Many factors influence the distribution of local anesthetic solutions within the subarachnoid space. Among the factors which are under the control of the anesthesiologists, the effect of direction of bevel on spinal anesthetic or urologic
surgery,
with
ASA physical status 1. Patients were randomized into one of four groups, according to the direction of bevel(cephalad, caudad, up, down), With patient in the lateral decubitus position, dural puncture was performed in the midline at the L3-4
interspace
with a 23-gauge needle, and the patients were immediately turned to supine position, Local anesthetic solution in all patients was composed of 1.6 ml of 1% tetracaine and 1.6 ml of 10% dextrose, resulting 3.2 ml(16 mg) of 0.5% tetracaine,
Segmental
spread of analgesia was determined by pin-prick in the anterior axillary line. Duration of block and degree of motor block were measured by two segment regression time and Bromage scale, respectively. No difference was observed among four groups
in
the
onset time to maximal level of sensory block, two segment regression time, and degree of complete motor block of lower limbs. In caudal group, maximal level of sensory block was about 1.1-1.4 segments lower than other groups. But no statistical
significance was found, There were wide variations in the maximal level of sensory block(T11-T3), and time to reach this(5 min-35 min).
The present study indicates that the direction of bevel is unimportant in influencing anesthetic characteristics of spinal anesthesia and, it is difficult to predict accurately the onset time and the level which will be attained because there are
wide
individual variations in the spread of local anesthetics in subarachnoid space.
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