Local Anesthetic Systemic Toxicity: A Narrative Literature Review and Clinical Update on Prevention, Diagnosis, and Management

A review of local anesthetic-induced heart toxicity using human induced pluripotent stem cell-derived cardiomyocytes

Local anesthetic (LA) cardiotoxicity is one of the main health problems in anesthesiology and pain management. This study reviewed the reported LA-induced cardiac toxicity types, risk factors, management, and mechanisms, with attention to the use of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in heart toxicity research. Important scientific databases were searched to find relevant articles. We briefly assessed the reported cardiotoxic effects of different types of LA drugs, including ester- and amide-linked LA agents. Furthermore, cardiotoxic effects and clinical manifestations, strategies for preventing and managing LA-induced cardiotoxic effects, pharmacokinetics, pharmacodynamics, and sodium channel dynamics regarding individual variability and genetic influences were discussed in this review. The applications and importance of hiPSC-CMs cellular model for evaluating the cardiotoxic effects of LA drugs were discussed in detail. This review also explored hiPSC-CMs' potential in risk assessment, drug screening, and developing targeted therapies. The main mechanisms underlying LA-induced cardiotoxicity included perturbation in sodium channels, ROS production, and disorders in the immune system response due to the presence of LA drugs. Furthermore, drug-specific characteristics including pharmacokinetics and pharmacodynamics are important determinants after LA drug injection. In addition, individual patient factors such as age, comorbidities, and genetic variability emphasize the need for a personalized approach to mitigate risks and enhance patient safety. The strategies outlined for the prevention and management of LA cardiotoxicity underscore the importance of careful dosing, continuous monitoring, and the immediate availability of resuscitation equipment. This comprehensive review can be used to guide future investigations into better understanding LA cardiac toxicities and improving patient safety.

Enhancing patient comfort in varicose vein treatment through combined lidocaine and ropivacaine tumescent anesthesia

Objective

To compare the analgesic effects of specific tumescent anesthetic solutions composed of lidocaine, ropivacaine, or a combination of lidocaine and ropivacaine during endovenous radiofrequency ablation for the treatment of great saphenous vein varicosities.

Method

This study included 149 patients with lower limb varicose veins who were admitted to our department between 2019 and 2023. The patients were randomly assigned to three groups: the lidocaine group (Group I), the ropivacaine group (Group II), and the lidocaine + ropivacaine group (Group III). Intraoperative vital signs, intraoperative and postoperative visual analog scale (VAS) pain scores, and long-term treatment outcomes were assessed using the venous clinical severity score (VCSS) based on clinical performance.

Results

There were no significant differences in age, body mass index, operative time, or blood loss among the three groups (P ≥ 0.05). The differences in the mean arterial pressure and heart rate during surgery in Group II were significantly greater than those in Groups I and III (P < 0.05). The intraoperative VAS scores in Group II were higher than those in Groups I and III (P < 0.05) and at 8 and 12 h postoperatively. There were no significant differences in VCSS among the groups (P ≥ 0.05).

Conclusion

The use of a tumescent anesthetic solution composed of lidocaine and ropivacaine significantly improved patient comfort during the perioperative period without affecting surgical outcomes. This formulation can be considered safe and reliable for preparing tumescent anesthesia solutions.

Lipid emulsion treatment for local anesthetic systemic toxicity in pediatric patients: A systematic review

BACKGROUND

Local anesthetic systemic toxicity (LAST) is rare, but fatal; the current widely used treatment is lipid emulsion (LE). The goal of this study was to analyze and review case reports on LE treatment for LAST in pediatric patients.

METHODS

We performed a systematic review using case reports on LE treatment for LAST in pediatric patients, searching PubMed and Scopus databases to March 2023 using the following keywords: ("local anesthetic toxicity" OR "local anesthetic systemic toxicity" OR LAST") AND ("newborn" OR "infant" OR "child" OR "children" OR "adolescent" OR "pediatric") AND ("lipid emulsion" OR "Intralipid").

RESULTS

Our search yielded 21 cases, revealing that nearly 43% patients with LAST were less than 1 year old, and most cases were caused by bupivacaine (approximately 67% cases). "Inadvertent intravascular injection" by anesthesiologists and "overdose of local anesthetics" mainly by surgeons were responsible for 52% and 24% cases of LAST, respectively. LAST occurred in the awake state (52%) and under general anesthesia (48%), mainly causing seizures and arrhythmia, respectively. Approximately 55% of patients received LE treatment in <10 minutes after LAST, mainly improving cardiovascular symptoms. A 20% LE (1.5 mL/kg) dose followed by 0.25 mL/kg/minutes dose was frequently used. LE and anticonvulsants were mainly used in the awake state, whereas LE with or without vasopressors was mainly used under general anesthesia. LE treatment led to full recovery from LAST in 20 cases; however, 1 patient died due to underlying disease.

CONCLUSION

Consequently, our findings reveal that LE is effective in treating pediatric LAST.

Top 25 Medications the Plastic and Reconstructive Surgery Trainee Should Know for an Emergency Medicine Department Consult

SUMMARY

Plastic surgery trainees are often called to render care in the emergency department (eg, for established patients, trauma, burns). Broad-based knowledge in pharmacotherapeutics during these encounters is critical. This includes an understanding of pain medications, anxiolytics, local anesthetics, antibiotics, anticoagulants, antidotes, and more to ensure optimal patient care. The purpose of this report is to describe 25 frequently used and other important medications that plastic surgery trainees should know for an adult emergency department encounter.

A randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of a bupivacaine hydrochloride implant in patients undergoing abdominoplasty

INTRODUCTION

Surgical site infiltration with bupivacaine hydrochloride (HCl) is a standard element of postoperative analgesia for soft tissue surgeries, but results in short-lived analgesia. A novel bupivacaine implant, XARACOLL (bupivacaine HCl), is Food and Drug Administration approved for treatment of acute postsurgical pain following adult inguinal herniorrhaphy. This study examined the efficacy and safety of the bupivacaine implant (300 mg) compared with placebo for postsurgical pain after abdominoplasty.

METHODS

In this double-blind, placebo-controlled study, patients undergoing abdominoplasty were randomized to three 100 mg bupivacaine implants or three placebo collagen implants, in a 1:1 ratio, implanted intraoperatively. No other analgesics were administered into the surgical site. Patients were allowed opioids and acetaminophen for postoperative pain. Patients were followed for up to 30 days after treatment.

PRIMARY OUTCOME

the analgesic effect of the bupivacaine implants through 24 hours postsurgery, measured by the sum of time-weighted pain intensity (SPI24). Prespecified key secondary outcomes included SPI48 and SPI72, percentage of opioid-free patients through 24, 48, and 72 hours, and adverse events, which were tested sequentially to control for multiplicity (ie, if the first variable failed to reach significance, no subsequent variables were declared statistically significant).

RESULTS

The bupivacaine implant patients (n=181) reported statistically significant lower SPI24 (mean (SD) SPI24=102 (43), 95% CI 95 to 109) compared with placebo patients (n=184; SPI24=117 (45), 95% CI 111 to 123, p=0.002). SPI48 was 190 (88, 95% CI 177 to 204) for INL-001 and 206 (96, 95% CI 192 to 219) for placebo, and not significantly different between groups. The subsequent secondary variables were therefore declared not statistically significant. SPI72 was 265 (131, 95% CI 244 to 285) for INL-001 and 281 (146, 95% CI 261 to 301) for placebo. The opioid-free percentage of patients at 24, 48, and 72 hours was 19%, 17%, and 17% for INL-001 and 6.5% for placebo patients (at all timepoints). The only adverse event occurring in ≥5% of patients and for which proportion INL-001 >placebo was back pain (7.7% vs 7.6%).

CONCLUSION

The study design was limited by not containing an active comparator. Compared with placebo, INL-001 provides postoperative analgesia that is temporally aligned with the period of maximal postsurgical pain in abdominoplasty and offers a favorable safety profile.

TRIAL REGISTRATION NUMBER

NCT04785625.

Effects of cognitive status on outcomes of groin hernia repair using various anesthesia techniques

BACKGROUND AND AIM

Because of increasing life expectancy, there is an increasing number of cognitively impaired older individuals undergoing surgeries such as groin hernia repair. Here, we evaluated the effects of cognitive status on postoperative complication rates in patients undergoing groin hernia repair using various anesthesia techniques. We also analyzed the rate of same-day hernia surgery in patients with cognitive decline.

METHODS

Patients who presented to our general surgery clinic for unilateral or bilateral inguinal or femoral hernia were prospectively classified into general (group 1), local (group 2), and spinal (group 3) anesthesia groups. The Mini-Mental State Examination (MMSE) was used for preoperative evaluation of each patient's cognitive status. The Visual Analog Scale (VAS) was used to evaluate postoperative pain. Groups were compared in terms of age, MMSE and VAS scores, cognitive decline and complication rates, and surgery duration.

RESULTS

In total, 33 (35.1%), 30 (31.9%), and 31 (33.0%) of 94 patients underwent surgery using general, local, and spinal anesthesia, respectively. The mean MMSE score did not differ among groups (p = 0.518). Cognitive decline was present in 18 (19.2%) patients, and the proportion did not significantly differ among groups. The complication rate did not differ between patients with and without cognitive decline. The mean surgery duration was similar among the three groups (p = 0.127). Group 2 had a lower mean postoperative VAS score, compared with the other groups (p < 0.001). Complications because of anesthesia and surgery were significantly more common in group 3 than in the other groups (p = 0.025). In the local anesthesia group, 7 patients had cognitive decline and 22 patients had normal cognition. There were no significant differences between patients with and without cognitive decline in terms of mean surgery duration (50.3 ± 15.4 min vs. 45.2 ± 10.7 min; p = 0.338) or mean VAS score (3.14 ± 0.90 vs. 3.13 ± 0.77; p = 0.985). Among the 22 and 7 patients without and with cognitive decline, 11 (50%) and 0 patients were discharged on the same day (p = 0.025). In the local anesthesia group, the respective median ages were 70, 52, and 59 years for patients with cognitive decline, patients with normal cognition discharged on the same day, and patients with normal cognition who were not discharged on the same day (p = 0.001).

CONCLUSION

Groin hernia repair was successfully performed under local anesthesia in all patients, including older patients with cognitive decline. Patients with cognitive decline were not discharged on the day of surgery, although the mean surgery duration and postoperative VAS score did not differ between patients with and without cognitive decline. Prolonged hospitalization in patients with cognitive decline may be related to their advanced age. Further studies are needed to determine the safety of same-day surgery in patients with cognitive decline.

Wide-Awake Local Anesthetic No Tourniquet Surgery of the Foot and Ankle

Wide awake local anesthetic no tourniquet (WALANT) surgery of the foot and ankle has the potential to offer safe and effective surgeon-based anesthesia for a significant number of surgeries about the foot and ankle. This has been documented with significant and growing body of literature. WALANT could offer significant advantages with respect to patient experience, per case cost of procedures as well as for improving access for patients to operative resources in a setting of scarcity or restricted access.

Population pharmacokinetic and safety analysis of ropivacaine used for erector spinae plane blocks

INTRODUCTION

Erector spinae plane blocks have become popular for thoracic surgery. Despite a theoretically favorable safety profile, intercostal spread occurs and systemic toxicity is possible. Pharmacokinetic data are needed to guide safe dosing.

METHODS

Fifteen patients undergoing thoracic surgery received continuous erector spinae plane blocks with ropivacaine 150 mg followed by subsequent boluses of 40 mg every 6 hours and infusion of 2 mg/hour. Arterial blood samples were obtained over 12 hours and analyzed using non-linear mixed effects modeling, which allowed for conducting simulations of clinically relevant dosing scenarios. The primary outcome was the Cmax of ropivacaine in erector spinae plane blocks.

RESULTS

The mean age was 66 years, mean weight was 77.5 kg, and mean ideal body weight was 60 kg. The mean Cmax was 2.5 ±1.1 mg/L, which occurred at a median time of 10 (7-47) min after initial injection. Five patients developed potentially toxic ropivacaine levels but did not experience neurological symptoms. Another patient reported transient neurological toxicity symptoms. Our data suggested that using a maximum ropivacaine dose of 2.5 mg/kg based on ideal body weight would have prevented all toxicity events. Simulation predicted that reducing the initial dose to 75 mg with the same subsequent intermittent bolus dosing would decrease the risk of toxic levels to <1%.

CONCLUSION

Local anesthetic systemic toxicity can occur with erector spinae plane blocks and administration of large, fixed doses of ropivacaine should be avoided, especially in patients with low ideal body weights. Weight-based ropivacaine dosing could reduce toxicity risk.

TRIAL REGISTRATION NUMBER

NCT04807504; clinicaltrials.gov.

Local anesthetics systemic toxicity in children: analysis of the French pharmacovigilance database

PURPOSE

To characterize clinical profile of pediatric local anesthetic (LA) systemic toxicity (LAST) and to identify determinants of life-threatening outcomes.

METHODS

Spontaneous reports notified to the French Pharmacovigilance Network were retrieved and followed by a case-by-case review, according to the following criteria: LA as suspected drug, age < 18 years, adverse drug reactions related to nervous system, cardiac, respiratory, psychiatric or general disorders. Multivariate logistic regression analysis was performed to identify factors leading to life-threatening reaction (i.e. continuous seizures or cardiorespiratory arrest).

RESULTS

Among 512 cases retrieved, 64 LAST cases were included (neonates 11%, infants 30%, children 36%, adolescents 23%) mainly involving lidocaine (47%), lidocaine + prilocaine (22%) and ropivacaine (14%). Toxicity profiles were neurological (58%), cardiac (11%) or mixed (20%) and 7 patients (11%) developed methemoglobinemia. LAST was life-threatening for 23 patients (36%) and 2 patients died. Doses were above recommendations in 26 patients (41%) and were not different between life-threatening and non-life-threatening cases. The context of use (general and orthopedic surgery, p = 0.006) and the type of LA agent (lidocaine, p = 0.016) were independently associated with a life-threatening outcome.

CONCLUSION

In this national retrospective analysis, LAST in children appear to be a rare event. Neurological and cardiac signs were the most frequently reported reactions. LAST in children can be life-threatening, even at therapeutic doses. Although a fatal outcome may anecdotally occur, the vast majority of patients recovered after appropriate medical care.

The Effect of Peripheral Nerve Block on Postoperative Delirium in Older Adults Undergoing Hip Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

This meta-analysis aimed to determine whether peripheral nerve blocks (PNB) reduce postoperative delirium (POD) in elderly patients undergoing hip surgery. This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42022328320). The PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched for randomized controlled trials (RCTs) on 26 April 2022. A total of 19 RCTs with 1977 participants were included. Perioperative PNB lowered the POD incidence on the third postoperative day (OR: 0.59, 95% CI [0.40 to 0.87], p = 0.007, I² = 35%), in patients without underlying cognitive impairment (OR: 0.47, 95% CI [0.30 to 0.74], p = 0.001, I² = 30%), and when a fascia iliaca compartment block (OR: 0.58, 95% CI [0.37 to 0.91], p = 0.02, I² = 0%) or a femoral nerve block (OR: 0.33, 95% CI [0.11 to 0.99], p = 0.05, I² = 66%) were performed. The pain score was also reduced (SMD: -0.83, 95% CI [-1.36 to -0.30], p = 0.002, I² = 95%) after PNB. Perioperative PNB can lower the POD incidence and pain scores up to the third postoperative day. However, considering the wide variety of PNBs performed, more trials are needed to identify the effects of each PNB on POD.

Lipid emulsion-induced recovery from unconsciousness caused by lidocaine toxicity: A case report

Lipid emulsion is used to treat systemic toxicity caused by local anesthetics. In addition, lipid emulsion was reported to be effective in ameliorating cardiovascular depression evoked by non-local anesthetic drug toxicity with high lipid solubility. A 47-year-old woman underwent local anesthetic infiltration with 40 mL of 2% lidocaine (20 and 20 mL) to remove a mass in the upper back. After operation, she experienced convulsions and loss of consciousness due to lidocaine toxicity. Midazolam followed by lipid emulsion was administered to treat central nervous system symptoms including unconsciousness and decreased Glasgow Coma Scale. The patient recovered from unconsciousness and presented improved Glasgow Coma Scale after lipid emulsion administration, and then fully recovered from local anesthetic systemic toxicity. This case suggests that early lipid emulsion treatment, before further progression of local anesthetic systemic toxicity, provides an enhanced recovery from unconsciousness and decreased Glasgow Coma Scale due to lidocaine toxicity.

Sodium bicarbonate reverts electrophysiologic cardiotoxicity of ropivacaine faster than lipid emulsions in a porcine model

Ropivacaine has been described as a safer local anaesthetic (LA); however, serious cardiotoxic accidents have been reported. Intravenous-lipid-emulsion (ILE) therapy during LA intoxication seems to act as an antidote. Sodium bicarbonate is the standard treatment for sodium channel blocker drug toxicity. We compared both antidotes on the reversion of electrophysiologic toxicity induced by ropivacaine. Ropivacaine 5 mg kg^-1 was administered in 24 pigs, and 3 min later, the animals received ILE: 1.5 ml kg^-1  + 0.25 ml kg^-1  min^-1 (ILE group); sodium bicarbonate: 2 mEq kg^-1  + 1 mEq kg^-1  h^-1 (NaHCO₃ group); saline solution (CTL group). Electrophysiological parameters were evaluated for 30 min. The area under the curve (AUC) for the first 5 or 30 min was compared between groups. Ropivacaine induced a lengthening of the PR interval by 17% (P = 0.0001), His-ventricle-interval by 58% (P = 0.001), sinus QRS complex by 56% (P = 0.0001), paced QRS at 150 bpm by 257% (P = 0.0001), and at 120 bpm by 143% (P = 0.0001) in all groups. At 5 min after treatment, sinus QRS in the NaHCO₃ group was shorter than that in the CTL group (AUC_QRS5 , P = 0.003) or ILE group (AUC_QRS5 , P = 0.045). During the first minute, seven of the animals in the NaHCO₃ group vs. two in the ILE or 0 in the CTL group recovered more than 30% of the sinus QRS previously lengthened by ropivacaine (P = 0.003). Sodium bicarbonate reversed the electrophysiological toxicity of ropivacaine faster than ILE and control groups.

Pain Reduction Using Ropivacaine in Tumescent Solution following Lipoaspiration

Tumescent solution utilizing dilute epinephrine and a local anesthetic agent injected into a fat compartment has been shown to effectively minimize blood loss and postoperative pain in liposuction. Ropivacaine has a longer duration of action compared to lidocaine and is a potential analgesic in tumescent solution. We sought to explore the effect of using ropivacaine in a tumescent technique with a focus on its efficacy for pain control postoperatively. The formula for the tumescent technique used combined 1 mL of epinephrine with 30 mL of ropivacaine into 500 mL of injectable saline. Tumescent solution was injected manually into fat donor sites of 10 consecutive patients followed by a 20-minute waiting period before beginning fat aspiration with liposuction cannula. Patients were seen immediately following their surgery and on postoperative day 1 and reported their pain using a numerical scale. Data gathered included the amount of ropivacaine used, average pain rating, and the average amount of fat removed. On average, participants reported little to no pain at the donor sites immediately following surgery and on postoperative day 1. Based on the low need for pain medication, we believe that ropivacaine may be successfully used in tumescent solution to reduce postoperative pain.

Regional Anesthesia in the Emergency Department: an Overview of Common Nerve Block Techniques and Recent Literature

Purpose of Review

This review seeks to discuss the use of RA in the ED including benefits of administration, types of RA by anatomic location, complications and management, teaching methods currently in practice, and future applications of RA in the ED.

Recent Findings

The early use of RA in pain management may reduce the transition of acute to chronic pain. Multiple plane blocks have emerged as feasible and efficacious for ED pain complaints and are now being safely utilized.

Summary

Adverse effects of opioids and their potential for abuse have necessitated the exploration of substitute therapies. Regional anesthesia (RA) is a safe and effective alternative to opioid treatment for pain in the emergency department (ED). RA can manage pain for a wide variety of injuries while avoiding the risks of opioid use and decreasing length of stay when compared to other forms of analgesia and anesthesia, without compromising patient satisfaction.

Sudden quadriparesis after non-overdose local anesthesia

Background

A well-known anesthetic, lidocaine is the most widely used local anesthetic. Local anesthetic systemic toxicity (LAST) is a life-threatening event with common and prominent presentations of central nervous system (CNS) toxicity and cardiovascular toxicity. The most frequent and prominent early warning signs and symptoms of LAST are central nervous system symptoms. While rare, cases quadriparesis after the administration of lidocaine has been reported.

Case presentation

In this paper, we report a very rare case of quadriparesis after local anesthesia administration for vocal cord cyst-removal surgery, which dramatically improved after treatment. LAST can occur during various routes of lidocaine administration, such as local spray. A possible mechanism of our case could be the local diffusion of lidocaine to the spinal cord, which caused the symptoms to mimic anterior cord syndrome.

Conclusions

Our case presented a favorable outcome following the administration of intravenous lipid emulsion (ILE) for non-over dose local anesthetic drug induced spinal cord inhibition symptoms. These findings highlight the need for further research on the use of ILE to reverse LAST and other adverse effects of local anesthetics.

Local anesthetics for the Nephrologist

Several specialists in medicine use local anesthetics. In patients with kidney disease, these agents are used during catheter insertions for hemodialysis and peritoneal dialysis, arteriovenous fistula and graft procedures, kidney transplantation, parathyroidectomy, kidney biopsies, and dental and skin procedures. Patients on chronic hemodialysis use a topical application prior to use of needles for arteriovenous fistula cannulation before starting dialysis. They are also used to manage acute and chronic pain conditions, in regional nerve blockade and in multi-modal enhanced recovery protocols. Despite their frequent use by both physicians and patients, data on the use of local anesthetics in patients with kidney impairment are not well reported. This review will summarize the use of local anesthetics in chronic kidney disease, describe their pharmacology and the impact of lower estimated glomerular filtration rate on their pharmacokinetics, and suggest dose regulation in those with kidney dysfunction.

Regional anesthesia for orthopedic procedures: What orthopedic surgeons need to know

Regional anesthesia is an integral component of successful orthopedic surgery. Neuraxial anesthesia is commonly used for surgical anesthesia while peripheral nerve blocks are often used for postoperative analgesia. Patient evaluation for regional anesthesia should include neurological, pulmonary, cardiovascular, and hematological assessments. Neuraxial blocks include spinal, epidural, and combined spinal epidural. Upper extremity peripheral nerve blocks include interscalene, supraclavicular, infraclavicular, and axillary. Lower extremity peripheral nerve blocks include femoral nerve block, saphenous nerve block, sciatic nerve block, iPACK block, ankle block and lumbar plexus block. The choice of regional anesthesia is a unanimous decision made by the surgeon, the anesthesiologist, and the patient based on a risk-benefit assessment. The choice of the regional block depends on patient cooperation, patient positing, operative structures, operative manipulation, tourniquet use and the impact of post-operative motor blockade on initiation of physical therapy. Regional anesthesia is safe but has an inherent risk of failure and a relatively low incidence of complications such as local anesthetic systemic toxicity (LAST), nerve injury, falls, hematoma, infection and allergic reactions. Ultrasound should be used for regional anesthesia procedures to improve the efficacy and minimize complications. LAST treatment guidelines and rescue medications (intralipid) should be readily available during the regional anesthesia administration.

Complications After Dental Sedation: A Myotonic Mystery Case Report

Myotonic dystrophy (dystrophia myotonica; DM) is an uncommon progressive hereditary muscle disorder that can present with variable severity at birth, in early childhood, or most commonly as an adult. Patients with DM, especially type 1 (DM1), are extremely sensitive to the respiratory depressant effects of sedative-hypnotics, anxiolytics, and opioid agonists. This case report describes a 37-year-old male patient with previously undiagnosed DM1 who received dental care under minimal sedation using intravenous midazolam. During the case, the patient experienced 2 brief episodes of hypoxemia, the second of which required emergency intubation after propofol and succinylcholine and resulted in extended hospital admission. A lipid emulsion (Liposyn II 20%) infusion was given approximately 2 hours after the last local anesthetic injection due to slight ST elevation and suspicion of local anesthetic toxicity (LAST). Months after treatment, the patient suffered a fall resulting in a fatal traumatic brain injury. Complications noted in this case report were primarily attributed to the unknown diagnosis of DM1, although additional precipitating factors were likely present. This report also provides a basic review of the literature and clinical guidelines for managing myotonic dystrophy patients for dental care with local anesthesia, sedation, or general anesthesia.

Radiofrequency ablation and related ultrasound-guided ablation technologies for treatment of benign and malignant thyroid disease: An international multidisciplinary consensus statement of the American Head and Neck Society Endocrine Surgery Section with the Asia Pacific Society of Thyroid Surgery, Associazione Medici Endocrinologi, British Association of Endocrine and Thyroid Surgeons, European Thyroid Association, Italian Society of Endocrine Surgery Units, Korean Society of Thyroid Radiology, Latin American Thyroid Society, and Thyroid Nodules Therapies Association

BACKGROUND

The use of ultrasound-guided ablation procedures to treat both benign and malignant thyroid conditions is gaining increasing interest. This document has been developed as an international interdisciplinary evidence-based statement with a primary focus on radiofrequency ablation and is intended to serve as a manual for best practice application of ablation technologies.

METHODS

A comprehensive literature review was conducted to guide statement development and generation of best practice recommendations. Modified Delphi method was applied to assess whether statements met consensus among the entire author panel.

RESULTS

A review of the current state of ultrasound-guided ablation procedures for the treatment of benign and malignant thyroid conditions is presented. Eighteen best practice recommendations in topic areas of preprocedural evaluation, technique, postprocedural management, efficacy, potential complications, and implementation are provided.

CONCLUSIONS

As ultrasound-guided ablation procedures are increasingly utilized in benign and malignant thyroid disease, evidence-based and thoughtful application of best practices is warranted.

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.

Asystolic Cardiac Arrest Associated With Unstable Bradycardia During Augmentation Mammaplasty: A Case Report

Cardiac arrest is a rare but reported complication during breast augmentation surgery. It is even more rare in a reportedly healthy patient without preexisting cardiac disease. The authors present the case of a healthy 34-year-old female who underwent elective bilateral augmentation mammaplasty and experienced unanticipated asystolic cardiac arrest intraoperatively following general anesthesia supplemented by a regional pectoral (pec I) nerve block. The performing plastic surgeon provided cardiopulmonary resuscitation while the anesthesiologist initiated a rescue protocol per Advanced Cardiac Life Support (ACLS) guidelines. Fortunately, the patient was resuscitated in a timely manner and had a successful return of spontaneous circulation within 1 minute. This case report serves to briefly review the literature and recommendations on proper resuscitation of cardiac arrest per ACLS protocols as well as discuss unstable bradycardia in otherwise healthy patients undergoing breast augmentation surgery. Plastic surgeons and anesthesiologists who perform this procedure should be aware of the possible, rare but serious progression to asystole as well as the proper resuscitative measures to take should they be required.

LEVEL OF EVIDENCE 5

Lido-OH, a Hydroxyl Derivative of Lidocaine, Produced a Similar Local Anesthesia Profile as Lidocaine With Reduced Systemic Toxicities

Background: lidocaine is one of the most commonly used local anesthetics for the treatment of pain and arrhythmia. However, it could cause systemic toxicities when plasma concentration is raised. To reduce lidocaine’s toxicity, we designed a hydroxyl derivative of lidocaine (lido-OH), and its local anesthesia effects and systemic toxicity in vivo were quantitively investigated.

Method: the effectiveness for lido-OH was studied using mouse tail nerve block, rat dorsal subcutaneous infiltration, and rat sciatic nerve block models. The systemic toxicities for lido-OH were evaluated with altered state of consciousness (ASC), arrhythmia, and death in mice. Lidocaine and saline were used as positive and negative control, respectively. The dose-effect relationships were analyzed.

Results: the half effective-concentration for lido-OH were 2.1 mg/ml with 95% confident interval (CI95) 1.6–3.1 (lidocaine: 3.1 mg/ml with CI95 2.6–4.3) in tail nerve block, 8.2 mg/ml with CI95 8.0–9.4 (lidocaine: 6.9 mg/ml, CI95 6.8–7.1) in sciatic nerve block, and 5.9 mg/ml with CI95 5.8–6.0 (lidocaine: 3.1 mg/ml, CI95 2.4–4.0) in dorsal subcutaneous anesthesia, respectively. The magnitude and duration of lido-OH were similar with lidocaine. The half effective doses (ED₅₀) of lido-OH for ACS was 45.4 mg/kg with CI95 41.6–48.3 (lidocaine: 3.1 mg/kg, CI95 1.9–2.9), for arrhythmia was 16.0 mg/kg with CI95 15.4–16.8 (lidocaine: 3.0 mg/kg, CI95 2.7–3.3), and for death was 99.4 mg/kg with CI95 75.7–124.1 (lidocaine: 23.1 mg/kg, CI95 22.8–23.4). The therapeutic index for lido-OH and lidocaine were 35.5 and 5.6, respectively.

Conclusion: compared with lidocaine, lido-OH produced local anesthesia at similar potency and efficacy, but with significantly reduced systemic toxicities.

Multiple myeloma and malignant lesions: a potential risk factor for local anesthetic systemic toxicity

BACKGROUND

Multiple myeloma is a cancer of plasma cells that often leads to complications including osteolytic bone lesions, nephropathy and neuropathy. Multiple myeloma is only one etiology of many cancer pain conditions that may necessitate interventional pain treatment when refractory to multimodal medications. Notably, local anesthetic systemic toxicity is a rare but life-threatening complication of local anesthetic administered for these interventions.

CASE PRESENTATION

A 50-60-year-old woman presented with multiple myeloma complicated by chronic bone pain and in an acute pain crisis. A fluoroscopic-guided L4-5 epidural catheter was placed with clinical doses of bupivacaine for comfort to undergo MRI of the spine. Soon after, she became tachycardic, tachypneic and hypoxic requiring non-invasive positive pressure airway support. As this respiratory distress was attributed to a large pleural effusion, a pigtail catheter was inserted in the intensive care unit with submaximally dosed lidocaine infiltration. She then developed a left bundle branch block followed by cardiovascular collapse minimally responsive to high-dose inotrope and vasopressor support. Lipid emulsion was started with dramatic therapeutic response and recovery to baseline. A CT of the thoracolumbar spine showed worsening extensive lytic lesions throughout all vertebral bodies and ribs from diffuse myeloma.

CONCLUSIONS

Patients with oncologic lesions focal to the thoracolumbar spine may be at higher risk for local anesthetic systemic toxicity from palliative epidurals due to increased cancer-related angiogenesis. Likewise, local anesthetic infiltration for procedures near any malignant sites could have a similar risk and may require lower initial fractionated dosages with increased vigilance.

Activation of NLR family, domain of pyrin containing 3 inflammasome by nitrous oxide through thioredoxin-interacting protein to induce nerve cell injury

Nitrous Oxide (N₂O) has been shown to be neurotoxic, but its specific mechanism is still unclear. The purpose of this work is to probe into the impact of N₂O on nerve cell injury through regulating thioredoxin-interacting protein (TXNIP)/the NOD-like receptor domain of pyrin containing 3 (NLRP3) pathway. The results indicated that, N₂O exposure elevated TXNIP/NLRP3 expression in vivo and in vitro, led to declined learning and memory capabilities in mice, reduced apoptosis rate in hippocampal neuron and Nissl bodies, elevated inflammatory factors TNF-α, IL-1β and IL-6 levels, as well as cleaved caspase-3 and Bax expressions, and reduced Bcl-2 expression. Overexpressing TXNIP or NLRP3 further aggravated these injuries, but knocking down TXNIP or NLRP3 improved them. CO-IP indicated that TXNIP and NLRP3 can be combined, with interaction relationship. All in all, the results manifested that N₂O is available to promote nerve cell inflammation and apoptosis through activating the TXNIP/NLRP3 pathway that can be used as a potential target for N₂O-induced nerve damage in the future.

A description of the clinical course of severe benzonatate poisonings reported in the literature and to NPDS: A systematic review supplemented with NPDS cases

BACKGROUND

Benzonatate is a commonly prescribed medication that can be lethal in acute overdose of a small number of capsules.

OBJECTIVE

This was a systematic review to describe the course of severe poisoning and deaths from benzonatate supplemented with the National Poison Data System (NPDS) fatalities module.

METHODS

The NPDS was queried from 2000 to 2018 for benzonatate fatalities. Pubmed, Cochrane, Embase, and Google Scholar were searched for combinations of benzonatate and "poisoning," "overdose," and "toxicity." References of relevant articles were searched for additional publications. Articles were included if they described the clinical course of at least one patient suffering from benzonatate poisoning and available in English. Dual independent review and extraction were performed.

RESULTS

Seventeen cases from NPDS and 19 published reports met the inclusion criteria resulting in 36 cases, mostly (28/36) self-harm ingestions. Most patients were young [17 (11-29), median (IQR)] and female (22). Onset of toxicity was rapid at <5 min (9). Most common symptoms included cardiac arrest (29), seizures (24), and dysrhythmias (24). Treatments included intubation (26), cardiopulmonary resuscitation (28), vasopressors (20) and others. Return of spontaneous circulation was achieved in 23/28 patients, but most had significant neurologic deficits or other end organ damage and 5 survived with a good neurologic outcome.

CONCLUSION AND RELEVANCE

Overdose ingestions of benzonatate can cause significant toxicity with a rapid onset. Interventions performed were generally supportive in nature. Duration of directly toxic effects is short, but dramatic with neurologic devastation and resuscitated patients often still have a poor outcome.

Hair Transplant Practice Guidelines

The field of hair transplant (HT) has grown exponentially in the past decade, especially after the introduction of follicular unit excision (FUE). There is much variation in criteria for case selection, the technique, pre- and post-procedure protocols, by different surgeons. Techniques continue to evolve and evidence in the form of controlled data is not available for all techniques and protocols being used; there is also a debate as to who can do what, what should be the training for staff, role of technicians. This has led to a situation wherein medico legal issues have cropped up as to what is minimum acceptable. An attempt is made to summarize standard protocols with the available evidence. It is emphasized that the objective of these guidelines is to recommend minimum standards for practice of hair transplantation. The principles outlined in these guidelines are of a general nature only, minimal in their level and are not meant to cover all situations. It should be understood that these recommendations are by no means binding and universal, represent minimum standards only and as in all surgical techniques, variations in techniques are possible. It is also further clarified that these are based on current literature, and as science evolves, these guidelines could also change in future. Where published evidence is not available, consensus expert opinion is presented. The task force emphasizes that each patient has to be treated on his/her own merit and that these guidelines do not limit the physician from making an appropriate choice or the necessary innovation for a given patient. The task force recognizes that the treating surgeon is best suited to decide what is needed for a given patient in a given situation. Innovations in medicine need flexibility in approach and these guidelines do not limit the surgeon from undertaking innovative research.

The 14-day repeated-dose toxicity studies of a fixed-dose combination, QXOH/levobupivacaine, via subcutaneous injection in mice

QXOH-LB, a fixed-dose combination (35 mM QXOH and 10 mM levobupivacaine) has been shown to induce a long duration of local anesthesia in animal efficacy testing, which indicates potential for postoperative pain management. In this study, we evaluated the potential toxicity of QXOH-LB in NIH mice under the Guidance on the repeated-dose toxicity published by the China Food and Drug Administration. Mice (n = 30 per sex per group) were subcutaneously injected 5, 10, 20 mg/kg QXOH-LB, 5, 10, 20 mg/kg QXOH, and 5 mg/kg levobupivacaine (LB) once a day for 14 days with sacrifice of main study animals; remaining mice (n = 10 per sex per group) were monitored for an additional 4-week recovery period. Mice in the 10 and 20 mg/kg QXOH, and 20 mg/kg QXOH-LB died, which was considered due to excessive respiratory inhibition. The doses of 10 mg/kg QXOH-LB and 5 mg/kg QXOH were well tolerated without any clinical signs of toxicity. Therefore, the no-observed-adverse-effect level (NOAEL) of QXOH-LB and QXOH was considered to be 10 and 5 mg/kg/day, respectively. In the dose range from 5 to 20 mg/kg, the exposure of QXOH and LB in QXOH-LB was equal to each agent used alone at the same dose in NIH mice. There was no gender difference on exposure and no evidence of accumulation.

Pediatric Cardiac Arrest Resuscitation

Pediatric cardiac arrest is a relatively rare but devastating presentation in infants and children. In contrast to adult patients, in whom a primary cardiac dysrhythmia is the most likely cause of cardiac arrest, pediatric patients experience cardiovascular collapse most frequently after an initial respiratory arrest. Aggressive treatment in the precardiac arrest state should be initiated to prevent deterioration and should focus on support of oxygenation, ventilation, and hemodynamics, regardless of the presumed cause. Unfortunately, outcomes for pediatric cardiac arrest, whether in hospital or out of hospital, continue to be poor.

Reversed phase liquid chromatography for the enantioseparation of local anaesthetics in polysaccharide-based stationary phases. Application to biodegradability studies

A comprehensive study on the chiral separation of bupivacaine, mepivacaine, prilocaine and propanocaine with eight commercial polysaccharide-based chiral stationary phases (CSPs) in reversed phase conditions compatible with MS detection is performed. Methanol and acetonitrile are used as organic modifiers. Retention and resolution values obtained for each compound in the different CSPs and mobile phases are compared. The polysaccharide-based CSPs tested present different enantioselectivity towards the analytes. From the results, the experimental conditions for determining the enantiomers of bupivacaine, mepivacaine, prilocaine and propanocaine in saline aqueous samples using MS detection are used, for the first time, to perform an enantioselective biodegradability study.

Exposures to Dental Products, Stomatological Preparations, and in Dental Care and Toothache reported to the PIC Erfurt (1997 to 2017)

We examined human exposures to dental products (EDP), stomatological preparations (ESP), and in the context of dental care (EDC) or toothache (ETA) registered by the Poisons Information Centre (PIC) Erfurt from 1997 to 2017. Dental products like dental technical and filling materials belong to medical devices. Stomatological preparations were classified according to the ATC code and symptom severity to the Poisoning Severity Score (PSS). In total, 156 cases of EDP (136 cases with different tooth filling materials), 1167 cases of ESP (55.6% fluoride containing products), 979 cases of EDC, and 331 cases of ETA were registered. Symptom severity in EDP and ESP were asymptomatic or mild. In ETA and EDC, however, 35 cases with moderate and 5 cases with severe symptoms were detected. 5 moderate and 3 severe cases were caused by prolonged paracetamol overdose. Severe bleeding occurred following tooth extraction in a 41 year-old phenprocoumon treated patient after self-medication with acetylsalicylic acid and metamizole. Gingival injection of lidocaine plus epinephrine in a 37 year-old healthy woman resulted in severe bradycardia and cardiac arrest. Acute toxicity of EDP and ESP appears to be low. Prolonged paracetamol overdose because of toothache, and some dental treatment can result in severe symptoms.

Local Anesthetic Toxicity in the Geriatric Population

This article provides a concise overview of local anesthetic systemic toxicity, its history, mechanisms, risk factors, prevention, clinical presentation, and treatment, with a special emphasis on issues specific to the geriatric population. The authors used MEDLINE, Scopus, and Google Scholar to search for original research articles (human and animal studies), registries data, case reports, review articles, and pertinent online publications using the combinations of the following search terms: local anesthetics, local anesthetic systemic toxicity, intralipid, lipid emulsion, Exparel, ultrasound-guidance, regional anesthesia, lidocaine, bupivacaine, ropivacaine, cocaine, procaine, tetracaine, levobupivacaine, liposomal bupivacaine, lignocaine. Local anesthetic systemic toxicity continues to occur despite the use of putatively less cardiotoxic formulations of local anesthetics and more common use of ultrasound guidance. The elderly appear to be at a disproportionately increased risk for toxicity owing to the presence of relevant comorbidities and decreased muscle mass. Examination of recent case reports involving patients over the age of 65 years demonstrates that inadvertent overdosing is responsible for some cases of local anesthetic systemic toxicity. Elderly patients are at increased risk of local anesthetic systemic toxicity. When considering use of local anesthetics in older patients, special attention should be paid to the presence of systemic disease and muscle wasting. The safety of regional anesthesia and multi-modal analgesia among these at-risk patients will be improved by educating physicians and staff to recognize and manage local anesthetic systemic toxicity.