Cardiac arrest after interscalene brachial plexus block with ropivacaine and lidocaine

Comparing block characteristics of mixtures of short/intermediate- and long-acting local anesthetics for peripheral nerve block: a systematic review and meta-analysis

INTRODUCTION

Results from Randomized Controlled Trials (RCTs) on mixed Local Anesthetics (LA) are conflicting. We conducted a systematic review and meta-analysis on whether using mixed LA leads to faster onset of surgical block.

METHOD

We conducted systemic review and meta-analysis of RCTs. Medline and Embase without language restriction from inception to June 15, 2024, were searched. Included RCTs had to compare mixed LA to long-acting LA in adult surgical patients for onset or duration of nerve blocks. Onset time to surgical block was the primary outcome. The Cochrane Risk of Bias Tool with GRADE methodology was utilized to assess evidence quality.

RESULTS

Nineteen trials including 1060 participants met the inclusion criteria. Mixed LA modestly reduced time to surgical block (-8.4 minutes; 95% CI -12.0 to -4.8 minutes; p = 0.0001; I2 = 0.99), sensory block duration (-226.2 minutes; 95% CI -352.2 to -100.1 minutes; p = 0.002; I2 = 0.98) and motor block duration (-259.2 minutes; 95% CI -399.5 to -119.0 minutes; p = 0.003; I2 = 0.98) but not time to analgesic request duration (-130.5 minutes; 95% CI -265.9 to 4.9 minutes; p = 0.057; I2 = 0.98). GRADE scoring ranged from low to very low.

CONCLUSION

The existing evidence showed mixed LA led to a modest reduction in surgical block latency but also shortened block duration. Future studies should evaluate the role of mixed LA in lower limb blocks and optimal dosing of long-acting LA to balance onset latency and analgesic duration.

PROSPERO REGISTRATION

CRD42024552801.

PEC block versus local anesthetic infiltration in breast implant augmentation surgery: a retrospective study

INTRODUCTION

Pectoral plane (PEC) blocks are routinely used in analgesia for patients undergoing dual-plane breast augmentation with implants. Local anesthetic infiltration (LAI) is a simple alternative technique with the same aim. We evaluated both techniques.

MM

In this single-center retrospective study, patients received PEC block (ropivacaine 0.2%, 10 ml PEC I, 20 ml PEC II) or LAI. The primary outcome measure was pain, according to the visual analog scale (VAS), at 24h post-surgery. Secondary outcomes included the measure of pain at 1, 2, 6, and 12 hours post-surgery, total opioid consumption at 24h, and opioid side effects.

RESULTS

81 were finally recruited: 37 in the PEC group and 44 in the LAI group. Patient characteristics were comparable between the two groups. At 24h post-surgery, the LAI group showed a decrease in pain, with a VAS score of 0.7 vs 1.5 in the PEC group (p = 0.007). There was no difference in VAS between the two groups at 1, 2, 6, or 12 hours post-surgery. The duration of anesthesia was increased in the PEC group with 153 minutes vs 120 minutes in the LAI group (p < 0.001). There was no difference in rescue morphine consumption between the two groups.

CONCLUSIONS

We found that LAI had a superior analgesic effect at 24h after surgery for dual-plane breast implant augmentation compared with PEC block. These findings are a good indication that the LAI technique is at least as effective as PEC block while being safe, fast, and easy to use.

Analysis of bupivacaine and ropivacaine-related cardiac arrests in regional anesthesia: A systematic review of case reports

Regional anesthesia as a component of multimodal analgesia protocols has become more and more a part of modern perioperative pain management. The widespread adoption of ultrasound guidance in regional anesthesia has surely played an important role in that growth and it has significantly improved patient safety, decreased the incidence of block failure, cardiac arrest, and reduced complication rates. The objective of this systematic review is to extract, analyze, and synthesize clinical information about bupivacaine and ropivacaine related cardiac arrest that we might have a clearer picture of the clinical presentation. The literature search identified 268 potentially relevant publications and 22 relevant case reports were included in the review. Patients' demographics, types of regional anesthesia, hypotension, heart rhythm disorders, seizures, cardiac arrest, fatal outcome, recommendations and limitations on prevention and treatment of bupivacaine and ropivacaine related cardiac arrest are analyzed and discussed in the systematic review. Both bupivacaine and ropivacaine-induced local anesthetic toxicity can result in cardiac arrest. Lipid emulsion, telemetry, local anesthetic toxicity resuscitation training appears to be promising in improvement of survival but more research is needed. Improvement and encouragement of reporting the local anesthetic toxicity are warranted to improve the quality of information that can be analyzed in order to make more precise conclusion.

Local Anesthetic-Induced Central Nervous System Toxicity during Interscalene Brachial Plexus Block: A Case Series Study of Three Patients

Local anesthetics are commonly administered by nuchal infiltration to provide a temporary interscalene brachial plexus block (ISB) in a surgical setting. Although less commonly reported, local anesthetics can induce central nervous system toxicity. In this case study, we present three patients with acute central nervous system toxicity induced by local anesthetics applied during ISB with emphasis on neurological symptoms, key neuroradiological findings and functional outcome. Medical history, clinical and imaging findings, and outcome of three patients with local anesthetic-induced toxic left hemisphere syndrome during left ISB were analyzed. All patients were admitted to our neurological intensive care unit between November 2016 and September 2019. All three patients presented in poor clinical condition with impaired consciousness and left hemisphere syndrome. Electroencephalography revealed slow wave activity in the affected hemisphere of all patients. Seizure activity with progression to status epilepticus was observed in one patient. In two out of three patients, cortical FLAIR hyperintensities and restricted diffusion in the territory of the left internal carotid artery were observed in magnetic resonance imaging. Assessment of neurological severity scores revealed spontaneous partial reversibility of neurological symptoms. Local anesthetic-induced CNS toxicity during ISB can lead to severe neurological impairment and anatomically variable cerebral lesions.

Long-Term Neurological Complications Associated with Surgery and Peripheral Nerve Blockade: Outcomes after 1065 Consecutive Blocks

Peripheral nerve blockade is gaining popularity as an analgesic option for both upper or lower limb surgery. Published evidence supports the improved efficacy of regional techniques when compared to conventional opioid analgesia. The incidence of neurological deficit after surgery associated with peripheral nerve block is unclear. This paper reports on neurological outcomes occurring after 1065 consecutive peripheral nerve blocks over a one-year period from a single institution. All patients receiving peripheral nerve blocks for surgery were prospectively followed for up to 12 months to determine the incidence and probable cause of any persistent neurological deficit. Formal independent neurological review and testing was undertaken as indicated. Thirteen patients reported symptoms that warranted further investigation. A variety of probable causes were identified, with peripheral nerve block being implicated in two cases (one resolved at nine months and one remaining persistent). Overall incidence of block-related neuropathy was 0.22%.

Persistent postoperative neuropathy is a rare but serious complication of surgery associated with peripheral nerve block. Formal follow-up of all such blocks is recommended to assess causality and allow for early intervention.

Successful Resuscitation of an ASA 3 Patient following Ropivacaine-induced Cardiac Arrest

A patient with severe myocardial disease and acute-on-chronic renal failure was undergoing a brachial plexus block for formation of an arteriovenous fistula when accidental intravascular injection of ropivacaine resulted in ventricular fibrillation. Cardiopulmonary resuscitation was instituted immediately and the advanced life support algorithm was followed until the return of sinus rhythm. Although, in comparison with bupivacaine, ropivacaine appears to be a safer local anaesthetic agent in the setting of intravenous injection, the emphasis on safety should remain a priority. Awareness of the risk of central nervous system and cardiovascular toxicity and preparation for immediate commencement of resuscitation in the event of toxicity remain of paramount importance.

Beta-adrenergic activation induces cardiac collapse by aggravating cardiomyocyte contractile dysfunction in bupivacaine intoxication

In order to determine the role of the adrenergic system in bupivacaine-induced cardiotoxicity, a series of experiments were performed. In an animal experiment, male Sprague-Dawley (SD) rats under chloral hydrate anesthesia received intravenous bupivacaine, followed by an intravenous injection of adrenalin or isoprenalin, and the electrocardiogram (ECG), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), the maximum rate of rise of left ventricular pressure (+dP/dtmax) and the maximum rate of pressure decrease (-dP/dtmax) were continually monitored. In a cellular experiment, freshly isolated adult SD rat ventricular myocytes were perfused with bupivacaine at different concentrations in the presence or absence of isoprenalin, with or without esmolol. The percentage of the sarcomere shortening (bl% peak h), departure velocity (dep v) of sarcomere shortening and time to 50% of the peak speed of myocyte contraction (Tp50) was assessed by a video-based edge-detection system. In an additional experiment, Swiss mice pretreated with saline, isoprenalin, esmolol or dexmedetomidine received bupivacaine to determine the 50% lethal dose (LD50) of bupivacaine. Electron microscopy of myocardial mitochondria was performed to assess damage of these structures. To test mitochondrial reactive oxygen species (ROS) production, freshly isolated SD rat ventricular myocytes were incubated with bupivacaine in the presence of isoprenalin, with or without esmolol. First, our results showed that bupivacaine significantly reduced the LVSP and +dP/dtmax, as well as enhanced the LVEDP and -dP/dtmax (P < 0.05, vs. control, and vs. baseline). Adrenalin and isoprenalin induced a further reduction of LVSP and +dP/dtmax (P < 0.05, vs. before adrenalin or isoprenalin delivery, and vs. control). Second, bupivacaine induced a dose-dependent cardiomyocyte contractile depression. While 5.9 μmol/L or 8.9 μmol/L of bupivacaine resulted in no change, 30.0 μmol/L of bupivacaine prolonged the Tp50 and reduced the bl% peak h and dep v (P < 0.05, vs. control and vs. baseline). Isoprenalin aggravated the bupivacaine-induced cardiomyocyte contractile depression, significantly prolonging the Tp50 (P < 0.05, vs. bupivacaine alone) and reducing the dep v (P < 0.05, vs. bupivacaine alone). Third, esmolol and dexmedetomidine significantly enhanced, while isoprenalin significantly reduced, the LD50 of bupivacaine in mice. Fourth, bupivacaine led to significant mitochondrial swelling, and the extent of myocardial mitochondrial swelling in isoprenalin-pretreated mice was significantly higher than that compared with mice pretreated with saline, as reflected by the higher mitochondrial damage score (P < 0.01). Meanwhile, esmolol pretreatment significantly reduced the mitochondrial damage score (P < 0.01). Fifth, bupivacaine significantly increased the ROS in freshly isolated cardiomyocytes, and added isoprenalin induced a further enhancement of ROS production (P < 0.05, vs. bupivacaine alone). Added esmolol significantly decreased ROS production (P < 0.05, vs. bupivacaine + isoprenalin). Our results suggest that bupivacaine depressed cardiac automaticity, conductivity and contractility, but the predominant effect was contractile dysfunction which resulted from the disruption of mitochondrial energy metabolism. β-adrenergic activation aggravated the cellular metabolism disorder and therefore contractile dysfunction.

Profound Prolonged Bradycardia and Hypotension after Interscalene Brachial Plexus Block with Bupivacaine

BACKGROUND

Interscalene brachial plexus blocks have been a routinely performed method of anesthesia for shoulder surgery that decreases the need for general anesthesia, length of stay, and recovery time. We describe a case of bupivacaine toxicity after an interscalene block.

CASE REPORT

The patient was a 66-year-old man who presented to our Emergency Department by emergency medical services from an ambulatory surgery center where he had undergone rotator cuff surgery, with bradycardia and hypotension. His symptoms began upon completion of the surgery in which he received interscalene nerve block with bupivacaine and lidocaine. He was given three doses of 0.5 mg atropine and one dose of 1 mg epinephrine for a heart rate of 40 beats/min without any improvement prior to arrival. His bradycardia was refractory to atropine. He was started on a dopamine drip and transferred to the coronary care unit. The timing of his symptoms, minutes after his regional nerve block, and his complete recovery with only supportive care, make the diagnosis of bupivacaine toxicity likely. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Despite the safety profile of local anesthetics, we must be aware of their potential side affects. Whereas most adverse reactions are secondary to misdirection of anesthetic or accidental vascular puncture, local anesthetic systemic toxicity (LAST) is the major cause of significant adverse events with regional anesthesia. As regional anesthesia becomes more common, emergency physicians must be more aware of the potential complications and be able to both diagnose and treat.

Suprascapular and Interscalene Nerve Block for Shoulder Surgery

Background

Interscalene block provides optimal shoulder surgery analgesia, but concerns over its associated risks have prompted the search for alternatives. Suprascapular block was recently proposed as an interscalene block alternative, but evidence of its comparative analgesic effect is conflicting. This meta-analysis compares the analgesic effect and safety of suprascapular block versus interscalene block for shoulder surgery.

Methods

Databases were searched for randomized trials comparing interscalene block with suprascapular block for shoulder surgery. Postoperative 24-h cumulative oral morphine consumption and the difference in the area under curve for pooled rest pain scores were designated as primary outcomes. Analgesic and safety outcomes, particularly block-related and respiratory complications, were evaluated as secondary outcomes. Results were pooled using random-effects modeling.

Results

Data from 16 studies (1,152 patients) were analyzed. Interscalene block and suprascapular block were not different in 24-h morphine consumption. The difference in area under the curve of pain scores for the 24-h interval favored interscalene block by 1.1 cm/h, but this difference was not clinically important. Compared with suprascapular block, interscalene block reduced postoperative pain but not opioid consumption during recovery room stay by a weighted mean difference (95% CI) of 1.5 cm (0.6 to 2.5 cm; P &lt; 0.0001). Pain scores were not different at any other time. In contrast, suprascapular block reduced the odds of block-related and respiratory complications.

Conclusions

This review suggests that there are no clinically meaningful analgesic differences between suprascapular block and interscalene block except for interscalene block providing better pain control during recovery room stay; however, suprascapular block has fewer side effects. These findings suggest that suprascapular block may be considered an effective and safe interscalene block alternative for shoulder surgery.

Recovery From Ropivacaine-Induced or Levobupivacaine-Induced Cardiac Arrest in Rats: Comparison of Lipid Emulsion Effects

BACKGROUND

Lipid emulsion treatment appears to have application in the treatment of local anesthetic-induced cardiac arrest. To examine whether the efficacy of lipid resuscitation in the treatment of local anesthetic-induced cardiac arrest is affected by lipophilicity, the effects of lipid infusions were compared between levobupivacaine-induced (high lipophilicity) and ropivacaine-induced (lower lipophilicity) rat cardiac arrest model.

METHODS

A total of 28 female Sprague-Dawley rats were anesthetized using sevoflurane, which subsequently underwent tracheostomy, followed by femoral artery and vein cannulation. Two hours after the discontinuation of sevoflurane, either levobupivacaine 0.2% (n = 14) or ropivacaine 0.2% (n = 14) was administered at a rate of 2 mg/kg/min to the awake rats. When the pulse pressure decreased to 0, the infusion of local anesthetic was discontinued, and treatment with chest compressions and ventilation with 100% oxygen were immediately initiated. The total doses of local anesthetics needed to trigger the first seizure and pulse pressure of 0 mm Hg were calculated. The 2 groups were each subdivided into a lipid emulsion group (n = 7) and a control group (n = 7). In the lipid emulsion group, 20% lipid emulsion was administered intravenously (5 mL/kg bolus plus continuous infusion of 0.5 mL/kg/min), while in the control group, the same volume of normal saline was administered. Chest compressions were discontinued when the rate-pressure product had increased by more than 20% of baseline.

RESULTS

The cumulative doses of levobupivacaine and ropivacaine that produced seizures and 0 pulse pressure showed no significant difference. Mean arterial blood pressure (MAP) values were higher in the levobupivacaine group than in the ropivacaine group after resuscitation was initiated (P < .05). In levobupivacaine-induced cardiac arrest, heart rate and MAP values were higher in the lipid group than in the control group after starting resuscitation (P < .05); all rats in the lipid group achieved spontaneous circulation (rate-pressure product >20% baseline), while only 2 of 7 rats in the control group achieved spontaneous circulation at 10 minutes. In ropivacaine-induced cardiac arrest, there were no significant differences in heart rate and MAP between the lipid and control groups from the start of resuscitation to 10 minutes; spontaneous circulation returned in 6 of 7 lipid group rats, but in only 2 of 7 control group rats at 10 minutes.

CONCLUSIONS

Lipid emulsion treatment was more effective for levobupivacaine-induced cardiac arrest than for ropivacaine-induced cardiac arrest. Although lipid therapy is also effective for ropivacaine-induced cardiac arrest, it takes more time than in levobupivacaine-induced cardiac arrest. This suggests that the lipophilicity of local anesthetics influences the efficacy of lipid infusion when treating cardiac arrest caused by these drugs.

Localization of the brachial plexus: Sonography versus anatomic landmarks

PURPOSE

Interscalene brachial plexus blocks are performed for perioperative management of surgeries involving the shoulder. Historically, these procedures employed anatomic landmarks (AL) to determine the location of the brachial plexus as it passes between the anterior and middle scalene muscles in the neck. In this study, we compared the actual location of the brachial plexus as found with sonography (US) to the anticipated location using AL.

METHODS

The location of the brachial plexus was evaluated using US and AL in 96 subjects. The distance between the two locations was measured. A multivariate analysis of variance was used to determine the significance of the difference and a 2 × 2 analysis of variance was used to compare differences in gender, height, and body mass index.

RESULTS

The brachial plexus was located on average 1.8 cm inferior (p = 0.0001) and 0.2 cm lateral (p = 0.09) to the location determined with AL. A significant difference was also associated with gender (p = 0.03), but not with height or body mass index.

CONCLUSIONS

US is a reliable method that accurately pinpoints the roots of the brachial plexus. The brachial plexus is often located inferior to the location anticipated using AL. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:411-415, 2016.

Does Low Dose Lidocaine Cause Convulsions?

In anaesthesiology practice, lidocaine is commonly used for local and regional anaesthesia as well as to decrease haemodynamic response to intubation. Lidocain usage within the safe dose range is suggested and in case of overdose; systemic intoxication, central nervous system and cardiovascular system toxicity may occur. Convulsions, cardiac collapse and coma are reported in relation to overdoses of lidocain. In this report; the convulsion event, which occurred after injection of intravenous 1 mg kg(-1) 1% lidocaine to inhibit intubation-related hemodynamic side effects in patients scheduled for vitrectomy under general anaesthesia due to retinal detachment, is presented.

Ropivacaine versus bupivacaine for 3-in-1 block during total knee arthroplasty

PURPOSE

To compare the use of ropivacaine versus bupivacaine for 3-in-1 block during total knee arthroplasty (TKA) in terms of efficacy and safety (lack of toxicity).

METHODS

14 men and 26 women aged 58 to 77 (median, 70) years who had the American Society of Anesthesiologists (ASA) grades I to III physical status were randomised to receive ropivacaine (n=20) or bupivacaine (n=20) of a concentration of 0.5% for 3-in-1 block during TKA. The dosage was 0.5 ml/kg. In addition, a sciatic nerve block (20 ml of prilocaine 1%) was used. The onset of the block, duration of postoperative analgesia, level of motor block, and any side-effects were compared.

RESULTS

The median time to onset of block was significantly shorter in those receiving ropivacaine than bupivacaine (13 vs. 17.5 minutes, p<0.001), but the levels of motor blockade were not significantly different (p=0.355). Complete analgesia was achieved throughout the procedure. There was no significant difference between the ropivacaine and bupivacaine groups in terms of the mean duration of analgesia (398 vs. 367 minutes, p=0.62), the mean VAS scores at all time points, and the mean total morphine consumption. One patient in the ropivacaine group developed a joint haematoma and 2 patients in the bupivacaine group had excessive wound drainage. Both conditions resolved after antibiotic use.

CONCLUSION

Ropivacaine and bupivacaine showed similar anesthetic and analgesic effects, but the former had a significantly faster onset time.

Effect of interscalene brachial plexus block on heart rate variability

Background

Interscalene brachial plexus block (ISB) may be followed by cardiovascular instability. Until date, there is no clear picture available about the underlying mechanisms of ISB. In this study, we aimed to determine the changes in heart rate variability (HRV) parameters after ISB and the differences between right- and left-sided ISBs.

Methods

We prospectively studied 24 patients operated for shoulder surgery in sitting position and divided them into two respective groups: R (right-sided block = 14 pts) and L (left-sided block = 10 pts). HRV data were taken before and 30 min after the block. Ropivacaine without ephedrine was used for the ISB through an insulated block needle connected to a nerve stimulator. Statistical analysis implemented chi-square, Student's and t-paired tests. Skewed distributions were analyzed after logarithmic transformation.

Results

All the studied patients had successful blocks. Horner's syndrome signs were observed in 33.3% of the patients (R = 5/14, L = 3/10; [P = 0.769]). There were no significant differences in pre-block HRV between the groups. The application of ISB had differential effect on HRV variables: R-blocks increased QRS and QTc durations and InPNN50, while a statistical decrease was seen in InLF. L-blocks did not show any significant changes. These changes indicate a reduced sympathetic and an increased parasympathetic influence on the heart's autonomic flow after R-block.

Conclusions

Based on the obtained results we conclude that ISB, possibly through extension of block to the ipsilateral stellate ganglion, alters the autonomic outflow to the central circulatory system in a way depending on the block's side.

Epinephrine induces rapid deterioration in pulmonary oxygen exchange in intact, anesthetized rats: a flow and pulmonary capillary pressure-dependent phenomenon

BACKGROUND

Previous studies indicate epinephrine adversely affects arterial oxygenation when administered in a rat model of local anesthetic overdose. The authors tested whether epinephrine alone exerts similar effects in the intact animal.

METHODS

Anesthetized rats received a single intravenous injection of epinephrine (25, 50, or 100 mcg/kg); matched cohorts were pretreated with phentolamine (100 mcg/kg); n = 5 for each of the six treatment groups. Arterial pressure and blood gases were measured at baseline, 1 and 10 min after epinephrine administration. Pulmonary capillary pressures during epinephrine infusion with normal and increased flows were measured in an isolated lung preparation.

RESULTS

Epinephrine injection in the intact animal caused hypoxemia, hypercapnia, and acidosis at all doses. Arterial oxygen tension was reduced within 1 min of injection. Hyperlactatemia occurred by 10 min after 50 and 100 mcg/kg. Rate pressure product was decreased by 10 min after 100 mcg/kg epinephrine. Pretreatment with phentolamine attenuated these effects except at 100 mcg/kg epinephrine. In the isolated lung preparation, epinephrine in combination with increased pulmonary flow increased pulmonary capillary pressure and lung water.

CONCLUSIONS

Bolus injection of epinephrine in the intact, anesthetized rat impairs pulmonary oxygen exchange within 1 min of treatment. Effects were blunted by α-adrenergic receptor blockade. Edema occurred in the isolated lung above a threshold pulmonary capillary pressure when epinephrine treatment was coupled with an increase in pulmonary flow. These results potentially argue against using traditional doses of epinephrine for resuscitation, particularly in the anesthetized patient.

Cardiogenic shock associated with loco-regional anesthesia rescued with left ventricular assist device implantation

A healthy 53 year old man developed profound cardiogenic shock following instillation of bupivacaine-lidocaine-epinephrine solution as a locoregional anesthetic for elective outpatient shoulder surgery. Intubation, resuscitation, and transfer to the nearby hospital were done: echocardiography showed profound biventricular dysfunction; cardiac catheterization showed normal coronary arteries. Despite placement of an intra-aortic balloon pump and intravenous vasoactive drugs, the patient remained in shock. Stabilization was achieved with emergent institution of cardiopulmonary bypass and placement of a temporary left ventricular assist device (LVAD). Twenty-four hours later, cardiac function normalized and the LVAD was removed. The patient was discharged five days later and remained with normal heart function in three-year follow-up.

Clinical presentation of local anesthetic systemic toxicity: a review of published cases, 1979 to 2009

The classic description of local anesthetic systemic toxicity (LAST) generally described in textbooks includes a series of progressively worsening neurologic symptoms and signs occurring shortly after the injection of local anesthetic and paralleling progressive increases in blood local anesthetic concentration, culminating in seizures and coma. In extreme cases, signs of hemodynamic instability follow and can lead to cardiovascular collapse. To characterize the clinical spectrum of LAST and compare it to the classic picture described above, we reviewed published reports of LAST during a 30-year period from 1979 to 2009. Ninety-three cases were identified and analyzed with respect to onset of toxicity and the spectrum of signs and symptoms. Sixty percent of cases followed the classic pattern of presentation. However, in the remainder of cases, symptoms were substantially delayed after the injection of local anesthetic, or involved only signs of cardiovascular compromise, with no evidence of central nervous system toxicity. Although information gained from retrospective case review cannot establish incidence, outcomes, or comparative efficacies of treatment, it can improve awareness of the clinical spectrum of LAST and, theoretically, the diagnosis and treatment of affected patients. The analytic limitations of our method make a strong case for developing a prospective, global registry of LAST as a robust alternative for educating practitioners and optimizing management of LAST.

Potentiation of local anesthetic activity of neosaxitoxin with bupivacaine or epinephrine: development of a long-acting pain blocker

Local anesthetics effectively block and relieve pain, but with a relatively short duration of action, limiting its analgesic effectiveness. Therefore, a long-acting local anesthetic would improve the management of pain, but no such agent is yet available for clinical use. The aim of this study is to evaluate the potentiation of the anesthetic effect of neosaxitoxin, with bupivacaine or epinephrine in a randomized double-blind clinical trial. Ten healthy males were subcutaneously injected into the left and right forearms with a randomized pair of the following treatments: (i) bupivacaine (5 mg); (ii) neosaxitoxin (10 microg); (iii) neosaxitoxin (10 microg) plus bupivacaine (5 mg), and (iv) neosaxitoxin (10 microg) plus epinephrine (1:100.000), but all participant received all four formulations (in 2 ml; s.c.), with 1 month elapsing between the two round of experiments. A validated sensory and pain paradigm was used for evaluating the effect of the treatment 0-72 h after the injections, measuring sensory, pain, and mechanical touch perception threshold. The duration of the effect produced by combined treatments was longer than that by the single drugs. In conclusion, bupivacaine and epinephrine potentiate the local anesthetic effect of neosaxitoxin in humans when co-injected subcutaneously. The present results support the idea that neosaxitoxin is a new long-acting local pain blocker, with highly potential clinical use.

Upper extremity regional anesthesia: essentials of our current understanding, 2008

Brachial plexus blockade is the cornerstone of the peripheral nerve regional anesthesia practice of most anesthesiologists. As part of the American Society of Regional Anesthesia and Pain Medicine's commitment to providing intensive evidence-based education related to regional anesthesia and analgesia, this article is a complete update of our 2002 comprehensive review of upper extremity anesthesia. The text of the review focuses on (1) pertinent anatomy, (2) approaches to the brachial plexus and techniques that optimize block quality, (4) local anesthetic and adjuvant pharmacology, (5) complications, (6) perioperative issues, and (6) challenges for future research.

[Complications after regional anesthesia]

In recent years, there has been a considerable increase in the number of procedures carried out under regional anesthesia. The techniques used can be associated with a number of complications, which should be understood so that they can be recognized and managed appropriately. The overall incidence of reported complications associated with these techniques is low and therefore, with currently available data, we can only have an approximate idea of their incidence. The objective of this study is to systematically describe the complications that may arise from the use of neuraxial and peripheral regional anesthesia techniques.

[Cardiac arrest after axillary plexic anaesthesia with ropivacaine in a chronic kidney failure dialysis patient]

The local anaesthetics are responsible for an important part of morbidity and mortality during conduction anaesthesia. We describe fatal accident plexic anaesthesia with ropivacaine in spite of a classical reanimation measure in a dialysis patient.

Effects of articaine on action potential characteristics and the underlying ion currents in canine ventricular myocytes

BACKGROUND

In spite of its widespread clinical application, there is little information on the cellular cardiac effects of articaine. In the present study, the concentration-dependent effects of articaine on action potential morphology and the underlying ion currents were studied in isolated canine ventricular cardiomyocytes.

METHODS

Action potentials were recorded from the enzymatically dispersed myocytes using sharp microelectrodes (16 cells from 3 dogs). Conventional patch clamp and action potential voltage clamp arrangements were used to study the effects of articaine on transmembrane ion currents (37 cells from 14 dogs).

RESULTS

Articaine-induced concentration-dependent changes in action potential configuration including shortening of the action potentials, reduction of their amplitude and maximum velocity of depolarization (V(max)), suppression of early repolarization and depression of plateau. The EC50 value obtained for the V(max) block was 162 (sd 30) microM. Both the reduction of V(max) and action potential shortening were frequency dependent: the former was more prominent at shorter, while the latter at longer pacing cycle lengths. A rate dependent V(max) block, having rapid offset kinetics [tau = 91 (20) ms], was observed in addition to tonic block. Under voltage clamp conditions, a variety of ion currents were blocked by articaine: I(Ca) [EC50 = 471 (75) microM], I(to) [EC50 = 365 (62) microM], I(K1) [EC50 = 372 (46) microM], I(Kr) [EC50 = 278 (79) microM], and I(Ks) [EC50 = 326 (65) microM]. Hill coefficients were close to unity indicating a single binding site for articaine, except for I(K1).

CONCLUSIONS

Articaine can modify cardiac action potentials and ion currents at concentrations higher than the therapeutic range which can be achieved only by accidental venous injection. Since its suppressive effects on the inward and outward currents are relatively well balanced, the articaine-induced changes in action potential morphology may be moderate even in the case of overdose.

Ropivacaine-induced toxicity with overdose suspected after axillary brachial plexus block

Ropivacaine has a high threshold for systemic toxicity. We report and highlight a rare case in which an overdose of ropivacaine was suspected of leading to a generalized convulsion following the injection of this agent for axillary brachial plexus block (ABPB). A 25-year-old woman (height, 153 cm; weight, 48 kg; American Society of Anesthesiologists physical status I) was scheduled for finger surgery with ABPB. The perivascular sheath was identified by fascial clicks. We administered 300 mg (6.25 mg x kg(-1)) ropivacaine, while confirming that no blood flow was observed in the injection line by repeated negative aspiration tests. Ten minutes after the injection, most sensory and motor nerves were blocked effectively. Thirteen minutes after the administration, the patient lost consciousness and convulsed suddenly. No severe symptoms of cardiovascular toxicity occurred. The concentration of ropivacaine in a venous blood sample taken 28 min after the ropivacaine injection was 3.65 microg x ml(-1). She recovered with no sequelae. Limited cases have indicated high efficacy and sufficient safety for the use of 300 mg ropivacaine for ABPB. However, the toxic threshold of ropivacaine remains unclear, and the dose should be calculated in relation to the weight of the patient to prevent severe toxic complications.

Variations in corticosteroid/anesthetic injections for painful shoulder conditions: comparisons among orthopaedic surgeons, rheumatologists, and physical medicine and primary-care physicians

Background

Variations in corticosteroid/anesthetic doses for injecting shoulder conditions were examined among orthopaedic surgeons, rheumatologists, and primary-care sports medicine (PCSMs) and physical medicine and rehabilitation (PMRs) physicians to provide data needed for documenting inter-group differences for establishing uniform injection guidelines.

Methods

264 surveys, sent to these physicians in our tri-state area of the western United States, addressed corticosteroid/anesthetic doses and types used for subacromial impingement, degenerative glenohumeral and acromioclavicular arthritis, biceps tendinitis, and peri-scapular trigger points. They were asked about preferences regarding: 1) fluorinated vs. non-fluorinated corticosteroids, 2) acetate vs. phosphate types, 3) patient age, and 4) adjustments for special considerations including young athletes and diabetics.

Results

169 (64% response rate, RR) surveys were returned: 105/163 orthopaedic surgeons (64%RR), 44/77 PCSMs/PMRs (57%RR), 20/24 rheumatologists (83%RR). Although corticosteroid doses do not differ significantly between specialties (p > 0.3), anesthetic volumes show broad variations, with surgeons using larger volumes. Although 29% of PCSMs/PMRs, 44% rheumatologists, and 41% surgeons exceed "recommended" doses for the acromioclavicular joint, >98% were within recommendations for the subacromial bursa and glenohumeral joint. Depo-Medrol^® (methylprednisolone acetate) and Kenalog^® (triamcinolone acetonide) are most commonly used. More rheumatologists (80%) were aware that there are acetate and phosphate types of corticosteroids as compared to PCSMs/PMRs (76%) and orthopaedists (60%). However, relatively fewer rheumatologists (25%) than PCSMs/PMRs (32%) or orthopaedists (32%) knew that phosphate types are more soluble. Fluorinated corticosteroids, which can be deleterious to soft tissues, were used with these frequencies for the biceps sheath: 17% rheumatologists, 8% PCSMs/PMRs, 37% orthopaedists. Nearly 85% use the same non-fluorinated corticosteroid for all injections; <10% make adjustments for diabetic patients.

Conclusion

Variations between specialists in anesthetic doses suggest that surgeons (who use significantly larger volumes) emphasize determining the percentage of pain attributable to the injected region. Alternatively, this might reflect a more profound knowledge that non-surgeons specialists have of the potentially adverse cardiovascular effects of these agents. Variations between these specialists in corticosteroid/anesthetic doses and/or types, and their use in some special situations (e.g., diabetics), bespeak the need for additional investigations aimed at establishing uniform injection guidelines, and for identifying knowledge deficiencies that warrant advanced education.

Cervical epidural analgesia via a thoracic approach using nerve-stimulation guidance in adult patients undergoing total shoulder replacement surgery

BACKGROUND

Continuous cervical epidural anesthesia can provide excellent peri- and post-operative analgesia, although several factors prevent its widespread use. Advancing catheters from thoracic levels to the cervical region may circumvent these barriers, provided they are accurately positioned. We hypothesize that guiding catheters from thoracic to cervical regions using low-current epidural stimulation will have a high success rate and enable excellent analgesia in adults undergoing total shoulder arthroplasty.

METHODS

After Institutional Review Board approval, adult patients were studied consecutively. A 17-G Tuohy needle was inserted into the thoracic epidural space using a right paramedian approach with loss of resistance. A 20-G styletted epidural catheter, with an attached nerve stimulator, was primed with saline and a 1-10 mA current was applied as it advanced in a cephalad direction towards the cervical spine. Muscle twitch responses were observed and post-operative X-ray confirmed final placement. After a test dose, an infusion (2-8 ml/h) of ropivacaine 2 mg/ml and morphine 0.05 mg/ml (or equivalent) was initiated. Verbal analog pain scale scores were collected over 72 h.

RESULTS

Cervical epidural anesthesia was performed on 10 patients. Average current required to elicit a motor response was 4.8 +/- 2.0mA. Post-operative X-ray of catheter positions confirmed all catheter tips reached the desired region (C4-7). The technical success rate for catheter placement was 100% and excellent pain control was achieved. Catheters were positioned two to the left, four to the right and four to the midline.

CONCLUSION

This epidural technique provided highly effective post-operative analgesia in a patient group that traditionally experiences severe post-operative pain and can benefit from early mobilization.

Successful resuscitation of a patient with ropivacaine-induced asystole after axillary plexus block using lipid infusion*

Ropivacaine 1% 40 ml was mistakenly injected as part of an axillary plexus block in an 84-year-old woman. After 15 min the patient complained of dizziness and drowsiness and developed a generalised tonic-clonic seizure followed by an asystolic cardiac arrest. After 10 min of unsuccessful cardiopulmonary resuscitation, a bolus of 100 ml of Intralipid 20% (2 ml.kg(-1)) was administered followed by a continuous infusion of 10 ml.min(-1). After a total dose of 200 ml of Intralipid 20% had been given spontaneous electrical activity and cardiac output was restored. The patient recovered completely. We believe the cardiovascular collapse was secondary to ropivacaine absorption following the accidental overdose. This case shows that lipid infusion may have a beneficial role in cases of local anaesthetic toxicity when conventional resuscitation has been unsuccessful.

Successful defibrillation immediately after the intravascular injection of ropivacaine

PURPOSE

To report successful resuscitation of ventricular fibrillation induced by accidental intravascular injection of ropivacaine.

CLINICAL FEATURES

A 15-yr-old healthy girl weighing 59 kg was scheduled for transposition of the tibial tuberosity under combined sciatic/three-in-one block. No premedication was given. In the induction room, an iv infusion was started, along with electrocardiogram monitoring, non-invasive blood-pressure measurement and pulse-oximetry. The sciatic nerve was found with the use of a nerve stimulator at the first attempt by the classical approach of Labat. Aspiration for blood was negative and the injection of ropivacaine 0.75% without epinephrine started. Convulsions, followed within seconds by ventricular fibrillation occurred at the end of the injection of 18 mL ropivacaine 0.75%. Oxygen was administered by face mask ventilation and immediate defibrillation was successful on the second attempt (2 x 200 joules). Within two minutes convulsions stopped and normal cardiac rhythm returned. Propofol and sufentanil were injected and a laryngeal mask inserted to start general anesthesia for surgery. Postoperatively no evidence of sciatic block could be demonstrated. The patient did not remember the event and was discharged the following day with no residual effects.

CONCLUSION

This case report shows that ventricular fibrillation after unintentional intravascular injection of ropivacaine can be treated successfully when one is prepared and cardiac life support measures are taken immediately.