WO2009065552A1

WO2009065552A1 - Medical tube

Info

Publication number: WO2009065552A1
Application number: PCT/EP2008/009737
Authority: WO
Inventors: Ulrich Pfeiffer; Reinhold Knoll; Tobias THOMAMÜLLER; Daniel Moulas
Original assignee: Iprm Intellectual Property Rights Management Ag
Priority date: 2007-11-21
Filing date: 2008-11-18
Publication date: 2009-05-28
Also published as: KR20100098404A; EP2222361A1; DE102007055675A1; CA2706984A1

Abstract

Medical tube (10), having an outer periphery (12), a tube wall (13), a first lumen (30.1) with a first inner surface (11.1), a second lumen (30.2) with a second inner surface (11.2), wherein the lumens (30.1, 30.2) are separated by a dividing wall (31), wherein the first lumen (30.1) has a D-shape in a cross sectional view to the axis (17) of the medical tube (10) and the first inner surface (11.1) of the first lumen (30.1) has at least one projection (20), thus defining a maximum inner circle (11.5) with an inner circle diameter (11.3) which touches at least three limitative points (51, 52, 53) of the first inner surface (11.1) of the first lumen (30.1).

Description

Medical Tube

The invention relates to a medical tube, especially a flexible medical tube with enhanced stiffness.

In medicine, a catheter is a tube that can be inserted into a body cavity duct or vessel. Catheters thereby allow drainage or injection of fluids or access by surgical instruments. In most uses a catheter is a thin, flexible tube: a "soft" catheter; in some uses, it is a larger, solid tube: a "hard" catheter.

Soft catheters have the advantage of high adaptability and low risk of injury by easily passing through turnings and curves. However, the soft catheter is subject to kinking behaviour when inserted. Thus, a lumen can be blocked. Further, the soft inside of such a catheter can be damaged when exercising the seldinger technique.

In DE 102 60 761 Al a catheter with a catheter corpus is described, whose inside builds a first catheter lumen which serves to accommodate a guide wire during the injection of the catheter into the human body, with at least one dividing wall in the inside which divides the inside into at least one more catheter lumen.

Further, US patent 5,593,394 describes a shaft of a catheter system used for a PTCA, angiography, perfusion, drug delivery or the like in a body of a patient. Thereby the shaft is formed of a tube and a plurality of ribs projecting from an inner wall of the tube towards a centre thereof. Furthermore, US patent 2006/0161135 Al describes a catheter for delivering medication from a fluid source to an anatomical site of a patient. Therefore, the catheter comprises an elongated tube having an outer wall extending between an open proximal end and a closed distal end of the elongated tube and an inner wall coaxially disposed within the outer wall.

Object to the present invention was to provide a medical tube with enhanced properties, provide a lumen with less friction for guide wire applications and reduce kinking behaviour.

The object of the present invention is achieved by a medical tube (10), having an outer periphery (12), a tube wall (13), a first lumen (30.1) with a first inner surface (11.1), a second lumen (30.2) with a second inner surface (11.2), wherein the lumens (30.1, 30.2) are separated by a dividing wall (31), wherein the first lumen (30.1) has a D-shape in a cross-sectional view to the axis (17) of the medical tube (10) and the inner surface (11.1) of the first lumen (30.1) has at least one projection (2), thus defining a maximum inner circle (11.5) with a inner circle diameter (11.3) which touches at least three limitative points (51, 52, 53) of the first inner surface (11.1) of the first lumen (30.1).

This configuration gives the possibility to produce a catheter tube, having a soft surface to avoid lesion during medical application and being stiff enough to prohibit kinking behaviour and closing of a catheter lumen.

Medical tubes are tubes in medicine for preferably transporting liquids, particulate material, fluids or medical equipment. In general, medical tubes are manufactured in tight tolerances, as they are applied in sensitive fields. The field of the application can be outside or inside of the human body.

"Hard" tubes are preferably used in applications outside the human body, whereas soft tubes and flexible tubes preferably find application inside the human body. Their soft and flexible structure makes it easier to navigate through cavity ducts without creating lesion.

The usage of medical tubes is mostly singular, but can also be permanent when resting inside the human body, as e.g. a bypass.

In a preferred embodiment the medical tube is a flexible tube, a catheter tube, a diagnostic catheter tube, a therapeutic catheter tube, a cerebrovascular catheter tube, an ultrasonic catheter tube, an infusion tube, a connecting tube or a synthetic tube. Most preferably, the medical tube is a soft catheter tube, e.g. a flexible tube.

Materials used to produce medical tubes are for example several variations of polymers, preferably polyurethane with a shore hardness between 6Od and 85d. With this material for the catheter tube it is found that on the one hand, the catheter demonstrates satisfactory stiffness and, on the other hand, reliable antilock sliding of the catheter relative to the guide wire disposed in the first catheter lumen is possible.

The outer periphery of the medical tube is a geometric self contained area shaping an exterior surface, limiting the medical tube to the ambient medium. The preferred properties of the outer periphery are antibacterial and/or smooth and/or soft and/or plain and/or tear proof. The material used for the outer periphery is preferably the same material as for the rest of the catheter tube, making production simpler and cheaper. More preferably the outer periphery has a different material from the rest of the catheter tube to enhance the physical properties of the outer periphery. For example with special coatings lower friction coefficients can be achieved. These coatings are for example any antiseptic or hydrogel coatings or polyurethane coatings or silicone coatings or a type of TPE coatings.

The outer periphery preferably has the geometric shape of an ellipsis, more preferably the geometric shape of a circle, when regarding the catheter tube in a cross sectional view to the axis.

The centre point of the medical tube is the cross section of the middle axis of the medical tube. This centre point is called medical tube centre. If the outer periphery is a circle, the centre point of the circle is the medical tube centre. If the outer periphery is an ellipsis the centre point of the ellipsis is the medical tube centre.

If the medical (outer periphery) is a circle, the distance between the medical tube centre and the outer periphery is then called outer radius. The length of the outer radius is preferably in the interval of 0,1mm to 5mm, more preferably from 0,2mm to lmm, most preferably from 0,3 to 0,6mm.

The tube wall separates the lumens from the outer medium, which is situated outside of the outer periphery. The tube wall can derive in an axial point of view, as the first and the second lumen can take different sizes and shapes. The tube wall can be defined as the sum of points of a distance on a straight line between the outer periphery and the medical tube centre, from the outer periphery to the nearest lumen, when circling this straight line around the medical tube centre. The area spun with those distances is called the tube wall. The smallest distance on this circling, straight line between the outer periphery and the nearest lumen is the minimal thickness D of the medical tube. The thickness of the tube wall is to be seen as an average thickness. The thickness of the tube wall can vary either over a cross- sectional view to the axis or in direction of the axis. But when talking about the thickness of the tube wall in this document, the minimal thickness as described above is meant.

The thickness of the tube wall is preferably between 0,1 mm and 1 mm, more preferably between 0,05 mm and 0,8 mm, most preferably between 0,01 mm and 0,15 mm.

The medical tube comprises a first lumen with a first inner surface. The first inner surface of said medical tube is a self-contained area in a cross sectional view defining the first lumen. The first lumen is preferably used for guide wire applications, meaning that for example a wire is used through this first lumen. In that case it is of importance that friction inside the first lumen is low and piercing of the first inner surface of the first lumen is avoided.

Preferably the first inner surface consists of the same material as the rest of the medical tube, which makes production easy and reduces costs. More preferably the first inner surface is of a different material than the rest of the medical tube. With for example a special coating, physical properties such as friction can be lowered. The first lumen has a D-shape in a cross sectional view. The D-shape is defined by a chord as a straight line building the straight part of the "D" and by a segment of a circle or ellipsis, which forms the curved part of the D-shape.

More preferably, two curved parts can exist next to each other. Most preferably the chord and the curved part or several curved parts form a D-shape like first lumen. For example if one chord and two curved parts form a lumen, the first end of the first curved part is attached to the first end of the chord and the second end of the first curved part is attached to the first end of a second curved part and the second end of the second curved part is attached to the second end of the chord, forming a shape similar to a "B". Most preferably, several curved parts can be attached to each other forming a cloud-shape on one side, connected to the chord on the other side. The attachment point between the curved parts of this varied D-shape can either have harmonic changeovers or changeovers with pointy peeks. Those pointy peeks or harmonic changeovers, facing to the inside of the first lumen can also be called projections. The chord-side of the first lumen preferably faces towards the second lumen or is near the second lumen forming a separating wall between the two inner surfaces.

The second lumen respectively the second inner surface has any geometric shape, preferably a circular shape in a cross sectional view. If the second lumen has a circular shape, the second inner surface is defined by a second inner radius around a centre point called second centre point. Through the second lumen it is possible to deliver different components from the first lumen. For example, contemporaneous measurements such as thermal dilution measurement and pulse pressure measurement, can take place inside the second lumen. It is also possible that a temperature sensor is part of said lumen as well as blood for pressure measurement. For parting the medical equipment and the bodily fluid more then one lumen is used. Preferably the second lumen has an area 1/3 the size of the first lumen, more preferably 1/5, most preferably 1/7 the size.

The D-shaped first lumen is separated from the second lumen with a second inner surface by a dividing wall. The dividing wall is defined as the area that separates the first lumen from the second lumen. As the first inner surface and the second inner surface do not run parallel to each other in most cases, the thickness of the separating wall is defined as the minimum distance between the first inner surface and the second inner surface.

At least two projections are provided on the inner surface of the first lumen.

A projection is an elevation of material on the inner surface of the first lumen, preferably facing towards the middle of the first lumen. The height h of a projection is measured rectangular between two parallel lines Ll and L2 setting limits to top and base of the projection. The two lines Ll and L2 are straight lines. Ll is defined as a base line, described by two intersection points Il and 12. Il and 12 are the intersection points between the first inner surface and the boundary line of a projection. L2 includes the farthest possible point P to Ll, being part of the projection.

The width of a projection is the distance between the intersection points Il and 12. The preferred ratios between the distance I112 and the height h are for example 2:1, 3:2, 1:1, 2:3, 1:2, 1:3, 1:5. The width of the projection at a height hl=h*0,5 is preferably 140%, more preferably 100%, most preferably 70% of the distance 11-12.

Said projections minimize the contact surface, for example during a guide wire application, with medical equipment. This means less friction and canting and therewith brings important timesaving during surgery. An important benefit of the projections is the additional safety, as the guide wire cannot get stuck inside the tube, during the application. Through said projections the tube wall is strengthened and mechanical stress is taken from the medical tube. In addition, the projections stabilize the physical properties of the medical tube, as less material is used in the half of the catheter tube where the D-shaped first lumen is located.

Another advantage is, that with projections, preferably a medical instrument can be held in one fixed rotation position during insertion. The circular motion of the medical instrument can be prohibited if the medical instrument possesses an adequate cross sectional shape (for example a guidance which matches the shape of said projections).

Also kinking behaviour and tube closing can be prevented by the projections. In addition, piercing of the tube wall is more likely to be avoided by increasing the distance of the medical equipment (for example a guide wire), through said projections from the first inner surface. If the physical properties (e.g. stiffness) of a medical tube without projections are sufficient, a medical tube with projections can reach the same or better physical properties needing less material in the manufacturing process in order to save money, because material can be saved at the tube wall. The first inner surface and the at least two projections define a maximum inner circle with an inner circle diameter which touches at least three limitative points of the first inner surface of the first lumen. The maximum inner circle is defined as a circle with a maximum possible radius fitting into the first lumen. By choosing the maximum possible radius of the maximum inner circle, the maximum inner circle touches at least three points of the first inner surface of the first lumen. The first inner surface contains the surface of the projections as well as the chord of the D-shape.

The maximum inner circle preferably describes the maximum diameter of medical equipment, which is pushed through the first lumen. If medical equipment would be larger in diameter then the inner maximum circle, the minimum three limitative points would exercise pressure onto the medical equipment, increasing friction. The optimum diameter of medical equipment is little less then the diameter of the maximum inner circle, except the medical equipment has a guidance, which fits the projections.

With regard to reliable sliding of the guide wire, it has proven to be advantageous if the guide wire has a diameter that amounts to 65-95% of the diameter of the maximum inner circle. The maximum inner circle describes an area, which is preferably 40%, more preferably 60%, most preferably 80% of the area described by the cross-section of the medical tube.

In another preferred embodiment the D-shape of the lumen comprises a circular segment or an elliptic segment (11.4) and a chord (14).

The first lumen has a D-shape in a cross sectional view. The D-shape is defined by a chord as a straight line building the straight part of the "D" and by a segment of a circle or ellipsis, which forms the curved part of the D-shape. Preferably the centre point of the ellipsis or the circle, describing the curved part of the "D" is the medical tube centre. The curved line of the "D" is partly part of an ellipsis or circle. The curved part of the "D" preferably describes circa 45% of the, more preferably 60%, most preferably 85% of the distance of the first inner surface in a cross sectional view.

In a preferred embodiment the chord (14) provides at least one projection (20), preferably provides at least two projections (20.3, 20.4).

With one projection on the chord and two further projections on the inner surface of the first lumen (on the curved part of the "D") the optimum of friction to guidance is reached for medical equipment having a diameter of little less then the diameter of the maximum inner circle.

Preferably the chord provides at least two projections. The more projections the chord provides, the more variation in medical equipment diameter is possible. If more then two projections guard the chord of the first lumen, diameters of medical equipment a lot smaller then the diameter of the maximum inner circle are possible and piercing of the tube wall or the separating wall is more likely to be prevented.

Preferably not only the chord provides more then two projections. A jagged inner surface described by many projections makes any diameter of medical equipment possible, which is smaller than the maximum inner circle. If the medical tube provides two projections on the chord of the first lumen, the projections preferably have the same height of ca. 0,1mm to 0,3mm and a distance of ca. 0,2mm to 0,6mm, preferably 0,4mm to each other. The two projections have the same distance from the middle of the chord.

In a further preferred embodiment the projections (20) have a shape and a position on the chord, that at least three limitative points (51, 52, 53) of the maximum inner circle (11.5) are situated at the projections.

If the limitative points are situated at the projections, optimal guidance of medical equipment and low friction is guaranteed. During, for example a guide wire application the medical equipment then runs along the projections, without touching the tube wall. If the limitative points are situated at the projections, piercing of the tube wall can be avoided more easily.

In another preferred embodiment the total number of projections (20) is three or four.

In another preferred embodiment two of the projections (20.1, 20.2) provided on the first inner surface (11.1) include an angle of 120° +/- 30°, measured from a centre point (15) of the medical tube (10).

The centre point of the medical tube is the centre point of the geometrical shape, which defines the outer periphery. From the centre point the angle is measured to the tips of the projections. The tip of a projection is the highest point of a projection, measured rectangular from its base line. Preferably those projections present a counterpart to the second lumen. Meaning that, the second lumen is preferably smaller than the lumen providing the projections. Consequently, the material volume around this smaller lumen is higher than the material volume around the other lumen. This brings physical misbalance when regarding the cross section of the medical tube. The physical properties of the first half of the medical tube (containing the smaller lumen) are different to the properties of the second half (containing the larger lumen) . Preferably projections in a certain constellation including a 120° +/- 30° angle, compensate this misbalance. Preferably the bisecting line of the angle between the tube projections preferably subtends the centre point of the smaller lumen. Thus, an equal bending behaviour can be provided in all directions (from a two—dimensional cross section point of view) . Preferred angles between the projections are 90° or 100° or 110° or 120° or 130° or 140° or 150°.

In a further preferred embodiment the medical tube (10) has an outside diameter (12.1) wherein the ratio of the outside diameter (12.1) to the inner circle diameter (11.3) of the maximum inner circle (11.5) is 2 to 1.

The outside diameter of the medical tube is a straight line segment that passes through the centre of the medical tube and whose endpoints are on the outer periphery. If the shape of the medical tube should be different from a circle, the outer diameter is the maximal possible length of this straight line.

The inner circle diameter is the diameter of the maximum inner circle. The ratio of outside diameter to the diameter of the maximum inner circle is 2 to 1

In a preferred embodiment the height (h) of said projections (20) is 30 % to 200 % of the thickness of the medical tube wall (13), more preferably 70 % to 120 % or most preferably 90 % to 110 %.

The thickness of the tube wall was already described above. Most preferably for the given percentages the thickness is defined as the average thickness of the medical tube wall. The height of the projection is measured excluding the thickness of the medical tube wall.

In a further preferred embodiment said projections (20) have the shape of a triangle, a trapezium (British definition of the word; imperative for following use) or a segment of a circle.

Preferably, the projections are geometric forms (in a cross sectional view to the axis) with tapering shapes while extending from the first inner surface in direction towards the centre of the medical tube.

In a preferred embodiment the shapes of said projections are segments of a circle, as harmonic shapes without sharp edges deliver better quality results in the manufacturing process.

In a further preferred embodiment the shapes of said projection ( s ) are segments of an ellipsis, as harmonic shapes without sharp edges deliver better quality results in the manufacturing process.

In another preferred embodiment the shapes of said projections have pointy edges, e.g. the triangle shape, which has the advantage of best guidance and minimum friction, as the contact surface with medical equipment is minimized, preconditioned that the diameter of the medical equipment is marginal smaller than the diameter of the circle described by said projections and the allocation of said projections is consistent. In a further preferred embodiment the shape of said projections is a trapezium. The trapezium shape of said projections produces a little more friction, but has the advantage of better guidance of medical equipment compared to the same number of triangle shaped projections, when the medical equipment's diameter is smaller (to a certain degree) than the diameter of the circle described by said projections.

In other embodiments further shapes of said projections can be combinations of the mentioned basic shapes. A change of projection shapes is also possible along the catheter axis providing a variation of physical properties.

In a further preferred embodiment said medical tube (10) is made of a material identical to the material of said projections (20).

As medical tubes are in general produced in an extrusion manufacturing process, by pushing a blank through a die, it is an advantage in a preferred embodiment to use the identical material for the projections and the rest of the medical tube.

In a further preferred embodiment said medical tube (10) is made of a material different to a material of said projections (20).

Thus, the kinking behaviour of the abrasive resistance can be enhanced. From a cross sectional point of view, there are possibilities of how the material of the projections can be different to the material of the rest of the medical tube. The shade and ratio of different materials in said projection can vary gradually.

Starting with a thin layer out of different material atop the projections, over to a smooth transmission of different materials, ending with solid projection out of one material, different to the material of the medical tube. Thus, a layer of different material can provide an enhanced abrasion resistance, whereas a solid projection out of different material provides additional stiffness and allows less torsion of the tube. Preferably materials as plastics, latex, glass or metal are used.

In a further preferred embodiment said projections (20) have different shapes.

This results in better guidance when inserting medical equipment with a non-circular cross sectional shape. These different shapes also result in different physical properties (e.g. stiffness, torsional stiffness, etc.).

In a further preferred embodiment said projections ) (20) have different size, meaning the variation in its dimension.

This comprises (in a cross sectional view) width and height and therewith the cross section area on the one hand and height variations along a longitudinal section view on the other hand, which results in different physical properties.

In a further preferred embodiment a dividing wall (31) between the first and the second lumen is 30 % to 120 % of the tube wall (13), meaning the average thickness.

Preferably the dividing wall is 50 %, more preferably 75 %, most preferably 100 % of the tube wall.

The dividing wall divides the first and second lumen from each other, prohibits mixing of bodily fluids and prevents collision of medical equipment and other tools when operating parallel in the medical tube. In a further preferred embodiment the number of lumen is two. This is the case in certain applications, where in surgery more than one measurement is taken at the same time. An embodiment therefore is an arterial pulse pressure measurement contemporaneous with a thermo dilution measurement. Here, one lumen is filled with blood and/or saline solutions and/or ringer's lactate, etc. whereas the other lumen contains the temperature sensor.

In a further preferred embodiment the medical tube (10) is a flexible tube, a medical tube, a diagnostic medical tube, a therapeutic medical tube, a cerebrovascular medical tube, an ultrasonic medical tube, a bypass, a synthetic tube, an infusion tube or a connecting tube.

In the figures, further preferred embodiments are illustrated. The figures show:

Fig.l a schematic view of a cross section of a medical tube with two lumen according to an embodiment of the present invention

Fig.2 a schematic view of a cross section of a medical tube with two lumen according to an embodiment of the present invention

Fig.3 a schematic view of a cross section cut-out of a medical tube according to another embodiment of the present invention; and

In Figure 1 a schematic view of a cross section of a medical tube according to another embodiment of the present invention is illustrated. Figure 1 shows a medical tube with two lumens 30.1 as first lumen and 30.2 as second lumen separated through a dividing wall 31. The second lumen 30.2 is a circle with a second inner surface 11.2 and a radius ri2=0,2mm. The first lumen 30.1 is provided with three projections 20.1, 20.2 and 20.3 forming three limitative points 51, 52, 53. Projections 20.1 and 20.2 in combination with projection 20.3 provide guidance for the indicated medical equipment 40 (illustrated with a dotted circle). Lumen 30.1 has a D-shaped form, wherein the bended line (parts of the inner surface)

11.1 has the radius ri1=0, 6mm and describes a segment of a circle. The segment of a circle is limited by the chord 14. Projection 20.3 is situated in the middle of the chord 14 and has the height of 0,05mm. The other two projections 20.1 and

20.2 are provided on the bended line (inner surface) of the first lumen and enclose an angle of 80 degrees and have the height of 0,09mm. The outer periphery 12 with the radius ro=0,86mm and diameter 12.1 encloses all those components. Furthermore ro-ril equals the thickness d of the tube wall 13. Radius ro is measured from the medical tube centre 15 to the outer periphery.

This embodiment is designed to divide two lumens. In this embodiment lumen 30.1 can be used for inserting a temperature sensor in order to perform a thermo delusion measurement and parallel lumen 30.2 can be used for pulse pressure measurement. Thus, two lumens 30.1 and 30.2 are foreseen, whereas lumen 30.1 provides the larger cross section area in order to enable passing of said medical equipment. The smaller lumen 30.2 is mainly used for carrying a temperature sensor, a pressure sensor or used for blood transport.

When using the Seldinger technique and inserting the medical tube into the human body, this medical tube 10 as shown in the figure glides over a guide wire, which passes through lumen 30.1. During this application the wire, with respective size, is held in guidance inside the medical tube by the projections 20.1, 20.2 and 20.3. The three points of support (limitative points) are the top of each projection, providing very low friction. Because of the guidance, which keeps the guide wire in a central position, the remaining cavities can be used, too (e.g. liquids can be pass). In addition, the projections not only provide low friction, but as well good guidance of the equipment inside the medical tube 10 and therefore avoid piercing through the tube wall 13 when passing turns and curves. All projections have rounded surfaces providing low friction and good guidance, when gliding a medical tool through the medical tube 10.

Additionally, higher abrasion resistance in rotational direction compared to other projection shapes (e.g. triangle, with pointy edges) is given. With the projections 20.1 and 20.2 also the medical equipment is kept at distance towards the tube wall 13, minimizing the risk of piercing.

The medical tube here shown finds its application in the field of catheters. When using said medical tube as a catheter tube, fluids of all kinds can pass lumen 30.2 of the tube. Then, for a trouble-free use it is mandatory that the medical tube provides certain qualities, for example non- kinking behaviours to disable tube-closure and enable throughput at all times. Additionally, an interior shape to avoid adherence of any particles is advantageous. When medical equipment is used to glide through the medical tube (the D-shaped first lumen), kinking behaviour of said tube is also objectionable, as it would damage the equipment in use and lead to complications during surgery. Wanted properties of the medical tube inside the first lumen are high friction resistance and a low friction coefficient. High torsional stiffness of the whole medical tube system is also appreciated, as additional friction of all kind inside the human body should be avoided in order to prevent irritation (of for example a vein's or artery's inside). In Figure 2 a schematic view of a cross section of a medical tube according to another embodiment of the present invention is illustrated. Figure 1 shows a medical tube with two lumens 30.1 as first lumen and 30.2 as second lumen separated through a dividing wall 31. The second lumen 30.2 is a circle with a second inner surface 11.2 and a radius ri2=0,2mm. The first lumen 30.1 is provided with four projections 20.1, 20.2, 20.3. and 20.4. Projections 20.1 and 20.2 in combination with projection 20.3 and 20.4 provide guidance for the indicated medical equipment 40 or guide wire 16

(illustrated with a dotted circle). Lumen 30.1 has a D-shaped form, wherein the bended line (parts of the inner surface) 11.1 has the radius ri1=0, 6mm and describes a segment of a circle. This segment of a circle is limited by the chord 14. Projections 20.3 and 20.4 are situated on the chord 14 and have the height of 0,1mm. Projections 20.3 and 20.4 have the same distance from the middle of the chord, which is 0,25mm. Projection 20.3 and 20.4 have a distance d=0,5mm to each other. The other two projections 20.1 and 20.2 are provided on the bended line (inner surface) of the first lumen and enclose an angle of 80 degrees and have the height of 0,09mm. The outer periphery 12 with the radius ro=0,86mm and diameter 12.1 encloses all those components. Furthermore ro-ril equals the thickness d of the tube wall 13. Radius ro is measured from the medical tube centre 15 to the outer periphery.

The difference to figure 1 is, that in figure two the guide wire 16 can have a smaller diameter 11.3 than in figure 1 without touching the tube wall 13 during application.

In figure 3 a schematic view of a cross section cut-out of a medical tube according to another embodiment of the present invention is illustrated. The figure shows a tube wall 13, described by an outer periphery 12 and an inside 11, providing a projection 20, whose height is to be defined and measured. The height h of the projection 20 is measured rectangularly between two parallel lines Ll and L2 setting limits to top and base of the projection. The two lines Ll and L2 are straight lines. Ll is defined as base line, described by intersection point Il and 12. Il and 12 are the intersection points of circle 14 with centre C and the boundary line of projection 20. Centre C is the geometric centre of a medical tube with circular or nearly circular outer periphery. L2 includes the farthest possible point P to Ll, being part of projection 20.

Reference numbers

10 Medical tube

11 Inside

11.1 First inner surface

11.2 Second inner surface

11.3 inner circle diameter

11.4 Elliptic segment or circular segment

11.5 Maximum inner circle

12 Outer periphery

12.1 Outside diameter of the medical tube

13 Tube wall (of the medical tube)

14 Chord

15 Centre point of medical tube

16 Guide wire

17 Minimum thickness of tube wall 13 20 Projection(s) 20.1, 20.2, 20.3, ...

30 Lumen(s) 30.1, 30.2, ...

31 Dividing wall (between different lumens) 40 Indicated medical equipment

C Medical tube centre (if outer periphery is circular) 14 Circle

11 Interception point 1

12 Interception point 2 Ll Base line

L2 Limiting top line of (20)

P Point included in (20), farthest point from Ll

51 Limitative point

52 Limitative point

53 Limitative point

Claims

1. Medical tube (10), having an outer periphery (12), a tube wall (13), a first lumen (30.1) with a first inner surface (11.1), a second lumen (30.2) with a second inner surface (11.2), wherein the lumens (30.1, 30.2) are separated by a dividing wall (31), characterized in that, the first lumen (30.1) has a D-shape in a cross sectional view to the axis (17) of the medical tube (10) and the first inner surface (11.1) of the first lumen (30.1) has at least one projection (20), thus defining a maximum inner circle (11.5) with an inner circle diameter (11.3) which touches at least three limitative points (51, 52, 53) of the first inner surface (11.1) of the first lumen (30.1).

2. Medical tube (10) according to claim 1, wherein the first inner surface (11.1) of the first lumen (30.1) has at least two projections (20.1 and 20.2)

3. Medical tube (10) according to claim 1 or 2, wherein the D-shape of the lumen comprises a circular segment or an elliptic segment (11.4) and a chord (14).

4. Medical tube (10) according to one of the preceding claims, wherein the cord (14) provides at least one projection (20), preferably provides at least two projections (20.3, 20.4).

5. Medical tube (10) according to one of the preceding claims, wherein the projections ) (20) have a shape and a position on the cord, that at least the three limitative points (51, 52, 53) the maximum inner circle (11.5) are situated at the projections.

6. Medical tube (10) according to one of the preceding claims, wherein the total number of projections (20) is three or four.

7. Medical tube (10) according to one of the preceding claims, wherein two of the projections (20.1, 20.2) provided on the first inner surface (11.1) include an angle of 120° +/- 30°, measured from a centre point (15) of the medical tube (10).

8. Medical tube (10) according to one of the preceding claims, having an outside diameter (12.1) wherein the ratio of the outside diameter (12.1) to the inner circle diameter (11.3) of the maximum inner circle (11.5) is 2 to 1.

9. Medical tube (10) according to one of the preceding claims, wherein the height of said projections (20) is 30 % to 200 % of a thickness (17) of said tube wall (13).

10. Medical tube (10) according to any of the preceding claims, wherein the shape of said projections (20.1, 20.2) is of a triangle, a trapezium or a segment of a circle.

11. Medical tube (10) according to any of the preceding claims, wherein the thickness of a dividing wall (31) between different lumens (30) is 80 % to 120 % of the tube wall (13) .

12. Medical tube (10) according to any of the preceding claims, wherein the medical tube (10) is a flexible tube, a medical tube, a diagnostic medical tube, a therapeutic medical tube, a cerebrovascular medical tube, an ultrasonic medical tube, an infusion tube or a connecting tube.