Identification of Epidural Space Description of New Technique

• A total of 60 consecutive ASA class 1& II patients of ages between 28-68 years scheduled for elective surgery under lumber epidural anesthesia or under general anesthesia with planned post-operative epidural analgesia were enrolled in this study.

Patients with known coagulation disorder, allergy to local anesthetics, skin lesions at the puncture side, or neuromuscular disease were not included.

Patients are placed in sitting position and American society of anesthesiologists standard monitors attached. After skin preparation, draping, and local anesthetic infiltration, an epidural Tuohy needle is introduced into intervertebral space at the level of L3-L4 up to the interspinous ligaments ( nearly 2cm mark on the needle). Fig 1 A3-way stopcock is connected to the hub of Tuohy needle with the in-line port of the stopcock attached to an air-filled 10 ml syringe. Using a 75 cm extension tube set the side port is connected to the Pressure Gauge Manometer held by the assistant. The stopcock is turned so that the needle is in direct continuity with both syringe and pressure Gage manometer. The syringe is used to create a 30 mm Hg pressure reading on the manometer, the stopcock then is turned into "open" to manometer and Tuohy needle and "close" to syringe.

With this 30 mm Hg pressure gradient between manometer and the tip of epidural needle, the needle is advanced slowly using both hands while monitoring the manometer reading and is stopped when the pressure changes ( the pressure usually drops by 5-10 mm Hg when the tip of the needle inters the epidural space ).

The 3-way is then removed and local anesthetic is injected for single shot epidural block or catheter is introduced in the conventional manner and secured by adhesive tap.

Procedure was performed by anesthetists of different levels of experience (consultant, specialist, resident).

Demographic data and type of surgery is recorded along with time of the technique, number of passes required to enter the epidural space, any false LOR, insertion difficulties, accidental dural puncture, or any other complication occurred.