Ultrasound for central neuraxial blocks

Recent advances in ultrasound (US) imaging have significantly improved our understanding of spinal sonoanatomy. Today, US imaging has been used to assist or guide central neuraxial blocks, and it appears to be a promising alternative to traditional landmark-based technique. US is noninvasive, safe, simple to use, can be quickly performed, does not involve exposure to radiation, provides real-time images, and is free from adverse effects. Currently, the majority of the outcome data are from its application in the lumbar region. A scout (prepuncture) scan allows the operator to preview the spinal anatomy, identify the midline, accurately predict the depth to the epidural space, and determine the optimal site and trajectory for needle insertion. When used for central neuraxial blocks, it also improves the success rate of epidural access on the first attempt, reduces the number of puncture attempts or the need to puncture multiple levels, and improves patient comfort during the procedure. Preliminary data suggest that US may also offer technical advantages in patients with abnormal spinal anatomy. It is also an excellent teaching tool and improves the learning curve of epidural blocks in parturients. However, the use of US for central neuraxial blocks is still in its infancy, and there is a need for more research in this state of the art regional anesthesia before it can become a standard of care.