Comparison of Analgesic Outcomes Following Sciatic Nerve Blockade Performed by Resident Trainees and Nurse Anesthetists

Background and objectives: Peripheral nerve blockade requires regional anesthesia skills that are taught in several formats and assessing technical proficiency has shifted from fulfillment of quotas to comprehensive procedural evaluation. Complete analgesia is the clinical endpoint validating successful nerve blockade but patient, technical and procedural factors influence this result. The purpose of this study was to determine if physician trainee or nurse anesthetist administered sciatic nerve blockade influence postoperative pain scores and opioid analgesic requirements and if patient factors, technique and repetition influence this outcome. Method: Sciatic nerve blockade by nerve stimulation and ultrasound based techniques were performed by senior anesthesiology resident trainees and nurse anesthetists under the supervision of regional anesthesia faculty. Preoperative patient characteristics including obesity, trauma, chronic pain, opioid use and preoperative pain scores were recorded and compared to the post-procedure pain scores and opioid analgesic requirements upon discharge from the post-anesthesia care unit and 24 hours following sciatic nerve blockade. Results: 93 patients received sciatic nerve blockade from 22 nurse anesthetists and 21 residents during 36 months. A significant relation between training background and improved pain scores was not demonstrated but transition from nerve stimulation to ultrasound guided techniques lowered immediate opioid usage in all groups. Patients with pre-existing chronic opioid use had higher postoperative pain scores and opioid dosages following nerve block. Conclusion: Patient analgesia should be an integral measure of proficiency in regional anesthesia techniques and evaluating this procedure outcome for all practitioners throughout their training and beyond graduation will longitudinally assess technical expertise.

Ultrasound Mapping of Stimulated Finger Flexion During Infra-Clavicular Brachial Plexus Nerve Blockade for Elbow Arthroplasty and Its Correlation To Postoperative Analgesia

Background: Infraclavicular brachial plexus nerve blockade (ICNB) is a very common anesthetic procedure performed for upper extremity surgery at the elbow and distally, however the rate of adequate analgesia is variable among patients. Ultrasound guidance (US) has not been demonstrated to increase the success rate of ICNB when compared to nerve stimulator (NS) guidance. Combined US and NS guided ICNB have not been reported, although there is a call for more trials comparing the two techniques. This study was performed to observe if a specific anatomic region near the axillary artery of the brachial plexus identified by finger flexion with nerve stimulation results in improved postoperative analgesia. Method: Patients undergoing elective elbow arthroplasty received a postoperative ICNB. The angle of the nerve stimulator needle tip and the radial distance from the center of the arterial lumen at which an optimal finger flexion twitch response was observed were measured with ultrasound imaging. Pain scores and postoperative opioid dosages on discharge from the post anesthesia care unit and at 24 hours after surgery were recorded. Results: 11 patients enrolled in this study. Adequate finger flexion response to nerve stimulation that resulted in complete analgesia was more frequently observed when the needle was located in the postero-superior quadrant in relation to the axillary artery. Identifying a specific point near the brachial plexus in relation to the artery that consistently provides superior analgesia is desirable and would lead to improved analgesia and faster onset time of nerve blockade and would reduce the need for other approaches for brachial plexus blockade with their associated disadvantages.

Ultrasound Mapping of Nerve Stimulator Response during Sciatic Nerve Blockade and Relation to Postoperative Pain Scores

1.1 Background and Purpose: Ultrasound guided sciatic nerve blockade has rapid onset but at 24 hours pain is greater than nerve stimulator techniques. Injection of the nerve branches or trunk and sub-sheath blockade increase success and reduce onset times but risk injury. This study mapped needle coordinates for sciatic nerve blockade with nerve stimulation and its relation to postoperative pain scores. 1.2 Method: Angle and distance of the needle tip and infusion catheter from the popliteal sciatic nerve at which stimulated plantar flexion occurred were measured. Pain scores at postanesthesia unit discharge and 24 hours were recorded. 1.3 Results: 81% of opioid naïve patients reported immediate analgesia and 20.8% at 24 hours. In opioid tolerant patients 56.8% reported immediate analgesia and 9.1% at 24 hours. Plantar flexion was observed with the needle in the posterior medial quadrant near the sciatic nerve. Opioid tolerant patients reported adequate analgesia when the needle was located more medially and proximally to the sciatic nerve. 1.4 Conclusion: Stimulated plantar flexion is isolated to a narrow angular range in the posterior medial quadrant adjacent to the sciatic nerve. Opioid tolerant patients report adequate analgesia if the needle and catheter are more medial and proximal to the nerve surface.

Patient Variability in Sciatic Nerve Branch Point Distance Using Ultrasound Guided Localization

Background and Objectives: Improved ultrasound and needle technology make popliteal sciatic nerve blockade a popular anesthetic technique and imaging to localize the branch point of the common peroneal and posterior tibial components is important because successful blockade techniques vary with respect to injection of the common trunk proximally or separate injections distally. Nerve stimulation, ultrasound, cadaveric and magnetic resonance studies demonstrate variability in distance and discordance between imaging and anatomic examination of the branch point. The popliteal crease and imprecise, inaccessible landmarks render measurement of the branch point variable and inaccurate. The purpose of this study was to use the tibial tuberosity, a fixed bony reference, to measure the distance of the branch point. Method: During popliteal sciatic nerve blockade in the supine position the branch point was identified by ultrasound and the block needle was inserted. The vertical distance from the tibial tuberosity prominence and needle insertion point was measured. Results: In 92 patients the branch point is a mean distance of 12.91 cm proximal to the tibial tuberosity and more proximal in male (13.74 cm) than female patients (12.08 cm). Body height is related to the branch point distance and is more proximal in taller patients. Separation into two nerve branches during local anesthetic injection supports notions of more proximal neural anatomic division. Limitations: Imaging of the sciatic nerve division may not equal its true anatomic separation. Conclusion: Refinements in identification and resolution of the anatomic division of the nerve branch point will determine if more accurate localization is of any clinical significance for successful nerve blockade.

Post-Operative Pain Scores and Level of Regional Anesthesia Expertise: Using Clinical Outcomes to Assess Procedural Proficiency

Background and Objectives: Peripheral nerve blockade requires regional anesthesia skills that trainees learn in several formats. Technical proficiency has shifted from a quota to comprehensive procedural evaluation. Successful nerve blockade is the clinical endpoint validating proficiency but patient, technical and procedural factors influence this result. The purpose of this study was to determine if procedural expertise for sciatic nerve blockade influenced postoperative pain scores and opioid requirements and if patient factors, technique and repetition influenced this outcome. Method: Sciatic nerve blockade by nerve stimulation and ultrasound guidance and training level of the resident performing the procedure were recorded. Patient obesity, trauma, chronic pain, opioid use and preoperative pain scores were compared to post-procedure pain scores and opioid analgesic requirements. Results: 102 patients received sciatic nerve blockade from 47 trainees over a 36 month interval. A significant relation between training level and improved pain scores was not demonstrated but transition from nerve stimulation to ultrasound guidance lowered scores in all groups. Nerve blockade failure was frequent with chronic opioid use and trauma. Conclusion: Analgesic outcomes should be an integral part of assessment of proficiency in regional anesthesia techniques. Evaluating outcomes of procedures throughout training will longitudinally assess technical expertise.