ABSTRACT
Abstract Background and objectives: The current study aimed to determine the minimum effective volume (MEV) of bupivacaine 0.5% in 50% of patients for an ultrasound-guided retroclavicular approach to infraclavicular brachial plexus block. Methods: A total of 25 adult patients who were scheduled for upper limb surgery received an ultrasound-guided retroclavicular approach to infraclavicular brachial plexus block with bupivacaine 0.5%. The needle insertion point was posterior to the clavicle and the needle was advanced from cephalad to caudal. Block success was defined as a composite score of 14 at 30 min after local anesthetic (LA) injection. The minimum effective volume in 50% of patients was determined using the Dixon-Massey up-and-down staircase method. Minimum effective volume for a successful block in 95% of the patients was also calculated using logistic regression and probit transformation. Results: The minimum effective volume of bupivacaine 0.5% resulting in successful block in 50% of patients (MEV50) according to the up-and-down staircase method was found to be 9.6 mL (95% confidence interval (CI), 5.7-13.4). The calculated minimum effective volume required for a successful block in 95% of patients (MEV95) using the probit transformation and logistic regression analysis was 23.2 mL (95% CI, 18.8-36.7). Conclusions: The MEV50 of bupivacaine 0.5% for US-guided retroclavicular approach to infraclavicular brachial plexus block was 9.6 mL and the calculated MEV95 was 23.2 mL. Future studies are required for infraclavicular brachial plexus block with different approaches, other LA agents and different concentrations of bupivacaine.
Resumo Justificativa e objetivos: Determinar o volume mínimo efetivo (VE) de bupivacaína a 0,5% em 50% dos pacientes para uma abordagem retroclavicular guiada por ultrassom no bloqueio do plexo braquial por via infraclavicular. Métodos: Um total de 25 pacientes adultos agendados para cirurgia do membro superior receberam abordagem retroclavicular guiada por ultrassom para o bloqueio do plexo braquial por via infraclavicular com bupivacaína a 0,5%. O ponto de inserção da agulha foi posterior à clavícula e a agulha foi avançada de cefálica para caudal. O sucesso do bloqueio foi definido como um escore composto de 14 aos 30 min após a injeção do anestésico local. O VE em 50% dos pacientes foi determinado com o método de escalonamento progressivo-regressivo de Dixon-Massey. O VE para um bloqueio bem-sucedido em 95% dos pacientes também foi calculado com regressão logística e transformação probit. Resultados: O volume mínimo efetivo (VE50) de bupivacaína a 0,5% que resultou em bloqueio bem-sucedido em 50% dos pacientes, de acordo com o método de escalonamento progressivo-regressivo, foi de 9,6 ml (intervalo de confiança de 95%, IC 5,7-13,4). O cálculo do volume mínimo efetivo necessário para um bloqueio bem-sucedido em 95% dos pacientes (VE95) com a análise de transformação probit e regressão logística foi de 23,2 ml (IC 95%, 18,8-36,7). Conclusões: O VE50 de bupivacaína a 0,5% para abordagem retroclavicular guiada por US para o bloqueio do plexo braquial por via infraclavicular foi de 9,6 ml e o VE95 calculado foi de 23,2 ml. Estudos futuros são necessários para o bloqueio do plexo braquial por via infraclavicular com diferentes abordagens, outros anestésicos locais e diferentes concentrações de bupivacaína.
Subject(s)
Humans , Male , Female , Adult , Bupivacaine/administration & dosage , Ultrasonography, Interventional/methods , Brachial Plexus Block/methods , Anesthetics, Local/administration & dosage , Upper Extremity/surgery , Dose-Response Relationship, Drug , Middle AgedABSTRACT
Background: To determine the effective volume of a combination of bupivacaine and lignocaine for supraclavicular achial plexus block using ultrasonography (USG). Methods: This study is an intervention study to determine the minimum effective volume of a drug combination. The principle statistical method applied in this study is Staircase Up-down method as described by Dixon and Massey.([i]) Results: By using the log transformation of the data of required volume and outcome as successful or unsuccessful we have calculated EV 50 = 11ml and EV 90 = 14ml. Conclusion: Minimum Effective Volume in 90% individuals (MEV 90) for a combination of 0.25% bupivacaine and 1% lignocaine for ultrasound guided achial plexus block via supraclavicular approach is 14ml.
ABSTRACT
BACKGROUND: The aim of this study was to estimate the minimum effective volume (MEV) of 1.5% mepivacaine for ultrasound-guided supraclavicular block by placing the needle near the lower trunk of brachial plexus and multiple injections. METHODS: Thirty patients undergoing forearm and hand surgery received ultrasound-guided supraclavicular block with 1.5% mepivacaine. The initial volume of local anesthetic injected was 24 ml, and local anesthetic volume for the next patient was determined by the response of the previous patient. The next patient received a 3 ml higher volume in the case of the failure of the previous case. If the previous block was successful, the next volume was 3 ml lower. MEV was estimated by the Dixon and Massey up and down method. MEV in 95, 90, and 50% of patients (MEV95, MEV90, and MEV50) were calculated using probit transformation and logistic regression. RESULTS: MEV95 of 1.5% mepivacaine was 17 ml (95% confidence interval [CI], 13-42 ml), MEV90 was 15 ml (95% CI, 12-34 ml), and MEV50 was 9 ml (95% CI, 4-12 ml). Twelve patients had a failed block. Three patients received general anesthesia. Nine patients could undergo surgery with sedation only. Only one patient showed hemi-diaphragmatic paresis. CONCLUSIONS: MEV95 was 17 ml, MEV90 was 15 ml, and MEV50 was 9 ml. However, needle location near the lower trunk of brachial plexus and multiple injections should be performed.