Richard Brull

Neurological complications after regional anesthesia: contemporary estimates of risk.

BACKGROUND:Regional anesthesia (RA) provides excellent anesthesia and analgesia for many surgical procedures. Anesthesiologists and patients must understand the risks in addition to the benefits of RA to make an informed choice of anesthetic technique. Many studies that have investigated neurological complications after RA are dated, and do not reflect the increasing indications and applications of RA nor the advances in training and techniques. In this brief narrative review we collate the contemporary investigations of neurological complications after the most common RA techniques. METHODS:We reviewed all 32 studies published between January 1, 1995 and December 31, 2005 where the primary intent was to investigate neurological complications of RA. RESULTS:The sample size of the studies that investigated neurological complications after central and peripheral (PNB) nerve blockade ranged from 4185 to 1,260,000 and 20 to 10,309 blocks, respectively. The rate of neuropathy after spinal and epidural anesthesia was 3.78:10,000 (95% CI: 1.06–13.50:10,000) and 2.19:10,000 (95% CI: 0.88–5.44:10,000), respectively. For common PNB techniques, the rate of neuropathy after interscalene brachial plexus block, axillary brachial plexus block, and femoral nerve block was 2.84:100 (95% CI 1.33–5.98:100), 1.48:100 (95% CI: 0.52–4.11:100), and 0.34:100 (95% CI: 0.04–2.81:100), respectively. The rate of permanent neurological injury after spinal and epidural anesthesia ranged from 0–4.2:10,000 and 0–7.6:10,000, respectively. Only one case of permanent neuropathy was reported among 16 studies of neurological complications after PNB. CONCLUSIONS:Our review suggests that the rate of neurological complications after central nerve blockade is <4:10,000, or 0.04%. The rate of neuropathy after PNB is <3:100, or 3%. However, permanent neurological injury after RA is rare in contemporary anesthetic practice.

Ultrasound guidance improves success rate of axillary brachial plexus block.

PurposeThe purpose of this study is to determine if real time ultrasound guidance improves the success rate of axillary brachial plexus blockade.MethodsPatients undergoing elective hand surgery were randomly assigned to one of three groups. Axillary blocks were performed using three motor response endpoints in the nerve stimulator (NS) Group, real-time ultrasound guidance in the ultrasound (US) Group and combined ultrasound and nerve stimulation in the USNS Group. Following administration of a standardized solution containing 2% lidocaine with 1:200,000 epinephrine and 0.5% bupivacaine (total 42 mL), sensory and motor functions were assessed by a blinded observer every five minutes for 30 min. A successful block was defined as complete sensory loss in the median, radial and ulnar nerve distribution by 30 min. The need for local and general anesthesia supplementation and post-block adverse events were documented.ResultsOne hundred and eighty-eight patients completed the study. Block success rate was higher in Groups US and USNS (82.8% and 80.7%) than Group NS (62.9%) (P = 0.01 and 0.03 respectively). Fewer patients in Groups US and USNS required supplemental nerve blocks and/or general anesthesia. Postoperatively, axillary bruising and pain were reported more frequently in Group NS.ConclusionThis study demonstrates that ultrasound guidance, with or without concomitant nerve stimulation, significantly improves the success rate of axillary brachial plexus block.RésuméObjectifLe but de cette étude est de déterminer si l’échoguidage en temps réel améliore le taux de succès du bloc du plexus brachial par approche axillaire.MéthodeDes patients devant subir une chirurgie élective de la main ont été randomisés en trois groupes. Des blocs axillaires ont été effectués en utilisant: trois points de réponses motrices dans le groupe neurostimulateur (NS), l’échoguidage en temps réel dans le groupe échographie (EG), et l’échographie combinée à la stimulation nerveuse dans le troisième groupe (EGNS). Suite à l’administration d’une solution standardisée contenant de la lidocaïne 2 % avec épinéphrine (1:200 000) et de la bupivacaïne 0,5 % (total 42 mL), les fonctions sensitives et motrices ont été évaluées par un observateur neutre toutes les cinq minutes pendant 30 min. Un bloc réussi a été défini comme la perte complète de sensation dans la distribution des nerfs médian, radial et cubital après 30 min. La nécessité d’une anesthésie locale et générale supplémentaire ainsi que les effets négatifs post-bloc ont été documentés.RésultatChez les 188 patients qui ont terminé l’étude, le taux de succès du bloc a été plus élevé dans les groupes EG et EGNS (82,8 % et 80,7 %) que dans le groupe NS (62,9 %) (P) =0,01 et 0,03 respectivement). Un nombre moins élevé de patients des groupes EG et EGNS a nécessité des blocs nerveux supplémentaires et/ou une anesthésie générale. Après l’opération, les hématomes et douleurs axillaires ont été plus fréquemment observés dans le groupe NS.ConclusionCette étude démontre que l’échoguidage, avec ou sans neurostimulation concomitante, améliore de façon significative le taux de succès du bloc du plexus brachial par approche axillaire.

Ultrasound Guidance Improves the Success of Sciatic Nerve Block at the Popliteal Fossa

Background and Objectives: Real time ultrasound guidance is a recent development in the area of peripheral nerve blockade. There are limited data from prospective randomized trials comparing its efficacy to that of traditional nerve localization techniques. In the present study, we tested the hypothesis that ultrasound guidance improves the success rate of sciatic nerve block at the popliteal fossa when compared with a nerve stimulator‐guided technique. Methods: After Institutional Research Ethics Board approval and informed consent, 74 patients undergoing elective major foot or ankle surgery were randomly assigned to receive a sciatic nerve block at the popliteal fossa guided by either ultrasonography (group US, transverse view, needle in plane approach above the sciatic nerve bifurcation), or nerve stimulation (group NS, single injection, 10 cm proximal to the knee crease). A standardized local anesthetic admixture (15 mL of 2% lidocaine with 1:200,000 epinephrine and 15 mL of 0.5% bupivacaine) was used. Sensory and motor function was assessed by a blinded observer at predetermined intervals for up to 1 hour. Block success was defined as a loss of sensation to pinprick within 30 minutes in the distribution of both tibial and common peroneal nerves. Results: Group US had a significantly higher block success rate than group NS (89.2% vs. 60.6%, P = .005), while the procedure time was similar. Conclusions: Ultrasound guidance enhances the quality of popliteal sciatic nerve block compared with single injection, nerve stimulator‐guided block using either a tibial or peroneal endpoint. Ultrasound guidance resulted in higher success, faster onset, and progression of sensorimotor block, without an increase in block procedure time, or complications.

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.

Transversus abdominis plane block: a systematic review.

Ultrasound guidance has led a surge of interest in transversus abdominis plane (TAP) block for postoperative analgesia following abdominal surgery. Despite or because of the numerous descriptive applications and techniques that have recently populated the literature, results of comparative studies for TAP block have been inconsistent. This systematic review pragmatically addresses many unanswered questions, specifically the following: what are the effects of surgical procedure, block dose, block technique, and block timing on TAP block analgesia? Eighteen intermediate- to good-quality randomized trials that included diverse surgical procedures were identified. Improved analgesia was noted in patients undergoing laparotomy for colorectal surgery, laparoscopic cholecystectomy, and open and laparoscopic appendectomy. There was a trend toward superior analgesic outcomes when 15 mL of local anesthetic or more was used per side compared with lesser volumes. All 5 trials investigating TAP block performed in the triangle of Petit and 7 of 12 trials performed along the midaxillary line demonstrated some analgesic advantages. Eight of 9 trials using preincisional TAP block and 4 of 9 with postincisional block revealed better analgesic outcomes. Although the majority of trials reviewed suggest superior early pain control, we were unable to definitively identify the surgical procedures, dosing, techniques, and timing that provide optimal analgesia following TAP block. This review suggests that our understanding of the TAP block and its role in contemporary practice remains limited.

Early but No Long-term Benefit of Regional Compared with General Anesthesia for Ambulatory Hand Surgery

Background:The purpose of this study was to determine whether either regional anesthesia (RA) or general anesthesia (GA) provided the best analgesia with the fewest adverse effects up to 2 weeks after ambulatory hand surgery. Methods:Patients undergoing ambulatory hand surgery were randomly assigned to RA (axillary brachial plexus block; n = 50) or GA (n = 50). Before surgery, all patients rated their hand pain (visual analog scale) and pain-related disability (Pain-Disability Index). After surgery, eligibility for bypassing the postanesthesia care unit (“fast track”) was determined, and pain, adverse effects, and home-readiness scores were measured. On postoperative days 1, 7, and 14, patients documented their pain, opioid consumption, adverse effects, Pain-Disability Index, and satisfaction. Results:More RA patients were fast-track eligible (P < 0.001), whereas duration of stay in the postanesthesia care unit was shorter in the RA group (P < 0.001). Time to first analgesic request was longer in the RA group (P < 0.001), and opioid consumption was reduced before discharge (P < 0.001). In the RA group, the pain ratings measured at 30, 60, 90, and 120 min after surgery were lower (P < 0.001), and patients spent less time in the hospital after surgery (P < 0.001). More GA patients experienced nausea/vomiting during recovery in the hospital (P < 0.05). However, on postoperative days 1, 7, and 14, there were no differences in pain, opioid consumption, adverse effects, Pain-Disability Index, or satisfaction. Conclusions:Despite significant reduction in pain before discharge from the hospital after ambulatory hand surgery, single-shot axillary brachial plexus block does not reduce pain at home on postoperative day 1 or up to 14 days after surgery when compared with GA. However, RA does provide other significant early benefits, including reduction in nausea and faster discharge from the hospital.

An ultrasonographic and histological study of intraneural injection and electrical stimulation in pigs.

BACKGROUND: In this study we evaluated the minimum stimulating current associated with intraneural needle placement and sonographic appearance of intraneural injection. METHODS: We inserted a needle 2 cm inside 28 pig nerves (brachial plexus in vivo), recorded the minimum current to elicit a motor response, and injected dye (5 mL) under ultrasound (US) imaging. RESULTS: The minimum current to elicit a motor response was 0.43 mA (range: 0.12–1.8 mA). Nerve expansion was visualized by US in 24 of 28 nerves. Histology revealed penetration of the epineurium in these same 24 nerves. There was no evidence of dysplasia within the fascicle of any nerve. CONCLUSIONS: US may prove useful to detect intraneural injection, whereas a motor response above 0.5 mA may not exclude intraneural needle placement. The correlation between intraneural injection and neurological dysfunction remains unclear.

Does regional anaesthesia improve outcome after total hip arthroplasty? A systematic review

Total hip arthroplasty (THA) is amenable to a variety of regional anaesthesia (RA) techniques that may improve patient outcome. We sought to answer whether RA decreased mortality, cardiovascular morbidity, deep venous thrombosis (DVT) and pulmonary embolism (PE), blood loss, duration of surgery, pain, opioid-related adverse effects, cognitive defects, and length of stay. We also questioned whether RA improved rehabilitation. To do so, we performed a systematic review of the contemporary literature to compare general anaesthesia (GA) and RA and also systemic and regional analgesia for THA. To reflect contemporary surgical and anaesthetic practice, only randomized controlled trials (RCTs) from 1990 onward were included. We identified 18 studies involving 1239 patients. Only two of the 18 trials were of Level I quality. There is insufficient evidence from RCTs alone to conclude if anaesthetic technique influenced mortality, cardiovascular morbidity, or the incidence of DVT and PE when using thromboprophylaxis. Blood loss may be reduced in patients receiving RA rather than GA for THA. Our review suggests that there is no difference in duration of surgery in patients who receive GA or RA. Compared with systemic analgesia, regional analgesia can reduce postoperative pain, morphine consumption, and nausea and vomiting. Length of stay is not reduced and rehabilitation does not appear to be facilitated by RA or analgesia for THA.

Artifacts and pitfall errors associated with ultrasound-guided regional anesthesia. Part II: a pictorial approach to understanding and avoidance.

t o l he use of real-time ultrasound guidance in regional anesthesia is growing in popularity. Parmount to the successful and safe use of ultrasound s the appreciation and accurate interpretation of ommon ultrasound-generated artifacts. An artifact s any perceived distortion, error, or addition caused y the instrument of observation (signal procesor).1 Imaging artifacts can be considered display henomena, and, therefore, can potentially compliate the planned procedure. There are 4 generic ategories of imaging artifacts:2 (1) Acoustic: error n presentation of ultrasound information; (2) Antomic: error in interpretation (often called “pitfall” rror); (3) Optical illusion: error in perception; and 4) Other: electrical noise. This article builds on the fundamental principles f ultrasound physics that are discussed in Part I of his article.3 The objective of this article is to decribe and illustrate many of the acoustic and anaomic artifacts commonly encountered by the reional anesthesiologist. In the process, we will offer nderlying physical explanations and describe pracical tips on how to negotiate these often misleading henomena.

Eight Ball, Corner Pocket: The Optimal Needle Position for Ultrasound-Guided Supraclavicular Block

of surface landmarks for the lateral popliteal sciatic-nerve block depends upon the accurate location of the groove between the lateral border of the vastus lateralis muscle and tendon of the biceps femoris muscle.1-3 This process can be challenging, particularly in the muscular or obese patient, and maneuvers designed to accentuate the groove necessitate mobilization of what might be a traumatized limb. We propose the fibula as a fixed landmark that is easily palpable in all patients, regardless of body habitus, and that, more significantly, does not require limb mobilization for identification. With the patient in a supine position, the ipsilateral lower limb is placed in the anatomic position with the foot at a 90° angle to the horizontal plane of the table. The head of the fibula is identified, and a line parallel to the long axis of the fibula and horizontal to the plane of the table is traced proximally at this level. A second line is traced laterally from the upper edge of the patella. The needle insertion site is defined as the intersection of these two lines (Fig 1). The stimulating needle is advanced in the same direction and the block performed in the same manner as previously described.1,2 This minor modification to the classically described approach of lateral popliteal sciatic-nerve block is a simple technique that relies on clear, easy identifiable landmarks. The need to mobilize the potentially traumatized limb is eliminated, making block performance easier for patient and physician alike.