intervals from a wide range of possible doses and intervals, and verify that a desired change had been made.  
           [0007]    U.S. Pat. No. 4,146,029, Ellinwood, Self-Powered Implanted Programmable Medication System and Method, discloses a device and method for dispensing medication internally of the body utilizing an implanted system which includes medication storage and dispensing control circuitry having control components which may be modified by means external of the body being treated to control the manner of dispensing the medication within such body. In particular, extracorporeal control means may provide some measure to achieve selected medication programs corresponding to particular codes.  
           [0008]    U.S. Pat. No. 4,692,147, Duggan, Drug Administration Device, assigned to Medtronic, Inc., Minneapolis, Minn., discloses an implantable drug administration device which can be non-invasively programmed to change both the dosage amount and the dosage interval. Verification of the received dosage and interval commands is achieved by means of an audio transducer which is attached to the device case.  
           [0009]    The implantable drug administration device described in Duggan allows a medical professional to program to the delivery rate of a drug contained in the reservoir of the device over a specified interval.  
           [0010]    Not infrequently, a medical professional prescribes more than one drug to be used in an implantable drug infusion device. More than one active ingredient present in the reservoir of the implantable infusion device increases programming difficulties substantially. Not only must the medical professional program the drug infusion device to perform a series programmed steps in order to deliver one drug to the patient, the medical professional must take into account the affect of creating or modifying a program for one of the drugs on the delivery of all other drugs also contained within the same reservoir of the drug infusion device. If the medical professional changes the delivery rate of the drug infusion device to increase the dose of one drug to be delivered to the patient in a period, that change will also increase the dose of all other drugs that are also contained in the same reservoir. With a complex dosing regimen and a plurality of active drugs, the danger for confusion and error is significant.  
         BRIEF SUMMARY OF THE INVENTION  
         [0011]    In one embodiment, the present invention provides a drug infusion system is capable of delivering a fluid medication to a patient under direction of a medical professional. The fluid medication consists of a plurality of drugs including a primary drug and a secondary drug. A drug delivery module is capable of delivering the fluid medication to the patient from a reservoir at a flow rate. A controller allows the medical professional to specify a dose of the primary drug per unit time for the patient. A flow rate is determined as a function of the dose of the primary drug and the concentration of the primary drug. A dose of the secondary drug per unit time for the patient is determined as a function of the flow rate and the concentration of the secondary drug. The controller communicates the dose for the secondary drug per unit time to the medical professional.  
           [0012]    In a preferred embodiment, the concentration of each of the plurality of drugs is stored in the drug delivery module.  
           [0013]    In a preferred embodiment, the controller communicates the dose for the secondary drug per unit time to the medical professional via a display.  
           [0014]    In another embodiment, the present invention provides a drug infusion system capable of delivering a fluid medication to a patient under direction of a medical professional. The fluid medication consists of a plurality of drugs. A drug delivery module is capable of delivering the fluid medication to the patient from a reservoir. A controller allows the medical professional to specify a first parameter of delivery of one of the plurality of drugs. A first parameter of another of the plurality of drugs is determined as a function of the first parameter of delivery of the one of the plurality of drugs and a second parameter of another of the plurality of drugs. The controller communicates the first parameter of another of the plurality of drugs to the medical professional.  
           [0015]    In a preferred embodiment, the drug infusion system further determines the flow rate as a function of the first parameter of the one of the plurality of drugs and a second parameter of the one of the plurality of drugs.  
           [0016]    In a preferred embodiment, the first parameter of another of the plurality of drugs is determined as a function of the flow rate and the second parameter of another of the plurality of drugs.  
           [0017]    In a preferred embodiment, the second parameter of each of the plurality of drugs is stored in the drug delivery module.  
           [0018]    In a preferred embodiment, the drug delivery module is implantable.  
           [0019]    In a preferred embodiment, the drug infusion system further determines an amount of the fluid medication contained in the reservoir.  
           [0020]    In a preferred embodiment, the controller communicates the first parameter of another of the plurality of drugs to the medical professional via a display.  
           [0021]    In another embodiment, the present invention provides a dosing tool, useable by a medical professional, for an implantable drug infusion system capable of delivering a fluid medication to a patient from a reservoir at a flow rate. The fluid medication consists of a plurality of drugs including a primary drug and a secondary drug. A controller allows the medical professional to specify a dose of the primary drug per unit time for the patient. The flow rate is determined as a function of the dose of the primary drug and the concentration of the primary drug. A dose of the secondary drug per unit time for the patient is determined as a function of the flow rate and the concentration of the secondary drug. The controller communicates the dose for the secondary drug per unit time to the medical professional.  
           [0022]    In a preferred embodiment, the dosing tool further determines an amount of the fluid medication contained in the reservoir.  
           [0023]    In a preferred embodiment, the controller communicates the dose for the secondary drug per unit time to the medical professional via a display.  
           [0024]    In another embodiment, the present invention provides a method of communicating dosing information for an implantable drug infusion system to by medical professional when the drug infusion system is being programmed by the medical professional. The drug infusion system is capable of delivering a fluid medication to a patient from a reservoir at a flow rate. The fluid medication consists of a plurality of drugs including a primary drug and a secondary drug. The method allows the medical professional to specify a dose of the primary drug per unit time for the patient. The method determines the flow rate as a function of the dose of the primary drug and the concentration of the primary drug. The method determines a dose of the secondary drug per unit time for the patient as a function of the flow rate and the concentration of the secondary drug. The method communicates the dose for the secondary drug per unit time to the medical professional.  
           [0025]    In a preferred embodiment, the method further determines an amount of the fluid medication contained in the reservoir.  
           [0026]    In a preferred embodiment, the communication step is accomplished via a display.  
           [0027]    In another embodiment, the present invention provides a drug infusion system capable of delivering a fluid medication to a patient under direction of a medical professional. An implantable drug delivery module, having operating parameters, is capable of delivering the fluid medication to the patient. A memory, contained in the implantable drug delivery module, stores a plurality of sets of the operating parameters, one of the plurality of sets of the operating parameters being active. A controller allows the medical professional to specify the operating parameters by modifying the parameters stored in one of the plurality of sets of the operating parameters which is not active. The controller also allows the medical professional to alter which of the plurality of sets of operating parameters is active.  
           [0028]    In another embodiment, the present invention provides a method of controlling a drug infusion system capable of delivering a fluid medication to a patient under direction of a medical professional. An implantable drug delivery module is capable of delivering the fluid medication to the patient, the implantable drug delivery module having operating parameters. Memory, contained in the implantable drug delivery module, stores a plurality of sets of the operating parameters, one of the plurality of sets of the operating parameters being active. The method stores a set of operating parameters in the memory in one of the plurality of sets which is not active. The method determines that the set of operating parameters is valid. The method switches which of the plurality of sets which is active to the one of the plurality of sets of operating parameters in which the set of operating parameters were stored in the storing step. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]    [0029]FIG. 1 is a schematic view of a patient with a drug infusion device implanted within the patient&#39;s body.  
         [0030]    [0030]FIG. 2 is a block diagram of a drug infusion device of the present invention;  
         [0031]    [0031]FIG. 3 is a block diagram illustrating the random access memory and register layout of a portion of drug infusion device of the present invention;  
         [0032]    [0032]FIG. 4 is an illustration of a drug entry display provided to a programmer of the drug infusion system of the present invention;  
         [0033]    [0033]FIG. 5 is another illustration of a drug entry display provided to a programmer of the drug infusion system of the present invention;  
         [0034]    [0034]FIG. 6 is an illustration of a drug delivery display provided to a programmer of the drug infusion system of the present invention showing simple continuous mode programming;  
         [0035]    [0035]FIG. 7 is another illustration of a drug delivery display provided to a programmer of the drug infusion system of the present invention showing simple continuous mode programming; and  
         [0036]    [0036]FIG. 8 is an illustration of a drug delivery display provided to a programmer of the drug infusion system of the present invention showing flex mode programming. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0037]    [0037]FIG. 1 is a schematic view of a drug infusion system  12  of the present invention. Implantable drug infusion device  14  is shown implanted within the body of patient  10 . Drug infusion device  14  is programmable through a telemetry link from programmer  20 , which is coupled via a conductor  22  to a radio frequency antenna  24 . Methods of communicating, using radio frequency telemetry, with implanted treatment devices in order to program such implanted drug infusion devices, are well known in the art.  
         [0038]    [0038]FIG. 2 is a block diagram of the drug infusion system  12  having an implantable drug infusion device  14 . Drug infusion device  14  consists of an internal memory unit  26  containing memory and registers and circuitry which provides internal drug delivery instructions to drug delivery module  30 . External programmer  20  acts as an input-output device for drug infusion system and also provides computational support for memory unit  26 . Memory unit  26  and programmer  20 , operating together, function as a controller  32  controlling drug delivery module  30  in the delivery of fluid medication to patient  10 . Drug delivery module  30  has a reservoir  34  for holding the fluid medication to be infused and pump  36  coupled to patient  10  through catheter tubing  38 . Such drug delivery modules  30  are well known in the art.  
         [0039]    Memory unit  26  receives programming information, via telemetry, from programmer  20  through conventional means. Programming information, once stored in memory unit  26 , provides the dosing regimen to be performed by drug delivery module  30 .  
         [0040]    Memory unit  26  stores information concerning aspects of the operation of drug infusion device  14 . Memory unit  26  may, for example, store information about patient  10  including name, address and contact information. In addition, memory unit  26  may store information about the drug delivery module  30  including pump  36  and catheter  38 . Among the settings that may be stored are the model number and serial number of pump  36 , the volume of reservoir  34 , battery condition and information about catheter  38 , including the length of all sections of catheter  38 . Information about the calibration of pump  36  may also be stored. During the pumping operation, controller  32  (preferably through programmer  20 ) also calculates, or otherwise determines, the volume of fluid medication remaining in reservoir  34 .  
         [0041]    In order to perform its function, memory unit  26  also stores information about each drug contained in reservoir  34 , including the drug name, or other identifier, and the concentration of the drug in the overall volume of fluid medication contained in reservoir  34 . Typically, this data is entered at the time that drug infusion device  14  is loaded with fluid medication.  
         [0042]    Throughout this description, while it is contemplated that any or all of the calculations performed by controller  32  could be performed in either programmer  20  or memory unit  26 , it is recognized that drug delivery device  14 , being an implantable device, will have a limited amount of processing power and energy source. Therefore, it is preferred that the calculations referred to as being performed by controller  32  (encompassing both programmer  20  and memory unit  26 ) actually be performed by programmer  20 , in order to control the precious resources of implantable drug infusion device  14 . At the same time, it is preferred that information concerning implantable drug infusion device  14 , patient  10 , all drug contained in reservoir  34  and the drug regimens implemented, all be stored in memory unit  26  so as to be available no matter which of a plurality of programmers  20  may be operationally coupled with implantable drug infusion device  14  to form drug infusion system  12 .  
         [0043]    Alternatively, the amount of drug, e.g., in micrograms, can be entered into controller  34  when drug infusion device is loaded with fluid medication. That information, along with the also known volume of fluid medication, e.g., 12 milliliters, allows controller  34  to calculate the concentration of the drug. In the example given above, if the volume of fluid medication is 12 milliliters and the amount of drug is 20 micrograms, then the concentration the drug 1.666 micrograms per milliliter (20 micrograms divided by 12 milliliters).  
         [0044]    Drug infusion device  14  may also contain (and be programmed for) more than one drug. Typically, a multiple drug prescription, the drug cocktail containing multiple drugs, or an active drug and a neutral agent such as saline, is premixed and then injected into the implanted drug infusion device. The concentration of each of the drugs contained in the drug cocktail is known, or the amount of each of the drugs contained in the drug cocktail is known, or a combination of the above. The requisite information for each of the drugs contained in the drug cocktail are entered into memory unit  26  in the same way as described above with respect to one drug.  
         [0045]    In a preferred embodiment, the patient information, pump information and the drug information is all stored in memory unit  26  located in an implanted drug infusion device  14 . While all of this information readily available from within implanted drug infusion device  14 , a medical professional may use any applicable programmer  20 , at any time and any location, to read information from implanted drug infusion device  14  and to program drug infusion device  14 .  
         [0046]    [0046]FIG. 3 illustrates a preferred manner of storing such information within memory unit  26  of drug infusion device  14 . Registers  40  contain information concerning programmed drug regimens, including the number of steps, their frequency (if repetitive), duration and pumping rate. Such information is generic to all drugs contained in reservoir  34  irrespective of the nature of the drug or drugs contained in reservoir  34  or the number of drugs contained in reservoir  34 . In general, the information contained in registers  40  represents the information which applies whichever drug is contained in reservoir  34  or applies equally to all drugs in reservoir  34 . For example, the delivery rate represents the programmed rate at which pump  36  delivers fluid medication to patient  10 . Since all of the drugs present in reservoir  34  of drug infusion device  14  are delivered to patient from common reservoir  34  at whatever rate pump  36  is programmed, all drugs are delivered to patient  10  at precisely the same rate. Hence, information about delivery rate, pumping rate, may be stored in registers  40  and can be common to all drugs contained in drug infusion device  14 .  
         [0047]    Drug RAM (random access memory)  42  holds information about each of the drugs which are contained in reservoir  34  of drug infusion device  14 . As noted above, such drug information includes the name, or other identifier, of each individual drug as well as the concentration of the drug in total fluid volume of fluid medication and/or the amount of such drug contained in reservoir  34 .  
         [0048]    In a preferred embodiment, drug RAM  42  is separated into two at least two parts, labeled part A and part B. Parts A and B of drug RAM  42  are identical and each contains exactly the same type of information, although, of course, the data contained in each individual memory location or locations may differ. Thus, parts A and B of drug RAM  42  are completely redundant. However, only either part A or part B of drug RAM  42  is active at any one time.  
         [0049]    The information in part A when active, for example, of drug RAM  42 , in conjunction with the information contained in registers  40 , specifies the operating parameters and controls the operation of drug delivery module  30  and, therefore, delivers the proper amount of fluid medication to patient  10  at the proper time. In this case, the operating parameters in part B of drug RAM  42  are inactive and do not control the operation of drug infusion device  14 . Conversely, when the operating parameters stored in part B of drug RAM  42  are active, the information contained therein, along with the information contained in registers  40 , controls the operation of drug infusion device  14  and the operating parameters stored in part A of drug RAM  42  are inactive and do not control any aspect of the operation of drug infusion device  14 . Thus, parts A and B are completely redundant and alternatively control the operation of drug infusion device  14 .  
         [0050]    When new information about the drugs contained in reservoir  34  of drug infusion device  14 , patient information or information about pump  36  and/or catheter  38  is written to drug RAM  42 , it is written to the part of drug RAM  42  which is not, at that time, active.  
         [0051]    Mainly due to the amount of information which may need to be written to the inactive portion of drug RAM  42 , e.g., information about multiple drugs including their name and concentration, the writing of such information may need to be performed in separate write steps or, in other words, in separate packets of information. Because the information is not written in a simple step, or in a single packet, there exists the possibility that the writing process may be interrupted. This could occur, for example, if communication with implantable drug infusion device  14  was lost due to movement of patient  10  or of programmer  20  or could occur if battery power were lost to programmer  20 .  
         [0052]    Since the information about drugs, patient and pump  36  and/or catheter  38  are written to the portion of drug RAM  42  which is not currently active, the inactive portion of drug RAM  42  serves as a shadow RAM to hold such information until the entire writing process can be finished. Registers  40  can then be updated to transfer control of drug infusion device  12  from the previously active portion of drug RAM  42  to the newly written and previously inactive portion of drug RAM  42 .  
         [0053]    Information about the rate, duration and frequency of each step of drug delivery programmed into drug infusion device  12  is contained in registers  40 . The rate, duration and frequency information contained in registers  40 , along with the information contained in drug RAM  42  and information contained in registers  40  on which portion of drug RAM  42  is active, determine the operation of drug infusion device  12 . In a preferred embodiment, new information written into registers  40  concerning rate, duration, frequency and which portion of drug RAM  42  is active, is written as a single step. In other words, this information is written as a single packet of data. Thus, there is no possibility that some of the information will be written and the writing process will be interrupted. Thus, new information, if needed, is written into the inactive portion of drug RAM  42  first and then new information, if needed, is written into registers  40  and control is transferred from the previously active portion of drug RAM  42  to the previously inactive portion of drug RAM  42 . This stepped process enables information from a plurality of writing steps to be transferred to the memory which controls drug infusion device  12  without the danger that an interruption in writing process will result in only a portion of the intended new information controlling drug infusion device  12 .  
         [0054]    It is also to be recognized and understood that while registers  40  and drug RAM  42  of memory unit  26  have been described, in a preferred embodiment, as having two parts, namely parts A and B, that the same principles apply and registers  40  and drug RAM  42 , or either of them, may be separated into more than two parts with equally advantageous operating results.  
         [0055]    The operating parameters stored in each part (part A and part B) of drug RAM  42  of memory unit  26  may be again divided into separate areas. Each part of drug RAM  42  contains information relating to each of the drugs contained in reservoir  34 . For example, if two drugs are contained in reservoir  34  (and part A is active), then part A of drug RAM  42  will be divided into sections. There is a section devoted to information about drug one and a section devoted to information about drug two. And, of course, drug RAM  42  may be separated into any multiple of parts, at least one for each of the number of drugs which are contained, or which may be contained, in reservoir  34 .  
         [0056]    If more than one drug is prescribed for drug infusion system  12 , the proper amount of each drug will typically be pre-mixed before insertion into reservoir  34  of implantable drug infusion device  14 . Each drug in the mixture will have a concentration, i.e., an amount of each drug compared to the overall volume of fluid medication contained, to be contained, in reservoir  34 . At or near the time that the drug mixture containing the multiple drugs is inserted into reservoir  34 , usually through a syringe for an implantable drug infusion device  14 , data concerning all of the drugs contained in fluid medication is entered into memory unit  26 .  
         [0057]    Generally, one of the drugs contained in fluid medication is the primary drug. The primary drug is main drug around which the prescription drug mix, or drug cocktail, is based. It is the primary drug on which the basic programming decisions for drug infusion system  12  are based.  
         [0058]    While one drug may be the primary drug contained in the fluid medication, the medical professional must not overlook the effects of other drugs contained in the fluid medication. If the prescription for the amount of the primary drug in increased, typically by increasing the delivery rate of pump  36 , the amount of all other drugs, which are contained in fluid medication, delivered to patient  10  will also be increased. Thus, the medical professional must take into account all of the drugs contained in fluid medication. If the dose for the primary drug is changed, then the dose for all of the drugs will be changed. If the medical professional does not keep track of the affect of modifying the delivery rate on all of the drugs contained in the fluid medication, the patient  10  may receive more or less of the other drugs contained in the fluid medication.  
         [0059]    Programmer  20  portion of controller  32  provides an interface between the medical professional and the potentially implanted drug infusion device  14 . In particular, programmer  20  provides a medium for data entry into memory  26  of drug infusion device  14  and provides a display for communication of information contained in memory  26  to the medical professional. As noted above, programmer  20  also, preferably, provides computational power to perform the calculations associated with drug infusion system  12 .  
         [0060]    [0060]FIG. 4 illustrates an “input-output” display  50  on programmer  20  with the drug tab  52  selected. Display  50 , associated with drug tab  52 , provides a mechanism for the medical professional to input information about the drugs contained in the fluid medication to controller  32 . Display  50  also provides a mechanism for the medical professional to learn with what drugs controller  32  has been programmed.  
         [0061]    Drug entry display has an entry ( 54 ,  56 ) for each of the multiple drugs contained fluid medication. Entry number 1 ( 54 ) contains information on the primary drug including the name of the drug and the concentration of the drug. In the embodiment illustrated in FIG. 4, entry  54  contains Baclofen. Entry  54  also contains information about the concentration of the primary drug Baclofen, here listed as 20.0 micrograms. This concentration means the fluid medication has 20.0 micrograms of Baclofen per milliliter of fluid medication. Entry  56  illustrates the entry of information about drug 2, a secondary drug in fluid medication. In the embodiment illustrated in FIG. 4, entry  56  contains morphine. The information about secondary drug morphine is expanded from its read-only status at entry  56  to data entry dialog boxes  58 ,  60  &amp;  62 . Dialog box  58  appears to facilitate entry of the actual name of morphine as a secondary drug. This is the spot that the medical professional enters this information. Similarly, dialog box  60  facilitates entry of amount of the concentration of morphine and dialog box  62  facilitates entry of the units associated with the amount of the concentration of morphine. In the example illustrated in FIG. 4, secondary drug morphine has a concentration of 40.0 milligrams per milliliter of fluid medication. Once the medical professional is assured that the information contained in dialog boxes  58 ,  60  &amp;  62  are correct, the “OK” box can be clicked the entry  56  will be updated with the proper information from dialog boxes  58 ,  60  &amp;  62 .  
         [0062]    [0062]FIG. 5 illustrates the appearance of drug entry display  50  with dialog box  58 ,  60  &amp;  62  closed. Entries  54  and  56  appear as they did in FIG. 4. In addition, drug entry display  50  illustrated in FIG. 5 contains spaces for entries  64 ,  66  &amp;  68 . Since, only two drugs are contained in fluid medication in the example illustrated in FIG. 5, entries  64 ,  66  &amp;  68  are empty. If, however, fluid medication contained more than two drugs, information about the additional drugs would be contained in entries  64  (if there were a total of three drugs),  64  and  66  (if there were a total of four drugs) and entries  64 ,  66  and  68  (if there were total of five drugs). Of course, additional drugs could be accommodated with additional entries.  
         [0063]    In addition to information about each individual drug contained in fluid medication, display  50  also contains information (entry  70 ) about the estimated volume of fluid medication contained in reservoir  34 . The initial value entered into entry  70  would be the total amount of fluid medication which is, or is to be, inserted into reservoir  34  of drug infusion device  14 . After initial entry of the value contained in entry  70 , drug infusion device  14  calculates the amount fluid medication which has been delivered by drug infusion device  14  and subtracts that amount from the initial value entered into entry  70 . Drug infusion device, via controller  34 , then causes the updated amount of fluid medication remaining in reservoir  34  (as calculated above) to be displayed in entry  70 .  
         [0064]    [0064]FIG. 6 illustrates drug delivery display  72  as selected by drug delivery tab  74 . Drug delivery display  72  has been selected, via delivery mode drop-down box  80 , to be in “simple continuous” mode, meaning that pump  36  is programmed to delivery fluid medication at a constant rate. Drug delivery display  72  has entry  76  which is indicative of the prescribed dose of the primary drug (entered in drug entry display screen  50 ). In this part of the example, the primary drug is identified in entry  76  as Baclofen. The data entry in the lower portion of drug delivery display  72  is open and illustrates the entering of a daily dose of Baclofen (drug 1, the primary drug) of 200 micrograms.  
         [0065]    The daily dose of the primary drug entered in drug delivery display  72  converted by controller  32 , preferably programmer  20 , into a drug delivery rate, i.e., the rate at which pump  36  delivers the fluid medication to patient  10 , and is transferred to memory unit  26 . Controller  32  calculates the rate at which pump  36  delivers fluid medication to patient  10  by converting, if necessary, the daily dose the primary drug into a dose of the primary drug in a smaller unit of time. This amount of dose is then divided by the concentration of the primary drug in the fluid medication contained in reservoir  34  resulting in an amount of the fluid medication to be delivered to patient  10  over that unit of time. Pump  36  is then set to deliver the fluid medication at that rate.  
         [0066]    [0066]FIG. 7 illustrates drug delivery display  72  also as selected by drug delivery tab  74  and also in simple continuous mode as selected by delivery mode drop-down box  80 . Drug delivery display  72  illustrated in FIG. 7 differs from drug delivery display  72  illustrated in FIG. 6 in that the data entry in the lower portion of drug delivery display  72  is now closed, the data for the drug delivery rate for primary drug Baclofen having been entered in entry  76 . Closing of the data entry portion allows drug delivery display  72  not only entry  76  for primary drug Baclofen but also allows display entry  78  for secondary drug identified as morphine in this portion of the example.  
         [0067]    Drug dose entry  76  displays the secondary drug name, morphine, and the daily dose for the secondary drug, here 5,000 milligrams. In contrast to drug dose entry  76  for primary drug Baclofen, drug dose delivery entry  78  for secondary drug morphine is not directly entered by the medical professional. Since the medical professional has already set the rate at which pump  36  delivers fluid medication to patient  10  via drug dose delivery rate  76 , all other drugs in fluid medication will be delivered at that same rate. Hence, drug dose entry  78  is instead an informational display of a calculated daily dose for secondary drug morphine for the medical professional.  
         [0068]    The daily dose of secondary drug, morphine, displayed here in entry  78  is calculated by controller  32 . The rate at which pump  36  is set to deliver the fluid medication to patient  10  is known by the calculation resulting from the dosing programmed for the primary drug, Baclofen. The rate at which pump  36  is set to deliver fluid medication to patient  10  per unit time is multiplied by the concentration of the secondary drug in the fluid medication contained in reservoir  34 . This results in the dose of the secondary drug set to be delivered to patient  10  per unit of time. The dose is then converted into a daily dose simply by adjusting the time scale, if necessary. The resulting daily dose is then displayed in entry  78  of drug dose display  72 .  
         [0069]    While FIGS. 6 and 7 have been illustrated with two drugs, a primary drug and a secondary drug, it is to be recognized and understood that more secondary drugs could also be mixed in fluid medication and, hence, also be added as additional entries in drug delivery display  72 . A drug contained in fluid medication will have an entry in both drug entry display  50  and drug delivery display  72 .  
         [0070]    [0070]FIG. 8 illustrates drug delivery display  72 , as selected by drug delivery tab  74 , this time illustrating the programming of the delivery of primary drug Baclofen in “flex mode” as selected by drop-down box  80 . In flexible mode, the delivery rate for the primary drug can be varied based on multiple time periods, such as particular hours, in a longer time period, such as a day. The variation in drug delivery rate can be entered directly by particular interval step as shown at  82  or can be displayed and/or entered as illustrated in the alternative graphical representation  84 .  
         [0071]    Again, once the delivery mode and rate for the primary drug has been entered, controller  32  of drug infusion device  14  calculates and displays, via drug delivery display  72 , the daily dose and drug delivery particulars, if in flexible mode, of a secondary drug or drugs.  
         [0072]    By displaying the daily dosage or particular delivery rates for a secondary drug or drugs directly in the display of programmer  20 , the medical professional is kept apprised of the affect of dosing decisions based upon the primary drug on dosing for a secondary drug or drugs. The makes programming drug infusion device easier, more straightforward and helps eliminate errors and dosing miscalculations.  
         [0073]    Thus, embodiments of the drug infusion device with multiple medications are disclosed. One skilled in the art will appreciate that the present invention can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation, and the present invention is limited only by the claims that follow.