RESUMEN
PURPOSE: The purpose of this prospective, randomized, double-blind study was to compare anesthetic characteristics after two speeds of intrathecal injection of hyperbaric bupivacaine in elderly patients. METHODS: Fifty-six patients, aged ≥65 years, undergoing transurethral surgery under spinal anesthesia were allocated randomly to two groups according to rate of intrathecal injection of 2 ml hyperbaric bupivacaine 0.5%: group Fast (maximum possible rate; mean 0.38 ml/s) n = 26; group Slow (over 40 s; 0.05 ml/s), n = 25. Spinal blocks were administered in the lateral position. Data collection at different times included sensory level, motor block, hemodynamic changes, and occurrence of neurological symptoms. RESULTS: There was no significant difference between the groups regarding maximum sensory anesthetic level achieved (group Fast: T7 (T4-T10), median (range); group Slow T8 (T6-T10), P = 0.184); times (min) to reach (a) T10 sensory level (group Fast 5.3 ± 4.2 (mean ± SD), group Slow 8.0 ± 6.5, P = 0.093); (b) maximum sensory level (group Fast 11.6 ± 4.7; group Slow 13.6 ± 6.1, P = 0.199); and (c) 2-segment regression of anesthesia (group Fast 92.2 ± 29.6; group Slow 104.7 ± 36.1, P = 0.182). Degree and duration of motor block were similar (P = 0.947 and P = 0.895, respectively). Hemodynamic changes, ephedrine and atropine requirement, incidence of postoperative neurological symptoms after 24 h and 1 week were similar (all P > 0.05). CONCLUSIONS: An eightfold difference in speed of intrathecal injection of 0.5% hyperbaric bupivacaine did not affect the clinical characteristics of spinal anesthesia in elderly patients undergoing transurethral surgery.