GB2425483A

GB2425483A - A single step trocar based insertion device

Info

Publication number: GB2425483A
Application number: GB0508738A
Authority: GB
Inventors: Hans-Ulrich Laasch; Stavros Michael Stivaros; Anthony James Maxwell
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-04-29
Filing date: 2005-04-29
Publication date: 2006-11-01
Also published as: GB0508738D0

Abstract

A flexible wire guided trocar with a cutting tip 13. Preferably the device is combined with a sheath 18 for creating a large track in bodily tissue in a single step. The device may be used for direct insertion of other devices or for inserting an access port. The cutting tip 13 may be integral or made of a different material to the shaft 14 and it may have a bevelled tip or multiple cutting ridges. The device may have a hollow bore allowing passage of a guidewire 4 and a secondary bore for injection of a material or aspiration. The sheath 18 may of the peel away type or left in situ to act as an access port. The flexible trocar may be advanced over a guidewire 4 using the Seldinger technique during laparoscopic surgery or insertion of a gastronomy tube.

Description

A Single Step Trocar Based Insertion Device The present invention relates

to a flexible cutting trocar to be used for the safe creation of large access tracks in human or animal tissue for possible further procedures or investigations, or as a means to insert further medical equipment for treatment, or afford direct access into the body. The device finds particular, but not exclusive, use in the creation of large access tracks through the skin for the single step insertion of large diameter catheters for drainages of, for example, pleural or peritoneal fluid, for the insertion of catheters into the vascular system for vascular interventional procedures, for the insertion of access ports for laparoscopic surgery and for obtaining access into hollow organs, for example the stomach or bowel, for the insertion of feeding or drainage tubes.

Using percutaneous access to the stomach as an example: Gastrostomy insertion is a procedure whereby a hollow tube is ultimately positioned with one end within the stomach, and the other end being located outside the body. They are primarily used for the feeding of patients who are not able to take oral feed for whatever medical reason (safety, anatomical derangement amongst other causes) The sequence of events culminating in the final placement of the gastrostomy tube are summarised below.

An initial puncture is made into the stomach (1) from a point on the skin (2), after the stomach has been inflated with an inert gas (usually room air) . This puncture is performed with a hollow bore needle (3) of approximately one and a half millimeters diameter, as shown in figure 1. A guidewire (4) is placed through the hollow bore needle which is in situ with its end within the stomach. The wire is therefore located with one end outside the body, passing through the needle such that the other end is located within the stomach figure 2. The needle can then be removed by sliding it off over the wire. This leaves the wire itself partially coiled within the stomach, coming through the stomach wall and overlying tissues, the end being located without the body. Using this wire as a semi rigid guide, the skin and deeper tissue tracks which the wire passes through can then be dilated using plastic dilators (figure 3, reference number 5)which are passed over the wire. These plastic dilators are of ever increasing sizes and the track is therefore dilated until such time as the it is wide enough to accommodate the requisite sized feeding tube (approximately five to seven millimetres in diameter), these dilators and their use is summarised in figure 3.

Note that these dilators are in effect crushing the surrounding tissues as they displace them, damaging the tissues they are displacing. In addition there is a certain amount of force required to advance the dilator and crush the tissue as it is advanced which may damage the dilator as well as the guidewire or surrounding tissues figure 5. Due to the force required displacement of the guidewire from the stomach may also occur.

Alternatively, once the wire is located within the stomach, the dilatation of the track can be performed with a balloon inflation device (figure 4, reference number 6) This device is passed over the wire such that the balloon is located across the tissue that needs to be dilated.

Once there, the balloon (7) is inflated, which as it expands has the effect of expanding the tissue track to the required size as shown in figure 4.

Figure five demonstrates that once the track is of the required size the gastrostomy tube (8), which frequently has a retaining mechanism for example but not exclusively a balloon (9), can be inserted. This is often performed through a temporary sheath which can be removed (10) (for example by tearing which is known as a peel-away sheath) once the gastrostomy tube is in the correct position within the stomach, extending through the stomach wall, subcutaneous tissues and skin to the outside.

It is generally accepted by those medical practitioners who frequently perform the insertion of gastrostomy tubes that there are several disadvantages to the technique described above. Serial dilatation of the track is time consuming, especially for large tracks (greater than 3mm in diameter) . In addition the procedure of serial dilatation carries the risk of losing access to the stomach. As successive dilators are removed and reinserted the wire can kink rendering it unusable and the procedure needs to be aborted. Also the wire can come out of the stomach itself with the same result. Balloon dilatation is expensive and frequently unsuccessful with suboptimal dilatation.

As discussed earlier the current invention pertains not only to the insertion of gastrostomy tubes, but also for the creation of access tracks into what are termed virtual spaces, for example but not exclusively, the pleural space for thoracoscopy or peritoneal space for laparoscopic surgery. Currently the track in these cases is created through the use of a solid trocar which is frequently made of surgical grade stainless steel. The trocar is usually pushed blindly through the skin into the cavity which needs to be accessed, cutting as it goes by virtue of its sharpened bevelled tip. These trocars are often of large diameter, (1 centimeter and larger) and have a closely applied sheath around them. Once in the cavity, the trocar can be removed leaving the sheath in situ as an access port. It will be apparent to the skilled reader that solid trocars of this type carry a serious risk of injury to adjacent structures such as heart, lung, bowel or aorta to name but a few. In addition their exact location cannot be ascertained as they are solid, which negates the instillation of radiopaque contrast media through them. This means that x-ray guidance of the point of the trocar is not possible.

Aspiration through the solid trocar is also not possible which negates this as a safety procedure during insertion.

It is only once the trocar is removed and the port left in situ that its exact location can be determined. Even so, should the trocar be accidentally traversing a structure such as a blood vessel or a ioop of bowel this may only become apparent once the sheath itself is removed.

The proposed device combines the following features which when combined provide a new and novel form of device for the creation of wide bore access tracks. These features are namely a flexible dilator of the required final track diameter, which has a cutting tip and a central channel which allows for its insertion over a guidewire. In addition there is a Luer-type connector at the blunt end, which allows for the injection of contrast medium either through the guidewire channel or a secondary bore through the device. The whole device is combined with an outer removable sheath or access port in the form of a closely applied jacket which can be inserted at the same time as the device in a single step procedure.

The skilled reader will have ascertained that this new device will allow for the safe insertion of a large bore port or sheath in a single step without the need for serial dilatation, or the inherent risks of a solid non- flexible trocar. Wire guidance minimises the risk of perforation to other viscuses or structures. The edges of the dilator cut rather than stretch the track minimising the stress on the surrounding tissues and the resulting risk of displacement of the organ wall. This in turn reduces the stress on anchoring sutures (e.g. gastropexy where the stomach wall is brought in close apposition to the abdominal wall reducing the distance between them and anchoring the stomach to the abdominal wall with, for example but not exclusively, sutures. This aids in the insertion of devices through both structures minimising the risk of organ displacement or a loop of bowel interposing itself between skin and stomach wall) The flexibility of the device in addition to the cutting tip combines the robustness of a steel trocar with the safety of wire guidance.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which: Figure 6 shows a prior art trocar (11) which is all metal, including the metal bevelled cutting tip (12); Figure 7 shows a flexible trocar according to an embodiment of the invention. This has a simple plastic cutting tip (13) to create a large track up to the size of the flexible shaft (14) during a single insertion. This removes the need for repeated insertion of serially increasing sized dilators which do not have the capacity to cut the tissue and therefore have to stretch it. The device may be created from flexible plastic such that it can bend as it follows the path of the guidewire which has previously been inserted by the technique already established, with the cutting tip (13) made from plastic and moulded as one single unit.

Note that the cutting tip (13) may be of slightly smaller diameter than the shaft of the dilator (14) to allow for some compression of the surrounding tissues to reduce bleeding and leakage.

Alternatively as shown in figure 8, the cutting tip (14) may be manufactured from alternate material such as but not exclusively surgical grade stainless steel, a different plastics material or a ceramic. This is mated to the flexible shaft of the device (14) which provides the flexibility required to pass over the guidewire (4) which passes through the hollow central channel (15).

Figure 9 shows a design for the cutting tip (13) which demonstrates the most simple design of a simple bevelled cutting edge (17).

Figures 10 (in longitudinal section) and 11 (in cross section) demonstrate a further embodiment of the cutting tip with longitudinal serrated cutting edges arranged parallel to the long axis of the device (18) . The edges in this example number 4, but there may be a plurality of edges.

Figure 12 shows the addition of concentric cutting grooves (17) which when combined with the longitudinal cutting edges (16) creates serrated cutting edges. This gives further cutting ability to the flexible device. Again the grooves in the longitudinal (16) or concentric (17) dimension parallel to the long axis of the device, may be single or multiple in any numeric combination. In addition the angle the concentric grooves (17) make to the longitudinal edge is not implicitly 90 degrees but may be any angle which means that a spiral groove may also be considered. Note also the central hollow channel (15) of the device of the order of 1mm in diameter specifically to accept guidewires of the standard diameters 0.035 and 0.038 inches.

Figure 13 demonstrates an outer sheath(18) which may be of the peel-away type.

Figure 14 illustrates the flexible cutting tip trocar being combined with the sheath (18) by passing it through the sheath. This allows it to be closely applied to the shaft (14) of the trocar.

Figures 15 and 16 show this combination which can then be passed over a guidewire and can be inserted in a single step into (for example) the stomach which may have been fixed to the abdominal wall with a gastropexy device/s (19.

Figure 17 shows that following removal of the trocar the sheath (18) remains in situ and secures the track allowing the subsequent insertion of, for example but not exclusively, feeding tubes such as gastrostomy tubes (8), or drainage tubes or surgical instruments.

Figure 18 shows that the flexible cutting tip trocar may also be passed through other medical devices and not only sheaths. For example the trocar may be used as a stra.igtener or stylet within a differently designed feeding tube 20. This would also allow for a variation in the design of the device, namely the shaft (14) and the cutting tip (13) whereby a locking mechanism is incorporated, for example but not exclusively, a bayonet mount or a locking pin such that the trocar would be secured to the device it is inserted through such as a feeding tube (20) . This allows the insertion of the feeding tube with the trocar over a guidewire in a single step (figure 19) . When the trocar is subsequently withdrawn the feeding tube (20) remains in situ (figure 20) Figure 21 shows an embodiment of the device which has an associated secondary hollow channel(21) which may be accessed from a Luer or other type of connector (22).

This allows the injection of material through the device to emerge at an opening near to the device tip (23) or side (24), allowing the injection of contrast material (iodinated x-ray visible contrast medium as an example), or allows for the aspiration of material from the viscus or cavity in which the device is sat to the external region.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification, in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features

disclosed in this specification (including any

accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A flexible trocar with a cutting tip that may be wire guided.

2. A device as claimed in 1 which can be combined with an outer sheath of any kind to be used for the creation of a large track in tissue of the human or animal body in a single step.

3. A device as claimed in 1 which may be used for either direct insertion of other devices through the track e.g. a feeding tube into the stomach or for the insertion of an access port for laparoscopic surgery comprising:

4. A flexible wire guided cutting trocar as claimed in claim 1 wherein the cutting tip is made of the same material as the shaft and is hence physically an integral part of the shaft during creation.

5. A flexible wire guided cutting trocar as claimed in claim 1 where the cutting tip is made of a different material than the shaft e.g. another plastics material or a metal such as (but not exclusively) stainless steel or a ceramic.

6. A flexible wire guided cutting trocar as claimed in claims 1, 2 or 3 where the cutting tip is a simple cutting bevel edge of one or a plurality of bevelled edges to allow for cutting of tissues

7. A flexible wire guided cutting trocar as claimed in claims 1, 2 or 3 where the cutting tip is comprised of a series of longitudinal cutting ridges parallel to the long axis of the device which may be multiple, arranged in a radial fashion extending outwards from the centre of the cross section of the device.

8. A flexible wire guided dilator as claimed in claims 1, 2 or 3 where the cutting tip is comprised of a series of longitudinal cutting ridges parallel to the long axis of the device which may be multiple and are arranged in a radial fashion extending outwards from a point eccentric to the centre of the cross section of the device.

9. A flexible wire guided cutting trocar as claimed in claims 7 and 8 with an additional series of concentric cutting ridges arranged at an angle to the longitudinal cutting ridges which may be but not exclusively 90 degrees which allows further cutting potential to the cutting tip.

10. A flexible wire guided cutting trocar as claimed in and preceding claim which has a hollow bore allowing the passage of a guidewire which the device will follow due to its flexibility.

11. A device as claimed in any preceding claim wherein there is a secondary bore which is open to both ends of the device allowing the injection of material or aspiration from the space in which the device has been placed without the need to remove the guidewire.

12. A device as claimed in any preceding claim wherein the shaft has a closely applied sheath which may be left in situ once the cutting dilator is removed, leaving the sheath in effect acting as an access port

13. A device as claimed in claim 10 where the sheath is the peel-away type which may be removed following the insertion of any other device through the access port such as a gastrostomy.

14. A device as claimed in claim 10 where the sheath is a plastics, metal or ceramic material which provides structural rigidity and may be left in situ to act as a more robust access port for example as used in laparoscopic surgery.

15. A flexible trocar with a cutting tip that may be wire guided substantially as herein described above and illustrated in the accompanying drawings.