WO2000006988A2

WO2000006988A2 - Slow fluid flow regulator

Info

Publication number: WO2000006988A2
Application number: PCT/IL1999/000407
Authority: WO
Inventors: Ofer Barnea
Original assignee: Roni-Pal Ltd.
Priority date: 1998-07-27
Filing date: 1999-07-26
Publication date: 2000-02-10
Also published as: AU4927799A; IL125528A0; WO2000006988A3

Abstract

A fluid flow regulator (10) including a resiliently collapsible tube (14) with an inlet for receiving a first fluid, and an outlet for accommodating a flow of the first fluid. The fluid flow regulator (10) also includes a flow regulating chamber (12) surrounding at least a portion of the resiliently collapsible tube (14), the flow regulating chamber (12) having a flow regulating fluid at a flow regulating pressure.

Description

SLOW HIΠD FLOW RΈHJOICR

FIELD OF THE INVENTION

The present invention relates to fluid flow control in general, and in particular to methods and apparatus for slow self-regulating fluid flow.

BACKGROUND OF THE INVENTION

Some fertility problems stem from low sperm count or inadequate flow of semen to the site of the ovum. Artificial insemination is often employed as a treatment for infertility whereby semen is injected into the uterus via the vaginal canal using an external syringe. Recent experiments with slow insemination techniques have resulted in significantly increased rates of conception. However, known slow insemination procedures are expensive and require that a patient lie down for several hours while an external syringe pump introduces the semen into the patient's vagina at a controlled rate and temperature.

U.S. Patent Nos. 5,536,243 and 5,562,654 are believed to be representative of the state of the art

SUMMARY OF THE INVENTION

The present invention seeks to provide novel apparatus and methods for slow self-regulating fluid flow for use, inter edict, in artificial insemination that overcome disadvantages of the prior an as discussed above. A small, portable, preferably disposable pump is provided where fluid, such as semen, is introduced into a resiliently collapsible chamber having a resiliently collapsible tube outlet with a pressure applied to the exterior of the chamber and the tube, resulting in a sclf-regulaung flow mechanism that is particularly suited to slow regulated flow techniques.

There is thus provided in accordance with a preferred embodiment of the present invention a fluid flow regulator including a resiliently collapsible tube having an inlet for receiving

I a First fluid thereat and an outlet for accommodating a flow of the first fluid therethrough, and a flow regulating chamber surrounding at least a portion of the resiliendy collapsible tube, the flow regulating chamber containing a flow regulating fluid at a flow regulating pressure.

Further in accordance with a preferred embodiment of the present invention the first fluid and the flow regulating fluid are identical and the flow regulating chamber is in fluid communication with the resflieπtly collapsible tube at the inlet at a location within the flow regulating chamber.

Still further in accordance with a preferred embodiment of the present invention the fluid flow regulator further includes a fluid reservoir containing the first fluid in fluid communication with the inlet of the resiliently collapsible tube.

Additionally in accordance with a preferred embodiment of the present invention the reservoir is at least partially housed within the flow regulating chamber and the an exterior of a wall of the reservoir is in pressure communication with the flow regulating fluid.

Moreover in accordance with a preferred embodiment of the present invention the fluid flow regulator further includes a fluid reservoir chamber located external to the flow regulating chamber and at least partially surrounding the fluid reservoir, the fluid reservoir chamber is in fluid communication with the flow regulating fluid and the an exterior of a wall of the fluid reservoir is in pressure communication with the flow regulating fluid at a location within the fluid reservoir chamber.

Further in accordance with a preferred embodiment of the present invention the fluid flow regulator further includes a pressure applicator operative to apply pressure at an exterior of a wall of the fluid reservoir.

Still further in accordance with a preferred embodiment of the present invention the first fluid is supplied to the inlet of the resiliently collapsible tube at a pressure substantially equal to the flow regulating pressure and the flow regulating fluid exerts a pressure at an exterior portion of the resiliently collapsible tube substantially equal to the flow regulating pressure. There is also provided in accordance with a preferred embodiment of the present invention a method of regulating fluid flow including providing a resiliently collapsible tube having an inlet for receiving a first fluid thereat and an outlet for accommodating a flow of the first fluid therethrough, and surrounding at least a portion of the resiliently collapsible tube with a flow regulating fluid at a flow regulating pressure the pressure at the inlet is substantially equal to pressure a

Further in accordance with a preferred embodiment of the present invention the method according further includes supplying the first fluid to the inlet of the resiliently collapsible rube at a pressure substantially equal to the flow regulating pressure and the flow regulating fluid exerts a pressure at an exterior portion of the resiliently collapsible tube substantially equal to the flow regulating pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated from the following detailed description, taken in conjunction with the drawings in which:

Fig. 1 is a simplified pictorial illustration of a self-regulating flow apparatus constructed and operative in accordance with a preferred embodiment of the present invention;

Fig. 2 is a graphical illustration useful in understanding the pressure-volume relationship for a segment of the resiliently collapsible tube 14 of Fig. 1;

Fig. 3 is a graphical illustration useful in understanding the nature of fluid flow through the resiliently collapsible tube of Fig. 1;

Fig. 4 is a simplified pictorial illustration of the flow apparatus of Fig. 1 inserted into the vaginal canal;

Fig. 5 is a simplified pictorial illustration of a self-regulating flow apparatus constructed and operative in accordance with another preferred embodiment of the present invention; Fig. 6 is a simplified pictorial illustration of a self-regulating flow apparatus constructed and operative in accordance with another preferred embodiment of the present invention; and

Fig. 7 is a simplified pictorial illustration of a self-regulating flow apparatus constructed and operative in accordance with another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to Fig. 1 which is a simplified pictorial illustration of self-regulating flow apparatus 10 constructed and operative in accordance with a preferred embodiment of the present invention. Flow apparatus 10, also referred to herein as a fluid flow regulator, preferably comprises a sealed chamber 12, also referred to herein as a flow regulating chamber, surrounding a tube 14. Chamber 12 is preferably constructed for receiving a pressurized fluid, such as air, water, or saline, through a wall of chamber 12 or through an inlet (not shown).

Tube 14 is preferably constructed in a suitable manner from a material or combination of materials such that tube 14 is resiliently collapsible at a given pressure of pressurized fluid introduced within chamber 12 that acts upon the exterior wall of rube 14, such as is described hereinbelow with reference to Figs. 2 and 3. The walls of sealed chamber 12 are preferably- constructed in a suitable manner from a material or combination of materials such that they deform less for a given pressure of pressurized fluid introduced within chamber 12 than do the walls of tube 14. Chamber 12 and tube 14 may be constructed from materials such as, but not limited to, silicon and plastic.

In the present embodiment flow apparatus 10 preferably comprises a fluid reservoir 16 for holding a fluid, such as semen. Fluid may be introduced into fluid reservoir 16 by, such as by syringe via a fluid inlet 18 that is in fluid communication with fluid reservoir 16. Fluid reservoir 16 is preferably in pressure communication with the interior of chamber 12 via a wall exterior of fluid reservoir 16. The walls of fluid reservoir 16 are preferably constructed in a suitable manner from a material or combination of materials such thai they deform more at a given pressure of pressurized fluid introduced within chamber 12 than do the walls of tube 14 thus collapsing fluid reservoir 16 and urging fluid contained therein to flow into tube inlet 24.

Tube 14 typically emerges from chamber 12 at an end 20 thereat and has a tube outlet 22 from which fluid flowing through tube 1 may emerge.

Row apparatus 10 is particularly useful in, but not limited to, artificial iriseminarion applications, intravenous fluid delivery applications, intravenous or other medicament delivery applications, or other non-medical fluid delivery applications.

A mathematical model describing the behavior of the flow apparatus of Fig. 1 is now presented with additional reference to Fig. 2 which is a graphical illustration useful in understanding the pressure-volume relationship for a segment of the resiliently collapsible tube 14 of Fig. 1, and Fig. 3 which is a graphical illustration useful in understanding the nature of fluid flow through the resiliently collapsible tube 14 of Fig. 1.

A quasi-static model is used to deteπnine the shift from .one steady state to another. Consider tube 14 divided into a segment of a length dx. The viscous element in each segment & is represented by Poiseuille resistance as follows:

where η represents fluid viscosity and r(x) is the tube radius as a function of the longitudinal coordinate jr. R(x), the flow resistance per unit length, can be expressed as a function of a constant Ro ("8ηπ) and the cross-sectional sιca.A(x :

«*»-;&> ^rø

Tra smural pressure of compliant tubes can be approximated by a sum of a logarithmic function and an exponential function of the cross-sectional area as is shown graphically in Fig. 2. The logarithmic term determines the relation in the low pressure range, and the exponent derermines the relation in the high pressure range. Experimentation has shown that the transmural pressure P ) within the tube is either a small positive pressure or a negative pressure. For this pressure range the pressure-cross-sectioπal area can be approximated by a logarithmic function of the cross-sectional area ^lA' as follows:

PΛx) = P(x) - P. =E In(^W) (3) where P(x) is the pressure inside the tube and P_t is the external pressure that is considered during the steady state derivation. E is an elasticity factor and t is a constant. The derivative of the pressure P'x) in the tube with respect to x due to viscous forces is expressed by:

l = -Q.R(x) (4)

where Q is volumetric flow. The boundary conditions are:

P(x) = P₀ f°r = 0 _($)

P{x) = P_L for x = l

The pressure-cross-sectional area (P_^-A) relation for a wall of the tube is approximated as follows:

PΛ*) = (x) - P. = EhiikAix ) (6) where P_t is external pressure.

The derivative with respect to x is: dP(x) E dA(x)

(7) dx A dx

This yields:

dA QR* (8) dx E A¹ EA

or

EAdA = -QRod (°)

Integrating Eq. 9 yields: ^E- Aⁱ ^ C₀ -OR_o -. (10)

Solving for A:

Atx=0; A(x}=Α(0)

From Eq. 3 we obtain:

FOΓJT- ):

Solving Eqs. 12 - 14 for Q yields a relation between flow and pressure as follows:

Q £_.(_β*Λ-^#.y^f - _eW>-W) (15)

The pressure at the distal end at JT-L, i, is imposed by external conditions as follows:

Q = ^£, H'.-W - _e*h-'.V) (16)

This solution relates inlet, outlet, and external pressures to fluid flow with the tube 14 's physical properties as parameters. A special case of interest is where the inlet pressure P₀ is equal to the external pressure.

Thus, in this special case we set P_ύ = P. . This yields the O-P relation shown in Fig 3 and expressed in Eq. 15 as follows:

where

= 2< £ (15a)

Fig. 3 shows graphically that the flow is constant for a large pressure range. This flow rate value is determined by the elasticity factor £. For lower E values the plateau begins at lower pressures and regulates flow at lower levels.

Fig. 4 is a simplified pictorial illustration showing flow apparatus 10 of Fig. 1 inserted into a vaginal canal 26 such as during an artificial insemination procedure. It is appreciated that the vaginal canal acts to heat the flow apparatus and the fluid contained therein with beneficial effect given that the flow apparatus is inserted into the vaginal canal.

Reference is now made to Fig. 5 which is a simplified pictorial illustration of self-regulating flow apparatus 30 constructed and operative in accordance with another preferred embodiment of the present invention. Fig. 5 shows flow apparatus 30-which preferably comprises a sealed chamber 32 surrounding a tube 34. Flow apparatus 30 is generally similar to flow apparatus 10 (Fig. 1) with the exception that no fluid reservoir 16 is employed. Rather, chamber 32 (chamber 12 in Fig. 1) is preferably constructed for receiving a pressurized fluid which enters tube 34 (tube 14 in Fig. 1) at a tube inlet 36 which is arranged to contact the pressurized fluid The pressurized fluid enters tube 34 and flows therethrough is in accordance with the principles described hcreinabove with reference to Figs. 2 and 3. Chamber 32 is also preferably constructed from a resilient material such that the walls of chamber 32 expand as the pressurized fluid is introduced into chamber 32 and contract as the fluid flows through tube 34.

Fig. 6 is a simplified pictorial illustration of self-regulating flow apparatus 40 constructed and operative in accordance with another preferred embodiment of the present invention Flow apparatus 40 preferably comprises a sealed chamber 42 surrounding a tube 44. Flow apparatus 40 additionally comprises a fluid reservoir 46 housed rπ a second sealed chamber 48, also referred to herein as a fluid reservoir chamber. A pressure conduit 50 connects chamber 42 and chamber 48 such that a pressurized fluid introduced into either of chambers 42 and 48 may flow through conduit 50 to achieve pressure equilibrium in both chambers. Bow apparatus 40 is generally similar to flow apparatus 10 (Fig. 1) with the exception that a fluid reservoir external to sealed chamber 42 (chamber 12 in Fig. 1) is employed. The pressure of pressurized fluid introduced within chambers 42 and/or 48 collapse fluid reservoir 46 thereby urging fluid contained therein to flow into tube 44 (tube 14 in Fig. 1) at a tube inlet 52. The flow of fluid through rube 44 is in accordance with the principles described hereinabove with reference to Figs. 2 and 3.

Reference is now made to Fig. 7 which is a simplified pictorial illustration of sclf-rcgularinε flow apparatus 60 constructed and operative in accordance with another preferred embodiment of the present invention. Flow apparatus 60 is generally similar to flow apparatus 30 (Fig. 5) with the exception that an external fluid reservoir 62 is provided A pressure applicator 68 may also be provided to surround fluid reservoir 62 and provide pressure to fluid reservoir 62. Fluid reservoir 62 typically holds a fluid, such as saline, and is preferably in fluid communication with the interior of a chamber 64 (chamber 12 in Fig. 1) that surrounds a tube 66 (tube 14 in Fig. 1). Pressure applicator 68 is typically a flexible cuff or other known force transmission medium suited for applying pressure to a flexible fluid-filled container such as fluid reservoir 62. Pressure applied to fluid reservoir 62 via pressure applicator 68 collapses fluid reservoir 62, introduces pressurized fluid into chamber 64, and urges the fluid to flow into tube 66 at a tube inlet 70. The flow of fluid through tube 66 is in accordance with the principles described hereinabove with reference to Figs. 2 and 3. Flow apparatus 60 is particularly useful in, but not limited to, intravenous applications.

It is appreciated that various features of the invention which are, for clarity, described in the contexts of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable subcombination. It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention is defined only by the claims that follow:

Claims

What is claimed is:

1. A fluid flow regulator comprising; a resiliently collapsible tube having an inlet for receiving a first fluid thereat and an outlet for accommodating a flow of said first fluid therethrough; and a flow regulating chamber surrounding at least a portion of said resiliently collapsible tube, said flow regulating chamber containing a flow regulating fluid at a flow regulating pressure.

2. A fluid flow regulator according to claim 1 and wherein said first fluid and said flow regulating fluid are identical and wherein said flow regulating chamber is in fluid communication with said resiliently collapsible tube at said inlet at a location within said flow regulating chamber.

3. A fluid flow regulator according to claim 1 and further comprising a fluid reservoir containing said first fluid in fluid communication with said inlet of said resiliently collapsible tube.

4. A fluid flow regulator according to claim 3 wherein said reservoir is at least partially housed within said flow regulating chamber and wherein an exterior of a wall of said reservoir is in pressure communication with said flow regulating fluid.

5. A fluid flow regulator according to claim 3 and further comprising a fluid reservoir chamber located external to said flow regulating chamber and at least partially surrounding said fluid reservoir, wherein said fluid reservoir chamber is in fluid communication with said flow regulating fluid and wherein an exterior of a wall of said fluid reservoir is in pressure communication with said flow regulating fluid at a location within said fluid reservoir chamber.

6. A fluid flow regulator according to claim 3 and further comprising a pressure applicator operative to apply pressure at an exterior of a wall of said fluid reservoir.

7. A fluid flow regulator according to any of the preceding claims and wherein said first fluid is supplied to said inlet of said resiliently collapsible tube at a pressure substantially equal to said flow regulating pressure and wherein said flow regulating fluid exerts a pressure at an exterior portion of said resiliently collapsible tube substantially equal to said flow regulating pressure.

8. A method of regulating fluid flow comprising: providing a resiliently collapsible tube having an inlet for receiving a first fluid thereat and an outlet for accommodating a flow of said first fluid therethrough; and surrounding at least a portion of said resiliently collapsible tube with a flow regulating fluid at a flow regulating pressure wherein pressure at said inlet is substantially equal to pressure a

9. A method according to claim 8 and further comprising supplying said first fluid to said inlet of said resiliently collapsible tube at a pressure substantially equal to said flow regulating pressure and wherein said flow regulating fluid exerts a pressure at an exterior portion of said resiliently collapsible tube substantially equal to said flow regulating pressure.

10. A method substantially as described hereinabove.

11. A method substantially as illustrated in any of the drawings.

12. Apparatus substantially as described hereinabove.

13. Apparatus substantially as illustrated in any of the drawings.