Pharmacokinetics and analgesic effect of ropivacaine following ilioinguinal/iliohypogastric nerve block in children

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.

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.

Application of Ultrasound-Guided Ilioinguinal/Iliohypogastric Nerve Block in Pediatric Same-Day Surgery

The aim of this study was to evaluate the safety and efficacy of ultrasound-guided ilioinguinal/iliohypogastric nerve block (IINB) in pediatric patients undergoing same-day inguinal region surgery. Ninety patients aged 4-6 years, ASA levels I-II, were randomly divided into three groups: U, T, or C (n = 30 each). After basic anesthesia, patients in group U underwent ultrasound-guided IINB, those in group T underwent traditional Schulte-Steinberg IINB, and those in group C (controls) received intravenous anesthesia (ketamine-propofol) only. Patients who remained sensitive to intraoperative stimuli received additional intravenous doses of 1 mg/kg ketamine. Heart rate (HR), mean arterial pressure (MAP), and oxygen saturation (SPO2) were recorded upon entering the operating room (T0), at skin incision (T1), while pulling the hernia sac (T2), during skin closing (T3), and upon awakening (T4) at recovery. HR and MAP at T1, T2, and T4 were higher in group C than those in the other two groups, and recovery time in group C was significantly prolonged (P < 0.05). Group U required significantly lower quantities and frequency of ketamine injection, and pain scores in group U during awakening were lower than those in the other two groups (P < 0.05). Ultrasound-guided IINB provided an improved nerve block effect and postoperative analgesia, reduced the amount of local anesthetic required, facilitated more rapid postoperative recovery, and was a safe and effective method of anesthesia.

Bispectral index monitoring of propofol sedation during ultrasound guided nerve block for inguinal herniorraphy: A randomized prospective study

Background:

Patient's awareness can be reduced during ultrasound guided nerve block for inguinal herniorraphy with propofol sedation. The study was aimed to evaluate the clinical efficacy of direct visualization of anatomy of inguinal region by ultrasound and benefits of bispectral index (BIS) monitoring.

Materials and Methods:

After approval, 40 adult male consented patients of ASA grade I-III of 18-58 years with body mass index <25 were randomized into two groups of 20 patients each. A high frequency (8-13 MHz) linear transducer was used to perform the ilioinguinal and iliohypogastric nerves (ILHN and ILIN) block between the internal oblique and transversus abdominis muscles with 20 mL of 0.75% ropivacaine. The propofol infusion rate for sedation in patients of group I (non-BIS) was managed clinically and in patients of group II (BIS) was managed with BIS index of 65-75. Any surgical or anesthetic complications were recorded. The two groups were compared by evaluating the propofol consumption during surgery.

Results:

Ultrasonographic visualization of the ILHN and ILIN was possible in all patients and inguinal herniorraphy was performed uneventfully. The mean dose of propofol required for sedation was 5.45 mg/kg/h in patients of group I (non-BIS) while 4.92 mg/kg/h in patients of group II (BIS). The mean propofol consumption was not statistically significant (P = 0.12). All patients were hemodynamically stable and there was no respiratory depression during propofol sedation.

Conclusion:

Ultrasonography has facilitated the clinically effective nerve block for inguinal herniorraphy and BIS monitoring has ensured amnesia and faster emergence.

Patient-controlled regional analgesia is effective in children: a preliminary report

PURPOSE

To report a preliminary analysis of prospectively recorded data in 27 children in whom patient-controlled regional analgesia (PCRA) was used for postoperative pain control following lower limb surgery.

METHODS

Under general anesthesia, perineural catheters (popliteal and fascia iliaca compartment block) were inserted and infused with ropivacaine 0.2% (0.02 mL.kg(-1).hr(-1)). Additional demand doses were left to the child's discretion (0.1 mL.kg(-1)and a 30-min lockout interval).

RESULTS

The average total dose of ropivacaine administered was 4.9 +/- 2 mg.kg(-1)over 48 hr. Visual analogue scale and Children's Hospital of Eastern Ontario Pain Scale scores were always inferior to 5/10 and 6/13, respectively. Motor block was observed in two children and two children needed rescue analgesia.

CONCLUSIONS

Our preliminary observations indicate that PCRA in children provides satisfactory postoperative pain relief following lower limb surgery.

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.

Plasma ropivacaine concentrations after ultrasound-guided transversus abdominis plane block

BACKGROUND

The transversus abdominis plane block is a novel technique involving injection of local anaesthetic between the internal oblique and the transversus abdominis muscles of the abdominal wall. It is possible that injection of a large dose of local anaesthetic into a relatively vascular plane may result in toxic concentrations. One previously published study examined plasma lidocaine concentrations after transversus abdominus plane block and showed potentially toxic plasma concentrations. Although ropivacaine is most commonly used for this technique, plasma concentrations of ropivacaine after this block have not been reported previously.

METHODS

Adult female patients undergoing elective open gynaecological surgery received bilateral ultrasound-guided transverse abdominal plane blocks before surgical incision (3 mg kg(-1) of ropivacaine diluted to 40 ml). Venous blood was collected each 15 min for the first hour, each 30 min for the second hour, and then at 3, 4, 12, and 24 h post-block.

RESULTS

Twenty-eight patients were recruited. The mean (sd) peak total ropivacaine concentration occurred 30 min post-injection and was 2.54 (sd 0.75) µg ml(-1). The highest measured concentration was 4.00 µg ml(-1), also 30 min post-injection. Mean total concentrations remained above 2.20 µg ml(-1) for up to 90 min post-injection. The mean unbound peak venous concentration was 0.14 (0.05) µg ml(-1), and the peak was 0.25 µg ml(-1).

CONCLUSIONS

Transversus abdominus plane block using 3 mg kg(-1) of ropivacaine produces venous plasma concentrations that are potentially neurotoxic, although broadly consistent with plasma levels found after injection at other comparable sites.

Regional anesthesia for postoperative pain control in children: focus on continuous central and perineural infusions

Regional anesthesia is widely employed for postoperative pain control in both adults and children. Central or perineural approaches can be performed as a bolus injection or as a continuous infusion of local anesthetics. However, bolus injections, even with the addition of adjuvants, are inadequate for prolonged surgery and long-term pain control. Continuous infusion remains the technique of choice when there is a prolonged operation or intense postoperative pain. This article reviews the safety and efficacy of central and perineural continuous infusions for postoperative pain control in children. The literature confirms the very low rate of complications and adverse effects of regional anesthesia in children. However, clinicians need to be aware of the key points for performing a block and placing a catheter in children: good knowledge of anatomic and physiologic differences between adults and children is necessary; the use of newer local anesthetics, such as ropivacaine and levobupivacaine, increases the therapeutic window; and that it is mandatory to work with dedicated pediatric equipment. Through the use of new techniques such as nerve mapping and/or ultrasound the success of blocks can be improved and the risks reduced.

Ultrasound guidance for ilioinguinal/iliohypogastric nerve block: a pilot study

BACKGROUND

Ilioinguinal/iliohypogastric nerve block combined with general anaesthesia facilitates inguinal herniorrhaphy in an ambulatory setting by improving analgesia and reducing opioid requirements. Case reports in children indicate the possibility of colonic puncture and associated morbidity with blind ilioinguinal and iliohypogastric blockade.

AIMS

To investigate the feasibility of ultrasound guided ilioinguinal/iliohypogastric nerve block.

METHODS

Pilot study of four patients where ultrasound imaging was used to identify the ASIS, anterior abdominal muscle layers, the peritoneum and to guide local anaesthetic infiltration in patients undergoing inguinal hernia surgery and appendicectomy.

RESULTS

All patients had successful blocks, without complications. Mean visual analogue scores were 2/10 in the post anaesthesia care unit. Mean opioid consumption was 10 mg of intramuscular morphine in the first 24 h.

CONCLUSIONS

Ultrasound guidance for ilioinguinal and iliohypogastric nerve block in the inguinal region is both feasible and a promising technique.

[Perioperative analgesia with continuous peripheral nerve blocks in children]

Recently, regional anaesthesia in children has generated increasing interest. But single injection techniques have a limited duration of postoperative analgesia. Then, continuous peripheral nerve blocks have taken an important position in the anaesthetic arsenal, allowing an effective, safe and prolonged postoperative pain management. As adults, indications for continuous peripheral nerve blocks depend on the analysis of individual benefits/risks ratio. Main indications are intense postoperative pain surgical procedures, with or without postoperative rehabilitation, and complex regional pain syndrome. Contraindications to these procedures are rather similar to those in adults, plus parental and/or children refusal. Continuous peripheral nerve blocks are usually performed under general anaesthesia or sedation in children, and require appropriate equipment in order to decrease the risk of nerve injury. New techniques, such as transcutaneous nerve stimulation or ultrasound guidance, appeared to facilitate nerve and plexus approach identification in paediatric patients. Nevertheless, continuous peripheral nerve block may theoretically mask a compartment syndrome after trauma surgical procedures. Finally, ropivacaine appears to be the most appropriate drug for continuous peripheral nerve blocks in children, requiring low flow rates and concentrations of local anaesthetic. These techniques may facilitate early ambulation by an improved pain management or even postoperative analgesia at home with disposable pumps. One might infer from the current review that excellent pain relief coupled with a reduction of side effects would contribute to improve the quality of life and to decrease the frequency of disabling behavioural modifications in children, sometimes psychologically injured by hospital stay and postoperative pain.

A comparison of nerve stimulator guided paravertebral block and ilio-inguinal nerve block for analgesia after inguinal herniorrhaphy in children

The aim of this study was to compare the efficacy of nerve stimulator guided paravertebral block with ilio-inguinal nerve block in children undergoing inguinal herniorrhaphy. Eighty children were randomly allocated to receive either paravertebral block or ilio-inguinal nerve block. Each block was evaluated in terms of intra-operative haemodynamic stability, postoperative pain scores at rest, on movement and during activity, requirement for supplemental analgesia and parental satisfaction. Haemodynamic stability was maintained significantly better during sac traction in the paravertebral block group (p < 0.005). Pain scores and analgesic consumption were significantly lower in the paravertebral block group during the postoperative follow-up period (p < 0.05). Parental satisfaction (93%vs 69%) and surgeon satisfaction (93%vs 64%) were significantly higher in the paravertebral block group (p < 0.05). Paravertebral blockade improved and prolonged postoperative analgesia, and was associated with greater parental and surgeon satisfaction when compared to ilio-inguinal nerve block.

Anatomical bases of prolonged ilio-inguinal-hypogastric regional anesthesia

Although anesthesia and post-operative analgesia are associated with specific morbidity, regional anesthesia is not systematically given during groin hernia surgery. The goals of this work were to determine the anatomical bases of safe ilio-inguinal (II)-hypogastric anesthesia that can be prolonged into the post-operative period and to validate this technique on anatomical preparations and in clinical situations. We studied the courses of the ilio-hypogastric (IH) and II nerves in 33 halves of 20 embalmed adult cadavers. The intermediate portion of the IH and II nerves, located between the transverse and the internal oblique muscles, were found to be suitable for a simultaneous block with a single injection. We assessed the feasibility of injecting a percutaneous infiltration into this space by injecting a dye before dissection. In 75% of cases, we observed percutaneous coloring of the nerves, confirming that this site was suitable. To guide the infiltration, the points where the nerves passed through the transverse and the internal oblique muscles were located from the iliac crest and anterior and superior iliac spine, respectively. The nerve trunks were grouped for over 5 cm in a cell-fat layer running between these two deep muscles. It was possible to position a micro-catheter in this anatomical space to allow repeated injections. The results of this anatomical study were used to modify the technique so that it could be used to provide regional anesthesia in five patients operated on for hernia. Post-operative pain was very effectively controlled in four cases with no complications.

Efficacy and plasma levels of ropivacaine for children: controlled regional analgesia following lower limb surgery

BACKGROUND

Continuous regional analgesia (CRA) is considered a safe and efficacious technique for postoperative pain relief in children after lower limb surgery. We recently evaluated the feasibility of patient-controlled regional analgesia (PCRA) in a similar acute pain situation and we concluded that PCRA might be advantageous over CRA in terms of lower costs, risk of systemic toxicity while producing similarly adequate analgesia. We therefore prospectively compared both techniques in the paediatric population.

METHODS

In total, 30 children undergoing lower limb orthopaedic surgery were randomized to receive PCRA or CRA with ropivacaine 0.2%. Visual analogue scale scores, rescue analgesia, overall satisfaction, motor blockade and plasma ropivacaine concentrations were recorded for 48 h.

RESULTS

Adequate analgesia was achieved with both techniques. No significant difference was noted for rescue analgesia, overall satisfaction and motor blockade. In contrast, children in the PCRA group received significantly less local anaesthetics than those in the CRA group. In addition, total plasma concentrations of ropivacaine were significantly reduced in the PCRA group as compared with the CRA group during the 48 h postoperative period.

CONCLUSIONS

Both techniques are efficacious and satisfactory. However, PCRA with ropivacaine 0.2% can provide adequate postoperative analgesia for paediatric orthopaedic procedures with smaller doses of ropivacaine than CRA.

Recent pharmacological advances in paediatric analgesics

Growth and development are two linked processes that distinguish children from adults. The use of size as the primary covariate during pharmacokinetic (PK) analyses allows exploration of the effects of age. Allometric scaling models have assisted understanding of the developmental clearance changes in common analgesic drugs such as paracetamol, morphine, tramadol and local anaesthetics agents. Single nucleotide polymorphisms (pharmacogenomics [PG]) and their impact on hepatic drug metabolism for opioids, tramadol, non-steroidal anti-inflammatory drugs (NSAIDs) and drug receptor responses are increasingly reported. Altered chemical structure or formulations of common analgesics alter pharmacodynamic (PD) effects enhancing safety and efficacy for NSAIDs by stereoselectivity and the addition of nitric oxide, for intravenous paracetamol by formulation and structural difference from propacetamol and for local anaesthetics through stereoselectivity. This article focuses upon recent data for analgesics used in paediatric pain management including paracetamol, NSAIDs, morphine, tramadol, amide local anaesthetics and ketamine. It centres on PK and clinical studies in neonates, infants and children. PG studies are acknowledged as potentially allowing individual drug therapy tailoring through a decrease in between-patient population variability, although the impact of PG in the very young is less certain. There are few data describing age-related PD changes in children despite recognition that the number, affinity and type of receptors or the availability of natural ligands changes with age.

Ultrasonographic-Guided Ilioinguinal/Iliohypogastric Nerve Block in Pediatric Anesthesia: What is the Optimal Volume?

Recently, our study group demonstrated the usefulness of ultrasonographic guidance in ilioinguinal/iliohypogastric nerve blocks in children. As a consequence, we designed a follow-up study to evaluate the optimal volume of local anesthetic for this regional anesthetic technique. Using a modified step-up-step-down approach, with 10 children in each study group, a starting dose of 0.2 mL/kg of 0.25% levobupivacaine was administered to perform an ilioinguinal/iliohypogastric nerve block under ultrasonographic guidance. After each group of 10 patients, the results were analyzed, and if all blocks were successful, the volume of local anesthetic was decreased by 50%, and a further 10 patients were enrolled into the study. Failure to achieve a 100% success rate within a group subjected patients to an automatic increase of half the previous volume reduction to be used in the subsequent group. Using 0.2 and 0.1 mL/kg of 0.25% levobupivacaine, the success rate was 100%. With a volume of 0.05 mL/kg of 0.25% levobupivacaine, 4 of 10 children received additional analgesia because of an inadequate block. Therefore, according to the protocol, the amount was increased to 0.075 mL/kg of 0.25% levobupivacaine, where the success rate was again 100%. We conclude that ultrasonographic guidance for ilioinguinal/iliohypogastric nerve blocks in children allowed a reduction of the volume of local anesthetic to 0.075 mL/kg.

Lich-Gregoir Reimplantation Causes Less Discomfort than Politano-Leadbetter Technique: Results of a Prospective, Randomized, Pain Scale-Oriented Study in a Pediatric Population

OBJECTIVE

There is a consensus that transvesical reimplantation is more appropriate in cases of bilateral vesicoureteral reflex (VUR). In contrast to that it is not yet clear which approach should be used in unilateral VUR. This prospective, randomized trial compared the benefits and drawbacks of the intravesical and extravesical techniques in terms of operative comorbidity.

METHODS

Forty-four children (29 girls, 15 boys, mean age, 67.23 mo) with unilateral VUR were assigned to two groups: 22 patients underwent Lich-Gregoir reimplantation and 22 underwent the intravesical Politano-Leadbetter technique. Follow-up evaluation included renal ultrasonography and voiding cystourethrography (VCUG) 6 mo postoperatively. The groups were compared for operative time, duration of hematuria, upper tract dilation, discomfort and pain, analgesic requirements, voiding dysfunction, and reflux persistency.

RESULTS

No child had persistent VUR. Contralateral degrees II VUR was noted in five patients without significant difference regarding the treatment (p = 0.345). It was transient in all cases. Operative time was shorter using the extravesical technique (66.73 min versus 79.28 min; p < 0.0001). Gross hematuria occurred only after intravesical reimplantation lasting 4.19 d (p < 0.00001). The objective pain score was worse after intravesical surgery (p = 0.002). Analgesic requirements were higher after the Politano reimplantation (p = 0.039).

CONCLUSIONS

Both unilateral extravesical and intravesical reimplantation definitively correct VUR. The mean operative time was significantly shorter using the Lich-Gregoir technique, which underlines its simplicity; additionally, gross hematuria can be avoided. Postoperative pain and bladder spasms were reduced using the extravesical approach. Consequently, it represents an effective surgical technique to correct reflux while operative morbidity is low. Therefore it is the method of choice in cases of unilateral VUR requiring correction.

Regional Anesthesia in Children

The future of regional anesthesia in children is to continue to use current techniques, but also to search for ways to make them easier to employ. The potential development of safe local anesthetic agents with much longer durations, will serve to facilitate improvements in the techniques and styles of practice. The advances in minimally invasive surgical techniques do not mean that regional techniques will not be necessary, but will result in an adaptation of techniques. Peripheral nerve blockade and local wound infiltration can still be used and in some instances, may be very appropriate.

Continuous peripheral nerve blocks in children

In recent years, regional anaesthesia in children has generated increasing interest. Continuous peripheral nerve blocks have an important role in the anaesthetic arsenal, allowing effective, safe and prolonged postoperative pain management. Indications for continuous peripheral nerve blocks depend on benefits/risks analysis of each technique for each patient. The indications include surgery associated with intense postoperative pain, surgery requiring painful physical therapy, and complex regional pain syndrome. Continuous peripheral nerve blocks are usually performed under general anaesthesia or sedation, and require appropriate equipment in order to decrease the risk of nerve injury. New techniques, such as transcutaneous stimulation or ultrasound guidance, appear to facilitate nerve and plexus identification in paediatric patients. Nevertheless, continuous peripheral nerve block may mask compartment syndrome in certain surgical procedure or trauma. Finally, ropivacaine appears to be the best local anaesthetic for continuous peripheral nerve blocks in children, requiring low flow rate with low concentration of the local anaesthetic.

Evaluation of genitofemoral nerve block, in addition to ilioinguinal and iliohypogastric nerve block, during inguinal hernia repair in children

BACKGROUND

Ilioinguinal and iliohypogastric (IG-IH) nerve block has been widely used in children undergoing inguinal hernia repair. This technique may provide insufficient analgesia for intraoperative management as the inguinal region may receive sensory innervation from genitofemoral nerve. We proposed that addition of a genitofemoral nerve block might improve the quality of analgesia.

METHODS

Ninety-eight children undergoing inguinal hernia repair were assigned randomly to receive either IG-IH nerve block (Group I) or IG-IH and genitofemoral nerve blocks (Group II). Systolic arterial pressure (SAP) and heart rate (HR) were recorded before surgery (control), after skin incision, at sac traction and at the end of surgery. Postoperative analgesic requirements and incidence of complications were recorded until discharge.

RESULTS

At sac traction, SAP and HR were significantly higher in Group I (P<0.05), and the incidence of episodes of increased HR was also significantly higher in Group II (29 vs 12%, respectively, P<0.05). There were no significant differences in SAP and HR at other time points, postoperative analgesic requirements or incidence of complications between the groups.

CONCLUSIONS

The benefit of the additional genitofemoral nerve block to IG-IH nerve block was limited only to the time of sac traction without any postoperative effect. This suggests there is little clinical benefit in the addition of a genitofemoral nerve block.

Comparison of ropivacaine with bupivacaine and lidocaine for ilioinguinal block after ambulatory inguinal hernia repair in children

BACKGROUND

We have compared ropivacaine with bupivacaine and lidocaine for ilioinguinal block in thirty children undergoing ambulatory inguinal hernia repair.

METHODS

Patients were assigned randomly to receive 0.5 ml.kg(-1) of 0.2% ropivacaine (Group R, n = 10), 0.25% bupivacaine (Group B, n = 10) or 1% lidocaine (Group L, n = 10). The patients' parents, who were not informed of the type of local anaesthetic employed, evaluated the postoperative pain at 2 h and 6 h after operation using the Wong-Baker FACES Pain Rating Scale.

RESULTS

There was a significant difference in the face scale score between Group R and Group L, and Group B and Group L. There was no difference in the face scale score between Group R and Group B. There were no complications or clinical evidence of local anaesthetic toxicity.

CONCLUSIONS

We have confirmed that bupivacaine and ropivacaine are more effective than lidocaine in the prevention of postoperative pain after children's inguinal hernia repair. We suggest that ropivacaine 0.2% is an alternative to bupivacaine 0.25% for ilioinguinal block in ambulatory paediatric surgery.

High plasma ropivacaine concentrations after fascia iliaca compartment block in children

BACKGROUND

The pharmacokinetic profile of local anaesthetics is influenced by the mode of administration. We sought to compare the pharmacokinetics of two doses of ropivacaine after fascia iliaca compartment (FIC) block in children.

METHODS

In this prospective, double-blind study, children received an FIC block as a part of their anaesthetic management during elective orthopaedic surgery on the thigh. They were randomized to receive ropivacaine 0.7 ml x kg(-1) using either a 0.375% or 0.5% solution. Venous blood samples were drawn up to 6 h after injection. Plasma concentrations of ropivacaine were measured by gas-liquid chromatography.

RESULTS

Six children (10.2 (range 5-15) yr, 35.6 (sd 10) kg were included. FIC block provided satisfactory peroperative pain relief. No signs of toxicity were observed, but high maximal plasma concentrations (C(max) 4.33-5.6 microg ml(-1)), were observed for three of four patients in the ropivacaine 0.5% group. The two patients in the 0.375% group showed values within the safe range (C(max) 0.66 and 0.98 microg ml(-1) respectively). Even though no toxic effects were observed, these results led us to discontinue the study.

CONCLUSIONS

The administration of ropivacaine 3.5 mg x kg(-1) can be associated with sustained high plasma concentrations of ropivacaine, outside the tolerable range. In view of these results, we recommend the use of lower ropivacaine dosage during FIC block in children.

Pharmacokinetics of Local Anaesthetics in Infants and Children

Amide local anaesthetics used for regional anaesthesia in paediatric patients are potent sodium channel blockers with marked stereospecificity, which consistently influences their action, especially their toxic action on the heart. At toxic concentrations, they induce severe arrhythmias with the potential for cardiac arrest. These agents are all bound to serum proteins, mainly to alpha(1)-acid glycoprotein (AAG), but also to human serum albumin. Protein binding ranges from 65% (lidocaine) to more than 95% (bupivacaine, ropivacaine). Because AAG is a major acute phase protein, its concentration rapidly increases when inflammatory processes develop, particularly during the postoperative period. Neonates and infants have a lower AAG concentration in serum as compared with adults; therefore, their free fraction of local anaesthetics is increased accordingly. This has important clinical implications since, at least at steady state, the toxic effects of local anaesthetics are directly related to the free (unbound) drug concentration. After injection into the epidural space, absorption into the bloodstream follows a biphasic process. The buffering properties of the epidural space are important and prevent a rapid rise in concentration. In infants and children, the epidural space seems to protect patients in a similar manner. Moreover, it has been observed that the peak plasma concentration (C(max)) of ropivacaine is delayed in infants and children when compared with adults. The time to C(max) decreases from 90-120 minutes in infants aged less than 6 months to 30 minutes in children aged more than 8 years. This delay in C(max) may also be related to the lower clearance observed in younger patients. Local anaesthetics are metabolised by cytochrome P450 (CYP). The main CYP isoforms involved are CYP3A4 for lidocaine and bupivacaine and CYP1A2 for ropivacaine. CYP3A4 is not mature at birth but is partly replaced by CYP3A7. The intrinsic clearance of bupivacaine is only one-third of that in adults at 1 month of age, and two-thirds at 6 months. CYP1A2 is not fully mature before the age of 3 years. Indeed, the clearance of ropivacaine does not reach its maximum before the age of 5 years. However, at birth this clearance is not as low as expected, and ropivacaine may be used even in younger patients.

Ropivacaine in infants and children

PURPOSE OF REVIEW

Ropivacaine is considered less toxic than bupivacaine. In addition, at the low concentrations used for providing postoperative analgesia, ropivacaine seems to produce less motor blockade than bupivacaine. These two properties are of particular interest in paediatric practice.

RECENT FINDINGS

In paediatric practice regional anaesthesia is usually performed under general anaesthesia, and postoperative analgesia was until recently the major concern for most practitioners. The question now is: what is the right concentration to provide adequate intraoperative anaesthesia when ropivacaine is used in combination with volatile anaesthetic agents? The low concentration of ropivacaine used for postoperative analgesia seems to provide adequate intraoperative anaesthesia when general anaesthesia with a 0.5 minimum concentration of volatile anaesthetic is used in combination. However, potential toxicity is still the subject of debate because ropivacaine clearance is low in infancy and early childhood. Ropivacaine has a longer absorption process than bupivacaine, which leads to a lower maximum peak concentration with ropivacaine than with bupivacaine either after central or peripheral blocks, thus increasing the safety of the drug. The addition of adjuvant drugs also permits lower concentrations of ropivacaine, while providing excellent analgesia. The addition of adrenaline at very low concentrations has recently been found to increase the quality of epidural analgesia.

SUMMARY

Ropivacaine is now the reference drug for regional anaesthesia in paediatric patients, mainly because it is considered less toxic than bupivacaine and provides excellent postoperative analgesia even when used at low concentrations.

Benefit and risks of local anesthetics in infants and children

Regional anesthesia has become a routine part of the practice of anesthesiology in infants and children. Local anesthetic toxicity is extremely rare in infants and children; however, seizures, dysrhythmias, cardiovascular collapse, and transient neuropathic symptoms have been reported. Infants and children may be at increased risk from local anesthetics compared with adults. Larger volumes of local anesthetics are used for epidural anesthesia in infants and children than in adults. Metabolism and elimination of local anesthetics can be delayed in neonates, who also have decreased plasma concentrations of alpha(1)-acid glycoprotein, leading to increased concentrations of unbound bupivacaine. Most regional anesthetic procedures in infants and children are performed with the patient heavily sedated or anesthetized; because of this, and because a test dose is not a particularly sensitive marker of intravenous injection in the anesthetized patient, detection of intravascular local anesthetic injection is extremely difficult. The same local anesthetics used in adult anesthetic practice are also used in infants and children. Because of its extremely short duration of action, chloroprocaine has been used primarily for continuous epidural techniques in infants and children. The use of tetracaine has generally been limited to spinal and topical anesthesia. Lidocaine (lignocaine) has been used extensively in infants and children for topical, regional, plexus, epidural and spinal anesthesia. The association between prilocaine and methemoglobinemia has generally restricted prilocaine use in infants and children to the eutectic mixture of local anesthetics (EMLA). Because of its greater degree of motor block compared with other long-acting local anesthetics, etidocaine has generally been limited to plexus blocks in infants and children. Mepivacaine has been used for both plexus and epidural anesthesia in infants and children. Because postoperative analgesia is often the primary justification for regional anesthesia in infants and children, bupivacaine, a long-acting local anesthetic, is the most commonly reported local anesthetic for pediatric regional anesthesia. Given the lower toxic threshold of bupivacaine compared with other local anesthetics, the risk-benefit ratio of bupivacaine may be greater than that of other local anesthetics. Two new enantiomerically pure local anesthetics, ropivacaine and levobupivacaine, offer clinical profiles comparable to that of bupivacaine but without its lower toxic threshold. The extreme rarity of major toxicity from local anesthetics suggests that widespread replacement of bupivacaine with ropivacaine or levobupivacaine is probably not necessary. However, there are clinical situations, including prolonged local anesthetic infusions, use in neonates, impaired hepatic metabolic function, and anesthetic techniques requiring a large mass of local anesthetic, where replacement of bupivacaine with ropivacaine, levobupivacaine or (for continuous techniques) chloroprocaine appears prudent.

Voiding cystourethrography using the suprapubic versus transurethral route in infants and children: results of a prospective pain scale oriented study

PURPOSE

We determined the advantages and disadvantages of different types of contrast medium injection into the bladder for imaging children during evaluation for urinary tract infection in regard to child behavior and distress during urethral catheterization or suprapubic puncture.

MATERIALS AND METHODS

From December 2000 to September 2001 we prospectively compared transurethral catheter and suprapubic voiding cystourethrography in children with a history of urinary tract infection. A total of 65 children with a mean age of 33.8 months were entered into the study, of whom 32 underwent transurethral catheterization and 33 underwent suprapubic puncture with topical anesthesia. Each child was evaluated, particularly in regard to discomfort and pain using an objective pain score that measures stress and pain during a medical procedure.

RESULTS

Objective pain score recording showed a mean pain score plus or minus SD of 4.25 +/- 1.3 in the transurethral catheterization and 3.03 +/- 1.21 in the suprapubic puncture groups. Correlation studies of age in the 2 groups also showed a significant impact of age on the objective pain score. In the transurethral group the score increased with age (p <0.001), whereas in the suprapubic group it decreased with age (p <0.001).

CONCLUSIONS

The current study shows that the suprapubic puncture technique with topical anesthesia was well tolerated and associated with a low pain score independent of patient age. Transurethral catheterization was also tolerated but it was associated with a low pain score only in the younger age group. Thus, we recommend that voiding cystourethrography in children older than 24 months should be done via the suprapubic route.