Background and objective: Lumbar epidural anaesthesia usually affects both legs. The aim was to compare the success rates of ultrasound-aided vs. classical midline epidural catheter insertion for ipsilateral-dominant blocks and analgesia in patients undergoing total hip arthroplasty.
Methods: The protocol was designed as a prospective randomised single-blind study. In the ultrasound group (n = 12), ultrasound examination was performed to determine the puncture point and direction for ipsilateral-dominant block. In the midline group (n = 12), epidural puncture was performed by the usual midline approach. Rates of successful ipsilateral-dominant block using 6 ml of lidocaine 1.5% wt vol⁻¹ (primary outcome) and effects of patient-controlled epidural analgesia using ropivacaine 0.2% wt vol⁻¹ (secondary outcomes) were evaluated.
Results: The rates of successful ipsilateral-dominant block were 83% in the ultrasound group and 17% in the midline group (P = 0.004). Sensory and motor functions on the non-operated side in the ultrasound group were significantly better maintained than those on the operated side and compared with those on the non-operated side in the midline group (P < 0.05). Pain scores at mobilisation, incidence of post-operative nausea and vomiting and frequency of use of supplemental analgesics were significantly lower in the ultrasound group than in the midline group (P < 0.05).
Conclusion: The use of ultrasound significantly improves the success rate of ipsilateral epidural block compared with the standard midline approach.