COMPARISON OF GLUCOSE 7.5-PERCENT AND 0.75-PERCENT WITH OR WITHOUT PHENYLEPHRINE FOR TETRACAINE SPINAL-ANESTHESIA

Purpose: To investigate whether a marginally hyperbaric tetracaine sol ution with or without phenylephrine could produce consistent blocks as compared with a conventionally hyperbaric tetracaine solution injecte d at L(3-4) interspace with the patient in the lateral position. Metho ds: We studied 120 ASA I or II patients scheduled for elective surgery to the lower limb. Patients were randomly divided into four equal gro ups to receive spinal anaesthesia using tetracaine 0.5% in glucose 0.7 5% or 7.5%, with or without phenylephrine 0.125%. Neural block was ass essed in a double-blind manner by cold, pinprick, and touch sensation, and a modified Bromage scab after the injection of the study drug. Re sults: The median (lath, 90th percentiles) peak dermatomal level to pi nprick obtained by the solutions in glucose 0.75% was T-10 (L(1), T-5) which was lower than that obtained by the solution in glucose 7.5% ex tending to T-5(T-10, T-3) and T-5 (T-10, T,) with or without phenyleph rine, respectively (P < 0.0001). The addition of phenylephrine prolong ed the time to two-segment regression but did nor change the maximum e xtent of blocks. Conclusions: A marginally hyperbaric tetracaine with or without phenylephrine produced consistent blocks with spread restri cted to the lower thoracic segments when administered intrathecally at the L(3-4) interspace with the patient in the lateral position.