Robert S. Weller

The American Society of Regional Anesthesia and Pain Medicine and the European Society of Regional Anaesthesia and Pain Therapy Joint Committee Recommendations for Education and Training in Ultrasound-guided Regional Anesthesia

Ultrasound-guided regional anesthesia (UGRA) is a growing area of both clinical and research interest. The following document contains the work produced by a joint committee from ASRA and the European Society of Regional Anesthesia and Pain Therapy. This joint committee was established to recommend to members and institutions the scope of practice, the teaching curriculum, and the options for implementing the medical practice of UGRA. This document specifically defines the following: 1. 10 common tasks used when performing an ultrasound-guided nerve block, 2. The core competencies and skill sets associated with UGRA, 3. A training practice pathway for postgraduate anesthesiologists, and 4. A residency-based training pathway. In both the residency and postgraduate pathways, training, competency, and proficiency requirements include both didactic and experiential components. The Joint Committee recommends that the decision to grant UGRA privileges be based at the individual institution level. Each institution that conducts UGRA is encouraged to support a productive quality improvement process.

Coronary artery stents: II. Perioperative considerations and management.

The management of patients with coronary artery stents during the perioperative period is one of the most important patient safety issues clinicians confront. Perioperative stent thrombosis is a life-threatening complication for patients with either bare-metal or drug-eluting stents. Noncardiac surgery appears to increase the risk of stent thrombosis, myocardial infarction, and death, particularly when patients undergo surgery early after stent implantation. The incidence of complications is further increased when dual-antiplatelet therapy is discontinued preoperatively. It is generally agreed that aspirin must be continued throughout the perioperative period, except in circumstances when the risk of bleeding significantly outweighs the benefit of continued anticoagulation, such as procedures performed in a closed space. We present considerations for regional anesthesia, as well as postoperative recommendations as the occurrence of perioperative stent thrombosis appears to be greatest during this period. Immediate percutaneous coronary intervention is the definitive treatment for perioperative stent thrombosis, and 24-h access to an interventional cardiology suite should be readily available. Algorithms for perioperative management of patients with bare-metal and drug-eluting stents are proposed.

Activation of the Bezold-Jarisch reflex in the sitting position for shoulder arthroscopy using interscalene block.

A retrospective analysis of 116 patients who underwent shoulder arthroscopy in the sitting position with interscalene block (ISB) revealed 20 patients who experienced potentially dangerous vasovagal events characterized by sudden severe hypotension and bradycardia (Group 1).The event occurred 61 +/- 18 min after the block placement. Ninety-six patients (Group 2) did not experience a vasovagal event. Of the patients in Group 2, 18 received beta-adrenergic blockers for increasing heart rate and/or arterial blood pressure (Group 2B) while 78 did not (Group 2A). The number receiving beta-adrenergic blockers was significantly greater than in Group 1 (18/96 vs 0/20, P < 0.05). There were no significant demographic or baseline hemodynamic differences between groups, but the beta-adrenergic blocker and vagal groups showed significantly greater intraoperative peak heart rates (P < 0.05). All patients received epinephrine in their local anesthetic for ISB, incision sites, and articular irrigating solution. Total and weight-corrected epinephrine doses differed significantly between groups (lowest in Group 2A, P < 0.01). Activation of the Bezold-Jarisch reflex, induced by increased circulating epinephrine levels and the sitting position, is the postulated mechanism. (Anesth Analg 1995;80:1158-62)

Ibuprofen provides longer lasting analgesia than fentanyl after laparoscopic surgery

The authors compared the analgesic efficacy of one dose of oral ibuprofen with that of intravenously administered fentanyl for relief of pain after outpatient laparoscopic surgery. Thirty healthy female patients received either 800 mg of oral ibuprofen preoperatively or 75 micrograms of intravenous fentanyl intraoperatively plus respective intravenous or oral placebos in a randomized, double-blind manner. Patients recorded their degree of pain and nausea in the recovery room, in the same-day surgery stepdown unit, during the ride home, and upon arrival at home. The postanesthesia care nurse recorded the amount of fentanyl and droperidol needed to treat pain and nausea in the recovery room. Patients who received ibuprofen were more comfortable in the stepdown unit (P less than 0.05) and after arrival home (P less than 0.05) than those in the fentanyl group. Additionally, patients who received ibuprofen had lower nausea scores in the step-down unit (P less than 0.05); this may have been related to the lower total fentanyl dose in these patients. The authors conclude that ibuprofen may be a useful alternative to fentanyl for providing postoperative analgesia for outpatient surgery.

Local Anesthetic-Induced Cardiac Toxicity: A Survey of Contemporary Practice Strategies Among Academic Anesthesiology Departments

Though new local anesthetics (LA), effective test-dosing, and new regional anesthetic techniques may have improved the safety of regional anesthesia, the optimal management plan for LA-induced cardiac toxicity remains uncertain. Accordingly, we evaluated current approaches to LA cardiotoxicity among academic anesthesiology departments in the United States. A 19-question survey regarding regional anesthesia practices and approaches to LA cardiac toxicity was sent to the 135 academic anesthesiology departments listed by the Society of Academic Anesthesiology Chairs-Association of Anesthesiology Program Directors. Ninety-one anonymously completed questionnaires were returned, at a response rate of 67%. The respondents were categorized into groups according to the number of peripheral nerve blocks (PNBs) performed each month: >70 PNBs (38%), 51–70 PNBs (13%), 31–50 PNBs (20%), 11–30 PNBs (23%), and <10 PNBs (6%). Anesthesia practices administering >70 PNBs were 1.7-times more likely to use ropivacaine (NS), 3.9-times more likely to consider lipid emulsion infusions for resuscitation (P = 0.008), and equally as likely to have an established plan for use of invasive mechanical cardiopulmonary support in the event of LA cardiotoxicity (NS) than low-PNB volume centers. We conclude that there are differences in the management and preparedness for treatment of LA toxicity among institutions, but the safety implications of these differences are undetermined.

Ultrasound-guided interscalene needle placement produces successful anesthesia regardless of motor stimulation above or below 0.5 mA.

BACKGROUND:We quantified the motor response after ultrasound (U-S)-guided needle placement for interscalene block (ISB). We then compared block characteristics based on motor response above or below 0.5 mA. METHODS:Sixty-one patients scheduled for ambulatory shoulder surgery under ISB and general anesthesia were included in this prospective, observational study. Preoperatively, an insulated needle was positioned by U-S in the interscalene groove. The lowest current producing motor response was determined, and 30 mL 0.5% bupivacaine with epinephrine was injected. Motor and sensory block were tested in the upper trunk distribution for 15 min until general anesthesia was induced. Postoperatively, the success of upper trunk block, pain score in the postanesthesia care unit and block duration, and analgesic tablet consumption overnight were recorded. Patients were divided a priori into Group A (current ≤0.5 mA) and Group B (current >0.5 mA), and results were compared between groups. RESULTS:The observed current range was 0.14–1.7 mA, with current ≤0.5 mA in 42% of patients (Group A). All patients had complete sensorimotor upper trunk block and none required narcotics in the postanesthesia care unit. Block duration (both groups: 17.8 ± 4.9 h, mean ± sd) and home analgesic use were equivalent. Sensory block onset was equivalent between groups, but incomplete motor block at 15 min was more likely in Group B: 37% vs 12% in Group A (P = 0.03). CONCLUSION:During U-S-guided ISB using nerve stimulation, the observed motor response below or above 0.5 mA had no impact on success or duration of upper trunk block.

Decreasing the local anesthetic volume from 20 to 10 mL for ultrasound-guided interscalene block at the cricoid level does not reduce the incidence of hemidiaphragmatic paresis.

Background and Objectives: This prospective, randomized, double-blind study was designed to determine whether reduction in volume from 20 to 10 mL of ropivacaine 0.5% for ultrasound-guided interscalene block might decrease the incidence of diaphragmatic paresis and preserve pulmonary function. Method: Thirty patients scheduled for arthroscopic shoulder surgery were randomized to receive either 10 or 20 mL of ropivacaine 0.5% for interscalene block at the level of the cricoid cartilage. General anesthesia was administered for surgery, and the surgeon infiltrated lidocaine at the port sites. Hemidiaphragmatic excursion and pulmonary function tests were measured before block, 15 mins after block, and at the time of discharge from recovery room. Onset and duration of sensory dermatomal spread, motor block, pain scores, and analgesic consumption were recorded. Results: Hemidiaphragmatic paresis occurred 15 mins after block performance in 14 of 15 patients in each group. At postanesthesia care unit discharge, 13 of 15 patients in each group continued to demonstrate hemidiaphragmatic paresis. Significant reduction of spirometric values (forced vital capacity, forced expiratory volume at 1 sec, and peak expiratory flow) occurred to a similar degree in both groups after block. Sensory dermatomal spread, motor block, pain scores, and analgesic consumption were not significantly different between groups. Conclusions: Decreasing the volume for interscalene block from 20 to 10 mL did not reduce the incidence of hemidiaphragmatic paresis or impairment in pulmonary function, which persisted at discharge from recovery room. No significant differences in quality or duration of analgesia were observed.

Ultrasound-guided obturator nerve block: an interfascial injection approach without nerve stimulation.

Background and Objectives: For knee surgery, obturator nerve block (ONB) has been shown to enhance postoperative analgesia provided by femoral block. Current techniques for obturator block use surface landmarks or ultrasound guidance (USG) with nerve stimulation. This preliminary observational study evaluated the success of an ultrasound-guided ONB without the additional use of nerve stimulation. Methods: Thirty patients scheduled for knee surgery under general anesthesia with nerve block for postoperative analgesia had ONB performed using USG and injection of 10 mL 0.5% ropivacaine with epinephrine. Half of the ropivacaine was injected between the pectineus and adductor brevis muscles, and half between the adductor brevis and adductor magnus muscles. The strength of thigh adduction was measured at 5, 10, and 15 mins after injection, and 50% strength reduction at 15 mins indicated a successful block. Results: All patients showed reduction of strength, and 28 of 30 or 93% met the criteria for successful block with mean strength reduction of 82.2% (SD, 21.6%) at 15 mins. Blocks were completed in 122 secs (SD, 33 secs). Conclusions: Obturator nerve block using USG to achieve interfascial injection without nerve stimulation had success similar to that reported in studies using nerve stimulation.

Flumazenil antagonism of midazolam-induced ventilatory depression.

Flumazenil, a benzodiazepine antagonist, reliably reverses midazolam-induced sedation; however, its effect on respiratory depression has not been established completely. Twelve healthy volunteers received sufficient midazolam (0.13 +/- 0.01 mg.kg-1 mean +/- SE) to render them unresponsive to verbal command; they then received flumazenil 1.0 mg or placebo (flumazenil vehicle) in a randomized, double-blind fashion. Ventilatory drive was measured before and after administration of midazolam, as well as 3, 30, 60, and 120 min after administration of flumazenil or placebo. Seven to 30 days later, the study was repeated, with subjects receiving placebo or flumazenil (whichever they had not received during their first trial). Midazolam caused significant decreases in the slope of the CO2 response (-29 +/- 5%; P less than 0.005); minute ventilation (VE) at end-tidal CO2 tension (PETCO2) = 46 mmHg (-28 +/- 4%; P less than 0.001), and tidal volume at PETCO2 = 46 mmHg (-44 +/- 4%; P less than 0.005). Three minutes after intravenous administration of flumazenil 1.0 mg, VE46 and tidal volume increased to 108 +/- 6% and 105 +/- 6%, respectively, of their premidazolam values; at the same time after administration of placebo, VE46 and tidal volume remained significantly depressed (between groups, P less than 0.005 for each variable). Thirty minutes later, these variables did not differ between groups, probably because the effects of flumazenil and midazolam were diminishing.(ABSTRACT TRUNCATED AT 250 WORDS)

Femoral nerve block with selective tibial nerve block provides effective analgesia without foot drop after total knee arthroplasty: a prospective, randomized, observer-blinded study.

BACKGROUND: Sciatic nerve block when combined with femoral nerve block for total knee arthroplasty may provide superior analgesia but can produce footdrop, which may mask surgically induced peroneal nerve injury. In this prospective, randomized, observer-blinded study, we evaluated whether performing a selective tibial nerve block in the popliteal fossa would avoid complete peroneal motor block. METHODS: Eighty patients scheduled for primary total knee arthroplasty were randomized to receive either a tibial nerve block in the popliteal fossa or a sciatic nerve block proximal to its bifurcation in combination with femoral nerve block as part of a multimodal analgesia regimen. Local anesthetic solution of sufficient volume to encircle the target nerve was administered for the block, up to a maximum of 20 mL. General anesthesia was administered for surgery. After emergence from anesthesia, in the recovery room, the presence or absence of peroneal sensory and motor block was noted. Pain scores and opioid consumption were recorded for 24 hours after surgery. RESULTS: The tibial nerve block and sciatic nerve block were performed 1.7 cm (99% CI, 1.3 to 2.1) and 9.4 cm (99% CI, 8.3 to 10.5) proximal to the popliteal crease, respectively (99% CI for difference between means: 6.4 to 9.0; P < 0.001). A lower volume of ropivacaine 0.5% was used for the tibial nerve block, 8.7 mL (99% CI, 7.9 to 9.4) versus 15.2 mL (99% CI, 14.9 to 15.5), respectively (99% CI for difference between means, 5.6 to 7.3; P < 0.001). No patient receiving a tibial nerve block developed complete peroneal motor block compared to 82.5% of patients with sciatic nerve block (P < 0.001). There were no significant differences in the pain scores and opioid consumption between the groups. CONCLUSIONS: Tibial nerve block performed in the popliteal fossa in close proximity to the popliteal crease avoided complete peroneal motor block and provided similar postoperative analgesia compared to sciatic nerve block when combined with femoral nerve block for patients undergoing total knee arthroplasty.