Local Anesthetic Plasma Concentrations as a Valuable Tool to Confirm the Diagnosis of Local Anesthetic Systemic Toxicity? A Report of 10 Years of Experience

Comparison of the pharmacokinetic variations of different concentrations of ropivacaine used for serratus anterior plane block in patients undergoing thoracoscopic lobectomy: a population pharmacokinetics analysis

Objective

Ropivacaine serratus anterior plane block is widely used in clinical analgesia in patients undergoing thoracoscopic surgery. Different concentrations of ropivacaine have different analgesic effects, and the safety is highly correlated with the plasma concentration. In this study, the nonlinear mixed effects modeling (NONMEM) method was used to investigate the population pharmacokinetics (PPK) characteristics of ropivacaine and explored the relationship between the covariates on the pharmacokinetic parameters of ropivacaine, in order to provide a theoretical basis for the rational use of ropivacaine.

Methods

This study was approved by the Ethics Committee of the First People's Hospital of Changzhou. The informed consent of patients was obtained. A total of 43 patients who underwent thoracoscopic pneumonectomy in our hospital from April to December 2023 were included. Patients were randomly assigned to four ropivacaine concentration groups of 0.25%, 0.375%, 0.5%, and 0.75%, respectively, and administered with a dose of 3 mg/kg. Arterial blood was taken at 1, 15, 30, 45 min, 1, 2, 4, 8, 12, and 24 h after ropivacaine administration through superficial serratus anterior plane block. The concentration of ropivacaine was detected by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The PPK model was constructed by NONMEM. The final model was verified by using the goodness of fit, visual predictive check (VPC) and normalized predictive distribution error (NPDE). Monte Carlo simulation was applied to evaluate and optimize the dosing regimens.

Results

A total of 388 plasma concentration data from 41 patients were used to establish the model. Eighteen blood concentrations from the other two patients were used for external validation. A two-compartment with zero-order and first-order mixed absorption model was the best model. The proportion of zero-order absorption was 27.4%, the absorption time of zero-order absorption was 0.49 h and the zero-order absorption infusion time was 0.015 h. The first-order absorption rate constant (ka)was correlated with the concentration of ropivacaine. The ka of ropivacaine were 32.0, 19.4 and 14.4 h-1 for 0.25%, 0.5%, and 0.75% ropivacaine, respectively, which indicating that the peak time (Tmax) of low-concentration ropivacaine was significantly shortened. Other pharmacokinetic parameters results were as follows: CL/F(L/h) = 7.475, Vc/F(L) = 125, Q/F(L/h) = 14.7, Vp/F(L) = 197. In addition, the platelet count has an effect on the Vc/F. The simulation results demonstrate the total dose of ropivacaine is recommended not to exceed 300 mg to avoid the occurrence of adverse reactions.

Conclusion

This is the first population pharmacokinetic study of ropivacaine superficial serratus anterior plane block in patients undergoing thoracoscopic pulmonary resection. The model exhibits excellent stability and reliability, thereby offering valuable insights into personalized clinical drug administration. The concentration of ropivacaine and platelet count have significant impacts on the pharmacokinetic parameters of ropivacaine.

Comparison of the effectiveness of two different concentrations of ropivacaine for intrapleural analgesia in reducing stimulatory pain caused by chest tubes after uniportal video-assisted thoracoscopic surgery: a randomised controlled study

BACKGROUND

Pain caused by chest tube placed after uniportal video-assisted thoracoscopic surgery (UVATS) is often neglected. Ropivacaine can be used to alleviate pain related to the chest tube, but the current lowest effective concentration of ropivacaine remains unclear.

METHODS

To investigate the analgesic effect of administering two different concentrations of ropivacaine into the pleural cavity via pleural drainage tube bypass after UVATS. Ninety patients were randomly divided into three groups: Control group (PCIA only), Low-dose group (PCIA combined with intrathoracic infusion of 200 ml 0.25% ropivacaine), Medium-dose group (PCIA combined with intrathoracic infusion of 200 ml 0.5% ropivacaine). The analysis included Visual Analogue Scale (VAS) scores for chest tube-related pain and surgical incision pain at 6 h, 12 h, 24 h, and 48 h post-operation for each group. Compare incidence of adverse reactions (respiratory depression, hypotension, nausea/vomiting, arrhythmia, dizziness) within 48 h.

RESULTS

Compared to the control group, both 0.25% and 0.50% ropivacaine effectively reduced chest tube-related pain (P < 0.001) and surgical incision pain (P < 0.001) at 6 h, 12 h, 24 h, and 48 h postoperatively. However, no significant differences were observed between the two concentrations of ropivacaine in alleviating rest and cough pain related to the chest tube (P > 0.05) or surgical incision (P > 0.05) within 48 h postoperatively. Adverse reaction rates were similar among groups within 48 h postoperatively (P = 0.383).

CONCLUSION

The analgesic effect of ropivacaine infusion with concentrations of 0.25% and 0.50% administered via intrathoracic pumps for chest tube-related pain after UVATS showed no significant difference, but both were superior to the sole use of PCIA.

REGISTRATION

Chinese Clinical Trial Registry ChiCTR2200065184.

The Study of Ropivacaine Pharmacokinetics in a Clinical Setting: A Critical Scoping Review from the Perspective of Analytical Methodologies

Ropivacaine, a widely used regional anesthetic also used for pain management, has been increasingly used in recent years due to its increased efficacy and improved safety compared to similar anesthetics. Biomonitoring of ropivacaine and its metabolites during and after anesthesia is an essential process for ensuring therapeutic efficacy and safe usage for patients. The most useful biomonitoring tool in recent years has been liquid chromatography coupled with mass spectrometry (LC-MS/MS), which offers selectivity, sensitivity, as well as accuracy of measurements. The current manuscript summarizes and discusses the existing liquid chromatographic methods described in the literature, as well as the personal experience with developing bioanalytical and analytical methods for the quantification of ropivacaine in biological samples for clinical applications. It is focused on methodological aspects, recent advancements, challenges, and future perspectives, highlighting the importance of LC-MS/MS techniques in ropivacaine analysis.

The preventive efficacy of lipid emulsion on the occurrence of local anesthetic systemic toxicity in patients receiving local infiltration analgesia for total joint arthroplasty

BACKGROUND

Motor-sparing local infiltration analgesia (LIA) enhances recovery after total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, LIA can induce local anesthetic systemic toxicity (LAST), sometimes necessitating rescue lipid emulsion therapy. Our institute initiated a pilot study to pretreat patients with lipid emulsion (SMOFlipid®) to test its efficacy in mitigating LIA-induced LAST events.

METHODS

This retrospective study enrolled 1,621 adult patients who received LIA with bupivacaine (2-3 mg/kg, maximum 300 mg) for unilateral primary THA or TKA under general anesthesia between January 2020 and April 2022. A total of 439 patients received lipid pretreatment, while 1,182 did not. Demographics, surgical and anesthesia profiles, along with LAST events affecting the neurological, cardiovascular, and respiratory systems, were compared after propensity score matching for age, sex, body mass index (BMI), and surgery type.

RESULTS

The incidence of severe LAST events requiring rescue lipid emulsion slightly decreased after lipid pretreatment (from 2.54 to 2.28 per 1000). Lipid pretreatment significantly reduced the incidence of bradycardia and new-onset arrhythmia (odds ratio: 0.13, adjusted p-value: 0.024) but increased postoperative opioid requirement (odds ratio: 1.71, adjusted p-value: 0.032) after Benjamini-Hochberg correction for multiplicity.

CONCLUSIONS

The efficacy of lipid pretreatment (SMOFlipid® 1.5 ml/kg, maximum 100 ml) in mitigating LIA-induced LAST remains controversial. While lipid pretreatment reduced the incidence of new-onset arrhythmia, it showed no clear benefits for neurologic and respiratory outcomes. Additionally, lipid pretreatment might hinder postoperative recovery by increasing the need for rescue opioid analgesia. Further prospective pharmacokinetic studies are required to assess plasma bupivacaine concentrations following LIA and lipid pretreatment, examine their relationship to LAST events, and establish the efficacy and safety of lipid pretreatment.

Evaluating the efficacy and safety of perianal injection of liposomal ropivacaine HR18034 for postoperative analgesia following hemorrhoidectomy: A multicenter, randomized, double-blind, controlled phase II clinical trial

STUDY OBJECTIVE

HR18034, composed of the ropivacaine encapsulated in multi-lamellar, concentric circular structure liposomes as the major component and a small amount of free ropivacaine, has performed well in animal experiments and phase I clinical trials. This trial was to investigate the efficacy, safety, pharmacokinetic profile and the minimum effective dose of HR18034 for postoperative analgesia after hemorrhoidectomy compared with ropivacaine.

DESIGN

A multicenter, randomized, double-blind trial.

SETTING

19 medical centers in China.

PATIENTS

85 patients undergoing hemorrhoidectomy between October 2022 to November 2022.

INTERVENTIONS

Patients were randomly divided into HR 18034 190 mg group, 285 mg group, 380 mg group and ropivacaine 75 mg group, receiving single local anesthetic perianal injection for postoperative analgesia.

MEASUREMENTS

The primary outcome was the area under the resting state NRS score -time curve within 72 h after injection. The second outcomes included the proportion of patients without pain, the proportion of patients not requiring rescue analgesia, cumulative morphine consumption for rescue analgesia, etc. Safety was evaluated by adverse events incidence and plasma ropivacaine concentrations were measured to explore the pharmacokinetic characteristics of HR18034.

MAIN RESULTS

The areas under the NRS score (at rest and moving states)-time curve were significantly lower in HR 18034 380 mg group than ropivacaine 75 mg at 24 h, 48 h, and 72 h after administration. However, this superiority was not observed in HR18034 190 mg group and 285 mg group. There was no difference in cumulative morphine consumption for rescue analgesia between HR 18034 groups and ropivacaine group.

CONCLUSIONS

HR 18034 380 mg showed superior analgesic efficacy and equivalent safety compared to ropivacaine 75 mg after hemorrhoidectomy, thus preliminarily determined as minimum effective dose.

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.

Association of free maternal and fetal ropivacaine after epidural analgesia for intrapartum caesarean delivery: a prospective observational trial

BACKGROUND

Ropivacaine is present in plasma in both protein-bound and free forms. The free form is responsible for the occurrence of toxic side effects. During obstetric epidural analgesia, free ropivacaine enters the fetal circulation depending on various factors. The aim of this study was to analyse a potential association between ropivacaine concentrations in maternal and fetal plasma and hence the extent of fetal exposure to ropivacaine.

METHODS

In this prospective monocentre study, parturients who met the following criteria were included in the study: 1. epidural administration as part of obstetric anaesthesia, and 2. subsequent intrapartum caesarean delivery, which 3. was performed after an epidural bolus administration of ropivacaine within the existing epidural analgesia. Total and free ropivacaine concentrations were analysed in maternal blood at baseline, prior to epidural bolus administration for caesarean delivery, and in maternal and fetal (umbilical venous, oxygenated) blood at delivery. The results are presented as mean ± SD or median (25/75th percentile).

RESULTS

We screened 128 parturients who went into labour at term and requested epidural analgesia, of whom 39 were ultimately included in the study. An intrapartum caesarean delivery was performed after the epidural application of 207 (166/276) mg ropivacaine during an epidural treatment period of 577 (360/1010) min. Total and free ropivacaine concentrations were 1402 ± 357 ng/ml and 53 ± 46 ng/ml, respectively, in maternal venous blood and 457 ± 243 ng/ml and 43 ± 27 ng/ml, respectively, in fetal blood. The maternal total and free ropivacaine concentrations were significantly correlated (r = 0.873; P < 0.0001).

CONCLUSION

The results of the present study suggest that determining the concentration of free ropivacaine in maternal blood may be a feasible option for estimating neonatal exposure to ropivacaine.

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.

Comparative Study of Pain-Related Responses of Male Piglets up to Seven Days of Age to the Application of Different Local Anaesthetics and Subsequent Castration

Simple Summary

Since 2021, surgical piglet castration must be performed with complete pain elimination according to the Animal Protection Law in Germany. General anaesthesia by isoflurane inhalation, which can be performed by the farmer, or by injection of ketamine and azaperone, which must be performed by a veterinarian, are the options available. At present, local anaesthesia is still under debate because of the lack of proof of complete pain elimination and the pain on injection. We tested three local anaesthetics (procaine, lidocaine, and mepivacaine) at two different doses each. Because pain responses can be masked by reactions caused by handling, the piglets were given superficial isoflurane anaesthesia. The pain on injection to the testes was compared with intramuscular injection, and the effectiveness during castration was compared among the local anaesthetics. Nocifensive movements, respiratory rate, blood pressure, heart rate and its variability as well as electroencephalography (EEG) changes were studied in relation to the painful interventions. Most indicators of nociception point to testicular injection pain being beyond intramuscular injection pain when an effective amount of local anaesthetic was used. However, complete pain elimination could not be achieved during castration under local anaesthesia.

Abstract

To evaluate pain responses to intratesticular and subscrotal injection of three local anaesthetics and their efficacy during castration a randomized controlled study was conducted. In groups of 20 piglets, procaine (2%), lidocaine (2%), or mepivacaine (2%) were administered subscrotal and intratesticularly in two different dosages: 0.5 mL of the original substances or the maximum recommended dosage according to body weight diluted with isotonic saline to a volume of 0.3 mL per each injection site. Two placebo groups received the equivalent volume of isotonic saline. A control group was injected intramuscularly with 0.5 mL isotonic saline for injection pain comparison. Electroencephalographic changes, respiratory rate, heart rate and its variability, blood pressure, and nocifensive movements were assessed in superficial isoflurane anaesthesia. While EEG-changes and linear measures of heart rate variability did not appear conclusive, the low frequency/high frequency (LF/HF) ratio corresponded best with the other pain indicators recorded. The injection of 0.3 mL diluted local anaesthetic per injection site elicited significant fewer signs of pain compared to intramuscular injection of saline. However, pain reduction, but not complete pain elimination, during castration could only be achieved with 0.5 mL of the 2% local anaesthetics per injection site, whereby lidocaine and mepivacaine were the most effective.

Cardiac Arrest after Small Doses Ropivacaine: Local Anesthetic Systemic Toxicity in the Course of Continuous Femoral Nerve Blockade

BACKGROUND

The paper presents a case report of an episode of local anesthetic systemic toxicity (LAST) with cardiac arrest after continuous femoral nerve blockade.

CASE REPORT

A 74-year-old patient burdened with hypertension and osteoarthritis underwent elective total knee replacement surgery. After surgery, a continuous femoral nerve blockade was performed and an infusion of a local anesthetic (LA) was started using an elastomeric pump. Five hours after surgery, the patient had an episode of generalized seizures followed by cardiac arrest. After resuscitation, spontaneous circulation was restored. In the treatment, 20% lipid emulsion was used. On day two of the ICU stay, the patient was fully cardiovascularly and respiratorily stable without neurological deficits and was discharged to the orthopedic department to continue treatment.

CONCLUSION

Systemic toxicity of LA is a serious and potentially fatal complication of the use of LA in clinical practice. It should be noted that in nearly 40% of patients, LAST deviates from the classic and typical course and may have an atypical manifestation, and the first symptoms may appear with a long delay, especially when continuous blockades are used. Therefore, the proper supervision of the patient and the developed procedure in the event of LAST is undoubtedly important here.