Nanotherapeutics for Alleviating Anesthesia-Associated Complications

Current management of anesthesia-associated complications falls short in terms of both efficacy and safety. Nanomaterials with versatile properties and unique nano-bio interactions hold substantial promise as therapeutics for addressing these complications. This review conducts a thorough examination of the existing nanotherapeutics and highlights the strategies for developing prospective nanomedicines to mitigate anesthetics-related toxicity. Initially, general, regional, and local anesthesia along with the commonly used anesthetics and related prevalent side effects are introduced. Furthermore, employing nanotechnology to prevent and alleviate the complications of anesthetics is systematically demonstrated from three aspects, that is, developing 1) safe nano-formulization for anesthetics; 2) nano-antidotes to sequester overdosed anesthetics and alter their pharmacokinetics; 3) nanomedicines with pharmacodynamic activities to treat anesthetics toxicity. Finally, the prospects and challenges facing the clinical translation of nanotherapeutics for anesthesia-related complications are discussed. This work provides a comprehensive roadmap for developing effective nanotherapeutics to prevent and mitigate anesthesia-associated toxicity, which can potentially revolutionize the management of anesthesia complications.

Management of acute carbamazepine poisoning: A narrative review

Standard management protocols are lacking and specific antidotes are unavailable for acute carbamazepine (CBZ) poisoning. The objective of this review is to provide currently available information on acute CBZ poisoning, including its management, by describing and summarizing various therapeutic methods for its treatment according to previously published studies. Several treatment methods for CBZ poisoning will be briefly introduced, their advantages and disadvantages will be analyzed and compared, and suggestions for the clinical treatment of CBZ poisoning will be provided. A literature search was performed in various English and Chinese databases. In addition, the reference lists of identified articles were screened for additional relevant studies, including non-indexed reports. Non-peer-reviewed sources were also included. In the present review, 154 articles met the inclusion criteria including case reports, case series, descriptive cohorts, pharmacokinetic studies, and in vitro studies. Data on 67 patients, including 4 fatalities, were reviewed. Based on the summary of cases reported in the included articles, the cure rate of CBZ poisoning after symptomatic treatment was 82% and the efficiency of hemoperfusion was 58.2%. Based on the literature review, CBZ is moderately dialyzable and the recommendation for CBZ poisoning is supportive management and gastric lavage. In severe cases, extracorporeal treatment is recommended, with hemodialysis as the first choice.

Intravenous lipid emulsion for the treatment of poisonings in 313 dogs and 100 cats (2016-2020)

Introduction

The aim of this retrospective study was to analyze the effect and potential adverse effects of intravenous lipid emulsion (ILE) in poisoned dogs and cats over a 5 years period.

Methods

Medical records of 313 dogs and 100 cats receiving ILE between 2016-2020 were analyzed for suspected toxicant, clinical signs, ILE dosages and frequency, the effect and adverse effects of ILE, and patient outcome.

Results

Dogs and cats were poisoned with mostly unidentified toxicants (48%), rodenticides (8%), recreational drugs and nuts (7% each) and other toxicants. Clinical signs included neurologic deficits (63%), cardiovascular signs (29%), thermoregulation (21%) or gastrointestinal abnormalities (17%). Treatment with ILE was initiated within a median of 6.0 h (1.0-91.0 h) after poisoning. Dogs and cats received a total amount of median 8.0 mL/kg (1.5-66.6 mL/kg) and 15.8 mL/kg (1.8-69.4 mL/kg) ILE, respectively. A positive effect was observed in 74% of the patients, whereas clinical signs worsened in 4% of the patients after ILE administration. No subjective effect was detected in 22% of the patients. Suspected or possible adverse effects of ILE occurred in 6% of the patients, including neurological signs (temporarily reduced consciousness and ataxia), bradycardia, hyperthermia, vomiting, diarrhea, respiratory distress, worsening of the general behavior, facial swelling, and thrombophlebitis. The overall survival rate was 96%. One dog who potentially experienced adverse events was euthanized.

Conclusion

ILE treatment was successful in most patients but can be associated with adverse effects. Administration of ILE should be carefully selected on an individual basis after weighing the possible benefits against potential adverse effects.

Lipid Emulsion to Treat Acute Poisonings: Mechanisms of Action, Indications, and Controversies

Biodetoxification using intravenous lipid emulsion (ILE) in acute poisoning is of growing interest. As well as for local anesthetics, ILE is currently used to reverse toxicity caused by a broad-spectrum of lipophilic drugs. Both pharmacokinetic and pharmacodynamic mechanisms have been postulated to explain its possible benefits, mainly combining a scavenging effect called "lipid sink" and cardiotonic activity. Additional mechanisms based on ILE-attributed vasoactive and cytoprotective properties are still under investigation. Here, we present a narrative review on lipid resuscitation, focusing on the recent literature with advances in understanding ILE-attributed mechanisms of action and evaluating the evidence supporting ILE administration that enabled the international recommendations. Many practical aspects are still controversial, including the optimal dose, the optimal administration timing, and the optimal duration of infusion for clinical efficacy, as well as the threshold dose for adverse effects. Present evidence supports the use of ILE as first-line therapy to reverse local anesthetic-related systemic toxicity and as adjunct therapy in lipophilic non-local anesthetic drug overdoses refractory to well-established antidotes and supportive care. However, the level of evidence is low to very low, as for most other commonly used antidotes. Our review presents the internationally accepted recommendations according to the clinical poisoning scenario and provides the precautions of use to optimize the expected efficacy of ILE and limit the inconveniences of its futile administration. Based on their absorptive properties, the next generation of scavenging agents is additionally presented. Although emerging research shows great potential, several challenges need to be overcome before parenteral detoxifying agents could be considered as an established treatment for severe poisonings.

A case of refractory ventricular fibrillation after caffeine poisoning successfully treated by supportive care

Caffeine (1,3,7-trimethylxantine), a structural analog of adenosine, is widely used as a central nervous system stimulant in beverages and drugs. Caffeine overdose induces hypokalemia, fatal ventricular fibrillation, and cardiac arrest, resulting in death. We describe a case of caffeine overdose that presented with refractory ventricular fibrillation that was treated with supportive care because invasive care for severely ill patients was limited due to the COVID-19 pandemic. A 20-year-old woman with no underlying medical history ingested 90,200-mg caffeine tablets (total dose 18 g) in a suicide attempt. She was transported to the emergency department 45 min after ingestion with dizziness, palpitations, nausea, and vomiting. She developed cardiac arrest 80 min after ingesting the caffeine, with refractory ventricular tachycardia that recurred for about 2.5 h. Advanced life support including defibrillation was started immediately and we gave intravenous Intralipid emulsion, potassium chloride, amiodarone, and esmolol, without hemodialysis or extracorporeal membrane oxygenation (ECMO). The ventricular fibrillation was stopped 4 h after ingestion. As supportive care, mechanical ventilation, sedatives, and neuromuscular blockade were continued until 12 h after ingestion. Although she suffered from prolonged, refractory ventricular tachycardia, she recovered without complications. This case report describes the clinical course of severe caffeine intoxication without an active elimination method, such as hemodialysis or ECMO and explores the treatment of caffeine intoxication with a literature review.

Heterogeneity and bias in animal models of lipid emulsion therapy: a systematic review and meta-analysis

INTRODUCTION

Clinicians utilize lipid emulsion to treat local anesthetic toxicity and non-local anesthetic toxicities, a practice supported by animal experimentation and clinical experience. Prior meta-analysis confirmed a mortality benefit of lipid emulsion in animal models of local anesthetic toxicity but the benefit of lipid emulsion in models of non-local anesthetic toxicity remains unanswered. Further, swine suffer an anaphylactoid reaction from lipid emulsions calling into question their role as a model system to study lipid, so we examined swine and non-swine dependent outcomes in models of intravenous lipid emulsion.

METHODS

We conducted a systematic review and meta-analysis examining the use of lipid emulsion therapy in animal models of cardiac toxicity. We quantified mortality using a random-effects odds-ratio method. Secondary outcomes included survival in the following subgroups: local-anesthetic systemic toxicity, non-local anesthetic toxicity, swine-based models, and non-swine models (e.g., rat, rabbit and dog). We assessed for heterogeneity with Cochran's Q and I². We examined bias with Egger's test & funnel plot analysis.

RESULTS

Of 2784 references screened, 58 met criteria for inclusion. Treatment with lipid emulsion reduced chance of death in all models of toxicity with an odds ratio of death of 0.26 (95% CI 0.16-0.44, Z-5.21, p < 0.00001, Cohen's-d = 0.72, n = 60). Secondary outcomes confirmed a reduced chance of death in models of local anesthetic toxicity (OR 0.16 {95% CI 0.1-0.33}) and non-local anesthetic toxicity (OR 0.43 {95% CI 0.22-0.83}). Heterogeneity (Cochran's Q 132 {df = 59, p < 0.01}, I ² = 0.55) arose primarily from animal-model and disappeared (I ² < = 0.12) when we analyzed swine and non-swine subgroups independently. Swine only benefited in models of local anesthetic toxicity (OR 0.28 {95% CI 0.11-0.7}, p = 0.0033) whereas non-swine models experienced a homogeneous benefit across all toxins (OR 0.1 {95% CI 0.06-0.16}, p < 0.00001). Egger's test identified risk of bias with outliers on funnel plot analysis.

DISCUSSION

Lipid emulsion therapy reduces mortality in animal models of toxicity. Heterogeneity arises from the animal-model used. Swine only benefit in models of local anesthetic toxicity, potentially due to lipid dose, experimental design or swine's anaphylactoid reaction to lipid. Outlier analysis reinforced the need for appropriate dosing of lipid emulsion along with airway management and chest compressions in the setting of cardiac arrest.

Propofol suppresses ventricular arrhythmias: a case report of acute caffeine intoxication

Background

Caffeine is widely used as a stimulant drug throughout the world, and fatal arrhythmia is a known side‐effect. We experienced a patient with caffeine intoxication causing fatal arrhythmias who was successfully treated with the infusion of propofol.

Case Presentation

A 27‐year‐old woman was transferred to our hospital with nausea and poor general condition after intentional ingestion of 23.2 g of caffeine tablets. She was in cardiac arrest due to ventricular fibrillation just before hospital arrival. Advanced life support including defibrillation was started immediately, and we succeeded in resuscitating her 23 min later. Although she suffered from polymorphic ventricular premature beats and frequent transition to ventricular fibrillation, propofol administration converted her from a ventricular arrhythmia to sinus rhythm.

Conclusion

We report this case focusing on the cardiovascular effects of propofol and the lipid sink phenomenon. As a result, propofol could have the potential to suppress ventricular arrhythmias.

Advances of Nano-Structured Extended-Release Local Anesthetics

Extended-release local anesthetics (LAs) have drawn increasing attention with their promising role in improving analgesia and reducing adverse events of LAs. Nano-structured carriers such as liposomes and polymersomes optimally meet the demands of/for extended-release, and have been utilized in drug delivery over decades and showed satisfactory results with extended-release. Based on mature technology of liposomes, EXPAREL, the first approved liposomal LA loaded with bupivacaine, has seen its success in an extended-release form. At the same time, polymersomes has advances over liposomes with complementary profiles, which inspires the emergence of hybrid carriers. This article summarized the recent research successes on nano-structured extended-release LAs, of which liposomal and polymeric are mainstream systems. Furthermore, with continual optimization, drug delivery systems carry properties beyond simple transportation, such as specificity and responsiveness. In the near future, we may achieve targeted delivery and controlled-release properties to satisfy various analgesic requirements.

A new alternative for intravenous lipid emulsion 20% w/w from superolein oil and its effect on lipid and liver profiles in an animal model

PURPOSE

Intravenous lipid emulsion (IVLE) was first used to prevent essential fatty acids deficiency. IVLE with α-tocopherol was reported to provide protection against parenteral nutrition-associated liver disease. This study aims to determine the optimal parameters and conditions in developing a physically stable IVLE from superolein palm oil (SoLE 20%) and its effect on lipid and liver profiles in an animal model.

METHODS

SoLE 20% was prepared using superolein oil and MCT oil (1:1), stabilized with egg lecithin and homogenized using a high pressure homogenizer. Mean droplet size was used as the response variable and was measured using laser diffraction and dynamic light scattering method. Physical stability at 4 °C, 25 °C and 40 °C storage temperatures were determined based on particle size and distribution, polydispersity index, zeta potential, viscosity, vitamin E contents and pH. Sterility and pyrogenicity were also investigated. Rabbits were administered with 1.0 g/kg SoLE 20% for 5 h and repeated daily for 3 days to investigate its effect on blood lipid and liver enzymes profile.

RESULTS

SoLE 20% was succesfully prepared using the optimized parameters of 800 psi, 7 cycles and 1.2 g lecithin. The IVLE prepared had a particle size of 252.60 ± 4.88 nm and was physically stable for 4 weeks at different storage temperatures. SoLE 20% had a high content of natural vitamin E, remained sterile and pyrogen free. It was also safe for intravenous administration and did not alter the blood lipid (p > 0.05) and liver enzymes profiles (p > 0.05) of the rabbits.

CONCLUSION

The optimal parameters to develop a stable superolein based IVLE are 800 psi homogenization pressure, 7 homogenization cycles and using 1.2 g lecithin as the emulsifier. SoLE 20% is safe for intravenous administration and does not significantly alter lipid and liver enzymes profiles of the rabbits.

Should Cytochrome P450 Inducers be Used to Accelerate Clearance of Brodifacoum from Poisoned Patients?

A recent multi-state outbreak of life-threatening bleeding following inhalation of synthetic cannabinoids has been attributed to contamination with the long-acting anticoagulant rodenticide (LAAR) brodifacoum, a second-generation, highly potent, long-acting derivative of the commonly used blood thinner warfarin. While long-term treatment with high-dose vitamin K1 restores coagulation, it does not affect brodifacoum metabolism or clearance, and, consequently, brodifacoum remains in the human body for several months, thereby predisposing to risk of bleeding recurrence and development of coagulation-independent injury in extrahepatic tissues and fetuses. This has prompted the evaluation of pharmacological measures that accelerate brodifacoum clearance from poisoned patients. Since the induction of certain cytochrome P450 (CYP) enzymes accelerates warfarin metabolism, using CYP inducers, such as phenobarbital, to accelerate brodifacoum clearance seems plausible. However, unlike warfarin, brodifacoum does not undergo significant metabolism in the liver, nor have the effects of phenobarbital on vitamin K1 metabolism been previously determined. In addition, the safety of phenobarbital in brodifacoum-poisoned patients has not been established. Therefore, we propose that CYP inducers should not be used to accelerate the clearance of brodifacoum from poisoned patients, but that alternative approaches such as reducing enterohepatic recirculation of brodifacoum, or using lipid emulsions to scavenge brodifacoum throughout the body, be considered.

Lipid emulsion in local anesthetic toxicity

PURPOSE OF REVIEW

Enthusiasm for regional anesthesia has been driven by multimodal benefits to patient outcomes. Despite widespread awareness and improved techniques (including the increasing use of ultrasound guidance for block placement), intravascular sequestration and the attendant risk of local anesthetic systemic toxicity (LAST) remains. Intravenous lipid emulsion (ILE) for the treatment of LAST has been endorsed by anesthetic regulatory societies on the basis of animal study and human case report data. The accumulated mass of reporting now permits objective interrogation of published literature.

RECENT FINDINGS

Although incompletely elucidated the mechanism of action for ILE in LAST seemingly involves beneficial effects on initial drug distribution (i.e., pharmacokinetic effects) and positive cardiotonic and vasoactive effects (i.e., pharmacokinetic effects) acting in concert. Recent systematic review by collaborating international toxicologic societies have provided reserved endorsement for ILE in bupivacaine-induced toxicity, weak support for ILE use in toxicity from other local anesthetics, and largely neutral recommendation for all other drug poisonings. Work since publication of these recommendations has concluded that there is a positive effect on survival for ILE when animal models of LAST are meta-analyzed and evidence of a positive pharmacokinetic effect for lipid in human models of LAST.

SUMMARY

Lipid emulsion remains first-line therapy (in conjunction with standard resuscitative measures) in LAST. Increasing conjecture as to the clinical efficacy of ILE in LAST, however, calls for high-quality human data to refine clinical recommendations.

Lipid Emulsion Inhibits Apoptosis Induced by a Toxic Dose of Verapamil via the Delta-Opioid Receptor in H9c2 Rat Cardiomyoblasts

The goals of this study were to investigate the effects of lipid emulsion (LE) on apoptosis induced by a toxic dose of verapamil in H9c2 cells and to elucidate the associated cellular mechanism. The effects of LE alone and combined with an inhibitor on the decreases in cell counts and viability induced by verapamil and diltiazem were examined using the MTT assay. The effects of verapamil alone, combined LE and verapamil treatment, and combined inhibitor, LE and verapamil treatment on cleaved caspase-3, caspase-8 and Bax expression, were examined using Western blotting. The effects of verapamil alone and combined with LE on the number of TUNEL-positive H9c2 cells were also examined. LE attenuated the decreases in cell counts and viability induced by verapamil and diltiazem. However, the magnitude of the LE-mediated attenuation of decreased cell viability was enhanced by verapamil compared with diltiazem treatment. Naloxone, naltrindole hydrochloride, LY294002 and MK-2206 inhibited the LE-mediated attenuation of increased cleaved caspase-3 and caspase-8 expression induced by verapamil. LE attenuated the increase in the number of TUNEL-positive cell induced by verapamil. These results suggest that LE attenuates apoptosis induced by verapamil via activation of the delta-opioid receptor, phosphoinositide 3-kinase and Akt.

Lipid Emulsion for Treating Local Anesthetic Systemic Toxicity

Lipid emulsion has been shown to be an effective treatment for systemic toxicity induced by local anesthetics, which is reflected in case reports. A systemic review and meta-analysis confirm the efficacy of this treatment. Investigators have suggested mechanisms associated with the lipid emulsion-mediated recovery of cardiovascular collapse caused by local anesthetic systemic toxicity; these mechanisms include lipid sink, a widely accepted theory in which highly soluble local anesthetics (particularly bupivacaine) are absorbed into the lipid phase of plasma from tissues (e.g., the heart) affected by local-anesthetic-induced toxicity; enhanced redistribution (lipid shuttle); fatty acid supply; reversal of mitochondrial dysfunction; inotropic effects; glycogen synthase kinase-3β phosphorylation associated with inhibition of the mitochondrial permeability transition pore opening; inhibition of nitric oxide release; and reversal of cardiac sodium channel blockade. The current review includes the following: 1) an introduction, 2) a list of the proposed mechanisms, 3) a discussion of the best lipid emulsion treatment for reversal of local anesthetic toxicity, 4) a description of the effect of epinephrine on lipid emulsion-mediated resuscitation, 5) a description of the recommended lipid emulsion treatment, and 6) a conclusion.

The Knowledge of Eye Physicians on Local Anesthetic Toxicity and Intravenous Lipid Treatment: Questionnaire Study

Objectives

To evaluate the knowledge of ophthalmologists regarding local anesthesia toxicity syndrome (LATS) and intravenous lipid emulsion used in treatment, and to raise awareness of this issue.

Materials and Methods

A questionnaire comprising 14 questions about demographics, local anesthesia (LA) use, toxicity, and treatment methods was administered to ophthalmologists at different hospitals.

Results

The study included 104 ophthalmologists (25% residents, 67.3% specialists, 7.7% faculty members) with a mean age of 35.71±6.53 years. The highest number of participants was from state hospitals (65.4%), and 34.6% of the physicians had been working in ophthalmology for more than 10 years. Seventy-six percent of the participants reported using LA every day or more than twice a week, but 56.7% had received no specific training on this subject. No statistically significant difference was observed between different education levels and the rates of training (p=0.419). Bupivacaine was the most preferred LA and the majority of respondents (97.1%) did not use a test dose. Allergy (76%) and hypotension (68.3%) were the most common responses for early findings of LATS, while cardiac arrest (57.4%) and hepatotoxicity (56.4%) were given for late findings. The most common responses concerning the prevention of LATS included monitorization (72.4%) and use of appropriate doses (58.2%). Symptomatic treatment was selected by 72.4% of respondents and cardiopulmonary resuscitation and antihistamine treatment by 58.8%. Of the ophthalmologists in the study, 62.5% had never encountered LATS. The use of 20% intravenous lipid emulsion therapy for toxicity was known by 65% of the physicians, but only 1 participant stated having used it previously.

Conclusion

The importance of using 20% lipid emulsion in LATS treatment and having it available where LA is administered must be emphasized, and there should be compulsory training programs for ophthalmologists on this subject.

Lipid emulsion alleviates the vasodilation and mean blood pressure decrease induced by a toxic dose of verapamil in isolated rat aortae and an in vivo rat model

This study aimed to examine the effects of lipid emulsion on the vasodilation and cardiovascular depression induced by toxic doses of calcium channel blockers. The effects of lipid emulsion on the vasodilation induced by bepridil, verapamil, nifedipine, and diltiazem were investigated in isolated endothelium-denuded rat aortae. The effect of lipid emulsion on the comparable hemodynamic depression induced by the continuous infusion of a toxic dose of either verapamil or diltiazem was examined in an in vivo rat model. The results showed the following decreasing order for the magnitude of lipid emulsion-mediated inhibition of vasodilation: bepridil, verapamil, nifedipine, and diltiazem. Lipid emulsion (0.5–2%) reversed the vasodilation induced by a toxic dose of verapamil, whereas only a higher concentration (2%) reversed the vasodilation induced by a toxic dose of diltiazem. Pretreatment with lipid emulsion alleviated the systolic and mean blood pressure decreases induced by a toxic dose of verapamil, whereas it had no effect on the decrease induced by diltiazem. Taken together, these results suggest that lipid emulsion alleviates the severe vasodilation and systolic blood pressure decrease induced by a toxic dose of verapamil, and this alleviation appears to be associated with the relatively high lipid solubility of verapamil.

Amitriptyline-induced ventricular tachycardia: a case report

Background

In Bangladesh, each emergency physician faces amitriptyline overdose nearly a day. An acute cardiovascular complication, one of the worst complications is mainly responsible for the mortality in tricyclic overdose. Recently, we managed ventricular tachycardia in a young female presented with an impaired consciousness 10 h after intentionally ingesting 2500 mg amitriptyline. Here, we report it, discuss how the electrocardiography is vital to acknowledge and predict it and its’ complications and also the recent update of the management of it.

Case presentation

A young married Bangladeshi-Bengali girl, 25-year-old, having a history of disharmony with her husband, came with an impaired consciousness after intentionally ingesting 2500 mg amitriptyline about 10 h before arrival. There was blood pressure 140/80 mmHg, heart rate 140 beats-per-min, temperature 103 °F, Glasgow coma scale 10/15, wide complex tachycardia with QRS duration of 178 ms in electrocardiography, blood pH 7.36. Initially, treated with 100 ml 8.4% sodium bicarbonate. After that, QRS duration came to 100 ms in electrocardiography within 10 min of infusion. To maintain the pH 7.50–7.55 over the next 24 h, the infusion of 8.4% sodium bicarbonate consisting of 125 ml dissolved in 375 ml normal saline was started and titrated according to the arterial blood gas analysis. Hence, a total dose of 600 mmol sodium bicarbonate was given over next 24 h. In addition to this, gave a 500 ml intravenous lipid emulsion over 2 h after 24 h of admission as she did not regain her consciousness completely. Afterward, she became conscious, though, in electrocardiography, ST/T wave abnormality persisted. So that, we tapered sodium bicarbonate infusion slowly and stopped it later. At the time of discharge, she was by heart rate 124/min, QRS duration 90 ms in electrocardiogram along with other normal vital signs.

Conclusion

Diagnosis of amitriptyline-induced ventricular tachycardia is difficult when there is no history of an overdose obtained. Nevertheless, it should be performed in the clinical background and classic electrocardiographic changes and wise utilization of sodium bicarbonate, intravenous lipid emulsion, and anti-arrhythmic drugs may save a life.

Venlafaxine intoxication with development of takotsubo cardiomyopathy: successful use of extracorporeal life support, intravenous lipid emulsion and CytoSorb®

We describe a young patient who ingested 18 g (240 times the daily therapeutic dose) of venlafaxine in a suicide attempt. She developed severe cardiomyopathy in a takotsubo distribution causing cardiogenic shock and multi-organ dysfunction syndrome (MODS). She was successfully treated with intravenous lipid emulsion (ILE), extracorporeal life support (ECLS) and CytoSorb®. This is remarkable as, to the best of the authors' knowledge, this is the highest amount of venlafaxine intake seen in the literature with a nonfatal outcome.

L-carnitine reduces susceptibility to bupivacaine-induced cardiotoxicity: an experimental study in rats

BACKGROUND

The primary aim of this study was to evaluate the effect of acute administration of L-carnitine 100 mg·kg^-1 iv on susceptibility to bupivacaine-induced cardiotoxicity in rats.

METHODS

In the first of two experiments, L-carnitine 100 mg·kg^-1 iv (n = 10) or saline iv (n = 10) was administered to anesthetized and mechanically ventilated Sprague-Dawley rats following which an infusion of bupivacaine 2.0 mg·kg^-1·min^-1 iv was given until asystole occurred. The primary outcome was the probability of survival. Secondary outcomes included times to asystole, first dysrhythmia, and to 50% reductions in heart rate (HR) and mean arterial pressure (MAP). To determine whether the same dose of L-carnitine is effective in treating established bupivacaine cardiotoxicity, we also conducted a second experiment in which bupivacaine 20 mg·kg^-1 iv was infused over 20 sec. Animals (n = 10 per group) received one of four iv treatments: 30% lipid emulsion 4.0 mL·kg^-1, L-carnitine 100 mg·kg^-1, 30% lipid emulsion plus L-carnitine, or saline. The primary outcome was the return of spontaneous circulation (ROSC) during resuscitation.

RESULTS

In the first study, L-carnitine 100 mg·kg^-1 increased the probability of survival during bupivacaine infusion (hazard ratio, 12.0; 95% confidence interval, 3.5 to 41.5; P < 0.001). In L-carnitine-treated animals, the times to asystole, first dysrhythmia, and to 50% reductions in HR and MAP increased by 33% (P < 0.001), 65% (P < 0.001), 71% (P < 0.001), and 63% (P < 0.001), respectively. In the second study, no animal in the control or L-carnitine alone groups achieved ROSC when compared with the lipid emulsion groups (P < 0.01).

CONCLUSION

These findings suggest that acute administration of L-carnitine 100 mg·kg^-1 decreases susceptibility to bupivacaine cardiotoxicity, but is ineffective during resuscitation from bupivacaine-induced cardiac arrest.

Lipid Therapy for Intoxications

This review discusses the use of intravenous lipid emulsion (ILE) in the treatment of intoxications with lipophilic agents in veterinary medicine. Despite growing scientific evidence that ILE has merit in the treatment of certain poisonings, there is still uncertainty on the optimal composition of the lipid emulsion, the dosing, the mechanism of action, and the efficacy. Therefore, a critical view of the clinician on the applicability of this modality in intoxications is still warranted. The use of ILE therapy is advocated as an antidote in cases of intoxications with some lipophilic substances.

Knowledge of the Research Assistants Regarding Local Anaesthetics and Toxicity

OBJECTIVE

Cardiovascular system depression, respiratory arrest, coma, convulsions, loss of consciousness, muscle twitching, blurred vision, vertigo, dizziness and numbness of the tongue can be seen in local anaesthetic toxicity. Treatment includes 20% lipid solutions, airway control, symptomatic treatment for arrhythmia and convulsions. The aim of this study is to present the knowledge of research assistants, who used local anaesthetics in daily practice, regarding these medications and toxicity treatment and to raise awareness.

METHODS

The questionnaire comprising 20 questions was administered to 115 research assistants who worked at different specialities in our hospital.

RESULTS

One hundred and two (88.6%) research assistants answered the questionnaire. Participants' mean age was 28.93 years. Most of them were from the Emergency Department (15.7%). A total of 40.6% of participants worked for 2-5 years at their departments. Local anaesthetics were used in daily practice for 44.4% of them, but 70.3% of them had not been educated about local anaesthetics. Research assistants from anaesthesiology and reanimation participated at a significantly higher rate than other departments (76.9%), in terms of training programs regarding local anaesthetics. While the most popular answers about early toxicity symptoms were anaphylaxis (12.7%) and arrthymia (12.7%), late toxicity was hepatotoxicity (10.8%). However, 87.9% of participants had never encountered local anaesthetic toxicity. The great majority of participants had never heard of lipid therapy (67.4%), and those who were aware had heard it from their trainers (52.2%). Although lipid solution was available in our hospital, only 8.4% of participants knew this.

CONCLUSION

We believe that additional training programs regarding local anaesthetics and toxicity are needed.

Intralipid in acute caffeine intoxication: a case report

Caffeine is arguably the most widely used stimulant drug in the world. Here we describe a suicide attempt involving caffeine overdose whereby the patient's severe intoxication was successfully treated with the prompt infusion of Intralipid. A 19-year-old man was found in an agitated state at home by the volunteer emergency team about 1 h after the intentional ingestion of 40 g of caffeine (tablets). His consciousness decreased rapidly, followed quickly by seizures, and electrocardiographic monitoring showed ventricular fibrillation. Advanced life support maneuvers were started immediately, with the patient defibrillated 10 times and administered 5 mg epinephrine in total and 300 + 150 mg of amiodarone (as well as lidocaine and magnesium sulfate). The cardiac rhythm eventually evolved to asystole, necessitating the intravenous injection of epinephrine to achieve the return of spontaneous circulation. However, critical hemodynamic instability persisted, with the patient's cardiac rhythm alternating between refractory irregular narrow complex tachycardia and wide complex tachycardia associated with hypotension. In an attempt to restore stability we administered three successive doses of Intralipid (120 + 250 + 100 mg), which successfully prevented a severe cardiovascular collapse due to a supra-lethal plasma caffeine level (>120 mg/L after lipid emulsion). The patient survived without any neurologic complications and was transferred to a psychiatric ward a few days later. The case emphasizes the efficacy of intravenous lipid emulsion in the resuscitation of patients from non-local anesthetic systemic toxicity. Intralipid appears to act initially as a vehicle that carries the stimulant drug away from heart and brain to less well-perfused organs (scavenging mechanism) and then, with a sufficient drop in the caffeine concentration, possibly as a tonic to the depressed heart.

The emerging threat of superwarfarins: history, detection, mechanisms, and countermeasures

Superwarfarins were developed following the emergence of warfarin resistance in rodents. Compared to warfarin, superwarfarins have much longer half-lives and stronger affinity to vitamin K epoxide reductase and therefore can cause death in warfarin-resistant rodents. By the mid-1970s, the superwarfarins brodifacoum and difenacoum were the most widely used rodenticides throughout the world. Unfortunately, increased use was accompanied by a rise in accidental poisonings, reaching >16,000 per year in the United States. Risk of exposure has become a concern since large quantities, up to hundreds of kilograms of rodent bait, are applied by aerial dispersion over regions with rodent infestations. Reports of intentional use of superwarfarins in civilian and military scenarios raise the specter of larger incidents or mass casualties. Unlike warfarin overdose, for which 1-2 days of treatment with vitamin K is effective, treatment of superwarfarin poisoning with vitamin K is limited by extremely high cost and can require daily treatment for a year or longer. Furthermore, superwarfarins have actions that are independent of their anticoagulant effects, including both vitamin K-dependent and -independent effects, which are not mitigated by vitamin K therapy. In this review, we summarize superwarfarin development, biology and pathophysiology, their threat as weapons, and possible therapeutic approaches.

The possible role of intravenous lipid emulsion in the treatment of chemical warfare agent poisoning

Organophosphates (OPs) are cholinesterase inhibitors that lead to a characteristic toxidrome of hypersecretion, miosis, dyspnea, respiratory insufficiency, convulsions and, without proper and early antidotal treatment, death. Most of these compounds are highly lipophilic. Sulfur mustard is a toxic lipophilic alkylating agent, exerting its damage through alkylation of cellular macromolecules (e.g., DNA, proteins) and intense activation of pro-inflammatory pathways. Currently approved antidotes against OPs include the peripheral anticholinergic drug atropine and an oxime that reactivates the inhibited cholinesterase. Benzodiazepines are used to stop organophosphate-induced seizures. Despite these approved drugs, efforts have been made to introduce other medical countermeasures in order to attenuate both the short-term and long-term clinical effects following exposure. Currently, there is no antidote against sulfur mustard poisoning. Intravenous lipid emulsions are used as a source of calories in parenteral nutrition. In recent years, efficacy of lipid emulsions has been shown in the treatment of poisoning by fat-soluble compounds in animal models as well as clinically in humans. In this review we discuss the usefulness of intravenous lipid emulsions as an adjunct to the in-hospital treatment of chemical warfare agent poisoning.