The effects of general anesthesia on the central nervous and cardiovascular system toxicity of local anesthetics

The pharmacokinetics of levobupivacaine 0.5% after infraorbital or inferior alveolar block in anesthetized dogs

Introduction

Data are lacking on the pharmacokinetic profile and safety of levobupivacaine (LB) used for regional anesthesia of the maxilla and mandibles in dogs.

Methods

Infraorbital block (n = 10), inferior alveolar block (n = 10) or both infraorbital and inferior alveolar blocks (n = 10) were administered to dogs undergoing dental surgery under isoflurane anesthesia. The dose of LB was calculated as 0.11 ml/kg^2/3 for the infraorbital block and 0.18 ml/kg^2/3 for the inferior alveolar block. Blood samples were collected before and immediately after administration of the oral blocks, and 3, 4, 7, 12, 17, 32, 47, 62, 92, and 122 min thereafter. Quantification of LB in plasma was performed by LC-MS/MS.

Results and discussion

The results are presented as median and interquartile range. In dogs in which all four quadrants of the oral cavity were desensitized with LB, the C _max was 1,335 (1,030-1,929) ng/ml, the T _max was 7 (4-9.5) min, and the AUC_{(0 → 120)} was 57,976 (44,954-96,224) ng min/ml. Plasma concentrations of LB were several times lower than the reported toxic concentrations, and no signs of cardiovascular depression or neurotoxicity were observed in any of the dogs, suggesting that the occurrence of severe adverse effects after administration of LB at the doses used in this study is unlikely.

Alleviation of prilocaine-induced epileptiform activity and cardiotoxicity by thymoquinone

PURPOSE

This study investigated whether thymoquinone (TQ) could alleviate central nervous system (CNS) and cardiovascular toxicity of prilocaine, a commonly used local anesthetic.

METHODS

Rats were randomized to the following groups: control, prilocaine treated, TQ treated and prilocaine + TQ treated. Electroencephalography and electrocardiography electrodes were placed and trachea was intubated. Mechanical ventilation was initiated, right femoral artery was cannulated for continuous blood pressure measurements and blood-gas sampling while the left femoral vein was cannulated for prilocaine infusion. Markers of myocardial injury, reactive oxygen/nitrogen species (ROS/RNS) generation and total antioxidant capacity (TAC) were assayed by standard kits. Aquaporin-4 (AQP4), nuclear factor(NF)κB-p65 and -p50 subunit in brain tissue were evaluated by histological scoring.

RESULTS

Blood pH and partial oxygen pressure, was significantly decreased after prilocaine infusion. The decrease in blood pH was alleviated in the prilocaine + TQ treated group. Prilocaine produced seizure activity, cardiac arrhythmia and asystole at significantly lower doses compared to prilocaine + TQ treated rats. Thymoquinone administration attenuated levels of myocardial injury induced by prilocaine. Prilocaine treatment caused increased ROS/RNS formation and decreased TAC in heart and brain tissue. Thymoquinone increased heart and brain TAC and decreased ROS/RNS formation in prilocaine treated rats. AQP4, NFκB-p65 and NFκB-p50 expressions were increased in cerebellum, cerebral cortex, choroid plexus and thalamic nucleus in prilocaine treated rats. Thymoquinone, decreased the expression of AQP4, NFκB-p65 and NFκB-p50 in brain tissue in prilocaine + TQ treated rats.

CONCLUSION

Results indicate that TQ could ameliorate prilocaine-induced CNS and cardiovascular toxicity.

Pharmacokinetics of intraperitoneal and subcutaneous levobupivacaine in anesthetized rats

BACKGROUND

We compared the pharmacokinetics of levobupivacaine when administered intraperitoneally, subcutaneously, and intravenously in an anesthetized rat model, to estimate the toxicity risk of a local anesthetic when absorbed from the peritoneum.

METHODS

Thirty-two rats were anesthetized with sevoflurane. In Experiment 1, we administered 5.0 mg/kg of levobupivacaine intraperitoneally (IP) (n = 7), subcutaneously (SC) (n = 6), or intravenously (IV) (n = 6). In Experiment 2, we administered 2.5 mg/kg of levobupivacaine IP (n = 7) or SC (n = 6). Data are shown as median [range] of Experiment 1.

RESULTS

In either of experiments, the time to reach maximum plasma concentration of levobupivacaine was shorter in the IP group than in the SC group (IP: 2 [2-5] min; SC: 5 [2-10] min; P = 0.04), and the maximum concentration of levobupivacaine did not differ between the IP and SC groups (IP: 0.45 [0.05-0.67] µg/mL; SC: 0.47 [0.21-0.62] µg/mL; P = 0.90). The area under the curve from time 0 to 120 min after levobupivacaine administration was significantly higher in the SC group than in the IP group in both experiments (IP: 0.29 [0.10-0.54] mg h/L; SC: 0.78 [0.39-0.98] mg h/L; P = 0.04).

CONCLUSION

Levobupivacaine is rapidly absorbed following IP administration, but its maximum plasma concentration within 2 h following IP administration is no statistical difference as that following SC administration. On the other hand, when levobupivacaine is given subcutaneously, T_max can exceed 1 h, so we need to be aware of local anesthetic toxicity during this period.

Radio-induced cardiotoxicity: From physiopathology and risk factors to adaptation of radiotherapy treatment planning and recommended cardiac follow-up

Cancer and cardiovascular disease (CVD) are the leading cause of mortality worldwide, and breast cancer (BC) the most common malignancy affecting women worldwide. Radiotherapy is an important component of BC treatment and participates in CVD occurrence. It seems, therefore, crucial to gather both radiation oncology and cardiology medical fields to improve the follow-up quality of our BC patients. This review aims at updating our knowledge regarding cardiotoxicities risk factors, and consequently, doses constraints in case of 3D-conformal and IMRT treatment planning. Then we will develop how to reduce cardiac exposure and what kind of cardiac follow-up we could recommend to our breast cancer patients.

-Effects of Local Anesthetics on Smooth Muscle Tissue in Rat Trachea: An In Vitro Study

OBJECTIVES

We evaluated the muscle responses of rat trachea to LA drugs, such as lidocaine and prilocaine, in terms of airway spasms.

MATERIALS AND METHODS

A total of 16 male rats were used. After ketamine anesthesia, the tracheal ring of each rat was removed and placed in the organ bath in the Krebs solution. The rat tracheal veins were randomly divided into two groups based on the LA applied at the basal tonus level: group 1 (n=8), lidocaine; group 2 (n=8), prilocaine. Second, the baths were washed. Supramaximal contraction was obtained by applying acetylcholine to the tracheal rings (n=16) at a basal tonus level. The rat tracheas with supramaximal contraction were randomly divided into two groups: group 3 (n=8), lidocaine; group 4 (n=8), prilocaine. The contraction responses of each group were recorded and statistically compared.

RESULTS

Lidocaine constituted a significant relaxation response in the tracheal tissue in both basal tonus and supramaximal tonus levels. Moreover, it was observed that the relaxation of lidocaine was higher in the supramaximal contraction than in the basal tonus tension level. However, for prilocaine, no significant change was observed in both tonus levels.

CONCLUSION

This study suggests that lidocaine as a LA drug should be preferred as the first choice in patients with respiratory risk, and that its use over prilocaine should be preferred, if supported by advanced clinical studies.

Propofol protects human cardiac cells against chemical hypoxiainduced injury by regulating the JNK signaling pathways

Propofol is a widely used intravenous anesthetic shown to exert a cardioprotective role against oxidative stress and ischemia/reperfusion injury in rat cardiac H9c2 cells. However, the regulatory mechanisms and functions of propofol in human cardiomyocytes remain unknown. The present study chemically induced hypoxia with cobalt chloride (CoCl₂) to mimic cardiomyocyte ischemic injury in human cardiac AC16 and HCM cells. To investigate its underlying mechanisms, propofol was added to the cells before the chemical hypoxia phase. The present results suggested that, in response to hypoxia, mitochondrial membrane potential was lost, and cardiomyocyte viability and superoxide dismutase levels decreased. However, the present results showed that reactive oxygen species and malondialdehyde levels increased. The present results suggested that these effects were significantly reversed following propofol treatment. Additionally, the present results suggested that the protective effect of propofol against CoCl₂-induced injury may be inhibited by the activation of the JNK signaling pathways. The present results indicated that propofol pre-treatment inhibited CoCl₂-induced myocardial injury by preventing mitochondrial dysfunction, which may be partially due to the activation of the JNK signaling pathways. Therefore, propofol may exert anti-oxidative effects in human cardiac cells. The present results suggested that propofol may be used as a treatment for oxidative stress-related cardiac disorders.

A review of factors affecting analgesic selection in large animals undergoing translational research

The widespread physiological effects of pain in experimental animals are likely to reduce the validity of data except when pain itself is studied. Appropriately prescribed analgesics will limit pain and improve the welfare of animals undergoing noxious experimental procedures. However, their injudicious use may also introduce variability in data and limit study reproducibility. Optimizing both animal welfare and the value of scientific data from experimental studies requires the ability to identify, quantify and treat animal pain by applying a knowledge of analgesic pharmacology that is sympathetic to study objectives. This review first examines the reasons for promoting analgesic use in translational animal research and, in focussing on pigs and small ruminants, then identifies factors that should be considered when devising analgesic plans.

In vitro study of a glucose attached poly(aryl ether) dendron based gel as a drug carrier for a local anaesthetic

A poly(aryl ether) dendron based gelator as an efficient transdermal drug carrier for the controlled release of prilocaine hydrochloride.

Plasma bupivacaine concentrations following orbital injections in cats

OBJECTIVE

To determine plasma bupivacaine concentrations after retrobulbar or peribulbar injection of bupivacaine in cats.

STUDY DESIGN

Randomized, crossover, experimental trial with a 2 week washout period.

ANIMALS

Six adult healthy cats, aged 1-2 years, weighing 4.6 ± 0.7 kg.

METHODS

Cats were sedated by intramuscular injection of dexmedetomidine (36-56 μg kg^-1) and were administered a retrobulbar injection of bupivacaine (0.75 mL, 0.5%; 3.75 mg) and iopamidol (0.25 mL), or a peribulbar injection of bupivacaine (1.5 mL, 0.5%; 7.5 mg), iopamidol (0.5 mL) and 0.9% saline (1 mL) via a dorsomedial approach. Blood (2 mL) was collected before and at 5, 10, 15, 22, 30, 45, 60, 120, 240 and 480 minutes after bupivacaine injection. Atipamezole was administered approximately 30 minutes after bupivacaine injection. Plasma bupivacaine and 3-hydroxybupivacaine concentrations were determined using liquid chromatography-mass spectrometry. Bupivacaine maximum plasma concentration (C_max) and time to C_max (T_max) were determined from the data.

RESULTS

The bupivacaine median (range) C_max and T_max were 1.4 (0.9-2.5) μg mL^-1 and 17 (4-60) minutes, and 1.7 (1.0-2.4) μg mL^-1, and 28 (8-49) minutes, for retrobulbar and peribulbar injections, respectively. In both treatments the 3-hydroxybupivacaine peak concentration was 0.05-0.21 μg mL^-1.

CONCLUSIONS AND CLINICAL RELEVANCE

In healthy cats, at doses up to 2 mg kg^-1, bupivacaine peak plasma concentrations were approximately half that reported to cause arrhythmias or convulsive electroencephalogram (EEG) activity in cats, and about one-sixth of that required to produce hypotension.

Intravenous Lipid Emulsion for Levobupivacaine Intoxication in Acidotic and Hypoxaemic Pigs

Intravenous lipid emulsion is, in some countries, the recommended treatment for local anaesthetic toxicity. Systemic local anaesthetic toxicity results in hypoxaemia and acidosis, and whether this influences the effects of lipid therapy on drug concentrations and cardiovascular recovery is currently unknown. Twenty anaesthetised pigs were given a 3 mg/kg bolus of levobupivacaine followed by a five-minute phase of hypoventilation and 1 mmol/kg of lactic acid over one minute. After lactic acid infusion, pigs were treated, in randomised order, with either 20% lipid emulsion or Ringer's acetate for 30 minutes: a 1.5 ml/kg bolus followed by a 0.25 ml/kg/minute infusion. Haemodynamic parameters were recorded and blood samples were collected for pharmacokinetic analysis. There was no difference between the groups in the area under the plasma levobupivacaine concentration–time curve (AUC) or between that and AUC of unentrapped levobupivacaine in the Lipid group, or in the plasma half-lives. The cardiovascular outcome and normalisation of the electrocardiogram were similar in both groups. Five pigs developed marked hypotension: one in both groups died, while two in the Lipid group and one in the Ringer group needed adrenaline. Administration of lipid emulsion did not improve cardiovascular recovery from levobupivacaine toxicity exacerbated by acidosis and hypoxaemia. Lipid emulsion did not entrap levobupivacaine or affect levobupivacaine pharmacokinetics.

Intravenous lidocaine increases the depth of anaesthesia of propofol for skin incision--a randomised controlled trial

BACKGROUND

The anaesthetic potency of intravenous propofol is quantified by its Cp50 value, which is defined as the plasma concentration required to prevent movement response in 50% of patients to surgical stimuli. We hypothesised that, in addition to propofol anaesthesia, an intravenous bolus of lidocaine 1.5 mg/kg will decrease the Cp50 value of propofol during anaesthesia.

METHODS

We enrolled 54 elective surgical patients undergoing propofol-based anaesthesia, and randomised them to either lidocaine 1.5 mg/kg, lidocaine 0.5 mg/kg or placebo (NaCl 0.9%) 3 min before skin incision. The propofol Cp50 value was then calculated using the 'up-and-down' method of Dixon and Massey.

RESULTS

There was no significant reduction in propofol requirements after the administration of 0.5 mg/kg lidocaine from 8.5 μg/ml [confidence interval (CI) 6.0-11.625] to 8.25 μg/ml (CI 6.75-9.76); however, a bolus of 1.5 mg/kg lidocaine decreased the Cp50 value of propofol by 42% from 8.5 μg/ml (CI 6.0-11.625) to 4.92 μg/ml (CI 4.5-5.78) (P < 0.05).

CONCLUSION

An intravenous bolus injection of 1.5 mg/kg lidocaine 2% caused a significant reduction of the propofol Cp50 value.

Local Anaesthetic Systemic Toxicity in a Patient under General Anaesthesia (GA): A Diagnostic Challenge

Local anaesthetic systemic toxicity (LAST) is one of the most dreadful complications after local anaesthetic (LA) use and it is very difficult to manage. The diagnosis of LAST is purely clinical and its presentation is usually obscured in a sedated or anaesthetized patient. A 25-year-old male patient undergoing laparotomy for acute duodenal perforation under general anaesthesia developed seizures after epidural administration of 0.5% bupivacaine. All other possible causes of seizures were ruled out. Seizures were controlled with antiepileptic drugs and patient recovered fully after withholding LA administration. Although, lipid rescue is recommended for LAST, our patient was managed without its use. We, therefore, recommend that utmost care and vigilance should be exercised while using local anesthetics as there is no perfectly accurate method to rule out intravascular administration of LA. Even, if LA is correctly used, LA is detected in plasma due to its systemic absorption from injection site.

A critical review of anaesthetised animal models and alternatives for military research, testing and training, with a focus on blast damage, haemorrhage and resuscitation

Military research, testing, and surgical and resuscitation training, are aimed at mitigating the consequences of warfare and terrorism to armed forces and civilians. Traumatisation and tissue damage due to explosions, and acute loss of blood due to haemorrhage, remain crucial, potentially preventable, causes of battlefield casualties and mortalities. There is also the additional threat from inhalation of chemical and aerosolised biological weapons. The use of anaesthetised animal models, and their respective replacement alternatives, for military purposes -- particularly for blast injury, haemorrhaging and resuscitation training -- is critically reviewed. Scientific problems with the animal models include the use of crude, uncontrolled and non-standardised methods for traumatisation, an inability to model all key trauma mechanisms, and complex modulating effects of general anaesthesia on target organ physiology. Such effects depend on the anaesthetic and influence the cardiovascular system, respiration, breathing, cerebral haemodynamics, neuroprotection, and the integrity of the blood-brain barrier. Some anaesthetics also bind to the NMDA brain receptor with possible differential consequences in control and anaesthetised animals. There is also some evidence for gender-specific effects. Despite the fact that these issues are widely known, there is little published information on their potential, at best, to complicate data interpretation and, at worst, to invalidate animal models. There is also a paucity of detail on the anaesthesiology used in studies, and this can hinder correct data evaluation. Welfare issues relate mainly to the possibility of acute pain as a side-effect of traumatisation in recovered animals. Moreover, there is the increased potential for animals to suffer when anaesthesia is temporary, and the procedures invasive. These dilemmas can be addressed, however, as a diverse range of replacement approaches exist, including computer and mathematical dynamic modelling of the human body, cadavers, interactive human patient simulators for training, in vitro techniques involving organotypic cultures of target organs, and epidemiological and clinical studies. While the first four of these have long proven useful for developing protective measures and predicting the consequences of trauma, and although many phenomena and their sequelae arising from different forms of trauma in vivo can be induced and reproduced in vitro, non-animal approaches require further development, and their validation and use need to be coordinated and harmonised. Recommendations to these ends are proposed, and the scientific and welfare problems associated with animal models are addressed, with the future focus being on the use of batteries of complementary replacement methods deployed in integrated strategies, and on greater transparency and scientific cooperation.

Optimal management of the critically ill: anaesthesia, monitoring, data capture, and point-of-care technological practices in ovine models of critical care

Animal models of critical illness are vital in biomedical research. They provide possibilities for the investigation of pathophysiological processes that may not otherwise be possible in humans. In order to be clinically applicable, the model should simulate the critical care situation realistically, including anaesthesia, monitoring, sampling, utilising appropriate personnel skill mix, and therapeutic interventions. There are limited data documenting the constitution of ideal technologically advanced large animal critical care practices and all the processes of the animal model. In this paper, we describe the procedure of animal preparation, anaesthesia induction and maintenance, physiologic monitoring, data capture, point-of-care technology, and animal aftercare that has been successfully used to study several novel ovine models of critical illness. The relevant investigations are on respiratory failure due to smoke inhalation, transfusion related acute lung injury, endotoxin-induced proteogenomic alterations, haemorrhagic shock, septic shock, brain death, cerebral microcirculation, and artificial heart studies. We have demonstrated the functionality of monitoring practices during anaesthesia required to provide a platform for undertaking systematic investigations in complex ovine models of critical illness.

Procaine, a state-dependent blocker, inhibits HERG channels by helix residue Y652 and F656 in the S6 transmembrane domain

The article evaluated the inhibitory action of procaine on wild-type and mutated HERG potassium channel current (I(HERG)) to determine whether mutations in the S6 region are important for the inhibition of I(HERG) by procaine. HERG channels (WT, Y652A, and F656A) were expressed in Xenopus laevis oocytes and studied using the standard two-microelectrode voltage-clamp technique. The results revealed that WT HERG is blocked in a concentration-, voltage-, and state-dependent manner by procaine ([IC₅₀] = 34.79 μM). The steady state activation curves slightly move to the negative, while inactivation parameters move to the positive in the presence of procaine. Time-dependent test reveals that voltage-dependent I(HERG) blockade occurs extremely rapidly. Furthermore, the mutation to Ala of Y652 and F656 produce about 11-fold and 18-fold increases in IC₅₀ for I(HERG) blockade, respectively. Simultaneously, for Y652A, the steady state activation and inactivation parameters are shifted to more positive values after perfusion of procaine. Conclusively, procaine state-dependently inhibits HERG channels (WT, Y652A, and F656A). The helix residues Y652 and F656 in the S6 transmembrane domain might play a role in interaction of the drug with the channel.

Lipid emulsion for local anesthetic systemic toxicity

The accidental overdose of local anesthetics may prove fatal. The commonly used amide local anesthetics have varying adverse effects on the myocardium, and beyond a certain dose all are capable of causing death. Local anesthetics are the most frequently used drugs amongst anesthetists and although uncommon, local anaesthetic systemic toxicity accounts for a high proportion of mortality, with local anaesthetic-induced cardiac arrest particularly resistant to standard resuscitation methods. Over the last decade, there has been convincing evidence of intravenous lipid emulsions as a rescue in local anesthetic-cardiotoxicity, and anesthetic organisations, over the globe have developed guidelines on the use of this drug. Despite this, awareness amongst practitioners appears to be lacking. All who use local anesthetics in their practice should have an appreciation of patients at high risk of toxicity, early symptoms and signs of toxicity, preventative measures when using local anesthetics, and the initial management of systemic toxicity with intravenous lipid emulsion. In this paper we intend to discuss the pharmacology and pathophysiology of local anesthetics and toxicity, and the rationale for lipid emulsion therapy.

Midazolam in rabbits terminates dysrhythmias caused by intracerebroventricular ropivacaine

The current study was designed to investigate the mechanisms by which ropivacaine may act within the central nervous system (CNS) to produce cardiotoxicity. Eighty New Zealand rabbits were divided into four groups randomly. In Group 1, 20 rabbits received intracerebroventricular (icv) saline, and then received icv ropivacaine 30 min later. In Group 2, 20 rabbits received icv ropivacaine. Whenever dysrhythmias continued for more than 5 min, 0.1 ml saline was administered into the left cerebral ventricle. Ten minutes later, 0.1 ml midazolam was given into the left lateral ventricle. In Group 3, 20 rabbits received icv ropivacaine, and once the dysrhythmias developed, the inspired isoflurane concentration was increased from 0.75% to 1.50%. In Group 4, 20 animals received an intravenous (iv) phenylephrine infusion until dysrhythmias occurred. In Group 1, the rabbits did not develop dysrhythmias in response to icv saline, whereas dysrhythmias did develop in these animals after icv ropivacaine. In Group 2, icv saline had no effect on the dysrhythmias; however, icv midazolam terminated cardiac dysrhythmias. In Group 3, an increase in the concentration of the inspired isoflurane had no effect on dysrhythmias. In Group 4, icv midazolam had no effect on dysrhythmias in response to iv phenylephrine. Ropivacaine administered directly into the CNS is capable of producing cardiac dysrhythmias; midazolam terminated dysrhythmias presumably by potentiation of γ-aminobutyric acid (GABA) receptor activity. Our results suggest that ropivacaine produces some of its cardiotoxicity not only by the direct cardiotoxicity of the drug, but also by the CNS effects of ropivacaine.

Cardiac toxicity in breast cancer patients: from a fractional point of view to a global assessment

When focusing on heart disease, most available studies split the two different parts of the adjuvant treatment, i.e., systemic therapies and radiation therapy, making it difficult to implement efficient strategies for preventing treatment-induced cardiac toxicity. This paper reviews the current understanding of treatments-induced cardiac toxicity in a global approach. Many factors should be considered when assessing the cardiac hazard. Treatment-related risk factors include heart dose exposure, chemotherapy, targeted agents such as HER2 inhibitors, but also endocrine agents, or anesthetic procedure. Patients' characteristics should also be taken into account. Age, menopausal status, stress, previous history of cardiac disease, genetic profile, and body mass index could all impact on cardiac function after adjuvant therapies. Cardiac toxicity should not be analyzed as the consequence of a specific therapy, but should be considered as the result of additive or supra-additive toxicities. By this way, it will be possible to implement new strategies for preventing treatment-induced cardiac toxicity.

The acute toxicity of local anesthetics

IMPORTANCE OF THE FIELD

Systemic toxicity, usually from overdose or intravascular dose, is feared because it mainly affects the heart and brain, and may be acutely life-threatening.

AREAS COVERED IN THIS REVIEW

Pharmacological studies of local anesthetic toxicity have largely been reviewed primarily relating to the evaluation of ropivacaine and levobupivacaine during the past decade. This review/opinion focuses more on the principles and concepts underlying the main models used, from chemical pharmacological and pharmacokinetic perspectives.

WHAT THE READER WILL GAIN

Research models required to produce pivotal toxicity data are discussed. The potencies for neural blockade and systemic toxicity are associated across virtually all models, with some deviations through molecular stereochemistry. These models show that all local anesthetics can produce direct cardiovascular system toxicity and CNS excitotoxicity that may further affect the cardiovascular system response. Whereas the longer-acting local anesthetics are more likely to cause cardiac death by malignant arrhythmias, the shorter-acting agents are more likely to cause cardiac contraction failure. In most models, equi-anesthetic doses of ropivacaine and levobupivacaine are less likely to produce serious toxicity than bupivacaine.

TAKE HOME MESSAGE

Of the various models, this reviewer favors a whole-body large animal preparation because of the comprehensive data collection possible. The conscious sheep preparation has contributed more than any other, and may be regarded as the de facto 'standard' experimental model for concurrent study of local anesthetic toxicity ± pharmacokinetics, using experimental designs that can reproduce the toxicity seen in clinical accidents.

Regional Anaesthesia for Bilateral Upper Limb Surgery: A Review of Challenges and Solutions

Regional anaesthesia for bilateral upper limb surgery can be challenging, yet surgeons are becoming increasingly interested in performing bilateral procedures at the same operation. Anaesthetists have traditionally avoided bilateral brachial plexus block due to concerns about local anaesthetic toxicity, phrenic nerve block and pneumothorax. We discuss these three concerns and review whether advances in ultrasound guidance and nerve catheter techniques should make us reconsider our options. A search of Medline and EMBASE from 1966 to January 2009 was conducted using multiple search terms to identify techniques of providing anaesthesia or analgesia for bilateral upper limb surgery and potential side-effects. Ultrasound imaging and nerve catheter techniques have led to a reduction in dose requirements for effective blocks without side-effects. Effective regional anaesthesia can be performed for bilateral surgery while remaining within recommended safe dose limits. Spacing blocks apart in time can further reduce potential toxicity issues, such that peak absorption rates for each block do not coincide. Since phrenic nerve block remains an issue even with low doses of local anaesthesia, bilateral interscalene blocks are still not recommended. Peripheral nerve blocks have excellent safety profiles and are ideal for ultrasound guidance. Regional anaesthesia can be a suitable option for bilateral upper limb surgery.

A review of local anesthetic cardiotoxicity and treatment with lipid emulsion

Cardiovascular collapse from accidental local anesthetic toxicity is a rare but catastrophic complication of regional anesthesia. The long-acting amide local anesthetics bupivacaine, levobupivacaine and ropivacaine have differential cardiac toxicity, but all are capable of causing death with accidental overdose. In recent times, the chance discovery that lipid emulsion may improve the chance of successful resuscitation has lead to recommendations that it should be available in every location where regional anesthesia is performed. This review will outline the mechanisms of local anesthetic toxicity and the rationale for lipid emulsion therapy.

Pharmacologic management of acute pediatric pain

The accurate assessment and effective treatment of acute pain in children in the hospital setting is a high priority. During the past 2 to 3 decades, pediatric pain management has gained tremendous knowledge with respect to the understanding of developmental neurobiology, developmental pharmacology the use of analgesics in children, the use of regional techniques in children, and of the psychological needs of children in pain. A wide range of medications is available to treat a variety of pain types. This article provides an overview of the most common analgesic medications and techniques used to treat acute pain in children.