Local anesthetic systemic toxicity: A narrative review for emergency clinicians

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.

Emergency Medicine Case Study on Local Anesthetic Systemic Toxicity

The purpose of this case study on local anesthetic systemic toxicity (LAST), a potentially life-threatening complication of local anesthetic, is to ensure that emergency nurse practitioners (ENPs) are knowledgeable on this disease process. Local anesthetics are used frequently, often daily, by ENPs, as well as multiple other health care providers for various procedures. They should be knowledgeable of the steps to resuscitate a patient who may have severe LAST. This case study reviews the emergency management of LAST, including pharmacologic treatment, deviations from routine advanced resuscitative guidelines, and disposition of the patient upon successful resuscitation. Additionally, risk assessment and clinical manifestations will be discussed. After reviewing this case study, ENPs should be able to recognize the presentation of LAST and provide emergent management to reduce complications, comorbidities, and death.

Acute Pain Management in a Multi-site Trauma Patient

Pain management is often difficult in the setting of multi-site trauma such as that caused by motor vehicle accidents (MVA), which is especially compounded in the setting of polysubstance abuse. This often results in patients with poor pain tolerance requiring escalating doses of opioid therapy, which creates a vicious cycle. The use of peripheral nerve blocks (PNB) has been shown to decrease overall opioid consumption and can be used effectively to manage postoperative pain in this patient population. Our case report aims to highlight the importance of PNBs as part of a multimodal approach to pain management in patients with polytrauma in the setting of polysubstance abuse.

The minimum effective concentration (MEC90) of bupivacaine for an ultrasound-guided suprainguinal fascia iliaca compartment block for analgesia in knee surgery: a dose-finding study

BACKGROUND

In recent years, the suprainguinal fascia iliaca compartment block (SFICB) has become more common in clinical practice. This assessor-blinded dose-finding study aimed to determine the minimum effective concentration (MEC90, MEC95) of bupivacaine for a single-injection SFICB in patients undergoing arthroscopic anterior cruciate ligament repair.

METHODS

This prospective study was conducted at a tertiary hospital (postoperative recovery room and ward). The SFICB was performed as a postsurgical intervention after spinal anesthesia. Seventy patients were allocated using the biased-coin design up-and-down sequential method. The ultrasound-guided SFICB was performed using different bupivacaine concentrations, and standard multimodal analgesia was administered to all patients. Block success was defined as the absence of pain or presence of only tactile sensation during the pinprick test conducted on the anterior and lateral regions of the mid-thigh six hours postoperatively.

RESULTS

According to isotonic regression and bootstrap CIs, the MEC90 value of bupivacaine for a successful SFICB was 0.123% (95% CI [0.098, 0.191]) and the MEC95 value was 0.188% (95% CI [0.113, 0.223]).

CONCLUSIONS

Our study showed that the MEC90 and MEC95 values for bupivacaine administered via an SFICB for analgesia were 0.123% and 0.188%, respectively. One advantage of using lower concentrations of bupivacaine is the associated reduction in quadriceps weakness.

Local Anesthetic Systemic Toxicity Joint Management in the Prehospital Environment: A Case Report

Local anesthetic systemic toxicity (LAST) is a potentially life-threatening complication that may occur after local anesthetic injection. After reaching the systemic circulation, cardiovascular and central nervous system derangements may appear, with potentially fatal complications if left untreated. The pillars for LAST treatment are advanced life support measures, airway and seizure management, and a 20% lipid emulsion intravenous administration. When occurring in the prehospital setting, LAST is difficult to recognize, mostly because of its features overlapping with other acute conditions. Prompt treatment is also challenging because lipid emulsion may not be routinely carried on emergency vehicles. This article reports a case of LAST occurring in a dental ambulatory located in a remote location within the Italian Alps in which effective communication among different components of the same regional health care system (dispatch center, prehospital teams, and hospital network) led to fast lipid emulsion retrieval en route and on-site toxicity resolution. This case can inspire future operational changes, such as antidote networks available to prehospital emergency medicine crews, avoiding unnecessary deployment of antidotes on ambulances or helicopters, which is difficult to preserve without increasing management costs. However, to be established, such a network would need protocols to facilitate antidote retrieval, training focused on toxidromes recognition, and improved communication skills among different professionals involved in prehospital emergency medicine.

Local Anesthetic Systemic Toxicity (LAST): More Common Than You Think

The number of anesthetic body procedures in the United States is rapidly increasing, with many being performed on an outpatient basis. These procedures are advertised as being safe, and many times the serious complications may not be discussed. Although local anesthetic systemic toxicity is a rare complication, it is associated with an increase in morbidity. The emergency department staff should be aware of the possibility of this rare complication, as well as the variety of resulting symptoms (from minor to severe), potential sequelae, and appropriate management for patients who have undergone an outpatient anesthetic body procedure. Multiple factors contribute to the development of local anesthetic systemic toxicity, resulting in life-threatening effects on the neurologic and cardiovascular systems. Also, the site of administration, along with the local anesthetic agent used, can impact the risk of the development of local anesthetic systemic toxicity. To minimize the risk and ensure the best possible outcome for these patients, emergency department staff must be highly aware of the mechanisms, risk factors, prevention, and management/treatment of local anesthetic systemic toxicity.

Advancing pain management for extremity trauma: the evolution of ultrasound-guided nerve blocks for patients in the supine position in trauma centers

PURPOSE

Trauma, particularly extremity trauma, poses a considerable challenge in healthcare, especially among young adults. Given the severity of patient pain and the risks associated with excessive opioid use, managing acute pain in trauma centers is inherently complex. This study aims to investigate the application and benefits of ultrasound-guided nerve blocks for early pain management in patients with extremity trauma positioned supine.

METHODS

A comprehensive literature review was conducted to assess the effectiveness and advantages of ultrasound-guided peripheral nerve blocks in the acute pain management of extremity trauma patients in the supine position. Special emphasis was placed on evaluating the selection criteria, indications, contraindications, adverse reactions, and potential complications associated with these nerve block techniques.

RESULTS

Ultrasound-guided nerve blocks represent a safer and more precise option for managing pain in extremity trauma patients placed in the supine position. These techniques offer significant advantages in terms of reducing healthcare expenses, diminishing reliance on opioid medications, and mitigating opioid-related complications. Nonetheless, challenges may arise due to the necessity for patient cooperation during specific nerve block procedures.

CONCLUSION

Ultrasound-guided nerve blocks present a promising avenue for early pain management in extremity trauma patients positioned supinely. Their implementation can lead to improved patient outcomes by alleviating pain severity, reducing opioid consumption, and cutting down healthcare costs. Further research and clinical integration of these techniques is imperative to enhance pain management protocols in trauma centers.

Ultrasound-guided nerve blocks in emergency medicine practice: 2022 updates

OBJECTIVES

In the Emergency Department (ED), ultrasound-guided nerve blocks (UGNBs) have become a cornerstone of multimodal pain regimens. We investigated current national practices of UGNBs across academic medical center EDs, and how these trends have changed over time.

METHODS

We conducted a cross-sectional electronic survey of academic EDs with ultrasound fellowships across the United States. Twenty-item questionnaires exploring UGNB practice patterns, training, and complications were distributed between November 2021-June 2022. Data was manually curated, and descriptive statistics were performed. The survey results were then compared to results from Amini et al. 2016 UGNB survey to identify trends.

RESULTS

The response rate was 80.5% (87 of 108 programs). One hundred percent of responding programs perform UGNB at their institutions, with 29% (95% confidence interval (CI), 20%-39%) performing at least 5 blocks monthly. Forearm UGNB are most commonly performed (96% of programs (95% CI, 93%-100%)). Pain control for fractures is the most common indication (84%; 95% CI, 76%-91%). Eighty-five percent (95% CI, 77%-92%) of programs report at least 80% of UGNB performed are effective. Eighty-five percent (95% CI, 66%-85%) of programs have had no reported complications from UGNB performed by emergency providers at their institution. The remaining 15% (95% CI, 8%-23%) report an average of 1 complication annually.

CONCLUSIONS

All programs participating in our study report performing UGNB in their ED, which is a 16% increase over the last 5 years. UGNB's are currently performed safely and effectively in the ED, however practice improvements can still be made. Creating multi-disciplinary committees at local and national levels can standardize guidelines and practice policies to optimize patient safety and outcomes.

Adulterants present in the San Diego county fentanyl supply: a laboratory analysis of seized law enforcement samples

BACKGROUND

The opioid overdose crisis is one of the worst public health crises ever to face the US and emerging evidence suggests its effects are compounded by the presence of drug adulterants. Here we report our efforts to characterize the adulterants present within the local fentanyl supply of San Diego County, obtained from undifferentiated drug samples seized by local law enforcement over the calendar year 2021.

METHODS

Thirty-two participating local law enforcement agencies across San Diego submitted 4838 unknown individual illicit drug samples (total of 312 kg) to the San Diego County Sheriff's Department Regional Crime Laboratory for identification.

RESULTS

Qualitative analysis of these samples via FTIR and GC-MS identified methamphetamine (38.7%), fentanyl (20.8%), diacetylmorphine (heroin) (10.2%), codeine (5.8%) and alprazolam (4.3%) as the most common illicit substances and the presence of 52 unique adulterants. The most common adulterants included 4-methylaminoantipyrine (4-MAAP) (10.9%), mannitol (9%), acetaminophen (8.5%), methamphetamine (4.2%), diacetylmorphine (heroin) (3.6%), tramadol (1.9%), and xylazine (1.7%). Several additional pharmacologically active adulterants and contaminants of interest were also identified.

CONCLUSION

This analysis is vital for public health use and harm reduction efforts at the level of the individual consumer. Continued direct surveillance of the drug supply is necessary for the detection of potentially harmful adulterants that may pose serious threats to the public.

Analgesic Techniques for Managing Orthopedic Injuries: A Review for the Emergency Clinician

BACKGROUND

Orthopedic injuries are commonly managed in the emergency department (ED) setting. Fractures and dislocations may require reduction for proper management. There are a variety of analgesic and sedative strategies to provide patient comfort during reduction.

OBJECTIVE

This narrative review evaluates hematoma block, intra-articular injection, intravenous regional analgesia (IVRA) (also known as the Bier block), and periosteal block for orthopedic analgesia in the ED setting.

DISCUSSION

Analgesia is an essential component of management of orthopedic injuries, particularly when reduction is necessary. Options in the ED setting include hematoma blocks, intra-articular injections, IVRA, and periosteal blocks, which provide adequate analgesia without procedural sedation or opioid administration. When used in isolation, these analgesic techniques decrease complications from sedation and the need for other medications, such as opioids, while decreasing ED length of stay. Emergency clinicians can also use these techniques as analgesic adjuncts. However, training in these techniques is recommended prior to routine use, particularly with IVRA.

CONCLUSIONS

Knowledge of analgesic techniques for orthopedic procedures can assist clinicians in optimizing patient care.

Recent Research Advances in Nano-Based Drug Delivery Systems for Local Anesthetics

From a clinical perspective, local anesthetics have rather widespread application in regional blockade for surgery, postoperative analgesia, acute/chronic pain control, and even cancer treatments. However, a number of disadvantages are associated with traditional local anesthetic agents as well as routine drug delivery administration ways, such as neurotoxicity, short half-time, and non-sustained release, thereby limiting their application in clinical practice. Successful characterization of drug delivery systems (DDSs) for individual local anesthetic agents can support to achieve more efficient drug release and prolonged duration of action with reduced systemic toxicity. Different types of DDSs involving various carriers have been examined, including micromaterials, nanomaterials, and cyclodextrin. Among them, nanotechnology-based delivery approaches have significantly developed in the last decade due to the low systemic toxicity and the greater efficacy of non-conventional local anesthetics. Multiple nanosized materials, including polymeric, lipid (solid lipid nanoparticles, nanostructured lipid carriers, and nanoemulsions), metallic, inorganic non-metallic, and hybrid nanoparticles, offer a safe, localized, and long-acting solution for pain management and tumor therapy. This review provides a brief synopsis of different nano-based DDSs for local anesthetics with variable sizes and structural morphology, such as nanocapsules and nanospheres. Recent original research utilizing nanotechnology-based delivery systems is particularly discussed, and the progress and strengths of these DDSs are highlighted. A specific focus of this review is the comparison of various nano-based DDSs for local anesthetics, which can offer additional indications for their further improvement. All in all, nano-based DDSs with unique advantages provide a novel direction for the development of safer and more effective local anesthetic formulations.

A Novel Scale to Assess Parental Satisfaction of Dental Local Anesthetic Techniques in Children: A Cross-Sectional Study

Background

Pain control is one of the most important aspects that can affect parental satisfaction of the dental care provided for children. Dental local anesthesia has the highest impact on pain sensation of the children. However, there is no scale in the literature to assess parental satisfaction of dental local anesthetic techniques.

Objectives

This study was aimed to assess the parental satisfaction with dental local anesthetic techniques for their children through designing a scale that reflects satisfaction and to study the validity and reliability of this scale.

Methods

A cross-sectional observational study was conducted on 150 parents (102 mothers and 48 fathers). Two techniques of local anesthesia were used for each child participated in this study (inferior alveolar nerve block and computerized intraosseous anesthesia). The developed scale consisted of 20 items in a 5-point Likert scale. Half of the items were written in a negative format. Internal consistency, validity, and factor analysis were performed in this study. Independent t-test was used to compare between the two techniques of anesthesia, between boys and girls and among fathers and mothers.

Results

Parental satisfaction mean values were higher in the computerized intraosseous anesthesia group in comparison to inferior alveolar nerve block (P value <0.05). The T-test showed that there was no difference between boys and girls regarding parental satisfaction (P value >0.05). Furthermore, fathers show lower satisfaction in the computerized interosseous anesthesia group (P value <0.05). Excellent internal consistency of this scale was resulted as Cronbach's alpha reliability coefficient was 0.985. After factor analysis, seven factor components were retained by using varimax rotation.

Conclusions

Findings of this study reported that the designed parental satisfaction of dental local anesthetic techniques scale (PSLAS) is a valid and reliable scale to be used. Moreover, this study showed that parental satisfaction was higher when computerized intraosseous anesthesia was used in comparison to inferior alveolar nerve block.

Ultrasound-guided selective peripheral nerve block compared with the sub-dissociative dose of ketamine for analgesia in patients with extremity injuries

STUDY OBJECTIVE

To compare the analgesic efficacy of ultrasound-guided selective peripheral nerve block (PNB) and sub-dissociative dose ketamine (SDK) for management of acute pain in patients with extremity injuries presenting to the emergency department (ED).

METHODS

This prospective, open-label randomized clinical trial was conducted in the ED of a tertiary care Institute. The patients were provided with either ultrasound-guided selective PNB or SDK. The primary outcome was a reduction in pain in numerical rating scale (NRS) by at least 3 points without rescue analgesia. The secondary outcomes were the need for rescue analgesia, adverse events, and patient satisfaction on either arm.

RESULTS

A total of 111 patients with isolated traumatic extremity injuries were included in the final analysis. The NRS score was significantly lower in the PNB group compared to the SDK group at 30, 60,120, 180-, and 240-min post-intervention [group ∼ time interaction, F (5, 647) = 21.53, p ≤ 0.001]. All the patients in the PNB group exhibited primary outcome (NRS ≥3 reductions) at 30 min post-intervention compared with 36 (65%) in the SDK group [-1.02(-1.422,0.622)]. Rescue analgesia was required in 10 (18%) patients in the SDK group compared to none in the PNB group [0.663(0.277,1.050)]. The decrease in NRS score from baseline at 30 min was significantly higher in PNB groups compared to the SDK group [-2.166(-2.640, -1.692)]. The most common side effect reported in the SDK group was dizziness 35(64%), followed by nausea 15(27%). None of the patients in the PNB group reported any complications. Patient satisfaction was higher in the PNB group than SDK group.

CONCLUSION

The study provides evidence that ultrasound-guided PNB is superior to SDK in terms of its analgesic efficacy in the management of acute pain due to extremity injuries and is associated with higher patient satisfaction. The need for rescue analgesia was significantly less in the PNB group. SDK was associated with a high incidence of dizziness and nausea.

Phlegmasia cerulea dolens causing compartment syndrome

BACKGROUND

Phlegmasia cerulea dolens (PCD) is a rare condition characterized by a severely swollen, cyanotic, blue extremity due to a large proximal (iliofemoral) deep venous thrombosis extending into the collateral veins. Mortality in PCD ranges 20-40%. Due to severely compromised venous drainage, compartment pressures can rapidly increase 16-fold within 6 h, but rarely result in arterial compromise.

CASE REPORT

We present a case of a middle-aged woman with no prior history of deep venous thrombosis, with a blue swollen left leg in intractable severe pain unresponsive to 3 doses of hydromorphone. Her pain was successfully alleviated with IV Lidocaine. Patient was found to have phlegmasia cerulea dolens resulting in compartment syndrome of her left leg. Although the patient initially had no motor function, after catheter-directed thrombolysis and emergent thrombectomy, she regained her motor function and made a full recovery. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Phlegmasia cerulea dolens complicated by severe compartment syndrome is a rare entity. Prompt recognition and treatment are necessary to prevent irreversible limb ischemia and associated morbidity and mortality. IV Lidocaine may be considered as an option for analgesia for such patients.