A novel catheter apparatus for use in delivering an anesthetic agent or other fluid medicament to the portion of subcutaneous tissue through which a catheter device has been inserted into a patient, thereby allowing the catheter device to be retracted without causing pain or discomfort to the patient. The catheter device has an indwelling cannula adapted for insertion through subcutaneous tissue into a patient's body. A cylindrical sheath is placed on the cannula so as to be positioned within the subcutaneous tissue once the cannula has been inserted into the body. The cylindrical sheath has formed therein a lumen into which the anesthetic agent or other fluid medicament can be delivered via a hub that is disposed on the catheter apparatus. The cylindrical sheath has formed therein a plurality of one-way slit valves. The one-way slit valves permit the anesthetic agent or fluid medicament to be delivered to the surrounding subcutaneous tissue, and also prevent any bodily fluids from entering the lumen. In one embodiment the cylindrical sheath is permanently mounted to the cannula. In another embodiment the cylindrical sheath is detachably mountable to the cannula. In yet another embodiment, the lumen is formed within the outer wall of the cannula and the one-way slits are formed through the outer wall.