After written, informed, valid consent, and administration of five hundred millilitres of Ringer's lactate intravenously as a preload, epidural catheter will be inserted under aseptic conditions in an L2-L3 or L3-L4 space through 16 G Tuohy's needle. Epidural space will be identified through the loss-of-resistance technique. The catheter will be placed, cephaled, two spaces (3 to 4 cm) above the point of insertion.