Gels or other liquids or solutions are administered during laparoscopic surgery to prevent tissue adhesion or to wash or moisten tissues. In laparoscopic surgery, for example of the abdomen, surgical instruments may be inserted through a tubular port incorporating a valve adapted to retain a positive gas pressure within the body cavity. W097/36622 discloses a laparoscopic gel applicator comprising an elongate instrument with a flexible delivery tube having a distal end with a nozzle. The nozzle may be flexed to dispense with a desired pattern into a spray head located in use within the abdominal cavity. A syringe may be used to push gel through the dispensing tube to the distal end thereof.

Laparoscopic barrier fluid materials may be non-Newtonian viscous gels. For optimum efficient use a film of generally constant thickness should be dispensed into the body cavity to form a laminar sheet.

According to the present invention a laparoscopic gel applicator comprises a reservoir for laparoscopic gel material, the reservoir being connected to a proximal end of an elongate tubular member, a dispensing head being connected to a distal end of the tubular member; a pump adapted to urge gel material from the reservoir through the tube to the head; the head including one or more apertures through which gel material may pass into a patient's body cavity in use; wherein said one or more apertures extend in an axial direction of the dispensing head between a proximal and distal end thereof to allow extrusion of a film of gel material through the said apertures between said proximal and distal ends in use, the said one or more apertures including respective regions of reduced cross-sectional area to act as flow restrictors in use, the reduction in cross-sectional area increasing from the proximal to the distal end.

In a preferred embodiment a dimension of the one or more apertures perpendicular to said axial direction increases from the proximal end to the distal end.

An applicator in accordance with the present invention confers the advantage that the greater restriction on flow of the gel material at the proximal end of the aperture in relation to a lesser restriction at the distal end may be selected to compensate for the increased distance which the viscous gel must pass to reach the distal end. Thus the flow of gel material from the apertures is more uniform providing a generally laminar extruded film in the body cavity.

The aperture or axially extending array of apertures may be dimensioned to restrict flow of gel material, the restriction decreasing from the proximal to the distal end. The restriction may be achieved by decreasing the diameter of the aperture or a portion thereof.

Alternatively the length of the aperture from a central bore in the dispensing head may decrease from the proximal end to the distal end, thereby making flow easier at the distal end.

In preferred embodiments of the invention the dispensing head is rotatable to facilitate control of the direction of application. The elongate tube may be flexible or rigid.

In preferred embodiments of the invention the elongate tube may incorporate a portion formed from a shape memory alloy to provide a flexible conduit for the flow of gel material.

Suitable shape memory alloys for use in the device of the invention include binary alloys, such as those in which the nickel content is at least about 50 wt. %, preferably at least about 50.5 wt. %. The nickel content will usefully be less than about 52 wt. %, preferably less than about 51 wt. %. The device can be formed from other Ni-Ti based alloys, including alloys with ternary and quaternary additions. Examples of elements that can be incorporated in the alloy include Fe, Co, Cr, Al, Cu and V. Added elements can be present in amounts up to about 10 wt. %, preferably up to about 5 wt. %.

Techniques for making tubular members of this kind from shape memory alloy materials are known. Such techniques can be used to make products such as cardiovascular stents. Generally, the drive member will be made from a tube of the alloy, by removing material by an operation which involves cutting, melting or vaporising the material. It is particularly preferred that the drive member by made by a laser cutting technique, but other cutting techniques might include stamping, cutting, and etching (especially photoetching).

Known laser cutting techniques which can be used in this way include the use of a YAG laser.

The pump may comprise a syringe driven either manually or mechanically, for example by compressed gas. Alternatively peristaltic pump may be employed.

The invention is further described by means of example but not in any limitative sense with reference to the accompanying drawings of which: Figure 1 illustrates a dispensing head of a laparoscopic gel applicator in accordance with this invention; Figure 2 illustrates an alternative dispensing head; Figure 3 illustrates a dispensing head; Figure 3 illustrates a syringe pump in accordance with this invention; and Figure 4 illustrates a manually driven pump in accordance with this invention.

The laparoscopic gel applicator is described with reference to Figures 1 and 3.

Figure 1 illustrates an electrically powered compressor 1 which serves to pump compressed air through a tube 2 to a syringe 3 containing a reservoir 5 for adhesion barrier gel material.

Downward motion of the piston 3 drives the gel through outlet tube 4 to the dispensing head 5 shown in Figure 1. The dispensing head comprises a generally hollow cylindrical member 6 having an axially extending slot 7 through which the gel material 10 is extruded in use. The radial width of the aperture 7 increases from the proximal end 8 to the distal end 9 making flow of the viscous gel easier towards the distal end.

The outlet tube 4 may have a portion formed from shape memory alloy to facilitate flexing of the dispensing head during use. The flexible portion is preferably located adjacent the dispensing head as shown in Figure 1.

Figure 2 illustrates an alternative embodiment wherein an array of apertures 20 extend axially so that a continuous sheet of gel may be extruded from them. The diameter of the apertures increases from the distal to the proximal end.

Figure 4 illustrates a manually driven pump having a pistol grip 30 arranged to drive a piston 31 within a syringe 32 to drive gel into an outlet tube 33 connected to the dispensing head (not shown).

Figures 5 to 7 illustrate an alternative embodiment of the dispensing head shown in Figure 1. In this embodiment the hollow cylindrical member 40 connected to outlet tube 41 has an axially extending outward slot 42 communicating with a generally conical chamber 43 within the hollow member 40. The radial dimension of the chamber 43 increases from the proximal end 43 a to the distal end 43b to ensure an even pressure of gel along the length of the outlet slot 42. This facilitates dispensing of a laminar sheet of the gel material.