GB2298906A - Modular seal system for trocars - Google Patents

Abstract

A seal module (6) Fig 1 comprises a gas impermeable instrument seal 10 extending across a chamber and secured to make a substantially gas-tight seal with the internal wall of the chamber, said instrument seal has a central elastic disc shaped portion with an opening which can be stretched to accommodate the passage of elongate instruments of different cross-section to form a substantially gas-tight seal with such instruments. There is also provided a seal system which is active when no instrument is inserted. Two or more mechanically biased guides 1, 3 locate instruments of 6mm or less and are pivoted, but mechanically biased into the locating position. When a larger instrument is inserted, say 10mm in diameter, the guides, by use of pivots 5, 7 are pushed away to allow the entry of the 10mm instrument without difficulty. The gas is sealed by a flap valve 9 which seats on the guides which themselves seat on a support cap.

Description

MODIJLAR SEAI, SYSTEM FOR TROCARS The present invention relates to gas-tight seals and to trocar systems incorporating such seals.

Trocar svstems are used during abdominal operations for maintaining a passage through the abdominal wall of a patient.

Trocar systems genera}y comprise ? cannula in the forr of an el;:igate tube terminating in an enlarged upper body and an obturator or cutting tool which is fed through the enlarged upper body and down the elongate tube to pierce the abdominal wall so that the elongate tube can follow the tool through the wall. The cutting tool is then removed leaving the way clear for elongate surgical instruments or equipment, such as endoscopes. to be fed into the abdomen through the tube.To provide space witllin the abdomen, the abdomen is inflated with a gas and this allows easy access to Lhe vari'iis organs located witl.in tile abdomen. To maintain gas pressure the trocar system is provided with a flap valve which is urged by the pressure of gas into a closed state. The flap valve has, however, to be opened to allow the passage of surgical tools therepast. Accordingly a sealing system is provided in the enlarged upper body to provide a seal around the surgical instrument once it has been inserted into the enlarged upper body.This now creates a gas lock between the flap valve and the seal and so the flap valve can now be opened (either by pushing the instrument against it or by other meails) substantially without loss of pressure in the abdomen. The instrument can now be fed into the abdomen and manipulated as required. Usually more than one trocar is used so as to provide multiple entry points into the abdomen.

The diameter of the instruments used is usually much smaller than the diameter of the tube or the enlarged body and so a considerable amount of lateral off-axis movement of the instruments can and does take place in order to effect the desired manipulation of the instrument. Because the seals used are static any movement of the instrument other than axial is liable to strain the seal often to the extent of temporarily breaking the seal and so allowing gas to escape. Also most seals are designed with a specific diameter of instrument in mind and so different seals or adapters are required when changing instruments.

It is an object of the invention to provide an improved sealing system.

According to the present invention there is provided a seal comprising a gas impermeable instrument seal extending across a chamber and secured to make a substalltially oas-tight seal with the internal wall of the chamber said instrument seal having a central elastic disc shaped portion with an opening which can be stretched to accommodate the passage of elongate instruments of different cross-section to form a substantially gas-tight seal with such instruments. There is also provided a seal system which is active when no instrument is inserted.

Two or Inore mechanically biased guides with axial locating means of such a size that instruments of 6mm or less can pass thorough the locating system and be held appronmatelv axially without difficulty, are pivoted but mechanically biased in he axially locatil2 position. When a larger instrument is inserted say 1 Omm in diameter, the guides. by use of the pivots are pushed away to allow the entry of the 1 Omm instrument without difficulty. The gas is sealed by a flap valve which seats on the guides which themselves seat on the support cap.

A seal system embodying the present invention will now be described by way of example with reference to the accompanying diagrammatic drawings in which: Figure 1 is a section through a trocar system down which a surgical instrument can be passed; Figure 2 is a cross-section of the seal module; Figure 3 is a cross-section of the seal module with a small diameter instrument, for example a 5mm diameter instrument has been inserted; Figure 4 is a cross-section of the seal module in which a large diameter instrument, for example a 1 Omm diameter instrument has been inserted; Figure 5 is a plan view ofthe seal module showing the guide flaps; The trocar system shown in Figure 1 comprises an elongate tube 2 terminating in an enlarged upper body portion 4.The enlarged upper body portion 4 accommodates a removable seal module 6. The seal module 6 may be sealingly locked into the body portion 4 by a screw threaded cap 8.

An elongate medical instrument 12 (for example the optical probe of an endoscope) passes through the seal module 6 and the tube 2.

The seal module 6 is shown in more detail in Figure 2.

The module 6 comprises a cylindrical body portion 10 which is open at one axial end and closed by an end wall 14 at tloc opposite axial end. The end wall 14 has a central circuit opening @@. An instrument seal @@ extends across the inner chamber defined by the body portion 10. The instrument seal 18 has a flat outer circumferential portion having an outer circumference substantially equal to the inner circumference of the body portion 10. A cylindrical clamping ring 22 is located within the chamber to urge the circumferential portion 20 against the inner face of the end wall 14. A locking member 24 may be a push tit under a circumferential lip 26 at the open axial end of the body portion to lock the component ofthe module 6 together.In a modification other methods of locking the locking member in place may be used for example by using a circlip engaging a groove on the inner face of the body portion 10 or by means of a screw thread on the locking member engaging a corresponding screw thread on the inner face of the body portion 10. The locking member has an annular collar 28. The internal diameter of the locking member 24 and the clamp ring 22 are substantially equal to the diameter of the opening 16.

The instrument seal 18 has an aperture therein substantially smaller than the opening 16. For example the aperture may have a diameter, when the disc is unstressed, of less than a quarter of the diameter of the opening 16.

The diameter of the aperture in the disc, when unstressed, should also be smaller than the diameter of the smallest instrument that is intended to be used with the seal.

Because the disc is of an elastic material the aperture can be stretched significantly beyond its original size by the insertion of larger diameter instruments. For example the diameter of the aperture could be ignore than doubled so as to accommodate different instruments having a diameter in the range of from 4 to 13mm. There is also provided a guidance. This system comprises two support members 1 and 3 which are arranged to pivot around axes 5 and 7 and to be lightly mechanically biased to close such that a gas seal is made between the face of the locking ring 24 and the support members, and between the axial faces of the support members themselves. The support members have suitably manufactured orifices to hold axially elongate instruments of less than approximately 6mm in diameter.Such support members can t > pically have a shape as shown in figure 5. The effect of the support member is to locate an instrument that is less than 6mm on the axis of the cannula thereby prevening the instrument from straining the instrument seal and causing loss of gas. A further seal is required to prevent the escape of gas and this is provided by a simple flap valve 9 which is biased to close over the faces of the supports so that a gas seal is effective when no instrument is inserted.When an instrument of less than say 6mm is inserted. the support members remain in position but the instrument opens the flap valve giving access to the instrument seal which then prevents the escape of gas from the abdomen.

Should an instrument of say 10 mm be introduced, the flap valve opens and also the supports are lifted out of position as shown in Figure 4.

Again a gas seal is made by the instrument seal.

In operation the module 6 is locked into the enlarged upper portion of the body position 4 of the trocar system using the cap 8. Upon the insertion of the instrument 12 tloe flaps 1 and 3 are displaced to allow the passage of the instrument 12. The instrument is then passed through the instrument seal 18 which will form a tight seal about the instrument. Upon withdrawal of the instrument 12 any debris drawn by the instrument from the abdominal area will be scraped off the instrument by the instrument seal 18 and so there is little or no danger of such debris being lodged on the guide flaps to prevent complete closure of the flap valve upon withdrawal of the instrument. The complete closure of the flap valve thus again prevents the escape of gas from the module.

It will be appreciated that the module 6 can be manufactured as a disposable module to be discarded after a single use.

If the module is required to be ellsable it can readily be removed from the trocar and autoclaved. Instead the module can be subject to Gamma or ethyleneoxide treatment.

Claims (8)

CI,

1. A modular seal system for use in a dedicated trocar system to provide a gas-tight seal with an instrument passed through the seal the instrument has a vide range of diameters. the seal module comprising an instrument seal of an elastic material the instrument seal extending radially outwards from the axis of the seal module. An instrument support means which restricts the lateral movement of the instrument. The instrument support means incorporating a simple flap valve to provide a gas-tiollt seal when no instrument is inserted.

2. A seal module according to Claim 1 wherein the instrument support seal means are mechanically biased towards a closed poSition.

3. A seal module according to Claim 1 wherein a flap valve means is an integral part of the seal module body.

4. A seal according to any preceding Claim wherein said instrument seal is of silicone rubber.

5. A seal according to any preceding Claim wherein an instrument support means is of a plastic material.

6. A seal according to any preceding claim comprising a body defining said chamber. said chamber being generally cylindrical open at one axial end and closed at the opposite axial end except for a central opening substantially similar in size to said disc shaped portion an annular clamping ring sized to be accommodated in said chamber and to urge the circumferential portion of said membrane against the closed axial end of the chamber, a radially inwardly directed flange extending from said clamping ring and terminating in a central opening aligned with and having a size comparable with that of the central opening in said one axial end of said chamber and a locking member for locking the clamping ring in the chamber of said body.

7. A seal according to claim 7 wherein said locking member forms a snap fit with said chamber.

8. A seal according to Claim 7 or to Claim 8 wherein said locking member includes an annular collar for guiding said elongate instruments towards the opening in said membrane.