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BackgroundParavertebral and serratus plane blocks are both used to treat pain following breast surgery. However, it remains unknown if the newer serratus block provides comparable analgesia to the decades-old paravertebral technique.MethodsSubjects undergoing unilateral or bilateral non-mastectomy breast surgery were randomized to a single-injection serratus or paravertebral block in a subject-masked fashion (ropivacaine 0.5%; 20 mL unilateral; 16 mL/side bilateral). We hypothesized that (1) analgesia would be non-inferior in the recovery room with serratus blocks (measurement: Numeric Rating Scale), and (2) opioid consumption would be non-inferior with serratus blocks in the operating and recovery rooms. In order to claim that serratus blocks are non-inferior to paravertebral blocks, both hypotheses must be at least non-inferior.ResultsWithin the recovery room, pain scores for participants with serratus blocks (n=49) had a median (IQR) of 4.0 (0–5.5) vs 0 (0–3.0) for those with paravertebral blocks (n=51): 0.95% CI −3.00 to −0.00; p=0.001. However, the difference in morphine equivalents did not reach statistical significance for superiority with the serratus group consuming 14 mg (10–19) vs 10 mg (10–16) for the paravertebral group: 95% CI −4.50 to 0.00, p=0.123. Since the 95% CI lower limit of −4.5 was less than our prespecified margin of −2.0, we failed to conclude non-inferiority of the serratus block with regard to opioid consumption.ConclusionsSerratus blocks provided inferior analgesia compared with paravertebral blocks. Without a dramatic improvement in safety profile for serratus blocks, it appears that paravertebral blocks are superior to serratus blocks for postoperative analgesia after non-mastectomy breast surgery.Trial registration numberNCT03860974.

Author(s): Gabriel, Rodney A; Finneran, John J; Swisher, Matthew W; Said, Engy T; Sztain, Jacklynn F; Khatibi, Bahareh; Wallace, Anne M; Hosseini, Ava; Trescot, Andrea M; Ilfeld, Brian M | Abstract: BackgroundAcute post-mastectomy pain is frequently challenging to adequately treat with local anesthetic-based regional anesthesia techniques due to its relatively long duration measured in multiple weeks.CaseWe report three cases in which preoperative ultrasound-guided percutaneous intercostal nerve cryoneurolysis was performed to treat pain following mastectomy. Across all postoperative days and all three patients, the mean pain score on the numeric rating scale was 0 for each day. Similarly, no patient required any supplemental opioid analgesics during the entire postoperative period; and, no patient reported insomnia or awakenings due to pain at any time point. This was a significant improvement over historic cohorts.ConclusionsUltrasound-guided percutaneous cryoanalgesia is a potential novel analgesic modality for acute pain management which has a duration that better-matches mastectomy than other currently-described techniques. Appropriately powered randomized, controlled clinical trials are required to demonstrate and quantify both potential benefits and risks.

We tested the hypothesis that during a continuous popliteal-sciatic nerve block, postoperative analgesia is improved with the catheter insertion point "deep" to the paraneural sheath immediately distal to the bifurcation between the tibial and common peroneal branches, compared with the traditional approach "superficial" to the paraneural sheath proximal to the bifurcation. The needle tip location was determined to be accurately located with a fluid bolus visualized with ultrasound; however, catheters were subsequently inserted without a similar fluid injection and visualization protocol (visualized air injection was permitted and usually implemented, but not required per protocol). The average pain (0-10 scale) the morning after surgery for subjects with a catheter inserted at the proximal subparaneural location (n = 31) was a median (interquartile) of 1.5 (0.0-3.5) vs 1.5 (0.0-4.0) for subjects with a catheter inserted at the distal supraparaneural location (n = 32; P = .927). Secondary outcomes were similarly negative.

Continuous Popliteal Sciatic Blocks: Does Varying Perineural Catheter Location Relative to the Sciatic Bifurcation Influence Block Effects? A Dual-Center, Randomized, Subject-Masked, Controlled Clinical Trial Amanda M. Monahan, MD,* Sarah J. Madison, MD,* Vanessa J. Loland, MD,* Jacklynn F. Sztain, MD,* Michael L. Bishop, MD,* NavParkash S. Sandhu, MD,* Richard H. Bellars, MD,* Bahareh Khatibi, MD,* Alexandra K. Schwartz, MD,† Sonya S. Ahmed, MD,† Michael C. Donohue, PhD,‡ Scott T. Nomura, BS,§ Cindy H. Wen, BS,‖ and Brian M. Ilfeld, MD, MS*¶ BACKGROUND: Multiple studies have demonstrated that, for single-injection popliteal sciatic nerve blocks, block characteristics are dependent upon local anesthetic injection relative to the sciatic nerve bifurcation. In contrast, this relation remains unexamined for continuous pop- liteal sciatic nerve blocks. We, therefore, tested the hypothesis that postoperative analgesia is improved with the perineural catheter tip at the level of the bifurcation compared with 5 cm proximal to the bifurcation. METHODS: Preoperatively, subjects having moderately painful foot or ankle surgery were randomly assigned to receive an ultrasound-guided subepimyseal perineural catheter inserted either at or 5 cm proximal to the sciatic nerve bifurcation. Subjects received a single injection of mepivacaine 1.5% either via the insertion needle preoperatively or the perineural catheter postoperatively, fol- lowed by an infusion of ropivacaine 0.2% (6 mL/h basal, 4 mL bolus, and 30-min lockout) for the study duration. The primary end point was the average pain measured on a numeric rating scale (0–10) in the 3 hours before a data collection telephone call the morning after surgery. RESULTS: The average numeric rating scale of subjects with a catheter inserted at the sciatic nerve bifurcation (n = 64) was a median (10th, 25th to 75th, and 90th quartiles) of 3.0 (0.0, 2.4–5.0, and 7.0) vs 2.0 (0.0, 1.0–4.0, and 5.0) for subjects with a catheter inserted proximal to the bifurcation (n = 64; P = 0.008). Similarly, maximum pain scores were greater in the group at the bifurcation: 6.0 (3.0, 4.4–8.0, and 9.0) vs 5.0 (0.0, 3.0–8.0, and 10.0) (P = 0.019). Differences between the groups for catheter insertion time, opioid rescue dose, degree of numbness in the foot/toes, catheter dislodgement, and fluid leakage did not reach statistical significance. CONCLUSIONS: For continuous popliteal sciatic nerve blocks, a catheter inserted 5 cm proximal to the sciatic nerve bifurcation provides superior postoperative analgesia in subjects having moderately painful foot or ankle surgery compared with catheters located at the bifurcation. This is in marked contrast with single-injection popliteal sciatic nerve blocks for which benefits are afforded to local anesthetic injection distal, rather than proximal, to the bifurcation. (Anesth Analg 2016;122:1689–95) C ontinuous popliteal sciatic nerve blocks provide postoperative analgesia after surgical procedures of the foot and ankle. 1 The sciatic nerve courses down From the *Department of Anesthesiology, University of California San Diego, San Diego, California; †Department of Orthopedics, University of California San Diego, San Diego, California; ‡Division of Biostatistics and Bioinformat- ics, University of California San Diego, San Diego, ­California; §School of Med- icine, University of California San Diego, San Diego, C ­ alifornia; ‖Department of Ophthalmology, University of California San Diego, San Diego, California; and ¶Outcomes Research Consortium, Cleveland, Ohio. Accepted for publication December 28, 2015. Funding: Funding for this project was provided by the National Institutes of Health grant GM077026 (Principal Investigator: Dr. Ilfeld) from the National Institute of General Medical Sciences (Bethesda, Maryland); and the Department of Anesthesiology, University California San Diego (San Diego, California). The contents of this article are solely the responsibility of the authors and do not necessarily represent the official views of the funding entities. The authors declare no conflicts of interest. Reprints will not be available from the authors. Address correspondence to Brian M. Ilfeld, MD, MS, Department of ­Anesthesiology, University of California San Diego, 200 West Arbor Dr., MC 8770, San Diego, CA 92103. Address e-mail to bilfeld@ucsd.edu. Copyright © 2016 International Anesthesia Research Society DOI: 10.1213/ANE.0000000000001211 May 2016 • Volume 122 • Number 5 the posterior thigh and bifurcates just above or within the popliteal fossa into 2 branches: the tibial and common peroneal nerves. Cadaver studies have confirmed the location of this bifurcation to range from approximately 0 to 11 cm proximal to popliteal crease, most commonly 5 to 7 cm above the crease. 2,3 Using ultrasound guidance, practitioners can target a precise location along the sciatic nerve relative to the sciatic bifurcation for deposition of local anesthetic. 4–6 Previous randomized studies document that depositing an initial bolus of local anesthetic via a needle distal to the sciatic bifurcation—compared with proximal to the bifur- cation—results in decreased time to onset of sensory and motor block and at times an increased surgical-quality block success rate. 4–6 This suggests that deposition of local anes- thetic at various locations along the sciatic nerve can influ- ence block characteristics. However, findings from studies involving single-injection nerve blocks have not always been replicated when investigated in relation to continuous peripheral nerve blocks. 7–12 Whether the perineural catheter location relative to the sciatic nerve bifurcation influences www.anesthesia-analgesia.org 1689 Copyright © 2016 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.

Copyright © 2015, the American Society of Anesthesiologists, Inc. Wolters Kluwer Health, Inc. Background: The authors conducted a randomized, controlled, parallel-arm, superiority study to test the hypothesis that a continuous adductor canal block decreases the time to attain four discharge criteria compared with a continuous femoral nerve block after tricompartment knee arthroplasty. Methods: Subjects undergoing tricompartment knee arthroplasty were randomized using computer-generated lists to either an adductor canal or femoral perineural catheter (3-day ropivacaine 0.2% infusion) in an unmasked manner. The primary outcome was the time to attain four criteria: (1) adequate analgesia; (2) intravenous opioids independence; (3) ability to stand, walk 3 m, return, and sit down; and (4) ambulate 30 m. Results: Subjects with an adductor canal catheter (n = 39) reached all four criteria in a median of 55 h (interquartile, 42 to 63 h) compared with 61 h (49 to 69 h) for those with a femoral catheter (n = 41; 95% CI, -13 to 1 h; P = 0.12). The percentage of subjects who reached the two mobilization criteria on postoperative days 1 and 2 were 72 and 95% for those with an adductor canal catheter (n = 39), but only 27 and 76% in subjects with a femoral catheter (n = 41; both P < 0.001). Differences in pain scores at rest and intravenous opioid requirements were minimal, but femoral infusion improved dynamic analgesia (P = 0.01 to 0.02). Conclusion: Compared with a continuous femoral nerve block, a continuous adductor canal block did not appreciably decrease the time to overall discharge readiness even though it did decrease the time until adequate mobilization, primarily because both groups experienced similar analgesia and intravenous opioid requirements that-in most cases-exceeded the time to mobilization.

© 2015 American Society of Regional Anesthesia and Pain Medicine. Background We tested the hypothesis that, following unicompartment knee arthroplasty, a continuous adductor canal block decreases the time to reach 4 discharge criteria compared with a continuous femoral nerve block. Methods Subjects were randomized to either an adductor canal or femoral perineural catheter (2-day ropivacaine 0.2% infusion) in an unmasked fashion. The primary outcome was the time to attain 4 discharge criteria: (1) adequate analgesia; (2) intravenous opioid independence; (3) ability to independently stand, walk 3 m, return, and sit down; and (4) ambulate 30 m. Results Subjects with an adductor canal catheter (n = 15) reached all 4 criteria in a median of 35 hours (interquartile range, 24-43 hours), compared with 40 hours (interquartile range, 27-69 hours) for those with a femoral catheter (n = 15; Wilcoxon rank sum test: P = 0.46; log-rank test: P = 0.16). However, the percentages of subjects (adductor canal: femoral) who reached the 2 mobilization criteria were 27%:0% on postoperative day (POD) 0, 93%:53% on POD 1, and 100%:73% on POD 2. Of adductor canal subjects, 100% were discharge ready by POD 2, compared with only 73% of femoral subjects (P < 0.001). Conclusions Compared with a continuous femoral nerve block, a continuous adductor canal block did not appreciably decrease the median number of hours to overall discharge readiness, yet did decrease the number of discrete days until discharge readiness. These results are applicable to only unicompartment knee arthroplasty and must be considered preliminary because of the limited sample size of this pilot study.