Minimal Effective Dose of Hyperbaric Spinal Bupivacaine for Saddle Block

The optimal anesthetic technique would provide excellent operating conditions, rapid recovery, early discharge, no postoperative side effects, and high patient's satisfaction. In addition to increasing the quality and decreasing the costs of the anesthetic services (1). Selective spinal anesthesia (SSA) -spinal block with minimal effective doses for a specific type of surgery - has become very popular technique) 2(for some orthopedic and gynecological surgeries [3-9]. Saddle anesthesia is a SSA directs a small bolus of hyperbaric local anesthetic, towards S4-S5 and coccygeal nerve roots (11), and is commonly utilized for perianal surgeries (11-14). Hyperbaric bupivacaine has been safely, replaced hyperbaric Lidocaine for saddle block (11, 12). Although Saddle blocks at different low doses of hyperbaric bupivacaine (1.5- 4 mg) have been used previously for mi¬nor perianal surgeries (11, 13, 14), the optimal effective dose has yet to be determined. The objective of this study is to determine the minimal effective dose of hyperbaric spinal bupivacaine required to induce a reliable and satisfactory saddle block for perianal surgeries (using a modified Dixon's up-and-down method.