Pharmacokinetics and systemic toxicity of local anesthetics in children

Comparing the effects of three local anaesthetic agents on cardiac conduction system - A randomised study

Background and Aims

This study aimed to compare the effects of three local anaesthetic (LA) agents, namely bupivacaine, levobupivacaine, and ropivacaine, on the cardiac conduction system as assessed by corrected QT (QTc) and P wave dispersion (PWD) intervals in lower limb orthopaedic surgeries and to find the most suitable LA agent that can be used for a long duration.

Methods

The study included 75 patients with American Society of Anesthesiologists physical status I and II of either gender in the age group of 18-65 years undergoing elective lower limb orthopaedic surgeries under epidural anaesthesia. These were allocated to groups B (bupivacaine), L (levobupivacaine), and R (ropivacaine). We observed blood pressure, heart rate, respiratory rate, PWD, and QTc intervals from baseline value through Holter monitoring, pain assessment by visual analogue scale, and demand and total volume of LA consumed by patient-controlled analgesia devices. The repeated measures of ANOVA were carried out to find the effect of time and time-to-group interaction among the groups across the periods.

Results

On intergroup comparison of QTc and PWD, no significant difference among groups was observed, but on intragroup analysis, a statistically significant increase in QTc and PWD from baseline was observed for each of groups B, L, and R at all time intervals. However, the mean increase in QTc and PWD recorded for Group B was higher than in groups L and R.

Conclusions

Bupivacaine has the maximal tendency to prolong QTc and PWD. All three agents showed comparable haemodynamic effects and time to onset of sensory and motor blockade.

Disposition of levobupivacaine during intraoperative continuous caudal epidural analgesia in a preterm neonate

BACKGROUND

Continuous caudal epidural analgesia used intraoperatively in children is an effective and safe technique. However, in preterm neonates, developmental factors may significantly affect levobupivacaine disposition, leading to variable pharmacokinetics, pharmacodynamics, and potential large-variable systemic toxicity of local anesthetics.

OBJECTIVE

To our knowledge, this is the first case report describing the disposition of levobupivacaine used for intraoperative caudal epidural analgesia in a preterm neonate treated for the postoperative pain profile.

METHOD

4-days old neonate (postmenstrual age 35+5, weight 2140 g) with congenital anal atresia received continuous caudal epidural long-term analgesia (loading dose 1.694 mg/kg, initial infusion 0.34 mg/kg/hour) before correction surgery. The blood samples were obtained at 1.0, 1.5, 6.5, 12, and 36.5 h after the start of epidural infusion. The pharmacokinetic profile of levobupivacaine was determined by using the Stochastic Approximation Expectation Maximization algorithm. COMFORT and NIPS pain scores were used for the assessment of epidural analgesia.

RESULTS

The levobupivacaine absorption rate constant, apparent volume of distribution, apparent clearance, and elimination half-life were 10.8 h-1, 0.9 L, 0.086 L/h, and 7.3 h, respectively.

CONCLUSION

The results confirm our hypothesis of altered pharmacokinetics in the preterm neonate. Therefore, levobupivacaine therapy in these patients should be carefully monitored. Since therapeutic drug monitoring of levobupivacaine is not established in clinical routines, we suggest monitoring the intraoperative pain profile using validated scores.

TRIAL REGISTRATION

EudraCT number: 2020-000595-37.

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.

Levobupivacaine plasma concentrations following repeat caudal anesthetics

AIM

A single caudal anesthetic at the start of lower abdominal surgery is unlikely to provide prolonged analgesia. A second caudal at the end of the procedure extends the analgesia duration but total plasma concentrations may be associated with toxicity. Our aim was to measure total plasma levobupivacaine concentrations after repeat caudal anesthesia in infants and to generate a pharmacokinetic model for prediction of plasma concentrations after repeat caudal anesthesia in neonates, infants and children.

METHODS

Infants undergoing definitive repair of anorectal malformations or Hirschsprung's disease received a second caudal anesthesia at the end of the procedure. Total levobupivacaine concentrations were assayed 3-4 times in the first 6 h after the initial caudal. These data were pooled with data from four studies describing plasma concentrations after levobupivacaine caudal or spinal anesthesia. Population pharmacokinetic parameters were estimated using nonlinear mixed-effects models. Covariates included postmenstrual age and body weight. Parameter estimates were used to simulate concentrations after a repeat levobupivacaine 2.5 mg kg^-1 caudal at 3 or 4 h following an initial levobupivacaine 2.5 mg kg^-1 caudal.

RESULTS

Twenty-one infants (postnatal age 11-32 weeks, gestation 37-39 weeks, weight 5.2-8.6 kg) were included. The measured peak plasma concentration after repeat caudal levobupivacaine 2.5 mg kg^-1 4 h after initial caudal was 1.38 mg L^-1 (95% prediction interval 0.60-2.6 mg L^-1 ) and 3 h after initial caudal was 1.46 mg L^-1 (0.60-2.80) mg L^-1 . Simulation of total plasma concentrations in neonates (7 kg, 57 weeks postmenstrual age) given caudal levobupivacaine 4 h after the initial caudal were 1.76 mg L^-1 (0.68-3.50) mg L^-1 if 2.5 mg kg^-1 levobupivacaine was used and 0.88 mg L^-1 (0.34-1.73) mg L^-1 if 1.25 mg kg^-1 of 0.125% levobupivacaine was used. In simulated older children (20 kg, 6 years), the mean maximum concentration was 1.43 mg L^-1 (0.60-2.70) mg L^-1 if 2.5 mg kg^-1 levobupivacaine was repeated at 3 h.

CONCLUSION

Repeat caudal levobupivacaine 2.5 mg kg^-1 at 3 h after an initial 2.5 mg kg^-1 dose does not exceed the concentration associated with systemic local anesthetic toxicity. In 2.5% of simulated neonates (weight 3.8 kg, PMA 40 weeks), repeat caudal anesthesia demonstrates broaching of the lower concentration limit associated with toxicity at both 3 and 4 h after initial caudal.

Erector spinae plane block for thoracoscopy in a paediatric patient

We present the case of a 9 year old patient with a clinical history of epilepsy and various hospitalizations due to aspirative broncopneumonia among others, who was admitted to our hospital because of septic shock secondary to pneumonia of the lower left lobule associated with a parapneumonic pleural effusion and a complicated clinical course. During her stay, the patient undergoes surgical debridement using video assisted thoracoscopic surgery (VATS) under general anaesthesia and the hydropneumothorax is drained. For the procedure an ecoguided erector spinae plane block is performed and combined with general anaesthesia. On one hand this block permitted reduction of perioperative opioid administration and improved the patient's respiration, on the other hand it permitted avoiding the use of drugs, which can lower seizure threshold and increase the risk of convulsions. This case illustrates the importance of locoregional anaesthesia, a technique on the rise in the field of paediatric anaesthesia.

Plasma bupivacaine levels (total and free/unbound) during epidural infusion in liver resection patients: a prospective, observational study

INTRODUCTION

Liver resection patients may be at an increased risk of local anesthetic (LA) toxicity because the liver is essential for metabolizing LA and producing proteins (mainly α1-acid glycoprotein (AAG)) that bind to it and reduce the free (and pharmacologically active/toxic) levels in circulation. The liver resection itself, manipulation during surgery, and pre-existing liver disease may all interfere with normal hepatic protein synthesis and result in an attenuation of the increased AAG (a positive acute-phase protein) that normally occurs postoperatively. The purpose of this study was to determine whether the AAG response is attenuated postoperatively following liver resection and whether patients approach toxicity thresholds with continuous postoperative epidural infusion of bupivacaine.

METHODS

Prospective, observational study with blood drawn preoperatively, in the postanesthetic care unit, on postoperative day (POD) 2, and prior to discontinuation of epidural analgesia on POD3/POD4. Plasma was analyzed for total and unbound bupivacaine via liquid chromatography-mass spectrometry and AAG via ELISA. Signs/symptoms of local anesthetic systemic toxicity (LAST), pain, and sedation scores were also recorded.

RESULTS

For the 19 patients completed, total plasma bupivacaine was correlated with total administered, but unbound levels were not associated with the total administered. Unlike non-hepatectomy surgery where unbound LA plasma levels remain stable (or decrease) with continuous postoperative epidural administration, we observed an overall increase. Several patients approached toxicity thresholds and 47% reported at least one symptom of LAST, but no epidurals were discontinued because of LAST. In contrast to the AAG response reported following major non-liver surgery where AAG levels increase twofold, we observed a reduction until POD2 and the magnitude was proportional to resection weight.

DISCUSSION

Our results are supported by the literature in suggesting that major liver resection patients may be at an increased vulnerability for LAST. Factors such as the extent of liver disease, resection and intraoperative blood loss should be considered when using continuous postoperative epidural infusion of bupivacaine and vigilance should be used in monitoring, for signs/symptoms of LAST, even for those subtle and non-specific. Future research will be required to verify these findings.

TRIAL REGISTRATION NUMBER

NCT03145805.

Pediatric Perioperative Clinical Pharmacy Practice: Clinical Considerations and Management: An Opinion of the Pediatrics and Perioperative Care Practice and Research Networks of the American College of Clinical Pharmacy

Pediatric perioperative clinical pharmacists are uniquely positioned to provide therapeutic and medication management expertise at a particularly vulnerable transition of care from the preoperative space, through surgery, and postoperative setting. There are many direct-patient care activities that are included in the role of the pediatric perioperative pharmacist, as well as many opportunities to develop effective, optimized, and safe medication use processes. This article outlines many of the areas in which a pediatric perioperative clinical pharmacist may intervene.

A multicenter study to evaluate the pharmacokinetics and safety of liposomal bupivacaine for postsurgical analgesia in pediatric patients aged 6 to less than 17 years (PLAY)

STUDY OBJECTIVE

To evaluate the pharmacokinetics and safety of liposomal bupivacaine in pediatric patients undergoing spine or cardiac surgery.

DESIGN

Multicenter, open-label, phase 3, randomized trial (PLAY; NCT03682302).

SETTING

Operating room.

PATIENTS

Two separate age groups were evaluated (age group 1: patients 12 to <17 years undergoing spine surgery; age group 2: patients 6 to <12 years undergoing spine or cardiac surgery).

INTERVENTION

Randomized allocation of liposomal bupivacaine 4 mg/kg or bupivacaine hydrochloride (HCl) 2 mg/kg via local infiltration at the end of spine surgery (age group 1); liposomal bupivacaine 4 mg/kg via local infiltration at the end of spine or cardiac surgery (age group 2).

MEASUREMENTS

The primary and secondary objectives were to evaluate the pharmacokinetics (eg, maximum plasma bupivacaine concentrations [C_max], time to C_max) and safety of liposomal bupivacaine, respectively.

MAIN RESULTS

Baseline characteristics were comparable across groups. Mean C_max after liposomal bupivacaine administration was lower versus bupivacaine HCl in age group 1 (357 vs 564 ng/mL); mean C_max in age group 2 was 320 and 447 ng/mL for spine and cardiac surgery, respectively. Median time to C_max of liposomal bupivacaine occurred later with cardiac surgery versus spine surgery (22.7 vs 7.4 h). In age group 1, the incidence of adverse events (AEs) was comparable between liposomal bupivacaine (61% [19/31]) and bupivacaine HCl (73% [22/30]). In age group 2, 100% (5/5) and 31% (9/29) of patients undergoing spine and cardiac surgery experienced AEs, respectively. AEs were generally mild or moderate, with no discontinuations due to AEs or deaths.

CONCLUSIONS

Plasma bupivacaine levels following local infiltration with liposomal bupivacaine remained below the toxic threshold in adults (~2000-4000 ng/mL) across age groups and procedures. AEs were mild to moderate, supporting the safety of liposomal bupivacaine in pediatric patients undergoing spine or cardiac surgery. Clinical trial number and registry URL: ClinicalTrials.gov identifier: NCT03682302.

Erector spinae catheter for post-thoracotomy pain control in a premature neonate

Ensuring respiratory stability with early tracheal extubation and adequate pain control is challenging in premature neonates after thoracotomy. Continuous erector spinae plane (ESP) block, a relatively new truncal nerve block, has the potential to provide analgesia for thoracic surgeries while reducing opioid use. However, there have been only a few reports utilising this technique in infants, and none in preterm neonates. We present the perioperative pain management of a preterm neonate requiring thoracotomy. Epidural analgesia was deemed contraindicated due to coexisting coagulopathy; therefore, an ESP catheter was placed. The patient was extubated at the end of the surgery and had excellent pain control with rectal acetaminophen, chloroprocaine infusion via the ESP catheter and with minimal opioid requirement. Continuous ESP block may be safe and effective for postoperative pain management in coagulopathic premature neonates. Chloroprocaine is an effective local anaesthetic in the erector spinae compartment, which has not been previously reported.

Exploring the transversus abdominis plane block in cesarean sections and the subsequent toxicity risk to neonates via breast milk

The transversus abdominis plane (TAP) block with its wide application has shown to be an analgesic effective for use in abdominal surgeries, including for cesarean section. However, the bupivacaine delivered in the TAP block comes with the risk of toxicity, both central nerve system (CNS) and cardiovascular system, and has been shown in some instances to reach maximum serum concentrations in excess of the 2 μg/mL associated with the lower end of CNS toxicity. There is a specific concern with cesarean section TAP blocks of the anesthetic passage to the neonate via maternal breast milk and whether this poses a toxicity risk. Bupivacaine has been shown to pass into maternal milk at concentrations 0.34 times the maternal serum concentration. Preliminary statistical analyses suggest that the bupivacaine delivered in breast milk is not in concentrations high enough to cause neonatal toxicity, but further studies would be useful in identifying what the toxicity risk is, if any, to the neonates' breastfeeding after the delivery and TAP block.