A cannula (from Latin "little reed"; plural cannulae or cannulas) is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of data. In simple terms, a cannula can surround the inner or outer surfaces of a trocar needle thus extending the effective needle length by at least half the length of the original needle. Decannulation is the permanent removal of a cannula (extubation), especially of a tracheostomy cannula, once a physician determines it is no longer needed for breathing.