Aim of this study was to compare anatomical landmark technique and pre-procedural lumbar spine ultrasonography (US) in choosing the L4-L5 interspace, precision in determining midline and measuring subarachnoid depth (SAD) and actual needle depth (ND) when performing spinal anaesthesia. In this prospective observational study we included 31 patients with planned lower limb orthopaedic surgery with spinal anaesthesia. Before lumbar puncture L4-5 interspace and midline were marked using landmark technique, then the lumbar US was performed. Deviation from planned interspace was analysed using paramedian sagittal plane and shift from midline was determined using median transverse plane (TP). Then the SAD was measured using best echogenic window in TP. After performing spinal anaesthesia actual ND was measured. The agreement between measurements were analysed using Bland-Altman test. US visualisation quality of posterior complex was recorded. Median patient age was 61 (53-64) years, 11 (35%) male and 20 (65%) female patients were enrolled in this study. Median BMI was 27,5 (24,7-30,6). Deviation from L4-5 interspace occurred in 26% (8/31) cases of which 19% (6/31) were L3-4 and 6% (2/31) L5-S1 interspace. Mean (SD) deviation from midline was 1,3 (1,5) mm. The mean US measured SAD in TP and actual ND was 5,1 (0,8) cm and 6,2(0,9) cm respectively (p<0.001). In 29% US visualisation of posterior complex was good, in 65 % - sufficient, but in 6% of cases visualisation of posterior complex was impossible. Anatomical landmark technique was imprecise in identifying L4-5 interspace in 26% of cases, but deviation from midline was minimal. However, measured SAD was significantly smaller than actual ND. We would recommend usage of pre-procedural lumbar spine ultrasound to assess the midline and planned interspace to increase precision before performing lumbar puncture in spinal anesthesia.
- 3.4. Other publications in conference proceedings (including local)