Three-dimensional hose clamp for shear-sensitive liquids

Abstract

Device for regulating the flow of a liquid through an elastic hose and / or for generating a desired flow through the hose, wherein the device has two clamping jaws which are movable relative to one another and between which the hose is arranged and can be squeezed when used as intended, wherein a first clamping surface of the first clamping jaw and a second clamping surface of the second clamping jaw are in contact with the hose, characterized in that the first clamping surface and the second clamping surface have contour lines corresponding to curved profiles with the same direction of curvature and with a convex-concave course, seen in the direction of flow through the hose.

Description

[0001] The invention relates to a device according to claim 1 or claim 2, in particular a three-dimensional hose clamp for shear-sensitive liquids.

[0002] In medical and clinical settings, especially during extracorporeal perfusion, controlling blood flow through tubing is critical. Traditional methods, such as the Hoffmann clamp, are widely used but carry a significant risk of hemolysis and thrombosis due to sudden changes in the cross-sectional area of ​​the fluid pathway.

[0003] The Hoffmann clamp and similar devices, such as a standard surgical clamp, exert significant shear stress on blood cells. This contributes to increased hemolysis and thrombus formation due to sudden cross-sectional changes and turbulence in blood flow. See also: M. Schöps, J.C. Clauser, T. Schmitz-Rode, U. Steinseifer, and J. Arens, "Standard Hemolysis Tests: Is the Resistance's Design a Problem?", 46th ESAO Congress, September 3-7, 2019, Hannover, Germany, 2019.

[0004] Fig. Figure 1 shows a sudden change in the flow path caused by a state-of-the-art Hoffmann clamp. The flow pattern of a hose compressed with a standard Hoffmann clamp is shown.

[0005] Fig. Figure 2 shows a cross-sectional view of the result of clamping with a state-of-the-art Hoffmann clamp. As the Hoffmann clamp begins to compress the hose, the cross-section of the hose changes from its natural circular shape to an increasingly flattened shape. At this stage, the shape may resemble an elliptical or oval slit as the two sides of the hose are pressed together.

[0006] As the clamping force continues to increase, the center of the hose flattens more and more. However, instead of creating a simple straight slit, the flexible nature of the hose material, such as PVC or silicone, causes the hose walls to bulge outward on either side of the flattened center and bulge inward toward each other in the center.

[0007] This results in an eight-shaped opening with: a central slit: due to the given circular cross-section in combination with the stiffness of the hose, a narrow slit is formed in the middle • larger open side areas: On both sides of this slot, the tube walls expand outwards, creating two rounded sections - these are the "loops" of the figure-eight opening.

[0008] As the clamp is tightened further, the slot narrows and the bulge on both sides becomes more pronounced, further enhancing the figure-eight opening. This shape is due to the mechanical properties of the hose material (elasticity and flexibility), which force the sides to expand outward when compressed. In its extreme form, the two bulges are no longer connected, resulting in two completely separate fluid paths in the clamping area of ​​the hose.

[0009] An adjustable, optimized flow resistance is known as a compensator valve for carbonated beverages, which internally creates a conically adjustable annular gap through two cones. This gap continuously distributes the induced pressure drop across the entire flow length of the annular gap. An exemplary valve design is shown in Fig. 3. The figure is taken from DE102015014008A1. It shows a tap with a compensator as a pressure and flow control element, which has a spring-loaded pressure tappet.

[0010] However, direct contact with the flowing liquid has the disadvantage that this component must be regularly cleaned or sterilized to prevent contamination of the flowing liquid. In addition, there are stagnant zones in parts of the tap due to its design, which are necessary for the cone adjustment mechanism.

[0011] Several different clamps already exist in the field of perfusion for blood lines. Reference is also made to the following publications: Qosina, “BioValve,” [Online]. Available at: https: / / www.qosina.com / biovalve-51613. D. Buchwald, M. Bongert, and J. Wüst, "New tube clamp for atraumatic regulation of blood flow," PROVendis, July 14, 2021. [Online]. Available: https: / / provendis.info / aktuelles / presse / artikelansicht / neue-schlauchklemme-zuratraumatischen-regulierung-des-blutflusses. M. Bongert, J. Wüst, and D. Buchwald, “Tube clamp for flow control with reduced blood trauma.” German patent application DE102019008056A1 and German patent DE102019008056B4, respectively. G. Wengqing and L. Tong, "ECMO pipeline reducer." Chinese patent CN219290292U, 17 November 2022.

[0012] Fig. Figure 4 shows an example of Qosina with an equidistant gap in the transverse direction, but not in the longitudinal direction, in a transverse view. See Qosina, "BioValve," [Online]. Available: https: / / www.qosina.com / biovalve-51613.

[0013] Fig. Figure 5 shows a hose clamp from Cormed / University of Dortmund with a gradual narrowing and widening of the gap in the longitudinal direction, but no gap change in the transverse direction, so that the figure-eight cross-section is still to be expected. In particular, a hose clamp from Cormed / University of Dortmund is shown as schematics (left) and as a prototype (right) (longitudinal view).

[0014] It is an object of the present invention to provide an improved clamp.

[0015] The object is achieved by a device, in particular a clamp, further in particular a hose clamp, having the features of claim 1 or by a device having the features of claim 2. Preferred developments and refinements of the invention are specified in the dependent claims. Embodiments of such a clamp are also referred to below as NAFRI clamps.

[0016] A clamp according to the invention, in particular hose clamps, is provided in particular for forming a variable constriction of an elastic hose for conveying liquids, wherein the constriction is achieved by two mutually perpendicular curved profiles.

[0017] Variants of the clamp according to the invention may have a novel clamp design that aims to reduce risks by providing a smoother closure mechanism both in the longitudinal direction, i.e. along the tube profile, and in the transverse direction, i.e. through the tube cross-section or perpendicular to the longitudinal direction, thereby reducing hemolysis.

[0018] The curve profiles can be parabolic or circular. The curve profiles can cause a constriction that essentially represents an equidistant nonlinear gap in cross-section. The curve profiles can cause a continuous narrowing or expansion of the resulting gap cross-section. Closing and opening can be achieved by a threaded mechanism, a lever mechanism, a wedge mechanism, and / or by motorized, hydraulic, pneumatic, or other actuators.

[0019] From the above-mentioned prior art, no clamp is known that addresses two curvatures in two perpendicular directions, in contrast to variants of the clamp according to the invention.

[0020] The invention is explained in more detail below using exemplary embodiments and drawings. The drawings show: Fig. 1 the sudden change of the flow path caused by a Hoffmann clamp known from the state of the art. Fig. 2 the result of clamping with a Hoffmann clamp known from the state of the art in a sectional view. Fig. 3 a representation of a tap known from the prior art. Fig. 4 a prior art example of Qosina with an equidistant gap in the transverse direction, but not in the longitudinal direction, in a transverse view. Fig. 5 a hose clamp known from the prior art with a gradual narrowing and widening of the gap in the longitudinal direction, but without gap change in the transverse direction. Fig. 6 sectional views of a variant of a clamp according to the invention in the transverse plane (upper images) and the longitudinal plane (lower images) in different states (open to closed). Fig. 7 a technical 3D CAD model and a manufactured prototype of a variant of a clamp according to the invention. Fig. 8 Longitudinal sectional view of a variant according to the invention with clamping jaws in tapered and widened areas that can be adjusted independently of each other; the special case with only one area (only tapered or only widened) is also provided. Fig. 9 Components of a variant of a clamp according to the invention, which serves as a demonstrator, in a transverse view. Fig. 10 casts of tube lumens showing the presence of the desired flow path geometry. Fig. 11 a comparison of a variant of a clamp according to the invention (NAFRI) and a standard Hoffmann clamp known from the prior art with regard to repeatability.

[0021] A variant of the clamp according to the invention, specifically the NAFRI clamp, was originally developed for human blood tests with very low flow rates relative to the tube size. One feature is the compression of the tube using two bends of different diameters, so that the two tube walls perfectly conform to the surroundings and a teardrop-shaped open lumen is not created at both the upper and lower ends of the tube cross-section, as would be the case with planar clamps. Furthermore, it features two bends of different diameters in a vertical direction to constrict the blood flow path as gently as possible and then widen it again after the constriction.

[0022] Fig. Figure 6 shows sectional views of a variant of a clamp according to the invention in the transverse plane (upper images) and the longitudinal plane (lower images). The upper left image shows the clamp including the diameter of the unclamped hose. The upper right image shows the hose fully clamped between two clamping jaws of the clamp. The lower row shows sectional views in the longitudinal plane, illustrating the clamp with the clamping jaws in the open, half-open, and closed positions (without hose).

[0023] The design leads to a reduction in hemolysis, as the continuous narrowing or widening of the constriction gap, according to the Bernoulli principle, results in only a continuous local increase or decrease in flow and thus also a decrease or increase in pressure. This minimizes the local velocity changes and thus the local pressure changes and shear stresses experienced by a passing particle or cell. This minimization of shear stress results in reduced hemolysis.

[0024] A variant of a clamp according to the invention, a so-called demonstrator, was manufactured for demonstration purposes. The demonstrator confirmed the potential of the disclosed approach and found that there was no figure-eight deformation of the hose. Instead, the hose exhibited equidistant, nonlinear "curved-parallel" walls, as intended. The resulting flow path in cross-section is kidney-shaped.

[0025] Fig. Figure 9 shows the components of this demonstrator, particularly in a transverse view, including the fixed black wall, which here acts as one clamping jaw, with a concave profile (left) and the steel rod - designed at a later stage as movable - which here acts as the other clamping jaw, with a convex profile and reduced diameter (right), which acts on the hose positioned between them.

[0026] Fig. Figure 10 shows casts of tubing lumens demonstrating the presence of the desired flow path geometry.

[0027] Several fluid path casts were created by filling standard hoses with liquid polyurethane (PU), applying the inventive clamp at different degrees of closure (from fully opened / expanded to fully closed / constricted), and curing the PU before removing the PVC hose.

[0028] A careful examination of these casts revealed that instead of a droplet or figure-eight shape, the cross-sectional area (= transverse) maintained a constant distance with equidistant nonlinear thickness, which narrows steadily and evenly and widens again evenly after the constriction.

[0029] The clamp according to the invention has also been successfully used in several internal hemolysis test setups.

[0030] In general, repeatability is crucial in automation and control systems. Repeatability ensures that a system can consistently return to the same position, which is crucial for precise control and regulation.

[0031] Compared to a Hofmann clamp known from the state of the art, the disclosed clamp (NAFRI) shows a significantly better repeatability in measuring the flow rate as a function of the number of turns of the clamping screw ( Fig. 11) against a constant pressure behind the clamp.

[0032] Fig.Figure 11 specifically shows a comparison of the proposed clamp (NAFRI) and the standard Hoffmann clamp in terms of repeatability. An identical line type indicates a new measurement in the installed state; a new line type (interrupted, continuous) indicates the results after removing and reattaching the clamp. The improved repeatability, both in the installed state and, above all, the insensitivity to reassembly of the NAFRI clamp, simplifies potential automatic control and regulation when the clamping position is controlled by a motor. The accuracy may even be sufficient to be used without flow measurement.

[0033] There is potential to implement the clamp as a disposable item within a future tubing set, e.g. for hybrid / VAV ECMO.

[0034] A variant of the clamp was originally developed for a 1 / 4-inch hose. Later, a modification for 3 / 8-inch hoses was realized. The concept is applicable to all hose sizes (regardless of diameter and wall thickness), as long as the wall material is flexible.

[0035] The clamp can also be useful for transport and processing in any type of circuit where shear-sensitive fluids are used, especially since it allows for easy cleaning / replacement.

[0036] Examples include, but are not limited to: • Food industry, e.g. the beverage industry mentioned above, but also dairy products, sauces, etc. • Pharmaceuticals / Cell Culture / Vaccines & Life Sciences Applications. • Cosmetics & Body Care: Creams, shampoos, gels and other topical products • Chemical processing: polymers & latex; dyes & pigments • Oil extraction processes / gas industry • Ceramics & Sludges

[0037] Further preferred embodiments and developments of the invention are listed below: 1. Means for forming a variable constriction of an elastic hose for conveying liquids, wherein the constriction is characterized by two mutually perpendicular curved profiles. 2. Mean according to point 1, where the curve profiles are parabolic. 3. Means according to point 1, whereby the curve profiles are circular. 4. Means according to any one of the preceding points, wherein the curved profiles cause a constriction which in cross-section essentially represents an equidistant non-linear gap. 5. Means according to one of the preceding points, wherein the curved profiles cause a continuous narrowing or widening of the resulting gap cross-section. 6. Means according to one of the preceding points, wherein the closing and opening is effected by a threaded mechanism. 7. Means according to one of the preceding points, wherein the closing and opening is effected by a lever mechanism. 8. Means according to one of the preceding points, wherein the closing and opening is effected by a wedge mechanism. 9. Means according to any one of the preceding points, wherein the closing and opening is effected by motorized, hydraulic, pneumatic or other actuators. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 102015014008A1

[0009] DE 102019008056A1

[0011] DE 102019008056B4

[0011] Cited non-patent literature

[0000] M. Schöps, J.C. Clauser, T. Schmitz-Rode, U. Steinseifer, and J. Arens, “Standard Hemolysis Tests: Is the Resistance's Design a Problem?”, 46th ESAO Congress, 3-7 September 2019, Hannover, Germany, 2019

[0003] https: / / www.qosina.com / biovalve-51613 [0011, 0012] D. Buchwald, M. Bongert, and J. Wüst, "New tube clamp for atraumatic blood flow regulation," PROVendis, July 14, 2021. [Online]. Available: https: / / provendis.info / aktuelles / presse / artikelansicht / neue-schlauchklemme-zuratraumatischen-regulierung-des-blutflusses

[0011] M. Bongert, J. Wüst and D. Buchwald, “Tube clamp for flow control with less blood trauma”

[0011] G. Wengqing and L. Tong, "ECMO pipeline reducer." Chinese patent CN219290292U, 17 November 2022

[0011]

Claims

[1] Device for regulating the flow of a liquid through an elastic hose and / or for generating a desired flow through the hose, wherein the device has two clamping jaws movable relative to each other, between which the hose is arranged and can be squeezed when used as intended, wherein a first clamping surface of the first clamping jaw and a second clamping surface of the second clamping jaw are in contact with the hose, characterized by that the first clamping surface and the second clamping surface have contour lines corresponding curve profiles with the same direction of curvature with a convex-concave course, seen in the direction of flow through the hose. [2] Device for regulating the flow of a liquid through an elastic hose and / or for generating a desired flow through the hose, wherein the device has two clamping jaws which are movable relative to one another and between which the hose is arranged and can be squeezed when used as intended, wherein a first clamping surface of the first clamping jaw and a second clamping surface of the second clamping jaw are in contact with the hose, in particular a device according to the preamble of claim 1, characterized bythat the first clamping surface and the second clamping surface have contour lines corresponding to curve profiles with the same direction of curvature with a convex-concave course, seen in the cross-sectional direction of the hose, in particular seen perpendicular to the curve profiles in the flow direction of the hose, so that in the squeezed hose a flow cross-section is produced which is continuously changed in the flow direction and which essentially represents a non-linear equidistant gap. [3] Device according to claim 1 or 2, wherein the curve profiles are parabolic. [4] Device according to claim 1 or 2, wherein the curved profiles are circular. [5] Device according to one of the preceding claims, wherein the curved profiles cause a constriction, in particular of the hose arranged therebetween, which in cross-section essentially represents an equidistant non-linear gap. [6] Device according to one of the preceding claims, wherein the curved profiles cause a continuous narrowing or expansion of the resulting gap cross-section, in particular of the hose. [7] Device according to one of the preceding claims, wherein the closing and opening of the clamping jaws is effected by a threaded mechanism. [8] Device according to one of the preceding claims, wherein the closing and opening of the clamping jaws is effected by a lever mechanism. [9] Device according to one of the preceding claims, wherein the closing and opening of the clamping jaws is effected by a wedge mechanism. [10] Device according to one of the preceding claims, wherein the closing and opening of the clamping jaws is effected by motorized, hydraulic, pneumatic or other actuators.

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