Sixty term parturients scheduled to have elective cesarean section were randomly allocated into three groups to receive either 20 mL 2 % articaine ( Group A ) , 10 mL 2 % articaine + 10 mL 0.75 % ropivacaine ( Group AR ) or 20 mL 0.75 % ropivacaine ( Group R ) via lumbar epidural catheter .