Ultrasound and local anaesthesia. Part III: ultrasound and neuroaxial local anaesthesia

The use of ultrasound as a diagnostic tool for the visualisation of the epidural space has effects on the quality and the performance of epidural anesthesia. This work presents an overview of the recent experiences with ultrasound for epidural anesthesia and on the possibilities for ultrasound imaging techniques. The results of visualisation of the epidural space and its limiting structures obtained by various working groups are presented. We review all presently available data on the prediction of the puncture depth. The various working groups found correlations between predicted and effective puncture depth between 0.79 and 0.98 and the precision of the measurement was 57-7.7 mm. Regarding the prediction of the puncture angle there was a poor correlation ranging between 0.07 and 0.31. The precision between the measured and the punctured angles was found to be 10-13.4degrees. In all available prospective randomised studies on the puncture effects in the lumbar epidural space,the influence of ultrasound showed a significant reduction (p<0.03) of the puncture attempts, and we found a significant (p<0.05) reduction in the number of puncture levels. The ultrasound-guided puncture allowed an ideal needle trajectory and a more precise application of the catheter. A significant improvement of analgesia quality (p<0.035) and patient satisfaction (p<0.006) could be achieved. The metaanalysis of the different studies regarding puncture quality by ultrasound-guided peridural anaesthesia showed a clear advantage for the use of imaging techniques.