the present invention is embodied in apparatus and related methods for automatically implementing intermittent intravenous medical therapy using a fluid bag having a configuration that largely defines the sequence and flow rate of the infusion of medications into a patient . the invention is advantageous in simplifying the administration of intermittent intravenous medical infusion therapy . a patient ( or caregiver ), with relatively little medical training , would receive a fluid bag having chambers configured with predetermined geometries and prefilled with prescribed medications and would self - administer the therapy using an infusion pump . because the therapy is defined by the bag &# 39 ; s configuration , the patient , nurse or caregiver would not need to program the infusion pump or perform manual manipulations during the infusion procedure thus substantially reducing the patient &# 39 ; s risks due to improper administration . referring to fig1 and 2 , the invention is embodied in a multiple chamber fluid bag 20 or cartridge having a plurality of fluid chambers 22 , 24 , 26 and 28 . the bag is a laminate of two flexible plastic sheets attached together to form four separate and distinct chambers and corresponding passageways ( not shown ) from each chamber to a common passageway 30 and an exit port 31 . the unitary bag is relatively flat with the chambers generally lying in a common plane . when chambers are filled with fluid , they expand to have a cylindrical or a &# 34 ; pillow - like &# 34 ; shape . an infusion tube 32 is coupled to the exit port . a connector 34 is coupled to the tube for connection to standard i . v . couplers . a clip 36 is provided on the tube to stop fluid flow through the tube if needed . although four chambers are shown in fig1 ., as will be discussed in more detail below , the fluid bag may be configured with any of a wide variety of chamber numbers , positions , sequences , and geometries . each chamber may also include one or more fill ports 38 for filling the chambers . the bag may also include alignment holes 40 ( or other alignment vehicles ) for positioning the bag within an infusion pump having corresponding alignment pegs ( not shown ). the chambers 22 , 24 , 26 and 28 may be emptied by applying pressure to the bag 20 . as discussed below with respect to fig2 and 25 , the pressure may be applied by a roller traveling from the top of the bag toward its bottom at a steady rate . other apparatus and methods for applying pressure to the chambers are also discussed in more detail below with respect to fig1 - 23 . the chambers of the fluid bag 20 of fig1 and 2 are suitably configured to implement a sash infusion therapy . sash is an acronym for saline - antibiotic - saline - heparin . the first chamber 22 is typically filled with about 5 ml . of saline solution . the second chamber 24 is typically filled with about 100 ml . of liquid antibiotic . the third and fourth chambers are each typically filled with about 5 ml . of saline solution and heparinized solution , respectively . with reference now to fig3 the bag 20 can be constructed from two flexible sheets of plastic film 44 by welding the sheets together along weld lines 46 . the welds may be ultrasonic or heat welds or the like . the weld lines define each chamber &# 39 ; s geometry and size thus its volume . the geometry and volume of each chamber defines the sequence and rate at which the corresponding prescribed medication is infused into the patient . the four alignment holes 40 may be cut before or after the sheets are welded . the plastic film may be formed of any medically acceptable plastic , e . g ., polyvinyl chloride ( pvc ), polyolefin or other suitable material . the rate at which the medications exit the chambers may be additionally defined by restrictive openings at the exit of each chamber , e . g ., by a restrictive orifice in the common passageway 30 , by a valve in the infusion tube 32 , or the like . exit port openings for controlling the flow rate from the chambers are discussed below in more detail with respect to fig9 . fig4 shows a top view of a cartridge 310 of the present invention . the cartridge 310 has four chambers 312 , 314 , 316 and 318 for holding the sash fluids . the first chamber 312 holds 3 - 10 cc &# 39 ; s of saline solution . the second chamber 314 holds 10 - 250 cc &# 39 ; s of the desired medicine . the third chamber 316 holds 3 - 10 cc &# 39 ; s of saline and the forth chamber 318 holds 3 - 10 cc &# 39 ; s of heparin . the first chamber 312 is filled via port 332 ; the second chamber 314 is filled via port 334 ; the third chamber 316 is filled via port 336 and the fourth chamber 318 is filled via port 338 . ports 332 , 334 , 336 , and 338 are standard injection ports or luer lock connections . chambers 312 , 314 , 316 and 318 are supplied factory pre - filled or are pre - filled by a pharmacist with the correct fluids . after the ports are filled by the pharmacist they are sealed by the self sealing injection port or by a cap on the luer lock connection . if the chamber is factory pre - filled , it may be heat sealed after filling which would eliminate the need for an inlet port . at the exit port of each chamber is a check valve that only permits fluid flow in one direction . check valves 322 , 324 , 326 and 328 are at the exit ports of chambers 312 , 314 , 316 and 318 , respectively . each check valve permits fluid flow into line 330 as shown in fig4 . line 330 passes through clamp 340 that is used to completely restrict any fluid flow . line 330 terminates at luer connection 342 that is used to connect to the patient catheter . the cartridge 310 is constructed as a two piece laminate made from pvc , polyolefin or similar materials typically used for iv bags . the laminate is heat sealed or adhesively bonded . the cross - hatched areas 320 show the sections of the cartridge 310 that have been bonded together . the unbonded areas are represented by the chambers 312 , 314 , 316 and 318 . the chambers can be made in many different geometric shapes . these shapes can be used to control the flow rate of the medication in the chambers . this will be discussed with reference to fig9 and 10 . when the chambers have been filled with the desired fluids , the cartridge 310 is placed in the pump unit , not shown in fig4 for infusion of the medication . rollers will squeeze the fluids in sequence from chambers 312 , 314 , 316 and 318 into the line 330 , past the clamp 340 to luer connection 342 and into the patient catheter . when the infusion sequence is completed , the cartridge can be disconnected from the catheter and pump and then discarded . this infusion process does not involve the use of needles or syringes and therefor increases the safety factor for anyone administering the procedure . the fluid dynamics of the dispensing process will now be discussed with reference to fig5 - 10 . fig5 , 7 and 8 show alternate geometric shapes for the fluid chambers discussed with reference to fig4 . fig5 shows a fluid chamber 350 having a filling port 356 and an exit port 352 . as fluid chamber 350 is compressed by the pumping device , to be discussed later , the fluid is expelled from the chamber 350 through the exit port 352 . the shape of chamber 350 can provide a higher fluid flow rate in the beginning and a steadily decreasing flow rate until all the fluid has been dispensed . the fluid flow rate will be discussed in greater detail with reference to fig9 and 10 . fig6 shows fluid chamber 354 , filling port 358 and exit port 355 . the shape of this fluid chamber can provide a constant fluid flow rate from the beginning to the end of the infusion . fig7 shows fluid chamber 360 with filling port 64 and exit port 362 . the shape shown in fig7 can provide a nonlinear decrease in the flow rate from the beginning to the end of the infusion . fig8 shows fluid chamber 366 having filling port 368 and exit port 365 . the shape shown in fig8 can provide an initially constant fluid flow rate followed by a steadily decreasing flow rate during the last part of the infusion . the factors involved in determining the fluid flow rate will now be discussed with reference to fig9 and 10 . fig9 shows a fluid chamber 370 having an exit port 372 . the exit port 372 has a length represented by l and a radius represented by r . p 1 represents the pressure inside the fluid chamber 370 and p 2 represents the pressure outside the fluid chamber 370 . in the following formula q represents the mass flow rate in ml / min and u represents the viscosity of the fluid in the fluid chamber 370 . the formula is as follows : the above equation is poiseville &# 39 ; s law for homogeneous fluid . p 1 - p 2 is the difference in pressure between the inside and the outside of the fluid chamber 370 . a change in the radius r of the exit port 372 or a change in the length l of the exit port 372 can have a large effect on the flow rate q . the elasticity of the materials used to construct the fluid chamber can also have an effect on the flow rate . however , for the purpose of this discussion it is assumed that the elasticity will not have a significant effect on the flow rate . fig1 shows a fluid chamber 380 having an exit port 386 . if it is assumed that the r and l are constant , then the major factor in determining the flow rate will be p 1 . if a press type roller moving at a constant rate starts to compress the fluid chamber 380 at point 388 then the pressure p 1 will continually increase . thus the pressure generated at line 384 will be much greater than the pressure generated at line 382 , causing a much higher flow rate at line 384 . fig1 shows a fluid chamber that can have an increasing flow rate from the beginning to the end of the infusion . differing infusion therapies for a wide variety drug regimens may be implemented by the chamber configurations as shown , for example , in fig1 a - 11f . for example , as shown , in fig1 a the infusion bag 20 is configured with four separate fluid chambers 22 , 24 , 26 and 28 suitable for implementing a sash drug regimen . the intravenous antibiotic is contained in the second chamber 24 . the volume and shape of the second chamber may be prescribed to affect the volume and the administration rate of the antibiotic as shown in fig1 a - 11c . in fig1 a , the antibiotic chamber 24 has a square shape and a volume of about 100 ml . in fig1 b , the antibiotic chamber 24 has an elongated rectangular shape and a volume of about 50 ml . the antibiotic chamber 24 shown in fig1 c , also has a volume of 50 ml , but has a wide shortened rectangular shape . accordingly , using a constant speed roller that compresses the chambers from top to bottom , the drug prescribed by the bag in fig1 b is infused at a slower rate than the drug prescribed by the bag in fig1 c . the chamber , of course , is not required to have a rectangular shape and , thus , it may have any shape ( e . g ., circular , triangular , diamond , etc .) which is beneficial for administering a prescribed infusion therapy . further , drugs that are incompatible for premixing may be stored in separate chambers until they are simultaneously infused into the patient . as shown in fig1 d , simultaneous infusion of separate drugs may be readily accomplished by configuring the bag 48 to have two side - by - side chambers 50 and 52 . the first chamber 50 is filled with a first drug and the second chamber 52 is filled with a second drug . accordingly , as the roller travels down the bag , it simultaneously compresses the two side - by - side drug chambers so that the two drugs are simultaneously infused into the patient , thus simplifying the infusion of the two incompatible drugs without premixing . as shown in fig1 e , the infusion therapies that may be addressed by configuring the bag &# 39 ; s geometry are not limited to the sash procedure . the bag in fig1 e is configured with six separate chambers . the first , third and fifth chambers 56 , 58 and 60 can be filled with a saline solution and the sixth chamber 62 can be filled with heparin . the second and fourth chambers 64 and 66 , however , can be filled with first and second drugs , respectively . of course , this bag may be used to administer intermittent infusions of a single drug by filling the second and fourth chambers with the same drug . similarly , as shown in fig1 f , multiple doses of a drug may be intermittently administered at prescribed time intervals by a bag 70 having its chambers configured in accordance with the dosage regimen . thus , the first chamber 72 can be filled with a first prescribed drug dosage , the second chamber 74 can be filled with a saline solution , the third chamber 76 can be filled with a second prescribed drug dosage , the fourth chamber 78 can be filled with a saline solution , the fifth chamber 80 can be filled with a third described drug dosage , and finally , the sixth chamber 82 can be filled with a final saline solution . fig1 shows a cartridge 440 having six fluid chambers 454 , 456 , 458 , 460 , 462 and 464 . each fluid chamber has its respective check valve 468 , 470 , 472 , 474 , 476 and 478 in its respective exit port . each of the fluid chambers 454 , 456 , 458 , 460 , 462 and 464 is filled via its respective filling port 442 , 444 , 446 , 450 , 448 and 452 as previously described . the exit port for each fluid chamber empties into line 466 causing the fluid in the chambers to pass along line 466 through clamp 480 to luer connector 482 . the connector 482 can be any type of connector required for the environment in which the cartridge 440 is used . fluid chamber 454 could be used to deliver saline as previously discussed . chambers 456 , 458 , 460 and 462 would be used to deliver medications concurrently to the patient . for instance , fluid chambers 456 and 458 will deliver the medications concurrently with both chambers starting delivery and ending delivery of the medication at the same time . fluid chamber 462 will start its delivery after fluid chambers 456 and 458 start their delivery and fluid chamber 462 will end its delivery of medication after fluid chambers 456 and 458 end their delivery . fluid chamber 460 will begin its delivery of medication before fluid chambers 456 , 458 and 462 deliver their medication and fluid chamber 460 will end its delivery of medication after fluid chambers 456 , 458 and 462 end their delivery of medication . this arrangement allows the flexibility of delivering medications simultaneously or in any sequence desired . this is useful when medications that cannot be premixed are to be delivered simultaneously . in another sequence , fluid chamber 460 can be filled with saline that can be delivered simultaneously with and after the medications that are delivered from the fluid chambers 456 , 458 and 462 . fluid chamber 464 could then contain heparin as previously discussed . the cross - hatched areas 484 show the sections of the cartridge 440 that have been bonded together . this arrangement shows the flexibility of the invention as well as the simplicity of the invention that allows for the uncomplicated administration of medications to a patient . intermittent medications are prescribed using widely accepted medical infusion therapies that are fairly standard for adult patients with similar diagnoses . these standard medical therapies often call for multiple administrations of an infusion regimen each day and rarely change after they are prescribed . thus a prescription for an infusion regimen is similar to a prescription for an oral antibiotic in that the drug is taken a predetermined number of times per day for a predetermined time period . accordingly , an infusion patient generally receives a prescription for a particular medical infusion therapy that remains the same for several days . in accordance with the invention , the infusion prescription is filled by a pharmacist having a supply of infusion bags 20 having chambers with differing configurations . the pharmacist would provide the patient with the prescribed number of prefilled bags with the prescribed medication dosages . the following list is illustrative of the types of drug regimens that may be implemented in a bag in accordance with the invention . possible drug regimens and possible chamber configurations are not limited to those listed below or shown in the drawings . 5 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 1 gram ( g ) of cefazolin in 50 ml of 5 % dextrose in water -- given over 60 minutes ; and 5 ml of 0 . 9 % saline -- given quickly or over a few minutes . 3 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 1 g of cefazolin in 20 ml of dextrose ( d5w )-- given over 30 minutes ; 3 ml of 0 . 9 % saline -- given quickly or over a few minute ; 1 g of ceftazidime in 20 ml of dextrose ( d5w )-- given over 30 minutes ; 3 ml of 0 . 9 % saline -- given quickly or over a few minutes ; and 5 ml of 1000 units / ml of heparized saline -- given quickly or over a few minutes . 5 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 80 mg of gentamicin in 50 ml of 0 . 9 % saline -- given over 60 minutes ; 5 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 500 mg of ampicillin in 100 ml of 0 . 9 % saline -- given over 60 minutes ; 5 mls of 0 . 9 % saline -- given quickly or over a few minutes ; and 5 ml of 100 units / ml of heparized saline -- given quickly or over a few minutes . 10 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 1 g of vancomycin in 250 ml of 0 . 9 % saline -- given over 90 minutes ; and 10 ml of 0 . 9 % saline -- given quickly or over a few minutes . 3 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 1 g of cefazolin in 20 ml of dextrose ( d5w )-- given over 30 minutes ; 80 mg of gentamicin in 50 ml of 0 . 9 % saline -- given over 60 minutes ; 1 g of ceptazidime in 100 ml of 0 . 9 % saline -- given over 60 minutes ; and 5 ml of 0 . 9 % saline -- given quickly or over a few minutes . 500 mg of cafazolin in 20 ml of dextrose ( d5w )-- given over 30 minutes ; 500 mg of ceptazidime in 20 ml of 0 . 9 % saline -- given over 60 minutes ; and 50 mg of tobramycin in 50 ml of 0 . 9 % saline -- given over 60 minutes . kytril in 20 ml of 0 . 9 % saline given over five minutes ; and cisplatin in 100 ml of 0 . 9 % saline given over 30 minutes . 5 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 5 ml of 0 . 9 % saline -- given quickly or over a few minutes . 10 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 10 ml of 0 . 9 % saline -- given quickly or over a few minutes . 5 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 5 ml of 0 . 9 % saline -- given quickly or over a few minutes ; and 5 ml of 100 units / ml of heparized saline -- given quickly or over a few minutes . 5 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 5 ml of 0 . 9 % saline -- given quickly or over a few minutes . 5 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 5 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 5 ml of 0 . 9 % saline -- given quickly or over a few minutes . 5 ml of 0 . 9 % saline -- given quickly or over a few minutes ; 60 ml of drug # 1 -- given over 60 minutes tapered linearly beginning at a rate of 10 ml / hr and ending at a rate of 110 ml / hr . ; 5 ml of 0 . 9 % saline -- given quickly or over a few minutes . another embodiment of a fluid bag 90 , in accordance with the invention , is shown in fig1 , 14a , 14b and 14c . in this embodiment , the fluid bag includes a high - pressure clip 92 that is completely closed when the bag is in transport , preventing fluid from leaking from the bag or from moving between chambers . the clip includes a first bar 94 having two notched prongs 96 , and a second bar 98 having two corresponding sockets 100 for receiving the prongs . the bars may also include alignment holes 107 for specifically aligning the clip in the pump . the clip may be formed of metal or relatively rigid plastic and the two bars may be attached by a small wire or flexible plastic strip 101 . the prongs each have a dual position latch 102 which engages a ledge 104 in the socket . after the clip is closed to the second latch position , it closes the passage ways ( see fig1 c ) and cannot be opened with reasonable manual effort . the clip is engaged on the bag over the chamber passageways 108 , 110 , 112 and 114 through two clip holes 106 in the bag . the clip is automatically released and opened only when the bag is placed in an infusion pump of the invention , and the pump &# 39 ; s door is properly closed , the latch is automatically opened by the pump to a first open position ( see fig1 b ). in this embodiment , the pump also includes a low - pressure clamp . when the bag is properly placed in the pump and the door is properly closed , the low - pressure clamp or pad of the pumping device lays parallel next to the clip and seals off the chamber passageways 108 , 110 , 112 and 114 at a pad location 115 and simultaneously the clip is opened . the low - pressure clamp generates sufficient pressure to prevent any fluid flow through the chamber passageways until a minimum of pressure is applied to the chambers by the pump . when the pump generates enough pressure within a chamber , the fluid in the chamber is forced underneath and past the clamp through the corresponding chamber passageway to a common passage 116 which leads to the outlet port 118 . the bag may also include a pressure sensing dome 120 which is fluidly coupled to the common passage . the pressure sensing dome may be used to provide occlusion detection or pressure control . the pump pressurizes the bag in a linear sequence from the bag &# 39 ; s top to its bottom . again , because each chamber &# 39 ; s size and shape governs how the contents of each respective chamber will be administered , the bag may be configured to match the designed drug regimen . in this embodiment , the bag &# 39 ; s chambers can be filled with its base solutions ( diluent ) through the outlet ( and fill ) port 108 in the following manner . the high pressure clip 92 is released either by a special filling device which automatically releases the clip as the proper solution ( s ) are flowing into the bag or by a specially designed hand release device . additionally , the bag may include filling ports for each chamber ( not shown , see e . g ., fig1 ) and fluids or drugs may be added through these filling ports on an opposite side of the bag . fig1 a - 15d show another embodiment of a fluid bag 122 of the present invention . the bag is shown with four chambers 22 , 24 , 26 and 28 for implementing the sash infusion procedure . in this embodiment , the bag includes an integral connector 124 for coupling to an infusion tube ( not shown ). the integral connector allows the bag to be more integrated and simplifies the procedure for inserting the bag into an infusion pump . the bag further includes associated passageways 108 , 110 , 112 and 114 from each chamber to a common passageway 116 leading to the connector , a high pressure clip 92 , five alignment holes 40 , and a pressure sensing dome 120 . these components function as described in the previous embodiment shown in fig1 and 14a - 14c . fig1 shows another embodiment of a fluid bag of the invention . the bag 130 has features that are similar to the features of the bags discussed above and further includes fill openings 132 , vent openings 134 and frangible rupture seals 136 . thus , each of the chambers 22 , 24 , 26 and 28 has a fill opening 132 and a vent opening 134 . the vent part for the drug chamber 24 also includes a resealable or reusable port 138 for adding medication to the chamber . in this embodiment , the chambers are filled with the prescribed fluids through the fill openings 132 . air is allowed to escape through the vent openings 134 to prevent air bubbles in the chambers . then all of the openings , except the opening to the additional drug port 138 , may be sealed along seal lines 140 and 142 by a heat or ultrasonic seal or the like . an additional seal may seal the drug chamber 24 . the seal prevents the addition of additional drugs to the respective sealed chambers . the bag also features frangible rupture seals . as pressure is sequentially applied to the second , third and fourth chambers , respectively , the seal ruptures when the pressure in the corresponding chamber exceeds a predetermined threshold value . alternatively , the rupture seals may break at incremental increases in the applied chamber pressure such that when increasing pressure is applied to the entire surface of the bag , the rupture seals define the sequence of administration of the fluids in the chambers . the fluid bag of the invention may be filled by the bag manufacturer or by a pharmacist . the manufacturer may fill the bag &# 39 ; s chambers with saline solution , with other base solutions , or with the appropriate medications in a &# 34 ; form , fill and seal &# 34 ; or other manufacturing process . alternatively , the manufacturer may leave one or more chambers empty . the pharmacist would then complete the prescription using the fill ports . in yet another alternative , medication may be added to a bag through the fill port after the bag is inserted into a pump . the techniques for applying pressure to the bag may include a linear roller mechanism , a coiled spring mechanism , an air bladder , a series of platens , or other alternative methods . the pressurization technique is chosen in accordance with the designed embodiment of the bag and may be effected by a mechanical , electrical , chemical or other drive means , alone or in combination . apparatus for implementing representative pressurization techniques are discussed below . fig1 a and 17b show an embodiment of an infusion pump 150 for expelling the fluids from the chambers 22 , 24 , 26 and 28 of a fluid bag 152 of the invention . the infusion pump has compartment 154 for receiving the fluid bag . the compartment has a hinged door 156 which is shown in its open position in fig1 a . the hinged door includes a release latch 158 . at one end of the chamber are a roll - up roller 160 and an opposing roller 162 . the roll - up roller travels at a constant speed in conjunction with the opposing roller so that the rollers travel the length of the bag to sequentially compress the bag and sequentially force the fluid from the chambers toward the exit ports . the roll - up roller can be driven by a variety of means , e . g ., a spring drive mechanism housed in the enlarged side portion 163 of the pump which also functions as a hand grip . the hand grip is preferably covered with a &# 34 ; soft feel &# 34 ;, material . the fluid bag shown in fig1 a has three exit ports 164 , 166 and 168 that are coupled to an injection molded manifold 170 that functions as fill ports for the chambers and includes check valves . the solutions from the separate chambers are coupled to an exit tube 172 . the infusion pump 150 may have status indicators 174 for indicating the progress of the infusion . the pump may be an entirely mechanical device that may be operated by a spring mechanism . the pump may have a curved back surface 176 for ergonomically fitting again a patient &# 39 ; s body . fig1 a - 18c show another infusion pump 177 having an installed fluid bag for the administering the sash infusion procedure . this embodiment of the pump includes electronic control circuits and mechanisms for programmable control of the roller mechanism . programmable control allows the roller mechanism to operate at a variable rate . further , the roller mechanism may be stopped between chambers for a desired time interval . fig1 a shows a control panel 178 for one embodiment of the infusion pump 177 of fig1 a - 18b . the pump &# 39 ; s control panel has three buttons and four lights . the first button 180 is a start or run button for beginning the infusion procedure . the next button 182 is a stop or pause button to interrupt the infusion for a relatively brief pause . the third button 184 is a discontinue dose button for terminating the infusion . the lights indicate the status of an infusion and may be light emitting diodes , incandescent lamps , or the like . after the start or run button has been pressed and the roller is sequentially compressing the bag &# 39 ; s compartments , the running light 186 will be lit . if the pause button is pressed during the infusion procedure , the stopped / pause light 188 will be lit . when the infusion has been completed , the bag empty light 190 will be lit . an additional light 192 indicates whether an occlusion has occurred in the infusion line leading to the patient . fig1 b shows a control panel 178 for a second embodiment of the infusion pump 177 of fig1 a - 18c . the panel further includes , in addition to the buttons discussed above with respect to fig1 a , a clock 192 , a keypad 194 , and three dose select buttons 196 . the keypad may be used to enter a prescribed infusion therapy . the dosage buttons may be used to select various dose rates or administration times for a given bag ( or times for given chambers within a bag ) and corresponding drug therapy . another embodiment of the infusion pump mechanism for applying pressure sequentially across a bag 20 of the invention is shown in fig2 . the bag rests on a relatively rigid surface 200 . a pressurized bladder 202 is separated from the bag by a movable belt 204 . the bladder is sequentially released by the belt , thus applying sequential pressure across the bag . the belt accordingly replaces , for example , the function of the roller in the infusion pump of fig1 a and 17b . the speed at which the belt releases the bladder controls the pumping speed of the infusion pump . yet another embodiment of the infusion pump pressure mechanism is shown in fig2 . pressure is applied to the bag 20 by a series of inflatable bladders 206 . the bladders are inflated sequentially so that the series of bladders perform the same function as the rollers shown in fig1 a and 17b . a timer or a pressure sensor feedback mechanism ( not shown ) initiates the inflation of each subsequent bladder of the series of the desired time . another embodiment of the infusion pump pressure mechanism is shown in fig2 . the mechanism includes a series of bladders 206 that press a flexible pad 208 against the bag . the bladders are inflated sequentially and the flexible pad operates to smooth out pressure variations caused by the inflation of each individual bladder . an additional embodiment of the infusion pump , shown in fig2 , has a single bladder 210 that is pressurized after the bag is installed in the pump . the pump further includes valves configured to press against the respective passages of the chambers . the flow rate and sequence of fluids flowing from the chambers may be controlled by the valves , the applied pressure , and restrictive orifices to actively control the infusion process . fig2 shows a pump cartridge 410 inside one embodiment of a pump 400 . in this embodiment of the invention there is only one roller 402 that is held and guided by two slots 404 ( only one slot is shown ) to roll over the cartridge 410 . the roller is biased by a spring 406 to roll over the cartridge 410 and expel the fluids via exit port 408 . this embodiment can also use a motor and worm gear to drive the roller 402 over the cartridge 410 to dispense the fluid in the cartridge . the force applied to the roller by the motor and worm gear is controlled to produce the desired q for any given r , l and chamber geometry . fig2 shows the fluid chamber 409 having a top curved wall 407 and a relatively flat bottom wall 411 . however , depending on the materials used , both the top wall 407 and the bottom wall 411 can be curved , thus making a relatively symmetrical fluid chamber . fig2 shows one aspect of the invention in which a cartridge 414 with four chambers is placed in a vertically oriented rectangular hopper 412 . as the cartridge 414 &# 39 ; is fed through the rollers 418 and 420 , fluid is squeezed out of the cartridge 414 through line 408 . the rollers are driven by motor 428 via shaft 426 to clutch 424 which drives the shaft 422 that drives the rollers 418 and 420 . the clutch 424 is used to limit the maximum amount of force that can be applied to the rollers . the roller 418 is shown with optional tractor feed teeth 416 that can engage corresponding holes in the cartridge 414 for the purpose of applying a consistent force to the cartridge and preventing slippage of the cartridge when engaged by the rollers . while the foregoing has been with reference to specific embodiments of the invention , it will be appreciated by those skilled in the art that these are illustrations only and that changes in these embodiments can be made without departing from the principles of the invention , the scope of which is defined by the appended claims .
it is a primary object of the present invention to provide an automated system based on an integral fluid bag for administering a variety of intravenous drug regimens and reducing the vagaries of existing manual systems . the fluid has multiple chambers configured to implement a prescribed intravenous medical therapy . each chamber &# 39 ; s geometry , sequence and position , alone and in combination with the other chambers , matches the prescribed intravenous therapy or drug regimen . the bag &# 39 ; s configuration assures that the intravenous therapy is administered in accordance with the prescribed drug regimen , thus automating the previous manual method . a choice of fluid bag configurations may be stocked so that a prescription for well known and widely accepted drug regimens may be filled by merely selecting a bag with the appropriate chamber configuration and filling it with the prescribed medications .