Treatment of Local Anesthetic Systemic Toxicity (LAST):

Prevention of persistent pain with lidocaine infusions in breast cancer surgery (PLAN): study protocol for a multicenter randomized controlled trial

BACKGROUND

Persistent pain is a common yet debilitating complication after breast cancer surgery. Given the pervasive effects of this pain disorder on the patient and healthcare system, post-mastectomy pain syndrome (PMPS) is becoming a larger population health problem, especially as the prognosis and survivorship of breast cancer increases. Interventions that prevent persistent pain after breast surgery are needed to improve the quality of life of breast cancer survivors. An intraoperative intravenous lidocaine infusion has emerged as a potential intervention to decrease the incidence of PMPS. We aim to determine the definitive effects of this intervention in patients undergoing breast cancer surgery.

METHODS

PLAN will be a multicenter, parallel-group, blinded, 1:1 randomized, placebo-controlled trial of 1,602 patients undergoing breast cancer surgery. Adult patients scheduled for a lumpectomy or mastectomy will be randomized to receive an intravenous 2% lidocaine bolus of 1.5 mg/kg with induction of anesthesia, followed by a 2.0 mg/kg/h infusion until the end of surgery, or placebo solution (normal saline) at the same volume. The primary outcome will be the incidence of persistent pain at 3 months. Secondary outcomes include the incidence of pain and opioid consumption at 1 h, 1-3 days, and 12 months after surgery, as well as emotional, physical, and functional parameters, and cost-effectiveness.

DISCUSSION

This trial aims to provide definitive evidence on an intervention that could potentially prevent persistent pain after breast cancer surgery. If this trial is successful, lidocaine infusion would be integrated as standard of care in breast cancer management. This inexpensive, widely available, and easily administered intervention has the potential to reduce pain and suffering in an already afflicted patient population, decrease the substantial costs of chronic pain management, potentially decrease opioid use, and improve the quality of life in patients.

TRIAL REGISTRATION

This trial has been registered on clinicaltrials.gov (NCT04874038, Dr. James Khan. Date of registration: May 5, 2021).

Intravenous lipid emulsion for local anaesthetic systemic toxicity in pregnant women: a scoping review

BACKGROUND

Local anaesthetic systemic toxicity (LAST) is a rare but life-threatening complication that can occur after local anaesthetic administration. Various clinical guidelines recommend an intravenous lipid emulsion as a treatment for local anaesthetic-induced cardiac arrest. However, its therapeutic application in pregnant patients has not yet been established. This scoping review aims to systematically identify and map the evidence on the efficacy and safety of intravenous lipid emulsion for treating LAST during pregnancy.

METHOD

We searched electronic databases (Medline, Embase and Cochrane Central Register Controlled Trials) and a clinical registry (lipidrescue.org) from inception to Sep 30, 2022. No restriction was placed on the year of publication or the language. We included any study design containing primary data on obstetric patients with signs and symptoms of LAST.

RESULTS

After eliminating duplicates, we screened 8,370 titles and abstracts, retrieving 41 full-text articles. We identified 22 women who developed LAST during pregnancy and childbirth, all presented as case reports or series. The most frequent causes of LAST were drug overdose and intravascular migration of the epidural catheter followed by wrong-route drug errors (i.e. intravenous anaesthetic administration). Of the 15 women who received lipid emulsions, all survived and none sustained lasting neurological or cardiovascular damage related to LAST. No adverse events or side effects following intravenous lipid emulsion administration were reported in mothers or neonates. Five of the seven women who did not receive lipid emulsions survived; however, the other two died.

CONCLUSION

Studies on the efficacy and safety of lipids in pregnancy are scarce. Further studies with appropriate comparison groups are needed to provide more robust evidence. It will also be necessary to accumulate data-including adverse events-to enable clinicians to conduct risk-benefit analyses of lipids and to facilitate evidence-based decision-making for clinical practice.

2023 American Heart Association Focused Update on the Management of Patients With Cardiac Arrest or Life-Threatening Toxicity Due to Poisoning: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

In this focused update, the American Heart Association provides updated guidance for resuscitation of patients with cardiac arrest, respiratory arrest, and refractory shock due to poisoning. Based on structured evidence reviews, guidelines are provided for the treatment of critical poisoning from benzodiazepines, β-adrenergic receptor antagonists (also known as β-blockers), L-type calcium channel antagonists (commonly called calcium channel blockers), cocaine, cyanide, digoxin and related cardiac glycosides, local anesthetics, methemoglobinemia, opioids, organophosphates and carbamates, sodium channel antagonists (also called sodium channel blockers), and sympathomimetics. Recommendations are also provided for the use of venoarterial extracorporeal membrane oxygenation. These guidelines discuss the role of atropine, benzodiazepines, calcium, digoxin-specific immune antibody fragments, electrical pacing, flumazenil, glucagon, hemodialysis, hydroxocobalamin, hyperbaric oxygen, insulin, intravenous lipid emulsion, lidocaine, methylene blue, naloxone, pralidoxime, sodium bicarbonate, sodium nitrite, sodium thiosulfate, vasodilators, and vasopressors for the management of specific critical poisonings.

LC-MS/MS assisted biomonitoring of ropivacaine and 3-OH-ropivacaine after plane block anesthesia for cardiac device implantation

Introduction: Ropivacaine is a popular local anesthetic used for regional anesthesia or for pain management. Although designed as an enantiomerically pure drug, an aspect that reduces the adverse effects, its toxicological effects are still a risk. As such, biomonitoring to assure appropriate dosage and bioavailability are essential to avoid complications during or post-surgery. Methods: The study focused on developing a sensitive, selective, and accurate liquid chromatography-mass spectrometry (LCMS/MS) method which facilitates the biomonitoring of ropivacaine and its main metabolite in plasma after regional anesthesia using ropivacaine. Results and Discussion: The method was validated with regards to all relevant parameters, such as sensitivity, selectivity, accuracy, precision, and the effect of sample matrix. The method was successfully used in a pilot study, which included one patient undergoing plane block anesthesia for cardiac device implantation. The results showed the method is appropriate for its intended purpose and could even be used in other, similar applications.

Anesthesia for office-based facial plastic surgery procedures

Objective

The objective of this study is to provide a state-of-the-art review on the use of anesthetics for in-office facial plastic procedures.

Methods

A search was performed on PubMed, Embase, Web of Science, and Cochrane Review using the keywords "anesthesia," "office-based procedures," "local anesthesia," "facial plastics," "oral sedation," "moderate sedation," and "deep sedation."

Results and Conclusions

Over the past few decades, the shift toward in-office invasive procedures has increased patient convenience and decreased hospital resource utilization. Many tools exist to reduce patient anxiety and discomfort in an office-based setting. With proper patient selection and technique, facial plastic surgeons can adequately anesthetize patients to perform Mohs reconstruction, cutaneous excisions, blepharoplasty, face-lifts, and other in-office procedures.

İnfraklaviküler ve interskalen bloğun önkol oksijenasyonuna etkisi: randomize kontrollü bir çalışma

Amaç: Ultrasonografi görüntüleme (USG) eşliğinde yapılan infraklaviküler blok (İKB) ve interskalen blok (İSB), üst ekstremite ameliyatlarında en sık kullanılan brakiyal pleksus blok teknikleridir. Bu blokların uygulanmasından sonra sempatik blokaj oluştuğu ve blokajın neden olduğu vazodilatasyon ile kan akımının arttığı bilinmektedir. Bu çalışmada USG ile birlikte uygulanan İKB ve İSB'nin önkol doku oksijenasyonuna etkisinin karşılaştırılması amaçlandı. Gereç ve Yöntem: Bu çalışmaya elektif veya acil kol, dirsek veya önkol cerrahisi planlanan 18-65 yaş arası ASA I-III risk gruplarına ait yüz dört hasta dahil edildi. Hastalar iki gruba ayrıldı: Grup İKB ve Grup İSB. Bazal hemodinamik ölçümlere ek olarak, blok öncesi ve blok tamamlandıktan sonra 10., 20. ve 30. dakikalarda Perfüzyon indeksi(PI), ortalama akım hızı(TAV), brakiyal arter çapı(BAÇ), brakiyal arter alanı(BAA), brakiyal arter atım akımı (BF) ve doku oksijen satürasyonu(rSO2) verileri önceden kaydedildi. Bulgular: Grup İSB ve Grup İKB'deki hastaların demografik verileri karşılaştırıldı, gruplar arasında anlamlı fark saptanmadı. PI ve rSO2 değerlerindeki artış yüzdelerinin zamana göre dağılımı incelendiğinde, gruplar arasında anlamlı farklılıklar bulundu. 0. dakika ile 10., 20. ve 30. dakikalar arasında BF, TAV, BAA ve BAÇ değerlerindeki yüzde artışlarında anlamlı fark yoktu. Grup İSB'de 8 hastada (%15) Horner sendromu, 3 hastada (%5) ani ses kısıklığı gözlendi. Grup İKB'de komplikasyon gelişmedi. Sonuç: Bu çalışmada İKB ve İSB'nin önkol doku oksijenasyonu üzerindeki etkilerinin karşılaştırıldığı ve İKB'nin rSO2 ve PI değerlerini arttırdığı tespit edilmiştir.

Local anesthetic systemic toxicity: A narrative review for emergency clinicians

INTRODUCTION

Emergency clinicians utilize local anesthetics for a variety of procedures in the emergency department (ED) setting. Local anesthetic systemic toxicity (LAST) is a potentially deadly complication.

OBJECTIVE

This narrative review provides emergency clinicians with the most current evidence regarding the pathophysiology, evaluation, and management of patients with LAST.

DISCUSSION

LAST is an uncommon but potentially life-threatening complication of local anesthetic use that may be encountered in the ED. Patients at extremes of age or with organ dysfunction are at higher risk. Inadvertent intra-arterial or intravenous injection, as well as repeated doses and higher doses of local anesthetics are associated with greater risk of developing LAST. Neurologic and cardiovascular manifestations can occur. Early recognition and intervention, including supportive care and intravenous lipid emulsion 20%, are the mainstays of treatment. Using ultrasound guidance, aspirating prior to injection, and utilizing the minimal local anesthetic dose needed are techniques that can reduce the risk of LAST.

CONCLUSIONS

This focused review provides an update for the emergency clinician to manage patients with LAST.

Epinephrine and Dexamethasone as Adjuvants in Upper Extremity Peripheral Nerve Blocks in Pediatric Patients

Introduction: Regional anesthesia in children in recent years has been accepted worldwide. The increased interest in it is partly due to the use of ultrasonography which provides confidence and accuracy to the anesthesiologic team. Adjuvants are used to extend the duration of the sensory and motor blocking, limiting the cumulative dose of local anesthetics. The use of adjuvants in peripheral nerve blocks in the pediatric population is still under research. Aim: To observe the effect of epinephrine and dexamethasone as adjuvants to local anesthetics in peripheral upper extremity nerve blocks in pediatric patients. Materials and methods: The study included 63 patients, aged group 4-14 years, admitted to the University Clinic of Pediatric Surgery for surgical treatment of upper limb fractures in the period of January 2020 until March 2021. Patients were randomized into three groups, and all patients in the groups received analgo-sedation prior to peripheral nerve block. Patients in group 1 (21 patients) received supraclavicular, or interscalene block with 2 ml lidocaine 2% and bupivacaine 0.25% (max 2mg/kg) with a total volume of 0.5ml/kg. In group 2, the patients (21) received 25 μg of epinephrine in 2 ml of 2% solution of lidocaine and 0.25% bupivacaine (max 2 mg/kg) with a total volume of 0.5 ml/kg, and in group 3, the patients (21) received 2% lidocaine 2ml and 0.25% bupivacaine (max 2mg/kg) in combination with 2mg dexamethasone with a total volume of 0.5ml/kg. Results: Results showed that in patients in group 1, the average duration of the sensory block was 7 hours, while the duration of the motor block was 5 hours and 30 minutes. In group 2 (epinephrine), the durations of both sensory and motor block were prolonged for about 30 minutes on average compared to the first group. In group 3 (dexamethasone) the duration of the sensory and motor block was significantly longer compared with the first two groups (p<0.0001). Conclusion: Epinephrine and dexamethasone prolong the duration of action of local anesthetics in peripheral nerve blocks of the upper extremity in pediatric patients and thus reduce the need for analgesics in the postoperative period.

Mechanisms and Efficacy of Intravenous Lipid Emulsion Treatment for Systemic Toxicity From Local Anesthetics

Local anesthetics are widely used clinically for perioperative analgesia to achieve comfort in medical treatment. However, when the concentration of local anesthetics in the blood exceeds the tolerance of the body, local anesthetic systemic toxicity (LAST) will occur. With the development and popularization of positioning technology under direct ultrasound, the risks and cases of LAST associated with direct entry of the anesthetic into the blood vessel have been reduced. Clinical occurrence of LAST usually presents as a series of severe toxic reactions such as myocardial depression, which is life-threatening. In addition to basic life support (airway management, advanced cardiac life support, etc.), intravenous lipid emulsion (ILE) has been introduced as a treatment option in recent years and has gradually become the first-line treatment for LAST. This review introduces the mechanisms of LAST and identifies the clinical symptoms displayed by the central nervous system and cardiovascular system. The paper features the multimodal mechanism of LAST reversal by ILE, describes research progress in the field, and identifies other anesthetics involved in the resuscitation process of LAST. Finally, the review presents key issues in lipid therapy. Although ILE has achieved notable success in the treatment of LAST, adverse reactions and contraindications also exist; therefore, ILE requires a high degree of attention during use. More in-depth research on the treatment mechanism of ILE, the resuscitation dosage and method of ILE, and the combined use with other resuscitation measures is needed to improve the efficacy and safety of clinical resuscitation after LAST in the future.

Updates in our understanding of local anaesthetic systemic toxicity: a narrative review

Despite advances in clinical practice, local anaesthetic systemic toxicity continues to occur with the therapeutic use of local anaesthesia. Patterns of presentation have evolved over recent years due in part to the increasing use of ultrasound which has been demonstrated to reduce risk. Onset of toxicity is increasingly delayed, a greater proportion of clinical reports are secondary to fascial plane blocks, and cases are increasing where non-anaesthetist providers are involved. The evolving clinical context presents a challenge for diagnosis and requires education of all physicians, nurses and allied health professionals about these changing patterns and risks. This review discusses: mechanisms; prevention; diagnosis; and treatment of local anaesthetic systemic toxicity. The local anaesthetic and dose used, site of injection and block conduct and technique are all important determinants of local anaesthetic systemic toxicity, as are various patient factors. Risk mitigation is discussed including the care of at-risk groups, such as: those at the extremes of age; patients with cardiac, hepatic and specific metabolic diseases; and those who are pregnant. Advances in the changing clinical landscape with novel applications and settings for the use of local anaesthesia are also described. Finally, we signpost future directions to potentially improve the management of local anaesthetic systemic toxicity. The utility of local anaesthetics remains unquestionable in clinical practice, and thus maximising the safe and appropriate use of these drugs should translate to improvements in patient care.

Plastic Surgery Complications: A Review for Emergency Clinicians

The number of aesthetic surgical procedures performed in the United States is increasing rapidly. Over 1.5 million surgical procedures and over three million nonsurgical procedures were performed in 2015 alone. Of these, the most common procedures included surgeries of the breast and abdominal wall, specifically implants, liposuction, and subcutaneous injections. Emergency clinicians may be tasked with the management of postoperative complications of cosmetic surgeries including postoperative infections, thromboembolic events, skin necrosis, hemorrhage, pulmonary edema, fat embolism syndrome, bowel cavity perforation, intra-abdominal injury, local seroma formation, and local anesthetic systemic toxicity. This review provides several guiding principles for management of acute complications. Understanding these complications and approach to their management is essential to optimizing patient care.

[Stocktaking of local anesthetics 2020]

For decades local anesthetics have proven to be safe and effective drugs in the clinical practice, crucially promoting the enormous achievements in regional anesthesia. Meanwhile, it is a well-known fact that local anesthetics are much more than just "simple" sodium channel blockers. They also interact with numerous other ion channels and subcellular structures, enhancing nerve blockade and resulting in systemic "alternative" effects, which can sometimes even be clinically used. By the simultaneous administration of various adjuvants (e.g., opioids, corticosteroids and α₂-receptor agonists) attempts are made to prolong the time of action of local anesthetics after a single administration in order to achieve the best possible improvement in postoperative analgesia. In this context, ultralong-acting local anesthetics, such as liposomal bupivacaine, which at least theoretically can provide a sensory nerve block for several days, have been developed and clinically introduced. The coming years will show whether these approaches will develop into genuine alternatives to the personnel and cost-intensive continuous nerve blockades.Local anesthetic-induced systemic toxicity is meanwhile rare but still a potentially life-threatening event, frequently resulting from accidental intravascular injection or extensive systemic resorption. Consequently, slow and fractional application of these agents with intermittent aspiration helps to prevent toxic sequelae. If toxic symptoms occur, however, the intravenous infusion of 20% lipid solutions in addition to basic treatment measures can enhance the success of treatment.

Newer nerve blocks in pediatric surgery

PURPOSE OF THE REVIEW

The purpose of this manuscript is to provide a brief discussion of the current direction in pediatric regional anesthesia, highlighting both newer nerve blocks and techniques and traditional nerve blocks.

RECENT FINDINGS

The number of nerve blocks performed in pediatric patients continues to increase. This growth is likely related in part to the recent focus on perioperative multimodal analgesia, in addition to growing data demonstrating safety and efficacy in this patient population. Multiple studies by the Pediatric Regional Anesthesia Network (PRAN) and the French-Language Society of Pediatric Anesthesiologists (ADARPEF) have demonstrated lack of major complications and general overall safety with pediatric nerve blocks. The growing prevalence of ultrasound-guided regional anesthesia has not only improved the safety profile, but also increased the efficacy of both peripheral nerve blocks and perineural catheters.

SUMMARY

As the push for multimodal analgesia increases and the breadth of pediatric regional anesthesia continues to expand, further large prospective studies will be needed to demonstrate continued efficacy and overall safety.

Lipid emulsion therapy of local anesthetic systemic toxicity due to dental anesthesia

Local anesthetic systemic toxicity (LAST) refers to the complication affecting the central nervous system (CNS) and cardiovascular system (CVS) due to the overdose of local anesthesia. Its reported prevalence is 0.27/1000, and the representative symptoms range from dizziness to unconsciousness in the CNS and from arrhythmias to cardiac arrest in the CVS. Predisposing factors of LAST include extremes of age, pregnancy, renal disease, cardiac disease, hepatic dysfunction, and drug-associated factors. To prevent the LAST, it is necessary to recognize the risk factors for each patient, choose a safe drug and dose of local anesthesia, use vasoconstrictor , confirm aspiration and use incremental injection techniques. According to the treatment guidelines for LAST, immediate application of lipid emulsion plays an important role. Although lipid emulsion is commonly used for parenteral nutrition, it has recently been widely used as a non-specific antidote for various types of drug toxicity, such as LAST treatment. According to the recently published guidelines, 20% lipid emulsion is to be intravenously injected at 1.5 mL/kg. After bolus injection, 15 mL/kg/h of lipid emulsion is to be continuously injected for LAST. However, caution must be observed for >1000 mL of injection, which is the maximum dose. We reviewed the incidence, mechanism, prevention, and treatment guidelines, and a serious complication of LAST occurring due to dental anesthesia. Furthermore, we introduced lipid emulsion that has recently been in the spotlight as the therapeutic strategy for LAST.

Successful intralipid-emulsion treatment of local anesthetic systemic toxicity following ultrasound-guided brachial plexus block: case report

Background

Local anesthetic systemic toxicity (LAST) is a life-threatening complication that may follow application of LAs through various routes. Despite increasing usage of LA techniques in a large number of health-care settings, contemporary awareness of LAST and understanding of its management are inadequate.

Case presentation

We report two cases who suffered LAST following brachial plexus block for surgery on the upper extremity. The first patient received an ultrasound-guided supraclavicular block with 300 mg lidocaine (6 mg/kg) and 50 mg ropivacaine (1 mg/kg) in 25 mL without epinephrine, and the second patient received an ultrasound guided interscalene block with 200 mg lidocaine (4.5 mg/kg) and 45 mg ropivacaine (1 mg/kg) supplemented with epinephrine 1:200,000. Both patients presented with symptoms of central nervous and respiratory system depression, the first roughly 10 minutes after injection, and the second immediately after withdrawal of the needle. In both cases, thorough recovery was obtained using lipid-emulsion therapy.

Conclusion

The complication of LAST following ultrasound-guided brachial plexus block could be treated successfully applying the American Society of Regional Anesthesia and Pain Medicineprotocol of intravenous administration of lipid emulsion.

The Role of Intralipid Emulsion in the Rat Model of Digoxin Intoxication

Although the mechanism of action is not well known, intravenous lipid emulsion (ILE) has been shown to be effective in the treatment of lipophilic drug intoxications. It is thought that, ILE probably separates the lipophilic drugs from target tissue by creating a lipid-rich compartment in the plasma. The second theory is that ILE provides energy to myocardium with high-dose free fatty acids activating the voltage-gated calcium channels in the myocytes. In this study, effects of ILE treatment on digoxin overdose were searched in an animal model in terms of cardiac side effects and survival. Forty Sprague-Dawley rats were divided into five groups. As the pre-treatment, the groups were administered saline, ILE, DigiFab and DigiFab and ILE. Following that, digoxin was infused to all groups until death except the control group. First arrhythmia and cardiac arrest observation times were recorded. According to the results, there was no statistically significant difference among the group in terms of first arrhythmia time and cardiac arrest times. However, when the saline group compared with ILE-treated group separately, significant difference was observed. DigiFab, ILE or ILE-DigiFab treatment make no significant difference in terms of the first arrhythmia and cardiac arrest duration in digoxin-intoxicated rats. However, it is not possible to say that at the given doses, ILE treatment might be successful at least as a known antidote. The fact that the statistical significance between the two groups is not observed in the subgroup analysis, the study should be repeated with larger groups.

The Effects of Lidocaine with Epinephrine on Bupivacaine-Induced Cardiotoxicity

Objective

Bupivacaine, a local anaesthetic substance, is used as a regional-anaesthesia agent. Lidocaine, a sodium channel blocker, is used in combination with epinephrine for regional anaesthesia. We aimed to evaluate the effects of lidocaine with epinephrine (LE) at different doses on bupivacaine-induced cardiotoxicity in rats.

Methods

In our study, 24 Wistar albino rats were divided into four groups: I) Control; II) LE, 1 mg kg^-1; III) LE, 3 mg kg^-1 and IV) LE, 6 mg kg^-1. Intravenous bupivacaine was administered at a dose of 3 mg kg^-1 min^-1 to the anaesthetized rats in all groups until cardiac asystole was achieved. LE was administered at the doses of 1, 3 and 6 mg kg^-1 min^-1 using infusion, simultaneously with bupivacaine. The asystole time and 75% decrement time in mean arterial blood pressure (MABP) were determined. P-Q, Q-T and QRS intervals were measured using electrocardiography (ECG) recordings.

Results

LE significantly increased the asystole time and 75% decrement time in MABP at the doses of 3 and 6 mg kg^-1 compared to the control group (p<0.05) and significantly increased these values at the dose of 1 mg kg^-1 compared to the control and other treatment groups (p<0.05). LE abolished the prolongation of P-Q, Q-T and QRS intervals in ECG recordings at the dose of 1 mg kg^-1 (p<0.05).

Conclusion

These results reveal that LE has a protective effect against bupivacaine cardiotoxicity. In clinical application, the simultaneous application of LE and bupivacaine may reduce the risk of cardiotoxicity due to bupivacaine.

Introduction to surgical and perioperative clinical pharmacy for third-year pharmacy students: A pilot study of an elective course

INTRODUCTION

The objective of this study was to implement and assess an elective course that exposes pharmacy students to clinical pharmacy in the surgical and perioperative setting.

METHODS

A blended-design elective that included synchronous and asynchronous learning was developed and offered to third-year pharmacy students. Students' knowledge and perception regarding clinical topics in perioperative pharmacy was assessed using pre- and post-course assessments, online quizzes, a journal club, and course assignments. Knowledge of pharmacy operations was assessed using course assignments and reflective journal entries.

RESULTS

Pre- and post-course assessment improvement was seen in the categories of perioperative optimization of pharmacotherapy (29.1-70.1%, p=0.006), common surgical complications (45.8-91.7%, p = 0.001), and anesthetic agents (25-71.9%, p <0.001). Overall, the course was successful in increasing clinical pharmacy knowledge and was well received by students. Course evaluations were completed by 100% of students, and all rated the course as "excellent." Students demonstrated mastery of course content, though the course may not have provided optimal exposure to operating room/post-anesthesia care unit operations.

DISCUSSION AND CONCLUSIONS

Students agreed that the course was valuable and helped them develop new skills otherwise not developed by the curriculum; this conclusion was supported by objective assessment data. A team-teaching model allowed for minimal resources to operate the course. Moving forward, an early lecture addressing perioperative operations may supplement an area the course was lacking. Additionally, a longer duration of operating room shadowing may provide requested opportunities for observation of direct patient care.

Percutaneous Image-Guided Cryoablation in Vascular Anomalies

Understanding and management of vascular anomalies has always been intriguing. These disorders exhibit an expected pattern of clinical presentation and progression, and characteristic imaging findings. Significant progress in understanding and treating patients with vascular anomalies has been made in the past quarter century. Newer multidisciplinary domains for treating these disorders with medical drugs and less invasive image-guided or surgical procedures are constantly evolving. Vascular anomalies can exhibit aggressive tumor-like behavior resulting in recurrence or persistent symptoms after treatment. Thermal ablation has been widely used in tumor treatment. This has generated interest on using thermal ablation for treating vascular anomalies. Percutaneous image-guided cryoablation is increasingly used for this purpose as compared with other ablation technologies. Availability of small caliber cryoprobes and the ability to monitor the freeze zone in real time have made this an attractive option to interventional radiologists. These experiences are relatively new and limited. It is helpful to understand the emerging role of this technology in the treatment of vascular anomalies.

Successful use of lipid emulsion to resuscitate a foal after intravenous lidocaine induced cardiovascular collapse

BACKGROUND

Lipid emulsion has been reported to be effective for the treatment of local anaesthetic overdoses in rats, dogs and man.

OBJECTIVES

To describe the successful treatment of cardiovascular lidocaine toxicity in a foal with intravenous lipid administration.

STUDY DESIGN

Observational study: case report.

METHODS

An 8-month-old Arabian cross foal was anaesthetised for removal of the right alar fold and nasal plate. Anaesthesia was maintained with isoflurane in oxygen and lidocaine administered with a loading dose followed by a continuous rate infusion (CRI). The anaesthetic period was uneventful and 30 min before expected termination of the procedure lidocaine infusion was stopped. A sudden drop in mean arterial blood pressure was then observed. The ECG signal was lost, the end tidal CO₂ tension dropped from 40 to 10 mmHg, corneal reflex was absent and asystole diagnosed. Cardiopulmonary resuscitation manoeuvres were immediately initiated, but epinephrine and atropine were unsuccessfully administered. Lipid emulsion was administered and the heart rate and arterial blood pressure gradually returned to normal.

RESULTS

The foal recovered consciousness 3 h later, regained its sternal position, was responsive and 20 h later was able to stand up alone.

MAIN LIMITATIONS

It will be necessary to evaluate a greater number of cases to determine the effectiveness of lipids in foals intoxicated with lidocaine.

CONCLUSION

Intravenous lipid emulsion may be helpful in the treatment of potentially lethal cardiotoxicity attributable to lidocaine overdose in the foal.

The Utility of Peripheral Nerve Blocks in Interventional Radiology

OBJECTIVE

The aim of this article is to provide an overview of peripheral nerve blocks, the use of peripheral nerve block within and outside interventional radiology, and the complications of peripheral nerve block.

CONCLUSION

Interventional radiologists are often responsible for sedation and pain management in the majority of interventional radiology procedures. Peripheral nerve block is increasingly being used in interventional radiology.

Identifying and Managing Local Anesthetic Allergy in Dermatologic Surgery

BACKGROUND

Local anesthetic (LA) allergy is a concern for dermatologic surgeons given the large number of procedures performed yearly with LAs. Many patients also have anxiety about past or potential anesthesia allergy.

OBJECTIVE

This article will review the symptoms of IgE-mediated allergic reactions, the prevalence of IgE-mediated LA allergy, discuss common mimics of LA, and propose a practical approach for diagnostic and therapeutic options for LA allergy for the dermatologic surgeon in practice.

MATERIALS AND METHODS

A literature search of Pubmed using keywords "lidocaine," "local anesthetic," "hypersensitivity," and "allergy" was performed.

RESULTS

Amide anesthetics result in the most reports of true local anesthetic immediate hypersensitivity.

CONCLUSION

True IgE-mediated anaphylaxis to local anesthesia is very rare. Dermatologic surgeons should be aware of the symptoms of anesthetic allergy and its mimickers, as well as how to manage allergic reactions in their clinical practice.

Persistent gross lipemia and suspected corneal lipidosis following intravenous lipid therapy in a cat with permethrin toxicosis

OBJECTIVE

To describe the observation of persistent gross lipemia and suspected corneal lipidosis following intravenous lipid therapy (IVLT) in a cat with permethrin toxicosis.

CASE SUMMARY

A 5-year-old, spayed female, domestic short-haired cat with permethrin toxicosis was treated with a high dose of IVLT as an adjunct treatment when it remained severely obtunded following traditional supportive care. The cat received intravenous 20% lipid emulsion as a 1.5 mL/kg bolus given over 10 minutes followed by a constant rate infusion of 0.25 mL/kg/min for 2 hours. The cat developed gross lipemia that persisted at least 48 hours after the single dose of IVLT. Changes consistent with corneal lipidosis were observed and resolved within 1 week after IVLT.

NEW OR UNIQUE INFORMATION PROVIDED

This is the first report documenting the complications of persistent gross lipemia and suspected corneal lipidosis in a cat following IVLT. This report underscores the off-label, experimental nature of IVLT as a treatment for intoxication in cats.

Lipid emulsion mitigates local anesthesia-induced central nervous system toxicity in rats

The aim of the present study was to investigate the effect of intravenously administered lipid emulsion on local anesthetic (LA)-induced central nervous system (CNS) toxicity. A total of 100 male Sprague Dawley rats were allocated at random into the following groups: Sham (A), lidocaine (B), levobupivacaine (C) and ropivacaine (D). Groups B-D were each subdivided into three subgroups: Toxic, post-conditioning and pre-conditioning. Intracerebroventricular injections of 0.9% normal saline (sham group) or LA were administered via microsyringe; in addition, a 20% lipid emulsion was injected into tail vein prior to the LA injection (pre-conditioning subgroups) or following rat respiratory arrest (post-conditioning subgroups). The heart rate, blood pressure, neurological behavior scores, neuronal density and time from LA injection to respiratory arrest, apnea and start of arrhythmia were measured. Rats in the toxic groups died due to respiratory arrest following the injection of LA into the lateral ventricle. Rats in the post-conditioning subgroups were resuscitated from the LA-induced respiratory arrest, while the pre-conditioning subgroup rats exhibited no respiratory arrest. No significant differences in heart rate were observed between the toxic and post-conditioning subgroups in the levobupivacaine and ropivacaine groups (P>0.05); however, a significant difference was observed between these treatment groups and the rats treated with lidocaine (P<0.01). A significant difference was also observed in the time from the LA injection to the onset of arrhythmia among the rats in groups B, C and D (P<0.01). No significant differences in the neurological behavior scores and neuronal density were observed in the hippocampal CA1 zone among group C and D rats in the post- and pre-conditioning subgroups at various time-points following treatment. Beyond that, the same phenomena regarding neurological behavior scores was observed in post- and pre-conditioning subgroups of group B at 12 and 24 h treatment, contrasting with the statistically significant difference between post- and pre-conditioning subgroups at 6 h treatment (P<0.01). The results of the present study therefore indicate that pre- and post-conditioning with lipid emulsion effectively mitigates LA-induced CNS toxicity in rats.

Intralipid therapy for inadvertent peripheral nervous system blockade resulting from local anesthetic overdose

Although local anesthetics have an acceptable safety profile, significant morbidity and mortality have been associated with their use. Inadvertent intravascular injection of local anesthetics and/or the use of excessive doses have been the most frequent causes of local anesthetic systemic toxicity (LAST). Furthermore, excessive doses of local anesthetics injected locally into the tissues may lead to inadvertent peripheral nerve infiltration and blockade. Successful treatment of LAST with intralipid has been reported. We describe a case of local anesthetic overdose that resulted in LAST and in unintentional blockade of peripheral nerves of the lower extremity; both effects completely resolved with administration of intralipid.

Adherence to guidelines for the management of local anesthetic systemic toxicity is improved by an electronic decision support tool and designated "Reader"

BACKGROUND AND OBJECTIVES

A hardcopy or paper cognitive aid has been shown to improve performance during the management of simulated local anesthetic systemic toxicity (LAST) when given to the team leader. However, there remains room for improvement to ensure a system that can achieve perfect adherence to the published guidelines for LAST management. Recent research has shown that implementing a checklist via a designated reader may be of benefit. Accordingly, we sought to investigate the effect of an electronic decision support tool (DST) and designated "Reader" role on team performance during an in situ simulation of LAST.

METHODS

Participants were randomized to Reader + DST (n = 16, rDST) and Control (n = 15, memory alone). The rDST group received the assistance of a dedicated Reader on the response team who was equipped with an electronic DST. The primary outcome measure was adherence to guidelines.

RESULTS

For overall and critical percent correct scores, the rDST group scored higher than Control (99.3% vs 72.2%, P < 0.0001; 99.5% vs 70%, P < 0.0001, respectively). In the LAST scenario, 0 (0%) of 15 in the control group performed 100% of critical management steps, whereas 15 (93.8%) of 16 in the rDST group did so (P < 0.0001).

CONCLUSIONS

In a prospective, randomized single-blinded study, a designated Reader with an electronic DST improved adherence to guidelines in the management of an in situ simulation of LAST. Such tools are promising in the future of medicine, but further research is needed to ensure the best methods for implementing them in the clinical arena.

Evidence-based medicine for ultrasound-guided regional anesthesia

Available evidence favoring the use of ultrasound for regional anesthesia is reviewed, updated, and critically assessed. Important outcome advantages include decreased time to block onset; decreased risk of local anesthetic systemic toxicity; and, depending on the outcome definition, increased block success rates. Ultrasound guidance, peripheral nerve blocks, and central neuraxial blocks are discussed.

Potential avoidance of adverse analgesic effects using a biologically "smart" hydrogel capable of controlled bupivacaine release

Acute pain remains a tremendous clinical and economic burden, as its prevalence and common narcotic-based treatments are associated with poorer outcomes and higher costs. Multimodal analgesia portends great therapeutic promise, but rarely allows opioid sparing, and new alternatives are necessary. Microparticles (MPs) composed of biodegradable polymers [e.g., poly(lactic-co-glycolic acid) or PLGA] have been applied for controlled drug release and acute pain treatment research. However, foreign particles' presence within inflamed tissue may affect the drug release or targeting, and/or cause a secondary inflammatory reaction. We examined how small alterations in the particulate nature of MPs affect both their uptake into and subsequent activation of macrophages. MPs composed of PLGA and chitosan (PLGA-Chi) loaded with bupivacaine (BP) were engineered at different sizes and their opsonization by J774 macrophages was assessed. Uptake of PLGA-Chi by macrophages was found to be size dependent, but they were not cytotoxic or proinflammatory in effect. Moreover, encapsulation of MPs in a thermoresponsive loading gel (pluronic F-127) effectively prevented opsonization. Finally, MPs displayed sustained, tunable release of BP up to 7 days. These results demonstrate our ability to develop a drug delivery system capable of controlled release of local anesthetics to treat acute/subacute pain while concurrently avoiding enhanced inflammation.

Local anesthetic systemic toxicity

Local anesthetic systemic toxicity (LAST) is a rare yet devastating complication from the administration of local anesthesia. The ability to recognize and treat LAST is critical for clinicians who administer these drugs. The authors reviewed the literature on the mechanism, treatment, and prevention of LAST, with the goal of proposing a practical method for its management.

Measurement of the efficacy of 2% lipid in reversing bupivacaine- induced asystole in isolated rat hearts

Background

The reversal efficacy of 2% lipid emulsion in cardiac asystole induced by different concentrations of bupivacaine is poorly defined and needs to be determined.

Methods

Forty-two male Sprague–Dawley rats were randomly divided into seven groups: B40, B60, B80, B100, B120, B140 and B160, n = 6. The Langendorff isolated heart perfusion model was used, which consisted of a balanced perfusion with Krebs-Henseleit solution for 25 minutes and a continuous infusion of 100 μmol/L bupivacaine until asystole had been induced for 3 minutes. The hearts in the seven groups were perfused with Krebs-Henseleit solution containing a 2% lipid emulsion, and 40, 60, 80, 100, 120, 140 or 160 μmol/L bupivacaine, respectively. Cardiac recovery was defined as a spontaneous and regular rhythm with a rate-pressure product > 10% of the baseline value for more than 1 minute. Our primary outcome was the rate-pressure product 25 minutes after cardiac recovery. Other cardiac function parameters were also recorded.

Results

All groups demonstrated cardiac recovery. During the recovery phase, heart rate, rate-pressure product, the maximum left ventricular pressure rise and decline in heart rate in the B120-B160 groups was significantly lower than those in the B40-B80 groups (P < 0.05). The concentration of bupivacaine and the reversal effects of a 2% lipid emulsion showed a typical transoid S-shaped curve, R² = 0.9983, IC₅₀ value was 102.5 μmol/L (95% CI: 92.44 - 113.6).

Conclusions

There is a concentration-response relationship between the concentrations of bupivacaine and the reversal effects of 2% lipid emulsion.

Review of the use of lipid emulsion in nonlocal anesthetic poisoning

Intravenous lipid emulsion (ILE) has been used widely for the treatment of poisoning due to local anesthetic agent and is increasingly reported as a therapy for other forms of poisoning. This article will review the proposed mechanisms of action for ILE in poisoning and the evidence from animal studies and human experience supporting the use of ILE for poisoning due to nonlocal anesthetic agents.