Ultrasound evaluation reduces the incidence of Difficult Spinal Anesthesia: prospective observational study

Although Spinal Anesthesia (SA) it is considered a safe procedure, it may give complications including headache and spinal hematoma, whose incidence increases during multiple attempts. This prospective observational study aimed to analyze the impact of pre-procedural Ultrasound (US) in reducing the incidence of difficult SA, defined as the need for a second skin puncture.

Data collection included incidence of failed and difficult SA and if US evaluation (Fig. 1) was performed before SA . Moreover, we calculated the neuraxial block assessment (NBA) score to predict a high probability of difficult SA, defined as the presence of almost two risk factors (N score) including: absence of spinous processes visibility/palpability, column deformities, history of difficult SA.

824 patients were included. Among them, 382 underwent preprocedural US evaluation and 442 did not. US assisted SA was associated with a significant lower risk of failure (1.6% vs. 8.1%) and difficult procedure (13% vs. 87%); p < 0.001 (Fig.2). A subgroup analysis was performed on 400 patients with difficult SA predictors. In this case, the difference in failed SA between US assisted and blind procedures was even greater (1.6 % vs. 16.2%, respectively); p < 0.001. A similar trend was observed for the incidence of difficult SA (15% vs. 41.8); p < 0.001. (Fig. 3)

Ultrasound evaluation can significantly reduce the incidence of failed and difficult spinal anesthesia, especially in those patients with predicted difficult SA. This may lead to save time, increase patient comfort and reduce the risk of complications.