US Patent 7597688 Cannula apparatus with inflatable seal and adjustable length

A cannula has a tubular body, an inflatable ring affixed within the tubular body adjacent proximal end thereof, and a valve connected to a channel extending to the inflatable ring. The valve is suitable for allowing a liquid to be passed into the inflatable ring from a syringe. The inflatable ring is expandable into the longitudinal channel when the liquid is introduced thereinto. The tubular body has an outer sleeve adjustably receiving an inner sleeve at the distal end of the tubular body. Numerical indicia are formed on the inner sleeve.