 Epidural wave form analysis EWA is very simple and reliable method which can substitue the LOR technique. If the epidural needle is located correctly in the epidural space, the investigators can observe a pulsatile wave and this pulsatile wave corresponds to arterial wave. Generally, sensitivity of EWA through needle is known to be superior to the sensitivity of EWA through catheter and most studies were focused on catheter EWA. 