A cannula for the drainage of a vena cava

Claim 1

A cannula for the drainage of the venae cavae for establishing an extracorporeal blood circulation, made of a semirigid plastic material, characterized by the fact that the cannula (1, la) has at one of its end (3) a tip (3a) shaped as a fluted mouth, and at the other end the female element (5) of a bell-and-spigot joint, and that at the end portion (3) of the cannula (l, la) near the tip (3a) thereof a sleeve (2) made of an elastically deformable material, rubber, for instance, is mounted around the cannula (1, la), said sleeve (2) being connected to the outer surface of the cannula (1, la) by fixing the annular edges (2a) of said sleeve (2) to the cannula wall by means of an adhesive or the like, so as to define therebetween an annular space (12) of variable volume, into which opens the orifice of a small pipe (6, 6a) the first length (6) of which passes longitudinally through the thickness of the cannula wall, while the second length (6a) thereof is positioned on the outside and includes an external pressure gauge (7), said pipe (6, 6a) being connected with a source of pressurized fluid which is supplied into the annular space (12) in such a quantity so as to increase the volume thereof and let expand the sleeve (2) so as to obtain a seal closure between the outer surface of the sleeve (2) and the inner surface of the vena cava (C s or Ci).