Primary failure of thoracic epidural analgesia: revisited.

Primary failure of thoracic epidural analgesia (TEA) remains an important clinical problem, whose incidence can exceed 20% in teaching centers. Since loss-of-resistance (LOR) constitutes the most popular method to identify the thoracic epidural space, the etiology of primary TEA failure can often be attributed to LOR's low specificity. Interspinous ligamentous cysts, non-fused ligamenta flava, paravertebral muscles, intermuscular planes, and thoracic paravertebral spaces can all result in non-epidural LORs. Fluoroscopy, epidural waveform analysis, electrical stimulation, and ultrasonography have been proposed as confirmatory modalities for LOR.The current evidence derived from randomized trials suggests that fluoroscopy, epidural waveform analysis, and possibly electrical stimulation, could decrease the primary TEA failure to 2%. In contrast, preprocedural ultrasound scanning provides no incremental benefit when compared with conventional LOR. In the hands of experienced operators, real-time ultrasound guidance of the epidural needle has been demonstrated to provide comparable efficacy and efficiency to fluoroscopy.Further research is required to determine the most cost-effective confirmatory modality as well as the best adjuncts for novice operators and for patients with challenging anatomy. Moreover, future trials should elucidate if fluoroscopy and electrical stimulation could potentially decrease the secondary failure rate of TEA, and if a combination of confirmatory modalities could outperform individual ones.

Patient-Reported Quality of Recovery after Local Anesthesia versus Brachial Plexus Block in Hand Surgery: A Randomized Controlled Study.

BACKGROUND: Both local anesthesia (LA) and brachial plexus (BP) anesthesia are commonly used in hand surgery. LA has increased efficiency and reduced costs, but BP is often favored for more complex hand surgery, despite requiring greater time and resources. The primary objective of this study was to assess the quality of recovery of patients who received LA or BP block for hand surgery. Secondary objectives were to compare postoperative pain and opioid use. METHODS: This randomized, controlled, noninferiority study enrolled patients undergoing surgery distal to the carpal bones. Patients were randomized to either LA (wrist or digital block) or BP block (infraclavicular block) before surgery. Patients completed the Quality of Recovery-15 questionnaire on postoperative day (POD) 1. Pain level was assessed with a numeric pain rating scale, and narcotic consumption was recorded on POD1 and POD3. RESULTS: A total of 76 patients completed the study (LA, n = 46, BP, n = 30). No statistically significant difference was found for median Quality of Recovery-15 score between LA [127.5 (interquartile range, 28)] and BP block [123.5 (interquartile range, 31)]. The inferiority margin of LA to BP block at the 95% confidence interval was less than the minimal clinically important difference of 8, demonstrating noninferiority of LA compared with BP block. There was no statistically significant difference between LA and BP block for numeric pain rating scale scores or narcotic consumption on POD1 and POD3 ( P > 0.05). CONCLUSION: LA is noninferior to BP block for hand surgery with regard to patient-reported quality of recovery, postoperative pain, and narcotic use. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Cadaveric study investigating the femoral nerve-sparing volume for pericapsular nerve group (PENG) block.

BACKGROUND: This cadaveric study investigated the maximum effective volume of dye in 90% of cases (MEV90) required to stain the iliac bone between the anterior inferior iliac spine (AIIS) and the iliopubic eminence (IPE) while sparing the femoral nerve during the performance of pericapsular nerve group (PENG) block. METHODS: In cadaveric hemipelvis specimens, the ultrasound transducer was placed in a transverse orientation, medial and caudal to the anterior superior iliac spine in order to identify the AIIS, the IPE and the psoas tendon. Using an in-plane technique and a lateral-to-medial direction, the block needle was advanced until its tip contacted the iliac bone. The dye (0.1% methylene blue) was injected between the periosteum and psoas tendon. Successful femoral-sparing PENG block was defined as the non-staining of the femoral nerve on dissection. Volume assignment was carried out using a biased coin design, whereby the volume of dye administered to each cadaveric specimen depended on the response of the previous one. In case of failure (ie, stained femoral nerve), the next one received a lower volume (defined as the previous volume with a decrement of 2 mL). If the previous cadaveric specimen had a successful block (ie, non-stained femoral nerve), the next one was randomized to a higher volume (defined as the previous volume with an increment of 2 mL), with a probability of b=1/9, or the same volume, with a probability of 1-b=8/9. RESULTS: A total of 32 cadavers (54 cadaveric hemipelvis specimens) were included in the study. Using isotonic regression and bootstrap CI, the MEV90 for femoral-sparing PENG block was estimated to be 13.2 mL (95% CI: 12.0 to 20.0). The probability of a successful response was estimated to be 0.93 (95% CI: 0.81 to 1.00). CONCLUSION: For PENG block, the MEV90 of methylene blue required to spare the femoral nerve in a cadaveric model is 13.2 mL. Further studies are required to correlate this finding with the MEV90 of local anesthetic in live subjects.

Randomized clinical trial comparing pericapsular nerve group (PENG) block and periarticular local anesthetic infiltration for total hip arthroplasty.

BACKGROUND: This randomized trial compared pericapsular nerve group block and periarticular local anesthetic infiltration in patients undergoing primary total hip arthroplasty. We hypothesized that, compared with pericapsular nerve group block, periarticular local anesthetic infiltration would decrease the postoperative incidence of quadriceps weakness at 3 hours fivefold (ie, from 45% to 9%). METHODS: Sixty patients undergoing primary total hip arthroplasty under spinal anesthesia were randomly allocated to receive a pericapsular nerve group block (n=30) using 20 mL of adrenalized bupivacaine 0.50%, or periarticular local anesthetic infiltration (n=30) using 60 mL of adrenalized bupivacaine 0.25%. Both groups also received 30 mg of ketorolac, either intravenously (pericapsular nerve group block) or periarticularly (periarticular local anesthetic infiltration), as well as 4 mg of intravenous dexamethasone.Postoperatively, a blinded evaluator carried out sensory assessment and motor assessment (knee extension and hip adduction) at 3, 6 and 24 hours. Furthermore, the blinded observer also recorded static and dynamic pain scores at 3, 6, 12, 18, 24, 36 and 48 hours; time to first opioid request; cumulative breakthrough morphine consumption at 24 hours and 48 hours; opioid-related side effects; ability to perform physiotherapy at 6, 24 and 48 hours; as well as length of stay. RESULTS: There were no differences in quadriceps weakness at 3 hours between pericapsular nerve group block and periarticular local anesthetic infiltration (20% vs 33%; p=0.469). Furthermore, no intergroup differences were found in terms of sensory block or motor block at other time intervals; time to first opioid request; cumulative breakthrough morphine consumption; opioid-related side effects; ability to perform physiotherapy; and length of stay. Compared with pericapsular nerve group block, periarticular local anesthetic infiltration resulted in lower static pain scores (at all measurement intervals) and dynamic pain scores (at 3 and 6 hours). CONCLUSION: For primary total hip arthroplasty, pericapsular nerve group block and periarticular local anesthetic infiltration result in comparable rates of quadriceps weakness. However, periarticular local anesthetic infiltration is associated with lower static pain scores (especially during the first 24 hours) and dynamic pain scores (first 6 hours). Further investigation is required to determine the optimal technique and local anesthetic admixture for periarticular local anesthetic infiltration. TRIAL REGISTRATION NUMBER: NCT05087862.

Randomized comparison between pericapsular nerve group (PENG) block and suprainguinal fascia iliaca block for total hip arthroplasty.

BACKGROUND: This randomized trial compared ultrasound-guided pericapsular nerve group block and suprainguinal fascia iliaca block in patients undergoing primary total hip arthroplasty. We selected the postoperative incidence of quadriceps motor block (defined as paresis or paralysis of knee extension) at 6 hours as the primary outcome. We hypothesized that, compared with suprainguinal fascia iliaca block, pericapsular nerve group block would decrease its occurrence from 70% to 20%. METHODS: Forty patients undergoing primary total hip arthroplasty under spinal anesthesia were randomly allocated to receive a pericapsular nerve group block (n=20) using 20 mL of adrenalized levobupivacaine 0.50%, or a suprainguinal fascia iliaca block (n=20) using 40 mL of adrenalized levobupivacaine 0.25%. After the performance of the block, a blinded observer recorded pain scores at 3, 6, 12, 18, 24, 36, and 48 hours; cumulative breakthrough morphine consumption at 24 and 48 hours; opioid-related side effects; ability to perform physiotherapy at 24 and 48 hours; as well as length of stay. Furthermore, the blinded observer also carried out sensory assessment (of the anterior, lateral, and medial aspects of the mid-thigh) and motor assessment (knee extension and hip adduction) at 3, 6, and 24 hours. RESULTS: Compared with suprainguinal fascia iliaca block, pericapsular nerve group block resulted in a lower incidence of quadriceps motor block at 3 hours (45% vs 90%; p<0.001) and 6 hours (25% vs 85%; p<0.001). Furthermore, pericapsular nerve group block also provided better preservation of hip adduction at 3 hours (p=0.023) as well as decreased sensory block of the anterior, lateral, and medial thighs at all measurement intervals (all p≤0.014). No clinically significant intergroup differences were found in terms of postoperative pain scores, cumulative opioid consumption at 24 and 48 hours, ability to perform physiotherapy, opioid-related side effects, and length of hospital stay. CONCLUSION: For primary total hip arthroplasty, pericapsular nerve group block results in better preservation of motor function than suprainguinal fascia iliaca block. Additional investigation is required to elucidate the optimal local anesthetic volume for motor-sparing pericapsular nerve group block and to compare the latter with alternate motor-sparing strategies such as periarticular local anesthetic infiltration. TRIAL REGISTRATION NUMBER: NCT04402450.

Cadaveric study investigating the phrenic-sparing volume for anterior suprascapular nerve block.

BACKGROUND: This cadaveric study investigated the maximum effective volume of dye in 90% of cases (MEV90), required to stain the suprascapular nerve while sparing the phrenic nerve during the performance of an anterior suprascapular nerve block. METHODS: In cadaveric neck specimens, using ultrasound guidance, the block needle was advanced until its tip was positioned underneath the omohyoid muscle next to the suprascapular nerve. The dye was injected in order to achieve circumferential spread around the latter. Successful phrenic-sparing suprascapular nerve block was defined as the non-staining of the phrenic nerve on dissection. Volume assignment was carried out using a Biased Coin Design, whereby the volume of dye administered to each cadaveric specimen depended on the response of the previous one. In case of failure (ie, stained phrenic nerve), the next one received a lower volume (defined as the previous volume with a decrement of 2 mL). If the previous cadaveric specimen had a successful block (ie, non-stained phrenic nerve), the next one was randomized to a higher volume (defined as the previous volume with an increment of 2 mL), with a probability of b=0.11, or the same volume, with a probability of 1 - b=0.89. RESULTS: Thirty-one cadavers (56 cadaveric neck specimens) were included in the study. Using isotonic regression and bootstrap CI, the MEV90 for phrenic-sparing anterior suprascapular nerve block was estimated to be 4.2 mL (95% CI 3.0 to 5.0 mL). The probability of a successful response was estimated to be 0.90 (95% CI 0.84 to 0.96). CONCLUSION: For ultrasound-guided anterior suprascapular nerve block, the MEV90 of dye required to spare the phrenic nerve is 4.2 mL. Further studies are required to correlate this finding with the MEV90 of local anesthetic in live subjects.

Cadaveric investigation of the minimum effective volume for ultrasound-guided suprainguinal fascia iliaca block.

BACKGROUND: This cadaveric dose-finding study investigated the minimum effective volume of dye in 90% of cases (MEV90), required to stain the femoral, lateral femoral cutaneous and obturator nerves for ultrasound-guided suprainguinal fascia iliaca block (SIFIB). METHODS: In cadaveric specimens of the lower limb, the block needle was advanced, medial to the anterosuperior iliac spine, until its tip was positioned between the internal oblique and iliacus muscles underneath the fascia iliaca. The dye was injected inside the fascia iliaca compartment. Volume assignment was carried out using a biased coin design, whereby the volume of dye administered to each cadaveric specimen depended on the response of the previous one. In case of failure, the next one received a higher volume (defined as the previous volume with an increment of 2.5 mL). If the previous cadaveric specimen had a successful block, the next one was randomized to a lower volume (defined as the previous volume with a decrement of 2.5 mL), with a probability of b=0.11, or the same volume, with a probability of 1-b=0.89. Success was defined as the staining of the femoral, lateral femoral cutaneous, and obturator nerves on dissection. RESULTS: Thirty-six cadavers (60 cadaveric specimens) were included in the study. Using isotonic regression and bootstrap CI, the MEV90 for ultrasound-guided SIFIB was estimated to be 62.5 mL (95% CI 60 to 65). CONCLUSION: For ultrasound-guided SIFIB, the MEV90 of dye required to stain the femoral, lateral femoral cutaneous and obturator nerves is 62.5 mL. Further studies are required to correlate this finding with the MEV90 of local anesthetic in human subjects.

Motor-sparing nerve blocks for total knee replacement: A scoping review.

STUDY OBJECTIVE: This scoping review investigates the optimal combination of motor-sparing analgesic interventions for patients undergoing total knee replacement (TKR). DESIGN: Scoping review. INTERVENTION: MEDLINE, EMBASE and CINAHL databases were searched (inception-last week of May 2020). Only trials including motor-sparing interventions were included. Randomized controlled trials lacking prospective registration and blinded assessment were excluded. MAIN RESULTS: The cumulative evidence suggests that femoral triangle blocks outperform placebo and periarticular infiltration. When combined with the latter, femoral triangle blocks are associated with improved pain control, higher patient satisfaction and decreased opioid consumption. Continuous femoral triangle blocks provide superior postoperative analgesia compared with their single-injection counterparts. However, these benefits seem less pronounced when perineural adjuvants are used. Combined femoral triangle-obturator blocks result in improved analgesia and swifter discharge compared with femoral triangle blocks alone. CONCLUSIONS: The optimal analgesic strategy for TKR may include a combination of different analgesic modalities (periarticular infiltration, femoral triangle blocks, obturator nerve block). Future trials are required to investigate the incremental benefits provided by local anesthetic infiltration between the popliteal artery and the capsule of the knee (IPACK), popliteal plexus block and genicular nerve block.

Erector spinae plane block: A narrative review with systematic analysis of the evidence pertaining to clinical indications and alternative truncal blocks.

STUDY OBJECTIVE: This narrative review discusses the anatomy, mechanism of action, techniques, pharmacology, indications, complications and substitutes for erector spinae plane (ESP) blocks. INTERVENTIONS: The Medline, Embase and Google Scholar databases (inception-last week of April 2020) were searched. For indications and alternative blocks, a systematic analysis of the available evidence was carried out. In order to highlight the best evidence available, only randomized trials with prospective registration, blinded assessment and sample size justification were retained for analysis. MAIN RESULTS: The collective body of anatomical studies suggests that ESP block may work through a combination of different mechanisms (e.g., local anesthetic spread to the thoracic paravertebral space, epidural space, and dorsal ramus). Compared to control, the available evidence suggests that ESP block results in decreased postoperative pain and opioid requirement for a wide array of thoracic and abdominal surgical interventions. Erector spinae plane blocks and thoracic paravertebral blocks seem to provide comparable benefits for thoracoscopic and breast cancer surgery when performed with a similar number of injections. Currently, ESP blocks should be favored over intercostal blocks since, at best, the latter provide similar analgesia to ESP blocks despite requiring multiple-level injections. CONCLUSIONS: In recent years, ESP blocks have become the topic of considerable clinical interest. Future trials are required to investigate their optimal technique, dose of local anesthetic and perineural adjuvants. Moreover, additional investigation should compare ESP blocks with robust multimodal analgesic regimens as well as truncal blocks such as thoracic epidural block, midpoint transverse process to pleura block, PECS block, quadratus lumborum block, and transversus abdominis plane block.