Ultrasound-Guided Infraclavicular Brachial Plexus Block: Prospective Randomized Comparison of the Lateral Sagittal and Costoclavicular Approach

Background and Objectives It has recently been proposed that an infraclavicular brachial plexus block (BPB) at the costoclavicular (CC) space may overcome some of the limitations of the lateral sagittal (LS) approach. In this study, we hypothesized that the CC approach will produce faster onset of sensory blockade of the 4 major terminal nerves of the brachial plexus than the LS approach. Methods Forty patients undergoing elective upper extremity surgery under a BPB were randomized to receive either the LS (Gp-LS, n = 20) or CC approach (Gp-CC, n = 20) for infraclavicular BPB. Twenty-five milliliters of 0.5% ropivacaine was used for the BPB in both study groups. Sensory-motor blockade of the ipsilateral median, radial, ulnar, and musculocutaneous nerves was assessed by a blinded observer at regular intervals for 45 minutes after the block. Sensory block was assessed using a verbal rating scale (0–100) and motor block using a 3-point qualitative scale (0–2). Onset of sensory (primary outcome variable) and motor blockade was defined as the time it took to achieve a sensory verbal rating scale of 30 or less and motor grade of 1 or less, respectively. Time to readiness for surgery was defined as the time it took to achieve a sensory score of 30 or less and motor grade of 1 or less in all the 4 nerves tested. Results The overall sensory onset time (median [interquartile range]) was significantly faster (P = 0.004) in Gp-CC (10 [10–26.25] minutes) than in Gp-LS (20 [15–30] minutes). The overall sensory score was significantly lower in Gp-CC than in Gp-LS at 5 (P

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Lack of Association Between Levels and Length of Intraoperative Controlled Hypotension and Acute Kidney Injury in Total Hip Arthroplasty Patients Receiving Neuraxial Anesthesia

Background and Objectives Previous research suggests that increased duration and lower levels of intraoperative hypotension (IOH) are associated with postoperative acute kidney injury (AKI). However, this association has not been evaluated in the context of intraoperative controlled hypotension (IOCH), a practice that has been linked in the past to improved outcomes with respect to blood loss and transfusion needs. This study aimed to investigate whether IOCH is associated with postoperative AKI among total hip arthroplasty patients at an institution where this technique is commonly practiced. Methods We performed a retrospective cohort study of 2431 unilateral total hip arthroplasty patients who received IOCH under neuraxial anesthesia as well as invasive arterial monitoring between March 2016 and January 2017. Multiple logistic regression was used to compute the adjusted odds ratios of postoperative AKI, adjusting for covariates including duration of intraoperative mean arterial pressure of less than 60 mm Hg. Sensitivity analyses also considered the effects of IOH defined at mean arterial pressure of less than 55 and less than 65 mm Hg. Results Acute kidney injury occurred in 45 (1.85%) of the 2431 patients in this cohort. Longer duration of hypotension was not associated with increased odds of postoperative AKI. Preexisting differences, such as compromised renal function, best predicted increased odds of AKI. Conclusions In this study, AKI was rare. We found a lack of association between IOH and postoperative AKI in a setting where neuraxial anesthesia–facilitated IOCH is routinely practiced. Therefore, it seems prudent for future research and clinical guidelines to consider the distinction between inadvertent and controlled hypotension. Accepted for publication February 11, 2018. Address correspondence to: Stavros G. Memtsoudis, MD, PhD, FCCP, Department of Anesthesiology, Hospital for Special Surgery, 535 E 70th St, New York, NY 10021 (e-mail: memtsoudiss@hss.edu). This study was internally funded by the Department of Anesthesiology, Hospital for Special Surgery, New York, NY. J.T.Y. is coinvestigator on a project about intravenous acetaminophen for postoperative analgesia funded by Mallinckrodt and performs editorial board activity for Anesthesia & Analgesia and Regional Anesthesia and Pain Medicine. S.G.M. is a director on the boards of the American Society of Regional Anesthesia and Pain Medicine and the Society of Anesthesia and Sleep Medicine. He is a one-time consultant for Sandoz Inc. and the holder of US Patent US-2017-0361063, Multicatheter Infusion System. He is the owner of SGM Consulting, LLC and co-owner of FC Monmouth, LLC. None of the above relations influenced the conduct of the present study. S.M.W. declares no conflict of interest. Author Contributions: S.M.W. helped design the study, analyze the data, and write the manuscript. J.T.Y. helped design the study, analyze the data, and write the manuscript. S.G.M. helped design the study, analyze the data, and write the manuscript. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.rapm.org). Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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A Cadaver Study Investigating Structures Encountered by the Needle During a Retroclavicular Approach to Infraclavicular Brachial Plexus Block

Background and Objectives Retroclavicular block is designed to overcome the negative aspects of the commonly utilized ultrasound-guided parasagittal approach to the infraclavicular block. However, this approach necessitates the needle traversing an area posterior to the clavicle inaccessible to ultrasound wave conduction. This study sought to document the structures vulnerable to needle injury during a retroclavicular block. Methods A Tuohy needle was inserted using a retroclavicular approach to the infraclavicular block in 3 lightly embalmed cadavers followed by a catheter insertion 4 cm beyond the needle tip. The process was repeated on the contralateral side. With the needle and catheter in position, the cadavers were dissected and photographed. Results In 4 of the 6 dissections, the needle was directly touching the suprascapular nerve deep to the clavicle. In the remaining 2 dissections, the suprascapular nerve was within 2 cm of the needle. In 1 dissection, the suprascapular vein was indented, behind the clavicle. The trapezius was the only muscle layer traversed by the needle in all dissections. In 3 of the 6 dissections, the catheter penetrated the posterior cord. In the remaining 3, the catheter threaded along the neurovascular bundle. Conclusions The suprascapular nerve is consistently in the path of the block needle posterior to the clavicle. This raises the possibility of risk of injury to the suprascapular nerve when using this approach to the brachial plexus. Vascular injury is also possible deep to the clavicle, and because of the noncompressible location, caution is advised in patients with disordered coagulation. Accepted for publication March 10, 2018. S.F.S. is now with the Department of Anesthesiology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada. Address correspondence to: Vishal Uppal, DA, EDRA, FRCA, Department of Anesthesia, Perioperative Medicine and Pain Management, Dalhousie University, Nova Scotia Health Authority and IWK Health Centre, Halifax, Nova Scotia, Canada B3H 2Y9 (e-mail: v.uppal@dal.ca). No external funds were obtained for the study. Internal departmental funds were used. V.U. has been a principal investigator for a Recro Pharma (Devault, PA)–funded clinical trial involving intravenous meloxicam in Halifax, Nova Scotia, Canada. This conflict does not directly or indirectly affect the conduct or reporting of this study. The authors declare no conflict of interest. Author contributions: Study design/planning: all authors; study conduct: S.F.S., V.U., R.S.; writing of the paper: S.F.S., V.U; revision of the manuscript: all authors. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.rapm.org). Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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Ketamine for Refractory Headache: A Retrospective Analysis

Background and Objectives The burden of chronic headache disorders in the United States is substantial. Some patients are treatment refractory. Ketamine, an N-methyl-D-aspartate antagonist, provides potent analgesia in subanesthetic doses in chronic pain, and limited data suggest it may alleviate headache in some patients. Methods We performed a retrospective study of 61 patients admitted over 3 years for 5 days of intravenous therapy that included continuous ketamine to determine responder rate and patient and ketamine infusion characteristics. Pain ratings at 2 follow-up visits were recorded. An immediate responder was a patient with decrease of 2 points or greater in the numerical rating scale (0–10) from start to final pain in the hospital. Sustained response at office visits 1 and 2 was determined based on maintaining the 2-point improvement at those visits. Patients were assessed daily for pain and adverse events (AEs). Results Forty-eight (77%) of the 61 patients were immediate responders. There were no differences regarding demographics, opioid use, or fibromyalgia between immediate responders and nonresponders. Maximum improvement occurred 4.56 days (mean) into treatment. Sustained response occurred in 40% of patients at visit 1 (mean, 38.1 days) and 39% of patients at visit 2 (mean, 101.3 days). The mean maximum ketamine rate was 65.2 ± 2.8 mg/h (0.76 mg/kg per hour). Ketamine rates did not differ between groups. Adverse events occurred equally in responders and nonresponders and were mild. Conclusions Ketamine was associated with short-term analgesia in many refractory headache patients with tolerable adverse events. A prospective study is warranted to confirm this and elucidate responder characteristics. Accepted for publication March 25, 2018. Address correspondence to: Eric S. Schwenk, MD, Department of Anesthesiology, Sidney Kimmel Medical College at Thomas Jefferson University, Suite 8130, Gibbon Bldg, 111 South 11th St, Philadelphia, PA 19107 (e-mail: Eric.Schwenk@jefferson.edu). E.S.S. has received consulting fees from Avenue Therapeutics. C.G.L. has received honoraria from Cefaly Technology. S.D.S. receives, or has received, honoraria from Alder Biopharmaceuticals; Allergan, Inc; Amgen; Avanir Pharmaceuticals, Inc; Curelator, Inc; Dr Reddy's Laboratories; eNeura Inc; electroCore Medical, LLC; Lilly USA, LLC; Medscape, LLC; NINDS; Supernus Pharmaceuticals, Inc; Teva Pharmaceuticals; Theranica; and Trigemina, Inc. W.Y. has received consulting fees from Allergan; he is on the advisory board for Amgen, Avanir, Cipla, Alder, Eli Lilly, and Supernus. He has received research support from Allergan, Amgen, Autonomic Technologies, Colucis, Cumberland, Dr Reddy's Laboratories, Eli Lilly, Novartis, PCORI, Scion, Teva, and Zosano. Eugene Viscusi has served as a consultant for AcelRx, Medicines Company, Mallinkrodt, Trevena, Cara Pharmaceuticals, Salix, AstraZeneca, and Merck. His institution has received research grants in the past from AcelRx, Adolor, Progenics, and Pacira. He has been a paid lecturer for AcelRx, Merck, Salix, and Mallinkrodt. None of these companies were involved in any aspect of the development of this manuscript. A.C.D., A.R., M.C.T., and M.G.H. declare no conflict of interest. Institutional affiliation of manuscript: Department of Anesthesiology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA. Source of funding: Departmental funding. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.rapm.org). Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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Hypertonic Sodium Chloride Preinjectate Increases In Vivo Radiofrequency Ablation Size: Histological and Magnetic Resonance Imaging Findings

Background and Objectives Emphasis has been placed on methods to enlarge monopolar radiofrequency (RF) lesion size for pain management. Ex vivo research has suggested that fluid modulation may be an effective method to enlarge lesion zone. To date, these findings have not been confirmed in vivo. The purpose of this study was to determine the effect of hypertonic saline on in vivo lesion size through both histological and magnetic resonance imaging (MRI) analysis. A secondary purpose was to validate in vivo characterization of RF lesions using contrast-enhanced MRI. Methods Monopolar RF was performed in an in vivo porcine model in 3 groups: (1) without fluid preinjection, (2) with preinjection of 1% lidocaine, or (3) with preinjection of 1% lidocaine and 8% sodium chloride. Following lesioning, MRI processing with gadolinium-enhanced, T1-weighted imaging and histological analysis was performed. Results The addition of 8% sodium chloride significantly increased the size of RF lesion in comparison to the addition of 1% lidocaine alone and to the absence of fluid injection, as assessed by histological and MRI analysis. Three distinct histological lesion zones were identified. In comparison to the no-fluid group, the addition of hypertonic saline significantly altered the shape and histological composition of the lesion. There was a significant correlation of lesion volume as assessed by MRI and by histology measurements. Peak power and total energy delivery also correlated with lesion size. Conclusions This study validates the ability of hypertonic saline to increase in vivo RF lesion size. With further refinement, MRI may be a viable method to assess RF lesion size. Accepted for publication March 28, 2018. Address correspondence to: David A. Provenzano, MD, Pain Diagnostics and Interventional Care, 301 Ohio River Blvd, Suite 203, Edgeworth Medical Commons, Sewickley, PA 15143 (e-mail: davidprovenzano@hotmail.com). This study was supported by Medtronic. This study was conducted at the Medtronic Physiological Research Laboratory. Medtronic PLC provided funding for animal acquisition and supplies. No monetary compensation was provided to any of the investigators for their participation in this nonclinical research. This work was presented in part at the American Academy of Pain Medicine 33th Annual Meeting, Orlando, FL, April 2017; and the American Society of Regional Anesthesia and Pain Medicine 15th Annual Meeting, San Diego, CA, November 2016. D.A.P. is a consultant for Bioness, Boston Scientific, Halyard, Medtronic, Nevro, Sollis, and Abbott. He receives research support from Medtronic and Abbott. D.A.P. received no funding or reimbursement for his work on this project. J.T.W. is an employee of Medtronic. E.R.C. is an employee of Boston Scientific. Cosman Medical is a wholly owned subsidiary of Boston Scientific. Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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Is a Retrolaminar Approach to the Thoracic Paravertebral Space Possible?: A Human Cadaveric Study

Background and Objectives The retrolaminar block (RB) is used for truncal analgesia, but its mechanism of neural blockade remains obscure. We sought to learn the pattern of local anesthetic spread after thoracic RB using cadaveric models. Methods In 8 fresh cadavers, an ultrasound-guided T4 RB was performed with 20 mL of methylene blue 1% and bupivacaine 0.5%. For comparison, an RB at T9 in 1 cadaver and a T4 thoracic paravertebral block in another cadaver were performed. Subsequently, posterior and anterior thoracic dissections were performed to examination where the dye spread. Results After T4 RB, dye was noted to spread in the ipsilateral retrolaminar plane (all 8 cadavers, median cephalad spread 3.5 cm, caudad spread 10.7 cm, lateral spread 2.5 cm), the contralateral retrolaminar plane (6 cadavers), the paravertebral space (5 cadavers, median of 3 segments, T3–T5), the intercostal space (5 cadavers, median of 3.5 cm laterally), the T4 epidural space (6 cadavers), and the intervertebral foramina (4 cadavers, median of 2 segments, T4–T5). After T9 retrolaminar injection, dye was noted in the ipsilateral retrolaminar plane (5.5 cm cephalad, 13.5 cm caudad, and 2.5 cm lateral), the contralateral retrolaminar plane, and the epidural space. Dye after T4 traditional paravertebral block spread to T1–T6 paravertebral space with 15-cm lateral spread. Conclusions Injectate spread to the paravertebral space, epidural space, intercostal space, and intervertebral foramina is possible in the RB but is quite variable. In comparison to the thoracic paravertebral block, injectate spread within the paravertebral space is more limited. Accepted for publication April 23, 2018. Address correspondence to: A. Sassan Sabouri, MD, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 55 Fruit St, GRJ 446, Boston, MA 02114 (e-mail: asabouri@mgh.harvard.edu). This work is attributed to the Department of Anesthesiology, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA. This study was supported by DACCPM Clinical Pilot Grant (no. 1200-218309). Primary results of this study were presented at the 41st American Society of Regional Anesthesia Annual Regional Anesthesia and Acute Pain Medicine Meeting, New Orleans, LA, as a poster presentation on April 2, 2016, and final results were presented as a poster at the Department of Anesthesia, Critical Care and Pain Medicine Research Day, Massachusetts General Hospital, Boston, MA, on October 18, 2017. The authors declare no conflict of interest. Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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Lipid Emulsion Pretreatment Decreased the Maximum Total and Free Plasma Concentration of Levobupivacaine for Femoral and Sciatic Nerve Block in Below-Knee Fracture Surgery

Background and Objectives Although intravenous lipid emulsion has been proved a powerful antidote for local anesthetic toxicity, there are few pharmacokinetic data on using lipid infusion as a pretreatment for other clinical applications. We assessed the influence of lipid pretreatment on the pharmacodynamics and pharmacokinetics of levobupivacaine. Methods Altogether, 12 patients undergoing below-knee surgery for a fracture were randomly assigned to 2 groups (6 patients per group): pretreatment with 1.5 mL/kg lipid infusion (lipid group) or saline infusion (control subjects) followed by complete femoral and sciatic nerve block with 0.375% levobupivacaine (2.5 mg/kg). Total and free (non–protein bound) plasma levobupivacaine concentrations and triglycerides in the lipid group were determined. Results Results were given as means ± SD. Total and free maximum plasma levobupivacaine concentrations were lower in the lipid group than in control subjects (865 ± 98 vs 1145 ± 177 μg/L and 56.8 ± 7.5 vs 78.2 ± 13.7 μg/L, respectively; P

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