Learning curve for the ultrasound anatomy of the brachial plexus in the axillary region.

BACKGROUND AND OBJECTIVES: Proficiency in ultrasound-guided blocks demands four skills: recognition of the ultrasound anatomy, capacity to generate images, aligning the needle with the ultrasound beam, and recognizing the dispersion of the local anesthetic. The objective of this study was to construct and evaluate learning curves for image generation and ultrasound identification of the neurovascular structures in the axilla. METHODS: Seven Anesthesiology residents received theoretical and practical notions on the basic principles of ultrasound and the ultrasound anatomy of the axillary region with the objective to identify the terminal branches of the brachial plexus and axillary vessels. Each resident performed six exams. The accuracy and the time to identify the structures were evaluated. The success rate of each exam was calculated. Simple linear regression evaluated the time necessary to identify each structure in relation to the number of the exam. RESULTS: The axillary vessels were identified in 100% of the exams. The median nerve was identified in 83% of the cases from the first to the fifth exams. The radial nerve was identified in 100% of the exams. The ulnar nerve was identified in 67% of the cases in the first exam, and in 83% of the cases from the second to the fifth exams. The musculocutaneous nerve was identified in 50% of the cases in the first exam and in 83% of the cases in the fourth and fifth exams. All structures were identified correctly on the sixth exam. The mean time for the correct identification of the structures decreased considerably from the first to the sixth exam (r = - 0.37). CONCLUSIONS: Learning progression required the memorization of the ultrasound anatomy of the axillary region and acquisition of manual ability, and increasing success rates were associated with a significant reduction in the time to identify the structures.

Curva de aprendizado da sonoanatomia do plexo braquial na região axilar / Learning curve for the ultrasound anatomy of the brachial plexus in the axillary region / Curva de aprendizaje de la sonoanatomía del plexo braquial en la región axilar

JUSTIFICATIVA E OBJETIVOS: A proficiência em bloqueios guiados por ultrassom exige quatro habilidades: reconhecimento da sonoanatomia, capacidade de geração de imagens, alinhamento da agulha ao feixe ultrassonográfico e reconhecimento da dispersão do anestésico local. O objetivo deste estudo foi construir e avaliar curvas de aprendizado da geração de imagens e identificação ultrassonográfica das estruturas neurovasculares axilares. MÉTODO: Sete médicos em especialização em Anestesiologia receberam noções teóricas e práticas sobre princípios básicos da ultrassonografia e sonoanatomia axilar visando identificar ramos terminais do plexo braquial e vasos axilares. Cada um dos ME realizou seis exames. Foram avaliados a acurácia e o tempo transcorrido para identificação das estruturas. Em cada exame foram calculadas taxas de sucesso. Regressão linear simples avaliou o tempo para identificação de cada estrutura em relação ao número do exame. RESULTADOS: Os vasos axilares foram identificados em 100% dos exames. O nervo mediano foi identificado em 83% dos exames entre o primeiro e quinto. O nervo radial foi identificado em 100% dos exames. O nervo ulnar foi encontrado em 67% dos casos no primeiro exame e em 83% dos casos do segundo ao quinto procedimento. O nervo músculo-cutâneo foi localizado em 50% dos casos no primeiro exame, em 83% no quarto e no quinto exames. Todas as estruturas foram corretamente detectadas no sexto exame. O tempo médio para identificação das estruturas diminuiu significativamente entre o primeiro e sexto exames (r = - 0,37). CONCLUSÕES: A memorização sonoanatômica axilar e a aquisição de habilidade manual de exame ultrassonográfico foram obrigatórias para progressão do aprendizado e taxas de sucesso crescentes se associaram com redução significativa do tempo para identificação das estruturas.

BACKGROUND AND OBJECTIVES: Proficiency in ultrasound-guided blocks demands four skills: recognition of the ultrasound anatomy, capacity to generate images, aligning the needle with the ultrasound beam, and recognizing the dispersion of the local anesthetic. The objective of this study was to construct and evaluate learning curves for image generation and ultrasound identification of the neurovascular structures in the axilla. METHODS: Seven Anesthesiology residents received theoretical and practical notions on the basic principles of ultrasound and the ultrasound anatomy of the axillary region with the objective to identify the terminal branches of the brachial plexus and axillary vessels. Each resident performed six exams. The accuracy and the time to identify the structures were evaluated. The success rate of each exam was calculated. Simple linear regression evaluated the time necessary to identify each structure in relation to the number of the exam. RESULTS: The axillary vessels were identified in 100% of the exams. The median nerve was identified in 83% of the cases from the first to the fifth exams. The radial nerve was identified in 100% of the exams. The ulnar nerve was identified in 67% of the cases in the first exam, and in 83% of the cases from the second to the fifth exams. The musculocutaneous nerve was identified in 50% of the cases in the first exam and in 83% of the cases in the fourth and fifth exams. All structures were identified correctly on the sixth exam. The mean time for the correct identification of the structures decreased considerably from the first to the sixth exam (r = - 0.37). CONCLUSIONS: Learning progression required the memorization of the ultrasound anatomy of the axillary region and acquisition of manual ability, and increasing success rates were associated with a significant reduction in the time to identify the structures.

JUSTIFICATIVA Y OBJETIVOS: El desempeño en bloqueos guiados por ultrasonido exige cuatro habilidades: reconocimiento de la Sonoanatomía, capacidad de generación de imágenes, alineación de la aguja al haz ultrasonográfico y reconocimiento de la dispersión del anestésico local. El objetivo de este estudio fue construir y evaluar curvas de aprendizaje de la generación de imágenes e identificación ultrasonográfica de las estructuras neurovasculares axilares. MÉTODO: Siete médicos en especialización en Anestesiología recibieron nociones teóricas y prácticas sobre principios básicos de la ultrasonografía y sonoanatomía axilar, para identificar ramas terminales del plexo braquial y vasos axilares. Cada ME realizó seis exámenes. Fueron evaluados la exactitud y el tiempo transcurrido para la identificación de las estructuras. Se calcularon las tasas de éxito en cada examen. La regresión lineal simple evaluó el tiempo para la identificación de cada estructura con relación al número del examen. RESULTADOS: Los vasos axilares fueron identificados en 100% de los exámenes. El nervio mediano fue identificado en un 83% de los exámenes entre el primero y el quinto. El nervio radial fue identificado en 100% de los exámenes. El nervio cubital fue identificado en un 67% de los casos en el primer examen y en un 83% de los casos del segundo al quinto procedimiento. El nervio musculocutáneo fue identificado en un 50% de los casos en el primer examen, en un 83% en el cuarto y en el quinto exámenes. Todas las estructuras fueron correctamente identificadas en el sexto examen. El tiempo promedio para la identificación de las estructuras se redujo significativamente entre el primer y el sexto examen (r = - 0,37). CONCLUSIONES: La memorización sonoanatómica axilar y la adquisición de habilidad manual de examen ultrasonográfico, fueron obligatorias para la progresión del aprendizaje y para que las...