Ultrasound Guided Local Anesthetic Field Block (A Five Step Procedure) for Open Inguinal Hernia Repair

Open Inguinal hernia repair is one of the commonest procedures performed worldwide. Still, there is no consensus regarding the optimum anesthesia technique for this surgery. General, spinal, epidural and local anesthesia techniques have all been used, each having its own advantages and disadvantages.

General anesthesia carries risks of possible airway complications, postoperative deterioration of cognitive function, sore throat, nausea, vomiting and prolonged period of immobilization with associated risk of deep vein thrombosis and longer hospital stay. Spinal anesthesia, although effective, is not without risk in patients with decompensated heart disease, recent head injury, convulsions and coagulopathies. Also spinal and epidural anesthesia have been associated with hemodynamic instability, vomiting, urinary retention, post-dural puncture headache, and backache.

Use of pre-incision infiltration of local anesthetics for field blocks has been found to be an effective adjunct as well as an alternative to spinal and general anesthesia in many studies. Combined with sedation or on its own, it offers less cardiovascular instability, early ambulation and effective post-operative pain control. Also, it has been found to reduce hospital costs by 50% and gives better patient satisfaction.

Harvey Cushing and William Halsted first described the inguinal field block in 1900. since then, its efficacy and advantages have been compared by many surgeons and anesthesiologists in a number of studies. Refinements and modifications in the technique still continue. In 1963, Joseph L Ponka described in great detail a seven step procedure of performing it in 837 patients successfully.

In 1994, Parvis and colleagues did a step by step technique for local anesthetic infiltration field block for open inguinal hernia repair.

Ultrasonography is a safe and effective form of imaging. Over the past two decades, ultrasound equipment has become more compact, of higher quality and less expensive. Ultrasounds have been used to guide needle insertion and a number of approaches to nerves and plexuses have been reported. A clear advantage of the technique is that ultrasound produces "living pictures" or "real-time" images. The identification of neuronal and adjacent anatomical structures (blood vessels, peritoneum, bone, organs) along with the needle is another advantage. Moreover, anatomical variability may be responsible for block failures, and ultrasound technology enabling direct visualization may overcome this problem. Sonographic visualization allows for the performance of extra-epineurial needle tip positioning and administration of local anesthetic avoiding intra-epineurial injection.

A modification to the technique performed by Parvis and colleagues will be tested in this study. Our modification will be performing the technique under ultrasound guidance and completely before skin incision, which, to the best of our knowledge, was not attempted in the literature before.

Local anesthesia administered before skin incision produces longer postoperative analgesia because local infiltration theoretically inhibits the build-up of local nociceptive molecules and, therefore, there is better pain control in the postoperative period.This study aims at evaluating success, efficacy, feasibility and safety of a simple five step ultrasound guided local anesthetic infiltration technique for unilateral open inguinal hernia repair and also to compare intraoperative and postoperative complications and pain control of the block with spinal anesthesia.