This study examined anesthetic development and hemodynamic changes during two techniques of hyperbaric lidocaine administration through 27-gauge intrathecal catheters for continuous spinal anesthesia in 55 elderly patients undergoing transurethral prostatic resection. Twenty-five patients were randomly assigned to receive hyperbaric lidocaine 5% solution in a single bolus of 75 mg to achieve blockade to approximately T6, and 30 patients to receive hyperbaric lidocaine 2.5% solution in increments of 25 mg to achieve T6 or to a maximum of three doses. Hemodynamic measurements of arterial pressure, heart rate, cardiac output, stroke volume, and ejection fraction were made serially after the induction of spinal anesthesia. Anesthesia failed to spread beyond the sacral region in 9/25 (36%) patients in the single-dose group (SD), but was successfully induced in all patients given titrated doses (TD) at total doses of 50 mg (n = 15) (TD50) and 75 mg (n = 15) (TD75). The mean maximal level of sensory block in all three groups was comparable: T5, T4, and T6 in groups SD, TD50, and TD75, respectively. The onset and progression of sensory block were rapid and similar in the SD and TD50 groups, in contrast to a gradual, stepwise development of block in group TD75. Grade 3 motor block occurred in response to the first dose of 25 mg lidocaine in 7/30 (23%) patients receiving titrated doses, but the overall incidence of leg paralysis did not differ among the three groups by the end of lidocaine dosing. Mean arterial pressure (MAP) decreased significantly relative to baseline in all three groups.(ABSTRACT TRUNCATED AT 250 WORDS)