Francis V. Salinas

The ASRA evidence-based medicine assessment of ultrasound-guided regional anesthesia and pain medicine: Executive summary.

Objectives: The American Society of Regional Anesthesia and Pain Medicine charged an expert panel to examine the evidence basis for ultrasound guidance as a nerve localization tool in the clinical practices of regional anesthesia and interventional pain medicine. Methods: The panel searched, examined, and assessed the literature of ultrasound-guided regional anesthesia (UGRA) from the past 20 years. The qualities of studies were graded using the Jadad score. Strength of evidence and recommendations were graded using an accepted rating tool. Results: The panel made specific literature-based assessments concerning the relative advantages and limitations of UGRA relative to traditional nerve localization methods as they pertained to block characteristics and complications. Assessments and recommendations were made for upper and lower extremity, neuraxial, and truncal blocks and include pediatrics and interventional pain medicine. Conclusions: Ultrasound guidance improves block characteristics (particularly performance time and surrogate measures of success) that are often block specific and that may impart an efficiency advantage depending on individual practitioner circumstances. Evidence for UGRA impacting patient safety is currently limited to the demonstration of improvements in the frequency of surrogate events for serious complications.

The Effect of Single-Injection Femoral Nerve Block Versus Continuous Femoral Nerve Block After Total Knee Arthroplasty on Hospital Length of Stay and Long-Term Functional Recovery Within an Established Clinical Pathway

Total knee arthroplasty (TKA) may result in severe pain, and single-injection femoral nerve blocks (SFNB) have been demonstrated to have a limited duration of analgesia. Continuous femoral nerve blocks (CFNB) can prolong the analgesic duration of SFNB. We prospectively randomized 36 patients undergoing TKA to CFNB versus SFNB and evaluated the effect on hospital length of stay (LOS) as the primary outcome within a standardized clinical pathway. Secondary outcomes included visual analog scale (VAS) pain scores, opioid consumption, and long-term functional recovery at 12 wk. Mean VAS resting scores were significantly lower among patients who received CFNB versus SFNB: first day (1.7 vs 3.3 [P = 0.002]) and second day (0.9 vs 3.2 [P < 0.0001]) after surgery. Mean maximal VAS scores during physical therapy were significantly lower among patients who received CFNB versus SFNB: first day (4.7 vs 6.3 [P = 0.01]) and second day (3.9 vs 6.1 [P = 0.0005]) after surgery. Mean oxycodone consumption was significantly lower among patients who received CFNB versus SFNB: 15 mg versus 40 mg (P = < 0.0001) on the first day after surgery; 20 mg versus 43 mg (P = 0.0004) on the second day after surgery. There was no difference in hospital LOS (3.8 vs 3.9 days) or long-term functional recovery (117° versus 113° knee flexion at 12 wk) between the two groups. The lack of effect provided by increased duration of analgesia (from CFNB) after TKA may now have minimal impact on hospital LOS and long-term functional recovery in the contemporary healthcare environment within the United States.

Continuous plexus and peripheral nerve blocks for postoperative analgesia

T here is increasing interest in peripheral nerve blocks because of potential benefits and concerns over interactions of anticoagulants and central neuraxial techniques. In a recent survey of members of the American Society of Anesthesiologists and the American Society of Regional Anesthesia and Pain Medicine, nearly half of the respondents anticipated an increased use of peripheral nerve blocks in their practice (1). Continuous plexus and peripheral nerve blocks offer the potential benefits of prolonged analgesia with fewer side effects, greater patient satisfaction, and faster functional recovery after surgery. In this review article, we summarize pertinent anatomy, technical aspects, and current evidence when available in prospective randomized trials for the indications and efficacy of continuous perineural techniques for postoperative analgesia.

Evidence basis for regional anesthesia in multidisciplinary fast-track surgical care pathways.

Fast-track programs have been developed with the aim to reduce perioperative surgical stress and facilitate patients recovery after surgery. Potentially, regional anesthesia and analgesia techniques may offer physiological advantages to support fast-track methodologies in different type of surgeries. The aim of this article was to identify and discuss potential advantages offerred by regional anesthesia and analgesia techniques to fast-track programs. In the first section, the impact of regional anesthesia on the main elements of fast-track surgery is addressed. In the second section, procedure-specific fast-track programs for colorectal, hernia, esophageal, cardiac, vascular, and orthopedic surgeries are presented. For each, regional anesthesia and analgesia techniques more frequently used are discussed. Furthermore, clinical studies, which included regional techniques as elements of fast-track methodologies, were identified. The impact of epidural and paravertebral blockade, spinal analgesia, peripheral nerve blocks, and new regional anesthesia techniques on main procedure-specific postoperative outcomes is discussed. Finally, in the last section, implementations required to improve the role of regional anesthesia in the context of fast-track programs are suggested, and issues not yet addressed are presented.

Location, location, location: Continuous peripheral nerve blocks and stimulating catheters.

Continuous peripheral nerve blocks offer the potential benefits of extended site-specific postoperative analgesia, few side effects, improved patient satisfaction, and accelerated functional recovery after extremity surgery.1 Continuous peripheral nerve blocks provide superior analgesia compared with intravenous patient-controlled analgesia and a lower incidence of side effects compared with either intravenous patient-controlled analgesia or continuous lumbar epidural analgesia.2-5 Prospective, randomized clinical studies have demonstrated the effectiveness of ambulatory continuous peripheral blocks after painful orthopedic procedures.6,7 A major concern with the use of continuous peripheral nerve block is placement of the catheter close enough to the nerve to allow effective analgesia with the small amounts of dilute local anesthetic solutions utilized for the “secondary analgesic block” after the initial primary anesthetic block has resolved. Large case series have demonstrated failed secondary block in up to 10% of patients, despite receiving a large bolus of concentrated local anesthetic.8,9 Recent studies using injected contrast media exiting at the catheter tip have demonstrated that despite the ease of “successful insertion,” the direction of continuous femoral catheters is unpredictable.9,10 Given the expected increase in the clinical use of continuous peripheral blocks, a reliable method to immediately verify correct peripheral catheter position is needed to prevent secondary analgesic block failures. Otherwise, patients will be subject to a technique with possible risks, but no benefit. Traditionally, correct catheter placement has been confirmed by testing for a clinical effect of satisfactory analgesia and or by sensory modality testing within the desired sensory distribution. Many continuous studies have initiated primary block via the stimulating needle, followed simply by blind insertion of the peripheral catheter 5 to 15 cm beyond the needle tip. Communication with colleagues who have significant experience in placing peripheral catheters reveals up to 40% secondary analgesic block failure rate (via the peripheral catheter infusion). My personal experience with placing continuous peripheral catheters confirms this impression. In order to avoid secondary block failure, the primary block can be injected through the peripheral catheter. Lack of satisfactory anesthesia after injection of local anesthetic would then indicate an improperly positioned catheter prior to initiating continuous perineural analgesia. However, even this approach may require several attempts to localize the peripheral nerve and then correctly place the catheter, as well as injection of an additional bolus of local anesthetic. In this issue of Regional Anesthesia and Pain Medicine, Pham-Dang et al.11 report an observational study of 130 patients designed to evaluate the effectiveness of stimulating catheters used to immediately verify and confirm correct catheter placement. In their study, once the stimulating needle localized the peripheral

Anatomic basis to the ultrasound-guided approach for saphenous nerve blockade.

Background and Objectives: Successful blockade of the saphenous nerve using surface landmarks can be challenging. We evaluated the anatomic basis of performing a saphenous nerve block with ultrasound (US) using its relationship to the saphenous branch of descending genicular artery, sartorius muscle, and the adductor hiatus as defined by cadaveric measurements. Methods: Using a total of 9 cadaveric knee dissections, the saphenous nerve and its relationship to the saphenous branch of the descending genicular artery (SBDGA) were examined. The distances from the patella to the distal end of the adductor canal and the bifurcation of the saphenous nerve were recorded. US images of an above-the-knee, subsartorial saphenous nerve block were reviewed. Results: The saphenous nerve coursed with the SBDGA. It exited the adductor canal at a median of 10.25 cm (range, 7.0-11.5 cm) cephalad to the proximal patellar border and traveled closely with the SBDGA. At its bifurcation into the infrapatellar branch and sartorial branch, the saphenous nerve was at its closest approximation to the SBDGA. This point was found to be at a median of 2.7 cm (range, 2.1-3.4 cm) cephalad and a median of 6.6 cm (range, 5.0-9.0 cm) posterior to the proximal and posterior patellar border, respectively. Conclusions: The US-guided approach for saphenous nerve blockade using its close anatomic relationship to the SBDGA is a feasible alternative to previously described surface landmark-based or US-guided paravenous approaches.

Parasternal block and local anesthetic infiltration with levobupivacaine after cardiac surgery with desflurane: the effect on postoperative pain, pulmonary function, and tracheal extubation times.

Early tracheal extubation has become common after cardiac surgery. Anesthetic techniques designed to achieve this goal can make immediate postoperative analgesia challenging. We conducted this randomized, placebo-controlled, double-blind study to investigate the effect of a parasternal block on postoperative analgesia, respiratory function, and extubation times. We enrolled 20 patients having cardiac surgery via median sternotomy; 17 patients completed the study. A de-sflurane-based, small-dose opioid anesthetic was used. Before sternal wire placement, the surgeons performed the parasternal block and local anesthetic infiltration of sternotomy and tube sites with either 54 mL of saline placebo or 54 mL of 0.25% levobupivacaine with 1:400,000 epinephrine. Effects on pain and respiratory function were studied over 24 h. Patients in the levobupivacaine group used significantly less morphine in the first 4 h after surgery (20.8 ± 6.2 mg versus 33.2 ± 10.9 mg in the placebo group; P = 0.013); they also had better oxygenation at the time of extubation. Four of nine in the placebo group needed rescue pain medication, versus none of eight in the levobupivacaine group (P = 0.08). Peak serum levobupivacaine concentrations were below potentially toxic levels in all patients (0.64 ± 0.43 &mgr;g/mL; range, 0.24–1.64 &mgr;g/mL). Parasternal block and local anesthetic infiltration of the sternotomy wound and mediastinal tube sites with levobupivacaine can be a useful analgesic adjunct for patients who are expected to undergo early tracheal extubation after cardiac surgery.

Ultrasound and Review of Evidence for Lower Extremity Peripheral Nerve Blocks

This qualitative systematic review summarizes existing evidence from randomized controlled trials (RCTs) comparing ultrasound (US) to alternative techniques for lower extremity peripheral nerve block. There were 11 RCTs of sufficient quality for inclusion. Jadad scores ranged from 1 to 4 with a median of 3. For femoral nerve blocks, US provided shorter onset and improved quality of sensory and motor block, as well as a decrease in local anesthetic requirements. For sciatic nerve blocks, US resulted in a higher percentage of patients with complete sensory and motor block, as well as decreased local anesthetic requirements. In 2 of the studies for sciatic nerve block, US resulted in a shorter time to successfully complete the procedure. No study was powered to detect a difference in surgical block success. Overall, there was significant heterogeneity in the definitions of successful sensory and motor block. In 2 studies, the optimal peripheral nerve stimulation technique may have not been used, resulting in a potential bias. No RCT reported US as inferior to alternative techniques in any outcome. There is level Ib evidence to make a grade A recommendation that US guidance provides improvements in onset and success of sensory block, a decrease in local anesthetic requirements, and decreased time to perform lower extremity peripheral nerve blocks.

The Second American Society of Regional Anesthesia and Pain Medicine Evidence-Based Medicine Assessment of Ultrasound-Guided Regional Anesthesia: Executive Summary.

Objectives: In 2009 and again in 2012, the American Society of Regional Anesthesia and Pain Medicine assembled an expert panel to assess the evidence basis for ultrasound guidance as a nerve localization tool for regional anesthesia. Methods: The 2012 panel reviewed evidence from the first advisory but focused primarily on new information that had emerged since 2009. A new section was added regarding the accuracy and reliability of ultrasound for determining needle-to-nerve proximity. Jadad scores are used to rank study quality. Grades of recommendations consistent with their level of evidence are provided. Results: The panel offers recommendations based on synthesis and analysis of literature related to (1) the technical capabilities of ultrasound equipment and its operators, (2) comparison of ultrasound to other methods of nerve localization with regard to block characteristics, (3) comparison of block techniques where ultrasound is the sole nerve localization modality, and (4) major complications. Assessment of evidence strength and recommendations are made for upper- and lower-extremity, truncal, neuraxial, and pediatric blocks. Conclusions: Scientific evidence from the past 5 years has clarified and strengthened our understanding of ultrasound-guided regional anesthesia as a nerve localization tool. High-level evidence supports ultrasound guidance contributing to superior characteristics with selected blocks, although absolute differences with the comparator technique are often relatively small (especially for upper-extremity blocks). The clinical meaningfulness of these differences is likely of variable importance to individual practitioners. The use of ultrasound significantly reduces the risk of local anesthetic systemic toxicity as well as the incidence and intensity of hemidiaphragmatic paresis, but has no significant effect on the incidence of postoperative neurologic symptoms. Whats New in This Update? This evidence-based assessment of ultrasound-guided regional anesthesia reviews findings from our 2010 publication and focuses on new meta-analyses, randomized controlled trials, and large case series published since 2009. New to this exercise is an in-depth analysis of the accuracy and reliability of ultrasound guidance for identifying needle-to-nerve relationships. This version no longer addresses ultrasound for interventional pain medicine procedures, because the growth of that field demands separate consideration. Since our 2010 publication, new information has either supported or strengthened our original conclusions. There is no evidence that ultrasound is inferior to alternative nerve localization methods.

A tale of two needle passes.

ltrasound-guided regional anesthesia (UGRA) is an evolving technique with the promise of more rapid and complete block onset, increased block success ates, increased efficiency and patient comfort during needle manipulation, and erhaps a decrease in block-related complications. These potential advantages are ade possible by real-time visualization of neural and perineural structures, eedle tip advancement, and perineural distribution of local anesthetic. Despite he allure and perceived advantages of UGRA, which have led some enthusiastic arly adopters to incorporate its use to the complete exclusion of peripheral nerve timulation (PNS), its widespread acceptance into daily clinical practice will likely epend upon 2 major factors. First, skeptics will correctly demand more substanive scientific evidence of the purported benefits of UGRA. Second, the more ractical among us will be swayed by cost-effectiveness, equipment availability, nd the very real issue of how trainees and practicing anesthesiologists learn and erfect the knowledge base and manual dexterity that UGRA requires. The study of Kapral et al. in this issue of Regional Anesthesia and Pain Medicine is n example of the kind of randomized clinical trial (RCT) required to support the roposed advantages of UGRA.1 However, it also demonstrates how study design nd choice of endpoints for comparing 2 different regional techniques can influnce a study’s outcome. In their large RCT of patients undergoing trauma-related urgery of the shoulder and upper arm, the authors compared ultrasound guidnce (USG) to PNS for onset of sensory and motor block within 30 minutes and ore importantly “block failure,” which they defined as pain following skin ncision requiring conversion to general anesthesia. Surgical anesthesia was chieved in significantly more patients (98.8%; 79/80) in the USG group comared with the PNS group (91.3%; 73/80). Onset of sensory and motor block was lso significantly faster in the USG group. During performance of USG interscalene brachial plexus block, Kapral et al. dvanced the needle under direct visualization into the interscalene space in close roximity to the nerve roots. If the spread of local anesthetic did not incorporate ll of the nerve roots (from C5 to T1), the needle tip was repositioned (in almost 0% of subjects) to achieve the desired distribution. Conversely, in the PNS group he entire volume of local anesthetic was delivered after eliciting a single motor esponse of the forearm or hand. This difference in technique is notable for several easons. First, the PNS response may have influenced the results because the uthors chose a motor response corresponding anatomically with the middle or ower trunks, while shoulder surgery ideally requires that the upper trunk is locked. Indeed, the surgical site remained unanesthetized in 7 of the 80 patients n the PNS group. Second, as the authors stated, “. . . ultrasound-guided interscalene lexus block is, contrary to the nerve stimulator guided method, a multi-injection techique.” We should not be surprised then that ultrasound guidance led to a higher urgical success rate and a more complete blockade. While the decision to comare multiple injection USG interscalene block to single injection PNS block for houlder surgery may reflect “real world practice,” it is “unfair” when comparing verall success rates. Peripheral nerve stimulation interscalene block has always een a single injection technique that typically deposits local anesthetic closer to