Duración de bloqueo axilar con mepivacaína 1.5% en pacientes con insuficiencia renal crónica programados para fístula arteriovenosa. Estudio casos-controles / Axillary brachial plexus block duration with mepivacaine in patients with chronic renal failure. Case-control study

Introducción. El bloqueo del plexo braquial para la creación de fístula arteriovenosa (FAV) ha demostrado buenos resultados, si bien algunos autores han evidenciado una duración del bloqueo inferior al de los individuos sanos, probablemente por cambios en el flujo arterial regional. Nuestro objetivo fue evaluar la duración del bloqueo axilar con mepivacaína al 1,5 % en pacientes con insuficiencia renal crónica programados para FAV y compararlo con controles sanos. Métodos. Se incluyó a pacientes con insuficiencia renal crónica en hemodiálisis, llevados por primera vez para la creación de una FAV (GIRC). Se compararon con pacientes sin insuficiencia renal (GC), con características antropométricas similares; todos bajo bloqueo axilar ecoguiado con 20mL de mepivacaína al 1,5%. Se evaluaron el tiempo de latencia, el flujo y el diámetro de la arteria humeral pre y posbloqueo, así como la duración del bloqueo. Resultados. Se incluyó a 23 pacientes (GIRC: 12 y GC: 11). No se observaron diferencias en la latencia (GIRC: 13±5min vs. GC: 12,2±3min, p=0,477) ni en la duración del bloqueo (GIRC: 227±43min vs. GC: 229±27min, p=0,781). El flujo pre y posbloqueo fue significativamente menor en el GIRC (prebloqueo: GIRC: 52±21ml/min, GC: 100±62ml/min, p=0,034, y posbloqueo: GIRC: 130±57ml/min y GC: 274±182ml/min, p=0,010). No existió una correlación significativa entre la duración y el flujo arterial de la extremidad prebloqueo (rho de Spearman: 0,106; p=0,657) ni posbloqueo (rho de Spearman: 0,267; p=0,254). Conclusión. La duración del bloqueo axilar con mepivacaína al 1,5% en pacientes con insuficiencia renal crónica llevados por primera vez para creación de fístula arteriovenosa no es menor con respecto al grupo control y el flujo vascular como variable hemodinámica de la extremidad bloqueada no parece desempeñar un papel importante en la duración del mismo (AU)

Introduction. Regional anaesthesia is commonly preferred for arteriovenous fistula (AVF) creation. Previous studies suggest a shorter block duration in patients with chronic renal failure, maybe because of the changes in regional blood flow. The aim of our study was to evaluate the duration of the axillary block with 1.5% mepivacaine in patients with chronic renal failure scheduled for AVF compared with healthy controls. Methods. Patients scheduled for AVF creation for the first time (GIRC) were included. They were compared with patients without renal failure (GC), with similar anthropometric characteristics. Ultrasound-guided axillary blocks with 20mL of 1.5% mepivacaine were performed on all patients. We evaluated onset time, humeral artery diameter and blood flow before and after the block, as well as the block duration. Results. Twenty-three patients (GIRC: 12 and GC: 11) were included. No differences between groups were observed in block duration (GIRC: 227±43min vs GC: 229±27min; P=.781), or in onset time (GIRC: 13±5min vs GC: 12.2±3min; P=.477). The humeral blood flow before and after block was significantly lower in the GIRC (pre-block: GIRC: 52±21ml/min GC: 100±62ml/min; P=.034 and p ost block: GIRC: 130±57ml/min and GC: 274±182ml/min; P=.010). There was no significant correlation between the duration of the block and the preblock humeral blood flow (Spearman Rho: 0.106; P=.657) or the postblock humeral blood flow (Spearman Rho: 0.267; P=.254). Conclusion. The duration of the axillary block with 1.5% mepivacaine in patients with chronic renal failure was similar to that of the control patients. The duration of axillary brachial plexus block seems not to be related to changes in regional blood flow (AU)

Descripción del bloqueo del plexo braquial ecoguiado en espacio costoclavicular mediante abordaje medial y evaluación de la alteración en la perfusión regional secundaria / Medial approach of ultrasound-guided costoclavicular plexus block and its effects on regional perfussion

Introducción. El bloqueo infraclavicular ecoguiado en el espacio costoclavicular, situado entre la clavícula y la segunda costilla, pretende acceder a los troncos secundarios del plexo braquial cuando se hallan agrupados y laterales a la arteria axilar. Habitualmente se realiza mediante abordaje lateral, con la dificultad de la interposición de la apófisis coracoides y la dirección de la aguja hacia los vasos y la pleura. Un abordaje medial, es decir de interno a externo, evita estas estructuras. Tradicionalmente evaluamos el resultado del bloqueo infraclavicular mediante la valoración sensitiva y motora; no obstante, el bloqueo de las fibras simpáticas podría evaluarse objetivamente a través de los cambios en el flujo arterial, la temperatura cutánea y/o el índice de perfusión de la extremidad. Objetivo. Describir el bloqueo costoclavicular ecoguiado con acceso medial, evaluando su desarrollo mediante la evaluación motora, sensitiva y simpática. Materiales y métodos. Descripción inicial de la técnica y punción ecoguiada con contraste en cadáver, evaluando la distribución de un volumen de 20ml mediante tomografía computarizada (TC) y secciones sagitales de la pieza anatómica. Posteriormente, una fase clínica con inclusión de 11 pacientes a quienes se evaluó la instauración del bloqueo motor, sensitivo y simpático. Este último a través de la medición del flujo humeral, el índice de perfusión digital y la temperatura cutánea distal. Resultados. En el cadáver se realizó el acceso sin dificultades y se evidenció una adecuada distribución periclavicular de medio de contraste en la TC y en las secciones, alcanzando desde el espacio interescalénico hasta los troncos secundarios. El 91% de los pacientes presentó bloqueo quirúrgico a los 25 min. Todos los parámetros de bloqueo simpático evaluados aumentaron significativamente. El flujo arterial humeral aumentó de 108±86 a 188±141ml/min (p=0,05). La temperatura cutánea de 32,1±2 a 32,8±9°C (p=0,03) y el índice de perfusión de 4±3 a 9±5 (p=0,003). Conclusiones. El abordaje medial del bloqueo costoclavicular ecoguiado fue anatómicamente factible y con elevada eficacia clínica tras 20ml de mepivacaína al 1,5%. El bloqueo simpático obtenido puede evaluarse mediante los 3 parámetros estudiados (AU)

Introduction. Ultrasound-guided infraclavicular block in the costoclavicular space located between the clavicle and the first rib, reaches the secondary trunks when they are clustered together and lateral to the axillary artery. This block is most often performed through a lateral approach, the difficulty being finding the coracoid process an obstacle and guiding the needle towards the vessels and pleura. A medial approach, meaning from inside to outside, will avoid these structures. Traditionally the assessment of a successful block is through motor or sensitive responses but a sympathetic fibre block can also be evaluated measuring the changes in humeral artery blood flow, skin temperature and/or perfusion index. Objective. To describe the medial approach of the ultrasound-guided costoclavicular block evaluating its development by motor and sensitive response and measurement of sympathetic changes. Materials and methods. Description of the technique and administration of 20ml of contrast in a fresh cadaver model, evaluating the distribution with CT-scan and sagittal sections of the anatomic piece. Subsequently in a clinical phase, including 11 patients, we evaluated the establishment of motor, sensitive and sympathetic blocks. We evaluated the sympathetic changes reflected by humeral artery blood flow, skin temperature and distal perfusion index. Results. In the anatomical model the block was conducted without difficulties, showing an adequate periclavicular distribution of the contrast in the CT-scan and in sagittal sections, reaching the interscalenic space as far as the secondary trunks. Successful blocks were observed in 91% of patients after 25minutes. All the parameters reflecting sympathetic block increased significantly. The humeral artery blood flow showed an increase from 108 ± 86 to 188±141ml/min (P=.05), skin temperature from 32.1±2 to 32.8±9°C (P=.03) and perfusion index from 4±3 to 9±5 (P=.003). Conclusions. The medial approach of the ultrasound-guided costoclavicular block is anatomically feasible, with high clinical effectiveness using 20ml of 1.5% mepivacaine. The sympathetic block can be evaluated with all three parameters studied (AU)

Axillary brachial plexus block duration with mepivacaine in patients with chronic renal failure. Case-control study. / Duración de bloqueo axilar con mepivacaína 1,5% en pacientes con insuficiencia renal crónica programados para fístula arteriovenosa. Estudio casos-controles.

INTRODUCTION: Regional anaesthesia is commonly preferred for arteriovenous fistula (AVF) creation. Previous studies suggest a shorter block duration in patients with chronic renal failure, maybe because of the changes in regional blood flow. The aim of our study was to evaluate the duration of the axillary block with 1.5% mepivacaine in patients with chronic renal failure scheduled for AVF compared with healthy controls. METHODS: Patients scheduled for AVF creation for the first time (GIRC) were included. They were compared with patients without renal failure (GC), with similar anthropometric characteristics. Ultrasound-guided axillary blocks with 20mL of 1.5% mepivacaine were performed on all patients. We evaluated onset time, humeral artery diameter and blood flow before and after the block, as well as the block duration. RESULTS: Twenty-three patients (GIRC: 12 and GC: 11) were included. No differences between groups were observed in block duration (GIRC: 227±43min vs GC: 229±27min; P=.781), or in onset time (GIRC: 13±5min vs GC: 12.2±3min; P=.477). The humeral blood flow before and after block was significantly lower in the GIRC (pre-block: GIRC: 52±21ml/min GC: 100±62ml/min; P=.034 and p ost block: GIRC: 130±57ml/min and GC: 274±182ml/min; P=.010). There was no significant correlation between the duration of the block and the preblock humeral blood flow (Spearman Rho: 0.106; P=.657) or the postblock humeral blood flow (Spearman Rho: 0.267; P=.254). CONCLUSION: The duration of the axillary block with 1.5% mepivacaine in patients with chronic renal failure was similar to that of the control patients. The duration of axillary brachial plexus block seems not to be related to changes in regional blood flow.

Medial approach of ultrasound-guided costoclavicular plexus block and its effects on regional perfussion. / Descripción del bloqueo del plexo braquial ecoguiado en espacio costoclavicular mediante abordaje medial y evaluación de la alteración en la perfusión regional secundaria.

INTRODUCTION: Ultrasound-guided infraclavicular block in the costoclavicular space located between the clavicle and the first rib, reaches the secondary trunks when they are clustered together and lateral to the axillary artery. This block is most often performed through a lateral approach, the difficulty being finding the coracoid process an obstacle and guiding the needle towards the vessels and pleura. A medial approach, meaning from inside to outside, will avoid these structures. Traditionally the assessment of a successful block is through motor or sensitive responses but a sympathetic fibre block can also be evaluated measuring the changes in humeral artery blood flow, skin temperature and/or perfusion index. OBJECTIVE: To describe the medial approach of the ultrasound-guided costoclavicular block evaluating its development by motor and sensitive response and measurement of sympathetic changes. MATERIALS AND METHODS: Description of the technique and administration of 20ml of contrast in a fresh cadaver model, evaluating the distribution with CT-scan and sagittal sections of the anatomic piece. Subsequently in a clinical phase, including 11 patients, we evaluated the establishment of motor, sensitive and sympathetic blocks. We evaluated the sympathetic changes reflected by humeral artery blood flow, skin temperature and distal perfusion index. RESULTS: In the anatomical model the block was conducted without difficulties, showing an adequate periclavicular distribution of the contrast in the CT-scan and in sagittal sections, reaching the interscalenic space as far as the secondary trunks. Successful blocks were observed in 91% of patients after 25minutes. All the parameters reflecting sympathetic block increased significantly. The humeral artery blood flow showed an increase from 108 ± 86 to 188±141ml/min (P=.05), skin temperature from 32.1±2 to 32.8±9°C (P=.03) and perfusion index from 4±3 to 9±5 (P=.003). CONCLUSIONS: The medial approach of the ultrasound-guided costoclavicular block is anatomically feasible, with high clinical effectiveness using 20ml of 1.5% mepivacaine. The sympathetic block can be evaluated with all three parameters studied.