Abstract:
The present invention provides a breastshield for use in a breastpumping system for expressing milk, the breastshield being of such a construction that substantially limits the amount of air between the breast/nipple and the breastshield surrounding the breast/nipple, and most preferably virtually eliminates any air at least in the area of the breast and nipple. In some embodiments, any air in the breastpumping system is substantially eliminated. With the amount of air limited, the mechanism used for generating the pressure difference in the breastshield (e.g., vacuum or negative pressure), such as a diaphragm pump, does not need to do as much work. Less energy is required for the expression of milk, and thus the size of pump used can be decreased, thereby reducing the overall cost of the device.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a divisional of U.S. patent application Ser. No. 12/885,145, filed Sep. 17, 2010, which claims priority to provisional application Ser. No. 61/244,636 filed on Sep. 22, 2009. This application is also related to U.S. patent application Ser. No. 13/742,502, filed Jan. 16, 2013. The entire disclosure contents of these applications are herewith incorporated by reference into the present application. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates generally to breastmilk pumps, and particularly to an improved breastpump assembly for expressing mothers&#39; milk, which in one significant aspect, substantially eliminates any “dead volume” in pumping, especially in the area of the breast and nipple. 
       BACKGROUND 
       [0003]    Breastpumps are well known, and generally are comprised of breastshields (also referred to as hoods) that fit over the breast, a vacuum pump connected to the breastshield for generating an intermittent vacuum within the breastshield, and a receptacle for the milk that is pumped from the breast. Manually driven vacuum pumps are commonplace, as well as those that are driven by a motor (house current, battery, pneumatic, etc.). 
         [0004]    The vacuum pumps of these devices intermittently generate a vacuum (or negative pressure) within the breastshield, with the breastshield covering the nipple and typically a substantial amount of the breast itself. The intermittent suction action of the pump serves to pull on the nipple, and so express milk, in an action that some have considered similar to suckling. The milk so extracted ordinarily flows from the breastshield into a collection container, e.g., a bottle, for storage and later use. A breastpump of the foregoing description is shown in U.S. Pat. Nos. 4,857,051, and 4,929,229, and reference thereto may be made for further detail on breastpumps in general. A recent advancement in these types of breastpumps is also disclosed in US Patent Publication 2008/0171970. 
         [0005]    Breastshields typically have a funnel-shape, comprising a conical portion with a tubular extension, the latter sometimes referred to as the nipple tunnel. The nipple and surrounding breast are received in the conical portion, with the nipple often extending into the tubular extension. Under vacuum, the breast is pulled further into the breastshield, ordinarily with the nipple then being pulled into the tubular extension, with the surrounding breast thereby also typically being pulled further into the funnel. 
         [0006]    A nursing mother&#39;s nipples may thus be forced against the wall of the nipple tunnel under vacuum. This may cause friction against the wall as the nipple moves deeper into the nipple tunnel. There can also be friction between the breast and the conical portion, as well as in the nipple tunnel. This is actually a back-and-forth movement under the intermittent vacuum, exacerbating the effects of the frictional engagement. 
         [0007]    Researchers, particularly those working with Medela, have studied the manner in which infants breastfeed, and have come to seriously question the “conventional wisdom” on how a baby feeds from the breast. For instance, it appears that a vacuum instead of a stripping action is occurring during milk expression. Further, nipple placement is proximal to the hard/soft palate junction rather than at the junction. Ultrasound imaging shows that there is little to no air in the natural “system” when the infant is nursing. In other words, when the infant is latched onto the mother&#39;s breast, there is little to no air in the infant&#39;s mouth. The suckling action by the baby seems to radially compress as well as expand (or release some compression) the nipple; the nipple attempts to expand into the volume created as the baby&#39;s tongue moves away from the palate. 
         [0008]    In contrast, in commercially available breastpumps used by mothers for expressing or extracting breastmilk for later use by the infant, air is present in the system, specifically in the breastshield into which the breast is placed. Once a mother&#39;s breast is in place, the pump must work not only to express the breastmilk from the breast but also must work to move the air in the system as well. This, understandably, affects the size of the pump, and the energy required to make the pump work. 
         [0009]    Another observation of researchers is that, during nursing, the baby latches onto the mother&#39;s breast and the baby&#39;s tongue has continual contact and interacts with the nipple of the breast to bring about the flow of milk. In commercially available pumps, once the breast is inserted into the breast cup or shield, the vacuum generated by the pump typically pulls the breast further into the breastshield, ordinarily with the nipple then being pulled deeper into the tubular extension. The nipple tends to be more or less “free” within the nipple tunnel, except to the extent it may be pulled into contact with the nipple tunnel wall (or expands to fill the tunnel diameter because of the applied vacuum). When compared to nursing, the expression of milk with a breastpump of this conventional design can bring about some discomfort to the mother, and does not entirely duplicate the feel and conditions present in normal suckling. 
         [0010]    Further, with the available breast pumps, a mother generally is in a substantially vertical position while pumping, and the bottle into which the breastmilk flows must be located in a position downwardly from the mother. This is because conventional breastpumps operate using gravity as the prime mover to move milk from the breastshield to the bottle. This limits the mother&#39;s activities while pumping; for example, she cannot recline to any great extent while pumping. 
       SUMMARY 
       [0011]    Embodiments of the present invention provide a breastshield for use with a breastpump for expressing milk, the breastshield being of such a construction that substantially limits the amount of air between the breast/nipple and the breastshield surrounding the breast/nipple, and most preferably virtually eliminates any air at least in the area of the breast and nipple. With the amount of air limited, the mechanism used for generating the pressure difference in the breastshield (e.g., vacuum or negative pressure), such as a diaphragm pump, does not need to do as much work. Less energy is required for the expression of milk, and thus the size of pump used can be decreased, thereby reducing the overall cost of the device. 
         [0012]    The vacuum pump can therefore be configured to be smaller and lighter, which means that it is in turn less conspicuous to onlookers. The mother can use the vacuum pump more discreetly. In addition, because of the lower energy, the vacuum pump is quieter during use, which in turn increases the comfort and discretion. 
         [0013]    One aspect of the small working volume of the invention includes utilizing sensing of the vacuum pressure applied to the nipple and processing the vacuum level reading, as through a microprocessor control system, for example. The microprocessor then drives the pump in a manner to ensure the appropriate vacuum profile is produced at the nipple. This will allow the invention to perform consistently from mom to mom and will also allow for an improved reproduction of vacuum profiles of an infant. A vacuum regulator could similarly be used. Such sensing or regulation could further be useful in maintaining a baseline vacuum or minimum vacuum at the nipple, which remains throughout the pumping session. 
         [0014]    Movement of the nipple can thereby be limited, and the amount of air in the system reduced or virtually eliminated, especially in embodiments of the present invention for the expression of milk including a baseline vacuum. A baseline vacuum would be one that is maintained during some or all of a pumping session, such that the pressure seen at the nipple does not return to ambient, but remains at, say, a pressure of approximately −20 to −50 mmHg, before returning to a greater vacuum during milk extraction. Reference can be made to U.S. Patent Publication No. 2008/0255503 entitled “Method and Apparatus for Minimum Negative Pressure Control, Particularly For Breastpump With Breastshield Pressure Control System,” filed on Apr. 11, 2007, which is incorporated by reference herein in its entirety, for further detail on such “baseline vacuum.” 
         [0015]    Further, with the breastshield of the present invention, vacuum may act on a smaller portion of the mother&#39;s breast, indeed on the nipple alone, as compared to known breastshields. Specifically, the breastshield of the present invention in one aspect constrains the nipple of the breast, and provides contact surrounding a significant portion or substantially all of the nipple, more closely duplicating conditions in normal breastfeeding. 
         [0016]    The reduction of air in the area of the nipple, or further in the entire system can range from substantially no air (“zero dead volume”), or substantially no air after initialization (i.e., air is largely or completely eliminated in the working volume after one or more initial cycles); or a small volume of air remains, but still achieving one or more of the inventive objectives. This reduction of air can consist of an initially larger opening which subsequently conforms more closely to the nipple to reduce the air volume around it. Embodiments include, but are not limited to, the use of inflating seals, self expanding seals, fit adjustment mechanisms, as well as custom fit openings. 
         [0017]    In an embodiment of the invention a vacuum is applied just to the end of the constrained nipple. Embodiments for the constraint of the nipple include either longitudinal, radial, or both radial and longitudinal limitation to nipple movement. Such constraint will limit the expansion of the nipple from applied negative pressure, resulting in improved comfort. Again, as used herein, this “expansion” could be an extension of the nipple from its rest shape, or in the sense of going from a compressed condition to a less compressed condition. 
         [0018]    Another attribute or aspect of the invention is providing embodiments that closely surround the nipple and adjacent breast with part of a lateral sidewall (or walls) of the breastshield that are designed to be reminiscent of the tongue of the baby. That is, this sidewall structure is then made to move radially relative to the breast/nipple. This in turn moves the breast/nipple outwardly (i.e., expanding it), which is believed to be much more like what an infant&#39;s suckling actually does. 
         [0019]    Several embodiments of the invention include the use of low durometer materials to simulate the soft tactile feel and function of the inside of a baby&#39;s mouth. 
         [0020]    As well, this invention comprises embodiments where a separate suction source or sources may be applied to the end of the nipple for the expression of milk. In this aspect the constraint of the nipple serves to provide the benefits of comfort and tactile sensation, as well as provide a sealing element at the base of the nipple to further reduce the working volume of air. 
         [0021]    In an aspect of the invention, more of a radial force is applied to the nipple than a longitudinal force, i.e., the nipple is subjected to a force that tends to enlarge the nipple radially, and then compress or return the nipple as the breastshield returns to an initial condition. This expansion of the breastshield can be used to create the suction pressure to express milk, reducing or eliminating the need for a second vacuum source. 
         [0022]    Several embodiments of the invention include an expansion of the nipple during the vacuum rise portion of a vacuum cycle. When the vacuum is returned to an ambient or baseline level, the nipple is relaxed or even somewhat compressed. 
         [0023]    An embodiment of the invention includes not expanding the nipple beyond its natural diameter. 
         [0024]    Another aspect of the invention is an apparatus and method for improved breastfeeding by compressing the nipple asymmetrically, i.e., out-of-round. In a conventional pump, the nipple is drawn into a structure (e.g., nipple tunnel) which has a circular cross-section. It is considered an advantage herein to provide a structure where the nipple is subjected to a radial force that presses it into a more elliptical cross-section. 
         [0025]    In addition to the lateral or longitudinal constraint described above, an aspect of the invention includes the further constraint of the nipple from lateral movement, including utilizing a physical constraint of movement at the distal end of the nipple. The location of this physical end constraint can be adjusted to an individual. The end constraint may further consist of a porous cover to allow milk and pressure transfer through it, such as a porous membrane, valve, or orifice structure. 
         [0026]    While an objective of the invention is to minimize the “dead volume,” with some embodiments even substantially eliminating “dead volume” throughout the entire system, it is readily apparent that the invention described has advantages not limited to the foregoing, such that the system might have a large or typical air volume away from the proximal location of the nipple, but just include the elements of nipple constraint to gain the benefits of comfort and effective milk expression. 
         [0027]    Embodiments of the invention can also readily utilize any of the nipple contact surfaces to provide a tactile stimulation to the nipple, further improving comfort and enhancing milk ejection. This includes the use of tactile features on the contact surfaces, and alternately includes driving of the contact surfaces with a force to apply a stimulation to the nipple, either in sync with or unrelated to the vacuum cycle. 
         [0028]    In addition, due to the substantial elimination of air from the system of the present invention, the mother is not required to be in a substantially vertical position while expressing milk; further the container into which the expressed breastmilk flows does not need to be located downwardly with respect to the mother. An embodiment provides for a system which actively forces liquid to move, and is not reliant on gravity. The expressed milk moves through the breastpump assembly to the container provided, regardless of its location with respect to the mother. This provides flexibility for the mother in the type of activities in which she can participate while expressing milk. It also allows the breastpump assembly conduit structure, and even the container into which the expressed milk is collected, to be located other than downwardly with respect to the mother&#39;s breast. As well, the container may be of a type, such as an expandable container, that is normally closed or compressed and can be expanded by the expelled milk as the container is filled. As a result, the milk can be expressed independently of the relative orientation of the breastshield, the milk collecting container, and the vacuum pump with respect to one another. The mother may, for example, even express milk while lying down. This is particularly optimal in a “hands-free” embodiment since the mother may even bend down and in general move more freely. 
         [0029]    Another embodiment of the invention has the mother&#39;s milk routed, at least in part, into the channel through which the vacuum, or working fluid, is initially operating on the breastshield. The milk thereby replaces the “air” (vacuum) in this part of the system, turning it from a pneumatic system to a hydraulic system. This is considered to increase the efficiency. That is, this reduces the work that the pump needs to do to achieve the effective vacuum level, and thus increases the efficiency of the system. A further salutary benefit is that the mother&#39;s own milk can now be used to warm the shield. 
         [0030]    Another embodiment of the invention utilizes a sheath-like membrane which is emplaceable over a funnel-shaped or other breast-receiving shaped shield part, thereby forming a liner to the shield part. The sheath-like membrane is adapted to closely surround the nipple, achieving objectives of greatly eliminating air volume surrounding the breast/nipple and improved tactile sensation. The sheath-like membrane can also be made disposable, providing an additional benefit. 
         [0031]    These as well as other aspects and advantages of the invention will become further apparent to those of skill in the art by reading the following detailed description, with reference where appropriate to the accompanying drawings. It should be understood that the embodiments described herein are intended to illustrate the invention by way of example only, and are not limiting. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0032]    Exemplary embodiments of the invention are described herein with reference to the drawings, in which: 
           [0033]      FIG. 1  is a perspective view of an embodiment of the present invention; 
           [0034]      FIG. 2  is a side elevational view of the breastshield part shown in  FIG. 1 ; 
           [0035]      FIG. 3  is a front end view of the breastshield shown in  FIG. 2 ; 
           [0036]      FIG. 4  is a front end view of the breastshield shown in  FIG. 3 , with a sheath partly detached from the breastshield; 
           [0037]      FIG. 5  is a sectional view in elevation of an embodiment like that of  FIG. 1 ; 
           [0038]      FIG. 6  is a schematic view in section showing another embodiment of the inventive breastshield using two sources of pressure (here, vacuum); 
           [0039]      FIG. 7  is a schematic view in section of yet another embodiment of the inventive breastshield showing a system having a valve member capable of maintaining a baseline vacuum in the breastshield; 
           [0040]      FIG. 8  is yet another embodiment of the inventive breastshield in sectional view; 
           [0041]      FIG. 9  is a front end view of the breastshield of  FIG. 8 ; 
           [0042]      FIG. 10  is a rear end view of the breastshield of  FIG. 8 ; 
           [0043]      FIG. 11A  is a modified version of the embodiment of  FIG. 8 ; 
           [0044]      FIG. 11B  is another modified version of the embodiment of  FIG. 8 ; 
           [0045]      FIG. 12  is still a further embodiment of the inventive breastshield in sectional view; 
           [0046]      FIG. 13  is a rear end view of the breastshield of  FIG. 12 ; 
           [0047]      FIG. 14  is another embodiment of the inventive breastshield in sectional view, shown in a first position; 
           [0048]      FIG. 15A  is a partial view of the embodiment of  FIG. 14  in a second position; 
           [0049]      FIG. 15B  is a view like that of  FIG. 15A , showing the valving in an inverted (upward) position, and with a pressure sensor; 
           [0050]      FIG. 16  is still another embodiment, this one shown schematically in section and elevation; 
           [0051]      FIG. 17  is the embodiment of  FIG. 16 , with a nipple ring being enlarged; 
           [0052]      FIG. 18  is a figure similar to that of  FIG. 16  of an embodiment having a nipple cap carried by a movable wall; 
           [0053]      FIG. 19  is the embodiment of  FIG. 18  with the nipple cap attached about the nipple; 
           [0054]      FIG. 20  is yet another embodiment using a figure like that of  FIG. 18 , employing a nipple cap and a nipple cover; 
           [0055]      FIG. 21  is a schematic of a drive mechanism for use with the breastshield shown in  FIG. 14 ; and 
           [0056]      FIG. 22  is another example of a drive mechanism for use with the breastshield shown in  FIG. 14 . 
       
    
    
     DETAILED DESCRIPTION 
       [0057]      FIG. 1  depicts a first system for expressing breastmilk in accordance with the present invention. The system includes a breastshield  10  attached to a base  12 . Base  12  is part of a breastpump assembly more particularly shown in US Patent Publication 2008/0171970, the disclosure of which is incorporated herein by reference. That assembly includes a vacuum pump which utilizes a barrier component (see  FIG. 5 ) or diaphragm  14  that is enclosed in a clamshell-like chamber made of a front housing  18  and a rear housing  16 . The barrier is reciprocated within the space of the housings  16 ,  18  by an intermittent vacuum from a vacuum source (not shown) which is connected via a tube  20  (see  FIG. 1 ). Movement of the barrier downstream by the vacuum source conveys vacuum upstream by its movement (expanding the volume upstream). 
         [0058]    Milk extracted in operation flows to a container  22  attached to a collar  24  which communicates with conduit structure within the breastshield assembly. Again, the details of this breastshield assembly and breastpump can be gleaned from the foregoing patent publication. As will be well appreciated, this embodiment using the foregoing pump of  FIGS. 1-5 , while substantially eliminating any residual air in the immediate vicinity of the nipple, as will be shortly described in detail, still will contain a volume of air on either side of the barrier (diaphragm), and especially in the tubing extending to the vacuum source. The present invention not only contemplates substantially eliminating the “dead volume” of air at the nipple, but in other embodiments (see, e.g.,  FIGS. 14, 15A, 15B  and  FIGS. 21-22 ), the virtual elimination of the “dead volume” in the entire system. 
         [0059]    As can be seen in  FIG. 1  and in further detail in  FIGS. 2 and 5 , the breastshield  10  includes a funnel or conical portion  26 , a tubular extension or nipple tunnel  28  extending therefrom, and a valve  30  provided at the downstream end of the tubular extension  28 . The terms funnel and conical are being used herein with reference to the more traditional shapes of breastshields, which are adapted to receive the nipple and surrounding breast therein. As is evident herein, however, the breast receptacles of many of the embodiments no longer employ a true “funnel” or “cone” geometric shape. 
         [0060]    The lack of a large volume funnel accommodates a wide range of breast sizes and types and minimizes the potential dead volume in the funnel and nipple tunnel area. The valve  30  used in this version is a duckbill valve. It is mounted in a solid ring  32 , which closes the end of the tubular extension  28 . 
         [0061]    The breastshield of the present invention is further provided with a sheath-like member  34 , which functions in part as a liner for the funnel part of the breastshield  10  (portion  26  and nipple tunnel  28 ). The sheath member  34  has a rim part  36  that fits around and secures the widened mouth of the sheath member to the outer circumference of a rim  38  of the shield portion  26  (see  FIGS. 3 and 4  in particular). Shield portion  26  and nipple tunnel  28  thereby form a frame for the sheath member  34 . 
         [0062]    The sheath member  34  is connected at its downstream end  40  about the upstream end of the duckbill valve  30 , sealing around that valve on a downstream edge surrounding the valve. As can be seen in  FIG. 5  in particular, the sheath member  34  is also somewhat funnel-like in shape, being placed into some stretched tension (i.e., taut) through the foregoing mounting arrangement. This serves to pull the sidewalls of the sheath member  34  away from the inner sidewall  42  of the breastshield  10  (much like stretching an unfilled balloon). The sheath receives the nipple of the breast in use, and snugly holds the nipple and some adjacent breast in a supple embrace. The sheath  34  is made of silicone rubber in a relatively thin thickness, again, much like a thick balloon. As can be seen from  FIG. 4 , the sheath can be easily removed from the breastshield, being shown partially peeled back from the underlying shield to which it is mounted. This provides an additional benefit, in that the sheath member  34  can be made disposable. 
         [0063]    Note that in this embodiment, the sheath member  34  yields a nipple receiving inner tunnel  44  which is out-of-round, i.e., not of a circular cross section (see  FIG. 3 ). Here, it is somewhat elliptical. This provides a radial force to the nipple which tends to flatten the nipple on opposite sides, toward an elliptical shape. 
         [0064]    It will be noted that  FIG. 5  has a slightly different shape from that of  FIGS. 1-4  in the area of the portion  26 . This simply shows an application that is more of the traditional conical or funnel-shape for the breast-receiving part of the breastshield. 
         [0065]    During expression, the breast, and primarily the nipple of the breast, is inserted into the mounted sheath member  34 . Vacuum is applied from the vacuum source (pump) via the tube  20 , with the vacuum conveyed to the breastshield by action of the barrier  14  within the clamshell-like chamber. The vacuum evacuates an antechamber  46  within the base  12 , and is further conveyed into the space  48 , thereby forming a plenum between the sheath member  34  and the inner sidewall  42  of the shield via a channel  50 . As can be appreciated from  FIGS. 2 and 5 , the vacuum is thus applied on the distal end of the nipple via outward radial movement of the sheath member  34  as it expands, and through the valve  30 . This in turn pulls upon the nipple constrained in the sheath member. This applies, in part, an outward force (referred to herein as “radial”). The sheath member  34  substantially limits the amount of air in the system. Essentially, there is only air initially located between the nipple and the valve that is involved, along with air in the antechamber  46 . 
         [0066]    Milk expressed into the downstream end of the sheath member  34  passes through the duckbill valve  30 , where it is conveyed through internal conduit structure to the bottle  22 . Note that the duckbill valve can be structured so that a preset vacuum level is maintained within the sheath member, such as at a minimum pressure (vacuum) of approximately −20 to −50 mmHg, for instance. A one-way duck bill valve  30  is used herein, but other equivalent types of valves can be used. Again, reference can be made to U.S. Publication No. 2008/0255503 regarding such a “baseline” vacuum concept and its effectuation. 
         [0067]      FIG. 6  is yet another embodiment of a system for expressing breastmilk that uses two sources of pressure, here vacuum. The system includes a breastshield  52  which would be attached to the base  12  of  FIG. 1 . Base  12  is part of a breastpump assembly more particularly shown in US Patent Publication 2008/0171970, described above with the first embodiment. Milk extracted in operation flows to the container  22  attached to a collar which communicates with conduit structure within the breastshield assembly. Again, the details of this breastshield assembly and breastpump can be gleaned from the foregoing patent application. 
         [0068]    As can be seen in  FIG. 6 , this embodiment of the invention has a breastshield  52  with a receptacle portion  54 , an inner side wall  55 , a tubular extension or nipple tunnel  56 , and a downstream end  66  with a plurality of openings  58 . This embodiment has an outer sidewall  60  that is somewhat rigid (or relatively less collapsible than the inner sidewall  55 , as will hereafter be made apparent). For example, the inner sidewall  55  could be similar to the foregoing sheath-like member  34 . There is a first port  62 , and a second port  64 . The inner sidewall  55  includes the downstream end  66 . 
         [0069]    The first port  62  and the second port  64  are provided on the portion  54 . The first port  62  is in communication with the antechamber  46  of the base  12 , and a first vacuum source. The second port  64  is connected to a second vacuum source. The vacuum sources could be from a common vacuum generator and modulated, for instance, and need not be two separate sources. 
         [0070]    The first vacuum evacuates the antechamber  46  within the base  12  (referring back to detail of the first embodiment), and is further conveyed through port  62  into the nipple tunnel  56  between the sidewalls of the breastshield  52 . The first vacuum is applied to the breastshield  52  for a longitudinal force (axial) and for transporting the milk expressed from the nipple. Next, the second vacuum is applied from the second vacuum source, for radially pulling on the inner sidewall  55 . This in turn radially pulls upon (or expands/decompresses) the nipple, which is constrained and embraced by the inner sidewall  55 . Milk expressed into the downstream end  66  passes through the plurality of openings  58 , where it is conveyed through internal conduit structure to the bottle  22 . 
         [0071]    As can now be seen, when a vacuum source is applied to the port  64  to yield a pressure less than that of in the nipple tunnel  56 , the inner sidewall  55  expands, applying an outboard radial force to the encompassed nipple. When the vacuum levels near equilibrium, or the nipple tunnel goes more negative than the space  57 , the resilient inner sidewall returns to its rest state or even compresses. It will be noted that this embodiment could so be adapted to apply an inboard force by having the vacuum between the sidewalls be such that the vacuum at first port  62  is greater than that between the sidewalls, thus in essence yielding a more “positive” pressure being applied about the nipple. 
         [0072]    Here, again, the inner sidewall  55  substantially limits the amount of air in the system. 
         [0073]    Those of skill in the art will appreciate the embodiment illustrated in  FIG. 6  is not limited by the order the first vacuum source and the second vacuum source are applied to the breastshield  52 . In an alternative embodiment, the second vacuum source is applied to the breastshield  52  before the first vacuum source is applied to the breastshield  52 . In another embodiment, both the first vacuum source and the second vacuum source are simultaneously applied to the breastshield  52 . 
         [0074]      FIG. 7  is still another embodiment of a system for expressing breastmilk showing a system having a valve member capable of maintaining a baseline vacuum in the breastshield. As can be seen in  FIG. 7 , the breastshield  70  includes a receptacle portion  72 , an inner sidewall  74 , a tubular extension or nipple tunnel  76 , a valve  78 , an outer sidewall  80 , and a vacuum inlet  82 . 
         [0075]    In the breastshield  70 , the tubular extension  76  extends from the receptacle portion  72 . The valve  78  is provided at the downstream end of the tubular extension  76 , communicating with antechamber  46  of the base  12  (again, refer to the base and related structure of  FIGS. 1 and 5 ). The vacuum inlet  82  is between the antechamber  46  and the space  57  between the sidewalls. 
         [0076]    The inner sidewall  74  is, at its downstream end of the tubular extension  76 , sealed about the upstream end of the valve  78 , which here is a duckbill valve. As in the embodiment of  FIG. 6 , the inner sidewall  74  is pulled away from the nipple when a vacuum is applied between the sidewalls which is more negative (greater vacuum) than that in the nipple tunnel  76 . 
         [0077]    Of course, this is simply a function of pressure (or force) differential as between the tubular extension and the space  57 . Those with skill in the art will recognize many ways to generate the desired pressure or force differential for movement of the inner sidewall  74  besides what has been specifically described with respect to  FIGS. 6 and 7 . 
         [0078]    In operation, the inner sidewall  74 , which is preferably made of silicone rubber in a relatively thin thickness, receives the nipple of a breast and snugly holds the nipple and some adjacent breast in a supple embrace. 
         [0079]    Vacuum is applied from the vacuum source, which is preferably a pump, via the tube  20 , with the vacuum conveyed to the breastshield both at the antechamber  46  (downstream of the valve  78 ) and at the inlet  82 . While a common negative pressure is being applied both downstream of the valve  78  and at the inlet  82 , the valve  78  is designed to operate such that the vacuum in the space  57  between the sidewalls goes more negative than that in the nipple tunnel for a brief period. This applies the radial pull on the nipple, as the nipple tunnel  76  expands. Ultimately, the vacuum pressure causes the valve  78  to open, so milk passes through the valve  78 , and is transported to the milk container  22 . 
         [0080]    Various breastshields disclosed herein may be used with a vacuum pump as shown and described in a PCT application with attorney docket number F03507, entitled “Device and Method for Expressing Human Breastmilk,” filed on Sep. 17, 2010. Vacuum pumps for use in breastpumping are, however, well known. 
         [0081]    The valve  78  also can serve to yield a baseline vacuum being maintained in the nipple tunnel  76 , closing at a predetermined negative pressure, as previously described with relation to the first embodiment above. A baseline vacuum would be one that is maintained during some or all of a pumping session, such that the vacuum seen at the nipple does not return to ambient, but remains at, say, a pressure of approximately −20 to −50 mmHg, before returning to a greater vacuum during milk extraction. Those skilled in the art will appreciate the benefits of maintaining a baseline vacuum during operation. For example, milk expression should be more comfortable to the mother. 
         [0082]      FIGS. 8 through 10  show yet another embodiment of a system for expressing milk. The breastshield  84  is preferably molded in silicone, in large part, and is somewhat flexible. It has an outer wall  86 , an inner wall  87 , an upstream turned out rim  88  forming an opening, a downstream end  89 , and an inner sidewall  90 . A tubular extension or nipple tunnel  92  is thereby defined. A valve  94  is mounted on a dividing wall  91 , which extends transversely across the nipple tunnel, at a point where the nipple will preferably not impact the wall in any deleterious manner during pumping. The downstream end  89  connects to the antechamber  46  of the base  12 , for example (see  FIGS. 1 and 5  regarding the base  12  and related structure). 
         [0083]    Inboard of the sidewall structure  90  is a thin flexible member  95 , which extends across a quadrant of the upstream part of the nipple tunnel, in front of the wall. The thin flexible member  95  at its downstream end is sealed to the dividing wall  91 . This creates a bladder structure or member, which is preferably designed to be reminiscent of the tongue of a baby. There is a slot  93  in the wall  91  which communicates with the interior of the foregoing bladder. The slot  93  conveys vacuum pressure to the bladder interior. While a slot  93  is shown, it could be greatly expanded in this area, for ease in manufacturing. 
         [0084]    Reminiscent of the embodiment of  FIG. 7 , a negative pressure (vacuum) applied at the end  89  initially generates a pressure differential between the area of the nipple tunnel  92  within which the nipple is received and surrounded, and the interior of the bladder. This causes the member  95  to move radially outboard (or outward) relative to the nipple and the breast. This in turn pulls the nipple outwardly, and then contracts when the member  95  returns to its initial position. Responsive to this action, the nipple expresses milk. Milk expressed into the downstream end of the tubular extension  92  passes through the valve  94 , which is preferably a duckbill valve, where it is conveyed through internal conduit structure to the bottle  22 . Note that these types of breastshield shapes of  FIGS. 6-10  for instance, serve to best position the nipple therein, thereby further facilitating a minimization of any residual air volume. 
         [0085]    Turning now to  FIG. 11A , this is a modified version of the breastshield of  FIGS. 8 through 10 . This breastshield  96  has a member  95 ′ that radially extends farther into the tubular extension  92  than the member  95  of breastshield  84  of  FIG. 8 . Dividing wall  91 ′ is moved more downstream, with its duckbill valve  94 . 
         [0086]      FIG. 11B  is a variation of what has been described with respect to  FIG. 11A . Here, the bladder or tongue member  95 ″ is now separated from the sidewall structure  90 , and is much more like the forward part (free end) of a baby&#39;s tongue. What is particularly novel with this embodiment is that, when negative pressure (vacuum) is released downstream of the breastshield  96  (upon completion of the vacuum cycle), member  95 ″ actually initially expands within the extension  92  (given the pressure differential that then exists between the member and the interior of the extension  92 ). Note that the embodiment of  FIG. 11A  could also provide this feature. 
         [0087]      FIGS. 12 and 13  illustrate still another embodiment of a system for expressing milk. This time, the breastshield  98  assumes a relatively rigid more funnel-shaped construct, with a receptacle portion  100  having a more traditional circular cross section nipple tunnel  101  downstream thereof. There is an inner side wall  102  to the funnel, an upstream edge or rim  104  defining the widened opening for the portion  100 , and a downstream end  105 . 
         [0088]    Fitted inside of the funnel is a flexible liner  106 , which can be a sheath-like member previously described. Liner  106  has a rim  107  which is formed with an outer lip that is turned inwardly to form an annular channel around the circumference of the rim  107 . This channel is designed to more or less snap fit around the rim  104  of the conical portion, to fix the liner  106  at the upstream end. At the downstream end of the liner  106 , a knob  112  is formed. That knob  112  fits through an aperture of an endwall  109  that extends across the end  105  of the nipple tunnel, and is thereby held in place. The spacing between the rim  104  and the endwall attachment of the liner  106  is such that the liner  106  may be, or preferably is stretched, and pulled taut when attached within the funnel. The shape of the liner  106  is also funnel-like, but results in a space (plenum)  108  being formed between the inner sidewall  102  of the funnel and the outside of the liner  106 . Note that the downstream end  105  has a plurality of slots  111  for fluid conveyance (fluid being both milk and vacuum). The liner  106  includes one (or more) lateral openings  110  at the knob  112 , which operates much like the foregoing duckbill valves. 
         [0089]    In operation of the breastshield  98 , liner  106  is mounted inside of the funnel (portion  100  and nipple tunnel  101 ) so that sidewalls of the liner  106  are pulled away from the inner sidewall  102 . The nipple and breast placed in the liner  106  are thus closely embraced. The vacuum is applied from the vacuum source, which is preferably a pump, via the tube  20 , with the vacuum conveyed to the breastshield  98 . The vacuum causes the liner  106  to expand into the space between the inner sidewall  102 , in turn applying a radial outward force to the nipple. Milk expressed into the downstream end of the sheath-like member  106  passes through the lateral opening  110  where it is conveyed through the plurality of slots  111  of the endwall  109 , then through internal conduit structure to the bottle  22 . 
         [0090]      FIGS. 14 and 15A  show yet another embodiment of a system for expressing breastmilk. The system includes a breastshield  114  which is funnel-shaped, having a receptacle portion  116 , from which extends a somewhat tubular extension or nipple tunnel having a first part  124 . This nipple tunnel is formed as an extensible chamber, however, with another part indicated at  128 . The function of this extensible nipple tunnel will shortly be described. 
         [0091]    Located within the receptacle portion  116  and extending into the nipple tunnel is an inner liner part  126 . The inner liner part  126  is fixed at its upstream end to the inner wall of the receptacle portion. Its downstream end  132  extends inboard from the sidewall, and is spaced from the walls defining the tubular extension. Its downstream end  132  has a plurality of openings  138  for fluid flow. 
         [0092]    There is a duckbill valve  122  connected to the nipple tunnel. That valve communicates with conduit structure leading to a milk container, or could directly pass to the bottle. 
         [0093]    There is a hinge-like structure  130  formed as a bend between the two parts of the nipple tunnel  124 ,  128 . The distal end of the nipple tunnel is closed at  120 , with a knob formed thereon. With an axial force applied to the knob  120  to move it toward (direction  136 ) and then away from (direction  134 ) the distal end of the liner part  126  (thereby reciprocating part  128  of the nipple tunnel), the volume of the nipple tunnel  124 ,  128  is caused to contract and expand. This initially generates an intermittent vacuum (negative pressure) within the breastshield  114  (more so in the area around the nipple). 
         [0094]    The nipple is constrained in the liner part  126  within the nipple tunnel. Milk expressed by this reciprocating action flows through the openings  138 , into the nipple tunnel  124 ,  128  and then through the valve  122 .  FIG. 15A  illustrates the nipple tunnel being compressed in the direction  136 . After milk is expressed, it collects in the nipple tunnel  124 ,  128 . On the next stroke, the milk is pushed through the valve  122 , which is preferably a duckbill valve, where it is conveyed through internal conduit structure to the bottle  22 . 
         [0095]    Of further interest in this embodiment is that the milk thereby replaces the initial working fluid of the reciprocating pump formed by the expansible nipple tunnel, going from air to milk (liquid). The system thus goes from pneumatic system to a hydraulic system, increasing efficiency. Moreover, the mother&#39;s own milk can now be used to warm the breastshield  114 , which makes the mother more comfortable during milk expression, and research has demonstrated increases milk flow rate. 
         [0096]    In this embodiment, we now can see how the air or “dead volume” is virtually eliminated within the entire system.  FIG. 15B  is intended to further show this, illustrating how the valve  122  can be oriented upwardly (relative to ground), or in virtually any other position, since gravity is no longer the prime (or only) mover of the milk. Tubing or other conduit structure (not shown) would surround the valve  122 , for example, to convey milk to a container. Milkflow is thus effected by the pumping action of the reciprocating parts of the nipple tunnel  124 ,  128 , and is independent of gravity. This by itself is considered to be a highly significant advance in breastpumping. The entire breastpump assembly has furthermore become extremely compact and efficient. 
         [0097]      FIG. 15B  also illustrates the additional feature of applying a pressure sensor S to the system. This sensor would be used to monitor the pressure being applied at the nipple providing a signal to a controller via electrical connection  133 , for setting a desired maximum pressure for instance, or perhaps as well a desired minimum (referring back to the “baseline” pressure concepts discussed above). Use and application of such a pressure sensor or pressure transducer is disclosed in U.S. Publication No. 2008/0255503. 
         [0098]    The breastshield  114  disclosed in this embodiment would use a rotary drive mechanism  200 , such as in  FIG. 21 . The drive mechanism  200  has a ring  201  within which the breastshield  114  is maintained. Ring  201  has internal threads. Received within the ring  201  is a rotary drive member  202 , which is externally match-threaded to the ring  201 . A conventional motor  204  is schematically illustrated, and connects through a conventional drive train to the drive member  202  to thereby rotate the drive member  202 , relative to the ring  201 . The knob  120  of the breastshield  114  is mounted within an orifice of the drive member  202 . When the drive member  202  is turned in one direction, it moves outwardly relative to the ring  201 , thereby extending the nipple tunnel  124 ,  128 . When drive member  202  is rotated in the opposite direction, it moves inwardly relative to the ring  201 , compressing the nipple tunnel. 
         [0099]    Another example of a drive mechanism which may be used with the breastshield  114  and substantially eliminate “dead volume” throughout the entire system is shown in  FIG. 22 . This type of drive mechanism may include a piston lever arm system  300 , and is further described in U.S. Pat. No. 7,223,255, issued on May 29, 2007, entitled “System for a Portable Hands-Free Breast Pump and Method of Using the Same,” which is herein incorporated by reference in its entirety. The breastshield  114  would be adapted to fit the general makeup of the piston lever arm system  300 . The knob  120  of the breastshield  114  connects to a piston cylinder  306 . The piston lever arm system  300  includes a servomotor mechanism  302  connected to a lever arm  304 . The lever arm  304  is used to adjust the piston cylinder  306 . The servomotor mechanism  302  pivotally moves the lever arm  304 , which then linearly moves the piston cylinder  306  to move the knob  120 , in and out in a linear fashion, to thereby extend and compress the nipple tunnel  124 ,  128 . 
         [0100]      FIGS. 16 and 17  illustrate still another embodiment of a system for expressing breastmilk. The breastshield  140  includes an upstream cone  142 , a nipple tunnel  144 , and an inflatable chamber or bladder  146 . The cone  142  and nipple tunnel  144  yield a funnel-shape. 
         [0101]    As can be seen in  FIG. 16 , the inflatable chamber  146 , which is preferably toroidal, is coupled to the cone  142  and the nipple tunnel  144  at substantially the area of transition in the funnel to the nipple tunnel  144 . The nipple tunnel  144  is in communication with a vacuum source (not shown). The inflatable chamber  146  is in communication with a pressure source (not shown). 
         [0102]    In operation, the funnel receives the nipple  153  of a breast  150  and snugly holds the nipple  153  and some adjacent breast. In this embrace, the distal end of the nipple  153  extends into the nipple tunnel  144 . Next, as can be seen in  FIG. 17 , the inflatable chamber  146  expands and grows in size. The inflatable chamber  146  preferably expands in response to a pressure applied by the pressure source. When expanded, the inflatable chamber  146  contacts the breast. The inflatable chamber  146  preferably contacts the breast at substantially the area of transition from the areola to the nipple  153 . The nipple  153  further extends into the nipple tunnel  144  in response to the breast being contacted by the inflatable chamber  146 . 
         [0103]    Next, a vacuum is applied by the vacuum source, which the nipple tunnel conveys to the nipple  153 . The nipple surface area that the vacuum is conveyed to is minimized when the inflatable chamber  146  contacts the nipple (and any adjacent breast). In response to the vacuum action, the nipple  153  expresses milk. The milk flows through the nipple tunnel  144  and through a conduit structure to a container (not shown). Minimizing the breast area and surrounding open volume that the vacuum must interact with increases efficiency. 
         [0104]      FIGS. 18 and 19  show yet another embodiment of a system of expressing milk. The breastshield  154  includes a cone  156 , a nipple tunnel  158 , and a flexible membrane  161 . The flexible membrane  161  is preferably folded upon itself. A cup  160  has a sealing ring  164 , a distal or downstream end  166 , and an opening  168 . 
         [0105]    In the breastshield  154 , the cone  156  and nipple tunnel  158  define a funnel shape. The nipple cup  160  is in communication with a vacuum source (not shown). The flexible membrane  161  is located in the nipple tunnel  158 . Membrane  161  is connected to the nipple cup  160 , and is also connected to the nipple tunnel inner wall. Due to the connections of the stretchable membrane  161 , the stretchable member is configured to move in the nipple tunnel  158 . The sealing ring  164  is connected to the nipple cup  160 . The sealing ring  164  is located inside the nipple cup  160  upstream of both the distal end  166  and the opening  168 . The opening  168  is connected to an internal conduit structure, which is in turn is connected to a container (not shown), for milk flow. A one-way valve (not shown) may be placed at or beyond opening  168  to provide one-way air or milk flow through the tubing  175 . 
         [0106]    In operation, the funnel receives the nipple  173  of a breast  170  and snugly holds the nipple  173  and the adjacent breast. The nipple  173  extends into the area  162  within the nipple cup  160 . The nipple cup  160  can expand both laterally and radially to receive the nipple  173 . The nipple cup  160  expands to receive the nipple in response to the translation of the flexible, preferably stretchable, membrane  161  within the nipple tunnel  158 . Due to the translation of the membrane  161 , the nipple cup  160  is configured to receive nipples of varying diameter and varying length, thereby minimizing system volume. 
         [0107]    As can be seen in  FIG. 19 , the distal end of the nipple  173  extends past the sealing ring  164 . In this configuration, the flexible membrane  161  laterally seals the nipple  173 , which minimizes the nipple surface area to which a vacuum force is to be applied. 
         [0108]    Next, a vacuum may be applied by the vacuum source through a hose or tube  174 , and the vacuum is conveyed to the distal end  166  of the nipple cup  160 . In response to the vacuum, the nipple cup  160  applies a force to the nipple  173 . In response to the applied force, the nipple  173  expresses milk, and the milk flows through the opening  168  into tubing  175  and through the internal conduit structure to the container. 
         [0109]      FIG. 20  is still another embodiment of a system for expressing breastmilk. The breastshield  176  includes an upstream cone  178 , a downstream nipple tunnel  180 , nipple cover  182 , a collar  184 , and a cap  186 . The cap  186  includes an opening  188 . The cap  186  is much like that previously described with respect to the embodiment of  FIGS. 18 and 19 . 
         [0110]    In the breastshield  176 , the nipple cover  182  is attached at its upstream end to the cone  178 , and the nipple cover  182  extends into the nipple tunnel  180 . The collar  184  is located around the nipple at its base and functions much like an O-ring. The collar  184  is preferably connected to the inner wall of the nipple tunnel  180 . The cap  186  is connected at its upstream end to the nipple cover  182 . The opening  188  is located on the cap  186 , and the opening  188  is connected to tubing  198  and then to an internal conduit structure, which is in turn connected to a container (not shown), for milk flow. Alternatively, the milk outflow could go directly into a container. A one-way valve (not shown) may be placed at or beyond opening  188  to provide one-way air or milk flow through the tubing  198 . 
         [0111]    In operation, the funnel receives the nipple  194  of a breast  190  with the nipple  194  extending into the cap  186 . In this configuration, the nipple cover  182 , which is preferably a plastic film that is fluid permeable, or which has small openings in it, covers the nipple  194 , and the collar  184  closes the nipple cover  182  against the breast. The collar  184  preferably contacts the breast  190  at substantially the area of transition from the areola to the nipple  194 . When the vacuum source applies a vacuum through tube  196 , the vacuum generates a force applied to the nipple covered by the nipple cover  182 . In response to the applied force, the nipple  194  expresses milk. As can be seen in  FIG. 20 , the milk flows through the nipple cover  182  to the opening  188 . 
         [0112]    While certain features and embodiments of the present application have been described in detail herein, it is to be understood that the application encompasses all modifications and enhancements within the scope and spirit of the following claims.