Ultrasound-Guided Anterior Approach to a Sciatic Nerve Block: Influence of Lower Limb Positioning on the Visibility and Depth of the Sciatic Nerve

Advancing pain management for extremity trauma: the evolution of ultrasound-guided nerve blocks for patients in the supine position in trauma centers

PURPOSE

Trauma, particularly extremity trauma, poses a considerable challenge in healthcare, especially among young adults. Given the severity of patient pain and the risks associated with excessive opioid use, managing acute pain in trauma centers is inherently complex. This study aims to investigate the application and benefits of ultrasound-guided nerve blocks for early pain management in patients with extremity trauma positioned supine.

METHODS

A comprehensive literature review was conducted to assess the effectiveness and advantages of ultrasound-guided peripheral nerve blocks in the acute pain management of extremity trauma patients in the supine position. Special emphasis was placed on evaluating the selection criteria, indications, contraindications, adverse reactions, and potential complications associated with these nerve block techniques.

RESULTS

Ultrasound-guided nerve blocks represent a safer and more precise option for managing pain in extremity trauma patients placed in the supine position. These techniques offer significant advantages in terms of reducing healthcare expenses, diminishing reliance on opioid medications, and mitigating opioid-related complications. Nonetheless, challenges may arise due to the necessity for patient cooperation during specific nerve block procedures.

CONCLUSION

Ultrasound-guided nerve blocks present a promising avenue for early pain management in extremity trauma patients positioned supinely. Their implementation can lead to improved patient outcomes by alleviating pain severity, reducing opioid consumption, and cutting down healthcare costs. Further research and clinical integration of these techniques is imperative to enhance pain management protocols in trauma centers.

The influence of patient position on ultrasound examination of the sciatic nerve in the popliteal fossa: A cross-sectional study

Introduction/Purpose

Ultrasound-guided popliteal fossa sciatic nerve (PFSN) blocks are performed with patients in the supine, lateral or prone position. No known studies compare the quality of images obtained from each approach. This study examines the quality of supine and prone PFSN ultrasound images.

Methods

Thirty-eight adult volunteers were sorted into two groups. Five regional anaesthesiologists performed ultrasound examinations of the PFSN on volunteers in supine and prone positions. Popliteal fossa sciatic nerve image quality was analysed with grayscale techniques and peer evaluation. Popliteal fossa sciatic nerve depth, distance from the popliteal crease and time until optimal imaging were recorded.

Results

The grayscale ratio of the PFSN vs. the background was 1.83 (supine) and 1.75 (prone) (P = 0.034). Similarly, the grayscale ratio of the PFSN vs. the immediately adjacent area was 1.65 (supine) and 1.55 (prone) (P = 0.004). Mean depth of the PFSN was 1.6 cm (supine) and 1.7 cm (prone) (P = 0.009). Average distance from the popliteal crease to the PFSN was 5.9 cm (supine) and 6.6 cm (prone) (P = 0.02). Mean time to acquire optimal imaging was 36 s (supine) and 47 s (prone) (P = 0.002). Observers preferred supine positioning 53.8%, prone positioning 22.5% and no preference 23.7% of the time. Observers with strong preferences preferred supine imaging in 70.9% of cases.

Conclusions

Supine ultrasound examination offered quicker identification of the PFSN, in a more superficial location, closer to the popliteal crease and with enhanced contrast to surrounding tissue, correlating with observer preferences for supine positioning. These results may influence ultrasound-guided PFSN block success rates, especially in difficult-to-image patients.

Evaluation of a New Method of Sciatic Nerve Block: A Prospective Pilot Study

Purpose

The location of the sciatic nerve deep within the thigh tissue makes it challenging to locate while the patient is in a supine position. The posterior intermuscular septum of the thigh, which encircles the posterior surface of the adductor magnus muscle (AMM), is where the sciatic nerve is located. Our hypothesis was that administering local anesthetic injections into this area could block the sciatic nerve. Therefore, our aim was to evaluate the effectiveness of sciatic nerve block achieved by injecting local anesthetic into the posterior intermuscular septum of the thigh, named the AMM approach.

Methods

Twenty-six patients undergoing total knee arthroplasty were included in the study. We performed an ultrasound-guided sciatic nerve block by injecting 20 mL of 0.25% ropivacaine into the posterior surface of the adductor magnus muscle, using the AMM approach. Additionally, we administered a femoral nerve block with 20 mL of 0.4% ropivacaine. We assessed the sensory and motor effects of the blockade in the operated lower limb and recorded postoperative pain scores at 0, 4, 8, 12, 24, and 48 hours after the operation.

Results

The AMM approach successfully block the sciatic nerve in all 26 patients. The onset of the sensory and motor blockades was achieved within 5.4 ± 1.9 min and 8.7 ± 3.5 min, respectively. We achieved a satisfactory position with the first puncture in 19 of 26 patients (73.1%). The muscle strength of the tibialis anterior immediately after surgery was 4 (ranging from 2 to 5). Additional rescue analgesics were required in 5 of the 26 patients (19.2%) during the first 24 hours postoperatively.

Conclusion

The AMM approach is an innovative and effective method for sciatic nerve block. When combined with simultaneous femoral nerve block in patients undergoing total knee arthroplasty, it provides a useful analgesic treatment option.

Identification of the popliteal sciatic nerve through the above-knee lateral approach provides superior echogenicity and ultrasound visibility: a patient volunteer trial

BACKGROUND

Distinguishing light-echoed nerves from surrounding structures is challenging but may be important in nerve block administration. We evaluated the effect of patient characteristics on the echogenicity or visibility of the popliteal sciatic nerve (PSN).

METHODS

This study included adult patients who presented to the operating room as volunteers. The primary outcome was the success rate of nerve identification by ultrasound using different PSN access paths. The secondary outcome included the PSN visibility score (VIS), scan time, and PSN depth. Logistic regression analysis was used to identify factors associated with the PSN identification success rate. The body mass index (BMI) proximal-based cut-off was used to compare the PSN identification success rate through different access paths.

RESULTS

The PSN was successfully identified in 89.7% of the volunteers. The access paths (P < 0.01) and BMI (P = 0.01) were identified as independent predictors of successful PSN identification. A higher PSN identification success rate (P = 0.01), a higher VIS (P < 0.01), a more superficial PSN depth (P < 0.01), and a shorter scan time (P < 0.01) were observed in the above-knee lateral approach. Among volunteers with BMI ≥ 26.77 kg/m2, the PSN identification success rate through the above-knee lateral approach was significantly higher (P < 0.01), and PSN depth was shallower (P < 0.01) than through the medial approach.

CONCLUSIONS

The ultrasound-guided above-knee lateral approach for PSN block improved the PSN identification success rate, ensured a more superficial nerve location, and provided a clearer image.