Fig. 2.  Initial and overall successful anesthesia at different doses of hyperbaric intrathecal bupivacaine. This bar chart differentiates success (induction) in the red bars (defined as a bilateral T6 sensory level to pinprick within 10 min of intrathecal drug administration) from success (operation) in the blue bars (defined as a successful initial sensory level with no additional epidural anesthetic required during surgery).