After registration on the day of surgery patients were brought to the pre-anesthetic area where IV cannulation was performed and standard anesthetic monitors applied. Patients received intravenous sedation prior to placement of the spinal anesthetic at the discretion of the responsible consultant anesthesiologist. A spinal anesthetic was performed under standard aseptic conditions in the usual fashion. The choice of local anesthetic (either isobaric bupivacaine 0.5% or hyperbaric bupivacaine 0.5%.) used to perform the spinal anesthetic was at the discretion of the responsible consultant anesthesiologist.