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Background Percutaneous auricular nerve stimulation (neuromodulation) involves implanting electrodes around the ear and administering an electric current. A device is currently available within the USA cleared to treat symptoms from opioid withdrawal, and multiple reports suggest a possible postoperative analgesic effect. The current randomized controlled pilot study was undertaken to (1) determine the feasibility and optimize the protocol for a subsequent definitive clinical trial; and (2) estimate the treatment effect of auricular neuromodulation on postoperative pain and opioid consumption following two ambulatory surgical procedures. Methods Within the recovery room following cholecystectomy or hernia repair, an auricular neuromodulation device (NSS-2 Bridge, Masimo, Irvine, California, USA) was applied. Participants were randomized to 5 days of either electrical stimulation or sham in a double-blinded fashion. Results In the first 5 days, the median (IQR) pain level for active stimulation (n=15) was 0.6 (0.3-2.4) vs 2.6 (1.1-3.7) for the sham group (n=15) (p=0.041). Concurrently, the median oxycodone use for the active stimulation group was 0 mg (0-1), compared with 0 mg (0-3) for the sham group (p=0.524). Regarding the highest pain level experienced over the entire 8-day study period, only one participant (7%) who received active stimulation experienced severe pain, versus seven (47%) in those given sham (p=0.031). Conclusions Percutaneous auricular neuromodulation reduced pain scores but not opioid requirements during the initial week after cholecystectomy and hernia repair. Given the ease of application as well as a lack of systemic side effects and reported complications, a definitive clinical trial appears warranted. Trial registration number NCT05521516. [ABSTRACT FROM AUTHOR]

Introduction We previously reported that a 6-day continuous peripheral nerve block reduces established postamputation phantom pain. To provide patients and providers with the information to best inform treatment decisions, here we reanalyze the data and present the results in a more patient-centered format. We also provide information on patient-defined clinically relevant benefits to facilitate evaluation of available studies and guide future trial design. Methods The original trial enrolled participants with a limb amputation and phantom pain who were randomized to receive a 6-day continuous peripheral nerve block(s) of either ropivacaine (n=71) or saline (n=73) in a double-masked fashion. Here we calculate the percentage of each treatment group that experienced a clinically relevant improvement as defined by previous studies as well as present what the participants of our study defined as small, medium, and large analgesic improvements using the 7-point ordinal Patient Global Impression of Change scale. Results Among patients who were given a 6-day ropivacaine infusion, 57% experienced at least a 2-point improvement on the 11-point numeric rating scale in their average and worst phantom pain 4 weeks postbaseline as compared with 26% (p<0.001) for average and 25% (p<0.001) for worst pain in patients given a placebo infusion. At 4 weeks, the percentage of participants rating their pain as improved was 53% for the active vs 30% for the placebo groups (95% CI 1.7 (1.1, 2.7), p=0.008). For all patients combined, the median (IQR) phantom pain Numeric Rating Scale improvements at 4 weeks considered small, medium, and large were 2 (0-2), 3 (2-5), and 5 (3-7), respectively. The median improvements in the Brief Pain Inventory interference subscale (0-70) associated with small, medium, and large analgesic changes were 8 (1-18), 22 (14-31), and 39 (26-47). Conclusions Among patients with postamputation phantom pain, a continuous peripheral nerve block more than doubles the chance of a clinically relevant improvement in pain intensity. Amputees with phantom and/or residual limb pain rate analgesic improvements as clinically relevant similarly to other chronic pain etiologies, although their smallest relevant improvement in the Brief Pain Inventory was significantly larger than previously published values. [ABSTRACT FROM AUTHOR]

Background: Following outpatient surgery, it is often difficult to provide adequate analgesia while concurrently minimizing opioid requirements. Ultrasound-guided percutaneous peripheral nerve stimulation has been proposed as an analgesic, but requires physician-level skills, advanced equipment, up to an hour to administer, and is frequently cost prohibitive. In contrast, percutaneous auricular neuromodulation may be placed by nursing staff in a few minutes without additional equipment, theoretically provides analgesia for nearly any anatomic location, lacks systemic side effects, and has no significant risks. We now present a case report to demonstrate proof of concept for the off-label use of an auricular neuromodulation device-originally developed to treat symptoms associated with opioid withdrawal-to instead provide analgesia following outpatient surgery.Case Presentation: Following moderately painful ambulatory orthopedic and breast surgery, seven patients had an auricular neuromodulation device (NSS-2 Bridge, Masimo, Irvine, California, USA) affixed within the recovery room in approximately 5 min and discharged home. Average resting and dynamic pain scores measured on the 0-10 Numeric Rating Scale were a median of 1 over the first 2 days, subsequently falling to 0. Five patients avoided opioid use entirely, while the remaining two each consumed 5 mg of oxycodone during the first 1-2 postoperative days. After 5 days, the devices were removed at home and discarded.Conclusions: These cases demonstrate that ambulatory percutaneous auricular neuromodulation is feasible and may be an effective analgesic and decreasing or even negating opioid requirements following outpatient surgery. Considering the lack of systemic side effects, serious adverse events, and misuse/dependence/diversion potential, further study with a randomized, controlled trial appears warranted. [ABSTRACT FROM AUTHOR]

Background: Paravertebral 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.Methods: Subjects 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.Results: Within 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.Conclusions: Serratus 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 Number: NCT03860974. [ABSTRACT FROM AUTHOR]

Background: Cryoneurolysis of peripheral nerves uses localised intense cold to induce a prolonged block over multiple weeks that has the promise of providing potent analgesia outlasting the duration of postoperative pain following surgery, as well as treat other acute and chronic pain states. However, it remains unclear whether persistent functional motor deficits remain following cryoneurolysis of mixed sensorimotor peripheral nerves, greatly limiting clinical application of this modality. To help inform future research, we used a rat peroneal nerve injury model to evaluate if cryoneurolysis results in persistent deficits in motor function.Methods: Male Lewis rats (n=30) had their common peroneal nerves exposed bilaterally at the proximal lateral margin of the knee and subsequently underwent cryoneurolysis on one limb and sham treatment on the contralateral limb. Outcomes were evaluated on days 3, 14, 30, 90 and 180. The primary end point was motor function, based on ankle dorsiflexion torque. In addition, sensory function was tested based on von Frey's filament sensitivity to the peroneal sensory distribution. A subset of animals was sacrificed following functional testing at each time point, and general tissue morphology, connective tissue deposition, and axon counts were evaluated.Results: Motor deficits in treated limbs were observed at 3 and 14 days but had resolved at time points beyond 1 month. Bilateral sensory deficits were also observed at 3 and 14 days, and also resolved within 1 month. Consistent with motor functional deficits, axon counts trended lower in treated nerves compared with contralateral controls at 3 days; however, axon counts were not significantly different at later time points.Conclusions: When applied to a mixed sensorimotor nerve, cryoneurolysis did not result in persistent motor deficits. [ABSTRACT FROM AUTHOR]

Background: Paravertebral nerve blocks (PVBs) are frequently used to treat pain during and following breast surgery, but have various undesirable risks such as pneumothorax. The erector spinae plane block (ESPB) also provides perioperative breast analgesia, but is purported to be easier to administer with a favorable safety profile. However, it remains unknown if the new ESPB provides comparable analgesia as the decades-old PVB technique.Methods: Subjects undergoing unilateral or bilateral non-mastectomy breast surgery were randomized to a single-injection ESPB or PVB in a subject-blinded fashion (ropivacaine 0.5% with epinephrine; 20 mL unilateral or 16 mL/side for bilateral). We hypothesized that (1) analgesia would be non-inferior in the recovery room as measured on a Numeric Rating Scale (NRS) with ESPB, and (2) opioid consumption would be non-inferior in the operating and recovery rooms with ESPB.Results: Both pain scores and opioid consumption were higher in subjects with ESPBs (n=50) than PVBs (n=50; median NRS 3.0 vs 0; 95% CI -3.0 to 0; p=0.0011; and median morphine equivalents 2.0 vs 1.5 mg; 95% CI -1.2 to -0.1; p=0.0043). No block-related adverse events occurred in either group.Conclusions: PVBs provided superior analgesia and reduced opioid requirements following non-mastectomy breast surgery. To compare the relatively rare complications between the techniques will require a sample size 1-2 orders of magnitude greater than the current investigation; however, without a dramatic improvement in safety profile for ESPBs, it appears that PVBs are superior to ESPBs for postoperative analgesia after non-mastectomy breast surgery.Trial Registration Number: NCT03549234. [ABSTRACT FROM AUTHOR]

Introduction Peripheral nerve stimulation (PNS) has historically been used to treat chronic pain, but generally requires implantation of a permanent system for sustained relief. A recent study found that a 60-day PNS treatment decreases post-amputation pain, and the current work investigates longer-term outcomes out to 12 months in the same cohort. Methods As previously reported, 28 traumatic lower extremity amputees with residual and/or phantom limb pain were randomized to receive 8 weeks of PNS (group 1) or 4 weeks of placebo followed by a crossover 4 weeks of PNS (group 2). Percutaneous leads were implanted under ultrasound guidance targeting the femoral and sciatic nerves. During follow-up, changes in average pain and pain interference were assessed using the Brief Pain Inventory-Short Form and comparing with baseline. Results Significantly more participants in group 1 reported =50% reductions in average weekly pain at 12 months (67%, 6/9) compared with group 2 at the end of the placebo period (0%, 0/14, p=0.001). Similarly, 56% (5/9) of participants in group 1 reported =50% reductions in pain interference at 12 months, compared with 2/13 (15%, p=0.074) in group 2 at crossover. Reductions in depression were also statistically significantly greater at 12 months in group 1 compared with group 2 at crossover. Conclusions This work suggests that percutaneous PNS delivered over a 60-day period may provide significant carry-over effects including pain relief, potentially avoiding the need for a permanently implanted system while enabling improved function in patients with chronic pain. [ABSTRACT FROM AUTHOR]

Background: We tested the joint hypotheses that both perineural and systemic dexmedetomidine prolong the duration of an ulnar nerve block (UNB) compared with ropivacaine alone and that systemic dexmedetomidine is noninferior compared with perineural dexmedetomidine in block prolongation.Methods: We performed bilateral UNBs in 22 healthy volunteers on two separate days. On the first day, each arm was randomized to either 4 mL ropivacaine 5 mg/mL+1 mL dexmedetomidine 100 µg/mL (Perineural) or 4 mL ropivacaine 5 mg/mL+1 mL saline (Systemic). On the subsequent treatment day, each arm was randomized to 1 mL of saline plus 4 mL of ropivacaine at either 7.5 mg/mL(HiRopi) or 5 mg/mL (NoDex). The primary outcome measure was the duration of sensory block assessed by mechanical discrimination.Results: Mean sensory block duration was longer in both the Perineural (14.4 hours, 95% CI 13.1 to 15.6) and Systemic treatments (9.2 hours, 95% CI 8.6 to 9.8) compared with the NoDex treatment (7.1 hours, 95% CI 6.6 to 7.6) (p<0.0001 for both). Systemic dexmedetomidine was inferior (not noninferior) compared with perineural dexmedetomidine, as the 95% CI of the difference (mean difference 5.2 hour, 95% CI 4.2 to 6.1) exceeded the noninferiority limit of 3.6 hour. Onset time did not differ among the groups. The other test modalities demonstrated similar block durations as the primary outcome.Conclusions: Adding dexmedetomidine perineurally to ropivacaine doubles the duration of an UNB. Systemic dexmedetomidine also prolongs the duration of UNB, but has less of an effect compared with the perineural route.Trial Registration Number: NCT03222323. [ABSTRACT FROM AUTHOR]

Background and Objectives: Percutaneous peripheral nerve stimulation (PNS) is an analgesic modality involving the insertion of a lead through an introducing needle followed by the delivery of electric current. This modality has been reported to treat chronic pain as well as postoperative pain following knee and foot surgery. However, it remains unknown if this analgesic technique may be used in ambulatory patients following upper extremity surgery. The purpose of this proof-of-concept study was to investigate various lead implantation locations and evaluate the feasibility of using percutaneous brachial plexus PNS to treat surgical pain following ambulatory rotator cuff repair in the immediate postoperative period.Methods: Preoperatively, an electrical lead (SPR Therapeutics, Cleveland, Ohio) was percutaneously implanted to target the suprascapular nerve or brachial plexus roots or trunks using ultrasound guidance. Postoperatively, subjects received 5 min of either stimulation or sham in a randomized, double-masked fashion followed by a 5 min crossover period, and then continuous stimulation until lead removal postoperative days 14-28.Results: Leads (n=2) implanted at the suprascapular notch did not appear to provide analgesia, and subsequent leads (n=14) were inserted through the middle scalene muscle and placed to target the brachial plexus. Three subjects withdrew prior to data collection. Within the recovery room, stimulation did not decrease pain scores during the first 40 min of the remaining subjects with brachial plexus leads, regardless of which treatment subjects were randomized to initially. Seven of these 11 subjects required a single-injection interscalene nerve block for rescue analgesia prior to discharge. However, subsequent average resting and dynamic pain scores postoperative days 1-14 had a median of 1 or less on the Numeric Rating Scale, and opioid requirements averaged less than 1 tablet daily with active stimulation. Two leads dislodged during use and four fractured on withdrawal, but no infections, nerve injuries, or adverse sequelae were reported.Conclusions: This proof-of-concept study demonstrates that ultrasound-guided percutaneous PNS of the brachial plexus is feasible for ambulatory shoulder surgery, and although analgesia immediately following surgery does not appear to be as potent as local anesthetic-based peripheral nerve blocks, the study suggests that this modality may provide analgesia and decrease opioid requirements in the days following rotator cuff repair. Therefore, it suggests that a subsequent, large, randomized clinical trial with an adequate control group is warranted to further investigate this therapy in the management of surgical pain in the immediate postoperative period. However, multiple technical issues remain to be resolved, such as the optimal lead location, insertion technique, and stimulating protocol, as well as preventing lead dislodgment and fracture.Trial Registration Number: NCT02898103. [ABSTRACT FROM AUTHOR]

Background and Objectives: Percutaneous peripheral nerve stimulation (PNS) is an analgesic modality involving the insertion of a lead through an introducing needle followed by the delivery of electric current. This modality has been reported to treat chronic pain as well as postoperative pain the day following knee surgery. However, it remains unknown if this analgesic technique may be used in ambulatory subjects following foot procedures beginning within the recovery room immediately following surgery, and with only short series of patients reported to date, the only available data are derived from strictly observational studies. The purposes of this proof-of-concept study were to demonstrate the feasibility of using percutaneous sciatic nerve PNS to treat postoperative pain following ambulatory foot surgery in the immediate postoperative period and provide the first available data from a randomized controlled study design to provide evidence of analgesic effect.Methods: Preoperatively, an electrical lead (SPRINT; SPR Therapeutics, Inc, Cleveland, Ohio) was percutaneously inserted posterior to the sciatic nerve between the subgluteal region and bifurcation with ultrasound guidance. Following hallux valgus osteotomy, subjects received 5 minutes of either stimulation or sham in a randomized, double-masked fashion followed by a 5-minute crossover period and then continuous stimulation until lead removal on postoperative days 14 to 28.Results: During the initial 5-minute treatment period, subjects randomized to stimulation (n = 4) experienced a downward trajectory in their pain over the 5 minutes of treatment, whereas those receiving sham (n = 3) reported no such change until their subsequent 5-minute stimulation crossover. During the subsequent 30 minutes of stimulation, pain scores decreased to 52% of baseline (n = 7). Three subjects (43%) used a continuous popliteal nerve block for rescue analgesia during postoperative days 0 to 3. Overall, resting and dynamic pain scores averaged less than 1 on the numeric rating scale, and opioid use averaged less than 1 tablet daily with active stimulation. One lead dislodged, 2 fractured during use, and 1 fractured during intentional withdrawal.Conclusions: This proof-of-concept study demonstrates that percutaneous sciatic nerve PNS is feasible for ambulatory foot surgery and suggests that this modality provides analgesia and decreases opioid requirements following hallux valgus procedures. However, lead dislodgement and fracture are concerns.Clinical Trial Registration: This study was registered at Clinicaltrials.gov, identifier NCT02898103. [ABSTRACT FROM AUTHOR]

In 2014, the American Society of Regional Anesthesia and Pain Medicine in collaboration with the European Society of Regional Anaesthesia and Pain Therapy convened a group of experts to compare pathways for anesthetic and analgesic management for patients undergoing total knee arthroplasty in North America and Europe and to develop a practice pathway. This review is intended to be an analysis of the current literature to assist individuals and institutions in designing a pathway for total knee arthroplasty that is based on existing evidence and expert recommendation and may be customized according to individual settings. [ABSTRACT FROM AUTHOR]

Background: Liposome bupivacaine (Exparel) is a multivesicular liposomal formulation of bupivacaine currently approved in the United States for single-dose administration into the surgical site to provide postsurgical analgesia. This retrospective analysis examined safety data from clinical trials involving the off-label use of this formulation in peripheral nerve blocks.Methods: Data from 6 controlled (phases I-III) studies were compiled involving single-injection ankle, femoral nerve, and intercostal nerve blocks (2 each). Adverse events (AEs) were monitored for 1 to 30 days after study drug administration.Results: Of 575 subjects, 335 received liposome bupivacaine (2-310 mg), 33 received bupivacaine HCl (75-125 mg), and 207 received normal saline (placebo). Overall, 76% of subjects receiving liposome bupivacaine experienced 1 or more AEs compared with 61% receiving bupivacaine HCl and 76% receiving placebo. The most frequently reported AEs among subjects receiving liposome bupivacaine were nausea, pyrexia, pruritus, constipation, and vomiting. The most common treatment-related AE was hypesthesia among subjects treated with liposome bupivacaine or bupivacaine HCl. Incidence of nervous system AEs for liposome bupivacaine, bupivacaine HCl, and placebo was 21%, 27%, and 21%, respectively. Similarly, incidence of cardiac AEs was 9%, 0%, and 12%, respectively. At least 1 serious AE occurred in 8% of subjects receiving liposome bupivacaine compared with 10% of those receiving placebo (none assessed by investigators as related to study medication).Conclusions: Liposome bupivacaine has a similar safety and side effect profile to bupivacaine HCl and normal saline, suggesting that most of the more common AEs are related to either opioid rescue or the surgical procedure itself. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: We aimed to determine with this randomized, triple-masked, placebo-controlled study if benefits are afforded by adding a multiple-day, ambulatory, continuous ropivacaine paravertebral nerve block to a single-injection ropivacaine paravertebral block after mastectomy.Methods: Preoperatively, 60 subjects undergoing unilateral (n = 24) or bilateral (n = 36) mastectomy received either unilateral or bilateral paravertebral perineural catheter(s), respectively, inserted between the third and fourth thoracic transverse process(es). All subjects received an initial bolus of ropivacaine 0.5% (15 mL) via the catheter(s). Subjects were randomized to receive either perineural ropivacaine 0.4% or normal saline using portable infusion pump(s) [5 mL/h basal; 300 mL reservoir(s)]. Subjects remained hospitalized for at least 1 night and were subsequently discharged home where the catheter(s) were removed on postoperative day (POD) 3. Subjects were contacted by telephone on PODs 1, 4, 8, and 28. The primary end point was average pain (scale, 0-10) queried on POD 1.Results: Average pain queried on POD 1 for subjects receiving perineural ropivacaine (n = 30) was a median (interquartile) of 2 (0-3), compared with 4 (1-5) for subjects receiving saline (n = 30; 95% confidence interval difference in medians, -4.0 to -0.3; P = 0.021]. During this same period, subjects receiving ropivacaine experienced a lower severity of breakthrough pain (5 [3-6] vs 7 [5-8]; P = 0.046) as well. As a result, subjects receiving perineural ropivacaine experienced less pain-induced physical and emotional dysfunction, as measured with the Brief Pain Inventory (lower score = less dysfunction): 14 (4-37) versus 57 (8-67) for subjects receiving perineural saline (P = 0.012). For the subscale that measures the degree of interference of pain on 7 domains, such as general activity and relationships, subjects receiving perineural saline reported a median score 10 times higher (more dysfunction) than those receiving ropivacaine (3 [0-24] vs 33 [0-44]; P = 0.035). In contrast, after infusion discontinuation, there were no statistically significant differences detected between treatment groups.Conclusions: After mastectomy, adding a multiple-day, ambulatory, continuous ropivacaine infusion to a single-injection ropivacaine paravertebral nerve block results in improved analgesia and less functional deficit during the infusion. However, no benefits were identified after infusion discontinuation. [ABSTRACT FROM AUTHOR]

We fail to understand how a single pain score at a single predetermined time point within the postanesthesia care unit (PACU) as proposed by Li and Xu could possibly provide more or improved information than including the entire recovery room analgesic experience with a median of all pain scores. While Li and Xu opine, 'because the pain score will likely decrease after opioid therapy, it is necessary to evaluate pain intensity at a predefined time point', we are unaware of any time point in the recovery room that has been deemed optimal for pain score assessment. 190 Reg Anesth Pain Med February 2021 Vol 46 No 2 PostScript Response to Li and Xu To the Editor We would like to thank Li and Xu for their letter regarding our recent publication. [Extracted from the article]

Background: Historically, the anterolateral interscalene block--deposition of local anesthetic adjacent to the brachial plexus roots/ trunks--has been used for surgical procedures involving the shoulder. The resulting block frequently failed to provide surgical anesthesia of the hand and forearm, even though the brachial plexus at this level included all of the axons of the upper-extremity terminal nerves. However, it remains unknown whether deposition of local anesthetic adjacent to the seventh cervical root or inferior trunk results in anesthesia of the hand and forearm. Methods: Using ultrasound guidance and a needle-in-plane posterior approach, a Tuohy needle was positioned with the tip located between the deepest and next-deepest visualized brachial plexus root/trunk, followed by injection of mepivacaine (1.5%). Grip strength and the tolerance to cutaneous electrical current in 5 terminal nerve distributions were measured at baseline and then every 5 minutes following injection for a total of 30 minutes. The primary end point was the proportion of cases in which the interscalene nerve block resulted in a decrease in grip strength of at least 90% and hand and forearm anesthesia (tolerance to >50 mA of current in all 5 terminal nerve distributions) within 30 minutes. The primary hypothesis was that a single-injection interscalene brachial plexus block produces a similar rate of anesthesia of the hand and forearm to the published success rate of 95% for other brachial plexus block approaches. Results: Of 55 subjects with blocks placed per protocol, all had a successful block of the shoulder as defined by inability to abduct at the shoulder joint. Thirty-three subjects had measurements at 30 minutes following local anesthetic deposition, and only 5 (15%) of these subjects had a surgical block of the hand and forearm (P < 0.0001; 95% confidence interval, 6%-33%). We therefore reject the hypothesis that the interscalene block as performed in this study provides equivalent anesthesia to the hand and forearm compared with other brachial plexus block techniques. Block failures of the hand and forearm were due to inadequate cutaneous anesthesia of the ulnar (n = 27; 82%), median (n = 26; 78%), or radial (n = 22; 67%) distributions; the medial forearm (n = 25; 76%); and/or the lateral forearm (n = 14; 42%). Failure to achieve at least a 90% reduction in grip strength occurred in 16 subjects (48%). Conclusions: This study did not find evidence to support the hypothesis that local anesthetic injected adjacent to the deepest brachial plexus roots/trunks reliably results in surgical anesthesia of the hand and forearm. [ABSTRACT FROM AUTHOR]

Abstract: Optimizing evidence-based medicine-and therefore the care of our patients-requires a public record of both the benefits and the risks of various medical interventions. Unfortunately, available evidence is often skewed because some clinical trials are withheld from publication; only selected data are reported, and statistical techniques are often inappropriately determined following data analysis. Prospective clinical trial registration (PCTR) is the public documentation of trial protocols-today primarily on the Internet-before data analysis (and ideally before trial commencement). The primary goals of PCTR are to reduce selective reporting and improve data analysis transparency, but it may also promote trial awareness for the public and other investigators. Prospective clinical trial registration is certainly not without problems, but many have been resolved, and the remainder is relatively minor in nature and easily overcome. Multiple organizations endorse (in some cases mandate) PCTR, including prominent committees of medical editors, the World Health Organization, the World Medical Association (responsible for the Helsinki Declaration), and, more recently, the US Food and Drug Administration. Although Regional Anesthesia and Pain Medicine does not currently require registration for published articles, PCTR in this and other anesthesiology and pain journals may become mandatory within the next few years. Potential authors/investigators will therefore benefit from becoming familiar with PCTR before mandatory registration implementation, and familiarity among readers may improve interpretation and understanding of clinical research results. [ABSTRACT FROM AUTHOR]

Background: When using ultrasound guidance to place a perineural catheter for a continuous peripheral nerve block, keeping the needle in plane and nerve in short axis results in a perpendicular needle-to-nerve orientation. Many have opined that when placing a perineural catheter via the needle, the acute angle may result in the catheter bypassing the target nerve when advanced beyond the needle tip. Theoretically, greater catheter tip-to-nerve distances result in less local anesthetic-to-nerve contact during the subsequent perineural infusion, leading to inferior analgesia. Although a potential solution may appear obvious-advancing the catheter tip only to the tip of the needle, leaving the catheter tip at the target nerve-this technique has not been prospectively evaluated. We therefore hypothesized that during needle in-plane ultrasound-guided perineural catheter placement, inserting the catheter a minimum distance (0-1 cm) past the needle tip is associated with improved postoperative analgesia compared with inserting the catheter a more traditional 5 to 6 cm past the needle tip.Methods: Preoperatively, subjects received a popliteal-sciatic perineural catheter for foot or ankle surgery using ultrasound guidance exclusively. Subjects were randomly assigned to have a single-orifice, flexible catheter inserted either 0 to 1 cm (n = 50) or 5 to 6 cm (n = 50) past the needle tip. All subjects received a single-injection mepivacaine (40 mL of 1.5% with epinephrine) nerve block via the needle, followed by catheter insertion and a ropivacaine 0.2% infusion (basal 6 mL/hr, bolus 4 mL, 30-min lockout), through at least the day after surgery. The primary end point was the average surgical pain as measured with a 0- to 10-point numeric rating scale the day after surgery. Secondary end points included time for catheter insertion, incidence of catheter dislodgement, maximum ("worst") pain scores, opioid requirements, fluid leakage at the catheter site, and the subjective degree of an insensate extremity.Results: Average pain scores the day after surgery for subjects of the 0- to 1-cm group were a median of 2.5 (interquartile range, 0.0-5.0), compared with 2.0 (interquartile range, 0.0-4.0) for subjects of the 5- to 6-cm group (P = 0.42). Similarly, among the secondary end points, no statistically significant differences were found between the 2 treatment groups. There was a trend of more catheter dislodgements in the minimum-insertion group (5 vs 1; P = 0.20).Conclusions: This study did not find evidence to support the hypothesis that, for popliteal-sciatic perineural catheters placed using ultrasound guidance and a needle-in-plane technique, inserting the catheter a minimum distance (0-1 cm) past the needle tip improves (or worsens) postoperative analgesia compared with inserting the catheter a more traditional distance (5-6 cm). Caution is warranted if extrapolating these results to other catheter designs, ultrasound approaches, or anatomic insertion sites. [ABSTRACT FROM AUTHOR]

Background: Previously, we have demonstrated that extending a continuous femoral nerve block (cFNB) from overnight to 4 days after total knee arthroplasty (TKA) provides clear benefits during the infusion, but not subsequent to catheter removal. However, there were major limitations in generalizing the results of that investigation, and we subsequently performed a very similar study using a multicenter format, with many health care providers, in patients on general orthopedic wards, thus greatly improving inference of the results to the general population. Not surprisingly, the perioperative/short-term outcomes differed greatly from the first, more limited study. We now present a prospective follow-up study of the previously published, multicenter, randomized controlled clinical trial to investigate the possibility that an extended ambulatory cFNB decreases long-term pain, stiffness, and functional disability after TKA, which greatly improves inference of the results to the general population.Methods: Subjects undergoing TKA received a cFNB with ropivacaine 0.2% from surgery until the following morning, at which time patients were randomized to continue either perineural ropivacaine (n=28) or normal saline (n=26). Patients were discharged with their catheter and a portable infusion pump, and catheters were removed on postoperative day 4. Health-related quality of life was measured using the Western Ontario and McMaster Universities Osteoarthritis Index preoperatively and then at 7 days, as well as 1, 2, 3, 6, and 12 months after surgery. This index evaluates pain, stiffness, and physical functional disability. For inclusion in the analysis, we required a minimum of 4 of the 6 time points, including day 7 and at least 2 of months 3, 6, and 12.Results: The 2 treatment groups had similar Western Ontario and McMaster Universities Osteoarthritis scores for the mean area-under-the-curve calculations (point estimate for the difference in mean area under the curve for the 2 groups [overnight infusion group - extended infusion group]=3.8; 95% confidence interval, -3.8 to +11.3; P=0.32) and at all individual time points (P>0.05).Conclusions: This investigation found no evidence that extending an overnight cFNB to 4 days improves (or worsens) subsequent pain, stiffness, or physical function after TKA in patients of multiple centers convalescing on general orthopedic wards. [ABSTRACT FROM AUTHOR]

Background: Although the efficacy of single-injection supraclavicular nerve blocks is well established, no controlled study of continuous supraclavicular blocks is available, and their relative risks and benefits remain unknown. In contrast, the analgesia provided by continuous infraclavicular nerve blocks has been validated in randomized controlled trials. We therefore compared supraclavicular with infraclavicular perineural local anesthetic infusion following distal upper-extremity surgery. Methods: Preoperatively, subjects were randomly assigned to receive a brachial plexus perineural catheter in either the infraclavicular or supraclavicular location using an ultrasound-guided nonstimulating catheter technique. Postoperatively, subjects were discharged home with a portable pump (400-mL reservoir) infusing 0.2% ropivacaine (basal rate of 8 mL/hr; 4-mL bolus dose; 30-min lockout interval). Subjects were followed up by telephone on an outpatient basis. The primary outcome was the average pain score on the day after surgery. Results: Sixty subjects were enrolled, with 31 and 29 randomized to receive an infraclavicular and supraclavicular catheter, respectively. All perineural catheters were successfully placed per protocol. Because of protocol violations and missing data, an intention-to-treat analysis was not used; rather, only subjects with catheters in situ and whom we were able to contact were included in the analyses. The day after surgery, subjects in the infraclavicular group reported average pain as median of 2.0 (10th-90th percentiles, 0.5-6.0) compared with 4.0 (10th-90th percentiles, 0.6-7.7) in the supraclavicular group (P = 0.025). Similarly, least pain scores (numeric rating scale) on postoperative day 1 were lower in the infraclavicular group compared with the supraclavicular group (0.5 [10th-90th percentiles, 0.0-3.5] vs 2.0 [10th-90th percentiles, 0.0-4.7], respectively; P = 0.040). Subjects in the infraclavicular group required less rescue oral analgesic (oxycodone, in milligrams) for breakthrough pain in the 18 to 24 hrs after surgery compared with the supraclavicular group (0.0 [10th-90th percentiles, 0.0-5.0] vs 5.0 [10th-90th percentiles, 0.0-15.0], respectively; P = 0.048). There were no statistically significant differences in other secondary outcomes. Conclusions: A local anesthetic infusion via an infraclavicular perineural catheter provides superior analgesia compared with a supraclavicular perineural catheter. [Copyright &y& Elsevier]

The authors present insights on the strengths and weaknesses of major ultrasound-guided catheter insertion approaches. It notes that easier identification and differentiation from surrounding structures can be achieved through the needle in-plane, nerve in short-axis approach. Using the same technique for both single-injection and perineural catheter placement is one of its benefits. It describes the needle out-of plane, nerve in short-axis approach where the catheter may remain nearer the nerve even when threaded more than a centimeter past the tip.

Background: Sciatic perineural catheters via a popliteal fossa approach and subsequent local anesthetic infusion provide potent analgesia and other benefits after foot and ankle surgery. Electrical stimulation (ES) and, more recently, ultrasound (US)-guided placement techniques have been described. However, because these techniques have not been compared in a randomized fashion, the optimal method remains undetermined. Therefore, we tested the hypotheses that popliteal-sciatic perineural catheters placed via US guidance require less time for placement and produce equivalent results, as compared with catheters placed using ES. Methods: Preoperatively, subjects receiving a popliteal-sciatic perineural catheter for foot and/or ankle surgery were randomly assigned to either the ES with a stimulating catheter or US-guided technique with a nonstimulating catheter. The primary end point was catheter insertion duration (in minutes) starting when the US transducer (US group) or catheter-placement needle (ES group) first touched the patient and ending when the catheter-placement needle was removed after catheter insertion. Results: All US-guided catheters were placed per protocol (n = 20), whereas only 80% of stimulation-guided catheters could be placed per protocol (n = 20, P = 0.106). All catheters placed per protocol in both groups resulted in a successful surgical block. Perineural catheters placed by US took a median (10th-90th percentile) of 5.0 min (3.9-11.1 min) compared with 10.0 min (2.0-15.0 min) for stimulation (P = 0.034). Subjects in the US group experienced less pain during catheter placement, scoring discomfort a median of 0 (0.0-2.1) compared with 2.0 (0.0-5.0) for the stimulation group (P = 0.005) on a numeric rating scale of 0 to 10. Conclusions: Placement of popliteal-sciatic perineural catheters takes less time and produces less procedure-related discomfort when using US guidance compared with ES. [ABSTRACT FROM AUTHOR]

Abstract: Brachial plexus blockade is the cornerstone of the peripheral nerve regional anesthesia practice of most anesthesiologists. As part of the American Society of Regional Anesthesia and Pain Medicine''s commitment to providing intensive evidence-based education related to regional anesthesia and analgesia, this article is a complete update of our 2002 comprehensive review of upper extremity anesthesia. The text of the review focuses on (1) pertinent anatomy, (2) approaches to the brachial plexus and techniques that optimize block quality, (4) local anesthetic and adjuvant pharmacology, (5) complications, (6) perioperative issues, and (6) challenges for future research. [Copyright &y& Elsevier]

Background and Objectives: The posterior approach to the brachial plexus-or cervical paravertebral block-has advantages over the anterolateral interscalene approach, but concerns regarding “blind” needle placement near the neuraxis have limited the acceptance of this useful technique. We present a technique to place an interscalene perineural catheter that potentially decreases neuraxial involvement with the use of ultrasound guidance. Methods: A 55-year-old man scheduled for total shoulder arthroplasty underwent placement of an interscalene perineural catheter. The posterior approach was selected to avoid the external jugular vein and anticipated sterile surgical field. Under in-plane ultrasound guidance, a 17-gauge insulated Tuohy-tip needle was inserted between the levator scapulae and trapezius muscles, and guided through the middle scalene muscle, remaining less than 2 cm below the skin throughout. Deltoid and biceps contractions were elicited at a current of 0.6 mA, and a 19-gauge stimulating catheter was advanced 5 cm beyond the needle tip, without a concomitant decrease in motor response. Results: The initial 40 mL 0.5% ropivacaine bolus via the catheter resulted in unilateral anesthesia typical of an interscalene block; and subsequent perineural infusion of 0.2% ropivacaine was delivered via portable infusion pump through postoperative day 4. Conclusions: Continuous interscalene block using an ultrasound-guided posterior approach is an alternative technique that retains the benefits of posterior catheter insertion, but potentially reduces the risk of complications that may result from blind needle insertion. [Copyright &y& Elsevier]

Background and Objectives: It is currently unknown if the primary determinant of continuous peripheral nerve block effects is simply total drug dose, or whether local anesthetic concentration and/or volume have an influence. We therefore tested the null hypothesis that providing ropivacaine at different concentrations and rates — but at an equal total basal dose — produces similar effects when used in a continuous interscalene nerve block. Methods: Preoperatively, an anterolateral interscalene perineural catheter was inserted using the anterolateral approach in patients undergoing moderately painful shoulder surgery. Subjects were randomly assigned to receive a postoperative perineural infusion of either 0.2% ropivacaine (basal 8 mL/h, bolus 4 mL) or 0.4% ropivacaine (basal 4 mL/h, bolus 2 mL) through the second postoperative day. Our primary endpoint was the incidence of an insensate hand/finger during the 24 hours beginning the morning following surgery. Results: The incidence of an insensate hand/finger did not differ between the treatment groups (n = 50) to a statistically significant degree (0.2% ropivacaine, mean [SD] of 0.8 [1.3] times; 0.4% ropivacaine, mean 0.3 [0.6] times; estimated difference = 0.5 episodes, 95% confidence interval, −0.1 to 1.1 episodes; P = .080). However, this is statistically inconclusive given the confidence interval. In contrast, pain (P = .020) and dissatisfaction (P = .011) were greater in patients given 0.4% ropivacaine. Conclusions: For continuous interscalene nerve blocks, given the statistically inconclusive primary endpoint results and design limitations of the current study, further research on this topic is warranted. In contrast, providing a lower concentration of local anesthetic at a higher basal rate provided superior analgesia. [Copyright &y& Elsevier]

Background and Objectives: After total knee arthroplasty (TKA), hospitalization may be shortened by allowing patients to return home with a continuous femoral nerve block (CFNB). This study quantified the hospitalization costs for 10 TKA patients receiving ambulatory CFNB versus a matched cohort of 10 patients who received CFNB only during hospitalization. Methods: We examined the medical records (n = 125) of patients who underwent a unilateral, primary, tricompartment TKA with a postoperative CFNB by 1 surgeon at one institution in an 18-month period beginning January 2004. Each of the 10 patients discharged home with an ambulatory CFNB (cases) was matched with a patient with a hospital-only CFNB (controls) for age, gender, body mass index, and health status. Financial data were extracted from the hospital microcosting database. Results: Nine patients with ambulatory CFNB (cases) were discharged home on postoperative day (POD) 1 and 1 on POD 4. Of the controls, 3 were discharged home on POD 3, 6 on POD 4, and 1 on POD 5. The median (range) costs of hospitalization (excluding implant and professional fees) was $5,292 ($4,326-$7,929) for ambulatory cases compared with $7,974 ($6,931-$9,979) for inpatient controls (difference = $2,682, 34% decrease, P < .001). The total charges for hospitalization, the implant, and professional fees was $33,646 ($31,816-$38,468) for cases compared with $39,100 ($36,096-$44,098) for controls (difference = $5,454, 14% decrease, P < .001). Conclusions: This study provides evidence that ambulatory CFNB for selected patients undergoing TKA has the potential to reduce hospital length of stay and associated costs and charges. However, the current study has significant inherent limitations based on the study design. Additional research is required to replicate these results in a prospective, randomized, controlled trial and to determine whether any savings exceed additional CFNB costs such as from complications, having caregivers provide care at home, and additional hospital/health care provider visits. [Copyright &y& Elsevier]

Objective: Total elbow arthroplasty (TEA) often results in severe postoperative pain requiring hospitalization to provide potent analgesia. This prospective series investigated the feasibility of converting TEA into an ambulatory procedure using a continuous infraclavicular nerve block provided at home with a portable infusion pump.Case Report: Preoperatively, patients undergoing TEA had an infraclavicular perineural catheter and peripheral nerve block placed. Postoperatively, perineural ropivacaine was delivered through postoperative day (POD) 3 to 6. Patients were discharged home when they met specific, prospectively defined criteria as early as POD 1 for the first phase and directly from the recovery room for the second phase. Of the 2 patients in the first phase who remained hospitalized for at least 1 postoperative night, both met discharge criteria in the recovery room, required no medical interventions during their admission, and were discharged home the following morning. The patient of phase 2 met discharge criteria in the recovery room and was discharged home at that time. Postoperative pain was well controlled, opioid requirements and sleep disturbances were minimal, and patient satisfaction was high for all patients.Conclusions: These cases suggest that for a subset of patients without major comorbidities, it is feasible to convert total elbow arthroplasty into an ambulatory procedure using a continuous infraclavicular nerve block as part of a multimodal analgesic regimen provided at home. Additional research is required to replicate these results in a controlled trial, define the appropriate subset of patients, and assess the incidence of complications associated with this practice before its mainstream use. [ABSTRACT FROM AUTHOR]

Objective: Total hip arthroplasty (THA) results in severe postoperative pain requiring hospitalization to provide potent analgesia. Consequently, the average duration of hospitalization after THA in the United States is 4 to 5 days. This prospective study investigated the feasibility of converting THA into an overnight-stay procedure using a continuous psoas compartment nerve block provided at home with a portable infusion pump. Case Report: Preoperatively, patients undergoing THA had a psoas compartment perineural catheter placed. Postoperatively, perineural ropivacaine 0.2% was delivered through postoperative day (POD) 4. Patients were discharged home when they met specific, prospectively defined criteria, as early as POD 3 for the first phase and POD 1 for the second phase. Of the patients in the first phase (n = 7) who remained hospitalized for at least 3 postoperative nights, 5 met discharge criteria on POD 1 and the remainder on POD 2. Of the patients in phase 2 (n = 5), all but 1 met discharge criteria on POD 1 and 3 were discharged directly home on POD 1. Postoperative pain was well controlled, opioid requirements and sleep disturbances were minimal, and patient satisfaction high. Conclusions: These results suggest that for a subset of patients without major comorbidities, it is feasible to convert THA into an overnight-stay procedure using an ambulatory continuous psoas compartment nerve block as part of a multimodal analgesic regimen provided at home. Additional research is required to replicate these results in a controlled trial, define the appropriate subset of patients, and assess the incidence of complications associated with this practice before its mainstream use. [Copyright &y& Elsevier]

Background and Objectives: Although a continuous interscalene nerve block (CISB) has been shown to provide potent analgesia after major shoulder surgery, its potential effects on postoperative rehabilitation remain uninvestigated. Therefore, this retrospective case-control study was undertaken to determine the association between CISB and joint range-of-motion after total shoulder arthroplasty (TSA).Methods: The medical records for patients who underwent TSA at our institution in the previous 3 years were examined. Each patient with a CISB (cases) was matched with a patient without a CISB (controls) for the following variables: age, gender, and TSA type (primary v revision). Data collected included maximum shoulder elevation and external rotation (primary endpoints), along with pre- and postoperative pain scores.Results: Of 134 charts reviewed, 25 cases were matched with an equal number of controls. On postoperative day 1, patients with or without a CISB achieved a median (5th-95th percentiles) of 85% (51-100) and 33% (11-56) of their surgeon-defined goal for elevation (P = .048), respectively, and attained 100% (33-100) and 17% (-81-68) for external rotation (P < .001), respectively. The median numeric rating pain score (NRS) during shoulder movement for patients with CISB was 2.0 (0.0-8.7) versus 8.5 (1.8-10.0) for patients without CISB (P < .001). Least, median, and highest resting NRS for the 24 hours after surgery were 0.0 (0.0-5.8), 1.0 (0.0-6.4), and 3.0 (0.0-9.0) for patients with CISB, respectively, versus 2.0 (0.0-7.7), 6.0 (0.3-9.6), and 8.0 (0.0-10.0) for patients without CISB (P = .030, P < .001, and P < .001 between groups, respectively).Conclusions: The day after TSA, a CISB is associated with increased shoulder range of motion, most likely resulting from the potent analgesia these nerve blocks provide. [ABSTRACT FROM AUTHOR]

Objectives: Despite the tremendous growth of peripheral nerve blocks, no standard format exists to document their performance. Our objective was to create a peripheral nerve block form based on key elements of literature evidence and on our own group consensus.Results: We describe the process and results of our multi-institutional effort to construct a standardized peripheral nerve block procedure form.Conclusion: A form was developed to help meet the medical, legal, and billing requirements of documentation consistent with the performance of peripheral nerve block. [ABSTRACT FROM AUTHOR]

Basal infusion versus intermittent boluses for perineural catheters: should we take the "continuous" out of "continuous peripheral nerve blocks"? However, more-recent advances in pump technology have enabled automated intermittent boluses without the need for active patient involvement - the pumps may be programmed to repeatedly deliver a bolus volume.[3] Within the epidural space, automated repeated boluses improve analgesia compared with a basal infusion of an equivalent local anesthetic volume/dose,[3] possibly due to a more uniform local anesthetic spread.[6] Continuous adductor canal blocks: Does varying local anesthetic delivery method (automatic repeated bolus doses versus continuous basal infusion) influence cutaneous analgesia and quadriceps femoris strength? Continuous transversus abdominis plane nerve blocks: Does varying local anesthetic delivery method-automatic repeated bolus versus continuous basal infusion-influence the extent of sensation to cold?. [Extracted from the article]

A letter is presented about a prospective series of patients who were treated with three-day ambulatory perineural local anesthetic infusion in addition to the customary single-injection brachial plexus block for shoulder manipulation. An electronic portable infusion pump was used to administer the infusions at home. The ambulatory continuous interscalene nerve block improved both short- and long-term outcomes following shoulder manipulation for refractory adhesive capsulitis.

The author attempts to help readers answer the question of what readers will do with the data of a meta-analysis compiling the findings of multiple smaller investigations. The author believes great caution is needed when interpreting effect sizes produced by meta-analysis. The author claims that although potential biases exist in meta-analyses, properly performed meta-analyses attempt to highlight these biases and should explore the reasons for identified heterogeneity.

An introduction to the journal is presented in which the authors discuss the results of the examination conducted by E. Yilmaz-Rastoder, M. S. Gold, K. A. Hough and colleagues on the several agents on the compound action potential (CAP) of an isolated rat sciatic nerve.

Background and Objectives: Transversus abdominis plane (TAP) blocks anesthetize the lower abdominal wall, and TAP catheters have been used to provide prolonged postoperative analgesia after laparotomy. The use of TAP catheters on an outpatient basis has not yet been described. We present our experience with ultrasound-guided TAP perineural catheter insertion and subsequent management of ambulatory TAP local anesthetic infusions after inguinal hernia repair. Methods: Three patients scheduled for unilateral open inguinal hernia repair underwent preoperative posterior TAP catheter placement for postoperative pain management using a technique employing ultrasound guidance alone. A bolus of local anesthetic solution was injected via the catheter in divided doses, and block onset was confirmed before surgery. Postoperatively, a continuous infusion of ropivacaine 0.2% was delivered using a portable infusion pump, and patients were discharged with a prescription for oral analgesics for breakthrough pain and perineural infusion instructions. Patients were followed up daily by telephone. Results: All patients underwent successful TAP catheter insertion and maintained their catheters until postoperative day 2. All patients reported minimal pain for the duration of infusion without the need for any supplemental opioid analgesics, high satisfaction with postoperative analgesia, and no infusion-related complications. Conclusions: An ultrasound-guided TAP catheter and ambulatory local anesthetic perineural infusion are a promising option for prolonged postoperative analgesia after outpatient inguinal hernia repair. A posterior insertion permits preoperative placement by keeping the catheter away from the planned surgical field. [ABSTRACT FROM AUTHOR]