Ultrasound for Neuraxial Anesthesia

Neuraxial anesthesia will be performed to the patients after detection of the puncture site by ultrasound scan of the spine. The scanning will be performed as described by Arzola et al. The L3-L4 space will be identified by palpation and identification of the landmarks (Tuffier's line). The ultrasound probe will be placed perpendicular to the long axis of the spine. The spinous process will be identified (bright signal followed by dark triangular area). The probe will be moved to cephalad or caudal to identify the intervertebral space and when the best view of the ligamentum flavum is achieved two marks will be drawn on the skin: one at the center of the upper surface of the probe and one at the center of the right lateral vertical side of the probe. The intersection of the two landmarks will be the puncture site. The distance from the skin to the ligamentum flavum will be measured by the ultrasound caliper.

Neuraxial anesthesia will be performed to the patients after detection of the puncture site by the identification of the landmarks. The L3-L4 space will be identified by palpation of the posterior iliac crests and the ideal intervertebral space will be selected after palpation of the spinous processes.