The practice of central neuraxial block (CNB) has traditionally relied on the palpation of bony anatomical landmarks, namely the iliac crests and spinous processes, together with tactile feedback during needle insertion.
However, these landmarks may be difficult to identify accurately—a problem exacerbated by altered patient anatomy, including obesity, age-related changes, and previous spinal surgery.
Nonetheless, detailed knowledge of lumbar spinal anatomy and sonoanatomy is essential for interpretation of neuraxial ultrasound images.
In brief, Ultrasound-assisted CNB also know as Ultrasound-guided lumbar central neuraxial block is an advanced technique for use in patients with difficult spinal anatomy.
That is why, performing a pre-procedural scan helps to identify relevant landmarks and thus guide subsequent needle insertion.
Compared to palpation of surface anatomical landmarks, pre-puncture ultrasound scan can identify the vertebral levels more accurately.
The use for CNB allows for any anatomical variances to be seen and their possible complicating effects adjusted for.
In addition it has had a significant reduction in both skin punctures and needle redirection attempts with the use of ultrasound.
The use of the portable ultrasound as pre-procedural scan also improves the technical efficiency of CNB by facilitating precise identification of underlying anatomical structures.