referring to fig . there is shown a side elevational view of an exemplary embodiment of a medical solution container 10 provided in accordance with practice of principles of the present invention . the container comprises a collapsible bag or pouch portion 12 connected to a header portion 13 , from which inlet and outlet ports 14 and 15 , respectively , extend . an interior compartment 16 , in which a medical solution is stored , is defined within the pouch and header portions of the container . the container 10 is formed substantially as is described in u . s . pat . no . 4 , 484 , 916 , with the outlet port 15 modified in accordance with the invention . u . s . pat . no . 4 , 484 , 916 is incorporated herein by reference . in an exemplary embodiment , the header 13 is a molded thermoplastic material which has the appropriate properties of flexibility , durability , autoclavability , and inertness . such materials include polyolefins , particularly propylene - ethylene copolymers such as a polyallomer , provided by eastman kodak under the designation &# 34 ; m753 - 296e ,&# 34 ; blended with 10 % by weight of a styrene butadiene elastomer sold by shell chemical company under the trademark &# 34 ; kraton .&# 34 ; the bag portion 12 comprises two sheets or films of thermoplastic material , heat - sealed to each other along their side and bottom marginal areas or edges 18 and 20 , respectively , and heat - sealed to the header 13 along their top marginal areas 22 . the end 24 of the container 10 opposite from the header 13 is provided with an opening 26 to facilitate suspension of the container from a hook of a conventional iv stand ( not shown ). the inlet port 14 is provided for injecting additives ( e . g ., medication or nutrients ) into the contents ( such as a prepackaged dextrose solution ) of the container 10 . the port 14 has an opening or channel 28 leading to the contents of the container 10 , and a resilient self - sealing stopper ( not shown ) is mounted on the port upstream from the opening 28 , through which the additives are injected . suitable inlet ports are described in u . s . pat . no . 4 , 484 , 916 . the outlet port 15 may be referred to as a set port because it can be used to couple the container 10 to a conventional administration set . as is well known , such an administration set includes a hollow spike ( 34 in phantom in fig3 and 4 and in detail in fig5 ) that is inserted into the set port . such a spike is frictionally retained by the set port in order that the container 10 may be inverted and suspended , and its fluid contents withdrawn and administered intravenously to a patient . the outlet port 15 can be provided with a sealing disk and a tear - off cap combination ( not shown ), both of which would be removed prior to insertion of the spike into the port . the sealing disk and cap , which are provided to seal the port 15 to maintain the sterility of the interior of the port prior to use , and which need not be described in any detail to understand the invention , are removed prior to insertion of the spike 34 into the port 15 . the port 15 includes a projection 32 , which is used in conjunction with the sealing disk and cap arrangement . with reference to fig3 and 4 , the set port 15 provided in accordance with this invention is shown with the spike 34 , located at two different positions during the spike insertion process . the port 15 comprises a hollow tubular neck portion 36 forming an elongated channel 38 with an axis 40 ( the longitudinal axis ) along its length . the set port 15 and its channel 38 are shaped and dimensioned for receiving and frictionally holding the spike 34 . in one preferred embodiment of a set port 15 provided in accordance with this invention , the neck 36 is formed integrally with the header 16 and includes a lower wall portion 42 with an enlarged cylindrical bore 44 and a central wall portion 46 defining a coaxial cylindrical bore 48 , which has a smaller internal diameter than the bore 46 . the transition between the bores 44 and 48 forms a downwardly - facing planar ledge 49 . a tapered , annular , resilient collar 50 is formed integrally with the neck 36 and extends upwardly from the central wall portion 46 . the collar 50 has an inner surface 50a that merges with the surface of the bore 48 , and an outer surface 50b . both the inner surface 50a and outer surface 50b slope inwardly ( toward the longitudinal axis 40 ), terminating in a circular lip 50c , which defines the opening 51 of the set port . the diameter of the opening 51 is smaller than the internal diameter of the reduced cylindrical bore 48 . consequently , a spike 34 , which has an outside diameter that is smaller than the diameter of the bore 48 but larger than the diameter of the opening 51 , will engage the collar 50 to cause limited expansion thereof . the spike will be retained , at least in part , by the tensioning of the collar about the spike . this engagement also serves to form a seal . the set port neck 36 includes a pierceable diaphragm 54 , which extends across and seals the channel 38 . in an exemplary embodiment , the diaphragm is formed integrally at the junction of the central wall portion 46 and the lower wall portion 42 , substantially in the plane of the ledge 49 . in accordance with practice of the present invention , the diaphragm 54 is slanted or tilted , i . e ., it lies substantially in a plane which is at an angle c to a normal 55 ( shown in fig3 and 4 , in phantom ) to the insertion direction a . said another way , the diaphragm 54 lies in a plane which is at an angle c to the normal of the axis 40 or to the insertion direction a of the spike 34 . in an exemplary embodiment , where the bore 48 is about 1 / 4 inch in diameter , diaphragms having a thickness in the range of 0 . 005 - 0 . 009 inch are preferred for the material specified herein for the header and associated diaphragm . the result of having a diaphragm inclined at an angle , such as the angle c , is that the peak or maximum insertion force needed to push a spike through the diaphragm is decreased , compared to the peak force required for insertion of a spike through a comparable diaphragm which is not at an angle , i . e ., which is in a plane normal to the axis 40 . fig7 graphically shows the variation in ( 1 ) the peak force required to insert a spike ( configured like the spike 34 ) into the outlet port 15 of fig3 and 4 , manufactured from the blend of polyallomer and kraton described herein , and ( 2 ) the force required to retract the spike therefrom , as a function of diaphragm angle . while the plot 101 of insertion force is seen to progressively diminish as the diaphragm inclination angle c is increased , the plot 103 of retraction force peaks at an angle c in the range of between 5 ° and 15 °. when the angle c is less than about 5 °, the reduction in insertion force is minimal compared to the reduction at larger angles , and the retraction force is relatively low . the retraction force also falls below its maximum when the angle c exceeds about 15 ° and falls substantially below its maximum when the angle c reaches 20 °. accordingly , for the outlet port material described herein ( the blend of polyallomer with 10 % kraton ), the preferred range within which the inclination angle of the diaphragm should be kept , is from about 5 ° to about 20 °, and preferably at about 15 °. of course , with different materials and / or spike dimensions , the optimum range of angles may be wider , narrower , or displaced from that shown . the spike insertion process will be described in more detail following a description of a typical spike 34 , shown in a partial cutaway and vertical sectional view in fig5 . the spike 34 has a cylindrical shaft 60 terminating in a tapered , and shown here as conical , tip 62 , with a point 63 on its end . a circular junction 64 is defined by a line of transition which extends around the spike between its cylindrical shaft and tip portions and which falls in a plane which is normal to the longitudinal axis of the spike . the spike 34 has a top section 66 to which iv tubing ( not shown ) is connected and which includes a shoulder 68 on its bottom . two vertical apertures 70 are formed in the spike , extending from the top section 66 for communication with iv tubing , through the conical tip section 62 for communication with the interior compartment 16 of the container 10 . ( it should be emphasized that the advantages of the invention are not limited to the particular spike described herein .) with renewed reference to fig3 and 4 , the spike 34 is inserted into the outlet port 15 in the direction a . as the tip 62 enters the channel 38 , its conical wall bears against , and spreads open , the annular collar 50 . when the spike tip 62 has moved past the lip portion 50c of the collar 50 , so that the spike &# 39 ; s cylindrical shaft 60 engages and begins passing through the collar lip 50c , the collar 50 is spread to its widest position , as is shown in dashed lines . as insertion continues , the point 63 of the tip 62 meets the slanted diaphragm 54 and pierces and ruptures it . the ruptured diaphragm 54 is folded downward and outward as the tip 62 passes through . fig3 illustrates the instant when the circular junction 64 between the spike &# 39 ; s cylindrical shaft 60 and conical tip 62 first engages the ruptured diaphragm 54 and , more particularly , the diaphragm &# 39 ; s peripheral junction with the bore 48 , which runs along an elliptical path due to the inclination of the diaphragm . the initial engagement between the circular junction 64 of the spike 34 and the diaphragm &# 39 ; s periphery occurs at a point 76 on the diaphragm , which is the portion of the diaphragm nearest the opening 51 . the internal diameter of the bore 44 below the diaphragm 54 is larger than the internal diameter of the bore 48 above the diaphragm , so that , as the spike 34 ruptures the diaphragm , the diaphragm material tends to fold or roll downwardly and outwardly , and is accommodated in the space 77 ( best seen in fig4 ) around the inside circumference of the bore 44 . as the insertion of the spike 34 continues , the junction 64 contacts the remaining portion of the diaphragm , with the contact point moving outwardly , in both directions , away from the initial contact point 76 , around the circumference of the diaphragm . as the insertion process continues , the junction 64 contacts and pushes through the diaphragm at its lowest point 78 , i . e ., the point on the diaphragm furthest from the opening 51 . the cylindrical shaft 60 pushes the ruptured diaphragm material against the interior surface of the wall 42 in the enlarged bore 44 . as can thus readily be appreciated by one of ordinary skill in the art , it is preferred that the enlarged bore have a radius equal to or greater than the radius of the reduced bore 48 by at least the thickness of the diaphragm 54 to provide for accommodation of the diaphragm wall , so that jamming of the spike is inhibited . the insertion process ends , i . e ., the spike is fully inserted , when the shoulder 68 ( fig5 ) of the spike 34 meets lip 50c of collar 50 . as is well known in the art , the spike and the set port are dimensioned so that , at this point , the channels 70 are open into the interior compartment 16 of the container 10 . in addition , the spike 34 must be retained in the set port so that container 10 can be inverted . in the set port provided in accordance with the present invention , the force retaining the spike 34 in the port 15 results both from frictional engagement of the spike 34 with the ruptured diaphragm 54 and from the frictional engagement between the spike and the collar 50 . from the above description of the insertion process , significant advantages of the invention over conventional set ports are evident . in particular , an important advantage of the invention is that the peak or maximum force required to insert the spike is reduced , as compared to the peak force required with a set port having a conventionally oriented diaphragm . in such a conventional set port , a large increase in insertion force is required ( the peak force ) when the cylindrical shaft of the spike meets the diaphragm , because the entire circumference of the diaphragm is contacted at the same time by the entire circumference of the junction 64 between the conical point and cylindrical shaft of the spike . this occurs with conventionally - oriented diaphragms because both the junction 64 of the spike and the line along which the diaphragm is attached to the junction of the wall portions of the port lie in planes which are normal to the insertion direction of the spike . as the material at the circumference of the diaphragm is supported by the set port wall , it is difficult to bend downward , particularly when it must bend all at once , as is the case when prior - art diaphragm configurations are used . requiring the circumferential diaphragm material to be pushed or bent downwardly at the same time causes the sharp rise in the insertion force . conversely , the use of a slanted diaphragm in accordance with the invention results in a the required peak insertion force being relatively less . this is due to the progressive engagement of the junction 64 with the diaphragm , so that the circumferential diaphragm material is not contacted and bent downwardly at the same time . the reduced peak insertion force resulting from the arrangement of the present invention promotes complete penetration of the diaphragm by the spike . such complete penetration is important to ensure that the ruptured diaphragm participates fully in retaining the spike 34 within the outlet port . as noted above , when in use , the iv bag is suspended port end down , so the spike will be pulled downward by gravity and by the downward pressure from the iv liquid flow , as well as by any forces created by jostling of the iv tubing . without proper frictional retention , fluid may leak or the spike may become disengaged and fall out of the set port . either of these events can waste the iv bag and its contents and contaminate the spike . a second embodiment of the invention is shown in fig6 . most of its elements are similar to corresponding elements in the outlet port of fig3 and 4 and bear the same reference numerals except for being incremented by 100 , so that , for example , the neck 36 of fig3 and 4 appears as the neck 136 in fig6 . in accordance with the invention as implemented in the port of fig6 the diaphragm 154 comprises a relatively thick , peripheral , ring portion 154a and a relatively thin , central portion 154b . for a bore 148 diameter of 0 . 25 inch , suitable thicknesses for the thin and thick regions 154b and 154a are in the ranges of about 0005 - 0 . 009 inch and 0 . 020 - 0 . 030 inch , respectively . the advantage of this embodiment is that , with the diameter of the thin portion 154b just slightly smaller than that of the spike 134 ( by from about 0 . 010 to about 0 . 020 inch ), the retraction force is greater because the thick , peripheral ring portion 154a grabs the spike 134 as it is being withdrawn . while in the foregoing , embodiments of the invention have been disclosed in considerable detail for purposes of illustration , it will be understood by those skilled in the art that many of these details may be varied without departing from the invention as defined by the appended claims .
a medical solution container includes a bag portion for storing solution and a header portion which incorporates an improved outlet port in communication with the bag portion for receiving and holding a spike from an administration set . the outlet port has , at a distal end from the bag portion , a generally inwardly inclined tapered annular collar which , at its widest diameter portion , joins a substantially cylindrical coaxial bore section . the cylindrical bore section has a first section with a reduced diameter which adjoins a second section having an enlarged diameter . the second section is located at an end of the outlet port proximate the bag . a pierceable diaphragm for sealing the outlet port is supported at the junction of the reduced and enlarged diameter bore sections and lies substantially in a plane which is at an angle to a normal to the insertion direction of the spike or the axial direction of the cylindrical bore . by providing the diaphragm at an angle , which is preferably between about 5 ° and about 20 °, the force required to pierce the diaphragm with the spike is reduced while a reliable holding force is maintained after the spike has been inserted , to frictionally hold the spike in the outlet port .