Capillary tube assembly

A kit comprising:

• a bodily invasive tube (200) that is a venous catheter (210′), and
• a detachable device for adding one or more channels to the bodily invasive tube (200) which detachable device comprises a capillary tube assembly (100) having a proximal (20) end and a distal (30) end and comprises:
• a thin walled capillary tube shaft (10) disposed with a capillary lumen (12) extending from an open proximal (20) end to an open distal (30) end, and
• a fluidic adapter (40) at the proximal (20) end in fluid connection the capillary tube lumen (12),
• wherein
• the capillary tube shaft (10) is adapted for dismountable insertion into a fluid-carrying lumen (212) of the bodily invasive tube (200) that is the venous catheter, such that the distal (30) tip of the capillary tube protrudes from the distal tip of the bodily invasive tube (200), and to maintains the flow function of the venous catheter,
• the adapter (40) is configured to provide fluidic access to the capillary tube lumen (12) that is fluidically isolated from access to the invasive tube lumen (212).