Title of Invention: FLOW RATE REDUCER FOR PERCUTANEOUS NEPHROLITHOTRIPSY

Technical Field

[0001] The present invention relates to a flow rate reducer for percutaneous nephrolithotrip sy .

Background Art

[0002] Percutaneous nephrolithotrip sy (PCNL) is an operation for the removal of stones. Under ultrasound guidance, a percutaneous puncture of the kidney is performed, preferably in correspondence with the stone to be treated. After positioning a safety guide wire and having dilated the nephrostomy with special dilators, an operative cannula or Amplatz sheath is positioned through which an instrument called nephroscope slides. The nephroscope visualizes directly the stone. Once viewed, the stone can be removed by basketing, if it is of small size; on the other hand, if its volume prevents its direct removal, it is crushed by means of an ultrasonic, laser or ballistic probe, and the fragments produced are removed. The fragments produced are then extracted with an instrument suitable for the size of the fragments produced.

[0003] The operating cannula can have different dimensions according to the type of instrument being used. Obviously, wider is the access, also of a few millimeters, greater is the variety of instruments, different from each other in their external diameter that can be introduced in the operating cannula.

[0004] In order to be able to obtain a good surgical vision, the fundamental points are an adequate flow of water or treatment liquid, a correct distension of the renal cavities and, obviously, a low bleeding.

[0005] Without a good distension of the kidney a surgeon does not have a cavity within which he can navigate with the instrument in order to be able to carry out the surgery. This distension must not be excessive, in order to not damage the kidney itself. However, the distension must be sufficient to prevent the walls of the organ from collapsing.

[0006] The correct distension of the renal cavities is obtained with a correct intrarenal pressure determined by the ratio between incoming water and outflowing water.

[0007] In traditional PCNL the operating cannula has a rigid plastic structure so as to allow instruments having rigid bodies of different diameters to correctly slide inside the operating cannula.

[0008] Generally, the operative cannula has a gauge sufficient to allow the passage inside it of instruments which supply various power sources useful for the purposes of the surgical treatment, such as laser, ballistics and ultrasonic power.

[0009] With technological advancement, endoscopic vision instruments have become increasingly smaller over time, thanks to the miniaturization of cameras, the use of optical fibers and more.

[0010] Therefore, ever smaller operating cannulas have been introduced on the market, inside which only small instruments can pass. The result of this is the impossibility of introducing inside these small-gauge operating cannulas all the instruments for the various power sources that may be useful during the PCNL.

[0011] In practice, the only power source capable of being used with small-gauge operating cannulas is the laser one that allows the fragmentation of the stones but does not make it possible to remove their fragments. It is clear that a large instrument can also introduce ballistic and ultrasonic power into the operative cannula by means of rod devices which, in addition to breaking the stone, also remove the fragments at the same time.

[0012] To achieve this, there is a need to use a large gauge operating cannula. If during an operation there were a need to introduce an instrument with a gauge smaller than the cannula gauge, for example a flexible nephroscope that allows more sloping areas of the kidney to be reached, the large gauge operating cannula would be too wide with the disadvantage of letting too much flushing water or liquid flow out with the result of the loss of renal distension.

[0013] In summary, the diameter of the operating cannula is equal from the beginning to the end of its length. The free cross section between the body of the surgical instrument, introduced inside the operating cannula, and the wall of the operating cannula itself is crossed by the flushing water or liquid in outflow.

[0014] In the course of the same surgery it may happen that it is necessary to insert instruments that are different from each other both as regards the gauge and as regards the capacity to introduce water.

[0015] The problem can arise above all with the insertion of instruments of small diameter which therefore leave an excessive free cross section between the instrument and the operative cannula with consequent excessive outflow of water which causes an excessive drop in intrarenal pressure with lack of distension of the operating space.

[0016] Therefore, the quantities that determine the greater or lesser distension of the renal cavities are the gauge of the operating cannula, the diameter of the surgical instrument introduced, the amount of water supplied by the instrument.

[0017] Currently, the quantity of water in the outflow depends directly on the three quantities mentioned above and cannot be changed because, once a specific operating cannula has been chosen, it is not possible to replace it depending on the surgical instrument used each time in the surgery. In fact, one way to change the amount of water in the outflow could be to replace the operating cannula with a smaller or larger one, but this is not feasible during the intervention as the operating cannula can only be removed at the end of the same.

[0018] US 2015/0119645 Al discloses a system for controlling pressure during percutaneous and endoscopic interventions. The system includes a sheath having a proximal end that can be closed by a cap to limit the outflow of irrigation until the prescribed pressure is reached. In one embodiment thereof, the cap has an inner surface that surrounds the outer surface of the sheath. In order to adapt to sheaths of different sizes, the cap can have a frusto-conical body able to be inserted by friction on the sheath. The cap has a closed end that includes an opening with a valve. The opening allows the body of the cap to receive endoscopes of different sizes.

[0019] It should be understood that the cap described by US 2015/0119645 Al is a frusto- conical tubular element adapted to be connected by friction to the operating sheath and having a proximal end with an opening closed by a valve adapted to form a seal around the endoscope and to prevent the outflow of fluid.

[0020] US 2007/0270788 Al discloses a cap adapted to at least partially close a passage opening of an optical fiber, allowing the fiber to rotate and translate. The cap has a cylindrical body with openings for the passage of the optical fiber at its ends. The fiber port cap is flexible enough to be installed and removed from the endoscope and provides a firm enough seal to allow movement of the fiber during use and prevent leakage of irrigant. The internal diameters of the passage ports of the optical fiber are substantially identical.

Summary of Invention

[0021] An object of the present invention is to provide a device which allows to obtain a correct equilibrium between incoming water and outflowing water, in order to maintain a correct intrarenal pressure.

[0022] To achieve the indicated object, the present invention provides a flow rate reducer for percutaneous nephrolithotripsy (PCNL) in which an operative cannula or Amplatz sheath having a cylindrical wall of constant gauge, and a kit of instruments of diameter smaller than the constant gauge of the operating cannula are used so that each of the instruments is able to pass through the operating cannula. The flow rate reducer consists of a tubular element having a distal end with a first internal diameter so that the distal end is able to be connected tightly to the operating cannula, and a proximal end having a second internal diameter smaller than the first internal diameter of the distal end such as to allow the passage, through the flow rate reducer, of a desired instrument of said kit of instruments.

[0023] The reducer, which can be made of elastic or deformable plastic material, can be applied to the external end of the operative cannula with the aim of making a gauge reduction in an easy, reversible and modular way according to the instrument to be introduced and passed through.

Brief Description of Drawings

[0024] Further features and advantages of the present invention will become most clear from the indicative, and therefore non-limiting, description of preferred but not exclusive embodiments of a flow rate reducer for percutaneous nephrolithotripsy as illustrated in the accompanying drawings in which:

[0025] [Fig.l] [Fig.l] is an overall perspective view showing an exploded view of an operative cannula or Amplatz sheath, a flow rate reducer according to the present invention in two alternative embodiments, and a surgical instrument shown schematically;

[0026] [Fig.2] [Fig.2] is a perspective view on an enlarged scale of the first embodiment of the flow rate reducer;

[0027] [Fig.3] [Fig.3] is a longitudinal cross-section view of the first embodiment of the flow rate reducer;

[0028] [Fig.4] [Fig.4] is a perspective view on an enlarged scale of the second embodiment of the flow rate reducer;

[0029] [Fig.5] [Fig.5] is a longitudinal cross-section view of the second embodiment of the flow rate reducer; and

[0030] [Fig.6] [Fig.6] is a partial perspective view of a variant of the second embodiment of the flow rate reducer.

Description of Embodiments

[0031] With reference to [Fig.l], shown in an overall exploded perspective view are an operational cannula 1 or Amplatz sheath, a flow rate reducer according to the present invention in two alternative embodiments indicated respectively as 2 and 3, and a surgical instrument indicated as 4. The operating cannula 1 is equipped with a cylindrical wall with constant gauge, and the surgical instrument 4, not further detailed, schematically represents only an instrument of a kit of instruments having a diameter smaller than the gauge of the operating cannula in order to pass inside.

[0032] As described in detail below, both embodiments 2 and 3 represent the flow rate reducer which generally consists of a tubular element having a distal end 20, 30, with a first internal diameter so as to be adapted to be connected tightly to the operating cannula 1 and a proximal end 21, 31, with a second internal diameter smaller than the first internal diameter of the distal end 20, 30. The second internal diameter of the proximal end 21, 31 is such as to allow the passage, inside the flow rate reducer 2, 3, of an instrument 4 having a diameter smaller than the second internal diameter of the proximal end 21, 31.

[0033] With reference to Figures 2 and 3, the first embodiment of flow rate reducer 2 is shown in a perspective view and in an enlarged longitudinal cross-section view.

[0034] The flow rate reducer 2, made of suitable material, which can be plastic or elastic material, is substantially a tubular element. It has an internal cavity comprising, coaxially and consecutively connected in the distal-proximal direction, a first cylindrical portion 22 with a diameter close to the diameter of the operating cannula 1, a converging truncated cone portion 23 and a second cylindrical portion 24 with a diameter greater than the diameter of the instrument to be inserted in the operating cannula 1.

[0035] The distal end 20 and the first cylindrical portion 22 of the first embodiment of reducer 2 is adapted to be inserted on the outside of the wall of the operating cannula 1. For maintaining a sealing, the tubular element has internally, in proximity of its distal end 20, a lip seal 25.

[0036] Alternatively, the flow rate reducer 2 has a distal end of the tubular element with an external diameter smaller than the gauge of the operating cannula 1 and is able to be inserted inside it, capable of being tightly maintained. This variant is not shown in the drawings.

[0037] To allow the application of the flow rate reducer 2 on the outside or on the inside of the wall of the operating cannula 1, the tubular element has an externally knurled portion 26, having an increased grip for manual gripping. The knurled portion 26 is designed to facilitate the coupling of the flow rate reducer 2 with the operating cannula 1. Advantageously, the knurled portion 26 is located near the distal end 20 of the tubular element.

[0038] It should be understood that the tubular element can be made with different dimensions. It is critical that its distal end is of such a diameter that it allows the coupling of the tubular element with the wall of the operating cannula 1 and that the proximal end 21 of the tubular element is such as to allow the through insertion of the desired instrument 4.

[0039] With reference to Figures 4 to 6, shown are the second embodiment of flow rate reducer 3 in an enlarged- scale perspective view and in longitudinal cross-section view, and a pipe clamp in partial perspective view, respectively.

[0040] The flow rate reducer 3 is made of suitable material, preferably plastic. It is substantially a tubular element having, similarly to the first embodiment, a distal end 30 able to be sealed to the operating cannula 1 and a proximal end 31 having an internal diameter smaller than that of the operating cannula 1. The tubular element has an internal cavity comprising, coaxially and consecutively connected in the distal- proximal direction, a first cylindrical portion 32 with a diameter greater than the diameter of the operating cannula 1, a converging frustoconical portion 33 and a second cylindrical portion 34 with a diameter greater than the diameter of the instrument to be inserted into the operating cannula 1.

[0041] The flow rate reducer 3 has a pipe clamp 5 on the tubular element, near its distal end 30, in particular at the first cylindrical portion 32 of the internal cavity of the tubular element.

[0042] The pipe clamp 5, as shown in longitudinal cross-section view in [Fig.5], comprises an annular elastic part 50 incorporated in the tubular element, near its distal end, and opposed fins 51 connected to the annular elastic part 50. The opposed fins 51 are suitable for widening and therefore locking the pipe clamp 5 in positioning and, respectively, in tightening the tubular element on the operating cannula 1.

[0043] [Fig.6] shows a variant of pipe clamp 6 which can be incorporated into the tubular element or be applied separately on it. The pipe clamp 6 has a ring annular elastic part 60, the ends of which terminate beyond the ring created by them, and push buttons 61 connected to the annular elastic part 60. In a conventional way, and for this reason not shown, the push buttons 61 are suitable for widen and then lock the pipe clamp member 6 in positioning and, respectively, in tightening the tubular element on the operating cannula 1.

[0044] Constructively, it is convenient that the tubular element of the flow rate reducer has an overall length of 3 cm and its first cylindrical portion near the distal end has a length of 1.5 cm with a constant internal diameter. These dimensions are not intended as limiting features.

[0045] It is convenient for the overall length of the flow rate reducer according to the present invention to be as limited as possible so as not to negatively affect the maneuverability of the instrument itself and therefore on the correct success of the surgery. The application or removal of the flow rate reducer as needed allows the universal use of an operating cannula of only one gauge.

[0046] The flow rate reducer can be made with a first cylindrical portion of its tubular element such as to be coupled tightly with the operating cannula in use and with a second cylindrical portion, i.e. the proximal one with an internal diameter greater than the diameter of the instruments to be used in a specific surgical operation. If surgical instruments with a diameter other than that envisaged were to be used, it is sufficient to remove the flow rate reducer in use and apply another flow rate reducer to the proximal end of the operating cannula that has a second cylindrical portion of a diameter suitable for regulating the water or liquid in the outflow and therefore maintain the correct intrarenal pressure.