Caudal additives for postoperative pain management in children: S(+)-ketamine and neostigmine

Effect of caudal ketamine on minimum local anesthetic concentration of ropivacaine in children: a prospective randomized trial

Background

Caudal ketamine has been shown to provide an effective and prolonged post-operative analgesia with few adverse effects. However, the effect of caudal ketamine on the minimum local anesthetic concentration (MLAC) of ropivacaine for intra-operative analgesia is unclear.

Methods

One hundred and sixty-nine children were randomized to five groups: Group C (caudal ropivacaine only), Group K_0.25 (caudal ropivacaine plus 0.25 mg/kg ketamine), Group K_0.5 (caudal ropivacaine plus 0.5 mg/kg ketamine), Group K_0.75 (caudal ropivacaine plus 0.75 mg/kg ketamine), and Group K_1.0 (caudal ropivacaine plus 1.0 mg/kg ketamine). The primary outcome was the MLAC values of ropivacaine with/without ketamine for caudal block.

Results

The MLAC values of ropivacaine were 0.128% (0.028%) in the control group, 0.112% (0.021%) in Group K_0.25, 0.112% (0.018%) in Group K_0.5, 0.110% (0.019%) in Group K_0.75, and 0.110% (0.020%) in Group K_1.0. There were no significant differences among the five groups for the MLAC values (p = 0.11). During the post-operative period the mean durations of analgesia were 270, 381, 430, 494, and 591 min in the control, K_0.25, K_{0. 5}, K_0.75, and K_1.0 groups respectively, which shown that control group is significantly different from all ketamine groups. Also there were significant differences between K_0.25 and K_0.75 groups, and between K_1.0 groups and the other ketamine groups.

Conclusions

Adding caudal ketamine to ropivacaine prolong the duration of post-operative analgesia; however, it does not decrease the MLAC of caudal ropivacaine for intra-operative analgesia in children.

Clinical trial registration

ChiCTR-TRC-13003492. Registered on 13 August 2013.

Adjuvants in pediatric regional anesthesia

SUMMARY Local anesthetics have a limited duration of action. Adjuvants are used to prolong the duration of action and to augment analgesia allowing lower concentrations of local anesthetic to be used. Adjuvants have been used more extensively with neuraxial blocks, particularly caudal epidural blocks, but more recently to supplement peripheral nerve blocks. Intrathecal adjuvants are not covered in this review since spinal anesthesia is not widely used in children except in ex-premature infants. Morphine is the historical gold-standard with which other adjuvants are compared. Clonidine is most useful and is becoming increasingly popular, while the side-effect profile of other agents reduces their utility. Concerns with regard to the neurotoxicity of ketamine in animal models has led to its withdrawal in some countries.

Evaluation of preemptive effect of epidural S(+)-ketamine for hysterectomy: plasmatic concentrations of interleukins

BACKGROUND AND OBJECTIVES

Some studies showed that ketamine inhibits the production of cytokines. The objective of this study was to evaluate the preemptive analgesic effect of epidural S(+)-ketamine in hysterectomy and plasmatic cytokines (IL-6, TNF-α and IL-10).

METHOD

A double-blinded study with 29 patients was conducted. Patients in Group 1 received 13 mL of 0.25% bupivacaine with 25mg of S(+)- ketamine 30 minutes before surgical incision and 15 mL of saline solution via the epidural route 30 minutes after. Patients in Group 2 received 15 mL of saline solution 30 minutes before the surgical incision, followed by 13 mL of 0.25% bupivacaine with 25mg of S(+)-ketamine 30 minutes after. Postoperative analgesia was made with epidural bupivacaine and fentanyl. Dipyrone 1 g was used whenever required. The following paramenters were evaluated: concentration of cytokines, intensity of pain, time of first request of analgesic and total quantity of analgesic used.

RESULTS

Time for the first request for analgesics was 61.5 minutes in Group 1 and 69.0 in Group 2, without difference between these groups. There was no difference for total dose of fentanyl used in Group 1 (221.4 μg) and Group 2 (223.3 μg). A similar analgesic effect was obtained in both groups, except in T12 (Group 1 = 2.4±3.2; Group 2 = 5.5±3.4). No differences in concentration of cytokines were observed.

CONCLUSIONS

The epidural injection of 25mg S(+)-ketamine before incision reduced the pain intensity only 12 hours after surgical incision and did not alter concentration of cytokines.

Neuraxial analgesia in neonates and infants: a review of clinical and preclinical strategies for the development of safety and efficacy data

Neuraxial drugs provide robust pain control, have the potential to improve outcomes, and are an important component of the perioperative care of children. Opioids or clonidine improves analgesia when added to perioperative epidural infusions; analgesia is significantly prolonged by the addition of clonidine, ketamine, neostigmine, or tramadol to single-shot caudal injections of local anesthetic; and neonatal intrathecal anesthesia/analgesia is increasing in some centers. However, it is difficult to determine the relative risk-benefit of different techniques and drugs without detailed and sensitive data related to analgesia requirements, side effects, and follow-up. Current data related to benefits and complications in neonates and infants are summarized, but variability in current neuraxial drug use reflects the relative lack of high-quality evidence. Recent preclinical reports of adverse effects of general anesthetics on the developing brain have increased awareness of the potential benefit of neuraxial anesthesia/analgesia to avoid or reduce general anesthetic dose requirements. However, the developing spinal cord is also vulnerable to drug-related toxicity, and although there are well-established preclinical models and criteria for assessing spinal cord toxicity in adult animals, until recently there had been no systematic evaluation during early life. Therefore, in the second half of this review, we present preclinical data evaluating age-dependent changes in the pharmacodynamic response to different spinal analgesics, and recent studies evaluating spinal toxicity in specific developmental models. Finally, we advocate use of neuraxial drugs with the widest demonstrable safety margin and suggest minimum standards for preclinical evaluation before adoption of new analgesics or preparations into routine clinical practice.

Efficacy of bupivacaine-neostigmine and bupivacaine-tramadol in caudal block in pediatric inguinal herniorrhaphy

BACKGROUND

Limited duration of analgesia is among the limitations of single caudal injection with local anesthetics. Therefore, the purpose of this study was to evaluate the effectiveness and safety of bupivacaine in combination with either neostigmine or tramadol for caudal block in children undergoing inguinal herniorrhaphy.

METHODS

In a double-blinded randomized trial, sixty children undergoing inguinal herniorrhaphy were enrolled to receive a caudal block with either 0.25% bupivacaine (1 ml x kg(-1)) with neostigmine (2 microg x kg(-1)) (group BN) or tramadol (1 mg x kg(-1)) (group BT). Hemodynamic variables, pain and sedation scores, additional analgesic requirements, and side effects were compared between two groups.

RESULTS

Duration of analgesia was longer in group BT (17.30 +/- 8.24 h) compared with group BN (13.98 +/- 10.03 h) (P = 0.03). Total consumption of rescue analgesic was significantly lower in group BT compared with group BN (P = 0.04). There were no significant differences in heart rate, mean arterial pressure, and oxygen saturation between groups. Adverse effects excluding the vomiting were not observed in any patients.

CONCLUSION

In conclusion, tramadol (1 mg x kg(-1)) compared with neostigmine (2 microg x kg(-1)) might provide both prolonged duration of analgesia and extended time to first analgesic in caudal block.

Two different doses of caudal neostigmine co-administered with levobupivacaine produces analgesia in children

SUMMARY BACKGROUND

This study was aimed to evaluate the analgesic efficacy duration of analgesia, and side effects of two different doses of caudal neostigmine used with levobupivacaine in children.

METHODS

Sixty boys, between 5 months and 5 years, undergoing genitourinary surgery were allocated randomly to one of three groups (n =20 each). Group I patients received caudal 0.25% levobupivacaine (1 ml.kg(-1)) alone. Groups II and III patients received neostigmine (2 and 4 microg.kg(-1) respectively) together with levobupivacaine used in the same does as Group I. Pain scores were assessed using Children's and Infant's Postoperative Pain Scale (CHIPPS) at 15th (t(1)) min after arrival to postanesthetic care unit, and 1st (t(2)), 2nd (t(3)), 3rd (t(4)), 4th (t(5)), 8th (t(6)), 16th (t(7)), and 24th (t(8)) hour postoperatively. Duration of analgesia, amount of additional analgesic (paracetamol), score of motor blockade and complications were recorded for 24 h postoperatively, and compared between groups.

RESULTS

CHIPPS scores were higher during t(2), t(3), t(6), t(7), and t(8) periods, duration of analgesia was shorter, and total analgesic consumption was higher in Group I compare to neostigmine groups (P < 0.05). Duration of postoperative analgesia and total analgesic consumption were similar in Groups II and III (P > 0.05). Adverse effects were not different between three groups.

CONCLUSIONS

Caudal neostigmine in doses of 2 and 4 microg.kg(-1) with levobupivacaine extends the duration of analgesia without increasing the incidence of adverse effects, and 2 microg.kg(-1) seems to be the optimal dose, as higher dose has no further advantages.

Use of neostigmine in the management of acute postoperative pain and labour pain: a review

Neostigmine is a parasympathomimetic agent that has been recently investigated for use as an adjunct analgesic agent in the perioperative and peripartum period. A number of studies have investigated the intrathecal, epidural, caudal and intra-articular routes of administration of this agent, as well as the addition of neostigmine to local anaesthetics used for brachial plexus block and intravenous regional anaesthesia. While the intrathecal administration of neostigmine produced useful analgesic effects in the postoperative period in some studies, the high incidence of adverse events, mainly nausea and vomiting, limit the clinical usefulness of this route of administration. Several studies investigated the postoperative analgesic effects of epidural neostigmine using a number of different regimens. Overall, this route of administration appeared to improve postoperative analgesia in most studies without increasing the incidence of adverse events, and merits further research. Neuraxial administration of neostigmine appears to be safe in the obstetric population, with no reported adverse effects in the mother or fetus. While intrathecal administration is limited by a high incidence of nausea and vomiting in this patient population, the epidural route appears more promising and requires further investigation. The addition of neostigmine to caudal local anaesthetics was associated with improved postoperative analgesia in a number of studies. A dose of 2 microg/kg proved to be effective in several studies but was associated with an increased incidence of vomiting in some studies. Intra-articular administration of neostigmine 500microg produced a useful analgesic effect in the postoperative period in several studies and was not associated with an increase in the incidence of adverse effects. Studies investigating the efficacy of adding neostigmine to the local anaesthetics used for brachial plexus block and intravenous regional anaesthesia reported conflicting results. Further studies are required to determine the place of the administration of neostigmine by these routes.

Pediatric acute pain management

Children are benefiting from the advances made in developmental neurobiology and analgesic pharmacology over the past few decades. Heightened public awareness and increased political pressure from external regulatory agencies are helping to maintain the momentum in improving pediatric pain management. As a result, methods of assessing and managing children's pain are being refined, and new modalities of pain relief are being explored. This review summarizes selected current topics in pediatric acute pain management, with the major emphasis on acute postoperative pain management.

Neuropathological findings after continuous intrathecal administration of S(+)-ketamine for the management of neuropathic cancer pain

Questions have been raised about the potential neurotoxicity of the neuraxial use of ketamine although ketamine and its active enantiomer S(+)-ketamine have been used intrathecally and epidurally (caudally) for the management of perioperative pain and in a variety of chronic pain syndromes. Clinical experience following neuraxial administration of S(+)-ketamine has been documented without reference to local central nervous system toxicity following this approach. In addition, there are no preclinical safety data regarding stability, compatibility, and neurotoxicity on intrathecal use of single S(+)-ketamine or combinations of S(+)-ketamine, morphine, bupivacaine, and clonidine. In the present case, the continuous intrathecal administration of S(+)-ketamine, in combination with morphine, bupivacaine, and clonidine resulted in adequate pain relief in a patient suffering from intractable neuropathic cancer pain. However, postmortem observation of the spinal cord and nerve roots revealed severe histological abnormalities including central chromatolysis, nerve cell shrinkage, neuronophagia, microglial upregulation, and gliosis. Based on our results, neuraxial administration of S (+)-ketamine cannot be recommended for clinical practise before a systematic study of toxicology of neuraxial S(+)-ketamine in animals or humans has been performed.

Caudal analgesia and anesthesia techniques in children

PURPOSE OF REVIEW

Caudal epidural blockade remains the cornerstone of pediatric regional anesthesia. In this article we provide a comprehensive review of the recent developments in caudal anesthesia in infants and children.

RECENT FINDINGS

Research has focused on prolonging the duration of single-shot caudal blocks and accurately positioning continuous caudal catheters. New local anesthetics with similar potencies but less toxicity have been introduced. Opioids prolong the duration of analgesia of local anesthetic, but have also been associated with unacceptable side effects, particularly in pediatric outpatients. Various non-opioid adjuncts with more favorable side-effect profiles may increase the duration of analgesia. New ultrasound and nerve-stimulation techniques have been developed to accurately guide epidural catheters to a specific spinal level.

SUMMARY

The addition of ketamine or clonidine to a caudal local anesthetic prolong the duration of the block. However, a preservative-free preparation of ketamine that is suitable for neuraxial use is not widely available. Ultrasound imaging and electrical stimulation are promising options to accurately position a caudal needle. However, because ultrasound imaging is more difficult in older children, nerve stimulation is a more-suitable technique to accurately guide caudal catheters in this patient population. Although complications associated with caudal block are rare, the risks and benefits must be carefully considered on an individual basis.