He inserted a cannula of silver through the mouth until its head met an obstruction.
The rim surrounding the mouth of the cannula should be in contact with the skin.
The operation is performed with a combined instrument called the trocar and cannula.
Intubation, or the passage of a cannula through a stricture, is referred to later.
Attached to the handle was a thumb-rest and a tube for removing or adding fluids and a perforator within the cannula.
Inside the cannula is fixed by oxidation an obturator, which carries on its end a small handle fixed on in T-fashion.
The iodoform is injected by means of a glass-barrelled syringe, which is firmly screwed on to the cannula.
Wind colic may need prompt use of the trocar and cannula to puncture high up in the right flank for liberation of gas.
The trocar is a sharp-pointed instrument incased in a cannula or sheath, which leaves the sharp point of the trocar free.
It is well, accordingly, to observe the cannula closely, and if gas is found to be issuing from it it should not be removed.
