An infusor system for administering medications to a venous blood vessel in the body of a patient. The infusor system includes a flexible, elongated delivery tube having opposite ends. One of the ends is couplable to a supply of liquid medication, which is remote from the venous blood vessel. The system further includes a delivery component coupled to the other end of the delivery tube. This delivery component is adaptable to be placed in confronting relationship with the venous blood vessel so that medication from said supply may be introduced directly into the venous blood vessel and distributed in the body of the patient. The infusor system further includes a pressure-altering device used for increasing intraabdominal pressure in the body of the patient. Sampling of venous blood from the meningorrhachidian vasculature is also possible.