RESUMEN
BACKGROUND: Pencil-point needle currently are used for spinal anesthesia because of an alleged lowered incidence of postdural puncture headache. Although the direction of the side hole is one of the important factors that might affect the level and the duration of anesthesia, those data are not readily available. The aim of this study was to assess if the side hole direction of pencil-point needle during hyperbaric tetracaine injection affects the level and the duration of anesthesia. METHODS: We induced spinal anesthesia in 80 young men presenting for elective orthopedic surgery. Patients were allocated randomly with the side hole direction of the 25 gauge pencil-point needle in one of the four directions; cephalad, caudad, left lateral, right lateral. Hyperbaric 0.5% tetracaine 15~17 mg (3 to 3.4 ml) was injected with the speed of 0.75 ml/sec. Maximum sensory block level, time to maximum sensory block level, duration of sensory block (2 segments regression time) were assessed by a blinded observer with the pin-prick test and degree of motor block were measured by Bromage motor scale. Data were analysed using the Kruskal-Wallis test followed by the Mann-Whitney U test and chi-square test as appropriate (SAS v. 6.04). RESULTS: Time to maximum sensory block level was significantly fast in group 'cephalad'. Other values have no statistical differences. Post-spinal headache was observed in one case in group 'caudad'. CONCLUSIONS: Using the pencil-point needle, the time to maximum sensory block level was fast in group cephalad but there were no differences in the maximum sensory block level and the duration of sensory block among the four groups.