Radicular acute pain after epidural anaesthesia with the technique of loss of resistance with normal saline solution

Epidural anaesthesia using the loss of resistance to saline technique, without air, was successfully performed in a 65-year-old man scheduled for elective vascular surgery of the right leg. Epidural catheterisation was uneventful. Fifteen minutes after the initial dose of plain 0.5% bupivacaine, the patient experienced severe pain in his lower abdomen and legs which coincided with a supplementary injection of 2 ml bupivacaine and 50 microgram fentanyl, and a change from the lateral to the supine position. General anaesthesia was induced and CT and MRI scans were performed showing trapped air in the epidural space at the L4 level causing compression of the thecal sac. After excluding other causes, the spontaneous entry of air through the Tuohy needle was thought to be the most likely explanation for this complication. The patient recovered uneventfully.