Ultrasound‐guided approach to nerves (direct vs. tangential) and the incidence of intraneural injection: a cadaveric study

Abstract

This study evaluated the incidence of nerve puncture and intraneural injection based on the needle approach to the nerve (direct vs. tangential). Two expert operators in regional anaesthesia performed in-plane ultrasound-guided nerve blocks (n = 158) at different levels of the brachial plexus in cadavers, aiming either directly for the nerve (n = 77) or tangentially inferior to the nerve (n = 81). After reaching the outer limit of the nerve, the needle was intentionally advanced approximately 1 mm in both approaches, and 0.2-0.5 ml of saline was injected. Each operator classified (in real time) the needle tip and injectate as intraneural or not. Video clips showing the final position of the needle and the injection were evaluated in the same manner by seven independent expert observers who were blinded to the aims of this study. In addition, 20 injections were performed with ink for histological evaluation. Intraneural injections of saline were observed by the operator in 58% (45/77) of cases using the direct approach and 12% (10/81) of cases using the tangential approach (p < 0.001). The independent observers agreed with the operator in a substantial number of cases (Cohen's kappa index 0.65). Histological studies showed intraneural spread in 83% (5/6) of cases using the direct approach and in 14% (2/14) of cases using the tangential approach (p = 0.007). No intrafascicular injections were observed. There was good agreement between the operators' assessment and subsequent histological evaluation (Cohen's kappa = 0.89). Simulation of an unintentional/accidental advancement of the needle 'beyond the edge' of the nerve suggests significantly increased risk of epineural perforation and intraneural injection when a direct approach to the nerve is used, compared with a tangential approach.

Ultrasound-guided block and the incidence of intraneural injection

“…We appreciate Szerb and Kwesi Kwofie's comments on our recent paper [1]. We would like to emphasise that our study was a simulation of inadvertent needle advancement and subsequent injection, and does not reflect the needle approach used in clinical practice.…”

“…Ultrasound-guided block and the incidence of intraneural injection Sermeus et al suggested that a tangential approach to needle/nerve contact "should be included in algorithms for performing peripheral nerve block in order to prevent puncture and intraneural injection" [1]. We share their concerns with regard to the risk of inadvertent needle trauma and intraneural injection, and would like to invite the authors to reply to some observations we have about their study.…”

Electron microscopic examination of needles used in infraclavicular brachial plexus block

“…In a cadaver study of upper extremity blocks administered under ultrasound guidance, Sermeus et al [17] found the incidence of intraneural injection higher in procedures performed with a direct approach with ultrasonographic guidance to the target nerve compared to those performed with a tangential approach. In the current study, the possibility of needle contact with the brachial plexus was increased in Group 2, where local anesthetic agents were administered at 2, 6 and 9 o'clock levels of the subclavian artery.…”

Modelo artesanal de treinamento para acesso vascular ecoguiado em adaptação de gel balístico

“…Vários outros modelos já foram relatados como o uso de água e gelatina/ágar 9 , Blue Phantom™ 10 e os moldes que utilizam produtos orgânicos, como modelo animal 6,7 . Por outro lado, para ser considerado ideal, o simulador de ultrassom deve possuir a ecogenicidade comparável a dos tecidos humanos 6,7,9 , estar rapidamente disponível 7 , ter baixo custo 6 , possibilidade de ser utilizado repetidamente 6,7,9,10 , promover um feedback tátil 6,7,9 , manter a agulha estática 6,7,9,10 , não deixar evidente o caminho da agulha e não causar exposição a agentes nocivos à saúde 6,7,9,[10][11][12][13] . Todas essas características puderam ser observadas no modelo proposto com adaptação de gel balístico.…”