Search

BACKGROUND:A continuous adductor canal block provides analgesia after surgical procedures of the knee. Recent neuroanatomic descriptions of the thigh and knee led us to speculate that local anesthetic deposited in the distal thigh close to the adductor hiatus would provide superior analgesia compared to a more proximal catheter location. We therefore tested the hypothesis that during a continuous adductor canal nerve block, postoperative analgesia would be improved by placing the perineural catheter tip 2-3 cm cephalad to where the femoral artery descends posteriorly to the adductor hiatus (distal location) compared to a more proximal location at the midpoint between the anterior superior iliac spine and the superior border of the patella (proximal location). METHODS:Preoperatively, subjects undergoing total knee arthroplasty received an ultrasound-guided perineural catheter inserted either in the proximal or distal location within the adductor canal in a randomized, subject-masked fashion. Subjects received a single injection of lidocaine 2% via the catheter preoperatively, followed by an infusion of ropivacaine 0.2% (8 mL/h basal, 4 mL bolus, 30 minutes lockout) for the study duration. After joint closure, the surgeon infiltrated the entire joint using 30 mL of ropivacaine (0.5%), ketorolac (30 mg), epinephrine (5 μg/mL), and tranexamic acid (2 g). The primary end point was the median level of pain as measured on a numeric rating scale (NRS) during the time period of 8:00 AM to 12:00 PM the day after surgery. RESULTS:For the primary end point, the NRS of subjects with a catheter inserted at the proximal location (n = 24) was a median (10th, 25th-75th, 90th quartiles) of 0.5 (0.0, 0.0-3.2, 5.0) vs 3.0 (0.0, 2.0-5.4, 7.8) for subjects with a catheter inserted in the distal location (n = 26; P = .011). Median and maximum NRSs were lower in the proximal group at all other time points, but these differences did not reach statistical significance. There were no clinically relevant or statistically significant differences between the treatment groups for any other secondary end point, including opioid consumption and ambulation distance. CONCLUSIONS:For continuous adductor canal blocks accompanied by intraoperative periarticular local anesthetic infiltration, analgesia the day after knee arthroplasty is improved with a catheter inserted at the level of the midpoint between the anterior superior iliac spine and the superior border of the patella compared with a more distal insertion closer to the adductor hiatus.

BACKGROUND:Regional anesthesia is of benefit for outpatient surgery given its demonstrated improvement in analgesia and decrease in complications, resulting in shorter average recovery room times and lower hospital readmission rates. Unfortunately, there are few epidemiological studies outlining the overall utilization of peripheral nerve blocks (PNBs) in this setting. Therefore, the primary objective of this study was to report the overall utilization of several types of PNBs among all candidate cases in the outpatient setting within the United States. METHODS:We identified all cases from the National Anesthesia Clinical Outcomes Registry that were performed as an outpatient surgery. We reported the frequency of various types of PNBs among all candidate cases, defined as cases that potentially could have received a PNB. Changes in prevalence of PNB utilization from 2010 to 2015 were analyzed by using logistic regression. RESULTS:Of the 12,911,056 outpatient surgeries in the National Anesthesia Clinical Outcomes Registry, 3,297,372 (25.5%) were amenable to a PNB. However, the overall PNB frequency was only 3.3% of the possible cases. The overall utilization for PNB of the brachial plexus, sciatic nerve, and femoral nerve were 6.1%, 1.5%, and 1.9%, respectively. The surgical procedures generating the highest volume of PNBs were shoulder arthroscopies and anterior cruciate ligament reconstruction, in which 41% and 32% received a PNB, respectively. During this time period, there was a significant increase in overall PNB utilization for both single-injection and continuous PNB (P < .0001). However, the proportion of continuous PNB to single-injection PNB did not increase significantly. CONCLUSIONS:While the overall frequency of PNB is relatively low, there was a significant increase in its prevalence during the study period. Regional anesthesia offers significant positive impact for perioperative outcomes and hospital efficiency metrics; however, it is not clear what is limiting its widespread use. Future studies are necessary to identify barriers and disparities in care to implement methods to increase regional anesthesia volume nationwide where beneficial and appropriate.

BACKGROUND:Based on the assumption that relatively large volumes of local anesthetic optimize an adductor canal block (ACB), we theorized that an ACB administered as repeated boluses would improve analgesia without compromising mobility, compared with a continuous infusion. METHODS:We performed a randomized, blinded, controlled study, including patients scheduled for total knee arthroplasty with spinal anesthesia. Patients received 0.2% ropivacaine via a catheter in the adductor canal administered as either repeated intermittent boluses (21 mL/3 h) or continuous infusion (7 mL/h). The primary outcome was total (postoperative day [POD], 0-2) opioid consumption (mg), administered as patient-controlled analgesia. Pain, ambulation, and quadriceps muscle strength were secondary outcomes. RESULTS:We randomized 110 patients, of whom 107 were analyzed. Total opioid consumption (POD, 0-2) was a median (range) of 23 mg (0-139) in the bolus group and 26 mg (3-120) in the infusion group (estimated median difference, 4 mg; 95% confidence interval [CI], -13 to 5; P = .29). Linear mixed-model analyses revealed no difference in pain during knee flexion (mean difference, 2.6 mm; 95% CI, -2.9 to 8.0) or at rest (mean difference, 1.7 mm; 95% CI, -1.5 to 4.9). Patients in the bolus group had improved quadriceps sparing on POD 2 (median difference, 7.4%; 95% CI, 0.5%-15.5%). However, this difference was not present on POD 1 or reflected in the ambulation tests (P > .05). CONCLUSIONS:Changing the mode of administration for an ACB from continuous infusion to repeated intermittent boluses did not decrease opioid consumption, pain, nor mobility.

Percutaneous peripheral nerve stimulation (PNS) is an FDA-cleared pain treatment. Occasionally, fragments of the lead (MicroLead, SPR Therapeutics, LLC, Cleveland, OH, USA) may be retained following lead removal. Since the lead is metallic, there are associated magnetic resonance imaging (MRI) risks. Therefore, the objective of this investigation was to evaluate MRI-related issues (i.e., magnetic field interactions, heating, and artifacts) for various lead fragments.Testing was conducted using standardized techniques on lead fragments of different lengths (i.e., 50, 75, and 100% of maximum possible fragment length of 12.7 cm) to determine MRI-related problems. Magnetic field interactions (i.e., translational attraction and torque) and artifacts were tested for the longest lead fragment at 3 Tesla. MRI-related heating was evaluated at 1.5 Tesla/64 MHz and 3 Tesla/128 MHz with each lead fragment placed in a gelled-saline filled phantom. Temperatures were recorded on the lead fragments while using relatively high RF power levels. Artifacts were evaluated using T1-weighted, spin echo, and gradient echo (GRE) pulse sequences.The longest lead fragment produced only minor magnetic field interactions. For the lead fragments evaluated, physiologically inconsequential MRI-related heating occurred at 1.5 Tesla/64 MHz while under certain 3 Tesla/128 MHz conditions, excessive temperature elevations may occur. Artifacts extended approximately 7 mm from the lead fragment on the GRE pulse sequence, suggesting that anatomy located at a position greater than this distance may be visualized on MRI.MRI may be performed safely in patients with retained lead fragments at 1.5 Tesla using the specific conditions of this study (i.e., MR Conditional). Due to possible excessive temperature rises at 3 Tesla, performing MRI at that field strength is currently inadvisable.

BackgroundPeripheral nerve stimulation has been used for decades to treat chronic pain but has not been used for postoperative analgesia due to multiple limitations, beginning with invasive electrode placement. With the development of small-diameter/gauge leads enabling percutaneous insertion, ultrasound guidance for accurate introduction, and stimulators small enough to be adhered to the skin, neurostimulation may now be provided in a similar manner to continuous peripheral nerve blocks. Here, we report on the use of ultrasound-guided percutaneous peripheral nerve stimulation to treat postoperative pain.Materials and methodsSubjects within 60 days of a total knee arthroplasty with pain insufficiently treated with oral analgesics had a 0.2-mm-diameter electrical lead (pre-loaded into a 20 gauge needle) introduced percutaneously using ultrasound guidance with the tip located approximately 0.5-1.0 cm from the femoral nerve (a second lead was inserted approximately 1.0-3.0 cm from the sciatic nerve for posterior knee pain). An external stimulator delivered current. Endpoints were assessed before and after lead insertion and the leads subsequently removed. Due to the small sample size for this pilot/feasibility study, no statistics were applied to the data.ResultsLeads were inserted in subjects (n = 5) 8-58 days postoperatively. Percutaneous peripheral nerve stimulation decreased pain an average of 93% at rest (from a mean of 5.0 to 0.2 on a 0-10 numeric rating scale), with 4 of 5 subjects experiencing complete resolution of pain. During passive and active knee motion pain decreased an average of 27 and 30%, respectively. Neither maximum passive nor active knee range-of-motion was consistently affected.ConclusionsUltrasound-guided percutaneous peripheral nerve stimulation may be a practical modality for the treatment of postoperative pain following orthopedic surgical procedures, and further investigation appears warranted.

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.

Cryoneurolysis entails using low temperatures to reversibly ablate nerves, with a subsequent analgesia duration measured in weeks or months. Previously, clinical applications for acute pain were limited because treatment originally required exposing the target nerve surgically. However, three developments have now made it possible to provide prolonged postoperative analgesia by cryoneurolysis: 1) new portable, hand-held cryoneurolysis devices, 2) ultrasound machine proliferation, and, 3) anesthesiologists trained in ultrasound-guided peripheral nerve block administration. This report is the first to describe the use of a single preoperative administration of ultrasound-guided percutaneous cryoneurolysis to provide multiple weeks of analgesia following shoulder rotator cuff repair and total knee arthroplasty. Considering the significant benefits of cryoanalgesia relative to continuous peripheral nerve blocks (e.g., lack of catheter/pump care, extremely long duration), this analgesic modality may be a practical alternative for the treatment of prolonged post-surgical pain in a select group of surgical patients.

We present the case of a 38-year-old man undergoing surgical repair of his pectoralis major tendon. An interscalene catheter was placed between the middle and lower trunks of the brachial plexus. Postoperatively, ropivacaine 0.2% was infused through postoperative day 3. The patient had excellent pain control requiring minimal opioid analgesics. A catheter between the middle and lower trunks of the brachial plexus provided excellent postoperative analgesia after pectoralis major tendon reinsertion. Additionally, the block likely protected the surgical repair during emergence from anesthesia and in the early postoperative period by providing a motor block of the pectoralis major muscle.

We report 3 different cases in which ultrasound-guided percutaneous cryoneurolysis was performed to treat acute pain: 1 patient with refractory incisional pain after percutaneous nephrolithotomy; 1 patient with burns to the foot; and 1 patient with pain from iliac crest grafting. Acute pain associated with surgery or injury is a challenge to treat with local anesthetic-based regional anesthesia techniques when the anticipated pain duration exceeds a few days. Cryoneurolysis is an alternative analgesic method that utilizes extremely cold temperatures to reversibly ablate peripheral nerves and is potentially a novel method for acute pain management.

While neurostimulation-stimulation of the nervous system using electrical current-has been used to treat chronic pain, its use treating postsurgical pain has been limited. Here, we report on the clinical application of a novel investigational lead to provide analgesia following total knee arthroplasty. In 5 subjects, leads were inserted percutaneously using ultrasound guidance within 0.5 to 3.0 cm of the femoral and/or sciatic nerve(s). With the delivery of current, pain decreased an average of 63% at rest, with 4 of 5 subjects having relief of > 50%. During passive and active knee flexion, pain decreased an average of 14% and 50%, with 0/3 and 1/2 subjects attaining > 50% relief, respectively. Ultrasound-guided percutaneous peripheral nerve stimulation may be a practical modality for the treatment of postsurgical pain.

ObjectiveTo review the published evidence regarding perioperative analgesic techniques for breast cancer-related surgery.DesignTopical review.MethodsRandomized, controlled trials (RCTs) were selected for inclusion in the review. Also included were large prospective series providing estimates of potential risks and technical reports and small case series demonstrating a new technique or approaches of interest to clinicians.ResultsA total of 514 abstracts were reviewed, with 284 studies meeting criteria for full review. The evidence regarding preemptive ketamine, scheduled opioids, perioperative non-steroidal anti-inflammatory drugs (NSAIDs), and intravenous lidocaine is mixed and deserves further investigation. There is strong evidence that both pregabalin and gabapentin provide analgesic benefits following breast surgery. There is minimal and conflicting data from high-quality randomized, controlled studies suggesting that directly infiltrating and/or infusing local anesthetic (liposome encapsulated or unencapsulated) into the surgical wound is a reliably effective analgesic. In contrast, there is a plethora of data demonstrating the potent analgesia, opioid sparing, and decreased opioid-related side effects from thoracic epidural infusion and both single-injection and continuous paravertebral nerve blocks (the latter two demonstrating decreased persistent post-surgical pain between 2.5 and 12 months). Techniques with limited-yet promising-data deserving additional investigation include brachial plexus blocks, cervical epidural infusion, interfascial plane blocks, and interpleural blocks.ConclusionsWhile there are currently multiple promising analgesic techniques for surgical procedures of the breast that deserve further study, the only modalities demonstrated to provide potent, consistent perioperative pain control are thoracic epidural infusion and paravertebral nerve blocks.

BackgroundPercutaneous neurostimulation of the peripheral nervous system involves the insertion of a wire "lead" through an introducing needle to target a nerve/plexus or a motor point within a muscle. Electrical current may then be passed from an external generator through the skin via the lead for various therapeutic goals, including providing analgesia. With extended use of percutaneous leads sometimes greater than a month, infection is a concern. It was hypothesized that the infection rate of leads with a coiled design is lower than for leads with a noncoiled cylindrical design.MethodsThe literature was retrospectively reviewed for clinical studies of percutaneous neurostimulation of the peripheral nervous system of greater than 2 days that included explicit information on adverse events. The primary endpoint was the number of infections per 1,000 indwelling days.ResultsForty-three studies were identified that met inclusion criteria involving coiled (n = 21) and noncoiled (n = 25) leads (3 studies involved both). The risk of infection with noncoiled leads was estimated to be 25 times greater than with coiled leads (95% confidence interval [CI] 2 to 407, P = 0.006). The infection rates were estimated to be 0.03 (95% CI 0.01 to 0.13) infections per 1,000 indwelling days for coiled leads and 0.83 (95% CI 0.16 to 4.33) infections per 1,000 indwelling days for noncoiled leads (P = 0.006).ConclusionsPercutaneous leads used for neurostimulation of the peripheral nervous system have a much lower risk of infection with a coiled design compared with noncoiled leads: approximately 1 infection for every 30,000 vs. 1,200 indwelling days, respectively.

PurposeRetrospective studies have associated perioperative regional anesthesia/analgesia during mastectomy for breast cancer with a decreased incidence of cancer recurrence. However, to date, no prospective data from a randomized controlled trial have been reported. In a previous study we found that extending a single-injection paravertebral block with a multiple-day perineural local anesthetic infusion improves analgesia. This follow-up study investigates the rates of cancer recurrence for the single-injection and multiple-day infusion treatments.MethodsPatients undergoing unilateral (n = 24) or bilateral mastectomy (n = 36) were included in the study. All patients had been diagnosed with breast cancer or tumor in situ, except for six patients who were receiving prophylactic bilateral mastectomy and were excluded from analyses. Patients received unilateral or bilateral single-injection thoracic paravertebral block(s) corresponding to their surgical site(s) with ropivacaine and perineural catheter(s). Subsequently, patients were randomized to receive either ropivacaine 0.4% (n = 30) or normal saline (n = 30) via their catheter(s) until catheter removal on postoperative day 3. Cancer recurrence from the date of surgery until at least 2 years post surgery was investigated via chart review.ResultsFive of the 54 (9.2%) patients experienced a cancer recurrence following mastectomy-3 of 26 (11.5%) of the patients with perineural ropivacaine and 2 of 28 (7.1%) of the patients with perineural saline.ConclusionsThis pilot study found no evidence that extending a single-injection paravertebral block with a multi-day perineural local anesthetic infusion decreases the risk of post-mastectomy cancer recurrence. However, due to the small sample size of this investigation, further research is needed to draw definitive conclusions.

BackgroundIt remains unknown whether continuous or scheduled intermittent bolus local anesthetic administration is preferable for transversus abdominis plane (TAP) catheters. We therefore tested the hypothesis that when using TAP catheters, providing local anesthetic in repeated bolus doses increases the cephalad-caudad cutaneous effects compared with a basal-only infusion.MethodsBilateral TAP catheters (posterior approach) were inserted in 24 healthy volunteers followed by ropivacaine 2 mg/mL administration for a total of 6 hours. The right side was randomly assigned to either a basal infusion (8 mL/h) or bolus doses (24 mL administered every 3 hours for a total of 2 bolus doses) in a double-masked manner. The left side received the alternate treatment. The primary end point was the extent of sensory deficit as measured by cool roller along the axillary line at hour 6 (6 hours after the local anesthetic administration was initiated). Secondary end points included the extent of sensory deficit as measured by cool roller and Von Frey filaments along the axillary line and along a transverse line at the level of the anterior superior iliac spine at hours 0 to 6.ResultsAlthough there were statistically significant differences between treatments within the earlier part of the administration period, by hour 6 the difference in extent of sensory deficit to cold failed to reach statistical significance along the axillary line (mean = 0.9 cm; SD = 6.8; 95% confidence interval -2.0 to 3.8; P = .515) and transverse line (mean = 2.5 cm; SD = 10.1; 95% confidence interval -1.8 to 6.8; P = .244). Although the difference between treatments was statistically significant at various early time points for the horizontal, vertical, and estimated area measurements of both cold and mechanical pressure sensory deficits, no comparison remained statistically significant by hour 6.ConclusionsNo evidence was found in this study involving healthy volunteers to support the hypothesis that changing the local anesthetic administration technique (continuous basal versus hourly bolus) when using ropivacaine 0.2% and TAP catheters at 8 mL/h and 24 mL every 3 hours significantly influences the cutaneous effects after 6 hours of administration. Additional research is required to determine whether changing variables (eg, local anesthetic concentration, basal infusion rate, bolus dose volume, and/or interval) would provide different results.

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]

A continuous peripheral nerve block (CPNB) consists of a percutaneously inserted catheter with its tip adjacent to a target nerve/plexus through which local anesthetic may be administered, providing a prolonged block that may be titrated to the desired effect. In the decades after its first report in 1946, a plethora of data relating to CPNB was published, much of which was examined in a 2011 Anesthesia & Analgesia article. The current update is an evidence-based review of the CPNB literature published in the interim. Novel insertion sites include the adductor canal, interpectoral, quadratus lumborum, lesser palatine, ulnar, superficial, and deep peroneal nerves. Noteworthy new indications include providing analgesia after traumatic rib/femur fracture, manipulation for adhesive capsulitis, and treating abdominal wall pain during pregnancy. The preponderance of recently published evidence suggests benefits nearly exclusively in favor of catheter insertion using ultrasound guidance compared with electrical stimulation, although little new data are available to help guide practitioners regarding the specifics of ultrasound-guided catheter insertion (eg, optimal needle-nerve orientation). After some previous suggestions that automated, repeated bolus doses could provide benefits over a basal infusion, there is a dearth of supporting data published in the past few years. An increasing number of disposable infusion pumps does now allow a similar ability to adjust basal rates, bolus volume, and lockout times compared with their electronic, programmable counterparts, and a promising area of research is communicating with and controlling pumps remotely via the Internet. Large, prospective studies now document the relatively few major complications during ambulatory CPNB, although randomized, controlled studies demonstrating an actual shortening of hospitalization duration are few. Recent evidence suggests that, compared with femoral infusion, adductor canal catheters both induce less quadriceps femoris weakness and improve mobilization/ambulation, although the relative analgesia afforded by each remains in dispute. Newly published data demonstrate that the incidence and/or severity of chronic, persistent postsurgical pain may, at times, be decreased with a short-term postoperative CPNB. Few new CPNB-related complications have been identified, although large, prospective trials provide additional data regarding the incidence of adverse events. Lastly, a number of novel, alternative analgesic modalities are under development/investigation. Four such techniques are described and contrasted with CPNB, including single-injection peripheral nerve blocks with newer adjuvants, liposome bupivacaine used in wound infiltration and peripheral nerve blocks, cryoanalgesia with cryoneurolysis, and percutaneous peripheral nerve stimulation.

An online database search with subsequent article review was performed in order to review the various analgesic modalities for breast cancer surgery. Of 514 abstracts, 284 full-length manuscripts were reviewed. The effect of pharmacologic interventions is varied (NSAIDS, opioids, anticonvulsants, ketamine, lidocaine). Likewise, data from high-quality randomized, controlled studies on wound infiltration (including liposome encapsulated) and infusion of local anesthetic are minimal and conflicting. Conversely, abundant evidence demonstrates paravertebral blocks and thoracic epidural infusions provide effective analgesia and minimize opioid requirements, while decreasing opioid-related side effects in the immediate postoperative period. Other techniques with promising - but extremely limited - data include cervical epidural infusion, brachial plexus, interfascial plane and interpleural blocks. In conclusion, procedural interventions involving regional blocks are more conclusively effective than pharmacologic modalities in providing analgesia to patients following surgery for breast cancer.

ObjectivesThe addition of a perioperative continuous paravertebral nerve block (cPVB) to a single-injection thoracic paravertebral nerve block (tPVB) has demonstrated improved analgesia in breast surgery. However, its use following isolated post-mastectomy reconstruction using a latissimus dorsi flap (LDF) has not previously been examined.MethodsWe performed a retrospective review of patients who underwent salvage breast reconstruction with a unilateral LDF by a single surgeon. Preoperatively, all patients received a single-injection tPVB with 0.5% ropivacaine. Additionally, patients had the option for catheter placement to receive a continuous 0.2% ropivacaine infusion with intermittent boluses. Infusions commenced in the recovery room and the catheters were removed on the morning of discharge. The primary endpoint was the mean pain numeric rating scale (NRS) scores for the 24-hour period beginning at 7:00 on post-operative day 1.ResultsA total of 22 patients were included in this study (11-cPVB and 11-tPVB). The mean NRS pain score of cPVB patients (3.5 (standard deviation (SD) 1.8) was lower than that of the single-injection tPVB patients (4.4 (SD 2.1), however this difference was not statistically significant (P = 0.31). The length of hospital stay and opioid use was not statistically different between groups.ConclusionsPatients receiving a cPVB in addition to tPVB after LDF reconstruction experienced similar pain to those receiving tPVB alone. A larger, randomized clinical trial is warranted to fully determine the benefits of using cPVB in addition to tPVB for this procedure.

IntroductionCryoneurolysis is the direct application of low temperatures to reversibly ablate peripheral nerves to provide pain relief. Recent development of a handheld cryoneurolysis device with small gauge probes and an integrated skin warmer broadens the clinical applications to include treatment of superficial nerves, further enabling treatments for pre-operative pain, post-surgical pain, chronic pain, and muscle movement disorders.Areas coveredCryoneurolysis is the direct application of cold temperatures to a peripheral nerve, resulting in reversible ablation due to Wallerian degeneration and nerve regeneration. Use over the last 50 years attests to a very low incidence of complications and adverse effects. Cryoprobes have traditionally been applied through a surgical incision; but, recent technical advances allow percutaneous administration. A new hand-held device is now approved for use within the United States. Cryoneurolysis has been used to treat postoperative and chronic pain states as well as spasticity. Expert commentary: Changes in the US healthcare system such as a push for the reduction of opioid use and the incorporation of Diagnostic Related Group codes, as well as recent technological advances including a handheld unit that allows for treatment of superficial nerves while protecting the skin from damage, may contribute to the resurgence of cryoneurolysis for the treatment of peripheral nerves.

BackgroundThe authors evaluated the efficacy of liposome bupivacaine in a femoral nerve block (FNB) after total knee arthroplasty.MethodsPart 1: subjects received FNB with 20 ml liposome bupivacaine (67, 133, or 266 mg) or placebo. Part 2: subjects were randomized to FNB with liposome bupivacaine 266 mg or placebo. The primary outcome measure was area under the curve of the numeric rating scale score for pain intensity at rest through 72 h (AUC NRS-R0-72) with imputed scores after rescue medication.ResultsIn part 1, FNB with liposome bupivacaine 266 mg (n = 24) resulted in analgesia similar to that obtained with 133 mg and was chosen for part 2. In part 2, least-squares mean (standard error) AUC NRS-R0-72 was lower with liposome bupivacaine 266 mg (n = 92) than with placebo (n = 91; 419 [17] vs. 516 [17]; P < 0.0001). This outcome remained unchanged in a post hoc analysis without score imputation (221 [12] vs. 282 [12]; P = 0.0005). Least-squares mean AUC NRS-R with imputed scores was lower with liposome bupivacaine during each 24-h interval (0 to 24, 24 to 48, and 48 to 72 h) after surgery; AUC NRS-R without imputed scores was lower during the 0- to 24-h and 24- to 48-h intervals. The liposome bupivacaine group had lower mean total opioid use (76 vs. 103 mg morphine; P = 0.0016). Pain was sufficiently severe to require second-step rescue with opioids via intravenously administered patient-controlled analgesia in 92% of liposome bupivacaine patients and 81% of placebo patients. With patient-controlled analgesia and other forms of rescue analgesia, mean NRS scores with activity were moderate in both liposome bupivacaine and placebo groups throughout the part 2 study period. Incidence of adverse events was similar between the groups (part 1: 90 vs. 96%; part 2: 96 vs. 96%, respectively).ConclusionFNB with liposome bupivacaine (266 mg) resulted in modestly lower pain scores and reduced opioid requirements after surgery, with an adverse event profile similar to placebo.

BackgroundMultiple 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 popliteal 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.MethodsPreoperatively, 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, followed 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.ResultsThe 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.ConclusionsFor 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.

BackgroundIt remains unknown whether continuous or scheduled intermittent bolus local anesthetic administration is preferable for adductor canal perineural catheters. Therefore, we tested the hypothesis that scheduled bolus administration is superior or noninferior to a continuous infusion on cutaneous knee sensation in volunteers.MethodsBilateral adductor canal catheters were inserted in 24 volunteers followed by ropivacaine 0.2% administration for 8 hours. One limb of each subject was assigned randomly to a continuous infusion (8 mL/h) or automated hourly boluses (8 mL/bolus), with the alternate treatment in the contralateral limb. The primary end point was the tolerance to electrical current applied through cutaneous electrodes in the distribution of the anterior branch of the medial femoral cutaneous nerve after 8 hours (noninferiority delta: -10 mA). Secondary end points included tolerance of electrical current and quadriceps femoris maximum voluntary isometric contraction strength at baseline, hourly for 14 hours, and again after 22 hours.ResultsThe 2 administration techniques provided equivalent cutaneous analgesia at 8 hours because noninferiority was found in both directions, with estimated difference on tolerance to cutaneous current of -0.6 mA (95% confidence interval, -5.4 to 4.3). Equivalence also was found on all but 2 secondary time points.ConclusionsNo evidence was found to support the hypothesis that changing the local anesthetic administration technique (continuous basal versus hourly bolus) when using an adductor canal perineural catheter at 8 mL/h decreases cutaneous sensation in the distribution of the anterior branch of the medial femoral cutaneous nerve.

Combined scientific advances in pharmaceutical agents, perineural blocks, and pump delivery capabilities such as those used with continuous peripheral nerve blocks have demonstrated advantages in pain management for patients undergoing joint arthroplasty. This report documents the incidence of falls increased after the implementation of a continuous peripheral nerve block program for patients undergoing knee and hip arthroplasty in an academic medical center.

Purpose of reviewTo review the evidence recently published involving the use of continuous peripheral nerve blocks (cPNBs) in the ambulatory setting.Recent findingsNew evidence exists involving the risks and benefits of cPNB in ambulatory patient populations such as pediatric ambulatory and postmastectomy patients. In addition, new related equipment is now available to facilitate ambulatory cPNB.SummaryRecent advancements in equipment for cPNB facilitate the usage in the ambulatory setting. Research-supported ambulatory cPNB indications have expanded to include pediatric subpopulations and major breast surgery, while further evidence mounts for its efficacy in patient populations with previously demonstrated benefits, such as foot, ankle and shoulder surgery.

BackgroundLiposome 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.MethodsData 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.ResultsOf 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).ConclusionsLiposome 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.

BackgroundWe 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.MethodsSubjects 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.ResultsSubjects 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).ConclusionsCompared 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.

BackgroundThe 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.MethodsSubjects 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.ResultsSubjects 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).ConclusionCompared 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.

BackgroundThe treatment of postoperative pain after mastectomy is an area of increasing interest, as this treatment option is now considered a standard of care for those affected by breast cancer. Thoracic paravertebral nerve block (tPVB) using local anesthetics administered before mastectomy can theoretically provide postoperative analgesia, thereby facilitating a more comfortable and shorter hospitalization.MethodsIn this retrospective cohort study, we aimed to determine the duration and degree to which tPVB provides postoperative analgesia in patients who underwent either unilateral or bilateral mastectomy (n = 182). We retrospectively examined the numeric rating scale (NRS) for pain scores recorded by nursing staff throughout individual patient hospitalizations, looking specifically at the following time points: arrival from the postanesthesia care unit to the surgical wards, noon on postoperative day 1 (POD1), and discharge. We also examined the number of days until patients were discharged from the hospital.ResultsOur results revealed a statistically significant decrease in NRS in pain scores for patients who had received a tPVB (n = 92) on arrival from the postanesthesia care unit to the surgical wards (mean NRS decrease of 1.9 points; 99% confidence interval [CI], -3.0 to -0.8; P < .001) but did not show statistically significant decreases in NRS for pain scores for patients at noon on POD1 (mean NRS decrease of 0.3 points at noon on POD1, P = .43) or at discharge (mean NRS decrease of 0.1 point at discharge, P = .65). Moreover, use of tPVB did not have an impact on time until discharge (average decrease of 0.5 hours; 95% CI, -6 to +5 hours, P = .87).ConclusionsSingle-injection tPVB appears to provide meaningful postoperative analgesia in the immediate postoperative period after mastectomy but not after the first day of surgery.

BackgroundIn a previous randomized, triple-masked, placebo-controlled study, the authors demonstrated that extending a single-injection paravertebral nerve block with a multiple-day perineural local anesthetic infusion improves analgesia and decreases pain-related dysfunction during the 3-day infusion but not subsequent to catheter removal within 1 month after mastectomy. This report describes a prospective follow-up study of the previously published trial to investigate the possibility that extending a single-injection paravertebral block with a multiple-day infusion may decrease persistent postsurgical pain as well as pain-induced emotional and functional dysfunction 1 year after mastectomy.MethodsSubjects undergoing uni- or bilateral mastectomy received unilateral (n = 24) or bilateral (n = 36) single-injection thoracic paravertebral block(s) with ropivacaine and perineural catheter(s). The subjects were randomized to receive either ropivacaine 0.4 % (n = 30) or normal saline (n = 30) via their catheters until the catheters were removed on postoperative day 3. Chronic pain and pain-related physical and emotional dysfunction were measured using the Brief Pain Inventory (BPI).ResultsNo statistically significant difference between treatments 3 months after surgery was observed with the BPI. In contrast, after 12 months, only 4 subjects (13 %) who had received a perineural ropivacaine infusion reported pain-induced dysfunction compared with 14 (47 %) who had received saline infusion (P = 0.011). At 12 months, the mean BPI was 1.6 ± 4.6 for the subjects who received ropivacaine versus 5.9 ± 11.3 for the subjects who received saline (P = 0.007).ConclusionsAdding a multiple-day, continuous ropivacaine infusion to a single-injection ropivacaine paravertebral nerve block may result in a lower incidence of pain as well as pain-related physical and emotional dysfunction 1 year after mastectomy.

BackgroundSingle-injection transversus abdominis plane (TAP) block provides postoperative analgesia and decreases supplemental analgesic requirements. However, there is currently no evidence from randomized, controlled studies investigating the possible benefits of continuous TAP blocks. Therefore, the aim of this randomized, triple-masked, placebo-controlled study was to determine if benefits are afforded by adding a multiple-day, ambulatory, continuous ropivacaine TAP block to a single-injection block following hernia surgery.MethodsPreoperatively, subjects undergoing unilateral inguinal (N=19) or peri-umbilical (N=1) hernia surgery received unilateral or bilateral TAP perineural catheter(s), respectively. All received a ropivacaine 0.5% (20 mL) bolus via the catheter(s). Subjects were randomized to either postoperative perineural ropivacaine 0.2% or normal saline using portable infusion pump(s). Subjects were discharged home where the catheter(s) were removed the evening of postoperative day (POD) 2. Subjects were contacted on POD 0-3. The primary endpoint was average pain with movement (scale: 0-10) queried on POD 1.ResultsTwenty subjects of a target 30 were enrolled due to the primary surgeon's unanticipated departure from the institution. Average pain queried on POD 1 for subjects receiving ropivacaine (N=10) was a mean (standard deviation) of 3.0 (2.6) vs 2.8 (2.7) for subjects receiving saline (N=10; 95% confidence interval difference in means -2.9 to 3.4; P=0.86). There were no statistically significant differences detected between treatment groups in any secondary endpoint.ConclusionsThe results of this study do not support adding an ambulatory, continuous ropivacaine infusion to a single-injection ropivacaine TAP block for hernia surgery. However, the present investigation was underpowered, and further study is warranted.

BackgroundWe 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.MethodsPreoperatively, 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.ResultsAverage 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.ConclusionsAfter 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.