Symptoms Of Local Anesthetic Toxicity Research Articles

Three-dimensional printed personalised digital guide plate for greater palatine block in trigeminal neuralgia

The nerve block is a safe and effective method to theat trigeminal neuralgia (TN). In terms of the V2 trigeminal neuralgia, the most difficult procedure in nerve block is accurate and fast greater palatine foramen (GPF) insertion. In this study, we developed a new technique using a personalised digital tooth-supported guide plate to increase insertion accuracy and success rates and reduce the pain of patients during injection. A total of 18 patients with TN (11 female and 7 male) were enrolled and treated between September 2020 and June 2022. Before injection, the guide plate was designed via Mimics three-dimensional (3D) reconstruction technology and printed via 3D printer. Then, all patients underwent maxillary nerve block with a guide plate for each injection. In this study, placement of all guide plates was completed within one minute and all punctures were successful the first time. The depth of the injection needle was over 2.5 cm in all cases and the guide plate was stability-supported by the maxillary teeth. The various pain scores had an obvious improvement. No patients presented symptoms of local anaesthetic toxicity or onset of new neurological sequelae. Using this new technology, we can significantly reduce the difficulty of GPF insertion and decrease patient pain during injection. The enhanced success rate of nerve block can achieve better therapeutic effect. For surgeons, personalised digital tooth-supported guide plates make the operation easier, especially for novice surgeons.

Systemic Ropivacaine Concentrations Following Local Infiltration Analgesia and Femoral Nerve Block in Older Patients Undergoing Total Knee Arthroplasty.

The study examined the pharmacokinetic profile of fixed formulation mixtures comprising 225 mg of ropivacaine for local infiltration analgesia with or without epinephrine, and femoral nerve block in older patients presenting for orthopedic surgery and explored potential influences of block type, age, and body weight on this profile. Twenty four patients scheduled for total knee arthroplasty were randomly assigned to three groups: femoral nerve block, local infiltration analgesia with epinephrine and local infiltration analgesia without epinephrine. Blood samples were collected at 10, 30, 60, and 120 min following the block and total plasma concentrations of ropivacaine were quantified by high performance liquid chromatography. The mean individual peak total plasma concentrations of ropivacaine in local infiltration analgesia with and without epinephrine, and femoral nerve block group were 0.334, 0.490 and 0.545 μg mL-1 (p = 0.16). Local infiltration with epinephrine group had significantly lower plasma ropivacaine concentrations at 30, 60 and 120 minutes. The plasma ropivacaine concentrations exceeded 2.2 μg mL-1 in one patient. Age, but not body weight, had a moderate correlation with peak plasma ropivacaine concentration (r = 0.37, p = 0.08). Administration of a fixed 225 mg dose of ropivacaine for local infiltration analgesia with epinephrine and femoral nerve block results in plasma ropivacaine concentrations below the toxicity threshold, indicating their safety. The use of local infiltration analgesia with epinephrine provides a greater safety margin, as local infiltration analgesia without epinephrine may lead to ropivacaine concentrations associated with symptoms of local anesthetic toxicity.

A Randomized Comparison of Plasma Levobupivacaine Concentrations Following Thoracic Epidural Analgesia and Subpleural Paravertebral Analgesia in Open Thoracic Surgery.

Background: The aim of this study was to compare plasma levobupivacaine concentrations in thoracic epidural and subpleural paravertebral analgesia. Methods: Forty-four patients indicated for open lung resection had an epidural catheter inserted preoperatively or a subpleural catheter surgically. A bolus of 0.25% levobupivacaine at a dosage of 0.5 mg × kg−1 was given after the thoracotomy closure. Plasma levobupivacaine level at 30 min was the primary outcome. Pharmacokinetic modeling was performed subsequently. Secondary outcomes included the quality of analgesia, complications, and patients’mobility. Results: Plasma concentrations were similar 30 min after application—0.389 mg × L−1 in the epidural and 0.318 mg × L−1 in the subpleural group (p = 0.33) and lower in the subpleural group at 120 min (p = 0.03). The areas under the curve but not maximum concentrations were lower in the subpleural group. The time to reach maximum plasma level was similar in both groups—27.6 vs. 24.2 min. No clinical symptoms of local anesthetic toxicity were recorded. Conclusions: Levobupivacaine systemic concentrations were low in both groups without the symptoms of toxicity. This dosage should be safe for postoperative analgesia after thoracotomy.

Serum ropivacaine levels after local infiltration analgesia during total knee arthroplasty with and without adductor canal block.

A common analgesic technique for total knee arthroplasty (TKA) is to inject local anesthetic into the periarticular tissue during surgery, known as local infiltration analgesia (LIA). Since the solution used typically contains a large amount of local anesthetic, concerns arise about exceeding the maximum dosage when adding a peripheral nerve block. Little research exists that addresses serum ropivacaine concentrations following LIA combined with peripheral nerve block. We hypothesized that after combining LIA and adductor canal blockade (ACB), serum ropivacaine concentrations would remain below levels associated with local anesthetic toxicity. This was a prospective observational study that included 14 subjects undergoing TKA with intraoperative LIA containing 270 mg ropivacaine with epinephrine. Patients weighing less than 80 kg were excluded due to standardized dosing by our pharmacy. Seven patients were assigned consecutively to receive LIA alone (Group LIA) and seven were assigned to receive LIA plus ACB with 100 mg ropivacaine with epinephrine (Group LIA+ACB). Venous serum ropivacaine concentrations were measured over 24 hours. Peak serum concentrations (Cmax) in Group LIA ranged from 0.23 to 0.75 µg/mL and occurred at times from 4 to 24 hours. Cmax in Group LIA+ACB ranged from 0.46 to 1.00 µg/mL and occurred at times from 4 to 8 hours. No participants demonstrated signs or symptoms of local anesthetic toxicity. Total serum concentration of ropivacaine after LIA using 270 mg ropivacaine with and without an additional 100 mg perineural ropivacaine remained well below the toxicity threshold of 3.0 µg/mL at all time points. Additional studies are needed to ascertain the safety of combining LIA with peripheral nerve blockade.

Thoracic paravertebral blockade in breast surgery: Is pneumothorax an appreciable concern? A review of over 1000 cases.

There has been a substantial increase in ambulatory day-case breast surgery in recent decades. This has been largely due to improvements in anesthetic procedures and pre-emptive analgesia. Thoracic paravertebral blockade (TPVB) is increasing in popularity, though concerns over iatrogenic injury remain, especially pneumothorax. The purpose of this study was to conduct a review of the incidence of pneumothorax following TPVB prior to breast surgery. Data from of a consecutive series of patients having TPVB prior to breast surgery between 2009 and 2014 were reviewed. TPVB were used prior to unilateral and bilateral procedures. Medical records were retrospectively assessed for any complication including pleural punctures, pneumothorax, hypotension, bradycardia as well as signs and symptoms of local anesthetic toxicity. 1152 patients underwent a total of 1322 TPVB injections (982 unilateral and 340 bilateral). Clinically significant hypotension and/or bradycardia occurred in 26 patients (2.2%). Two patients (0.17%) had a suspected toxicity from the local anesthetic. Incidence of pleural puncture was 0.6% (n=9) and pneumothorax 0.26% (n=3). All pneumothoraxes were managed conservatively. There was no statistical difference in complication rates in those that had unilateral vs bilateral TPVB or those that had ultrasound guidance (P=.09). Good pre-emptive analgesia is pertinent to prevent acute postoperative pain. TPVB have been shown to be successful in reducing rescue analgesia. This study shows TPVB is a well-tolerated procedure, with a low associated incidence of iatrogenic injury and complication.

Home peripheral nerve catheters: the first 24 months of experience at a children's hospital.

ContextHome peripheral nerve catheters (PNCs) have become common practice for adult patients after major orthopedic surgery. However, use in pediatric patients is a recent application.ObjectivesThe purpose of this study was to review the demographics and outcomes of pediatric patients receiving a PNC at our institution.MethodsThis retrospective study included patients from October 2012 through October 2014 undergoing orthopedic procedures with a PNC placed for postoperative pain management.ResultsA total of 118 patients aged 3.2–25.3 years were identified. The types of catheters included femoral (80.5%), interscalene (11.9%), sciatic (5.9%), and supraclavicular (1.7%). The majority of patients were discharged to home on the day of surgery (77.1%). In the postanesthetic care unit, the average pain score was 2.5, the incidence of nausea/emesis was 5.9%, and the need for opioid administration was 50.8%. There were no major complications. Minor complications included a 7.6% rate of early catheter removal with 5.9% of those due to catheter leakage and an unsecure dressing. There was one case of metallic taste in the mouth without other symptoms of local anesthetic toxicity that resolved without further complication.ConclusionThe implementation of a home PNC program in pediatric patients at our institution has been highly successful with a high rate of ambulatory catheters, low pain scores, low rates of nausea and vomiting, and no serious complications. Minor complications included leaking of the catheter and early discontinuation of the catheter.

The effect of continuous wound infusion of ropivacaine on postoperative pain after median sternotomy and mediastinal drain in children.

Postoperative pain after median sternotomy is usually treated with i.v. opioids. We hypothesized that continuous wound infusion of ropivacaine decreases postoperative morphine consumption and improves analgesia in children who undergo cardiac surgery. This randomized, double-blind study comprised 49 children aged 1-9 years who underwent atrial septal defect (ASD) closure. Patients received continuous local anesthetic wound infiltration either with 0.2% ropivacaine, 0.3-0.4 mg·kg(-1) ·h(-1) (Group R) or with saline (Group C). Rescue morphine consumption, Objective Pain Scale (OPS), time to mobilization, time to enteral food intake, and time to discharge were recorded. There were no statistically significant differences in morphine consumption at 24, 48, and 72 h postsurgery between R and C groups. There was a weak evidence for a difference in the time to the first morphine administration after tracheal extubation to be longer for Group R than Group C (186.2 vs 81.0 min; 95% CI (-236.5, 26.2), P = 0.114). The incidence of nausea and vomiting were comparable between the groups. No signs or symptoms of local anesthetic toxicity were registered. Contrary to our hypothesis, continuous ropivacaine wound infusion did not reduce morphine consumption, pain score values, or nausea and vomiting in children who underwent ASD closure with median sternotomy and mediastinal drain.

Ultrasound-Guided Transversus Abdominis Plane Block for Analgesia in Laparoscopic Cholecystectomy: A Systematic Review and Meta-Analysis

Objectives: To evaluate the analgesic efficacy of ultrasound-guided transversus abdominis plane (TAP) block for patients undergoing laparoscopic cholecystectomy (LC). Materials and Methods: A systematic literature search was conducted to identify randomized controlled trials that compared ultrasound-guided TAP block with control for analgesia in adult patients undergoing LC. The original data were pooled for the meta-analysis using Review Manager 5. The main outcomes included postoperative pain intensity, opioid consumption, and adverse events. Out of a total of 77 trials, 7 were included. Results: Compared with control, ultrasound-guided TAP block reduced the following: (1) postoperative pain intensity (visual analog scale: 0-10) both at rest and on movement at 0, 2, 4, 8, and 24 h (at rest: mean difference, MD_{0 h} = -2.19, 95% confidence interval, CI: -3.46 to -0.91, p = 0.0008; on movement: MD_{0 h} = -2.67, 95% CI: -3.86 to -1.48, p < 0.0001); (2) intraoperative fentanyl consumption (MD = -27.85 µg, 95% CI: -44.91 to -10.79, p = 0.001), and (3) morphine consumption in the recovery room (MD = -1.57 mg, 95% CI: -3.0 to -0.14, p = 0.03) and 0-24 h postoperatively. Fewer patients required analgesics in the recovery room when receiving TAP blocks (risk ratio, RR = 0.35, 95% CI: 0.20 to 0.62, p = 0.0003). TAP blocks also reduced postoperative nausea and vomiting (RR = 0.48, 95% CI: 0.28 to 0.81, p = 0.006). None of the studies reported symptoms of local anesthetic toxicity. Conclusions: In this study, the ultrasound-guided TAP block was an effective strategy for analgesia in patients undergoing LC.

Plasma concentrations of ropivacaine following ultrasound-guided or nerve-stimulator-guided femoral nerve block: A prospective randomised study

ObjectiveOur aim was to establish a plasma concentration curve for ropivacaine following femoral nerve blockade and to ascertain whether the resulting plasma concentrations differ significantly depending on whether neurostimulation (NS) or ultrasound (US) guidance was used. MethodsSixteen male and female subjects aged 18 to 80 who were scheduled to undergo unilateral total knee replacement or anterior cruciate ligament reconstruction under general or spinal anaesthesia, and for whom a femoral nerve block was indicated for postoperative analgesia, were enrolled in this prospective, randomised study. Patients were randomised to undergo either US or NS-guidance femoral nerve blocks. All blocks were performed with 20mL of 5mg/mL ropivacaine. Blood samples were drawn before the nerve block and 20, 30, 40, 50, 60, 70, and 80minutes after the block. Plasma levels of ropivacaine were analysed by high performance liquid chromatography (HPLC). ResultsAll blocks were successful and no patient showed signs or symptoms of local anaesthetic toxicity. The plasma concentration of ropivacaine peaked at 30minutes in both arms. There was no significant difference in peak levels between US and NS-guidance (0.325±0.186 versus 0.356±0.106μg/mL). Cmax and tmax were very similar between groups (0.364±0.177 versus 0.344±0.127μg/mL, 33.75±15.06 versus 31.25±13.56min for US and NS, respectively). ConclusionPlasma concentrations of ropivacaine peak around 30minutes after a femoral nerve block regardless of the technique used. No significant difference was found between US- and NS-guidance.

Symptomatic Local Anaesthetic Toxicity and Plasma Ropivacaine Concentrations After Transversus Abdominis Plane Block for Caesarean Section

Background The transversus abdominis plane (TAP) block involves injecting a large volume of local anaesthetic between the muscles of the abdominal wall. Plasma concentrations of ropivacaine after gynaecological laparotomy are potentially high enough to result in systemic toxicity, and there are pharmacokinetic reasons why pregnancy may increase susceptibility to local anaesthetic toxicity. Methods Adult female patients (n=30) undergoing elective Caesarean section under spinal anaesthesia received bilateral ultrasound-guided TAP blocks after wound closure (2.5 mg kg−1 of ropivacaine diluted to 40 ml). Venous blood samples were collected at 10, 20, 30, 45, 60, 90, 120, 180 and 240 min following the block. Blood samples were assayed for total and free ropivacaine concentrations. Patients were assessed for symptoms of local anaesthetic toxicity. Results The mean [standard deviation ( sd )] peak total concentration of ropivacaine occurred at 30 min post-injection and was 1.82 (0.69) μg ml−1. The maximum detected concentration in any patient was 3.76 μg ml−1 (at 10 min post-injection). Three patients reported symptoms of mild neurotoxicity, and the mean ( sd ) peak levels were elevated in these patients, 2.70 (0.46) µg ml−1. Conclusions TAP blocks can result in elevated plasma ropivacaine concentrations in patients undergoing Caesarean section, which may be associated with neurotoxicity.

Ultrasound-Guided Trigeminal Nerve Block via the Pterygopalatine Fossa: An Effective Treatment for Trigeminal Neuralgia and Atypical Facial Pain

Background: Patients presenting with facial pain often have ineffective pain relief with medical therapy. Cases refractory to medical management are frequently treated with surgical or minimally invasive procedures with variable success rates. We report on the use of ultrasound-guided trigeminal nerve block via the pterygopalatine fossa in patients following refractory medical and surgical treatment. Objective: To present the immediate and long-term efficacy of ultrasound-guided injections of local anesthetic and steroids in the pterygopalatine fossa in patients with unilateral facial pain that failed pharmacological and surgical interventions. Setting: Academic pain management center. Design: Prospective case series. Methods: Fifteen patients were treated with ultrasound-guided trigeminal nerve block with local anesthetic and steroids placed into the pterygopalatine fossa. Results: All patients achieved complete sensory analgesia to pin prick in the distribution of the V2 branch of the trigeminal nerve and 80% (12 out of 15) achieved complete sensory analgesia in V1, V2, V3 distribution within 15 minutes of the injection. All patients reported pain relief within 5 minutes of the injection. The majority of patients maintained pain relief throughout the 15 month study period. No patients experienced symptoms of local anesthetic toxicity or onset of new neurological sequelae. Limitations: Prospective case series. Conclusion: We conclude that the use of ultrasound guidance for injectate delivery in the pterygopalatine fossa is a simple, free of radiation or magnetization, safe, and effective percutaneous procedure that provides sustained pain relief in trigeminal neuralgia or atypical facial pain patients who have failed previous medical interventions. Key words: Trigeminal nerve, ultrasound-guided, atypical facial pain, trigeminal neuralgia, tic douloureux.

Undetected intravascular injection during an ultrasound-guided axillary block

To the Editor, There is evidence that the use of ultrasound-guided regional anesthesia increases the efficacy of peripheral nerve blocks and improves safety while allowing administration of lower volumes of local anesthetics. Onset of the block is also faster, possibly because of visualization of the target nerve in real time and injection of local anesthetic closer to the nerve structures. It is logical to hypothesize that these advantages may reduce complications such as nerve injury and local anesthesia systemic toxicity (LAST). We report a case of LAST while performing an ultrasound-guided axillary block that was initially diagnosed by the presence of symptoms of local anesthetic toxicity. The patient provided consent for the publication of this case report. A 63-yr-old woman, American Society of Anesthesiologists’ physical status III, presented for a partial amputation of her right middle finger. An axillary block was recommended to her as an appropriate procedure. In the block room, standard monitoring was established, oxygen was applied by nasal prongs at 3 L min, and sedation was given with midazolam 1 mg iv. A 12 MHz linear ultrasound transducer (GE LOGIQ e, Wauwatosa, WI, USA) was placed at the deltopectoral groove. Next, the cross section of the axillary artery and the nerves surrounding it were identified. Under sterile conditions, 1% lidocaine 3 mL was applied to the skin and subcutaneous tissue. Using in-plane visualization, a 5-cm 21G EchoStim needle (Hakko Medical, Japan) connected to a nerve stimulator was directed to the six o’clock position of the artery. After confirmation with neurostimulation (wrist extension that disappeared at 0.3 mA) and negative aspiration, 5% dextrose 2 mL was injected and showed adequate spread around the radial nerve. After negative blood aspiration every 5 mL, 2% lidocaine was injected slowly with appropriate visualization of the spread of the injectate. When a volume of 13 mL was reached, the patient complained of numbness in her lips, a metallic taste in her mouth, and a sensation of fainting. At that point, the injection was interrupted, 100% oxygen via an Ambu face mask was given, and midazolam 2 mg iv was administered. The symptoms resolved after one minute, and the patient was transferred to the operating room where the scheduled procedure was completed. A tourniquet was used and an additional 2% lidocaine 3 mL was needed in the interdigital area. The patient was transferred to the recovery room hemodynamically stable. After surgery, the ultrasound video was reviewed in detail. In the analysis (Figure, Panel A), the needle appeared to be posterolateral to the axillary artery; however, upon closer inspection, the needle tip could be seen as indenting a small anechoic structure posterior to the artery. In the next frame and just before the appearance of LAST symptoms (Figure, Panel B), local anesthetic spread could be seen as a hypoechoic image posterior to the artery. A portion of local anesthetic was likely deposited into a small vessel characterized by the anechoic structure (Figure, Panel A), accounting for the patient’s symptoms. Intravascular injection occurred in spite of real-time visualization of the spread of the local anesthetic and absence of blood after needle aspiration. In this instance, enhancement artifacts posterior to the axillary artery may have been a confounding factor that limited visualization of the needle tip. C. M. Forero, MD D. Bayegan, MSc McMaster University, Hamilton, ON, Canada

Knowledge of Local Anesthetic Use Among Dermatologists

Local anesthesia is widely used in general dermatology practices. The onus is on the practitioner to have a sound knowledge of the pharmacology and dosing of any drug used, including local anesthesia. The dermatologist should also be aware of the signs, symptoms, and management of toxicity of local anesthetic use. The level of knowledge of dermatologists on this topic has not been previously assessed. To assess levels of knowledge of local anesthetic pharmacology, local anesthetic systemic toxicity (LAST), and the management of the latter of dermatologists. A survey designed to test knowledge of absolute dosing limits; calculation of patient-specific dosing using clinical vignettes; and awareness of the signs, symptoms, and management of LAST was distributed electronically to the membership of three professional dermatological organizations in the United Kingdom and Ireland, including one specialist dermatologic surgery group. Knowledge of local anesthetic use of dermatologists was comprehensive enough to practice safely, without necessarily being entirely accurate. Awareness of the signs and symptoms of local anesthetic toxicity was good, but awareness of the specific agent now recommended for the management of LAST in official guidelines was poor. Knowledge of local anesthetic dosing and toxicity is reasonable among dermatologists. Awareness of the guidelines for management of LAST, released by the American and Great Britain and Ireland associations of anesthetists, and in particular the use of lipid emulsion in this setting, could be improved.

Clinical experience of propofol in treatment of local anesthetic toxicity induced by sacral block

Objective To study the effect of propofol in treatment of local anesthetic toxicity induced by sacral block.Methods We retrospectively analyzed 22 cases(P)who had experienced local anesthetic toxicity induced by sacral block and received a treatment of propofol in our department from January 2002 to November 2010.Other 18 patients(D)who received diazepam therapy from September 1997 to May 2002 were taken as the control.Those data of HR,SpO2 and MAP which were measured immediately prior to,3,5,10 and 20 min after drug administration were analyzed.Results The symptoms of local anesthetic toxicity induced by sacral block were treated effectively in both groups.However,the time of toxic symptoms withdrawl (15±6)s and awakening(6±4)min were significantly shorter in group P(P＜0.01).Conclusions Local anesthetic toxicity induced by sacral block can be effectively treated,and toxic symptom quickly can be corrected by intravenous injection of propofol.Thus,it may become a promising treatment. Key words: Propofol; Sacral block; Toxic reaction; Local anesthetic

Topical anaesthesia of the upper airway following deliberate sulphuric acid ingestion

A 36-year-old man presented to our trauma centre with significant mucosal burns, following a deliberate sulphuric acid ingestion. Initially we noted his voice was hoarse; however, this quickly progressed to aphonia. We decided to intubate his trachea to secure the airway and allow surgical intervention. Given the risk of difficult laryngoscopy, we decided to perform an awake fibreoptic intubation. However, given that the patient had ingested a large volume of highly concentrated sulphuric acid an hour before presentation, we were uncertain how long it would take for tissue pH to normalise again. Lidocaine, an amide local anaesthetic with a pKa of 7.9, may not be effective in such an acidic environment. We were also concerned that the airway burns could increase the risk of local anaesthetic systemic toxicity, as a result of an increased rate of absorption [1]. We transferred the patient to the operating theatre and undertook anaesthesia with noninvasive monitoring, intravenous lipid available and our surgical colleagues present. We achieved topical anaesthesia with 1 ml co-phenylcaine spray (5% lidocaine and phenylephrine) to one nostril and 10 ml lidocaine 2% to the pharynx using a Mucosal Atomisation Device (MADgic®, Wolfe Tory Medical, Utah, USA). We anaesthetised the supra and infraglottic areas with 2 ml lidocaine 4% via a cut epidural catheter. The patient did show signs of discomfort during application of the local anaesthetic. We then performed an uncomplicated upper airway endoscopy via the nostril without any discomfort or gag reflex. We observed extensive mucosal burns and swelling of the epiglottis and false vocal cords. Before topical anaesthesia of the glottic area, we noted that the vocal cords were non-mobile and in the abducted position. The patient did not cough and seemed comfortable during passage of a 6.5-mm reinforced tracheal tube through the glottis. The total lidocaine dose of 330 mg (approximately 4 mg.kg−1) did not lead to any symptoms of local anaesthetic toxicity. Over the next two days, the patient went on to have extensive surgery including a tracheostomy, oesophagogastrectomy, Whipple’s procedure with complete pancreatectomy and splenectomy. He has now been discharged from critical care and is awaiting further procedures for his laryngeal injuries. Acidic upper airway and gastrointestinal burns can have catastrophic consequences that need to be addressed in a timely fashion to avoid serious morbidity and mortality [2, 3]. This case highlights the plausibility and safety of topical airway anaesthesia and fibreoptic intubation in such caustic burns.

Intraabdominal local anaesthetics for postoperative pain relief following abdominal hysterectomy: a randomized, double-blind, dose-finding study

Local anaesthetics administered intraabdominally have been found to reduce analgesic requirements postoperatively after hysterectomy. This study was designed to assess the optimal dose of local anaesthetics for best pain relief. Sixty patients undergoing abdominal hysterectomy were randomly divided into three groups to receive 10 ml h infusion of levobupivacaine intraabdominally postoperatively for 48 h in a double-blind manner: group L, 7.5 mg h; group M, 12.5 mg h and group H, 17.5 mg h. Pain intensity was measured using the numeric rating scale, ketobemidone consumption over 48 h was measured with a patient-controlled analgesia pump, recovery parameters, expiratory muscle strength, time to home readiness, plasma concentration of levobupivacaine and health-related quality of life were all measured at defined time points postoperatively. No differences were found between the active groups in pain intensity, recovery parameters or health-related quality of life. Pain intensity was maximal during 0-4 h and during coughing. Expiratory muscle strength decreased significantly during 0-4 h in all active groups, with no differences between the groups. Plasma concentration of levobupivacaine was below known toxic concentrations in humans, and no patient had symptoms of local anaesthetic toxicity. Health-related quality of life showed improved scores at 3 months after the operation compared with preoperative values, but no differences between the groups were found in any of the parameters. Satisfactory analgesia can be achieved with low doses of levobupivacaine administered intraabdominally, except during the early postoperative period. No advantages were seen in this study when higher doses of levobupivacaine were administered as a continuous infusion for postoperative pain relief.

Minimizing the Risk of Intravascular Injection during Ultrasound-guided Peripheral Nerve Blockade

To the Editor: —We read with interest the recently published case reports by Loubert et al. 1and Zetlaoui et al. 2regarding suspected inadvertent intravascular injection of local anesthetic (LA) and LA toxicity during ultrasound-guided axillary brachial plexus blockade. While ultrasound likely reduces the risk of accidental vascular puncture compared with “blind” peripheral nerve stimulation,3these two case reports demonstrate that the risk of intravascular injection persists despite ultrasound guidance.1,2In 2006 and 2007 at the Toronto Western Hospital, we performed 1,797 ultrasound-guided brachial plexus blocks without any sign or symptom of LA toxicity. Good fortune notwithstanding, there are several important principles that merit thoughtful consideration to improve detection of accidental intravascular injection and possibly prevent LA toxicity during ultrasound-guided peripheral nerve blockade. We believe that the most reliable feature during real-time ultrasound imaging indicative of intravascular injection is the failure to visualize a hypoechoic fluid bolus on the ultrasound monitor during and/or after injection of as little as 1 ml of injectate. Indeed, we customarily initiate LA injection with a 1-ml bolus to exclude intravascular or intraneural4,5needle tip placement before proceeding with 5-ml increments of injectate. Visualization of the needle tip does not preclude intravascular injection per se ; it is the real-time observation of hypoechoic fluid causing tissue dispersion that most consistently excludes intravascular injection. The absence of a discernible extraneural hypoechoic fluid bolus on the ultrasound monitor means that either the needle tip is intravascular or the plane of imaging is inaccurate.We are also hesitant to recommend the use of ultrasound for perivascular block techniques as described by Loubert et al. 1Rather, we contend that perineural LA deposition is the safest application of ultrasound technology. There can be multiple veins traveling alongside landmark pulsatile arteries, especially in the axilla. Veins are exquisitely collapsible with even the slightest amount of pressure applied by the transducer to the skin, and can therefore vanish from sonographic view, fooling even the most experienced providers, as demonstrated by these two recent case reports.1,2We therefore use systematic scanning of the intended block site before needle insertion. Our systematic sonographic survey includes sliding the transducer distally and proximally to trace the target nerve along its expected course and examine the surrounding vasculature and tissues. Scanning is performed with varying degrees of pressure, with and without the use of color Doppler, to identify any hazards that may cross the planned trajectory of the needle. In addition, applying pulse wave Doppler over a nearby vessel during perineural injection may help to detect inadvertent intravascular injection by the characteristic high-pitch sound of turbulent flow associated with a sudden rush of fluid. Finally, however contentious,6we strongly believe that patients undergoing ultrasound-guided peripheral nerve blockade should remain awake with judicious sedation so that signs and symptoms of LA toxicity can be recognized, communicated, and treated immediately upon onset.*Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada. richard.brull@uhn.on.ca

Instructions for Obtaining Journal CME Credit

Anesthesiology’s journal-based CME program is open to all readers. Members of the American Society of Anesthesiologists participate at a preferred rate, but you need not be an ASA member or a journal subscriber to take part in this CME activity. Please complete the following steps:The American Society of Anesthesiologists is approved by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing medical education programs for physicians.The American Society of Anesthesiologists designates this educational activity for a maximum of 1 AMA PRA Category 1 Credit™ . Physicians should only claim credit commensurate with the extent of their participation in the activity.Purpose: The focus of the journal-based CME program, and the articles chosen for the program, is to educate readers on current developments in the science and clinical practice of the specialty of Anesthesiology.Target Audience: Physicians and other medical professionals whose medical specialty is the practice of anesthesia.Learning Objectives: After reading this article, participants should have a better understanding of the effectiveness of continuous preperitoneal local anesthetic infusion for postoperative pain control.Authors – Marc Beaussier, M.D., Ph.D., Hanna El’Ayoubi, M.D., Eduardo Schiffer, M.D., Maxime Rollin, M.D., Yann Parc, M.D., Ph.D., Jean-Xavier Mazoit, M.D., Ph.D., Louisa Azizi, M.D., Pascal Gervaz, M.D., Serge Rohr, M.D., Ph.D., Celine Biermann, M.D., André Lienhart, M.D., Ph.D., and Jean-Jacques Eledjam, M.D., Ph.D. Grants or research support: Supported by a grant from AstraZeneca, Rueil Malmaison, France.Consultantships or honoraria: NoneAuthors – Henrik Kehlet, M.D., and Spencer S. Liu, M.D. Grants or research support: Dr. Kehlet has received a grant from AstraZeneca, Södertälje, Sweden, to study wound infusion of local anesthetics in knee and hip replacement.Consultantships or honoraria: Dr. Liu is a consultant to Anesiva, San Francisco, California.Question Writers – Peter L. Bailey, M.D., and Leslie C. Jameson, M.D. Drs. Bailey and Jameson have no grants, research support, or consultant positions, nor do they receive any honoraria from outside sources, which may create conflicts of interest concerning this CME program.Based on the article by Beaussier et al. entitled “Continuous preperitoneal infusion of ropivacaine provides effective analgesia and accelerates recovery after colorectal http://content.wkhealth.com/linkback/openurl?issn=0003–3022&amp;volume=107&amp;issue=3&amp;spage=369&amp;part=fulltextsurgery: A randomized, double-blind, placebo-controlled study” and http://content.wkhealth.com/linkback/openurl?issn=0003–3022&amp;volume=107&amp;issue=3&amp;spage=461&amp;part=fulltextits accompanying editorial by Kehlet and Liu entitled “Continuous local anesthetic wound infusion to improve postoperative outcome: Back to the periphery?” in the September issue of Anesthesiology, choose the one correct answer for each question:1. Which of the following statements about infusion of local anesthetic at the surgical incision site for open colorectal surgery is most likely true?A. Randomized controlled trials assessing effectiveness have not been performed.B. Mental function is impaired.C. The wound infection rate is similar to rates in patients without catheters.D. Patients are resistant to using the technique.2. Which statement comparing use of a continuous preperitoneal infusion of ropivacaine in combination with patient-controlled analgesia (PCA) morphine to PCA morphine alone for pain control in patients undergoing open colorectal surgery is most likely true?A. PCA morphine alone provides better analgesia during coughing.B. The combined therapy is associated with significant reductions in morphine consumption.C. The combined therapy is associated with significantly more postoperative nausea and vomiting.D. Six weeks after surgery, combined therapy is associated with significantly more residual wound pain.3. Which of the following statements about the preperitoneal infusion of ropivacaine in patients undergoing open colorectal surgery is most likely true?A. The local anesthetic is found only in tissue in the subdermal area of the incision.B. The cost of related disposable equipment exceeds $750 (US).C. Plasma concentrations of ropivacaine are greater after 48 h than after 24 h of infusion.D. Patients do not develop symptoms of local anesthetic toxicity.4. Which statement comparing use of a continuous preperitoneal infusion of ropivacaine in combination with patient-controlled analgesia (PCA) morphine to PCA morphine alone for pain control in patients undergoing open colorectal surgery is most likely true?A. Length of hospital stay is decreasedB. Time to return of bowel function is similarC. Time to postanesthesia care unit discharge is prolonged (Aldrete score of 8)D. Quality of sleep is similar5. Which statement about the effectiveness of preperitoneal infusion of local anesthetic is most likely true?A. It effectively blocks pain receptors on the peritoneum.B. Superficial placement of the catheter provides better pain relief than preperitoneal placement after open abdominal surgery.C. The combined technical failure rate of the catheter and the pump is 10%–20%.D. It is not effective for treatment of incisional pain after a cholecystectomy.

Comparison of ropivacaine 2 mg ml−1 and prilocaine 5 mg ml−1 for i.v. regional anaesthesia in outpatient surgery

Ropivacaine 2 mg ml(-1) (0.2%) provides longer-lasting analgesia after deflation of the tourniquet cuff, with fewer side-effects, than lidocaine 5 mg ml(-1) (0.5%) after i.v. regional anaesthesia (IVRA). Whether ropivacaine 2 mg ml(-1) also exerts this advantage over prilocaine 5 mg ml(-1), the local anaesthetic of choice in IVRA in most European countries was investigated in this study. Sixty outpatients scheduled for forearm or hand surgery received IVRA with 40 ml of ropivacaine 2 mg ml(-1) (Ropi) or prilocaine 5 mg ml(-1) (Prilo) in a randomized, double-blinded fashion. The development and recovery of pin-prick analgesia and motor power of the hand, as well as ropivacaine and prilocaine plasma concentrations (n=30), were assessed during and after operation. Anaesthesia for surgery was adequate in both groups. Pin-prick analgesia was achieved at a similar rate, except in the radial nerve distribution area where at 10 min 60% of Ropi and 90% of Prilo patients had analgesia (P=0.017). At 10 min 100 and 97% had motor block of the hand in the Ropi and Prilo groups, respectively. Recovery of the sensory block in all innervation areas was already observed 2 min after the tourniquet cuff release. At 10 min after releasing the tourniquet cuff 31% of the Ropi patients and none of the Prilo patients still had analgesia in the median nerve distribution (P=0.004). At 12 min, 42% in the Ropi group and none in the Prilo group had decreased grip strength. After the release of the tourniquet, mean plasma concentrations of ropivacaine were higher than those of prilocaine. The highest individual concentration of ropivacaine was 1.65 microg ml(-1) and that of prilocaine 0.6 microg ml(-1). None of the Ropi patients experienced any symptoms of local anaesthetic toxicity. Compared with prilocaine 5 mg ml(-1), analgesia in IVRA with ropivacaine 2 mg ml(-1) developed slightly more slowly, while motor block developed at a similar rate. After the release of the tourniquet, sensation recovered quickly and at a similar rate in the two groups, except for a slightly slower recovery after ropivacaine in the innervation area of the median nerve, but no surgically useful extended analgesia after the cuff deflation was observed. Despite a 60% lower milligram-dose, ropivacaine plasma concentrations were markedly higher than those of prilocaine.

The Air Test as a Useful Indicator of Appropriate Placement of Epidural Catheter

Background: During epidural catheterization, aspiration of the content of the catheter is helpful to check for blood or CSF (cerebrospinal fluid), but the incidence of false-negative aspiration is too high to rely on this technique alone. A test dose of local anesthetics, with epinephrine, to identify intravascular or subarachnoid injection may not be as evident in the old, women in labor and patients taking -adrenergic blockers. The aim of this study was to determine the safety and efficacy of an air test to conform the appropriate placement of an epidural catheter. Methods: The authors performed a clinical trial on 160 patients, who underwent an operation under epidural anesthesia. The patients were divided into 4 groups according to the puncture site. After placement of the epidural catheter, 3 ml of air was injected through the catheter, and amounts of air aspirated via the epidural catheter were measured. Results: Eight patients were excluded due to blood or CSF was aspirates. Amoung the remaining 152 patients, 139 patients underwent successful operations under epidural anesthesia, but 13 patients needed general anesthesia. The amounts of air aspirated via the epidural catheter were about 2 ml. No patients, who had undergone the air test showed signs or symptoms of local anesthetic toxicity, PDPH (postdural puncture headache), air embolism or pneumoencephalus. Conclusions: The authors conclude that the air test is a useful alternative method for identifying the appropriate placement of epidural catheters