ABSTRACT
BACKGROUND AND OBJECTIVE: The latency times of midfemoral sciatic nerve blocks vary greatly. This study investigated the correlation between the type of motor response to nerve stimulation on the one hand and latency and block efficacy on the other. PATIENTS AND METHODS: We enrolled 215 consecutive patients (184 women) undergoing orthopedic foot surgery. A tourniquet was applied above the malleolus. The puncture location was found by palpating to locate the groove between the vastus lateralis and biceps femoris muscles, at the mid-point of the line between the posterior edge of the greater trochanter muscle and the insertion of the biceps femoris muscle in the popliteal fossa. A solution of equal proportions (1:1) of 1.5% mepivacaine (with bicarbonate 1:10) and 0.75% levobupivacaine was injected at a dose of 0.45 mL x kg(-1) (maximum 40 mL) using a 10-cm needle. Nerve stimulation was applied at 100-300 ms, 02-0.4 mA, and 2 Hz. Latency was classified as response in less than 15 minutes, in 15 to 30 minutes, or later than 30 minutes. RESULTS: The evoked motor response was inversion in 30 patients, flexion or extension in 38, plantar flexion in 101, dorsiflexion in 37, and eversion in 9. Shorter latencies (15 minutes) were observed in all patients with inversion or flexion/extension and in 84 (83%) of the 101 patients with plantar flexion. Mid-range latencies were observed in 13% of those with a plantar flexion response and in 29.7% of those with dorsiflexion. All 9 patients with eversion and 17 (45.9%) of the 37 patients with dorsiflexion had the longest latencies. The surgical block was complete for all patients. CONCLUSIONS: This approach provides an effective block with minimum latency in patients who have a flexion or extension motor response in the foot and/or fingers, inversion, or plantar flexion, which assumes that the injection has reached the common trunk of the sciatic or tibial nerve. However, a longer latency is associated with a peroneal motor response, particularly eversion.
Subject(s)
Femoral Nerve/physiology , Foot/surgery , Nerve Block/methods , Adult , Aged , Aged, 80 and over , Anesthetics, Local/pharmacology , Bupivacaine/analogs & derivatives , Bupivacaine/pharmacology , Female , Femoral Nerve/anatomy & histology , Femoral Nerve/drug effects , Foot/anatomy & histology , Foot/innervation , Humans , Levobupivacaine , Male , Mepivacaine/pharmacology , Middle Aged , Movement , Orthopedic Procedures , Prospective Studies , Reaction Time/drug effects , Reaction Time/physiology , Young AdultABSTRACT
OBJETIVO: En el bloqueo anestésico mediofemoral delnervio ciático existe gran variabilidad en el tiempo delatencia. El objetivo de este trabajo fue relacionar el tipode respuesta motora a la neuroestimulación con el tiempode latencia y eficacia del bloqueo.PACIENTES Y MÉTODOS: Se incluyeron 215 pacientesconsecutivos (184 mujeres) para cirugía ortopédica delpie. Se empleó torniquete de isquemia supramaleolar. Ellugar de punción fue la depresión palpable entre músculosvasto lateral y bíceps femoral, en el punto medio dela línea que une el borde posterior del trocánter mayory la inserción del bíceps femoral en el pliegue poplíteo.Se inyectaron 0,45 mL.Kg-1 (máximo 40 mL), de unaproporción 1:1 de mepivacaína 1,5% (bicarbonatada1:10) y levobupivacaína 0,75%. Se empleó una aguja de10 cm de longitud. Los parámetros de neuroestimulaciónfueron 100-300 ms, 0,2-0,4 mA, 2 Hz. Según el tiempo delatencia se clasificó la respuesta como de menos de 15min, de 15-30 min ó más de 30 minutos.RESULTADOS: Las respuestas motoras encontradas fueroninversión (30 pacientes), flexo-extensión (38), flexiónplantar (101), flexión dorsal (37) y eversión (9). El tiempode latencia fue el menor (15 min) en todos los pacientescon inversión o flexo-extensión, y en 84/101 (83%) con flexiónplantar. Tuvieron latencia media (15-30 min) en 13%con flexión plantar y 29,7% con flexión dorsal. Tuvieronlatencia prolongada todos los pacientes con eversión (9 de9) y en 17/37 (45,9%) con flexión dorsal. El bloqueo quirúrgicofue completo en todos los pacientes.CONCLUSIONES: Con esta vía de abordaje se consigue unbloqueo eficaz y mínima latencia cuando la respuesta esflexo-extensión de pie y/o dedos, inversión o flexión plantar,que supone inyectar en el tronco común del ciático onervio tibial. Por contra la latencia prolongada se asocia auna respuesta motora peronea, especialmente la eversión(AU)
BACKGROUND AND OBJECTIVE: The latency times ofmidfemoral sciatic nerve blocks vary greatly. This studyinvestigated the correlation between the type of motorresponse to nerve stimulation on the one hand andlatency and block efficacy on the other.PATIENTS AND METHODS: We enrolled 215 consecutivepatients (184 women) undergoing orthopedic foot surgery.Atourniquet was applied above the malleolus. The puncturelocation was found by palpating to locate the groovebetween the vastus lateralis and biceps femoris muscles, atthe mid-point of the line between the posterior edge of thegreater trochanter muscle and the insertion of the bicepsfemoris muscle in the popliteal fossa. A solution of equalproportions (1:1) of 1.5% mepivacaine (with bicarbonate1:10) and 0.75% levobupivacaine was injected at a dose of0.45 mL·kg1 (maximum 40 mL) using a 10-cm needle.Nerve stimulation was applied at 100-300 ms, 0.2-0.4 mA,and 2 Hz. Latency was classified as response in less than 15minutes, in 15 to 30 minutes, or later than 30 minutes.RESULTS: The evoked motor response was inversion in30 patients, flexion or extension in 38, plantar flexion in101, dorsiflexion in 37, and eversion in 9. Shorter latencies(15 minutes) were observed in all patients with inversion orflexion/extension and in 84 (83%) of the 101 patients withplantar flexion. Mid-range latencies were observed in 13%of those with a plantar flexion response and in 29.7% ofthose with dorsiflexion. All 9 patients with eversion and 17(45.9%) of the 37 patients with dorsiflexion had the longestlatencies. The surgical block was complete for all patients...(AU)
