The median effective dose of ropivacaine for ultrasound-guided peripheral nerve block around the hip capsule in elderly patients with intertrochanteric fractures.

BACKGROUND: This study aimed to establish the median effective dose (ED50) and 95% confidence interval (CI) of 0.25% ropivacaine for ultrasound-guided pericapsular nerve group (PENG) block for facilitating spinal anesthesia positioning in elderly patients with intertrochanteric femoral fractures. METHODS: The elderly patients received elective proximal femoral nail antirotation (PFNA) surgery under spinal anesthesia. By adjusting the needle bevel orientation toward the superior pubic ramus, an ultrasound-guided PENG block was administered five minutes before positioning. The dose of 0.25% ropivacaine was titrated according to the highest pain level reported on the visual analog scale (VAS) during positioning, starting from 10 ml with subsequent adjustments in 1 ml increments. The modified Dixon Up-and-Down sequential method was used to determine the effective dose, and the median ED50 along with its 95% CI for 0.25% ropivacaine were calculated using Probit analysis. VAS scores were recorded at baseline, 5 min after block administration, and during positioning. Postoperative sufentanil consumption and block-related complications—including bleeding, hematoma, quadriceps weakness, and local anesthetic toxicity—were also documented. RESULTS: A total of thirty elderly patients with intertrochanteric femoral fractures were enrolled. The ED50 of 0.25% ropivacaine for a PENG block to facilitate spinal anesthesia positioning was determined to be 3.674 ml (95% CI: 1.879–4.842 ml). At five minutes post-block, both the VAS score during passive movement and the highest VAS score recorded during positioning were significantly reduced compared to pre-block values. However, no significant differences were observed in postoperative VAS scores, postoperative sufentanil consumption, or the incidence of complications. CONCLUSION: For elderly intertrochanteric fracture patients, ED50 of 0.25% ropivacaine PENG block was 3.674 ml. By adjusting the needle bevel orientation, a low-dose local anaesthetic can effectively relieve pain without affecting quadriceps strength.