Abstract:
A breast pump comprises a breast cup and a source of positive and vacuum to the breast cup. The pressure and vacuum are set to an initial value for a fixed period of time, and they are not adjusted by a user. The initial values are selected to allow the breast cup to be repositioned by a user before higher levels of pressure and vacuum are applied.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 11/300,531, filed Dec. 14, 2005, which claims priority to U.S. Provisional Patent Application No. 60/637,709, filed Dec. 21, 2004, the disclosure of each of these applications is incorporated herein by reference thereto. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is generally related to breast pumps for extracting milk from the breasts of human females. More particularly, the present invention is related to such a pump that is designed to massage the breast in order to promote the flow of milk. 
       BACKGROUND OF THE INVENTION 
       [0003]    For various reasons, a lactating woman may wish to extract and collect her milk, and pumps designed for that purpose are well known. Such a pump typically comprises a cup or funnel that fits over the breast and a neck into which the nipple fits. The other end of the neck is connected to an intake of the actual pumping mechanism, which may be electric or hand operated. 
         [0004]    However, the human breast is adapted to respond optimally to suckling by a human baby, whose lips tend to move rhythmically as the baby suckles, massaging the breast. This massaging action stimulates the discharge of milk Merely attempting to suck milk from the nipple is much less effective, because the breast does not respond well. 
         [0005]    In the commercial milking of cattle, it has for many years been normal practice for the teat cups of a milking machine to have flexible liners. By cyclically changing the pressure in the space outside the liner, the milking machine massages the teats, encouraging the flow of milk. 
         [0006]    U.S. Pat. No. 6,273,868 and U.S. Pat. App. No. 2003/0153869, which are incorporated herein by reference in their entirety, describe breast cups and pumps for human females in which the breast is massaged by supplying a cyclically varying suction and pressure to the nipple tube and to flexible chambers in the breast cup. The supply of pressure to concentric rings of chambers is coordinated to produce a desired pattern of stimulus. 
       SUMMARY OF THE INVENTION 
       [0007]    One embodiment of the invention provides a breast pump, comprising a breast cup, a source of pressure to the breast cup, and a source of vacuum to the breast cup, wherein the pressure and the vacuum are set to a first pressure and a first vacuum for a set period of time, and both are not changeable by a user during the set period of time. 
         [0008]    A further embodiment of the invention provides a method of operating a breast pump comprising applying a first pressure and a first vacuum to a breast cup for a set period of time, wherein the first pressure and the first vacuum are not changeable by a user during the set period of time, and operating the breast pump at an operating pressure and an operating vacuum after the set period of time has elapsed. 
         [0009]    After the increase to a working value, the breast pump may operate at a steady value of positive and/or negative pressure that is adjustable in use, for example, is selected by a control operable by the user. In this case, the pressure may increase from the starting value to a fixed first working value, and then ramp from the first working value to the steady value selected by the user. The fixed first working value may then be within the range of values that can be selected for the steady value. 
         [0010]    In the case of a breast pump in which positive and/or negative pressure is applied to the breast to stimulate it, and negative pressure is applied to the nipple to suck out milk, both pressures may increase from a starting value to a working value. The increases may take place over the same period of time. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    For the purpose of illustrating the invention, there are shown in the drawings forms of the invention which are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown. 
           [0012]      FIG. 1  is a block diagram of one embodiment of a breast pump according to the invention. 
           [0013]      FIG. 2  is a flow chart of the operation of one embodiment of a breast pump according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to the accompanying drawings, where like numerals identify like elements, and initially to  FIG. 1 , one form of breast pump constructed in accordance with an embodiment of the invention, indicated generally by the reference number  20 , comprises a breast cup  22 , a pump  24 , and a pump controller  26 . 
         [0015]    The breast cup  22  may be similar to those shown in U.S. Pat. No. 6,273,868 and U.S. Pat. App. No. 2003/0153869, in which a first air line  28  supplies negative pressure to a nipple tube  30  of the breast cup  22  in order to suck milk from the nipple into a collecting bottle  32 , and at least one second air line  34  supplies air at positive and/or negative pressure to flexible chambers  36  in a conical part of the breast cup  22 . In this specification, pressures are described as positive or negative relative to ambient pressure, and are measured from ambient pressure as zero gauge. The chambers  36  may be formed of an elastomeric or other resilient material, so that they can be distorted from a relaxed configuration, and return to the relaxed configuration when the distorting force is removed. 
         [0016]    The pump  24  comprises a diaphragm pump  38  and a pump motor  40  that is controllable to vary the pressure, positive and negative, produced by the diaphragm pump  38 . In the breast pump  20  shown in  FIG. 1 , the pressures in the first and second air lines  28  and  34  are produced by a single diaphragm pump  38  driven by a single motor  40 . Changes in the output of the diaphragm pump  38  therefore affect the pressures in the lines  28  and  34  proportionately and synchronously. 
         [0017]    Depending on the design of the flexible chambers  36 , they may be supplied alternately with positive pressure to expand them and negative pressure to contract them. Alternatively, the chambers  36  may be supplied with pressure, for example, positive pressure, intermittently to distort them, and may be restored to a relaxed configuration by the resilience of the material of the chambers  36  when the applied pressure is removed. The applied pressure may be removed by allowing air to flow to or from the surrounding atmosphere through a bleed port. The bleed port may be continuously open, with the diaphragm pump  38  achieving the desired pressure by pumping air within the system faster than it flows through the bleed port. 
         [0018]    The pump controller  26  controls the pump motor  40  in accordance with inputs from a control panel  42 , which may include an on/off switch  44  and a control  46  to raise and lower at least one pressure level. Other controls  48  to adjust other settings of the pump may also be provided. The control panel  42  may also contain a display  50  with indicators to show the progress of the sequence of steps described below. The controls  46 ,  48  may be controls such as rotary knobs that show directly the positions to which they are set. Alternatively, the display  50  may also contain indicators to show the levels set by the controls  46  and  48 . 
         [0019]    Referring now to  FIG. 2 , in one embodiment of the breast pump  20 , when the pump is initially started and initialized, in step  102  it operates at a factory-set starting pressure. The starting pressure may be too low (that is to say, too close to zero gauge) to be effective in stimulating the release of milk in a typical user, and may be a pressure of approximately zero gauge, that is to say, with the pressure in the lines  28  and  34  substantially the same as the pressure outside. 
         [0020]    In steps  104 ,  106  and  108 , the pump operates, while gradually changing the pressure supplied to the line  28  and/or the line  34  in a “ramp” from the starting value to a first working value. If the pressure is starting at or near to zero gauge, the change will be an increase in a positive pressure and/or an increase in the gauge level of a negative pressure. In one embodiment, the most significant factor is the peak pressure during the pump cycle, and a satisfactory ramp can be generated by incrementing the peak pressure for each successive cycle. In this embodiment, in step  104  the pump cycles, in step  106  the controller  26  checks whether the ramp from the starting pressure of step  102  to the first working value is completed, and if the ramp is not completed, in step  108  the pump controller  26  increases the pressure supplied for the next cycle of the pump. If positive and negative pressure are generated on alternate half cycles of the diaphragm pump  38 , then the pump controller  26  may repeat steps  104 ,  106  and  108  for every half cycle. Those skilled in the art will understand how to adapt this process to other types of pump and to other desired ramp profiles. 
         [0021]    In step  106 , the pump controller  26  may monitor the progress of the pressure change in various ways, for example, by measuring the output pressure in line  28  or line  34 , or by counting the number of cycles, or by measuring the time that has elapsed. If the cycle time and the size of the pressure increment are both known, these measures may be substantially equivalent. Those skilled in the art will understand how to monitor the progress of the pressure increase in other ways, or when the cycle time and/or pressure increment is not uniform. In one embodiment, the pump  24  may produce a cycle of pressure every 2 seconds, and the pressure increase may be an increase at a substantially uniform rate over period of about 25 seconds. The ramp from the starting value to the first working value then consists of about 12 steps. 
         [0022]    When the pressure has reached the first working value, in steps  110  and  112  the pump controller  26  causes the pump  24  to continue working at that value for a period of, for example, 20 seconds. 
         [0023]    In step  114  the pump controller  26  gets from the control panel  42  the pump pressure that the user has set with the control  46 . In step  116  the pump controller calculates a ramp from the first working value to the pressure set by the user. In the interests of clarity, steps  114  and  116  are shown in  FIG. 2  after the loop at steps  110  and  112 . However, steps  114  and  116  may be performed while waiting for the loop to time out at step  112 . Alternatively, step  114 , and optionally also step  116 , could be carried out at an earlier stage. The display  50  may indicate to the user the progress of the breast pump  20  through the process steps shown in  FIG. 2 . In particular, if the time for which the pump controller  26  dwells at the first working value in steps  110  and  112  is as long as 20 seconds, it may be desirable to indicate this dwell clearly to the user, so the user does not become concerned that the breast pump is not responding to the setting of the pressure control  46 . 
         [0024]    In steps  118 ,  120  and  122 , the pump controller  26  ramps the pressure from the first working value to the value set by the user. Steps  118 ,  120  and  122  may use a procedure similar to the procedure used in steps  104 ,  106  and  108 . The first working value may be set near the middle of the range of pressures available to, or typically chosen by, users of the breast pump  20 , so the ramp may be a further increase in the pressure or a decrease in the pressure. The ramp may take, for example, 5 seconds. If the pump  24  continues to operate on a 2-second cycle, the ramp then consists of 2 or 3 iterations of step  122 . However, most users in practice select pressure values near to the middle of the range, so the pressure change at step  122  is not usually much larger than the change at step  108 . 
         [0025]    The gradual change of pressure enables the user of the breast pump to adjust the position of the breast cup  22  to the most effective and/or most comfortable position before the breast pump  20  reaches its working level. If the full working pressure were applied at startup, and the breast cup  22  were not correctly positioned, the user could experience some discomfort. With the breast pump  20  operating in accordance with  FIG. 2 , however, because the pressure level ramps up gradually, any misalignment of the breast cup  22  becomes noticeable, and can be corrected, before it becomes uncomfortable. 
         [0026]    Then, in step  124 , the pump continues to cycle at a steady value at the pressure set by the user. In step  126 , the pump controller may check from time to time whether the user has used the control panel  42  to enter new settings. If so, the new settings are evaluated in step  128 . If the new setting is a command to stop the pump, then the pump stops. If the new setting is a change in pressure, then in step  130  the pump controller  26  updates the pump cycle and returns to step  124  to continue pumping at the new pressure. If the new setting is a large change in pressure, the pump controller  26  may go from step  130  to step  122 , and use a ramp to change the pressure gradually from the previous setting to the new setting. 
         [0027]    If the pump continues to operate, then in step  132  the pump controller  26  may stop the pump after a predetermined time period, for example, one hour. 
         [0028]    As an example of pressures used in the breast pump  20 , when working in its steady state the pressure may be adjustable by the control  46  between a minimum of zero gauge pressure and a maximum of 240 mm Hg negative gauge pressure in line  28  and 190 mm Hg positive gauge pressure in the line  34 . The first working pressure at step  110  may be set between 50 and 150 mm Hg negative gauge pressure in line  28  and between 50 and 110 mm Hg positive gauge pressure in the line  34 . The pressures are taken at the peak of the cycle. The minimum of the cycle is substantially zero gauge pressure, produced by allowing the applied pressure to vent to atmosphere. It will be understood that the desired pressure in the line  34  depends on the design of the breast cup  22 , and especially on the design of the chambers  36 , because the effect of a particular pressure will depend on the size and shape of the chambers, and on how strong a resilient restoring force opposes the pressure. 
         [0029]    The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention. For example, the pump controller  26  could carry out steps  114  and  116  as part of the initialization procedure in step  102 , and then ramp the pressure directly from the starting value to the value set by the user. 
         [0030]    If the pressure is ramped in two stages from the starting value to a first working value and then to the steady value set by the user, the pause at the first working value in steps  110  and  112  is not necessary. However, this pause is useful to allow time for steps  114  and  116 , and avoids an abrupt transition if the ramps before and after the pause are in opposite directions. 
         [0031]    Although ramps having a constant rate of change of pressure over time are simple to implement, those skilled in the art will understand how to adapt the embodiment described to produce a varying rate of change of pressure if desired, for example, to blend more smoothly into the steady pressure of steps  110  and  124 . 
         [0032]    Although a fixed time for the ramp in steps  118 ,  120  and  122  has been described, the ramp could be, for example, a fixed rate of change, with the time taken depending on the amount of the change, or some compromise between constant time and constant rate. 
         [0033]    Although a pump  24  with a fixed cycle time has been described, the pump could have a user-selected cycle time set by the control  48 . In that case, the user-selected cycle time could be applied from the beginning, or it could be obtained at step  114  and applied during the ramp loop of steps  118 ,  120  and  122 . 
         [0034]    Although the breast pump  20  has been shown in  FIG. 1  with a single breast cup  22 , it may alternatively be provided with two breast cups  22 , for simultaneous extraction of milk from both breasts of a human female. Positive and negative pressure may be supplied to both breast cups by T connectors in the lines  28  and  34 . The breast pump  20  may be designed to operate with either a single breast cup or two breast cups. The maximum pressure available may then be lower when two breast cups are used than when a single breast cup is used. 
         [0035]    Other variations are contemplated and will be understood by those in the art.