Abstract

The effects of total dose, volume, and concentration of glucose-free bupivacaine in spinal anesthesia were investigated in a double-blind study in 60 men undergoing transurethral surgery. The patients were randomly divided into six groups, receiving 10, 15, or 20 mg, respectively, in either a 0.5% or a 0.75% solution. The longest duration of analgesia (measured at L5 level) and complete motor blockade was obtained with 15 to 20 mg of either solution of bupivacaine, at 4 and 3 hours, respectively. Regardless of concentration of the bupivacaine solution, 10 mg was statistically significantly shorter-acting than 15 and 20 mg, between which no statistically significant differences were found. Systolic and diastolic blood pressures and heart rate decreased 5 to 10% in all groups, taking into account that nine patients were treated for hypotension and/or bradycardia. Post-lumbar puncture headache was not observed in any patient. The quality of spinal anesthesia with glucose-free bupivacaine seems to be related more to the total dose than to the volume or concentration of the solution.