[Sciatic nerve block. Description of a new posterior approach in the gluteal area]. / Bloqueo del nervio ciático. Descripción de un nuevo trayecto de abordaje posterior en el glúteo.

OBJECTIVE: To describe and assess the clinical usefulness of a new posterior approach for sciatic nerve block to the gluteal zone. PATIENTS AND METHODS: This prospective descriptive study of 40 adults undergoing lower limb surgery measured the difficulty, efficacy and success of the described sciatic nerve block. TECHNIQUE: the patient was placed in Sim's position for a posterior approach. A line was then drawn from the upper part of the iliac spine to the sacral hiatus. From the midpoint of that line, a second line of equal length, perpendicular to the first and medial, was then drawn. The end of that line was the point of puncture. The needle was inserted perpendicular to all planes. Mepivacaine 1.5% (0.3 ml/kg) was injected. RESULTS: The sciatic nerve was located upon the first attempt in 90% of the patients within 21.86 +/- 12.62 s. The block failed in 2.5%. Time taken to establish the block was 19.17 +/- 9.62 m. One transitory, mild complication occurred. No vascular puncture occurred. CONCLUSIONS: We describe a new approach for sciatic nerve block using only two points of osseous reference identified by palpation. The level of efficacy and safety is high.