Abstract:
Milk is extracted from a human breast by placing the breast in a cup having a vacuum port. The cup also has a flexible liner that allows vacuum to extract milk when the liner is in a first, open position, the milk being drawn into the vacuum port by the vacuum when the liner is in the first position. The liner also has a second position in which the nipple of the breast is compressed enough to substantially reduce the flow of milk from the breast. The liner is opened and closed in a pulsating manner at a predetermined pulsation rate. The user may select a pulsation ratio that produces acceptable milk transfer and comfort. Optimum pulsation ratios vary from user to user, but are generally between about  20 % and about  80 % for the vacuum portion of the pulsation cycle.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to apparatus for extracting milk from lactating women, and more particularly, to breast pumps that use pulsation within a range of pulsation ratios to enhance comfort and milk production.  
         BACKGROUND OF THE INVENTION  
         [0002]    Mechanical breast pumps for lactating women apply a vacuum to the breast, which draws milk from the nipple and collects the milk in a vessel such as a bottle. Most conventional breast pumps apply an oscillating vacuum to the breast from a single chamber in a breast cup, but Whittlestone U.S. Pat. No. 4,607,596 discloses a device with dual chambers that uses a liner in the breast cup and applies pulsation to the outside of the liner at regular intervals. This pulsation reduces congestion at the breast when the liner is closed, giving greater relief from the application of vacuum.  
           [0003]    While the Whittlestone patent suggests a pulsation rate of 40 pulsations per minute, it does not disclose a suitable pulsation ratio or time within a pulsation cycle during which the vacuum should be applied to the breast to accomplish milk production. The Whittlestone patent also does not recognize that optimum milk production is achieved at different pulsation ratios for different women, and even for one woman at different times.  
           [0004]    Accordingly, one object of this invention is to provide a new and improved apparatus for extracting milk from lactating women.  
           [0005]    Another object is providing new and improved breast pumps that use pulsation within a range of pulsation ratios to enhance comfort and milk production.  
           [0006]    Still another object is to provide new and improved breast pumps having a pulsation ratio that can be adjusted by the user.  
         SUMMARY OF THE INVENTION  
         [0007]    In keeping with one aspect of this invention, milk is extracted from a lactating human breast by placing the breast in a cup. A vacuum source is connected to the cup. The cup has a flexible liner that allows milk to be extracted when the liner is in the first, open position. The milk is drawn into the breast cup by the vacuum and conveyed into a collecting bottle when the liner is in the first position. The liner also has a second or closed position in which the nipple is compressed enough to substantially reduce the flow of milk from the breast. The liner is closed and opened in a pulsating manner at a predetermined pulsation rate that produces acceptable milk transfer and comfort. The relationship of time between the open and closed positions can be expressed as a ratio. Such a pulsation ratio may vary within and among users, but is between about 20% and about 80% open of the total of each pulsation cycle (i.e., time open/total time of entire cycle).  
           [0008]    In another aspect of the invention, the pulsation ratio is variable, and is adjustable by the user. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The above mentioned and other features of this invention and the manner of obtaining them will become more apparent, and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, in which:  
         [0010]    [0010]FIG. 1 is a side cross-sectional view of a milk collection assembly that can be used in the present invention;  
         [0011]    [0011]FIG. 2 is a top cross-sectional view of the milk collection assembly of FIG. 1, taken along lines  2 - 2  in FIG. 1;  
         [0012]    [0012]FIG. 3 is a cross-sectional view of the breast cup in the assembly of FIG. 1, shown with the liner partially collapsed by vacuum;  
         [0013]    [0013]FIG. 4 is an exploded view of the breast cup of FIG. 1;  
         [0014]    [0014]FIG. 5 is a block diagram of part of one embodiment of the present invention, using the milk collecting assembly of FIG. 1;  
         [0015]    [0015]FIG. 6 is a block diagram of a control system for use with the apparatus of FIG. 5; and  
         [0016]    [0016]FIG. 7 is a graph comparing the expected relationship between pulsation ratio and milk transfer, with the relationship obtained with the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0017]    As seen in FIGS. 1 and 2, a milk-collecting unit  10  includes a breast cup assembly  12 , a manifold assembly  14  and a milk collection unit  16 . The cup assembly  12  includes an opening  18  into which a lactating human breast may be inserted for extraction of milk.  
         [0018]    The cup assembly  12  also has a flexible liner  20  that extends within the cup assembly  12 . The liner  20  can be made of silicon or other suitable material. The inside  21  of the liner  20  forms part of an inner chamber  22  around the opening  18 , and the outside  23  of the liner  20  forms part of an outer chamber  24 .  
         [0019]    Manifold  14  includes a vacuum tube  26  and a pulse tube  28 , as seen in FIG. 2. The vacuum tube  26  passes vacuum into the manifold assembly  14 , the container  16  and the vacuum chamber  22  (FIG. 1). In use, the breast seals the opening  18  so that when the liner  20  is pressed against the breast at the opening  18 , milk is drawn into the container  16  by the vacuum, through the core of the liner  22  and an optional duck bill valve. When vacuum is applied to the outer chamber  24 , the liner  20  moves to the first, or open position in FIG. 1.  
         [0020]    A vacuum can be applied to the outer chamber  24 , or the outer chamber  24  can be raised to atmospheric pressure, although higher pressures could be used, if desired. When air is admitted through the pulsation tube  28 , atmospheric air fills the second chamber  24 , and the liner  20  closes in the manner shown in FIG. 3. The liner closes (second position) due to the differential pressures across the walls  21 ,  23  of the liner between the two chambers. The vacuum chamber  22  draws the liner  20  gently against the breast, and into contact with exposed milk channel openings (nipple sinuses), the contact, or compressive load substantially reducing milk flow from the nipple. Reducing the milk channel in this manner reduces vacuum exposure (hence, milk flow) to the breast and supports the breast in a gentle, compressive force mode. This compressive force tends to relieve congestion of blood, lymph, and other body fluids brought to the front portion of the breast tissue by the vacuum applied when the liner is in the first position.  
         [0021]    [0021]FIG. 4 is an exploded view of the cup assembly of FIG. 1. The cup assembly includes a case or housing  40  having a vacuum port  42  and a pulsed air port  44 . The pulsation tube  28  of FIG. 1 communicates with the port  42  in use. The liner  20  can wrap around over an insert  46  and the housing  40  on one end, and around the vacuum port  42  on the other end of the housing. Thus, the liner  20  and the housing  40  form the outer chamber  24  (FIG. 3) through which pulsed air and vacuum are alternately applied, and the liner  20  forms the chamber  22 , which is sealed by the breast.  
         [0022]    The vacuum and pulsed pressure in the airlines  26  and  28 , respectively, can be produced in various ways, including the manner shown in FIG. 5. A vacuum generator  50  produces vacuum in an optional reservoir  52 , preferably at about three to ten inches of mercury (Hg). The vacuum generator  50  could be a rotary vane pump, a scroll type pump, a piston-type pump, a Woble piston type pump, a diaphragm pump, a linear pump, a bellow, or other vacuum generator.  
         [0023]    Desired vacuum levels can be established with the assistance of vacuum regulators  54 ,  55  having mechanical or other adjustments  57 . A vacuum line  58  can be provided to operate the two breast cup assemblies  10  through the regulator  55  and the vacuum lines  26 . The vacuum is preferably modulated, but a constant vacuum is also suitable for extracting milk in accordance with the present invention. Modulation can be accomplished with a vacuum modulation/safety valve  59 , which can be a mechanical vacuum release valve, for example.  
         [0024]    An airline  60  provides vacuum to valves  62 ,  64 . The valves  62 ,  64  in turn, selectively provide alternating vacuum and atmospheric air to the pulsed airlines  28  in the breast cup assemblies  10 . A pressure differential of about 0.5 to 2.0 Hg is suitable to open and close the liner. The liner wall movement (pulsation) is produced using pulsator valves  62 , 64 , which use vacuum in the optional reservoir  52  to open the liner  20  and admit atmospheric air to close the liner, in conjunction with the vacuum present from the vacuum port  42 .  
         [0025]    Pulsator valves  62 ,  64  have two functions: first, they allow vacuum from the reservoir  52  (if used) into pulsation tubes  28 , which are linked to the breast cup; which opens the liner  20 ; second, they allow atmospheric pressure into these same lines (and the cups) to allow system vacuum to close the liner  20 . Valves made by BioChem Valve, Inc. in Oakland, Calif., Part No. 0075T3, S119, 12 vol., D.C., called a three-way solenoid valve having an “open,” “close” and “open to atmosphere” positions is one example of a suitable valve.  
         [0026]    The apparatus of claim  5  can be controlled by the control system shown in FIG. 6. The control system can include a CPU  70  or the like, programmed by instructions stored in a ROM  62  and loaded in a RAM  74 , if desired. Various operational parameters can be adjusted by the user as desired. For example, a pulsation ratio adjustment  76  can be provided, as well as a vacuum adjustment  78 . The pulsation ratio can be adjusted at several preset values between about 20% and about 80% (vacuum applied/total cycle time), and the pulsation rate can be adjusted at several present values between about  41  and  65  pulsation cycles per minute. The ratio and rate could also be continuously variable, if desired.  
         [0027]    Using the parameters set by the user, the CPU  70  controls the valves  62 ,  64 , through a de-multiplexer  80  and valve drivers  82 . The vacuum created by the generator  50  can be controlled through a driver  84 . Of course, other control systems could be used instead of this system.  
         [0028]    Each pulsation cycle applies vacuum to the breast for a portion of the cycle, and substantially cuts off the vacuum during the remaining portion of each cycle. The proportion of time the vacuum is applied divided by the total cycle time can be expressed as a percentage, as described in FIG. 7. Pulsation ratio is the comparison of time spent when the liner is moving towards and in the first position (open) versus the liner moving towards and in the second position (closed). While opening the liner longer would be expected to increase the rate of transfer of milk, the rate of transfer tends to decrease and the sensation of pain increases as the amount of time vacuum is applied is increased to 100%.  
         [0029]    The present inventors have discovered that while production initially increases, milk production actually decreases as the ratio approaches 100% vacuum. While milk production varies somewhat from individual to individual and from time to time, the present inventors believe that a pulsation ratio between about 20% and about 80% vacuum (vacuum exposure/total cycle time) will produce the best results using pulsation.  
         [0030]    The valve controller of FIG. 6 can be variable, if desired, so that the user can adjust the pulsation ratio and/or rate to obtain optimum milk transfer with the least amount of discomfort. To achieve a desired % or time open to vacuum in an open-close cycle, or pulsation cycle, the valve controller uses time control to open and close valves  62 ,  64  (FIG. 5). The valve controller can also control vacuum generation to produce pulsations or other varying increase and decrease of system vacuum, and thereby vary the inner chamber vacuum, if the vacuum reservoir  52  is not used. The inner chamber vacuum could also be modulated using proportional valves in the lines  26 , with appropriate control, in which case the reservoir can be used, if desired.  
         [0031]    The valve controller can be microprocessor driven, as described, or it can be a simple mechanical device. It is also contemplated that a stimulation cycle can be programmed to be used at the beginning of each milk expression session to increase sensitivity, blood flow and ultimately, milk production. The duration of the stimulation cycle along with the speed and vacuum levels can be user adjustable.  
         [0032]    The many advantages of this invention are now apparent. The pulsation ratio can be selected to optimize the milk transfer rate. Milk transfer can be optimized on an individual basis by allowing the user to select the pulsation ratio.  
         [0033]    While the principles of the invention have been described above in connection with a specific apparatus and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.  
         [0034]    U.S. patent application Ser. No. 09/876,891, filed Jun. 7, 2001, is hereby incorporated by reference.