WO2008132660A1

WO2008132660A1 - Needle for mechanically assisted insertion

Info

Publication number: WO2008132660A1
Application number: PCT/IB2008/051551
Authority: WO
Inventors: Aleksey Kharin; Maarten Steinbuch; Tomas De Boer
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2007-04-25
Filing date: 2008-04-23
Publication date: 2008-11-06
Also published as: JP2010524623A

Abstract

The invention concerns a needle for mechanically assisted insertion of the needle into an object and, in particular, for automated insertion, comprising a cylindrical body (32), enclosing a channel (33), and a cutting (34) part at the exit of the channel (33), the cutting part (34) comprising at least one surface defining at least one bevel (35) and at least one transition edge (37) of the bevel, the cutting part (34) comprising at least one irregularity (39) on said surface, the irregularity (39) generating a change in the shape of a measured insertion resistance force profile of the needle into the object, in order to permit the detection of the position of the needle in the object during its insertion.

Description

Needle for mechanically assisted insertion

Field of the invention

The invention relates to a needle for mechanically assisted insertion into an object. The invention is particularly adapted to automated insertion.

Background of the invention

Insertion of a needle into a living body is a very common medical procedure. Often a needle is inserted to gather blood from a vessel, to inject a vaccine or into a silicone septum. The procedure is however often carried out manually notably into human bodies. Even though performed by trained medical staff, difficulties arise in about 5% of the insertion procedures and may result in multiple insertions or haematomas. In the end the medical staff is under extra pressure and patients under greater pain and discomfort. Mechanically assisted or fully automated needle insertion is expected to have a number of benefits. The biggest challenge in a mechanically assisted insertion procedure or in an automated insertion procedure is the control of the advancement of the needle insertion.

In the prior art, it has been proposed to monitor the insertion of a needle into a vessel by measuring an insertion resistance force profile of the needle into the vessel, in order to deduce the position of the needle as a function of the resistance force measured on the needle while it is inserted in the vessel. An insertion resistance force profile of a needle contains information on the position of the needle within the vessel since the different parts of the needle, having different shapes, do not generate the same resistance by the vessel while being inserted therein. The decision to stop the needle advancement is based on a change of the slope of the resistance force profile.

Fig. Ia is a needle 1 of the prior art. Needle 1 comprises cylindrical body 2 that encloses a channel 3 and, adjacent to cylindrical body 2, a cutting part 4 at the exit of channel 3. Cutting part 4 comprises surfaces defining a plurality of bevels: two front bevels 5a, 6a and two rear bevels 5b, 6b. Front bevels 5a, 6a join at needle tip 4' (or needle point 4'), which forms a sharp apex adapted to penetrate into an object. Considered as a whole, the cutting part 4 is beveled with a certain angle (herein approximately 60°) relatively to a plane transverse to the axis of cylindrical body 2. The angle permits a progressive insertion of the needle 1. The front bevels 5a, 6a join the rear bevels 5b, 6b at transition edges 5c, 6c and the rear bevels 5b, 6b meet near cylindrical body 2, which they join at a common transition edge 7. Fig. Ib is a graph representing the insertion resistance force exerted on the needle 1 of Fig. Ia by a 6mm diameter vessel, as a function of the depth of insertion of the needle 1 in the vessel. The force profile comprises a first peak 8a corresponding to the insertion of the needle point 4' and the front bevels 5a, 6a into the wall of the vessel. The needle is inserted into the vessel when the needle cutting part 4 breaks through the vessel wall. In the decreasing slope of the first peak 8a, the force profile comprises a second small peak 8b corresponding to the passage of the first transition edges 5c, 6c of the front and rear bevels (5a, 5b), (6a, 6b) through the wall of the vessel. The force profile then again decreases and comprises a third small peak 8c which corresponds to the passage of the transition edge 7 (situated between the rear bevels 5b, 6b and the cylindrical body 2 of the needle 1) through the wall of the vessel. The force profile then again decreases and comprises, at 6mm of insertion depth, a fourth peak 8d corresponding to the breaking of the needle cutting part 4 through the opposite wall of the vessel.

The prior art uses the above described force profile in order to control the insertion of a needle within a blood vessel of a person. However, this profile may not be reliable and accurate enough for monitoring the insertion in small vessels, which is precisely the type of vessels where the monitoring is the most important. Indeed, if the first peak 8a is used as a position criterion, only a small portion of needle 1 has been inserted and, notably, channel 3 is not yet within the vessel. Besides, the second and third peaks are too small and thus too difficult to recognize to be used with high reliability. Finally, when the fourth peak is detected, the needle has already pierced the opposite wall of the vessel, which is precisely what should be avoided thanks to the monitoring. Moreover, due to the deformation of the vessel, the fourth peak could not even be used to detect the position of the needle when it touches the opposite wall; indeed, due to the vessel deformation, the part of the needle that has been inserted through the first wall at the moment it penetrates the opposite wall depends, not only on the distance between those two walls, but also on the deformation of the vessel. Therefore, the force profile of the insertion of a needle into an object is not adapted to help monitoring the mechanically assisted or automated insertion of a needle.

It is even less adapted if the depth at which the needle should be inserted is small, notably if it is not much greater, or even smaller, to the length of the cutting part of the needle.

Summary of the invention

It is therefore an object of the present invention to provide a device for an accurate monitoring of the mechanically assisted or automated insertion of a needle into an object.

In accordance with the present invention there is provided a needle A needle adapted for a mechanically assisted insertion of the needle into an object, the needle comprising a cylindrical body enclosing a channel, and a cutting part at the exit of the channel, the cutting part comprising one planar bevel and at least one surface irregularity causing a peak of the insertion resistance force of the needle into the object.

.A measured insertion resistance force of a needle into an object is the insertion resistance force on the needle as a function of the insertion depth of the needle.

A graph could represent the reaction force exerted by the object on the needle, as a function of the portion of the needle which has been inserted therein. A peak in the shape of the force profile will be understood as a sudden change in the slope of a curve representing the force, resulting in a curve which exhibits a particular shape (or feature) at that point.

The surface of the cutting part of the needle of the invention defines an irregularity different from the planar bevel. The irregularity is neither a bevel nor a transition edge. As a consequence, the shape (or slope) of the insertion resistance force profile comprises a change, for instance a further peak, which is due to the change in the resistance force when the irregularity is inserted into the object. Since the irregularity differs in shape from the bevels and transition edges, the induced change in the shape of the force profile is recognizable from the traditional peaks, described above, related to the insertion of the bevels or transition edges. This change in shape appears at the insertion position of the irregularity and therefore represents a signal meaning that the needle has been inserted up to this irregularity. Based on this information, the mechanically assisted needle insertion method is improved, since the particular feature in the shape of the force profile is much more accurate information than the peaks in the shape of the force profiles of the prior art. Notably, the information related to the irregularity could be used to stop the needle insertion at that point. Depending on how deep a needle should be inserted, a needle with an irregularity placed at the corresponding position on the surface of the cutting part of the needle can therefore be used.

Thanks to the invention, a mechanically assisted needle insertion method may therefore be much more accurate and precise. The invention is particularly surprising compared to the prior art, notably in the sense that the whole prior art aims at reducing the pain of the patient to whom a needle is inserted, while with the invention, the addition of an irregularity, which is further to the bevels and transition edges, may actually provoke an increased amount of pain to the patient. However, this potential temporary increased pain results in an advantage, namely that mechanically assisted insertion of a needle may be performed, which is more secure than manual insertion and will notably permit to avoid problems, such as multiple insertions or haematomas, which occur when manual insertions are missed.

According to an embodiment, the change in the shape of the force profile comprises at least one peak.

According to an embodiment, the irregularity is adapted to generate a peak with an abrupt change in the slope of the force profile, compared to peaks generated by the bevels and transition edges.

According to an embodiment, the irregularity comprises at least one surface extending generally transverse to the axis of the needle.

According to an embodiment, the irregularity is of the protrusion type or of the recess type.

According to an embodiment, the irregularity comprises at least one of the following: a groove, a rib, a notch and a bump. According to an embodiment, the surface of the cutting part defining a plurality of bevels and transition edges, the irregularity is positioned so as to generate an additional peak between two peaks corresponding to transition edges of the cutting surface.

According to an embodiment, the cutting part defining a channel aperture and a needle point, the irregularity is located at the proximity of the end of the channel aperture, opposite the needle point.

In accordance with the present invention there is also provided a device for the automated insertion of the needle presented above into an object, the device comprising means for driving the needle into the object, means for measuring an insertion resistance force profile of the needle into the object and means for controlling the movement of the driving means as a function of the force on the needle.

In accordance with the present invention there is also provided a device for the mechanically assisted insertion of the needle presented above into an object, the device comprising means for holding the needle while it is inserted into the object, means for measuring an insertion resistance force profile of the needle into the object, means for recognizing a change in the force profile and means for sending a signal when such a change is recognized.

These and other aspects of the invention will be more apparent from the following description with reference to the attached drawings.

Brief description of the drawings

- Fig. Ia is a picture of a needle of the prior art;

- Fig. Ib is an insertion resistance force profile measured during the insertion of the needle of Fig. Ia into a 6mm diameter blood vessel;

- Fig. 2A is a perspective front view of a needle according to a first embodiment of the invention;

- Fig. 2B is a perspective side view of a needle according to a second embodiment of the invention;

- Fig. 2C is an insertion resistance force profile measured during the insertion of the needle of Fig. 2B into a blood vessel; - Fig. 3 is a perspective front view of a needle according to a third embodiment of the invention; - Fig. 4a is a perspective side view of a needle according to a fourth embodiment of the invention;

- Fig. 4b is an insertion resistance force profile measured during the insertion of the needle of Fig. 4a into a blood vessel; - Fig. 5a is a perspective side view of a needle according to a fifth embodiment of the invention;

- Fig. 5b is an insertion resistance force profile measured during the insertion of the needle of Fig. 5a into a blood vessel;

- Fig. 6a is a perspective side view of a needle according to a sixth embodiment of the invention and

- Fig. 6b is an insertion resistance force profile measured during the insertion of the needle of Fig. 6a into a blood vessel.

Detailed description of the embodiments With reference to Fig. 2A, a needle 21 according to a first embodiment comprises a cylindrical body 22 enclosing a channel 23. In this embodiment body 22 is tubular. At one end of channel 23, needle 21 comprises a cutting part 24, whose walls define an exit aperture of the channel 23. The cutting part 24 may be a few millimeters long, for instance, 3mm long. The other end of channel 23 is adapted to be connected to a syringe, for instance. The channel 23 is adapted for fluid conduction. Needle 21 may be a venipuncture needle adapted to draw in and collect blood from a blood vessel. If the needle is an injection needle, it is adapted to inject a fluid, for instance a vaccine, from the syringe into a blood vessel or a muscle. Cutting part 24 of needle 21 may also be used for piercing an object, such as for instance an elastomeric recipient containing a fluid.

Cutting part 24 of needle 21 comprises a surface defining here a unique bevel 25. Bevel 25 defines on one side a needle tip 24' which is not a sharp point but a rather curved point 24'. Point 24' defines a cutting surface which permits insertion of the needle into an object or living body. Cutting part 24 is beveled with a certain angle (herein approximately 60°) relatively to a plane transverse to the axis 22' of the cylindrical body 22. The angle permits to progressively insert needle 1. Bevel 25 joins the cylindrical body 22 at a transition edge 27 situated on the cutting part 24 opposite to needle tip 24'.

The surface of cutting part 24 comprises an irregularity 29. In Fig.2A, irregularity 29 is a groove. Groove 29 is a rectilinear, of a cylindrical shape and perpendicular to the axis 22' of needle body 22. Groove 29 starts on the beveled surface of the cutting part 24 within the channel aperture of needle 21 and ends at the edge 23' at the end of the channel aperture and close to the transition edge 27 of the cylindrical body 22 opposite to the needle point 24'.

Groove 29 introduces a sudden change, here a sharp peak, in a measured insertion resistance force profile of needle 21. Detection of this peak during an automated needle insertion informs the practitioner that needle 21 has been inserted as far as the groove 29. This further indicates that the whole exit aperture of channel 23 has been inserted. The automated insertion may be stopped.

Incidentally, documents in the prior art, such as US5, 752,942, disclose needles comprising a cutting part with bevels and transition edges between those bevels. However, those bevels and transition edges cannot be considered as irregularities in the sense of the present invention, notably since those bevels and transition edges do not fulfil the function of the irregularity of the invention, which is to generate a further peak in a measured insertion resistance force profile so as to permit monitoring of the needle insertion. As recited in US 5,752,942, the documents of the prior art are aimed at reducing the height of the transition edges so as to result in a more continuous beveled surface; at the contrary, the present invention provides for an irregularity in the beveled surface, that is to say, a discontinuous beveled surface, since the irregularity defines a discontinuity. Fig. 2B is another exemplary embodiment of a needle 2 IB of the invention.

Needle 21B comprises a plurality of bevels alike needle 1 of Fig. 1. Needle 21B comprises cylindrical body 22B, enclosing a channel 23B. Needle 21B further comprises cutting part 24B at one end of channel 23B and the walls of cutting part 24B define an exit aperture of channel 23B. Cutting part 24B comprises surfaces defining a plurality of bevels: two front bevels 25Ba, 26Ba and two rear bevels 25Bb, 26Bb. Front bevels 25Ba, 26Ba join at a needle tip, not shown, which forms a sharp apex adapted to penetrate into an object. Considered as a whole, the cutting part 24B is beveled with a certain angle (herein approximately 60°) relatively to a plane transverse to the axis 22'B of the cylindrical body 22B. The angle permits a progressive insertion of needle 21B. The front bevels 25Ba, 26Ba join the rear bevels 25Bb, 26Bb at transition edges 25Bc, 26Bc, the rear bevels 25Bb, 26Bb meeting near the cylindrical body 22B, which they join at a common transition edge 27B situated on the cutting part 24B opposite to the needle point.

The surface of the cutting part 24B comprises an irregularity 29B. Irregularity 29B is a rectilinear groove of cylindrical shape perpendicular to the axis 22'B of needle body 22B. Groove 29B starts on the beveled surface of the cutting part 24B within the channel aperture of the needle 2 IB. Groove 29B ends at the upper edge 23 'B which forms the end of the channel aperture, at the proximity of the transition edge 27B to the cylindrical body 22B opposite to the needle point.

Irregularity 29B introduces a recognizable change in a measured insertion resistance force profile. Such a profile is represented on the graph of Fig. 2C, comprising in ordinate the resistance force F induced by the blood vessel on the needle 2 IB and in abscissa the length x of the needle 2 IB which has been inserted into the vessel. The time t of insertion may also be shown instead of length x if the insertion is done at a constant speed.

The force profile exhibits a first peak 28a corresponding to the insertion of the needle point and the front bevels 25Ba, 26Ba into the wall of the vessel, when the needle cutting part 24B breaks through the vessel wall. In the decreasing slope of the first peak 28a, the force profile comprises a second smaller peak 28b corresponding to the passage of the first transition edges 25Bc, 26Bc of the front and rear bevels (25Ba, 25Bb), (26Ba, 26Bb) through the wall of the vessel. The force profile then again decreases and comprises a change 28c in its shape (slope), which is a particular feature of the force profile which corresponds to the insertion of groove 29B through the wall of the blood vessel. This change, compared to the profile of a needle of the prior art without any irregularity, has been represented in dashed line on the graph, the curve of a needle without the irregularity as proposed in the invention having been let in full line. The change 28c in the curve of the force profile comprises herein two peaks: a first peak 28c' which represents a drop of force compared to the normal curve and a second peak 28c" which represents an increase in force compared to the normal curve. The first peak 28c' is due to the change of slope of the needle rear bevels 25Bb, 26Bb, where the slope is such that, compared to the general slope of the bevels 25Bb, 26Bb, the cutting surface is oriented in the direction of the inside of the needle 2 IB or in the direction of its axis 22'B. The second upper peak 28c" is due to the change of slope where the cutting surface is oriented towards the exterior of the needle 2 IB, with a slope higher than the general slope of the bevels 25Bb, 26Bb.

The force profile comprises a fifth small peak 28d which corresponds to the passage of the transition edge 27B situated between the rear bevels 25Bb, 26Bb and the cylindrical body 22B of the needle 21B through the wall of the vessel. Therefore, the cutting surface 24B of the needle 2 IB has been engineered, with the irregularity 29B, so as to modify the needle insertion resistance force profile, thus the needle 21B exhibits a recognizable change 28c in the shape of its force profile while penetrating into an object, in particular into a layered tissue such as skin. This permits to have accurate information on the position of the needle within the object and to monitor its insertion until it needs be stopped. The irregularity 29B on the needle 2 IB is therefore a discrete mark reporting the needle position within the object, which is detected with the slope of the force profile changing.

With reference to Fig. 3, a needle 31 according to a third embodiment comprises a cylindrical body 32, enclosing a channel 33, and a cutting part 34, the walls of which define an exit aperture of the channel 33. The cutting part 34 comprises a surface defining a unique bevel 35, which defines a needle tip 34'. The bevel 35 joins the cylindrical body 32 at a transition edge 37 situated, on the cutting part 34, opposite the needle tip 34'. The surface of the cutting part 34 comprises an irregularity 39 which, in the embodiment of Fig. 3, is a rib 39. The rib 39 is a rectilinear rib 39, of a cylindrical shape, perpendicular to the axis 32' of the needle body 32. The rib 39 is formed so as to extend close to the extremity of the channel aperture, opposite the needle tip 34'. The rib 39 generates an extra peak on a measured insertion resistance force profile of the needle 31.

With reference to Fig. 4a, a needle 41 according to a fourth embodiment comprises a cylindrical body 42, enclosing a channel 43, and a cutting part 44, the walls of which define an exit aperture of the channel 43. The cutting part 44 comprises surfaces defining a plurality of bevels; the needle described comprises two front bevels 45a, 46a and two rear bevels 45b, 46b, as in the needle 1 described with reference to Fig. Ia. The front bevels 45a, 46a join at a needle tip (or needle point), not shown. Considered as a whole, the cutting part 44 is beveled with a certain angle (herein approximately 60°) relatively to a plane transverse to the axis 42' of the cylindrical body 42, in order to authorize a progressive insertion of the needle 41. The front bevels 45a, 46a join the rear bevels 45b, 46b at transition edges 45c, 46c, the rear bevels 45b, 46b meeting near the cylindrical body 42, which they join at a common transition edge 47 situated, on the cutting part 44, opposite the needle point.

The surface of the cutting part 44 comprises an irregularity 49 which, in the embodiment of Fig. 4a, is a rib 49. The rib 49 is a rectilinear rib 49, of a cylindrical shape, perpendicular to the axis 42' of the needle body 42. The rib 49 is formed so as to end before the edge 43' forming the end of the channel exit aperture, which is opposite, on the walls of the cutting surface 44 defining this exit, to the needle point. The rib 49 is in fact a discontinuous rib 49, since it extends on a portion of the cutting part 44 where the surfaces defining the bevels 45a, 45b, 46a, 46b, needle point and transition edges 45 c, 46c, 47 are separated by the channel aperture; the rib 49 comprises two portions of ribs, each on a rear bevel 45b, 46b, on both sides of the channel aperture.

Depending on how far the rib 49 is from the edge 43' defining the end of the channel aperture, the needle 41 of Fig. 4a may be used in several automated methods. According to a first embodiment, the rib 49 is situated at said edge 43' and permits to perform a method where the needle insertion is stopped when the whole channel aperture has been inserted within the vessel (in such a case, the insertion may be stopped just after the peak generated by the rib 49 has appeared). According to a second embodiment, the rib 49 is positioned, on the cutting part 44, closer to the needle point, at a distance from said edge 43' and permits to perform a method where the needle insertion is stopped before the whole channel aperture has been inserted, for instance because the diameter of the blood vessel where the needle should be inserted is smaller than the length of the cutting part 44; for instance, a 3mm long cutting part 44 could be inserted into a 2mm diameter vessel, the insertion being stopped before 2mm of the cutting part 44 have been inserted.

The insertion resistance force profile of the needle 41 of the fourth embodiment is represented on the graph of Fig. 4b with, again, the reaction force F in ordinate and the inserted length x (or time t in case of constant speed) in abscissa. The force profile comprises a first peak 48a corresponding to the insertion of the needle point and the front bevels 45a, 46a into the wall of the vessel. In the decreasing slope of the first peak 48a, the force profile comprises a second peak 48b, corresponding to the passage of the first transition edges 45c, 46c of the front and rear bevels (45a, 45b), (46a, 46b) through the wall of the vessel. The force profile then again decreases and comprises a change 48c in its shape (or slope), represented in dashed lines, which is a particular feature of the force profile which corresponds to the insertion of the rib 49 through the wall of the blood vessel. The change 48c in the curve of the force profile again comprises two peaks: a first peak 48c' which represents a raise of force, compared to the normal curve, and corresponding to the raise of slope of the surface at the beginning of the rib 49, and a second peak 28c" which represents a drop of force, compared to the normal curve, and corresponding to the decrease of slope of the surface at the end of the rib 49. The force profile comprises a fifth tiny peak 48d which corresponds to the passage of the transition edge 47 (situated between the rear bevels 45b, 46b and the cylindrical body 42 of the needle 41) through the wall of the vessel.

The sharp extra peaks 48c', 48c", measured in an insertion resistance force profile of the needle 41 during the insertion of the needle 41 into a vessel can be directly used by an automated needle insertion instrument to monitor the needle insertion and, notably, to stop it.

With reference to Fig. 5a, a needle 51 according to a fifth embodiment comprises a cylindrical body 52, with an axis 52', enclosing a channel 53, and a cutting part 54, the walls of which define an exit aperture of the channel 53. The cutting part 54 comprises surfaces defining a plurality of bevels; the needle described comprises two front bevels 55a, 56a and two rear bevels 55b, 56b. The front bevels 55a, 56a join at a needle tip (or needle point), not shown. The front bevels 55a, 56a join the rear bevels 55b, 56b at transition edges 55c, 56c, the rear bevels 55b, 56b meeting near the cylindrical body 52, which they join at a common transition edge 57 situated, on the cutting part 54, opposite the needle point. The surface of the cutting part 54 comprises an irregularity 59 which, in the embodiment of Fig. 5a, is a notch 59. The notch 59 has the shape of a portion of sphere; it could also be of a conical shape, for instance. The notch 59 is formed on the wall corresponding to one of the rear bevels 56b; the notch 59 is therefore formed on only one side of the exit aperture of the channel 53.

In the described embodiment, the notch 59 is provided on an exterior edge of the wall of the bevel 56b it is formed on, which provokes a more noticeable change in the force profile.

The insertion resistance force profile of the needle 51 of the fifth embodiment is represented on the graph of Fig. 5b with, again, the force F in ordinate and the inserted length x (or time t in case of constant speed) in abscissa. The force profile comprises a first peak 58a corresponding to the insertion of the needle point and the front bevels 55a, 56a into the wall of the vessel, a second peak 58b, corresponding to the passage of the first transition edges 55c, 56c of the front and rear bevels (55a, 55b), (56a, 56b) through the wall of the vessel, a change 58c in its shape, represented in dashed lines, which is a particular feature of the force profile which corresponds to the insertion of the notch 59 through the wall of the blood vessel, and a last peak 58d which corresponds to the passage of the transition edge 57 (situated between the rear bevels 55b, 56b and the cylindrical body 52 of the needle 51) through the wall of the vessel.

Since the notch 59 is an irregularity of the recess type, the change 58c in the curve of the force profile comprises a first dropping peak 58c' and a second raising peak 58c". This change in shape forms a marker, for an automated insertion instrument, which permits to know that the needle 51 has been inserted up to the notch 59.

With reference to Fig. 6a, a needle 61 according to a sixth embodiment comprises a cylindrical body 62, with an axis 62', enclosing a channel 63, and a cutting part 64, the walls of which define an exit aperture of the channel 63. The cutting part 64 comprises a surface defining a plurality of bevels; the needle described comprises two front bevels, only one 66a is shown, and two rear bevels 65b, 66b. The front bevels 66a join at a needle tip (or needle point), not shown. The front bevels 66a join the rear bevels 65b, 66b at transition edges, only one 66c is shown, the rear bevels 65b, 66b meeting near the cylindrical body 62, which they join at a common transition edge 67 situated, on the cutting part 64, opposite the needle point. The surface of the cutting part 64 comprises an irregularity 69 which, in the embodiment of Fig. 6a, is a bump (or dome) 69, of an ovoid shape, disposed transversally to the axis 62' of the needle 61. The bump 69 is formed at the position of the edge 63' forming the end of the channel aperture, opposite the needle point.

The insertion resistance force profile of the needle 61 of the sixth embodiment is represented on the graph of Fig. 6b with, again, the force F in ordinate and the inserted length x (or time t in case of constant speed) in abscissa. The force profile comprises a first peak 68a corresponding to the insertion of the needle point and the front bevels 65a, 66a into the wall of the vessel, a second peak 68b, corresponding to the passage of the first transition edges 65c, 66c of the front and rear bevels (65a, 65b), (66a, 66b) through the wall of the vessel, a change 68c in its shape, represented in dashed lines, which is a particular feature of the force profile which corresponds to the insertion of the bump 69 through the wall of the blood vessel, and a last peak 68d which corresponds to the passage of the transition edge 67 (situated between the rear bevels 65b, 66b and the cylindrical body 62 of the needle 61) through the wall of the vessel.

Since the bump 69 is an irregularity of the protrusion type, the change 68c in the curve of the force profile comprises a first raising peak 68c' and a second dropping peak 68c". This change in shape 68c can be used for needle insertion monitoring in an automated insertion procedure.

While the invention has been illustrated and described in details in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

In particular, the shape of the irregularity may be varied. The person skilled in the art shall engineer a particular shape corresponding to a change in the force profile he wants to obtain. In other words, the change in the force profile, which permits the detection of the position of the needle, may be engineered by engineering the shape of the irregularity. As a consequence, very distinctive force profile shapes can be obtained, that will make the recognition process of the change much easier and more reliable.

The person skilled in the art shall also choose the dimensions of the irregularity. Basically, the bigger the size of the irregularity, the bigger the change in the force profile. Therefore, the choice of the size of the irregularity will be the result of a compromise between the desired shape and visibility of the change in the shape of the force profile, on the one hand, and the pain experienced by the patient, on the other hand.

Also, when the irregularity is a rib or a groove, its shape could be rectangular instead of cylindrical. The irregularity may be placed near the end of the channel exit aperture, so as to permit detection of the end of the insertion of this channel aperture. According to another embodiment, the irregularity may be positioned before the end of the channel aperture, in particular if the length of the cutting part of the needle is longer than the depth at which the needle should be inserted, therefore permitting to stop the needle insertion at the desired depth.

According to an embodiment, the needle cutting surface comprises a plurality of irregularities, therefore generating a plurality of changes (for instance, peaks) in an insertion resistance force profile of the needle. The plurality of irregularities can be of the same shape or of different shapes. This permits to have a plurality of position information, therefore permitting a more continuous monitoring of the needle insertion and/or the use of one type of needle in several possible applications, in which the needle should be inserted at different depths.

According to an embodiment, the irregularity is of the protrusion type, generating a feature in the force profile comprising two peaks, a raising peak and a dropping peak. According to an embodiment, the irregularity is of the recess type, generating a feature in the force profile comprising two peaks, a dropping peak and a raising peak.

Whatever the shape of the needle, whatever the shape of the irregularity, the needle of the invention may be used with an automated insertion device. Such a device may comprise driving means, for driving the needle into the object, means for measuring the reaction (resistance) force on the needle while it is inserted, and a servo- mechanism which permits to control the movement of the driving means as a function of the resistance force on the needle. The servo-mechanism may be controlled thanks to data containing the results of a measured insertion resistance force profile of a needle of the same type inserted in an object of the same type as the one the needle has to be inserted in. During an insertion process, the insertion resistance force should be measured in real time, during insertion of the needle. When the change in the force profile - corresponding to the irregularity - is detected, the insertion is stopped.

The needle of the invention may also be used with a system for assisting manual insertion. Such a system may be considered as partly automated, since the driving means are the hand (and force) of an operator. Such a system may comprise means for holding the needle, means for measuring the reaction force on the needle while it is inserted, means (calculation unit, controller) for recognizing a change in the force profile corresponding to the irregularity and means for sending a signal when such a change is recognized. Based on that signal, the operator of the mechanical assistance insertion system will stop the insertion. The signal may be a red light lighting.

According to an embodiment, the irregularity is arranged to generate a peak with an abrupt change in the slope of the force profile, compared to the peaks generated by the bevels and transition edges. In particular, the irregularity comprises a least one surface extending generally transverse to the axis of the needle, so as to induce a more recognizable sharp peak (and, incidentally, more pain on the patient if the needle is inserted within a human body). This is the case of the irregularities described with reference to Fig. 2A to Fig. 6a, where the irregularities each comprise such a transverse surface: the grooves 29, 29B of the embodiments of Fig. 2A and 2B extend transversally to the axis of the needle and therefore exhibit such a surface, the ribs 39, 49 of the embodiments of Fig. 3a and 4a extend transversally to the axis of the needle and therefore exhibit such a surface, the notch 59 of the embodiment of Fig. 5a is rounded or conical and therefore exhibit such a surface, and the bump 69 of the embodiment of Fig. 6a is ovoid, with its main dimension transverse to the axis of the needle, and therefore exhibit such a surface. According to an embodiment, the irregularity is positioned so as to generate an additional peak between two classical peaks corresponding to transition edges of the cutting surface; therefore, compared to a known insertion resistance force profile, the force profile of the needle with the irregularity comprises a peak that is easily recognizable. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1- A needle adapted for a mechanically assisted insertion of the needle into an object, the needle comprising: a cylindrical body (22) enclosing a channel (23), and a cutting part (24) at the exit of the channel, the cutting part comprising one planar bevel (25) and at least one surface irregularity (29) causing a peak of the insertion resistance force of the needle into the object.

2- A needle according to claim 1, wherein the irregularity (29) is adapted to generate a peak ((28c', 28c) with a more abrupt change in a slope of an insertion resistance force profile when the needle is inserted into the object than peaks generated by the bevel.

3- A needle according to claim 1, wherein the irregularity (29,) comprises at least one surface extending generally transverse to the axis of the needle.

4- A needle according to claim 1, wherein the irregularity (29) is of the protrusion type or of the recess type.

5- A needle according to claim 4, wherein the irregularity comprises at least one of the following: a groove (29, 29B), a rib (39, 49), a notch (59) and a bump (69).

6- A needle according to claim 1 wherein, the surface of the cutting part (24,) defines a plurality of bevels and transition edges, the irregularity (29) is positioned so as to generate an additional peak between two peaks corresponding to transition edges of the cutting surface.

7- A needle according to claim 1 wherein, the cutting part (24) defines a channel aperture and a needle point (24'), the irregularity (29) is located at the proximity of the end of the channel aperture, opposite to the needle point (24'). 8- Device for the insertion of the needle of claim 1 into an object, the device comprising means for driving the needle into the object, means for measuring an insertion resistance force profile of the needle into the object and means for controlling the movement of the driving means as a function of the force on the needle.