Revista Brasileira de Anestesiologia (Oct 2009)
Volumes anestésicos efetivos no bloqueio do nervo isquiático: comparação entre as abordagens parassacral e infraglútea-arabiceptal com bupivacaína a 0,5% com adrenalina e ropivacaína a 0,5% Volúmenes anestésicos efectivos en el bloqueo del nervio isquiático: comparación entre los abordajes parasacral e infraglúteo-parabicipital con bupivacaína a 0,5% con adrenalina y ropivacaína a 0,5% Effective anesthetic volumes in sciatic nerve block: comparison between the parasacral and infragluteal-parabiceps approaches with 0.5% bupivacaine with adrenaline and 0.5% ropivacaine
Abstract
JUSTIFICATIVA E OBJETIVOS: O volume e a massa das soluções de anestésico local (AL) influenciam a taxa de sucesso dos bloqueios periféricos. Desta forma, o objetivo principal do estudo foi determinar os volumes de anestésico local para o bloqueio do nervo isquiático (BNI) nas abordagens parassacral e infraglútea-parabiceptal. MÉTODO: Cento e um pacientes foram alocados aleatoriamente em 4 grupos e submetidos ao BNI nas abordagens infraglútea-parabiceptal ou parassacral, utilizando ropivacaína a 0,5% ou bupivacaína a 0,5% com adrenalina 5 µg.mL-1. Sucesso foi definido como bloqueio sensitivo e motor completo do nervo isquiático 30 minutos após a injeção do AL. Os volumes foram calculados pelo método up-and-down. RESULTADOS: Na abordagem parassacral o volume efetivo médio da ropivacaína foi 17,6 mL (IC 95%: 14,9 - 20,8) e da bupivacaína 16,4 mL (IC 95%: 12,3 - 21,9). Na abordagem infraglútea-parabiceptal o volume efetivo médio da ropivacaína foi 21,8 mL (IC 95%: 18,7 - 25,5) e bupivacaína 20,4 mL (IC 95%: 18,6 - 22,5). Volumes foram significativamente menores (p JUSTIFICATIVA Y OBJETIVOS: El volumen y la masa de las soluciones de anestésico local (AL), influyen en la tasa de éxito de los bloqueos periféricos. Así, el objetivo principal del estudio fue determinar los volúmenes de anestésico local para el bloqueo del nervio isquiático (BNI) en los abordajes parasacral e infraglúteoparabicipital. MÉTODO: Ciento y un pacientes se ubicaron aleatoriamente en 4 grupos y fueron sometidos al BNI para los abordajes infraglúteoparabicipital o parasacral, utilizando ropivacaína a 0,5% o bupivacaína a 0,5% con adrenalina 5 µg.mL-1. El éxito se definió como bloqueo sensitivo y motor completo del nervio isquiático 30 minutos después de la inyección del AL. Los volúmenes se calcularon a través del método up-and-down. RESULTADOS: En el abordaje parasacral, el volumen efectivo promedio de la ropivacaína fue de 17,6 mL (IC 95%: 14,9 - 20,8) y el de la bupivacaína 16,4 mL (IC 95%: 12,3 - 21,9). En el abordaje infraglúteo-parabicipital el volumen efectivo promedio de la ropivacaína fue 21,8 mL (IC 95%: 18,7 - 25,5) y bupivacaína 20,4 mL (IC 95%: 18,6 - 22,5). Los volúmenes fueron significativamente menores (p BACKGROUND AND OBJECTIVES: The volume and mass of local anesthetics (LA) affect the success rate of peripheral nerve blocks. Thus, the main objective of this study was to determine the volumes of local anesthetics in parasacral and infragluteal-parabiceps sciatic nerve block (SNB). METHODS: One hundred and one patients undergoing infragluteal-parabiceps or parasacral SNB with 0.5% ropivacaine or 0.5% bupivacaine with 5 µg.mL-1 of adrenaline were randomly divided into 4 groups. Success was defined as complete sensitive and motor blockades of the sciatic nerve 30 minutes after the administration of the LA. Volumes were calculated by the up-and-down method. RESULTS: In the parasacral approach, the mean effective volume of ropivacaine was 17.6 mL (95% CI: 14.9-20.8) and of bupivacaine it was 16.4 mL (95% CI: 12.3-21.9). In the infragluteal-parabiceps approach, the mean effective volume of ropivacaine was 21.8 mL (95% CI: 18.7-25.5), and that of bupivacaine was 20.4 mL (95% CI: 18.6-22.5). Volumes were significantly lower (p < 0.01) in the parasacral than in the infragluteal-parabiceps approach. In Probit regression, the estimated effective volume in 95% of the patients in the parasacral approach was 21.8 mL for ropivacaine, and 20.5 mL for bupivacaine; in the infragluteal-parabiceps approach the volumes were 27.2 mL for ropivacaine and 25.5 mL for bupivacaine. The effective volume in 99% of the patients in parasacral SNB was 24 mL for ropivacaine, and 24 mL for bupivacaine; and in the infragluteal-parabiceps approach, 29.9 mL for ropivacaine, and 28.0 mL for bupivacaine. CONCLUSIONS: In sciatic nerve block, significantly smaller volumes were necessary in the parasacral than in the infragluteal-parabiceps approach, but volumes did not differ between both LAs.
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