Ultrasound-guided Sacral Plexus Nerve Block bests classical technique inpatients undergoing orthopedic below-knee limb surgeries: Study

Historically, regional anesthesia for lower limb orthopedic surgeries has primarily involved spinal or epidural anesthesia. Recent study aimed to compare the block performance characteristics after ultrasound-guided sacral plexus nerve block (SNB) using the parasacral parallel shift (PSPS) approach versus the classical approach in patients undergoing orthopedic below-knee limb surgeries. A total of 144 adult patients were randomized to receive either the classical approach (Group C) or the PSPS approach (Group P). The primary outcome measured was the scanning time between the two groups, and the secondary outcomes included needling time, sensory and motor block onset, and postoperative analgesic characteristics.

Results and Comparative Analysis

Results of the study showed that the needling and scanning times were significantly lesser in the PSPS approach group compared to the classical approach group. The PSPS approach also resulted in higher rates of complete sensory and motor nerve blockade of the sciatic nerve. Additionally, the PSPS approach demonstrated lower block performance time, time for sensory block, and time for motor block compared to the classical approach, with comparable postoperative analgesic characteristics between the two groups. The study indicated that the sacral plexus block with ultrasound-guided PSPS technique had a lower block performance time with lesser needling and scanning time than the classical approach.

Technical Challenges and Ethical Considerations

The study findings also highlighted technical challenges in visualizing nerves/plexus that depend on different approaches and patient-related factors. Technical differences between the classical and PSPS approaches for sacral plexus block, including the visualization of the iliac bone contour and the sciatic nerve, were described. The study protocol was approved by the institute’s ethics committee, and the trial was conducted in accordance with the principles of the Declaration of Helsinki. The study reported no significant complications related to the performance of the block in either group. Additionally, the limitations of the study were acknowledged, including the lack of inclusion of patients requiring proximal thigh/hip/knee surgeries and the average BMI of the patients being less than 30 kg/m2, which limits the generalizability of the results to certain subsets of patients.

Overall, the study demonstrated that the ultrasound-guided sacral plexus block using the PSPS approach had a higher success rate, shorter block performance time, and earlier sensory and motor block onset compared to the classical technique. The study provided valuable insights into the efficacy of different approaches for sacral plexus nerve blocks and their implications for patients undergoing orthopedic below-knee limb surgeries.

Key Points

1. The study compared the performance characteristics of ultrasound-guided sacral plexus nerve block (SNB) using the parasacral parallel shift (PSPS) approach versus the classical approach in patients undergoing orthopedic below-knee limb surgeries.

2. A total of 144 adult patients were randomized to receive either the classical approach (Group C) or the PSPS approach (Group P). The primary outcome measured was the scanning time between the two groups, and the secondary outcomes included needling time, sensory and motor block onset, and postoperative analgesic characteristics.

3. The study found that the needling and scanning times were significantly lower in the PSPS approach group compared to the classical approach group. The PSPS approach also resulted in higher rates of complete sensory and motor nerve blockade of the sciatic nerve. Additionally, the PSPS approach demonstrated lower block performance time, time for sensory block, and time for motor block compared to the classical approach, with comparable postoperative analgesic characteristics between the two groups.

4. The study highlighted technical challenges in visualizing nerves/plexus that depend on different approaches and patient-related factors. Technical differences between the classical and PSPS approaches for sacral plexus block, including the visualization of the iliac bone contour and the sciatic nerve, were described.

5. The study was conducted in accordance with the principles of the Declaration of Helsinki and reported no significant complications related to the performance of the block in either group. However, the study acknowledged limitations, including the lack of inclusion of patients requiring proximal thigh/hip/knee surgeries and the average BMI of the patients being less than 30 kg/m2, which limits the generalizability of the results to certain subsets of patients.

6. Overall, the study demonstrated that the ultrasound-guided sacral plexus block using the PSPS approach had a higher success rate, shorter block performance time, and earlier sensory and motor block onset compared to the classical technique, providing valuable insights into the efficacy of different approaches for sacral plexus nerve blocks in patients undergoing orthopedic below-knee limb surgeries.

Reference –

Nair R, Samra T, Ashok V, Jain K. Efficacy of ultrasound‑guided classical versus parasacral parallel shift technique of sacral plexus block for lower limb surgeries – A randomized controlled trial. Indian J Anaesth 2024;68:712‑7.