Incidence of intraneural needle insertion in ultrasound-guided femoral nerve block: A comparison between the out-of-plane versus the in-plane approaches / Incidencia de inserción intraneural en bloqueo femoral guiado por ecografía: comparación entre los enfoques en plano y fuera de plano

BACKGROUND: The optimal method of ultrasound-guided femoral nerve block (in-plane vs. out-of-plane) has not been established. We tested the hypothesis that the incidence of needle-nerve contact may be higher with out-of-plane than with in-plane needle insertion. METHODS: Forty-four patients with hip fracture (American Society of Anaesthesiologists physical status I-III) were randomized to receive the femoral block with an out-of-plane approach (needle inserted at a 45-60° angle 1 cm caudal to the midpoint of the ultrasound probe just above the femoral nerve) or with an in-plane technique (needle inserted 0.2-0.4 cm from the side of the probe lateral to the femoral nerve). Data collected included depth of needle insertion, response to nerve electric stimulation, and distribution of the injected volume in relation to the nerve (anterior vs. posterior, the latter assuming needle-nerve contact). The sensory block onset was tested at 20 min and block recovery and any neurologic symptoms were evaluated at 24 h. RESULTS: The incidence of needle-nerve contact was significantly higher with the out-of-plane approach (14/22 patients [64%]) than with the in-plane approach (2/22 patients [9%]) (p < 0.001) (OR = 17.5, 95% CI: 4-79). The rate of paraesthesia on crossing the fascia iliaca was similar in the two groups. All blocks uneventfully regressed; and no patient developed neurologic symptoms. CONCLUSIONS: Under the conditions of our study, needle-nerve contact during femoral nerve block occurs frequently with the out-of-plane approach. An in-plane approach results in an equally effective femoral block and less incidence of needle-nerve contact

ANTECEDENTES. No ha quedado establecido un método adecuado para el bloqueo femoral guiado por ecografía (en plano frente a fuera de plano). Probamos la hipótesis de que la incidencia del contacto entre la aguja y un nervio puede ser mayor en la inserción fuera de plano que en el abordaje en plano. MÉTODOS: Cuarenta y cuatro pacientes con fractura de cadera (estadio i-iii según la Sociedad Americana de Anestesiólogos) recibieron de manera aleatorizada un bloqueo femoral con un enfoque fuera de plano (inserción de la aguja en ángulo de 45-60° y 1 cm caudal a la sonda de ecografía sobre el nervio femoral) o con una técnica en plano (inserción de la aguja 0,2-0,4 cm desde el lado de la sonda lateral al nervio femoral). Entre los datos recopilados se incluían la profundidad de inserción de la aguja, la reacción a la estimulación nerviosa y la distribución del volumen inyectado en función del nervio (anterior comparado con posterior, este último con contacto entre la aguja y un nervio). Se analizó el inicio del bloqueo a los 20 min y se evaluaron la recuperación del bloqueo y los síntomas neurológicos después de 24 h. RESULTADOS: La incidencia del contacto entre la aguja y los nervios fue significativamente mayor con el enfoque fuera de plano (14/22 pacientes [64%]) que con el abordaje en plano (2/22 pacientes [9%]) (p < 0,001) (OR = 17,5 [95%]; IC: 4-79). El grado de parestesia en aponeurosis fue similar en ambos grupos. Se revirtieron todos los bloqueos sin incidentes; ningún paciente desarrolló síntomas neurológicos. CONCLUSIONES: En las condiciones de nuestro estudio, el contacto entre la aguja y un nervio durante el bloqueo femoral sucede a menudo con el enfoque fuera de plano. Un abordaje en plano tiene como resultado un bloqueo femoral igualmente efectivo, y una incidencia menor del contacto entre la aguja y un nervio

Incidence of intraneural needle insertion in ultrasound-guided femoral nerve block: a comparison between the out-of-plane versus the in-plane approaches.

BACKGROUND: The optimal method of ultrasound-guided femoral nerve block (in-plane vs. out-of-plane) has not been established. We tested the hypothesis that the incidence of needle-nerve contact may be higher with out-of-plane than with in-plane needle insertion. METHODS: Forty-four patients with hip fracture (American Society of Anaesthesiologists physical status I-III) were randomized to receive the femoral block with an out-of-plane approach (needle inserted at a 45-60° angle 1cm caudal to the midpoint of the ultrasound probe just above the femoral nerve) or with an in-plane technique (needle inserted 0.2-0.4 cm from the side of the probe lateral to the femoral nerve). Data collected included depth of needle insertion, response to nerve electric stimulation, and distribution of the injected volume in relation to the nerve (anterior vs. posterior, the latter assuming needle-nerve contact). The sensory block onset was tested at 20 min and block recovery and any neurologic symptoms were evaluated at 24h. RESULTS: The incidence of needle-nerve contact was significantly higher with the out-of-plane approach (14/22 patients [64%]) than with the in-plane approach (2/22 patients [9%]) (p<0.001) (OR=17.5, 95% CI: 4-79). The rate of paraesthesia on crossing the fascia iliaca was similar in the two groups. All blocks uneventfully regressed; and no patient developed neurologic symptoms. CONCLUSIONS: Under the conditions of our study, needle-nerve contact during femoral nerve block occurs frequently with the out-of-plane approach. An in-plane approach results in an equally effective femoral block and less incidence of needle-nerve contact.