Rivanna Ultrasound for Neuraxial Block

Administration of (neuraxial blocks) spinal and epidural blocks is commonly achieved by first palpating the landmarks for midline with spinous process and iliac crest for L3-4-5 intervertebral spaces. With an epidural block, a loss of resistance in a pressurized syringe is used to incrementally advance the epidural needle until identification of epidural space with loss of resistance in the pressurized syringe. With a spinal block, the spinal needle is advanced incrementally until a noted "feel" of dural puncture together with return of spinal fluid via the spinal needle. The palpation technique and somewhat "blind" technique to identify the spinal and epidural spaces become more difficult and less reliable particularly with the increasing prevalence of the morbid and super-morbid obese patients. Ultrasound devices have become common and successful with non-neuraxial blocks and venous accesses, both involving mostly non-bony, soft tissues. Application of conventional ultrasound for neuraxial blocks has been limited by its bulkiness, limited imaging for bony structures and lack of automated artificial intelligent algorithm for pattern recognition. Recent technological advancement has addressed the aforementioned limitations. Rivanna Accuro is one such device that has gained FDA approval and may have helped in addressing some of these issues. It is a handheld (pocket size) U/S device with real time pattern recognition for bony structures such as the spine while providing 3-D overlay for recognition of the midline spinous process and epidural spaces and distance. The investigators hypothesize that the Rivanna Accuro or similar U/S device would reduce time to success of identifying epidural and/or intrathecal spaces as compared to conventional palpation method. We will compare placement of neuraxial block between palpation method versus ultrasound method. We will compare placement of spinal block for cesarean delivery with palpation versus with ultrasound method, and then comparing placement of neuraxial analgeisa block (combined spinal epidural analgesia) for labor analgesia with palpation versus ultrasound method.