Volumes anestésicos efetivos no bloqueio do nervo isquiático: comparação entre as abordagens parassacral e infraglútea-arabiceptal com bupivacaína a 0, 5 por cento com adrenalina e ropivacaína a 0, 5 por cento / Volúmenes anestésicos efectivos en el bloqueo del nervio isquiático: comparación entre los abordajes parasacral e infraglúteo-parabicipital con bupivacaína a 0, 5 por ciento con adrenalina y ropivacaína a 0, 5 por ciento / Effective anesthetic volumes in sciatic nerve block: comparison between the parasacral and infragluteal-parabiceps approaches with 0, 5 percent bupivacaine with adrenaline and 0, 5 percent ropivacaine

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 por cento ou bupivacaína a 0,5 por cento 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 por cento: 14,9 - 20,8) e da bupivacaína 16,4 mL (IC 95 por cento: 12,3 - 21,9). Na abordagem infraglútea-parabiceptal o volume efetivo médio da ropivacaína foi 21,8 mL (IC 95 por cento: 18,7 - 25,5) e bupivacaína 20,4 mL (IC 95 por cento: 18,6 - 22,5). Volumes foram significativamente menores (p < 0,01) na abordagem parassacral comparativamente à infraglútea-parabiceptal. Na estimativa da regressão de Probits para volumes efetivos em 95 por cento dos pacientes, os volumes na abordagem parassacral foram 21,8 mL para ropivacaína e 20,5 mL para bupivacaína; e na infraglútea- parabiceptal foram 27,2 mL na ropivacaína e 25,5 mL na bupivacaína. O volume efetivo em 99 por cento dos pacientes no BNI parassacral para ropivacaína foi 24 mL e para bupivacaína 22,5 mL; e 29,9 mL de ropivacaína e 28,0 mL de bupivacaína no grupo infraglúteoparabiceptal. CONCLUSÕES: Foram necessários volumes significativamente menores na abordagem parassacral do BNI comparativamente à abordagem infraglúteaparabiceptal, mas os volumes anestésicos não diferiram entre os AL.

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 percent ropivacaine or 0.5 percent 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 percent CI: 14.9-20.8) and of bupivacaine it was 16.4 mL (95 percent CI: 12.3-21.9). In the infragluteal-parabiceps approach, the mean effective volume of ropivacaine was 21.8 mL (95 percent CI: 18.7-25.5), and that of bupivacaine was 20.4 mL (95 percent 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 percent 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 percent 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.

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 por ciento o bupivacaína a 0,5 por ciento 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 por ciento: 14,9 - 20,8) y el de la bupivacaína 16,4 mL (IC 95 por ciento: 12,3 - 21,9). En el abordaje infraglúteo-parabicipital el volumen efectivo promedio de la ropivacaína fue 21,8 mL (IC 95 por ciento: 18,7 - 25,5) y bupivacaína 20,4 mL (IC 95 por ciento: 18,6 - 22,5). Los volúmenes fueron significativamente menores (p < 0,01) en el abordaje parasacral al compararlos con el infraglúteo-parabicipital. En la estimativa de la regresión de Probits para volúmenes efectivos en un 95 por ciento de los pacientes, los volúmenes en el abordaje parasacral fueron 21,8 mL para la ropivacaína y 20,5 mL para la bupivacaína; y en el infraglúteo-parabicipital fueron 27,2 mL en la ropivacaína y 25,5 mL en la bupivacaína. El volumen efectivo en un 99 por ciento de los pacientes, en el BNI parasacral, para la ropivacaína fue 24 mL y para la bupivacaína 22,5 mL; y 29,9 mL de ropivacaína y 28,0 mL de bupivacaína en el grupo infraglúteoparabicipital. CONCLUSIONES: Se hicieron necesarios volúmenes significativamente menores en el abordaje parasacral del BNI al compararlos con el abordaje ...

[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]. / 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%

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 microg.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.

Ultrasound-guided obturator nerve block: a preliminary report of a case series.

BACKGROUND AND OBJECTIVES: Obturator-nerve block improves analgesia for knee surgery. Traditional techniques rely on surface landmarks, which can be variable and result in excessive performance times and multiple needle passes. The objective of this study was to evaluate a novel ultrasound-guided technique for localizing the obturator nerve. METHODS: A total of 22 patients undergoing anterior cruciate ligament repair had ultrasound-guided obturator-nerve blocks. Needles were directed under real-time ultrasound guidance. Endpoint for injection consisted of identifying contact of the tip of an insulated needle to nerve confirmed by adductor muscles' contraction. Local anesthetic was injected, and block was evaluated within 30 minutes. After that, ultrasound-guided sciatic-femoral blocks were placed for surgical purposes. Data collected included: time required for nerve identification, minimum stimulating current, number of attempts for correct identification, preblock and postblock adductor muscles' strength, sensory-nerve block, and quality of surgical anesthesia. RESULTS: In 91% of cases, the obturator nerve was correctly identified on first attempt within 30 +/- 23 seconds, as a hyperechoic flat or lip-shaped structure with internal hypoechoic dots. Minimal intensity of current to nerve stimulation was 0.30 +/- 0.08 mA. All patients exhibited decreases in adductor strength. Sensory territories were variable, with no cutaneous distribution in 32% of the patients. Small-dose opioid supplementation was required in 14% of the patients, but none required general anesthesia to complete surgery. CONCLUSIONS: These preliminary data suggest that ultrasound-guided obturator-nerve identification and block are technically easy and highly successful.