Driving unit for sampling devices

Abstract: The present invention briefly refers to a driving unit (1) for a device for tissue-sampling. The device comprises in addition to the driving unit a needle unit comprising a hollow outer needle (7a) and slidably disposed therein an inner needle (7b), the driving unit (1) being used to propel the needles (7a, 7b). The driving unit comprises a driving device for each needle and each driving device in turn comprises a spring mechanism adapted to be pre-tensioned. The driving unit in addition comprises an inner guide sleeve (3) containing two successive needle holders (4a, 4b) adapted to be shifted in relation to each other in the longitudinal direction of the sleeve and adapted to be pre-tensioned in the same direction for propelling the needles (7a, 7b) with the aid of one spring (5a, 5b) each and which are provided with releasable locking means (33a, 33b). A manual triggering device (6) is provided for releasing the one needle holder (4b) which in turn is adapted during the final phase of its propulsion to release the other needle holder (4a). A tensioning sleeve (2) which rotatably surrounds the guide sleeve (3) is provided with cam surfaces cooperating with the needle holders (4a, 4b) to pre­ tension them against the spring force.

Description: The present invention relates to devices for tissue sampling by so-called coarse-needle puncture in which a driving unit is used to drive the needle unit used for such a sampling. Specifically the invention refers to a novel driving unit for such a sampling device. Recently, it has become more common to take samples of inner tissue of man and animals, so-called biopsy, in order to diagnose various diseases such as cancer. The reason for this development is, on the one hand, that is is a reliable diagnosing method and, on the other hand, that sampling devices have been developed which are easy to use even for physicians who are not specialized on this sampling field. A prior-art sampling device of this type is described in the Swedish patent application No. 8600755-6 (corresponding to EP-A-238 461) where also the sampling procedure proper is described. The driving unit according to this invention is thus intended to be used to drive a needle unit and comprises a pair of springs which together with various guiding, locking, and triggering mechanisms are enclosed in a little box which also forms the handle of the sampling device. All the details in the box proper are made of corosion-free material of high quality, for example rustless steel. This box with its contents is impracticle for the reason that it is complicated and heavy, the latter factor causing the physician to become tired when carrying the instrument. Due to the fact that the device is complicated and contains comparatively expensive material the whole construction becomes expensive. This driving unit, however, may be sterilized and reused practically without limitations. However, there has been a demand for a sampling device of the above-indicated type that would be so cheap and simple as to be considered as a one-time sampler even if it might be used a few times prior to been discarded. The needle unit has previously been of the single-use type but when several samples are to be taken from the same patient both the needle unit and the driving unit may be used several times. Moreover, the demand has been noted that the sampling device should have low weight in order not to stress the hand of the sampler, should have an exceptable ergonomic shape and should offer no difficulties in connection with tensioning the springs in the driving unit. It is the purpose of the present invention to eliminate the drawbacks inherent in prior-art driving units and to fulfil the above-mentioned requirements. This purpose is achieved by means of a driving unit of the type indicated in the claims from which the specific characteristic features of the invention also will appear. Hereafter, the invention will be described in detail by reference to the attached drawings, in which FIGURE 1 is a side view of a sleeve forming the outer wall of the driving unit, FIGURE 2 is an end view of the sleeve shown in Fig. 1 seen in the direction of the arrows II-II, FIGURE 3 is a central longitudinal section of the sleeve shown in Figs. 1 and 2, FIGURE 4 is a flattened view of the sleeve shown in Figs. 1 to 3. FIGURE 5 is a side view of one of the needle holders with the needle shown with reduced length, it being understood that the outer needle holder has a substantially corresponding shape, FIGURE 6 is an end view of the end opposite to the needle of the needle holder shown in Fig. 5, FIGURE 7 is a side view of one of the guide sleeve composed of two halves, FIGURE 8 is a plan view from the concave side of the sleeve half shown in Fig. 7, FIGURE 9 is a section of the driving unit according to the invention in the released condition, and FIGURE 10 is a section corresponding to Fig. 9 but showing the portions in their pre-tensioned condition. A sampling device for biopsy purposes consists in this case of a needle unit and a driving unit combined in one unit. As mentioned initially, the needle unit and the sampling procedure are previously known and will therefore not be described in detail. The driving unit 1 comprises an outer tensioning sleeve 2 (Figs. 1 to 4), an internal guide sleeve 3 (Figs. 7 and 8), two needle holders 4 (Figs. 5 and 6), two driving springs 5 and a triggering knob 6 (Figs. 9 and 10). Attached within the one needle holder 4a is a tubular needle 7a whereas attached to the other needle holder 4b is a solid needle 7b having a cavity (not shown) for receiving a tissue sample, said latter needle 7b extending slidably through the tubular needle 7a. In Fig. 1 there is shown the outer sleeve or tensioning sleeve 2 forming the outer wall of the driving unit. As appears from Fig. 2, this sleeve is one substantially circular cross-section but has step-wise diminishing diameter. At its narrow end it carries a set of tongues 10, the free outer ends of which are radially pre-tensioned in an inward direction. The function of these tongues will be described later. The steps between the various diameters form cam surfaces, a rear cam surface 11 and a forward cam surface 12 extending radially into the sleeve. In the embodiment shown these cam surfaces 11, 12 are double which means that the cam surfaces 11, 12 are symmetrically repeated twice on the circumference. The shape and function of the cam surfaces 11, 12 will be described further down. The inner sleeve or guide sleeve 3 comprises two identical halves 13 which may be put together in a conventional way with the aid of pins and holes to form a unit of substantially cylindrical shape and circular cross section. At one end the guide sleeve 3 has a handle 14 and at the other end an axially directed hole 15 through which the needles 7a, 7b are to extend and which also forms a guide for these needles, and at the same end a radially inwardly extending circular groove 16 adapted to receive the tongues 10 of the tensioning sleeve 2. On the handle 14 a circular depression 17 is provided facing in an inward direction and adapted to be inserted into the tensioning sleeve 2 when the unit is assembled. The guide sleeve also has two circular flanges 18, 19 adapted to abut against the inner surface of the tensioning sleeve 2, and two pairs of axially extending guide grooves 20, 21 in diametrically opposed positions and extending through the wall of the guide sleeve 3. Within the guide sleeve 3 there is provided a circular shoulder 22 at the needle end forming an abutment for the forward needle holder 4a, an intermediate circular shoulder 23 forming, on the one hand, an abutment for the rear needle holder 4b and, on the other hand, a seat for the driving spring 5a for the forward needle holder 4a, and a rear circular shoulder 24 forming a seat for the driving spring 5b for the rear needle holder 4b. Both the rear shoulder 24 and the intermediate shoulder 23 also form parts of the locking mechanism during loading or tensioning of the driving unit of the sampling device, in particular if the driving springs 5a and 5b are compressed. Within the handle 14 there are in addition provided two opposite axially extending grooves 25 coacting with grooves or recesses 26 in the tensioning sleeve 2 to prevent the sampling device from being triggered except in one definite position, as well as guides for the triggering knob 6. As appears from Figs. 5 and 6, the needle holders 4 comprise a circular plate 30 having slighly reduced diameter in comparison with the inner diameter of the guide sleeve 3. On the one side of plate 30 a pair of radially extending wings 31 are provided extending slighly beyond the periphery of plate 30. On the opposite side of the plate 30 a pair of axially extending arms 32 are provided, said arms being resilient and provided at the outer free ends with outwardly extending hooks 33. These hooks 33 are adapted in the tensioned condition to rest behind a shoulder 23 and 24 respectively, a pressure spring 5a, 5b being inserted about the arms 32 between the plate 30 and the respective shoulder 23, 24. Each of the wings 31 has a downwardly and inwardly sloping surface 34. For releasing the sampling device these surfaces 34 cooperate with the hooks 33 of the arms 32, the hooks 33 sliding along the surfaces 34 and being shifted towards each other which means released from their engagement with the respective shoulder 23, 24. The wings 31 are guided in slots 20, 21 thus preventing a rotation of the needle holders 4 in relation to the guide sleeve 3. The wings 31 extend through slots 20, 21 towards the inner surface of the tensioning sleeve 2, however, suitably not into contact therewith in a radial direction but into abutment with the cam surfaces 11, 12 therein. The assemblage of the driving unit 1 is performed substantial in the following way: The two needle holders 4a, 4b together with their needles 7a, 7b and with the springs 5a, 5b positioned about arms 32 are placed in position in the one half of the guide sleeve 3 and also the trigger knob 6 is inserted therein, whereafter the other half of the guide sleeve 3 is placed on the first half. Thereafter, the tensioning sleeve 2 is passed over the guide sleeve 3 causing the tongues 10 to enter into groove 16, while the opposite end of the tensioning sleeve 2 encloses the guide sleeve 3 at the depression 17. In this position the unit is ready for use. It will be appreciated that the parts used are of simple and cheap construction, to the extent possible consisting of plastics or similar material, only springs 5a, 5b and the needles 7a, 7b proper consisting of metal and in addition being light-weight. The driving unit of the sampling device operates as follows: The sampling device, which in itself is one of the single-use type, may be loaded several times without problems and is manufactured with different needle thicknesses and needle lengths depending on the specific use. The physician thus chooses a sampling device adapted for the sampling in question. This device, however, is not initially tensioned in order to avoid deformation of certain parts due to the spring forces, but tensioning is to be performed immediately prior to sampling. For this purpose the handle 14 is held with the one hand whereas the other hand seizes the tensioning sleeve 2 to perform relative rotation of these parts. The wings 31a of the forward needle holder 4a thereby will be shifted along the steep portion of the cam surface 12 which means that the forward spring 5a will be compressed. The wings 31b of the rear needle holder 4b follow at the same time the flattened portion 36 of the cam surface 11 to arrive at the end behind catch 37. In this position backward rotation to the starting position is no longer possible, but the rear needle holder 4b is raised to such an extend that it cannot come into contact with the hooks 33a of the forward needle holder 4a when these enter into the locking position behind the intermediate shoulder 23. During continued rotation the forward wings 31a follow the plane cam surface 38a whereas the rear wings 31b follow the steep cam surface 39 causing the rear spring 5b to be compressed. If now the physician looses hold, the rear needle holder 4b moves towards the starting position but is retained in front of catch 37 and thus cannot release the forward needle holder 4a. When wings 31b have been advanced along cam surface 39 during continued rotation, they are lifted over a catch 40 and thereafter reverse rotation is impossible and continued rotation is prevented by an abutment 41. In this position the recesses 26 are situated exactly oppostie grooves 25 in the guide sleeve 3 and the triggering knob 6 may be depressed. The sampling device is now tensioned and ready for sampling. The triggering knob 6 is connected to a cross element 42 having a substantially V-shaped depression 43 in its central portion. When the triggering knob 6 is depressed, which is possible due to the fact that grooves 25 and 26 are mutually aligned, the flanges of the V-shaped portion 43 will urge hooks 33b towards each other causing them to loose contact with shoulder 24 and enabling the spring 5b to propel the inner needle 7b. When the needle holder 4b approaches shoulder 23 it performs the same function as previously performed by the triggering knob and releases the forward needle holder 4a from its engagement with the intermediate shoulder 23. Consequently, the inner needle 7b having a tissue-receiving cavity, is propelled first whereafter the tubular outer needle is released to resect the tissue received in said cavity. If additional samples are to be taken, the first needle 7a is to be withdrawn which means that the sleeve 2 is to be rotated in relation to handle 14 to the first locking position in which the wings 31b are retained behind catch 37. In the embodiment shown the wings 31 of the needle holders 4a, 4b extend in both directions which means that they cooperate with one cam surface each. Due to this, these cam surfaces must be relatively steep because both springs are to be tensioned during half a turns rotation of the tensioning sleeve 2 in relation to the guide sleeve 3. By providing the needle holders with only one wing adapted to cooperate with cam surfaces in the tensioning sleeve 2 these cam surfaces may be flattened as the tensioning of both springs in this case may be performed during a full-turn rotation. In the embodiment shown the needles 7a, 7b are so positioned as to extend centrally from the driving unit 1. If the sampling is to be performed with the aid of additional apparatus means, e.g. an ultrasonic apparatus in order to determine the penetration of the needle unit, such a positioning of the needle may be less suitable. Accordingly, other positions of the needles, e.g. eccentric positioning, is within the frame of the invention. The expert on this field will realize that the driving unit according to this invention fully achieves the initially defined purpose. The expert also will realize many possible variations and modifications of the invention. However, such variations and modification are intended to fall within the frame of the invention as defined in the attached claims.

Claims: Driving unit for a device for taking tissue samples, said device in addition to the driving unit (1) comprising a guide sleeve to which is mounted a needle unit consisting of two sequentially arranged needle holders (4a, 4b) carrying respectively an outer (7a) needle and, slidably disposed therein, an inner needle (7b) having a cavity near its tip, said needle holders being shiftable in relation to each other longitudinally, and adapted to be pre-tensioned in the same direction for propelling said needles (7a, 7b) by means of one spring (5a, 5b) each, said driving unit (1) comprising a drive (4b, 5b, 7b, 24) for propelling said inner needle (7b) and a drive (4a 5a 7a 23) for propelling said outer needle (7a) each of said drives being provided with a spring mechanism adapted to be pretensioned, and a tensioning device (31a 31b) for pretensioning the spring mechanism, the drive for the inner needle further being provided with a triggering device (6) to be actuated from outside of the unit for releasing said drives in such a way that the inner needle is first extended out of the outer needle followed by the outer needle resecting and covering a tissue sample in said cavity, the needle holders (4a, 4b) being provided with releasable locking means (33a, 33b) performing the locking function in cooperation with elements (23,24) provided in said guide sleeve (3) the triggering device (6) being adapted to be manually operated for releasing the needle holder (4b) of the inner needle (7b) which in turn is adapted to release during the final phase of its propulsion the needle holder (4a) of the outer needle (7a), the needle holders (4a, 4b) being pre-tensioned against the action of the springs to a position in which the locking means (33a, 33b) in question is locked by cooperation with the respective elements (23, 24), characterized in that a tensioning sleeve (2) rotatably surrounds said guide sleeve (3), and that the inside of the tensioning sleeve (2) is provided with cam profiles (11, 12) cooperating with the needle holders (4a, 4b) in such a way that during rotation of the sleeves (2, 3) in relation to each other, said pre-tensioning of the needle holders (4a, 4b) takes place. Driving unit as claimed in claim 1, characterized in that the cam profiles (11, 12) are so shaped that the pre-tensioning of the needle holders (4a, 4b) occurs sequentially. Driving unit as claimed in claim 1 or 2, characterized in that the cam profiles (11, 12) are provided with catches (37, 40) preventing both return turning of the sleeves (2, 3) in relation to each other and unintended release of the driving unit. Driving unit as claimed in any of the preceding claims, characterized in that the triggering device (6) is operable for releasing the driving unit only in a position in which both needle holders (4a, 4b) are in pre-tensioned, locked position. Tissue sampling device, comprising a driving unit according to any of claims 1-4.

Inventors: AKERFELDT DAN, AKERFELDT, DAN
Applicants: BARD INC C R, C.R. BARD, INC.
Application year: 1988
Main classification: A61B10
IPC codes: A61B10