[Anterior '3-in-1' blockade: partial, total or overdimensioned block? Correlation between anatomy, clinic and radio images.].

BACKGROUND AND OBJECTIVES Classic anterior 3-in-1 blockade has been questioned as to the anesthetic involvement of its three participant nerves: femoral, lateral cutaneous of thigh and obturator. This study aimed at evaluating the outcome of anterior 3-in-1 blockade through: single injection (G1), short catheters (G2) and long catheters (G3). 3-in-1 blockades identified as total or overdimensioned were additionally investigated by radio images. METHODS The identification of iliac subfascial space in 3-in-1 blockades with single injection or catheters has been made by loss of resistance to air. In several painful events, anesthetic volume has varied 30 to 40 mL and cranial catheters introduction was up to 18 cm in the iliac subfascial space. When clinical research would point to the involvement of the obturator nerve or other nerve additional to 3-in-1 blockade, investigation was complemented by radiographic or TC-Scan studies aiming at establishing correspondence with pelvic anatomy. RESULTS The involvement of lateral cutaneous of thigh and obturator nerves has not been constant, as opposed to the femoral nerve. No total 3-in-1 blockade with single injection (G1) was observed in our study, but rather 2-in-1, with eventual participation of the femoral branch of the genitofemoral nerve (2.5-in-1 blockade). However, when short catheters were used (G2), there has been 3-in-1 blockade in just one patient, while with long catheters (G3) introduced in the cephalad direction until 18 cm in the iliac subfascial space, three overdimensioned 3-in-1 blockades were recorded, with the additional involvement of common fibular nerve in two patients and tibial nerve in one patient. CONCLUSIONS In spite of the small sample size, single injection (G1) has always provided 2-in-1 or 2.5-in-1 blockade without the participation of the obturator nerve. With short catheters (G2) 3-in-1 blockade was classified as total in 6.6% of cases (one patient). With long catheters (G3), however, results seem to be more predictable as compared to the other groups, especially when the catheter reaches the lumbosacral paravertebral space, resulting in total 3-in-1 blockade in 20% of cases (3 patients) or more uncommonly, in overdimensioned 3-in-1 blockade in 13.2% of cases (2 patients).