Pharmacokinetics of Local Anaesthetics in Infants and Children

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.

To Compare the Effects of Post-tonsillectomy Intra-operative Infiltration of Ropivacaine Versus Bupivacaine in Tonsillar Fossa

Tonsillectomy is one of the most common surgical procedures practiced in Otorhinolaryngology. A significant obstacle for the speedy and smooth recovery is early post- operative pain. Pain leads to negative outcomes such as poor intake, tachycardia, anxiety, delayed wound healing and insomnia. Aim to assess and compare the effect of post-incisional infiltration of 0.75% Ropivacaine v/s 0.5% Bupivacaine on post tonsillectomy pain, the on start of oral intake and stay in hospital and to investigate any complications that can arise due to infiltration of the said drugs. 60 Patients above the age of 5 years were posted for tonsillectomy or adenotonsillectomy under general anesthesia. Patients were blinded about the group in which they will be enrolled. Group A received Inj. ropivacaine (0.75%) 2 ml and Group B: received Inj. Bupivacaine (0.50%) 2 ml in each fossa. After surgery, no analgesics were given & patients were observed for the intensity of post-operative pain in the immediate post-operative period, at 2, 4, 6, 12, 24, 48 h and further if not discharged using VISUAL ANALOGUE SCORE (VAS) and VERBAL RATING SCALE(VRS). Post-operative pain assessment was done using VAS and VRS at 2nd, 4th, 6th, 12th, 24th and 48th hour which was found to be lower in Group 'A'. Patients in Group 'A' also started their oral intake sooner, had lesser hospitalization days than group 'B' patients. Longer time for Rescue analgesic and reduced total dose of analgesic required was seen in Group A compared to Group B. This comparative study on Post-incisional infiltration of 2 ml 0.75% Ropivacaine v/s 2 ml 0.5% Bupivacaine has shown that Ropivacaine is a more effective drug in reducing post-operative pain in comparison to Bupivacaine, proven statistically.

Local Anesthetic Systemic Toxicity in Cardiac Surgery Patient with Erector Spinae Plane Catheter: A Case Report

Regional anesthesia nerve blocks are increasingly used for patients undergoing cardiac surgery as part of multimodal pain management. Though rare, local anesthetic systemic toxicity (LAST) is a severe complication that requires vigilant monitoring. We present a case of a postcardiac surgery patient who developed LAST multiple days after surgery from lidocaine via an erector spinae plane catheter. This episode was determined to be a result of impaired lidocaine metabolism from liver shock caused by worsening pulmonary hypertension. Even under continuous monitoring, patients with cardiac or liver dysfunction are at increased risk of complications from local anesthetics.

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.

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.

Effect of Age and Viscosity on Duration of Corneal Anesthesia with Topical 2% Lidocaine Administration

Purpose: Formulation viscosity and patient-specific parameters such as age are important considerations in achieving patient comfort for prolonged anterior segment surgical procedures. In this study, we report pharmacodynamic and pharmacokinetic parameters of topical 2% lidocaine anesthetic decay based on formulation viscosity and subject age. Methods: Extemporaneous 2% lidocaine solution was compounded with varying percentages of carboxymethylcellulose (CMC) to adjust product viscosity. Juvenile and adult New Zealand White rabbits were utilized as a model for lidocaine-induced corneal anesthesia analysis. Following application of 20 μL in 1 eye of each animal, corneal sensitivity was measured using a Cochet-Bonnet esthesiometer at baseline and at 1-min intervals until recovery to baseline. Subsequent to washout period, the experiment was repeated for 3 replicate experiments. Results: A one-phase exponential decay model was utilized to describe rate of anesthesia decay. Bioavailability increased in a manner disproportionate to both tear film concentration and solution viscosity. In adult animals, half-life of anesthetic decay was found to range from 6.03 min with 2% lidocaine in 0.5% CMC to 9.45 min with 2% lidocaine in 1.5% CMC. In juveniles, half-life was found to be 4.46 and 3.58 min for 2% lidocaine in 1.5% CMC and commercial 2% lidocaine gel, respectively. Conclusions: Decay parameters of lidocaine-induced corneal anesthesia appear disparate from viscosity. It is postulated that viscosity-related increase in corneal contact time through reduced drainage plays a critical role in increasing bioavailability of topical anesthetics in our experimental findings, although nonlinear in character. Age is found to be an important mediator of lidocaine-induced corneal anesthesia.

Transversus abdominis plane block with different bupivacaine concentrations in children undergoing unilateral inguinal hernia repair: a single-blind randomized clinical trial

BACKGROUND

Current knowledge on the ideal local anesthetic concentration for the ultrasound-guided transversus abdominis plane block (TAPB) in pediatrics is scarce. The purpose of this study is to compare the efficacy of US-guided TAPB at two different concentrations of bupivacaine in pediatrics undergoing unilateral inguinal hernia repair.

METHODS

After random allocation, 74 children aged 1-8 were randomized to receive US-guided TAPB by using 1 mg.kg^- 1 bupivacaine as either 0,25% (0,4 ml.kg^- 1) (Group 1) or 0,125% (0,8 ml.kg^- 1) (Group 2) concentration. All blocks were performed under general anesthesia, immediately after the induction, unilaterally with a lateral approach. All subjects received intravenous 15 mg/kg paracetamol 0.15 mg/kg dexamethasone and 0.1 mg/kg ondansetron intraoperatively. The primary outcome was the efficacy which is assessed by postoperative FLACC behavioral pain assessment score at 15', 30', 45', 1 h, 2 h, 6 h, and 24 h. The secondary outcomes were to assess the total dose of rescue analgesic consumption, length of hospital stay, the incidence of side effects, complications and satisfaction levels of the patients' parents and the surgeons.

RESULTS

Sixty-four children were recruited for the study. Postoperative pain scores were equal between the two groups. There was no need for a rescue analgesic in any group after the postoperative 6^thhour. No local or systemic complication or side effect related to anesthesia or surgery was reported.

CONCLUSION

TAPB using 1 mg.kg^- 1 bupivacaine administered as either high volume/low concentration or low volume/high concentration was providing both adequate analgesia and no side effects.

TRIAL REGISTRATION

This trial was retrospectively registered at Clinicaltrals.gov , NCT04202367 .

Evolving approaches in neonatal postoperative pain management

Neonates experience significant moderate and severe postoperative pain. Effective postoperative pain management in neonates is required to minimize acute and long-term effects of neonatal pain. Protecting the developing nervous system from persistent sensitization of pain pathways and developing primary hyperalgesia is essential. Opioids and acetaminophen are commonly analgesics used for pain control. Regional anesthesia provides adequate intraoperative and postoperative analgesia in neonates. It decreases exposure to opioids, reduces adverse drug effects, and facilitates early extubation. It suppresses the stress response and can prevent long-term behavioral responses to pain. The most common blocks performed in neonates are neuraxial blocks. Using ultrasound increased the number of peripheral nerve blocks performed in neonates. Recently, various peripheral nerve blocks (paravertebral, transverse abdominis plane, rectus sheath, quadratus lumborum, erector spinae plane blocks) were safely used. Many studies support analgesic efficacy but highlight neonates' unpredictability and variability of fascial blocks.

Peripheral Nerve Blockade for Medial Patellofemoral Ligament Reconstruction in Pediatric Patients: The Addition of a Proximal Single-Injection Sciatic Nerve Block Provides Improved Analgesia

Purpose

We tested the hypothesis that the addition of a single-injection proximal sciatic nerve block to an adductor canal block would significantly reduce pain scores and opioid requirements compared to a group of patients that received only an adductor canal or femoral nerve block for medial patellofemoral ligament reconstruction in pediatric patients. The primary end-point is the number of patients achieving a Patient Acceptable Symptom State (PASS) (pain score less than four) for the entire 24-hour postoperative period in patients with and without a proximal sciatic block.

Patients and Methods

This is a retrospective cohort study of 144 consecutive pediatric patients, ages 10 to 18 years, undergoing medial patellofemoral ligament reconstruction with peripheral nerve blockade for postoperative analgesia from 2016–2020 at a pediatric orthopedics children’s hospital. Patients were divided into 2 cohorts with and without a proximal sciatic nerve block: group A/F: adductor canal or femoral CPNB and group AS: adductor canal CPNB and a proximal single-injection sciatic nerve block.

Results

There was strong evidence for an increase in the number of patients who reported a pain score less than four for the entire 24-hour postoperative period in the group that received the additional proximal sciatic block. (PASS: A/F 13/62 (21%) vs AS 43/82 (52%), p<0.001) There was strong evidence for a reduction in mean and maximum pain scores and opioid requirements in the first 24-hours after surgery in the proximal sciatic group.

Conclusion

The addition of a proximal sciatic nerve block was associated with significantly reduced mean and maximum pain scores and opioid requirements after medial patellofemoral ligament reconstruction in pediatric patients and supports a randomized clinical trial to confirm these findings. Based on the results of this study we recommend the addition of a proximal sciatic nerve block, anterior or posterior, to an adductor canal block to provide improved analgesia and reduced opioid requirements in the 24-hours after MPFLR in pediatric patients.

Sensitivity of turtles to anticoagulant rodenticides: Risk assessment for green sea turtles (Chelonia mydas) in the Ogasawara Islands and comparison of warfarin sensitivity among turtle species

Although anticoagulant rodenticides (ARs) are effectively used for the control of invasive rodents, nontarget species are also frequently exposed to ARs and secondary poisonings occur widely. However, little data is available on the effects of ARs, especially on marine organisms. To evaluate the effects of ARs on marine wildlife, we chose green sea turtles (Chelonia mydas), which are one of the most common marine organisms around the Ogasawara islands, as our primary study species. The sensitivity of these turtles to ARs was assessed using both in vivo and in vitro approaches. We administered 4 mg/kg of warfarin sodium either orally or intravenously to juvenile green sea turtles. The turtles exhibited slow pharmacokinetics, and prolongation of prothrombin time (PT) was observed only with intravenous warfarin administration. We also conducted an in vitro investigation using liver microsomes from green sea turtles, and two other turtle species (softshell turtle and red-eared slider) and rats. The cytochrome P450 metabolic activity in the liver of green sea turtles was lower than in rats. Additionally, vitamin K epoxide reductase (VKOR), which is the target enzyme of ARs, was inhibited by warfarin in the turtles at lower concentration levels than in rats. These data indicate that turtles may be more sensitive to ARs than rats. We expect that these findings will be helpful for sea turtle conservation following accidental AR-broadcast incidents.

Vorteile, Sicherheit und Nebenwirkungen der Tumeszenz‐Lokalanästhesie bei dermatologischen Operationen an Säuglingen

Die Tumeszenz-Lokalanästhesie (TLA) spielt bei dermatochirurgischen Eingriffen eine wichtige Rolle. Die TLA bietet etliche Vorteile, wie lang anhaltende Betäubung, reduzierte Blutung während der Operation und Vermeidung möglicher Komplikationen einer Vollnarkose. Einfache Durchführung, günstiges Risikoprofil und breites Indikationsspektrum sind weitere Gründe dafür, dass TLA zunehmend auch bei Säuglingen eingesetzt wird. Es gibt nicht nur viele Indikationen für chirurgische Exzisionen im Säuglingsalter, wie angeborene Naevi, sondern es hat auch erhebliche Vorteile, wenn diese Exzisionen in einem frühen Alter durchgeführt werden. Dazu zählen die geringere Größe der Läsionen sowie die unproblematische Wundheilung und Geweberegeneration im Säuglingsalter. Dennoch müssen hinsichtlich der Anwendung der TLA bei Säuglingen einige Aspekte berücksichtigt werden, darunter die Dosierung, eine veränderte Plasmaproteinbindung und die Notwendigkeit einer adäquaten und lang anhaltenden Schmerzkontrolle.

Benefits, safety and side effects of tumescent local anesthesia in dermatologic surgery in infants

Tumescent local anesthesia (TLA) plays an important role in dermatosurgical procedures. TLA has several benefits such as long-lasting anesthesia, reduced bleeding during surgery and the avoidance of general anesthesia-associated complications. Convenience and a favorable risk profile along with a broad spectrum of indications are further reasons why TLA is increasingly applied in infants as well. There are not only a variety of indications for surgical excisions in infancy, such as congenital nevi, but also substantial benefits when performing these excisions at an early age. These include the smaller size of the lesions as well as the unproblematic wound healing and tissue regeneration in infancy. Nevertheless, several aspects need to be considered when applying TLA in infants including dosing, altered plasma protein binding and the need for adequate and long-lasting pain control.

Population pharmacokinetics of ropivacaine used for local infiltration anaesthesia during primary total unilateral and simultaneous bilateral knee arthroplasty

BACKGROUND

Ropivacaine is commonly used in local infiltration anaesthesia (LIA) as pain management after total knee arthroplasty (TKA). Although considered safe, no studies evaluated the pharmacokinetics of high-dose ropivacaine infiltration in simultaneous bilateral TKA.

METHODS

We studied 13 patients undergoing unilateral and 15 undergoing bilateral TKA. Standard LIA technique was used with ropivacaine 0.2%, 200 ml (400 mg) injected peri-articularly in each knee. Free and total plasma concentrations of ropivacaine were measured within 24 h using liquid chromatography-mass spectrometry. A population pharmacokinetic model was built using non-linear mixed-effects models.

RESULTS

Peak free ropivacaine concentration was 0.030 (0.017-0.071) μg ml^-1 (mean [99% confidence interval]) vs 0.095 (0.047-0.208) μg ml^-1, and peak total ropivacaine concentration was 0.756 (0.065-1.222) μg ml^-1vs 1.695 (0.077-3.005) μg ml^-1 for unilateral and bilateral TKA, respectively. The pharmacokinetics was ascribed a one-compartment model with first-order absorption. The main identified covariates were protein binding, allometrically scaled body weight on clearance and volume, and unilateral or bilateral surgery on volume.

CONCLUSIONS

This is the first study to investigate the pharmacokinetics of free and total ropivacaine after unilateral and bilateral TKA. A population model was successfully built and peak free ropivacaine concentration stayed below previously proposed toxic thresholds in patients undergoing unilateral and bilateral TKA receiving LIA with high-dose ropivacaine.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04702282.

Personalized pediatric anesthesia and pain management: problem-based review

Pharmacogenetics, the genetic influence on the interpersonal variability in drug response, has enabled tailored pharmacotherapy and emerging 'personalized medicine.' Although oncology spearheaded the clinical implementation of personalized medicine, other specialties are rapidly catching up. In anesthesia, classical examples of genetically mediated idiosyncratic reactions have been long known (e.g., malignant hyperthermia and prolonged apnea after succinylcholine). The last two decades have witnessed an expanding body of pharmacogenetic evidence in anesthesia. This review highlights some of the prominent pharmacogenetic associations studied in anesthesia and pain management, with special focus on pediatric anesthesia.

A Review of Regional Anesthesia in Infants

Regional anesthesia provides effective anesthesia and pain relief in infants with age-specific data attesting to safety and efficacy. Regional anesthesia decreases exposure to opioids and general anesthetic agents and associated adverse drug effects, suppresses the stress response, and provides better hemodynamic stability compared to general anesthesia. Regional anesthesia can prevent long-term behavioral responses to pain. As a result, the overall number and variety of nerve blocks being used in infants is increasing. While neuraxial blocks are the most common blocks performed in infants, the introduction of ultrasound imaging and a better safety profile has advanced the use of peripheral nerve blocks. Infant-specific pharmacokinetic and pharmacodynamic data of local anesthetic medications are reviewed including risk factors for the accumulation of high serum levels of unbound, pharmacologically active drug. Bupivacaine accumulates with continuous infusion and 2-chloroprocaine can be used as an alternative. Local anesthetic systemic toxicity has the highest incidence in infants less than 6 months of age and is associated with bolus dosing and penile nerve blocks. Local anesthetic toxicity is treated by securing the airway, suppression of seizure activity and implementation of cardiopulmonary resuscitation. Administration of intralipid (intravenous lipid emulsion) is initiated at the first sign of toxicity. A high level of expertise in regional anesthesia is needed when treating infants due to their unique development.

Transversus Abdominal Plane Block in Children: Efficacy and Safety: A Randomized Clinical Study and Pharmacokinetic Profile

BACKGROUND

The transversus abdominis plane (TAP) block has become a common regional anesthesia technique for pain management in a wide variety of abdominal procedures. Evidence to support any particular local anesthetic regimen as well as pharmacokinetic and systemic toxicity risks of TAP block remain insufficiently studied in children. The aim of this study was to compare the analgesic effects and investigate pharmacokinetic profile of levobupivacaine after ultrasound-guided TAP block using a low volume/high concentration (LVHC) or a high volume/low concentration (HVLC) solution in children.

METHODS

This prospective randomized study included children scheduled for day-case inguinal surgery. Children were randomized to receive TAP block using 0.4 mg·kg levobupivacaine as either HVLC (0.2 mL·kg of 0.2% levobupivacaine) or LVHC (0.1 mL·kg of 0.4% levobupivacaine). The primary outcome was the number of children who required opioid rescue analgesia postoperatively. Pharmacokinetic profile study of levobupivacaine was also performed.

RESULTS

Seventy patients were equally randomized, and 65 were included in the final analysis. Seventy-one percent of patients did not require any postoperative opioid analgesia. The number of patients who received rescue analgesia was 12 (35%) in the LVHC group and 7 (23%) in the HVLC group (relative risk, 0.64; 95% confidence interval [CI], 0.29-1.42; P = .26). Mean pain scores (FLACC [faces, legs, activity, cry, and consolability]) at postanesthesia care unit discharge did not differ between LVHC and HVLC groups, respectively, 0.39 ± 0.86 and 1 ± 1.71 with mean group difference -0.60 (95% CI, -1.27 to 0.06; P = .08). The pharmacokinetic profile of levobupivacaine was comparable in the 2 groups: the mean total and free levobupivacaine peak concentrations were 379 ± 248 and 3.95 ± 3.16 ng·mL, respectively, occurring 22.5 ± 11 minutes after injection. The highest total and free levobupivacaine concentrations collected, respectively, 1360 and 15.1 ng·mL, remained far below theoretical toxic thresholds.

CONCLUSIONS

In children, quality of postoperative pain control provided by TAP block using levobupivacaine 0.4 mg·kg administered as either HVLC or LVHC did not differ and was associated with a very low risk of local anesthetic systemic toxicity.

Neuroprotective potential of ketamine prevents developing brain structure impairment and alteration of neurocognitive function induced via isoflurane through the PI3K/AKT/GSK-3β pathway

Background

The aim of the current experimental study was to scrutinize the neuroprotective effect of ketamine on the isoflurane (iso)-induced cognitive dysfunction in rats via phosphoinositide 3 kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase 3β (GSK-3β) pathway.

Materials and methods

Sprague-Dawley rats were used for the current experimental study. The rats were divided into six groups and rats were treated with ketamine and memantine. For the estimation of cognitive function study, we used the Morris water test. Pro-inflammatory cytokines such as IL-1β, IL-6, tumor necrosis factor-α (TNF-α), and caspase-6; the antioxidant parameters malondialdehyde, glutathione, superoxide dismutase, catalase, and protein carbonyl; acetylcholinesterase, amyloid β, and brain-derived neurotrophic factor were estimated, respectively. The protein expression of AKT, GSK-3β, p21WAF1/CIP1, and p53 was also estimated, respectively.

Results

Ketamine significantly enhanced cognitive function and showed anti-inflammatory and antioxidant effects, and exhibited the neuroprotective effect of ketamine against the isoflurane-induced cognitive impairment. Additionally, ketamine significantly (P<0.005) suppressed IL-1β, TNF-α, IL-6, caspase-6 and p21WAF1/CIP1, p53 expression and up-regulated the PI3K/AKT/GSK-3β expression in the group of iso-induced rats.

Conclusion

We can conclude that ketamine prevented the cognitive impairment induced by isoflurane anesthesia through anti-apoptotic, anti-inflammatory, and antioxidant effects via the PI3K/AKT/GSK-3β pathway.

Peribulbar block combined with general anesthesia in babies undergoing laser treatment for retinopathy of prematurity: a retrospective analysis

Background and objectives

Currently there is no agreement regarding which one is the most adequate anesthetic technique for the treatment of retinopathy of prematurity. Peribulbar block may reduce the incidence of oculocardiac reflex and postoperative apnea. The goal of this study was to report the outcomes of peribulbar block, when combined with general anesthesia, for the laser treatment for retinopathy of prematurity, in premature babies.

Methods

A retrospective analysis of anesthetic records of all babies who underwent laser treatment for retinopathy of prematurity from January 2008 through December 2015 in a tertiary hospital was performed.

Results

During that period a total of six babies was submitted to laser treatment for retinopathy of prematurity, all under peribulbar block combined with general anesthesia. A single infratemporal injection of 0.15 mL.kg⁻¹ per eye ropivacaine 1% or 0.75% was performed. At the end of the procedure, all babies resumed spontaneous ventilation. No perioperative complications were reported.

Conclusions

Peribulbar block was a safe anesthetic technique in our sample considered.

Postoperative pain management in children: Guidance from the pain committee of the European Society for Paediatric Anaesthesiology (ESPA Pain Management Ladder Initiative)

The main remit of the European Society for Paediatric Anaesthesiology (ESPA) Pain Committee is to improve the quality of pain management in children. The ESPA Pain Management Ladder is a clinical practice advisory based upon expert consensus to help to ensure a basic standard of perioperative pain management for all children. Further steps are suggested to improve pain management once a basic standard has been achieved. The guidance is grouped by the type of surgical procedure and layered to suggest basic, intermediate, and advanced pain management methods. The committee members are aware that there are marked differences in financial and personal resources in different institutions and countries and also considerable variations in the availability of analgesic drugs across Europe. We recommend that the guidance should be used as a framework to guide best practice.

[Peribulbar block combined with general anesthesia in babies undergoing laser treatment for retinopathy of prematurity: a retrospective analysis]

BACKGROUND AND OBJECTIVES

Currently there is no agreement regarding which one is the most adequate anesthetic technique for the treatment of retinopathy of prematurity. Peribulbar block may reduce the incidence of oculocardiac reflex and postoperative apnea. The goal of this study was to report the outcomes of peribulbar block, when combined with general anesthesia, for the laser treatment for retinopathy of prematurity, in premature babies.

METHODS

A retrospective analysis of anesthetic records of all babies who underwent laser treatment for retinopathy of prematurity from January 2008 through December 2015 in a tertiary hospital was performed.

RESULTS

During that period a total of six babies was submitted to laser treatment for retinopathy of prematurity, all under peribulbar block combined with general anesthesia. A single infratemporal injection of 0.15mL.kg^-1 per eye ropivacaine 1% or 0.75% was performed. At the end of the procedure, all babies resumed spontaneous ventilation. No perioperative complications were reported.

CONCLUSIONS

Peribulbar block was a safe anesthetic technique in our sample considered.

Infant spinal anesthesia: Do girls need a larger dose of local anesthetic?

BACKGROUND

Gender differences in absorption, distribution, and metabolism of a number of anesthetic agents have been identified in adults. Clinically, adult studies suggest women demonstrate slower onset of opioid analgesic effects, lower spinal and epidural dose requirements, and greater sensitivity to neuromuscular blocking agents. Sex-related differences in the pharmacokinetics and pharmacodynamics of local anesthetics in neonates and infants, however, have not been well documented. As a result, it is not known whether modification of the dose of local anesthetic for awake spinal anesthesia in infants is required.

AIMS

Our aim was to determine whether the ED50 and ED95 of local anesthetics used for infant spinal anesthesia are different between sexes.

METHODS

This was a retrospective analysis of data previously collected during dose-response studies of levobupivacaine and ropivacaine spinal anesthetics. The doses were reanalyzed using generalized linear regression analysis to determine whether there is a discernible difference in dose requirements between male and female infants.

RESULTS

One hundred and twenty infant spinal anesthetics were reviewed. For levobupivacaine, the ED50 (95% CI) was 0.69 (0.49-0.88) mg vs 0.49 (0.33-0.65), whereas the ED95(95% CI) was 1.07 (0.73-1.41) vs 0.93 (0.64-1.22) for girls and boys, respectively. For ropivacaine spinal anesthesia, the ED50 (95% CI) was 0.64 (0.35-0.92) mg vs 0.30 (-0.32-0.92), whereas the ED95 (95% CI) was 1.30 (0.73-1.87) vs 1.66 (0.55-2.76) for girls and boys, respectively.

CONCLUSION

There is no evidence that sex differences occur at the ED50 dose range or at the clinically relevant ED95 dose. Modification of spinal anesthetic dose is not required for infant girls.

Ropivacaine (total and unbound) and AGP concentrations after transversus abdominis plane block for analgesia after abdominal surgery

BACKGROUND

The goal of this study was to assess the safety of single bolus dose of ropivacaine (ROP) followed by continuous infusion through transversus abdominis plane block catheter. The aim was to determine ROP absorbed from the infusion site, changes in protein binding after surgery, and clinical determinants of adverse effects.

METHODS

Twelve patients undergoing laparotomy, received bilateral transversus abdominis plane block under ultrasound guidance using a 20-mL bolus of 0.5% ROP followed by 10 mL/h of 0.2% ROP infusion for 48 hours. Serial blood samples were drawn presurgery and to 48 hours postbolus. Plasma concentrations of total and unbound ROP were measured by high performance liquid chromatography with ultraviolet detection. Alpha-1 acid glycoprotein concentrations were measured by enzyme-linked immunosorbent assay. Patients were monitored for any signs or symptoms of central nervous system and chorionic villus sampling toxicity.

RESULTS

After the bolus dose, the mean (±SD) peak plasma total (bound plus unbound) ROP concentration (Cmax) was 2.1 (±0.8) mg/L and unbound ROP concentration was 0.04 (±0.02) mg/L. During the infusion phase, total ROP concentration continued to rise to a mean (±) Cmax of 3.3 (±1.6) mg/L, and the peak unbound concentration was 0.06 (±0.0) mg/L. No patients showed symptoms of ROP toxicity or unacceptable QTc intervals.

CONCLUSIONS

Although the total ROP concentrations approached or exceeded reported neurotoxicity thresholds, no patients had unbound ROP concentrations approaching the unbound toxicity threshold, nor showed any signs or symptoms of toxicity. This result was consistent with changes in protein binding to alpha-1 acid glycoprotein after surgery.

Elevated lidocaine serum levels following the use of a needle free device in healthy adult volunteers

There is increased concern regarding circulating levels of lidocaine immediately after the use of a needle-free device with buffered lidocaine. As a result, we conducted a prospective study to assess lidocaine circulation after the use of a needle-free device for the delivery of a local anesthetic in 10 healthy adult subjects. After informed consent, 2 peripheral intravenous catheters were placed in the antecubital fossa of each arm. Two milligrams of 1% buffered lidocaine was administered by the study physician via the needle-free device on the dorsum of the subject's hand. Within 2 minutes, a third intravenous catheter was placed in the location of the lidocaine administration and 5 mL of blood was collected from all 3 sites. If blood samples returned positive for lidocaine, they were also collected 1 hour and 2 hours after administration. Toxic levels of lidocaine were found in blood drawn from 2 subjects immediately after lidocaine administration. Results also showed that certain subjects had increasing levels of lidocaine over time. Other subjects also had increasing lidocaine serum levels from blood drawn on the arm opposite the administration site. We concluded that there may be systemic lidocaine levels with the administration of the needle-free device and that these levels may reach the toxic range in adults. Further investigation will be required to determine whether this finding has clinical significance, especially considering the smaller body mass of children.

Bupivacaine and levobupivacaine induce apoptosis in rat chondrocyte cell cultures at ultra-low doses

PURPOSE

Osteoarthritis (OA) is characterized by chondrocyte apoptosis and necrosis which play a key role during the progression of OA. Intra-articular administration of bupivacaine is a practical and effective way of postoperative pain control following various joint surgeries. 0.25 % bupivacaine showed to be safe in terms of chondrocyte toxicity. Around 200 nM of bupivacaine was shown to be effective for peripheral nerve block. This study aims to observe the possible cytotoxic effects of bupivacaine and its enantiomer levobupivacaine on chondrocyte cell culture at 7.69, 76.9, and 384.5 μM or at 0.0125, 0.0025, and 0.00025 % concentrations, respectively.

METHODS

Chondrocytes were isolated from rat articular cartilage after incubating with collagenase in RPMI-1640 medium. Cells were treated with bupivacaine and levobupivacaine at 7.69, 76.9, and 384.5 μM concentrations for 6, 24, and 48 h. Treated chondrocytes were stained with acridine orange and ethidium bromide and examined under a fluorescence microscope at a 490 nm excitation wavelength for apoptotic changes.

RESULTS

Study results suggest that both bupivacaine and levobupivacaine have dose-dependent chondrocyte toxicity, and this is significantly lesser at 7.69 μM dose. There was no significant difference in terms of chondrocyte apoptosis, (p > 0.05).

CONCLUSIONS

Clinicians should be skeptic for the serious long-term side effects of bupivacaine and its analogs, even at ultra-low doses.

Absorption characteristics of epidural levobupivacaine with adrenaline and clonidine in children

AIM

To determine if the addition of adrenaline, clonidine, or their combination altered the pharmacokinetic profile of levobupivacaine administered via the caudal epidural route in children.

METHODS

Children aged <18 years old scheduled to undergo sub-umbilical surgery were administered caudal levobupivacaine plain 2.5 mg · ml(-1) or with adjuvants adrenaline 5 mcg · ml(-1) or clonidine 2 mcg · ml(-1) or their combination. Covariate analysis included weight and postnatal age (PNA). Time-concentration profile analysis was undertaken using nonlinear mixed effects models. A one-compartment linear disposition model with first-order input and first-order elimination was used to describe the data. The effect of either clonidine or adrenaline on absorption was investigated using a scaling parameter (Fabs(CLON), Fabs(ADR)) applied to the absorption half-life (Tabs).

RESULTS

There were 240 children (median weight 11.0, range 1.9-56.1 kg; median postnatal age 16.7, range 0.6-167.6 months). Absorption of levobupivacaine was faster when mixed with clonidine (Fabs(CLON) 0.60; 95%CI 0.44, 0.83) but slower when mixed with adrenaline (Fabs(ADR) 2.12; 95%CI 1.45, 3.08). The addition of adrenaline to levobupivacaine resulted in a bifid absorption pattern. While initial absorption was unchanged (Tabs 0.15 h 95%CI 0.12, 0.18 h), there was a late absorption peak characterized by a Tabs(LATE) 2.34 h (95%CI 1.44, 4.97 h). The additional use of clonidine with adrenaline had minimal effect on the bifid absorption profile observed with adrenaline alone. Neither clonidine nor adrenaline had any effect on clearance. The population parameter estimate for volume of distribution was 157 l 70 kg(-1). Clearance was 6.5 l · h(-1) 70 kg(-1) at 1-month PNA and increased with a maturation half-time of 1.6 months to reach 90% of the mature value (18.5 l · h(-1) 70 kg(-1)) by 5 months PNA.

CONCLUSIONS

The addition of adrenaline decreases the rate of levobupivacaine systemic absorption, reducing peak concentration by half. Levobupivacaine concentrations with adrenaline adjuvant were reduced compared to plain levobupivacaine for up to 3.5 hours. Clonidine as an adjuvant results in faster systemic absorption of levobupivacaine and similar concentration time profile to levobupivacaine alone. Adding adrenaline with clonidine does not alter the concentration profile observed with adrenaline alone.

The effects of levobupivacaine infiltration on post-tonsillectomy pain relief in adults: a single-blinded, randomized, and controlled clinical study

The aim of this prospective single-blinded and controlled study is to evaluate the efficacy of levobupivacaine infiltration on post-tonsillectomy pain relief in adults. The study was conducted with 40 adult patients who underwent tonsillectomy. These patients were randomized in either study group (SG) who received levobupivacaine infiltration to peritonsillary fossae prior to surgery or control group (CG) with no medication. After surgery, all the patients were queried for pain scores by visual analog scale. In addition, the volume of intraoperative bleeding, the duration of operation, the severity of postoperative complications, and the amount of analgesic requirement were the other outcome measures of this study. There were significant differences between groups regarding pain scores for the first 24 h in favor of SG. The analgesic requirement was also significantly lower in SG (p = 0.009). Although there was a sustained decrement at pain score during first 24 h for SG, however, the change from baseline score (immediate score) for each time interval revealed no significance compared to CG. In addition, the duration of operation and the volume of intraoperative bleeding were similar (p = 0.64 and p = 0.165). In conclusion, preincisional infiltration of levobupivacaine is a safe and reliable method for post-tonsillectomy pain reduction in adults. However, more in-depth, double-blinded and placebo controlled studies are required to elucidate its long term benefits.

Articaine: a review of its use for local and regional anesthesia

Articaine is an intermediate-potency, short-acting amide local anesthetic with a fast metabolism due to an ester group in its structure. It is effective with local infiltration or peripheral nerve block in dentistry, when administered as a spinal, epidural, ocular, or regional nerve block, or when injected intravenously for regional anesthesia. In comparative trials, its clinical effects were not generally significantly different from those of other short-acting local anesthetics like lidocaine, prilocaine, and chloroprocaine, and there is no conclusive evidence demonstrating above-average neurotoxicity. Articaine proved to be suitable and safe for procedures requiring a short duration of action in which a fast onset of anesthesia is desired, eg, dental procedures and ambulatory spinal anesthesia, in normal and in special populations.

A neonate with long QT syndrome, refractory ventricular arrhythmias, and lidocaine toxicity

Long QT syndrome is characterized by electrocardiographic appearance of long QT intervals and propensity to polymorphic ventricular tachycardia. Aggressive anticipatory clinical management is required for a good outcome, especially in the symptomatic neonate. We present a neonate with a compound mutation with refractory ventricular tachycardia that necessitated multimodal pharmacotherapy with lidocaine, esmolol, and amiodarone along with ventricular pacing. Despite normal serum lidocaine levels, complex pharmacokinetic interactions resulted in presumed neurotoxicity due to lidocaine. This report discusses the implications and challenges of management of a neonate with compound long mutations.

Toxicity of local anesthetic drugs: a pediatric perspective

The main mechanism of action of local anesthetics (LA) is to block sodium channels, thereby interrupting the propagation of nerve impulses. However, this action not only is localized to the sodium channels of nerve tissues involved with pain transmission but will have its effect on any tissue containing sodium channels. Thus, if there is a rapid absorption into the systemic circulation of locally injected LA or if LA inadvertently is injected into a blood vessel, then significant blockade of sodium channels in other tissues may also be blocked and serious complications may ensue. The two most important tissues associated with systemic toxicity of LA are the central nervous and the cardiovascular systems, which may lead to seizures, tachyarrhythmias, and ultimately death from apnea and cardiovascular collapse. The aim of this communication is to elucidate some issues that are associated with toxicity of LA and its treatment in the pediatric population.

Local anesthetics and their adjuncts

Local anesthetics (LA) block propagation of impulses along nerve fibers by inactivation of voltage-gated sodium channels, which initiate action potentials (1). They act on the cytosolic side of phospholipid membranes. Two main chemical compounds are used, amino esters and amino amides. Amino esters are degraded by pseudocholinesterases in plasma. Amino amides are metabolized exclusively by the liver. Only amide LAs will be considered in this article.

Persistent hiccups associated with epidural ropivacaine in a newborn

OBJECTIVE

To report a case of persistent hiccups associated with epidural ropivacaine in a newborn infant.

CASE SUMMARY

A term female infant (3.05 kg) received epidural ropivacaine for pain control during and after an operative procedure to correct a tracheoesophageal fistula. Three intermittent doses of ropivacaine were administered during the operative period (total dose 2.29 mg/kg) followed by a continuous epidural (caudal) infusion (0.1% ropivacaine; initial dose 0.23 mg/kg/h plus fentanyl 0.46 μg/kg/h). The infant was extubated in the recovery area and transferred to the intensive care unit. Within hours of transfer, she developed persistent hiccups. The epidural infusion was titrated for pain control, up to 0.32 mg/kg/h (ropivacaine). The hiccup frequency increased to every 10-30 seconds, with the patient appearing hypotonic with lip trembling and intermittent tongue fasciculation. An electroencephalogram did not show any epileptiform activity or focal features consistent with seizure activity. The epidural infusion was reduced to 0.26 mg/kg/h (ropivacaine), with dramatic improvement in hiccups and tone. The infusion was discontinued and complete resolution of hiccups was observed.

DISCUSSION

Ropivacaine is commonly used for infiltration anesthesia and peripheral and epidural block anesthesia. Use of the Naranjo probability scale determined that our patient's hiccups were probably caused by ropivacaine. To our knowledge, this is the first report of persistent hiccups associated with epidural ropivacaine.

CONCLUSIONS

Clinicians should consider the potential of neurotoxicity, manifested as persistent hiccups, when epidural ropivacaine is administered to young infants.

Comparison of peritonsillar levobupivacaine and bupivacaine infiltration for post-tonsillectomy pain relief in children: placebo-controlled clinical study

OBJECTIVES

To compare the effects of preincisional peritonsillar infiltration of levobupivacaine and bupivacaine on post-tonsillectomy pain in children.

METHODS

Sixty children undergoing elective tonsillectomy or adenotonsillectomy were randomly allocated into three groups before tonsillectomy: peritonsillar infiltrations with 0.25% levobupivacaine with 1:200,000 epinephrine (group levobupivacaine, n=20), 0.25% bupivacaine with 1:200,000 epinephrine (group bupivacaine, n=20), and normal saline (group saline, n=20) were applied. Pain was evaluated by using a modified Children's Hospital of Eastern Ontario Pain Scale (mCHEOPS). Choice of additional analgesic was acetaminophen for all patients.

RESULTS

mCHEOPS values at 0th (immediately) and 30th minute after arrival the PACU were lower in both the local anesthetics groups than the saline group (p<0.001, p<0.01 for the group levobupivacaine; p<0.001, p<0.05 for the group bupivacaine, respectively). In addition, mCHEOPS values at 1st hour in the ward was lower in the group bupivacaine when compared to the group saline (p<0.05). Analgesic requirements and the time to first analgesia required, were also significantly different between the local anesthetic and saline groups (p<0.05 for both local anesthetics groups). Time to first mobilization was shorter in both local anesthetic groups when compared to the saline group (p<0.05 for both local anesthetic groups).

CONCLUSION

Preincisional peritonsillar infiltration with levobupivacaine or bupivacaine before tonsillectomy, are effective than saline, in reducing early post-tonsillectomy pain, where as bupivacaine had slightly longer effect. Compared to saline, with both anesthetic infiltrations, lesser medication for analgesia is required. The clinical trial registration number (Research Ethics Committee of Medical Faculty, Uludag University): 2008-4/36, 19 February 2008.

Population pharmacokinetics of tamsulosin hydrochloride in paediatric patients with neuropathic and non-neuropathic bladder

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Tamsulosin is available on prescription as a modified release capsule in the US (Flomax), and in most European countries for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH). The pharmacokinetics of tamsulosin hydrochloride (HCl) have been extensively studied in adults, but no pharmacokinetic data for paediatrics have been published to date.

WHAT THIS STUDY ADDS

A population pharmacokinetic model of tamsulosin HCl was developed in paediatric patients. Covariate analysis revealed that body weight and alpha(1)-acid glycoprotein influenced both the apparent clearance and the apparent volume of distribution. This study confirms that there is no major difference in the pharmacokinetics of tamsulosin HCl between paediatrics (age range 2-16 years) and adults when the effect of body weight is taken into consideration.

AIMS

The main objective of this study was to characterize the population pharmacokinetics of tamsulosin hydrochloride (HCl) in paediatric patients with neuropathic and non-neuropathic bladder. A secondary objective was to compare the pharmacokinetics in paediatric patients and adults.

METHODS

Tamsulosin HCl plasma concentrations in 1082 plasma samples from 189 paediatric patients (age range 2-16 years) were analyzed with NONMEM, applying a one compartment model with first-order absorption. Based on the principles of allometry, body weight was incorporated in the base model, along with fixed allometric exponents. Covariate analysis was performed by means of a stepwise forward inclusion and backward elimination procedure. Simulations based on the final model were used to compare the pharmacokinetics with those in adults.

RESULTS

Beside the priori-implemented body weight, only alpha(1)-acid glycoprotein had an effect on both apparent clearance and apparent volume of distribution. No other investigated covariates, including gender, age, race, patient population and concomitant therapy with anti-cholinergics, significantly affected the pharmacokinetics of tamsulosin HCl (P < 0.001). The results of simulations indicated that the exposure in 12.5 kg paediatric patients was 3.5-4.3 fold higher than that in 70.0 kg adults. After a weight-based dose administration, the exposure in paediatric patients was comparable with that in healthy adults.

CONCLUSIONS

A population pharmacokinetic model of tamsulosin HCl in paediatric patients was established and it described the data well. There was no major difference in the pharmacokinetics of tamsulosin HCl between paediatric patients (age range 2-16 years) and adults when the effect of body weight was taken into consideration.

The influence of age on bupivacaine cardiotoxicity

BACKGROUND

The susceptibility of children and newborns to cardiotoxicity from racemic bupivacaine, RS(±)-bupivacaine, is controversial. Some studies indicate that newborns can sustain higher bupivacaine plasma levels than adults, without severe toxicity. In this study, we compared the influence of age on cardiotoxicity from RS(±)-bupivacaine and S(-)-bupivacaine in rats. The effects of these local anesthetics (LAs) on the regulation of intracellular Ca(2+) concentrations in cardiac fibers were also investigated.

METHODS

The lethal dose was determined in ventilated male Wistar rats at 2, 4, 8, and 16 weeks of age by monitoring when cardiac electrical activity stopped after infusion of RS(±)-bupivacaine and S(-)-bupivacaine (4 mg · kg(-1) · min(-1)). The effects on cardiac muscle contraction were investigated by in vitro measurement of papillary muscle twitches in the presence and absence of RS(±)-bupivacaine or S(-)-bupivacaine. Skinned ventricular fibers were used to investigate the intracellular effects on Ca(2+) regulation induced by both LAs.

RESULTS

The lethal dose for RS(±)-bupivacaine and S(-)-bupivacaine in 2-week-old animals (46.0 ± 5.2 and 91.3 ± 4.9 mg · kg(-1), respectively) was higher than in 16-week-old animals (22.7 ± 1.3 and 22.0 ± 2.7 mg · kg(-1), respectively). Papillary muscle twitches were reduced in a dose-dependent manner, with significant difference between young and adult hearts. In adults, the muscle twitches were reduced to 8.6% ± 0.8% of control by RS(±)-bupivacaine, and to 18.1% ± 2.7% of control by S(-)-bupivacaine (100 μM). S(-)-bupivacaine had a positive inotropic effect at <10 μM, but only in 2-week-old animals. In chemically skinned ventricular fibers, RS(±)-bupivacaine and S(-)-bupivacaine induced similar increases in Ca(2+) release from the sarcoplasmic reticulum (SR) preactivated with caffeine (1 mM), and this effect was greater in younger rats than adults. In 16-week-old rats, caffeine-induced tension was 53.9% ± 1.7% of the maximal fiber response with RS(±)-bupivacaine, and 54.1% ± 3.2% with S(-)-bupivacaine. The caffeine response in 2-week-old rats was 81.1% ± 3.7% of the maximal response with RS(±)-bupivacaine, and 78.1% ± 4.5% with S(-)-bupivacaine. The Ca(2+) sensitivity of contractile proteins was equally increased at both ages tested, with RS(±)-bupivacaine or S(-)-bupivacaine. Ca(2+) uptake from the SR was not altered by the LA or by age.

CONCLUSIONS

Differences in the mechanisms for regulating intracellular SR Ca(2+) may contribute to the decreased susceptibility of young animals to cardiodepression induced by RS(±)-bupivacaine and S(-)-bupivacaine.

Plasma Levels of Lignocaine during Tumescent Local Anaesthesia in Children with Burns

The aim of the study was to assess the changes in plasma lignocaine concentrations over time when the tumescent solution is injected into subcutaneous tissue of children undergoing surgical treatment of burns. Sixteen consecutive children with burns were studied using a prospective study design. After induction of general anesthesia, tumescent lignocaine solution 0.1% with adrenaline in nine patients (adrenaline group) for the treatment of postburn sequelae, or without adrenaline in seven patients (no-adrenaline group) for the treatment of acute burns, was injected into the subcutaneous tissue of burned and donor areas. The maximum dose of lignocaine was 7 mg/kg. Blood samples were collected before the start of the injection as well as at 5, 10, 20, 30, 45, 60, 90 minutes and 2, 4, 8, 12, 24 hours after the infiltration was completed. The course of lignocaine plasma levels was chaotic in the adrenaline group and biphasic during the first hour in the no-adrenaline group. The maximum plasma concentration of lignocaine was 2.09 μg/ml in the adrenaline group and 1.98 μg/ml in the no-adrenaline group. No adverse reactions were noted. Tumescent injection in burned children resulted in lignocaine plasma concentrations that were always lower than the often quoted value of 5 μg/ml, considered to be the toxic plasma threshold in adults. These data lend support to the use of lignocaine using the tumescent technique in burned paediatric patients.

Ultrasound-guided proximal and distal sciatic nerve blocks in children

STUDY OBJECTIVE

To present the use of ultrasonography for the performance of proximal subgluteal and distal sciatic nerve blocks in children.

DESIGN

Prospective descriptive study.

SETTING

University hospital.

PATIENTS

45 ASA physical status I, II, and III patients, aged between 8 months and 16 years, scheduled for lower limb surgery.

INTERVENTIONS

During general anesthesia, proximal, subgluteal, and distal sciatic nerve blocks using ultrasonography were performed. If severe postoperative pain was expected, a catheter technique was used.

MEASUREMENTS

The injected amount of local anesthetic was noted. Based on the spread of local anesthetic, prediction for successful block was made. Complications, adverse effects, postoperative pain scores, and parent satisfaction scores were noted.

MAIN RESULTS

21 proximal sciatic nerve blocks (12 single-injection and 9 continuous blocks) and 35 distal sciatic nerve blocks (17 single-injection, 6 bilateral single-injection, 4 continuous, and one bilateral continuous block) were performed. A mean initial dose of 0.25 mL.kg(-1) of ropivacaine 0.375% was injected. A successful block was obtained in all children. Excellent postoperative pain relief was obtained. All parents were satisfied with the postoperative pain relief. No complications occurred.

CONCLUSION

Ultrasonography is useful in the identification of the sciatic nerve and it facilitates needle and catheter placement for proximal and distal nerve blocks in children.

Incisional continuous fascia iliaca block provides more effective pain relief and fewer side effects than opioids after pelvic osteotomy in children

BACKGROUND

Intravenous opioid therapy is frequently used for postoperative pain management in children after orthopedic surgery but causes side effects such as respiratory depression, vomiting, sedation, and urinary retention. To investigate whether a continuous incisional fascia iliaca compartment (FIC) block provides more effective postoperative pain relief with fewer side effects than IV morphine, we performed a prospective, double-blind, randomized study to compare both techniques.

METHODS

Thirty children (ASA physical status I-II) aged 3 mo to 6 yr undergoing a pelvic osteotomy were included in the study. The children were randomized for either morphine IV and placebo (saline) via a FIC catheter (Group M) or placebo (saline) IV and ropivacaine via a FIC catheter (Group R). All patients received general anesthesia using inhaled sevoflurane and IV fentanyl. Perioperatively, a FIC catheter was placed by the surgeon. All patients received either a bolus dose of morphine IV (Group M) or ropivacaine 0.75% via the FIC catheter (Group R) at the end of surgery. Postoperatively, Group M received morphine IV 20 microg x kg(-1) x h(-1) and Group R ropivacaine 0.2% 0.1 mL x kg(-1) x h(-1) via the FIC catheter. In both groups, saline was administered along the other route. All children were assessed for pain, sedation, time until first oral intake, and adverse effects for 48 h postoperatively. During this period, all children had a urinary catheter.

RESULTS

The study was completed by 28 children. In the anesthetic recovery room, children in Group M had significantly higher pain scores. These children were also significantly more sedated during the study period. The incidence of vomiting did not differ between the groups; however, children in Group R had first oral intake significantly earlier than Group M. A local retrospective study revealed an incidence of urinary retention of 4.7% in the ropivacaine-treated patients and 39% in the morphine-treated patients.

CONCLUSIONS

Continuous incisional FIC block provides excellent postoperative pain relief, less sedation, and better return of appetite than morphine IV after pelvic osteotomy in children.