COMPARISON OF PATIENT POSITION AND MIDLINE LUMBAR NEURAXIAL ACCESS VIA STATISTICAL MODEL REGISTRATION TO ULTRASOUND

Patient positioning and needle puncture site are important for lumbar neuraxial anesthesia. We sought to identify optimal patient positioning and puncture sites with a novel ultrasound registration. We registered a statistical model to volumetric ultrasound data acquired from volunteers (n = 10) in three positions: (i) prone; (ii) seated with thoracic and lumbar flexion; and (iii) seated as in position ii, with a 10 degrees dorsal tilt. We determined injection target size and penetration success by simulating lumbar injections on validated registered models. Injection window and target area sizes in seated positions were significantly larger than those in prone positions by 65% in L23 and 130% in L34; a 10 degrees tilt had no significant effect on target sizes between seated positions. In agreement with computed tomography studies, simulated L23 and L34 injections had the highest success at the 50% and 75% midline puncture sites, respectively, measured from superior to inferior spinous process. We conclude that our registration to ultrasound technique is a potential tool for tolerable determination of puncture site success in vivo. (C) 2018 World Federation for Ultrasound in Medicine & Biology. All rights reserved.