[Spread of local anesthetic solutions in the thoracic epidural space]

The segmental spread of thoracic epidural analgesia was measured in 14 patients scheduled for elective surgery with ages ranging from 35 to 80 years. Epidural puncture was performed in the seventh or eighth thoracic intervertebral space using 17 gauge Tuohy needle with the patient in the left lateral position. The epidural space was identified using "loss of resistance technique". With the bevel of the needle pointing towards the head, 7-10 ml of 2% mepivacaine was injected at the rate of 1 ml.sec-1. Fifteen minutes after injection of anesthetic, the spinal segments anesthetized were determined by absence of cold sensation. A statistically significant correlation was found between age and a segmental dose (ml.seg-1) (r = -0.72), and between age and a segmental dose corrected by height (ml.seg-1.m-1) (r = -0.65).