Double lumen cannula apparatus

A double lumen cannula apparatus for blood sampling comprising in combination a body member comprising a base and an extension projecting from said base, said extension having a frustoconical shaped portion;

• a cannula sheath of generally funnel shape having frustoconical portion of larger diameter than and coaxially surrounding that of said extension, said frustoconical portion of said sheath terminating at its reduced diameter end in a cylindrical tubular end portion;
• means affording an annular fluid-tight seal between said extension and said sheath;
• first conduit means traversing and having a fixed positional relationship with respect to said body member, said conduit means terminating in a tubular end portion spaced substantially coaxially within said reduced diameter tubular end portion of said sheath and having an end spaced a predetermined distance axially inwardly from the end of the surrounding reduced diameter sheath portion;
• cooperable abutment means on said body member and sheath defining said predetermined distance between said ends of said first conduit means and sheath;
• and second conduit means traversing said body member and opening into the space between said extension and the frustoconical portion of said sheath.