Polypropylene canula for continuous intravenous infusion

Claim 1

A THERAPEUTIC DEVICE COMPRISING AN INNER METAL CANULA HAVING A CUTTING EDGE AT THE FORWARD END PORTION THEREOF, A FLEXIBLE, SUSBTANTIALLY NON-DISTENSIBLE CANULA FORMED OF A PHYSIOLOGICALLY ACCEPTABLE POLYPROPYLENE PLASTIC MATERIAL POSITIONED ABOUT SAID METAL CANULA COAXIAL WITH THE SAME, THE FORWARD END OF THE PLASTIC CANULA ADJACENT THE INSERTION END OF THE METAL CANULA TAPERING INWARDLY TO SUBSTANTIALLY THE SAME DIAMETER AS THE METAL CANULA IN ORDER TO MAKE A SMOOTH, EVEN, AND EDGE-TIGHT CONTACT THEREWITH AND TERMINATING JUST SHORT OF THE FORWARD END OF SAID METAL CANULA, SAID PLASTIC CANULA DEFINING, AS INTEGRAL PARTS THEREOF, A FIRST PORTION OF SUBSTANTIALLY UNIFORM OUTER CROSS-SECTION AND WALL THICKNESS EXTENDING REARWARDLY FROM SAID FORWARD END, AN OUTWARDLY TAPERING SECOND PORTION OF REARWARDLY INCREASING WALL THICKNESS, EXTENDING REARWARDLY FROM SAID FIRST PORTION, AN ENLARGED RECESS ADJACENT SAID SECOND PORTION IN COMMUNICATION WITH THE INTERIOR OF SID CANULA AND SIDEWARDLY EXTENDING FINGER HOLDING MEANS, REARWARD OF SAID FIRST PORTION, SAID RECESS DEFINING A SEAT FOR CONNECTION WITH OTHER TUBINGS, SYRINGES, AND THE LIKE.