Accessory for arranging a surgical instrument within a cannula shaft

A method for delivering gases to a surgical site, the method including:

• inserting a surgical instrument into a bore defined in a body of a sheath to define a first flow path between the body of the sheath and the surgical instrument;
• the body of the sheath further defining:
• at least one aperture arranged to allow fluid flow into the bore and along the first flow path when the at least one aperture is positioned at a first location relative to a cannula shaft,
• a plurality of internal projections extending into the bore and configured to position the body of the sheath relative to the surgical instrument, and
• a plurality of external projections extending away from the bore and configured to position the body of the sheath relative to the cannula shaft,
• the body of the sheath comprising:
• a proximal portion comprising an open proximal end,
• a distal portion comprising an open distal end, the bore defined between the open proximal end and the open distal end,
• an intermediate portion interposed between the proximal portion and the distal portion and configured to seal against the cannula shaft, and
• the body of the sheath further defining a tapered region extending away from the intermediate portion, the at least one aperture defined in the tapered region, and
• inserting the sheath into the cannula shaft such that the at least one aperture is positioned at a second location relative to the cannula shaft to define a second flow path between the body of the sheath and the cannula shaft;
• and
• conveying gases through one or more of the first flow path and the second flow path to exit into the surgical site.

A sheath for a surgical instrument, the sheath including:

• a body defining:
• a bore configured to receive the surgical instrument such that arranging the surgical instrument within the bore defines a first flow path between the body and the surgical instrument,
• at least one aperture arranged to allow fluid flow into the bore and along the first flow path when the at least one aperture is positioned at a first location relative to a cannula shaft,
• a plurality of internal projections extending into the bore and configured to position the body relative to the surgical instrument, and
• a plurality of external projections extending away from the bore and configured to position the body relative to the cannula shaft;
• the body comprising:
• a proximal portion comprising an open proximal end,
• a distal portion comprising an open distal end, the bore defined between the open proximal end and the open distal end,
• an intermediate portion interposed between the proximal portion and the distal portion and configured to seal against the cannula shaft,
• the body further defining a tapered region extending away from the intermediate portion, the at least one aperture defined in the tapered region, and
• wherein the internal projections are configured to direct fluid flow axially through the bore along the first flow path to pass the surgical instrument arranged within the bore, and the external projections are configured to direct fluid flow axially adjacent the sheath through a second flow path when the at least one aperture is positioned at a second location relative to the cannula shaft to pass the sheath and the surgical instrument arranged within the bore.