Fig. 1. The minimum local analgesic dose (MLAD) of intrathecal levobupivacaine was 1.35 mg (95% confidence interval, 1.25–1.45 mg) in group 10 ( A ), 1.63 mg (95% confidence interval, 1.51–1.76 mg) in group 5 ( B ), and 1.97 mg (95% confidence interval, 1.89–2.05 mg) in group 2.5 ( C ), as determined by the technique of up–down sequential allocation .