Breast pump with functional vacuum pulse

Abstract

A method and system for enhancing milk expression from mammary alveoli includes providing a pump that delivers a pulsed vacuum. The pulsed vacuum may be delivered by a vacuum pump that employs a rigid piston, the pump being used as a multi-stroke accumulator pump. In one embodiment, a piston head of the rigid piston performs non-linear motion relative to the sidewalls of a cylinder of the pump, thereby generating oscillating pulses within a vacuum chamber in the cylinder. The vacuum pulse frequency of the pump is imposed on top of the cyclic vacuum frequency that would otherwise be imposed if the piston head merely moved up and down while maintaining a perpendicular relationship to the sidewalls of the cylinder.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This is a nonprovisional application and claims the benefit of the filing date of U.S. Provisional Application No. 62 / 815,135, filed on March 7, 2019, under 35 U.S.C. §119(e), the entire contents of which are incorporated herein by reference. Background Art Technical Field

[0003] The present disclosure relates generally to expressing milk and, more particularly, to a breast pump that generates and delivers a pulsed vacuum.

[0004] Description of the Prior Art

[0005] Mammary alveoli share many functional similarities with alveoli of the lungs. In the case of alveoli of the lungs, oxygen and carbon dioxide are transferred between the lungs and the bloodstream, with carbon dioxide being transferred to the air and then excreted from the body. In the case of mammary alveoli, components of breast milk, such as nutrients, are transferred from the bloodstream into breast milk and then excreted from the body. A known treatment for respiratory distress syndrome that occurs in term and near-term infants is the application of high-frequency oscillatory ventilation (HFOV). The effectiveness of this form of ventilation is attributed to the fact that HFOV improves oxygenation through the alveoli. The working principle of HFOV is the creation of vacuum pulses.

[0006] Conventional electric breast pumps provide a cyclic vacuum, whether the pump is a single-stroke or accumulator-type pump. While great strides have been made in providing breast pumps that apply forces to the nipple at frequencies that mimic those delivered by a feeding infant, the amount of milk expressed during expression using a conventional breast pump can be lower than the amount delivered via direct feeding. Furthermore, while the fat content of breast milk provides some of the greatest nutritional benefits of breastfeeding, the fat concentration in breast milk has been found to increase at the end of a feeding or expressing session. High fat concentration milk may be most desirable, as a higher fat concentration in milk would result in a more complete delivery of milk to a feeding infant, or in a more efficient breast pump. However, the physiology of the epithelial cells that secrete milk is such that they tend to close as the fat concentration in milk increases, thereby preventing delivery of high fat concentration milk to a feeding infant, or in the case of a breast pump, to a milk collection container. Summary of the invention

[0007] In view of the functional similarities between mammary alveoli and lung alveoli, we have designed a breast pump that utilizes vacuum pulse generation. By providing vacuum pulse generation in addition to (or in place of) conventional cyclic vacuum, the breast pump of the present disclosure provides improved milk removal from mammary alveoli and promotes maintenance of open pores of epithelial milk secreting cells to provide improved milk removal from mammary alveoli.

[0008] Advantageously, the breast pump of the present disclosure delivers a greater volume of collected breast milk during a single pumping session while applying a lower effective vacuum pressure to the breast.

[0009] In a preferred embodiment, the breast pump utilizes a multi-stroke accumulator with inherent vacuum steps. While conventional accumulator pumps utilize an elastic diaphragm, such pumps suffer from losses due to the damping effect of the diaphragm and its associated support structure on the vacuum pulses generated by the motor of such pumps. Rather than an elastic diaphragm, the present breast pump utilizes a solid piston head sealed in a cylinder. During use, the rigid piston generates a distinct vacuum step or pulse which can be transmitted through a vacuum delivery tube to a breast shield or related device, across a media separation membrane (if necessary), and ultimately to the suckling mother.

[0010] Although configured as a linear piston / cylinder breast pump, the system of the present disclosure exploits the characteristics of a multi-stroke pump, wherein the reciprocating members create small vacuum increments which accumulate together to achieve a target vacuum.

[0011] In order to transmit vacuum pulses with a solid piston, it has been found to be beneficial to actuate the solid piston in an eccentric manner. Due to the need to maintain the integrity of the pneumatic seal between the piston head circumference and the vacuum cylinder wall despite the eccentric motion of the solid piston, a low friction compression seal having a non-circular cross-sectional configuration, such as available from Precision Associates, Inc. of Minneapolis, Minnesota, USA, is used. Bi-directional lip seals are used at the interface between the piston head and the side wall of the vacuum cylinder.

[0012] The breast pump of the present disclosure applies different vacuum pulses to stimulate the milk alveoli. Compared with the traditional diaphragm accumulator breast pump running under similar power conditions, the present breast pump can achieve a higher vacuum because the energy loss caused by material stretching is eliminated. Because the rigid piston can empty more volume in the chamber for each individual stroke, the breast pump of the present disclosure can also be constructed to have a smaller total footprint than the diaphragm accumulator breast pump. Since the diaphragm breast pump is prone to fatigue and even diaphragm tearing, the rigid piston breast pump of the present invention has superior reliability. In addition, based on the strong correlation between the motor current consumption and the vacuum generated, vacuum control can be performed economically without expensive pressure monitors. The mechanical structure of the breast pump constructed according to the teachings of the present disclosure is also adjustable because the vacuum pulse frequency can be optimized by modifying the volume of the displacement chamber. The larger the chamber volume (which can be created by using a larger cylinder cross-section or by increasing the piston stroke), the larger the vacuum step, and the smaller the chamber volume, the lower the vacuum step. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a semi-schematic diagram of a conventional diaphragm accumulator pump actuated by an eccentric connection to a pump motor;

[0014] Figure 2 is a cross-sectional view of a multi-stroke accumulator linear piston / cylinder pump of the present disclosure having an eccentric connection between a rigid piston and a motor shaft;

[0015] Figure 3 is an exploded view of a rigid linear piston / cylinder and multi-directional seal assembly of a pump of the present disclosure;

[0016] Figure 4 is an exploded view of the rigid linear piston and eccentric roller bearing of the pump of the present disclosure with the motor and multi-directional seal;

[0017] Figure 5 is an end view of a bearing insert of a linear piston of a pump of the present disclosure, wherein an offset axis of the bearing insert is in a first position, coinciding with a bottom dead center position (or initial position) of the piston;

[0018] Figure 6 is an end view of a bearing insert of a linear piston of a pump of the present disclosure, wherein the offset axis of the bearing insert is in a second intermediate position, coinciding with an eccentric (or tilted) position of the piston;

[0019] Figure 7 is an end view of a bearing insert of a linear piston of a pump of the present disclosure, wherein the offset axis of the bearing insert is in a third position, coinciding with a top dead center (or chamber evacuated) position of the piston;

[0020] Figure 8 is a motor end view of a bearing insert of a linear piston of a pump of the present disclosure, showing the shaft receptacle of the bearing insert in a first position, and Figure 5 The first position of the offset axis of the bearing insert is coaxial and coincides with the bottom dead center position (or initial position) of the piston;

[0021] Fig. 9 is a motor end view of a bearing insert of a linear piston of a pump of the present disclosure, showing the shaft receptacle of the bearing insert in a second position, and Figure 6 The second position of the offset axis of the bearing insert is shown to be coaxial and coincident with the eccentric position of the piston;

[0022] Fig.10 is a motor end view of a bearing insert of a linear piston of a pump of the present disclosure, showing the shaft receptacle of the bearing insert in a third position, and Figure 7 The third position of the offset axis of the bearing insert is shown to be coaxial and coincident with the top dead center position of the piston;

[0023] Fig.11is an end view of a piston, bearing, bearing insert and multi-directional washer of a pump of the present disclosure, showing in solid lines the bearing insert in its first position and the piston in its corresponding bottom dead center position (or initial position), and showing in dashed lines the second and third positions of the bearing insert (and the respective eccentric and top dead center positions of the piston);

[0024] Fig.12 is similar to Fig.11 but showing in solid lines the bearing insert in its second position and the piston in its corresponding eccentric position, and showing in phantom lines the first and third positions of the bearing insert (and the corresponding bottom dead center (or initial) and top dead center positions of the piston, respectively);

[0025] Fig.13 is similar to Fig.11 and 12 but showing in solid lines the bearing insert in its third position and the piston in its corresponding top dead center position, and showing in phantom lines the first and second positions of the bearing insert (and the respective bottom dead center (or home) and eccentric positions of the piston);

[0026] Fig.14 is an end view of a piston-cylinder assembly of the present disclosure, with the cylinder in phantom, the bearing insert in its second position, and the piston in its corresponding eccentric position;

[0027] Fig.15 is a schematic diagram of an exemplary cycle of a pump of the present disclosure;

[0028] Fig.16 is a perspective view of a motor and piston-cylinder assembly of a pump of the present disclosure;

[0029] Fig.17 is along Fig.16 A cross-sectional view of the piston-cylinder assembly of the pump of the present disclosure taken along line 17-17 with the bearing insert in its second position and the piston in its corresponding eccentric position;

[0030] Fig.18 is a perspective view of a pump of the present disclosure;

[0031] Fig.19 is another perspective view of the pump of the present disclosure with the housing of the motor removed;

[0032] Fig. 20 is an exploded view of the motor and piston-cylinder assembly of the pump of the present disclosure;

[0033] Fig.21 is a perspective view of a pump of the present disclosure, including a motor housing;

[0034] Fig. 22 is a graph of vacuum pressure versus time (in mmHg / second) comparing vacuum output from a conventional single-stroke pump, a conventional diaphragm pump, and a multi-stroke accumulator pump of the present disclosure;

[0035] FIG23 is a graph of milk flow rate (in grams per second) versus time (in minutes) during an expression session using a conventional accumulator breast pump (designated "18202QUEEN" in FIG23) having four displacement chambers in various emptying states; and

[0036] Fig.24 is a graph of milk flow rate (in grams per second) versus time (in minutes) during an expression session using a breast pump having a multi-stroke accumulator linear piston / cylinder pump of the present disclosure. DETAILED DESCRIPTION

[0037] Referring to FIG. 1 , a conventional diaphragm accumulator pump 10 is shown. The piston 12 of the diaphragm accumulator pump 10 is eccentrically engaged with an actuator motor (schematically indicated by reference letter M in FIG. 1 ) along a shaft 14. With each rotation of the shaft 14, the piston 12 first applies an upward stroke and then a downward stroke to the diaphragm 16. While this cyclic motion has the desired effect of building up pressure in the vacuum chamber 18, there is a loss of pressure across the membrane 16 during each stroke.

[0038] The accumulator pump 100 of the present disclosure is Figure 2 1 and 104. The solid piston head 102 is shown in cross section and has a solid piston head 102 located within a cylinder 104. The solid piston head 102 is actuated in an eccentric manner to transmit vacuum pulses to a surface, such as a breast or nipple, to which vacuum pressure from the pulses is applied. The vacuum pressure can be applied directly, or to an intermediate surface, such as a media separation membrane (not shown), for maintaining the integrity and sterility of the pump components and avoiding contamination of the collected fluid (e.g., breast milk).

[0039] The solid piston head 102 engages the side wall 106 of the cylinder 104. Because the solid piston head 102 is actuated in an eccentric manner, the piston head 102 does not maintain a perpendicular relationship with respect to the side wall 106 throughout its travel along the interior of the cylinder 104. Instead, the disc-shaped piston head 102 oscillates in an inclined manner (e.g., Figure 2 In order to maintain the sealing engagement of the piston head 102 with the side wall 106 of the cylinder 104 throughout the eccentric actuation of the piston head 102, a multi-directional, low friction compression sealing gasket 108 having a non-circular cross-sectional configuration is preferably used, such as is available from Precision Associates, Inc., Minneapolis, Minnesota, USA. Bidirectional lip seals.

[0040] In certain embodiments, eccentric actuation of the solid piston head 102 can be achieved using a rotatable bearing 110 that receives a bearing insert 112 having an offset rotation axis 114. The rotatable bearing 110 and the bearing insert 112 are received in complementary circular openings 116 of the piston head 102. The motor M of the pump 100 includes a motor shaft MS that is securely received in a shaft receptacle 118 of the bearing insert 112 that is coaxial with the offset rotation axis 114 of the bearing insert 112.

[0041] The actuation sequence of the multi-stroke accumulator linear piston / cylinder pump disclosed in the present invention can be referred to Figure 5-17 The three different positions of the bearing insert 112 are respectively Figure 5 , 6 and 7 (end view) and Figure 8 , 9 and 10 (motor end view). The corresponding views of the piston head 102 and the sealing gasket 108 are shown in Fig.11 , 12 and 13. Figure 5 , 8 11 shows the bearing insert 112 in a first position, corresponding to an initial position or bottom dead center position of the piston head 102 . Figure 6 , 9 12 show the bearing insert 112 in a second position, corresponding to an eccentric position of the piston head 102 . Figure 7 , 10 13 shows the bearing insert 112 in a third position, corresponding to the top dead center position of the piston head 102. Although the piston head 102 and the sealing gasket 108 are in Fig.11 , 12 1 and 13 are shown in solid lines in each of the respective first, second and third positions, respectively, but the alternating positions of the piston head 102 are shown in dashed lines in each of these figures.

[0042] refer to Fig.12 , 1417, it will be appreciated that when the piston head 102 is in the eccentric position, the piston head 102 not only moves vertically, but also moves at an angle relative to the side wall 106 of the cylinder 104. Compared to a conventional single-stroke piston, the pump 100 of the present disclosure advantageously applies a vacuum pulse frequency that exceeds the cyclic vacuum frequency that would otherwise be applied if the piston head 102 only moves up and down once. The vacuum pulses are attributable to the multiple rotations (approximately 20 revolutions) of the piston head 102 relative to the side wall 106 of the cylinder 104 during the cyclic vacuum cycle. Two check valves allow the vacuum to increase with each rotation until the target vacuum is reached. The volume of air moved during a single rotation of the piston is approximately 1 / 20 of the volume of air displaced by a conventional single-stroke piston.

[0043] An exemplary cycle of the pump of the present disclosure is Fig.15 The following table shows the state of each component in the loop at a given loop state:

[0044] refer to state piston import exit Solenoid valve 1 Top Dead Center (TDC) 0 1 0 0 2 Air Intake 1 1 0 0 3 Bottom Dead Center (BDC) 0 1 0 0 4 exhaust 1 0 1 0 5 End the loop 1 0 1 1

[0045] like Fig.21 As shown, the pump includes a port P that can be placed in fluid communication with a tubing system (shown in dotted lines in the figure), the tubing system includes a first length of tubing T1, a connector J, a second length of tubing T2, which is in fluid communication with a first breast milk collection kit K, the kit including a breast milk collection container C for receiving a breast (not shown) and a media separation membrane (also not shown) and an interface I, such as a breast shield, to allow vacuum to be applied to the interior of the interface, and thus to the breast received therein, and to allow breast milk to be collected while isolating the tubing circuit from the breast milk, thereby preventing contamination of the pump. To provide simultaneous pumping, the system can optionally further include a third length of tubing T3 in fluid communication with a second breast milk collection kit (not shown).

[0046] Other embodiments within the scope of the present disclosure include alternative structural configurations of the vacuum pump mechanism for achieving controllable vibration pulses. For example, rather than having a piston that moves eccentrically, the vacuum pump has a piston that remains vertically oriented throughout its travel along the sidewall 106 of the cylinder 104, but employs a yoke, connecting rod, and / or direct action (e.g., a solenoid, servo motor, or a DC stepper motor capable of pulse drive).

[0047] Fig. 22A graphical comparison is made of vacuum-time graphs for a conventional single-stroke pump 200 (which, as can be seen, produces a cyclic vacuum reflected by a smooth vacuum curve), a conventional diaphragm accumulator pump 10, and a multi-stroke accumulator pump 100 of the present disclosure. Although the diaphragm accumulator pump 10 can apply a non-smooth vacuum curve, the magnitude of the vacuum pressure changes is small, which may be due to the damping effect of the diaphragm 16. In addition, as the diaphragm 16 degrades over time, such as due to fatigue, rupture, or tearing of the diaphragm 16, the vacuum curve of the diaphragm accumulator pump 10 tends to smooth out over time. The ability to repeatedly obtain predictable vacuum pressure changes using the diaphragm accumulator pump 10 also lacks precision and presents fundamental difficulties. The multi-stroke accumulator pump 100, due to the eccentric motion of its rigid piston head 102 and the absence of a diaphragm 16, is able to reliably tune to a predictable vacuum frequency.

[0048] The motor M of the multi-stroke accumulator pump 100 of the present disclosure has increased torque relative to the motor used with a conventional single-stroke pump 200 or diaphragm accumulator pump 10, which is necessary to achieve discernible, predictable vacuum pulses of sufficient magnitude to obtain advantageous results, as described in more detail below. The benefit of the increased torque of the motor M is that each vacuum pulse produces a different load on the motor shaft MS that is proportional to the current draw of the motor M. Therefore, the vacuum load can be accurately predicted based on the current draw.

[0049] Another benefit of the correlation between the current consumption of the motor M and the resulting vacuum of the multi-stroke accumulator pump 100 of the present disclosure is that the pump 100 can be controlled by monitoring the current output of the motor M without including a pressure monitor. To avoid applying too strong a vacuum, a predetermined, not-exceeded current output of the motor M can be set.

[0050] The net effect of the predictable vacuum pulses generated by the multi-stroke accumulator pump 100 of the present disclosure when used in a breast pump is increased oxygenation of the mammary alveoli and improved milk letdown, compared to the vacuum provided by a conventional single-stroke pump 200 or diaphragm accumulator pump 10. The combined cyclic vacuum frequency and vacuum pulse frequency applied by the multi-stroke accumulator pump 100 impart high frequency oscillatory ventilation to the mammary alveoli. In a manner similar to the treatment of respiratory distress syndrome by the application of HVOCs, which utilizes vacuum pulse generation to provide greater oxygenation to the alveoli, it has been found that increased stimulation of the mammary alveoli during breast pumping results in an increased amount of breast milk collected.

[0051] The percentage of available milk removed, or PAMR, is a metric used to quantify the amount of breast milk collected.

[0052] 23 and 24 illustrate a comparison diagram of the multi-stroke accumulator pump 100 ( Fig.24) during a pumping session compared to the same nursing mother's milk flow rate during a pumping session using a conventional accumulator breast pump ( FIG. 23 ).

[0053] In addition, it is understood that breast milk with a higher fat concentration can more completely deliver milk to a feeding baby and the pump is more effective. During the pumping process, it was found that the viscosity of breast milk increased near the end of the pumping process, indicating that the fat content in the breast milk increased. However, using a conventional circulating vacuum breast pump, although the epithelial lactocytes produce additional desired high-nutrition, relatively high-fat breast milk, the poorly ventilated alveoli tend to close, or the viscosity of the breast milk hinders further secretion of breast milk through the alveoli. This precious extra breast milk, when not released through the alveoli, will not be used. Over time, whether through infant feeding, sucking or some combination of the two, the inability to drain all available milk from the alveoli will reduce the available milk supply. Therefore, the advantage of the multi-stroke accumulator pump 100 of the present disclosure and other vacuum pump mechanisms that implement controllable vibration pulses within the scope of the present disclosure is that a device that helps to completely or nearly completely empty the alveoli is provided, which promotes an increase or at least continuous milk supply over time. By using the multi-stroke accumulator pump 100 of the present disclosure, it has been discovered that not only is increased milk collection achieved during a given pumping cycle, but that the collected milk includes higher fat content milk that has heretofore not been collected by electric and manual breast pumps.

[0054] Yet another benefit of the disclosed multi-stroke accumulator pump 100 and other vacuum pump mechanisms that implement controllable oscillating pulses within the scope of the disclosure is the increase in milk flow rate during pumping achieved by applying less vacuum pressure. Practical benefits of being able to achieve increased milk collection at lower vacuum pressures include lower power requirements (which facilitates the use of less expensive power sources, lighter power sources, and / or rechargeable power sources that require less time to charge or maintain their charge longer before needing to be recharged), and greater comfort for the nursing mother. Increased pumping efficiency also provides benefits such as faster pumping (and therefore shorter pumping times), more breast milk collected during a single pumping session, and, as described above, an increase or at least a lesser decrease in breast milk supply over time.

[0055] Although the present disclosure has human milking as its primary use, milking machines for the dairy industry can be constructed with pump mechanisms utilizing multi-stroke accumulator pumps manufactured according to the teachings of the present disclosure and other vacuum pump mechanisms that achieve controllable vibration pulses to achieve many (if not all) of the benefits described herein. For example, for milking machines for the dairy industry, the interface I can instead be an interface that receives one or more cow teats. A single pump of the present disclosure can be used in such devices that are pneumatically connected to more than two teats and even to more than a single lactating cow at the same time, so as to milk multiple cows at the same time.

[0056] The multi-stroke accumulator pump 100 may operate at 0.1 mmHg or higher and at a frequency below 80 Hz. The frequency may be below 30 Hz, or in the range of 10-30 Hz.

[0057] Although certain embodiments are described herein, changes may be made which remain within the scope of the appended claims.

Claims

1. A non-therapeutic method of pumping breast milk, comprising: providing an interface in which a breast or nipple can be received for expressing milk; providing a vacuum source in communication with the interface, the vacuum source comprising an accumulator pump having a solid piston head located in a cylinder and engaging a side wall of the cylinder, whereby the solid piston head is actuated in an eccentric manner such that the solid piston head does not maintain a perpendicular relationship with the side wall of the cylinder during its travel within the cylinder; and The vacuum source is operated to apply a cyclic vacuum and a vacuum pulse frequency, wherein the vacuum pulse frequency is applied over the cyclic vacuum frequency to produce a combined vacuum.

2. The non-therapeutic method of claim 1, wherein when operating the vacuum source, the combined vacuum has a frequency below 30 Hz.

3. The non-therapeutic method of claim 1, wherein when operating the vacuum source, the combined vacuum has a frequency in the range of 10-30 Hz.

4. The non-therapeutic method of claim 1, wherein the combined vacuum is generated having a net effective vacuum of at least 0.1 mmHg and a frequency below 80 Hz.

5. A pumping non-therapeutic method, comprising: providing a pump which applies vacuum pulses in addition to the cyclic vacuum, the cyclic vacuum and vacuum pulses combining to provide a vacuum of varying amplitude, The pump is an accumulator pump having a solid piston head located in a cylinder and engaged with the side wall of the cylinder, whereby the solid piston head is actuated in an eccentric manner so that the solid piston head does not maintain a perpendicular relationship with the side wall of the cylinder during its travel within the cylinder.

6. A breast pump, comprising: a vacuum source for applying a cyclic vacuum, the vacuum source comprising an accumulator pump having a solid piston head located in a cylinder and engaging a side wall of the cylinder, Wherein the solid piston head is actuatable such that the solid piston head does not maintain a perpendicular relationship with a side wall of the cylinder during its travel within the cylinder and such that the vacuum source also applies a vacuum pulse frequency.

7. The breast pump according to claim 6, further comprising: a drive motor having a motor shaft; The solid piston head is eccentrically mounted on the motor shaft and is actuatable by rotation of the motor shaft to translate vertically along the axis of the cylinder and at an angle offset from the axis of the cylinder; One or more valves are provided on the wall of the cylinder, the one or more valves allowing the application of negative pressure accumulated in the cylinder after a number of cycles of the solid piston head in the cylinder.

8. A breast pump according to claim 7, wherein each vacuum pulse produces a different load on the motor shaft which is proportional to the current draw of the motor.

9. A breast pump according to claim 8, further comprising a sensor that senses the effect of the load applied to the motor shaft by each vacuum pulse on the current draw of the motor, and a controller that includes a memory and a comparator, the memory being stored on a non-transitory computer readable medium and including a target vacuum pressure, the comparator comparing the effect on the current draw of the motor sensed from the sensor with a stored target vacuum pressure, and selectively opening or closing the one or more valves based on whether the comparator determines that the effect on the current draw of the motor is above, below or equal to the target vacuum pressure.

10. A breast pump according to claim 7, further in combination with at least one breast shield and a conduit in pneumatic communication with the breast shield and one or more valves of the cylinder.

11. A breast pump according to claim 7 in combination with one or more additional breast pumps.

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