Updated Retrospective Single-Center Comparative Analysis of Peripheral Nerve Block Complications Using Landmark Peripheral Nerve Stimulation Versus Ultrasound Guidance as a Primary Means of Nerve Localization.

OBJECTIVES: The purpose of this study was to perform an updated analysis of complications associated with upper and lower extremity peripheral nerve blocks (PNBs) performed with ultrasound (US) guidance versus the landmark approach. METHODS: We conducted a single-center retrospective cohort analysis to compare the incidence of PNB complications between the techniques. The primary outcome was local anesthetic systemic toxicity (LAST), whereas the secondary outcomes included short- and long-term nerve injuries. The current query included cases performed between 2012 and 2015. A combined analysis included data extending to 2006. The Statistical examination relied on the χ2 test. RESULTS: During this 4-year period, we performed 7789 US-guided and 498 landmark-guided blocks with no statistically significant difference in the incidence of nerve injury or LAST between the groups. Our 10-year analysis, however, revealed a significant increase (P < .01) in the rate of LAST with the landmark technique: 7 of 5932 versus 0 of 16,858 cases. The combined data also revealed a significant increase (P < .01) in short-term injuries associated with the landmark approach (30 of 5932 versus 33 of 16,858) but no significant difference in the incidence of long-term injuries. CONCLUSIONS: Our analysis supports a conclusion that the use of US guidance during PNBs leads to a significant reduction in the incidence of LAST, adding to growing evidence from similar investigations. The impact of US on the incidence of nerve injuries remains unclear, considering that the nature of transient deficits is thought to be multifactorial, and the frequency of lasting injuries did not differ significantly in this study.

Neurologic Outcomes After Low-Volume, Ultrasound-Guided Interscalene Block and Ambulatory Shoulder Surgery.

BACKGROUND AND OBJECTIVES: Postoperative neurologic symptoms after interscalene block and shoulder surgery have been reported to be relatively frequent. Reports of such symptoms after ultrasound-guided block have been variable. We evaluated 300 patients for neurologic symptoms after low-volume, ultrasound-guided interscalene block and arthroscopic shoulder surgery. METHODS: Patients underwent ultrasound-guided interscalene block with 16 to 20 mL of 0.5% bupivacaine or a mix of 0.2% bupivacaine/1.2% mepivacaine solution, followed by propofol/ketamine sedation for ambulatory arthroscopic shoulder surgery. Patients were called at 10 days for evaluation of neurologic symptoms, and those with persistent symptoms were called again at 30 days, at which point neurologic evaluation was initiated. Details of patient demographics and block characteristics were collected to assess any association with persistent neurologic symptoms. RESULTS: Six of 300 patients reported symptoms at 10 days (2%), with one of these patients having persistent symptoms at 30 days (0.3%). This was significantly lower than rates of neurologic symptoms reported in preultrasound investigations with focused neurologic follow-up and similar to other studies performed in the ultrasound era. There was a modest correlation between the number of needle redirections during the block procedure and the presence of postoperative neurologic symptoms. CONCLUSIONS: Ultrasound guidance of interscalene block with 16- to 20-mL volumes of local anesthetic solution results in a lower frequency of postoperative neurologic symptoms at 10 and 30 days as compared with investigations in the preultrasound period.

Neurotoxicity of common peripheral nerve block adjuvants.

PURPOSE OF REVIEW: This review outlines the analgesic role of perineural adjuvants for local anesthetic nerve block injections, and evaluates current knowledge regarding whether adjuvants modulate the neurocytologic properties of local anesthetics. RECENT FINDINGS: Perineural adjuvant medications such as dexmedetomidine, clonidine, buprenorphine, dexamethasone, and midazolam play unique analgesic roles. The dosing of these medications to prevent neurotoxicity is characterized in various cellular and in-vivo models. Much of this mitigation may be via reducing the dose of local anesthetic used while achieving equal or superior analgesia. Dose-concentration animal models have shown no evidence of deleterious effects. Clinical observations regarding blocks with combined bupivacaine-clonidine-buprenorphine-dexamethasone have shown beneficial effects on block duration and rebound pain without long-term evidence of neurotoxicity. In-vitro and in-vivo studies of perineural clonidine and dexmedetomidine show attenuation of perineural inflammatory responses generated by local anesthetics. SUMMARY: Dexmedetomidine added as a peripheral nerve blockade adjuvant improves block duration without neurotoxic properties. The combined adjuvants clonidine, buprenorphine, and dexamethasone do not appear to alter local anesthetic neurotoxicity. Midazolam significantly increases local anesthetic neurotoxicity in vitro, but when combined with clonidine-buprenorphine-dexamethasone (sans local anesthetic) produces no in-vitro or in-vivo neurotoxicity. Further larger-species animal testing and human trials will be required to reinforce the clinical applicability of these findings.

Outcomes of shoulder surgery in the sitting position with interscalene nerve block: a single-center series.

BACKGROUND: Several case reports have raised serious concerns about the safety of shoulder surgery in the beach-chair position, related to global cerebral hypoperfusion. We summarize our experiences with 15,014 cases of shoulder arthroscopy over an 11-year period. Our primary aim was to evaluate the incidence of intraoperative or immediate postoperative neurologic events and secondarily to relate other perioperative complications. METHODS: We searched our online deidentified departmental quality improvement and patient safety database for adverse outcomes associated with arthroscopic shoulder surgery performed in the beach-chair position for the 11-year period between April 2001 and November 2011, as well as our hospital-system database and a statewide database. This was compared with the total number of such cases, available from our department billing database. RESULTS: The total rate of adverse events was 0.37%. Neurologic abnormalities suggestive of acute cerebral ischemia or hemorrhage did not occur in the immediate perioperative period. One new neurologic deficit was reported, secondary to ischemic stroke, which occurred 24 hours after the surgery. The most frequent complications detected were unplanned return to care (0.067%), local anesthetic systemic toxicity (0.053%), and airway compromise requiring unplanned intubation (0.033%). Complications were infrequent and did not vary in incidence over the course of the study. CONCLUSIONS: This retrospective study suggests that intraoperative or immediate postoperative stroke is rare when surgery is conducted in beach-chair position in conjunction with regional anesthesia, propofol sedation, and spontaneous respiration via natural airway.

Adverse outcomes associated with nerve stimulator-guided and ultrasound-guided peripheral nerve blocks by supervised trainees: update of a single-site database.

BACKGROUND: We previously published a retrospective review of complications related to peripheral nerve blocks performed by supervised trainees, from our quality assurance and billing data, guided by either ultrasound, with nerve stimulator confirmation, or landmark-based nerve stimulator techniques. This report updates our results, for the period from May 2008 through December 2011, representing ongoing transition to near-complete combined ultrasound/nerve stimulator guidance in a block-oriented, outpatient orthopedic anesthesia practice. METHODS: We queried our deidentified departmental quality improvement electronic database for adverse outcomes associated with peripheral nerve blocks. Billing records were also deidentified and used to provide the denominator of total number of blocks using each technique of neurolocation. The types of blocks considered in this analysis were interscalene, axillary, femoral, sciatic, and popliteal-sciatic blocks. Nerve block complications based on each type of guidance were then compared for the entire recent 30-month time period, as well as for the 6-year period of this report. RESULTS: There were 9062 blocks performed by ultrasound/nerve stimulator, and 5436 by nerve stimulator alone over the entire 72-month period. Nerve injuries lasting longer than 1 year were rare, but similar in frequency with both nerve guidance techniques. The incidence of local anesthetic systemic toxicity was found to be higher with landmark-nerve stimulator technique than with use of ultrasound-guided nerve blocks (6/5436 vs 0/9069, P = 0.0061). CONCLUSIONS: We report a large series of combined ultrasound/nerve stimulator nerve blocks by supervised trainees without major local anesthetic systemic toxicity. While lacking the compelling evidence of randomized controlled trials, this observational database nonetheless allows increased confidence in the safety of using combined ultrasound/nerve stimulator in the setting of anesthesiologists-in-training.

Adverse outcomes associated with stimulator-based peripheral nerve blocks with versus without ultrasound visualization.

BACKGROUND AND OBJECTIVES: In this retrospective study, we queried our Quality Improvement database of anesthetic-related complications to evaluate the frequency of noncatheter peripheral nerve block-related adverse occurrences. We hypothesized that adverse complications of nerve blockade are less common when ultrasonography is used in conjunction with peripheral nerve stimulation to guide needle placement, when compared with the sole use of physical landmarks and nerve stimulation. METHODS: We queried our departmental Quality Improvement electronic database for adverse outcomes associated with peripheral nerve blocks. Billing records were used to provide the denominator of the total number of blocks using both techniques of neurolocation. The types of blocks considered in this analysis were interscalene, axillary, femoral, sciatic, and popliteal sciatic blocks. The total numbers of complications of nerve blockade with each type of guidance were then compared, as were specific subsets of adverse effects. RESULTS: There were 5436 consecutive peripheral noncatheter block cases (interscalene, axillary, femoral, sciatic, popliteal) during the 28-month period surveyed, with 3290 guided by landmark-nerve stimulation, and 2146 by ultrasound-nerve stimulation. Eight adverse outcomes occurred among patients having blocks guided by landmark-nerve stimulation technique, including 5 seizures and 3 nerve injuries. There were no such occurrences in the ultrasound-nerve stimulation group. When comparing the 4 brachial plexus block-related seizures that occurred with landmark guidance versus none with ultrasound guidance, the associated risk of seizures reached statistical significance (P = 0.044 by Fisher exact test). There was no difference between the 2 groups in the number of seizures occurring with lower extremity blocks, or in the frequency of neurologic injury. CONCLUSIONS: High-definition ultrasonography offers potential advantages in the administration of peripheral nerve blockade. The significant difference in major central nervous system local anesthetic toxicity observed in this study supports the use of ultrasound guidance in conjunction with peripheral nerve stimulation to provide brachial plexus peripheral nerve blockade in an academic, ambulatory anesthesia practice.

General health and knee function outcomes from 7 days to 12 weeks after spinal anesthesia and multimodal analgesia for anterior cruciate ligament reconstruction.

BACKGROUND: We previously reported that continuous perineural femoral analgesia reduces pain with movement during the first 2 days after anterior cruciate ligament reconstruction (ACLR, n = 270), when compared with multimodal analgesia and placebo perineural femoral infusion. We now report the prospectively collected general health and knee function outcomes in the 7 days to 12 wk after surgery in these same patients. METHODS: At three points during 12 wk after ACLR surgery, patients completed the SF-36 General Health Survey, and the Knee Outcome Survey (KOS). Generalized Estimating Equations were implemented to evaluate the association between patient-reported survey outcomes and (1) preoperative baseline survey scores, (2) time after surgery, and (3) three nerve block treatment groups. RESULTS: Two hundred seventeen patients' data were complete for analysis. In univariate and multiple regression Generalized Estimating Equations models, nerve block treatment group was not associated with SF-36 and KOS scores after surgery (all with P > or = 0.05). The models showed that the physical component summary of the SF-36 (P < 0.0001) and the KOS total score (P < 0.0001) increased (improved) over time after surgery and were also influenced by baseline scores. CONCLUSIONS: After spinal anesthesia and multimodal analgesia for ACLR, the nerve block treatment group did not predict SF-36 or knee function outcomes from 7 days to 12 wk after surgery. Further research is needed to determine whether these conclusions also apply to a nonstandardized anesthetic, or one that includes general anesthesia and/or high-dose opioid analgesia.

Ultrasound guidance with nerve stimulation reduces the time necessary for resident peripheral nerve blockade.

BACKGROUND AND OBJECTIVES: Educating residents in peripheral nerve blockade may impact the efficiency of a busy regional anesthesia service. Ultrasound guidance may affect the efficiency and effectiveness of nerve block. We examined the impact of ultrasound guidance on resident performance of peripheral nerve block in a regional anesthesia rotation. METHODS: An existing de-identified database was used for retrospective analysis of resident performance of interscalene, axillary, femoral, and popliteal nerve blocks, by peripheral nerve stimulator guidance alone and by nerve stimulator aided by ultrasound. The primary variable examined was the time required to perform the block. Others variables included (1) number of needle insertions; (2) proportion of blocks in which there was a blood vessel puncture; and (3) block efficacy. Peripheral nerve-stimulator blocks were guided by surface anatomy and motor stimulation, refined to 0.2 to 0.5 mA of current before injection of local anesthetic, while ultrasound nerve stimulator blocks were confirmed using a current of 0.5 mA. RESULTS: Ultrasound-aided blocks required less time to perform (median = 1.8 min) than nerve stimulator-guided blocks (median = 6.5 min, P < .001). More needle insertions were required for nerve localization in the nerve stimulator-guided blocks (median = 6) than in ultrasound-aided blocks (median = 2; P < .001). There were fewer blood vessel punctures with ultrasound-aided blocks (P = .03). CONCLUSIONS: During resident teaching, ultrasound-aided peripheral nerve-stimulated block required less time to perform than did nerve-stimulator-guided blocks. Fewer needle insertions were required to perform the ultrasound-guided blocks, and there were fewer blood vessel punctures when ultrasound was used.

Eliminating postoperative nausea and vomiting in outpatient surgery with multimodal strategies including low doses of nonsedating, off-patent antiemetics: is "zero tolerance" achievable?

For ondansetron, dexamethasone, and droperidol (when used for prophylaxis), each is estimated to reduce risk of postoperative nausea and/or vomiting (PONV) by approximately 25%. Current consensus guidelines denote that patients with 0-1 risk factors still have a 10-20% risk of encountering PONV, but do not yet advocate routine prophylaxis for all patients with 10-20% risk. In ambulatory surgery, however, multimodal prophylaxis has gained favor, and our previously published experience with routine prophylaxis has yielded PONV rates below 10%. We now propose a "zero-tolerance" antiemetic algorithm for outpatients that involves routine prophylaxis by first avoiding volatile agents and opioids to the extent possible, using locoregional anesthesia, multimodal analgesia, and low doses of three nonsedating off-patent antiemetics. Routine oral administration (immediately on arrival to the ambulatory surgery suite) of perphenazine 8 mg (antidopaminergic) or cyclizine 50 mg (antihistamine), is followed by dexamethasone 4 mg i.v. after anesthesia induction (dexamethasone is avoided in diabetic patients). At the end of surgery, ondansetron (4 mg i.v., now off-patent) is added. Rescue therapy consists of avoiding unnecessary repeat doses of drugs acting by the same mechanism: haloperidol 2 mg i.v. (antidopaminergic) is prescribed for patients pretreated with cyclizine or promethazine 6.25 mg i.v. (antihistamine) for patients having been pretreated with perphenazine. If available, a consultation for therapeutic acupuncture procedure is ordered. Our approach toward "zero tolerance" of PONV emphasizes liberal identification of and prophylaxis against common risks.

Routine multimodal antiemesis including low-dose perphenazine in an ambulatory surgery unit of a university hospital: a 10-year history. Supplement to: Eliminating postoperative nausea and vomiting in outpatient surgery with multimodal strategies including low doses of nonsedating, off-patent antiemetics: is "zero tolerance" achievable?

For 10 years, we have used intravenous and oral perphenazine as part of a multimodal antiemetic prophylaxis care plan for at least 10,000 outpatients. We have never encountered an adverse event, to our knowledge, when the intravenous dose was less than or equal to 2 mg, or when the single preoperative oral dose did not exceed 8 mg (with no repeated dosing). As a single-dose component of multimodal antiemetic prophylaxis therapy, we believe that this track record of anecdotal safety in adults who meet certain criteria (age 14-70, no less than 45 kg, no history of extrapyramidal reactions or of Parkinson disease, and no Class III antidysrhythmic coadministered for coexisting disease) constitutes a sufficient patient safety basis for formal prospective study. We believe that future perphenazine studies should include routine coadministration with prospectively established multimodal antiemetics (i.e., dexamethasone and a 5-HT3 antagonist). In settings where droperidol is still routinely used and deemed acceptable by local scientific ethics committees, we believe that oral perphenazine 8 mg should be compared head to head with droperidol 0.625-1.25 mg in patients receiving coadministered dexamethasone and 5-HT3 antagonists in order to determine differences in synergistic efficacy, if any. Similar trials should be performed, individually evaluating cyclizine, transdermal scopolamine, and aprepitant in combination with coadministered dexamethasone and a 5-HT3 antagonist. Such studies should also quantify efficacy in preventing nausea and vomiting after discharge home, and also quantify the extent to which the prophylaxis plans reduce postanesthesia care unit (PACU) requirements (i.e., increase PACU bypass), reduce the need for any nursing interventions for postoperative nausea and/or vomiting (PONV), and influence the extent to which any variable costs of postoperative nursing care are reduced.

Rebound pain scores as a function of femoral nerve block duration after anterior cruciate ligament reconstruction: retrospective analysis of a prospective, randomized clinical trial.

BACKGROUND AND OBJECTIVES: Continuous perineural femoral analgesia has been reported to reduce numeric rating pain scores (NRS, scale 0-10) after anterior cruciate ligament reconstruction (ACLR). In the current study, we determined rebound pain scores in autograft ACLR outpatients after nerve block analgesia resolved. METHODS: After standardized spinal anesthesia and perioperative multimodal analgesia, patients received a femoral perineural catheter and 50 hours of saline or levobupivacaine. All patients received levobupivacaine (30 mL of 0.25% as a bolus) before the infusion. Patients completed a pain diary for 6 days, indicating serial NRS scores and perceptions of when nerve block analgesia resolved. Block duration and rebound pain scores were computed. RESULTS: Data from 84 participants' pain diaries were analyzed. Patients receiving saline infusion reported mean nerve block duration of 37 hours versus 59 hours for patients receiving the levobupivacaine infusion (P < .001). Mean rebound pain scores increased by 2.0 (95% confidence interval, 1.6-2.4). Based on the computations used to derive block duration and rebound pain scores, each hour of additional block duration was predictive of a 0.03-unit reduction in rebound pain scores. CONCLUSIONS: In an anesthesia care protocol consisting of spinal anesthesia and multimodal analgesia during and after autograft ACL reconstruction, approximately 33 hours of additional nerve block duration were required to reduce rebound pain scores by one unit. Further study is required to determine rebound pain score differences when other local anesthetics and anesthetic/analgesic plans are being used and when other surgeries are being performed.

Nausea, vomiting, sleep, and restfulness upon discharge home after outpatient anterior cruciate ligament reconstruction with regional anesthesia and multimodal analgesia/antiemesis.

BACKGROUND AND OBJECTIVES: We analyzed discharge outcome data after anterior cruciate ligament reconstruction (ACLR) under spinal anesthesia including a perineural femoral catheter and multimodal analgesia/antiemesis. The outcomes specifically addressed in this report are nausea, vomiting, and retching (NVR) and quality of sleep/difficulty falling asleep/daytime restfulness. METHODS: ACLR patients were randomized to saline or 0.25% levobupivacaine as a bolus and/or 50-hour infusion. Patients completed the Quality of Recovery 40-item (QoR-40) survey on postoperative days 1 to 4. We analyzed predictors of perfect responses (i.e., no NVR and perfect sleep-restfulness) by pooling these specific QoR-40 items. Prospectively collected QoR-40 data were analyzed retrospectively. RESULTS: Data from 233 participants were analyzed. The addition of the femoral nerve block or perineural catheter did not predict associated improvements in NVR or sleep-restfulness. Previous days' NVR was the most consistent predictor of subsequent NVR, whereas gender and opioid consumption were less consistent predictors. Smoking status was not predictive of NVR. Previous days' sleep-restfulness was a consistent predictor of subsequent sleep-restfulness, whereas the presence of any moderate pain was a less consistent predictor of sleep-restfulness. CONCLUSIONS: NVR and quality of sleep-restfulness after the described regional anesthetic with multimodal analgesia and antiemesis is reported. Smoking status was not a predictor of NVR, and gender and opioid consumption were not consistently predictive of NVR. The addition of a femoral nerve block to the described multimodal technique was not associated with NVR or quality of sleep-restfulness.

Reduction of verbal pain scores after anterior cruciate ligament reconstruction with 2-day continuous femoral nerve block: a randomized clinical trial.

BACKGROUND: Single-injection femoral nerve block analgesia and spinal anesthesia have been associated with fewer postoperative nursing interventions and successful same-day discharge after anterior cruciate ligament reconstruction. In the current study, the authors prospectively determined the effect of continuous femoral nerve block on a numeric rating scale (NRS) of pain intensity with movement for 7 postoperative days. METHODS: Patients undergoing this surgery with no history of previous invasive surgery on the same knee were recruited for this study. After standardized spinal anesthesia, intravenous sedation, and perioperative multimodal analgesia, patients received a femoral nerve catheter with (1) saline bolus (30 ml) plus saline infusion (270 ml at 5 ml/h, placebo group); (2) levobupivacaine (0.25%) bolus with saline infusion (group I), or (3) levobupivacaine (0.25%) bolus and infusion (group II). Patients were surveyed preoperatively and on postoperative days 1-4 and 7 to determine NRS scores (scale 0-10). RESULTS: Data from 233 participants were analyzed. On days 1-2, 50% of placebo patients had NRS scores of 5 or above, whereas among group II patients, only 25% had scores of 5 or above (P < 0.001). In regression models for NRS scores during days 1-4, group II was the only factor predicting lower pain scores (odds ratios, 0.3-0.5; P = 0.001-0.03). Overall, patients with preoperative NRS scores greater than 2 were likely to report higher NRS scores during days 1-7 (odds ratios, 3.3-5.2; P < 0.001). CONCLUSIONS: Femoral nerve block catheters reliably keep NRS scores below the moderate-to-severe pain threshold for the first 4 days after anterior cruciate ligament reconstruction.