Adjunct analgesic drugs to local anaesthetics for neuroaxial blocks in children

Postoperative Pain Management in children: guidance from the Pain Committee of the European Society for Paediatric Anaesthesiology (ESPA Pain Management Ladder Initiative) Part II

The ESPA Pain Management Ladder Initiative is a clinical practice advisory based upon expert consensus supported by the current literature to help ensure a basic standard of perioperative pain management for all children. In 2018 the perioperative pain management of six common pediatric surgical procedures was summarised. The current Pain Management Ladder recommendations focus on five more complex pediatric surgical procedures and suggest basic, intermediate, and advanced pain management methods. The aim of this paper is to encourage best possible pain management practice and to support institutions to create their own pain management concepts according to their financial and human resources due to the diversity of clinical settings in Europe. Furthermore, the authors underline that these recommendations are intended for inpatients only.

The effect of combined pudendal nerve and spermatic cord block or caudal epidural block on postoperative analgesia after posterior urethroplasty: a randomized trial

BACKGROUND

Postoperative pain management remains a significant challenge for patients undergoing posterior urethroplasty (PU). In a previous study, we proposed a novel technique of combined pudendal nerve (PN) and spermatic cord (SC) block to manage pain after PU. The present trial was conducted to test the hypothesis that this technique is effective for pain control after PU and provides longer-lasting analgesia than caudal epidural block (CB).

METHODS

Sixty patients undergoing PU were randomized into two groups: Group NB received combined PN and SC block, and Group CB received CB. General anesthesia with a laryngeal mask was performed. The primary outcome was the postoperative analgesic duration, and the secondary outcomes included the Numeric Rating Scale (NRS) scores for pain and the number of patients with different motor scores of the lower limb at 3, 6, 12, and 24 h postoperatively.

RESULTS

Two patients in Group CB were withdrawn due to block failure. The postoperative analgesic duration was statistically longer in Group NB compared with Group CB (mean difference [95% confidence interval], 115.78 min [17.80, 213.75]; P = 0.021). The NRS scores for pain at 12 and 24 h after surgery were statistically lower in Group NB compared with Group CB. Group NB had statistically more patients with motor score 0 at 3 h postoperatively than Group CB.

CONCLUSIONS

PN combined with SC block is an effective technique for postoperative analgesia in PU. This technique can achieve a longer duration of analgesia and lower pain scores, especially 12 h after surgery, than a CB.

TRIAL REGISTRATION

This study was registered in the Chinese Clinical Trial Register (registration no. ChiCTR2100042971, registration date on 2/2/2021).

Short-acting versus long-acting opioids for pediatric postoperative pain management

INTRODUCTION

Opioids are potent analgesics commonly used to manage children's moderate to severe perioperative pain in children. A wide range of short and long-acting opioids are used to treat surgical pain and will be reviewed in this article.

AREAS COVERED

Both short- and long-acting opioids contain unique therapeutic benefits and adverse effects; however, due to the side effect profile and safety concerns, lack of familiarity, and evidence with long-acting opioids to treat surgical pain, shorter-acting opioids have traditionally been used in children. Almost all opioids work by binding to the mu receptor. Methadone, a long-acting opioid, is an exception because it also has beneficial N-methyl-D-aspartate antagonist properties. Clinically methadone's properties could translate to improved analgesic outcomes, reduced risk of adverse events, less risk for acute hyperalgesia, tolerance and abuse potential, faster recovery, and reduced risk for chronic persistent surgical pain. This review article summarizes and compares the evidence of commonly used short and long-acting opioids for perioperative pain control in the pediatric population.

EXPERT OPINION

Individualized methadone therapy using pharmacogenomics has the potential to transform opioid use in pain management by improving patient safety and analgesic outcomes, thereby addressing the gaps in current standardized ERAS protocols.

Advantages of ketamine in pediatric anesthesia

Although ketamine is primarily used for induction and maintenance of general anesthesia, it also presents sedative, amnestic, anesthetics, analgesic, antihyperalgesia, neuroprotective, anti-inflammatory, immunomodulant, and antidepressant effects. Its unique pharmacodynamics and pharmacokinetic properties allow the use of ketamine in various clinical settings including sedation, ambulatory anesthesia, and intensive care practices. It has also adopted to manage acute and chronic pain management. Clinically, ketamine produces dissociative sedation, analgesia, and amnesia while maintaining laryngeal reflexes, with respiratory and cardiovascular stability. Notably, it does not cause respiratory depression, maintaining both the hypercapnic reflex and the residual functional capacity with a moderate bronchodilation effect. In the pediatric population, ketamine can be administered through practically all routes, making it an advantageous drug for the sedation required setting such as placement of difficult vascular access and in uncooperative and oppositional children. Consequently, ketamine is indicated in prehospital induction of anesthesia, induction of anesthesia in potentially hemodynamic unstable patients, and in patients at risk of bronchospasm. Even more, ketamine does not increase intracranial pressure, and it can be safely used also in patients with traumatic brain injuries. This article is aimed to provide a brief and practical summary of the role of ketamine in the pediatric field.

Review of clinical evidence of caudal block for postoperative analgesia in children with ketamine added local anesthetics

Background

Adding ketamine to local anesthetics used for caudal block in children is an emerging clinical practice. This review aims to resolve controversies related to this adjuvant for a caudal block in children who underwent sub-umbilical surgeries.

Methods

Between January 2010 and November 2021, PubMed, Cochrane Review, and Google Scholar were searched for a caudal block with ketamine added local anesthetics for children. After screening for eligibility and removing duplicates, 38,187 articles were found, 13 reviewed.

Discussion

Despite adding ketamine to local anesthetics used for a caudal block, it is a recent technique practiced worldwide. Ketamine showed equi-efficacious as other adjuvants used for the caudal block to control postoperative pain in children.

Conclusion

Ketamine with a 0.5 mg/kg dose is safe and effective to manage postoperative children's pain when used as an adjuvant to local anesthetics used for caudal block.

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Caudal additives prolong the length of analgesia than local anesthetics alone

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Ketamine is an alternative to be added for local anesthetics in a caudal block for children

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Ketamine in caudal block prolongs analgesia and reduces opioid intake.

Biased, Bitopic, Opioid-Adrenergic Tethered Compounds May Improve Specificity, Lower Dosage and Enhance Agonist or Antagonist Function with Reduced Risk of Tolerance and Addiction

This paper proposes the design of combination opioid-adrenergic tethered compounds to enhance efficacy and specificity, lower dosage, increase duration of activity, decrease side effects, and reduce risk of developing tolerance and/or addiction. Combinations of adrenergic and opioid drugs are sometimes used to improve analgesia, decrease opioid doses required to achieve analgesia, and to prolong the duration of analgesia. Recent mechanistic research suggests that these enhanced functions result from an allosteric adrenergic binding site on opioid receptors and, conversely, an allosteric opioid binding site on adrenergic receptors. Dual occupancy of the receptors maintains the receptors in their high affinity, most active states; drops the concentration of ligand required for full activity; and prevents downregulation and internalization of the receptors, thus inhibiting tolerance to the drugs. Activation of both opioid and adrenergic receptors also enhances heterodimerization of the receptors, additionally improving each drug's efficacy. Tethering adrenergic drugs to opioids could produce new drug candidates with highly desirable features. Constraints-such as the locations of the opioid binding sites on adrenergic receptors and adrenergic binding sites on opioid receptors, length of tethers that must govern the design of such novel compounds, and types of tethers-are described and examples of possible structures provided.

Clonidine as an Additive to Local Anesthetics in Caudal Block for Postoperative Analgesia in Pediatric Surgery: A Systematic Review and Meta-Analysis

Background: Clonidine is an anesthetic with favorable efficacy and safety profiles for caudal epidural block, but comparisons with other adjuvants need to be confirmed in pediatric patients. Aim: To investigate the effects of clonidine as an adjuvant in caudal epidural block to improve the intraoperative and postoperative analgesia in pediatric surgery. Methods: PubMed, Embase, and the Cochrane Library were searched for available papers published up to February 2021. The outcomes were pain score, duration of analgesia, complications, and number of analgesic requirements. The meta-analysis was performed using random-effects models. Results: Fifteen randomized controlled trials (RCTs) were included. There were no differences between clonidine and the control drug regarding the duration of analgesia (SMD = -0.71, 95%CI: -1.64, 0.23; I ² = 95.5%, P_{heterogeneity} < 0.001), pain score (SMD = 0.35, 95%CI: -0.28, 0.98; I ² = 80.8%, P_{heterogeneity} < 0.001), and requirement for additional analgesia (OR = 8.77, 95%CI: 0.70, 110.58, I ² = 81.9%, P_{heterogeneity} = 0.004), but using clonidine resulted in fewer complications than the control drugs (OR = 0.33, 95%CI: 0.20, 0.54, I ² = 21.8%, P_{heterogeneity} = 0.217). The sensitivity analysis showed that the results were robust. A publication bias was observed. Conclusion: Clonidine has the same efficacy as the other adjuvants for caudal epidural block for pediatric surgery but fewer complications. These results support clonidine as an adjuvant to local anesthetic, but additional studies should be conducted.

Clonidine and Morphine as Adjuvants for Caudal Anaesthesia in Children: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Objective

The aim of this systematic review and meta-analysis is to compare the outcomes of morphine vs. clonidine use as adjuvants in caudal anaesthesia. We are specifically focused on analgesic and side effect profiles.

Methods

We searched databases and trial registration sites and include here randomised controlled trials that compare the analgesic effects of caudal clonidine vs. morphine as adjuvants on postoperative pain. The risk ratio for evaluating pain scores, the need for rescue analgesia and all adverse effects were assessed. The i2 statistic was used to assess heterogeneity. We also assessed risk of bias with Cochrane’s Collaboration tool. The quality of evidence was assessed with Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

Results

Four randomised controlled trials (including 166 patients) that evaluated the use of clonidine vs. morphine as adjuvants in caudal block were included in this systematic review and meta-analysis. The pooled estimate for postoperative analgesia revealed no statistically significant differences between the clonidine group compared to morphine group (MD=2.90; 95% CI 4.05 to 9.85; i2 93%). Significantly less postoperative nausea and vomiting were reported among the patients that received clonidine vs. those that were treated with morphine (RR 0.57, 95% CI −0.36 to −0.90, i2 26%). There were no statistically significant differences between the two groups in assessments that included urinary retention, pain scores or need for rescue analgesia at 24 hours.

Conclusion

Clonidine is just as effective as morphine when used an adjuvant to local anaesthetic for caudal block, and has a more desirable side effect profile, particularly with respect to postoperative nausea and vomiting.

Comparison of quadratus lumborum block and caudal block for postoperative analgesia in pediatric patients undergoing inguinal hernia repair and orchiopexy surgeries: a randomized controlled trial

Background and objectives

Caudal epidural anesthesia is a widely used popular technique for postoperative analgesia but it has potential side effects and duration of analgesia is short. Quadratus lumborum block (QLB) was found to be an effective method for postoperative analgesia in lower abdominal surgeries. In this double-blind prospective randomized trial, we aimed to compare the postoperative analgesic efficacies of QLB and the caudal block in pediatric patients undergoing inguinal hernia repair and orchiopexy surgeries under general anesthesia.

Materials and methods

After approval was obtained from the ethics committee, in this prospective randomized double-blind trial, 53 patients under general anesthesia undergoing inguinal hernia repair and orchiopexy surgeries randomly received caudal block or QLB. Demographic data, postoperative analgesic requirement, Face, Legs, Activity, Cry, and Consolability (FLACC) scores at 30 min, 1, 2, 4, 6, 12 and 24 hours, parent satisfaction scores and complications were recorded.

Results

The study included 52 patients, after excluding one patient because of a failed caudal block. There were no significant differences between the groups based on demographic data (p>0.05). The number of patients who required analgesics in the first 24 hours was significantly lower in QLB group (p=0.001). Postoperative 4, 6, 12 hours FLACC scores were significantly lower in the QLB group (p<0.001, p=0.001 and p<0.001, respectively). Parent satisfaction scores were higher in the QLB group (p=0.014).

Conclusion

According to the results of this study, QLB can provide much more effective analgesia than caudal block without adjuvants in multimodal analgesia management of children undergoing inguinal hernia repair and orchiopexy surgeries.

Trial registration number

NCT03294291.

Capsazepine prolongation of the duration of lidocaine block of sensory transmission in mice may be mediated by modulation of HCN channel currents

Background and objectives

Hyperpolarization-activation cyclic nucleotide-gated (HCN) channels contribute to the effects of lidocaine. Capsazepine (CPZ), a competitive inhibitor of capsaicin of transient receptor potential vanilloid-1 channel, has also been found to inhibit HCN channel currents (I _h). This study was designed to investigate whether CPZ could prolong durations of lidocaine in regional anesthesia.

Methods

Mouse HCN1 and HCN2 channels were expressed in human embryonic kidney 293 (HEK 293) cells. The effect of CPZ on I _h was measured by whole-cell patch-clamping recording. Sciatic nerve block model in mice was used for the study in vivo. The mice were randomly divided into seven groups, respectively, receiving lidocaine, CPZ, ZD7288 (HCN channel blocker), CPZ + lidocaine, ZD7288 + lidocaine, ZD7288 + CPZ + lidocaine, forskolin (an activator of adenylyl cyclase) + CPZ + lidocaine. Regional anesthetic durations of lidocaine were determined. Voltage-gated sodium channel currents (I _Na) and I _h were recorded in dorsal root ganglion neurons of mice. The effects of CPZ on I _Na and I _h with or without Cyclic adenosine monophosphate (cAMP) were assessed. Isolated mice sciatic nerve was prepared to evaluate the effect of CPZ on the compound action potentials (CAP).

Results

Capsazepine non-selectively inhibited transfected mHCN1 and mHCN2 channel currents in HEK 293 cells. In sciatic nerve block in vivo, compared to lidocaine alone, adding CPZ extended the durations of lidocaine for noxious sensory block (35.1 ± 3.3 vs. 20.3 ± 1.7 min), tactile sensory block (25.5 ± 4.4 vs. 20.0 ± 3.7 min), thermal sensory block (39.6 ± 6.6 vs. 26.8 ± 5.5 min), and motor function block (28.6 ± 4.1 vs. 20.9 ± 4.2 min). Duration of thermal sensory block was longer in CPZ + lidocaine group than that of ZD7288 + lidocaine group (39.6 ± 6.6 vs. 33.4 ± 4.5 min). Forskolin reversed the prolongation by CPZ on lidocaine durations. CPZ or ZD7288 alone did not produce typical regional anesthetic effects. Increased intracellular concentration of cAMP reversed the inhibition of CPZ on I _h. Although CPZ alone inhibited I _Na at the concentration more than 30 μM, it did not inhibit the CAP amplitudes in isolated sciatic nerves. CPZ dose-dependently enhanced the inhibitory effect of 1% lidocaine on the CAP amplitudes.

Conclusions

Capsazepine may prolong durations of lidocaine in peripheral nerve block by modulation of HCN channel currents.

Effects of intravenous dexmedetomidine infusion on local anaesthetic block: A spinal anaesthesia clinical model in dogs undergoing hind limb surgery

The aim of this randomised, prospective clinical trial was to determine how the administration of a low dose of dexmedetomidine (DEX) by IV constant rate infusion, modified the duration of the nerve block in dogs undergoing spinal anaesthesia (SA) in a clinical setting. Forty-four dogs undergoing hind limb orthopaedic surgery in a day-surgery regime, maintained under anaesthesia with isoflurane plus SA, were randomly assigned to receive 1 μg/kg/h (IV) of DEX (group D) or not (group C). Spinal anaesthesia was performed with a hyperbaric solution of bupivacaine and morphine at the L_5-6 interspace. Every mean arterial pressure (MAP) increase by 30% above the pre-skin incision value was considered an intraoperative analgesic failure and treated with a bolus of fentanyl as intraoperative rescue analgesia (iRA). Time free from iRA was analysed with a Kaplan-Maier survival curve. The ability to walk at 5 h from SA and the event of bradycardia (HR lower 60 beat per min) and hypotension (MAP value lower 60 mmHg) were recorded. The mean times at which iRA was required were 77.4 (3.2) in group C and 112.2 (8.6) in group D (Logrank test P = 0.038). In groups C and D hypotension incidence was 11/17 (65%) and 2/22 (9%), (P = 0.0004) and bradycardia 3/17 (18%) and 6/22 (27%) (P = 0.704), respectively. The ability to walk 5 h after SA was 14/14 (100%) and 13/14 (93%) in groups C and D, respectively. DEX infusion significantly prolonged the duration of the nociceptive nervous block without prolonging the motor block or increasing the bradycardia events.

Caudal epidural blocks in paediatric patients: a review and practical considerations

Caudal epidural blockade in children is one of the most widely administered techniques of regional anaesthesia. Recent clinical studies have answered major pharmacodynamic and pharmacokinetic questions, thus providing the scientific background for safe and effective blocks in daily clinical practice and demonstrating that patient selection can be expanded to range from extreme preterm births up to 50 kg of body weight. This narrative review discusses the main findings in the current literature with regard to patient selection (sub-umbilical vs mid-abdominal indications, contraindications, low-risk patients with spinal anomalies); anatomical considerations (access problems, age and body positioning, palpation for needle insertion); technical considerations (verification of needle position by ultrasound vs landmarks vs 'whoosh' or 'swoosh' testing); training and equipment requirements (learning curve, needle types, risk of tissue spreading); complications and safety (paediatric regional anaesthesia, caudal blocks); local anaesthetics (bupivacaine vs ropivacaine, risk of toxicity in children, management of toxic events); adjuvant drugs (clonidine, dexmedetomidine, opioids, ketamine); volume dosing (dermatomal reach, cranial rebound); caudally accessed lumbar or thoracic anaesthesia (contamination risk, verifying catheter placement); and postoperative pain. Caudal blocks are an efficient way to offer perioperative analgesia for painful sub-umbilical interventions. Performed on sedated children, they enable not only early ambulation, but also periprocedural haemodynamic stability and spontaneous breathing in patient groups at maximum risk of a difficult airway. These are important advantages over general anaesthesia, notably in preterm babies and in children with cardiopulmonary co-morbidities. Compared with other techniques of regional anaesthesia, a case for caudal blocks can still be made.

Caudal and intravenous dexmedetomidine similarly prolong the duration of caudal analgesia in children: A randomized controlled trial

BACKGROUND

Dexmedetomidine can prolong the duration of action of a local anesthetic agent, but the route of administration that is the most beneficial remains unclear. The purpose of this study was to compare the clinical effectiveness of caudal or intravenous dexmedetomidine administration on postoperative analgesia in children undergoing inguinal hernia repair given caudal levobupivacaine.

METHODS

This was a prospective, randomized, double-blinded, placebo-controlled trial. Ninety ASA I subjects, aged 2-5 year, undergoing unilateral inguinal hernia repair were enrolled. The children were randomized in a double-blind fashion to three groups. The L-Dcau group received 1 mL/kg of caudal 0.25% levobupivacaine plus 1 μg/kg dexmedetomidine and IV 20 mL saline. The L-Div group received 1 mL/kg of caudal 0.25% levobupivacaine and IV 1 μg/kg dexmedetomidine in 20 mL saline. The L group received 1 mL/kg of caudal 0.25% levobupivacaine and IV 20 mL saline. The primary outcome was the duration of analgesia, which was defined as the time from the caudal block to a Postoperative Pain Scale (CHIPPS) score ≥4. Secondary outcomes were the number of patients requiring rescue analgesia, pain intensity, the incidence of emergence agitation, intraoperative hemodynamic variations, residual motor block, and adverse effects.

RESULTS

The median duration of analgesia in the L-Dcau group was 14.2 hour compared to 6 hour in the L group with a median difference of 8.5 hour [95% CI (6.5, 10.5), P < 0.001]. The median duration of analgesia in the L-Div group was 12.4 hour compared to 6 hour in the L group with a median difference of 6.4 hour [95% CI (4, 8.5), P < 0.001]. Fewer patients in the L-Dcau and L-Div groups required rescue analgesia in the first 24 hour postoperatively compared to the L group, although there was no significant difference between the L-Dcau and L-Div groups for these outcomes. Both dexmedetomidine routes reduced the pain and the incidence of emergence agitation. No bradycardia, hypotension, or motor block was observed in any of the three groups.

CONCLUSION

Caudal and IV dexmedetomidine similarly prolong the duration of analgesia produced by caudal levobupivacaine.

Effect of an Intravenous Dexamethasone Added to Caudal Local Anesthetics to Improve Postoperative Pain: A Systematic Review and Meta-analysis With Trial Sequential Analysis

BACKGROUND

Caudal anesthesia has been used for postoperative pain control in pediatric surgical patients, but the duration of the analgesic effect is occasionally unsatisfactory. Intravenous steroids have been shown to be effective for postsurgical pain management after certain surgeries. The aim of this meta-analysis with trial sequential analysis (TSA) was to evaluate the analgesic effect of steroids in patients administered with caudal anesthesia.

METHODS

This study was a systematic review and meta-analysis. A search of published literature was conducted in the MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials databases and in trial registration sites. Randomized controlled trials that compared intravenous steroids with a placebo in pediatric patients who had received caudal anesthesia for surgery were included in the study. The primary outcomes from the present meta-analysis were the analgesic duration and the number of patients who required rescue analgesics. The analgesic duration and incidence of rescue use were summarized using mean difference or risk ratio with a 97.5% confidence interval (CI), respectively. If the 97.5% CI of the mean difference or risk ratio included a value of 0 or 1, respectively, we considered the difference not to be significant. We used the random effects model to combine the results. Heterogeneity was quantified with the I statistic. The quality of the trials was evaluated using the Cochrane methodology. Moreover, a TSA with a risk of type 1 error of 2.5% and power of 90% was performed. We established the minimum clinically meaningful difference of analgesic duration as 3 hours. The target sample size for meta-analysis was also calculated in the TSA. We also assessed adverse events.

RESULTS

Six trials with 424 patients were included; 211 patients received intravenous steroids. All trials compared dexamethasone of at least 0.5 mg/kg dose with a placebo. Dexamethasone prolonged the duration of caudal analgesia (mean difference, 244 minutes; 97.5% CI, 188-300). Heterogeneity was considerable with an I value of 94.8%. Quality of evidence was very low. The TSA suggested that only 17.0% of the target sample size had been reached, but the cumulative Z score crossed the trial sequential monitoring boundary to indicate a benefit. Rescue use was reported in 4 studies with 260 patients. Rescue use was not significantly reduced in the dexamethasone group (risk ratio, 0.53; 97.5% CI, 0.09-3.30; I, 98.7%). No increase in adverse events was reported.

CONCLUSIONS

Intravenous dexamethasone prolongs the analgesic duration of caudal anesthesia. Trials to investigate the effectiveness of a lower dose of the dexamethasone in prolonging analgesic effects would be of interest. Further trials with a low risk of bias are necessary.