A randomised controlled trial of ultrasound-assisted spinal anaesthesia

Pre-procedural ultrasound scanning has been used to facilitate spinal anaesthesia in patients with difficult anatomical landmarks and shown to improve first-attempt success rates in some studies. We studied whether pre-procedural ultrasound scanning improved first-attempt success rate and decreased time taken for the procedure in the general adult population. In this prospective, randomised controlled trial, 170 American Society of Anesthesiologists 1 to 3 patients aged between 21 and 80 years were recruited. Informed consent was obtained. Patients were randomised into two groups, ultrasound-guided identification of landmarks (Ultrasound Group) and manual palpation of landmarks (Manual Palpation Group). The primary outcome was first-attempt success rate and secondary outcomes were time taken to perform procedure, number of needle redirections, patient satisfaction and complications. The first-attempt success rate was 64% in the Ultrasound Group and 52% in the Manual Palpation Group (P=0.16). Time taken for procedure was shorter in the Ultrasound Group compared to the Manual Palpation Group (2.9±3.6 minutes versus 3.9±3.7 min, P= 0.007). Patient satisfaction was higher in the Ultrasound Group. There were no differences in complications. As there was no statistically significant difference in first-attempt success rates between the two groups, existing evidence for routine pre-procedural scanning for all patients is inadequate. The current use of pre-procedural ultrasound scanning will probably be limited to selected patients where spinal anaesthesia may be technically challenging with conventional methods.