The effect of epidural neostigmine combined with ropivacaine and sufentanil on neuraxial analgesia during labor

Dose-response of epidural ropivacaine with 0.4 μg mL-1 of dexmedetomidine for labor analgesia: A prospective double-blinded study

BACKGROUND

Studies have shown that the ideal dose of epidural dexmedetomidine is 0.4 μg mL-1 for epidural labor analgesia. However, the appropriate dose of ropivacaine when combined with 0.4 μg mL-1 of dexmedetomidine for epidural labor analgesia is still unknown. Therefore, we aimed to determine the dose-response of ropivacaine when using 0.4 μg mL-1 of dexmedetomidine as epidural adjuvant for labor analgesia.

METHODS

One hundred of nulliparous singleton pregnant patients were randomized allocated into 1 of 5 groups with epidural ropivacaine concentration of 0.05%, 0.0625%, 0.075%, 0.0875%, and 0.1%. Labor analgesia was initialed with 12 mL of the mixed study solution. Effective analgesia was defined as a visual analogue scale <10 mm 30 minutes after the initial epidural bolus. The EC50 and EC95 for epidural ropivacaine was calculated by probit regression.

RESULTS

Ninety-three of parturients were involved into the final analysis. Totals of 63.2% (12/19), 73.7% (14/19), 88.9% (16/18), 94.7% (18/19), and 100% (18/18) of parturients in group 0.05, 0.0625, 0.075, 0.0875, and 0.1 received effective epidural labor analgesia. The calculated EC50 and EC95 of epidural ropivacaine were 0.046% (95% CI 0.028-0.054%) and 0.086% (95% CI 0.074-0.137%), respectively.

CONCLUSIONS

Under the condition of the study, a bolus of 12 mL ropivacaine 0.086% and dexmedetomidine 0.4 μg mL-1 could afford 95% of nulliparous singleton pregnant patients without suffering labor pain after a test dose of lidocaine 45 mg.

Neuraxial labor analgesia: is there a place for neuraxial adjuvants beyond opioids

Neuraxial labor analgesia is considered the gold standard technique for analgesia. Ideally, a good neuraxial technique uses dilute local anesthetic solutions to produce effective pain relief with no or minimal motor impairment. Adjuvant drugs that are co-administered with the local anesthetic either epidurally or intrathecally are useful in achieving this goal. The current review focuses on the effectivity and side-effect profile of various commonly used or tested adjuvants.

The Effect of Epidural Nalbuphine Combined With Ropivacaine on Epidural Analgesia During Labor: A Multicenter, Randomized, Double-blind, Controlled Study

OBJECTIVES

The addition of a small dose of opioids during epidural labor analgesia can enhance the local analgesic effect, reduce the dose of local anaesthetic required, and minimize motor blockade. For the treatment of visceral pain, studies have shown that κ-opioid receptor agonist are more effective than μ-receptor agonists. This study compared the effectiveness of epidural nalbuphine and sufentanil in combination with ropivacaine for labor analgesia, respectively.

MATERIALS AND METHODS

We conducted a prospective, randomized, double-blind, multicentre clinical trial. Parturients who requested labor pain relief were randomly assigned to either the nalbuphine group or sufentanil group. After 5 minutes of initial dose, parturients in nalbuphine group received 10 mL 0.1% ropivacaine plus 0.3 mg/mL nalbuphine solution. The sufentanil group received the same ropivacaine dose plus 0.3 μg/mL sufentanil. The primary outcome was the duration of analgesia (the time to the first requirement for additional medication). Secondary outcomes included the ropivacaine dose per hour, and adverse reactions.

RESULTS

Between November 2018 and February 2019, 180 parturients were recruited for the study. The study showed that the duration of analgesia was shorter in the nalbuphine group as compared with the sufentanil group (P=0.040). The ropivacaine dose per hour in nalbuphine group 9.3 (2.4) mg was significantly greater versus sufentanil group 8.4 (2.5) mg (P=0.024). No serious adverse events directly associated with the analgesics were observed.

DISCUSSION

The analgesia effects of 0.3 mg/mL nalbuphine with ropivacaine are inferior to 0.3 μg/mL sufentanil with ropivacaine in labor analgesia. No serious side effects, either in the mother or in the fetus, were observed.

Comparison of Epidural Butorphanol with Neostigmine and Epidural Sufentanyl with Neostigmine for First Stage of Labor Analgesia: A Randomized Controlled Trial

Background:

Epidural administration of neostigmine appears to be safe in the obstetric population. Recently, few studies have concluded 10 μg sufentanil to be an effective adjuvant with epidural neostigmine in providing labor analgesia. However, no study has evaluated the analgesic effect of epidural butorphanol with neostigmine for the same.

Materials and Methods:

The parturients were randomly allocated to one of the three study groups - Group A (n = 30) received butorphanol 1 mg and neostigmine 7 μg/kg. Group B (n = 30) received sufentanil 10 μg and neostigmine 7 μg/kg. Group C (n = 30) received neostigmine 7 μg/kg and 0.9% normal saline. Maternal hemodynamic parameters and fetal heart rate (FHR) were continuously monitored. The level of sensory and motor block, and visual analog scale (VAS) pain score were recorded at designated time points. In addition, the total duration of analgesia, duration of labor, mode of delivery, and any maternal or fetal adverse effects were also recorded.

Statistical Analysis Used:

A one-way analysis of variance (ANOVA) with post hoc Tukey's test was used to compare mean value among the three groups for age, height, weight, gestational age, and cervical dilatation. Repeated measure ANOVA was used to compare mean difference among the time points and also the trend among the various time points for hemodynamic parameters, VAS pain score, and FHR. For inter-group comparison among the groups, post hoc Tukey test was used.

Results:

There was a statistically significant longer effect of analgesic drug in Group B with respect to Group A and C (P < 0.001); however, the parturient in Group C had minimum duration of analgesia. Epidural neostigmine combined with sufentanil produces effective analgesia in early labor (VAS <30 within 10 min in 63.3% of parturient and within 15 min in 83.3% parturient) with average duration of 111.67 ± 24.51 min without motor block or other side effect in mother and fetus. No significant effect was observed in the duration of labor and mode of delivery in-between the two groups, and none of the patients in any group had any maternal or fetal side effects.

Conclusion:

Epidural combination of sufentanil with neostigmine provided better pain relief in terms of the total duration of analgesia and the reduction in VAS pain scores at various time points in the initial 30 min of epidural administration of drugs during the first stage of labor in parturient when compared to the epidural combination of butorphanol with neostigmine.

A systematic review of the effects of adding neostigmine to local anesthetics for neuraxial administration in obstetric anesthesia and analgesia

BACKGROUND

Drugs used in obstetric patients must accomplish two goals: efficacy and safety for both mother and fetus. Neostigmine has been co-administered epidurally and intrathecally with local anesthetics and other adjuncts in the obstetric setting. The aim of this meta-analysis was to assess the efficacy and incidence of adverse events related to the use of neostigmine in obstetric anesthesia.

METHODS

A meta-analysis of randomized-controlled human trials was conducted using the data sources Google Scholar and PubMed (updated 1 November 2014). Inclusion criteria were: random allocation to treatment; comparison of neostigmine or neostigmine with local anesthetics and/or other adjuvants versus placebo or placebo with local anesthetics and/or other adjuvants; and approval by an ethics committee.

RESULTS

The use of neostigmine as an adjuvant in neuraxial anesthesia is associated with a reduction in the dose of local anesthetic during labor analgesia and postoperative analgesia following cesarean section: mean reduction of local anesthetic (ropivacaine or bupivacaine) vs. control -4.08 (95% CI -6.7 to -1.5) mg/h (P=0.002). The risk of nausea was increased vs. control with intrathecal neostigmine (OR 8.99 [95% CI 4.74 to 17.05], P <0.001) but not with epidural neostigmine (OR 0.97 [95% CI 0.46 to 2.05], P=0.94). Use of neuraxial neostigmine was associated with a decrease in the risk of pruritus but there was no increase in the incidence of hypotension, dizziness or sedation and no effect on the incidence of abnormal fetal heart rate patterns or Apgar scores.

CONCLUSIONS

Neuraxial administration of neostigmine significantly reduces local anesthetic consumption without serious adverse side effects to the mother or fetus. However, neostigmine is only recommended for epidural administration as intrathecal use significantly increases the incidence of maternal nausea and vomiting.

The evolution of spinal/epidural neostigmine in clinical application: Thoughts after two decades

Since the first clinical application of analgesia following spinal anticholinesterase by 1940's, several clinical double-blind studies have been conducted to date, where intrathecal doses of neostigmine in humans ranged from 750 to 1 μg, due to side-effects. Conversely, epidural neostigmine has been evaluated in proportionally higher doses and represents an alternative, but still deserves more investigation concerning both acute and chronic pain, as it seems devoid of important side-effects.

Progress in analgesia for labor: focus on neuraxial blocks

Neuraxial analgesia is widely accepted as the most effective and the least depressant method of providing pain relief in labor. Over the last several decades neuraxial labor analgesia techniques and medications have progressed to the point now where they provide high quality pain relief with minimal side effects to both the mother and the fetus while maximizing the maternal autonomy possible for the parturient receiving neuraxial analgesia. The introduction of the combined spinal epidural technique for labor has allowed for the rapid onset of analgesia with minimal motor blockade, therefore allowing the comfortable parturient to ambulate. Patient-controlled epidural analgesia techniques have evolved to allow for more flexible analgesia that is tailored to the individual needs of the parturient and effective throughout the different phases of labor. Computer integrated systems have been studied to provide seamless analgesia from induction of neuraxial block to delivery. New adjuvant drugs that improve the effectiveness of neuraxial labor analgesia while decreasing the side effects that may occur due to high dose of a single drug are likely to be added to future labor analgesia practice. Bupivacaine still remains a popular choice of local anesthetic for labor analgesia. New local anesthetics with less cardiotoxicity have been introduced, but their cost effectiveness in the current labor analgesia practice has been questioned.

Neostigmine decreases bupivacaine use by patient-controlled epidural analgesia during labor: a randomized controlled study

BACKGROUND

Intrathecal neostigmine not only produces analgesia but also severe nausea. In contrast, epidural neostigmine enhances opioid and local anesthetic analgesia without causing nausea. Previous studies examined only single epidural neostigmine bolus administration and did not assess the efficacy of continuous epidural infusion or several aspects of maternal and fetal safety. We therefore tested the hypothesis that epidural neostigmine in combination with bupivacaine by continuous infusion during labor would reduce the amount of bupivacaine required.

METHODS

Twelve healthy women scheduled for elective cesarean delivery were assigned to receive epidural neostigmine, 40 microg (first six subjects) or 80 microg (second six subjects) as a single bolus, with fetal heart rate (FHR) and uterine contractions monitored for 20 min. In a subsequent experiment, 40 healthy laboring women were randomized to receive bupivacaine 1.25 mg/mL alone or with neostigmine 4 microg/mL by patient-controlled epidural analgesia. The primary outcome measure was hourly bupivacaine use.

RESULTS

Epidural neostigmine bolus did not alter baseline FHR, induce contractions, or produce nausea. Epidural neostigmine infusion reduced bupivacaine requirement by 19% in all patients and 25% in those with >4 h of treatment (P < 0.05 for both) but might have contributed to the incidence of mild sedation. Mode of delivery, incidence of maternal nausea, and FHR abnormality were similar between groups.

CONCLUSIONS

These data show that adding epidural neostigmine 4 microg/mL reduces the hourly bupivacaine requirement by 19%-25% with patient-controlled epidural analgesia during labor. Administered as a bolus and by continuous infusion at the studied doses, epidural neostigmine does not cause nausea and does not induce uterine contractions or FHR abnormalities, but mild sedation can occur.

Obstetric spinal analgesia and anesthesia

PURPOSE OF REVIEW

The present overview will try to summarize the most important recent studies performed on spinal analgesia for labor pain treatment and spinal anesthesia for Cesarean section.

RECENT FINDINGS

Attention is focused on pharmacological and technical topics. The interest in demonstrating the benefits of the new local anesthetics over bupivacaine seems to have faded. The search for other adjuvant drugs continues, but it is not clear whether opioids need to be replaced or combined with other adjuvants. A large number of studies are still dealing with vasopressor treatment of hypotension during Cesarean section. There is growing evidence that ephedrine is no longer the vasopressor drug of choice and that phenylephrine should take its place. In technical studies, discussion on combined spinal-epidural versus epidural continues, but it remains difficult to provide definitive evidence that combined spinal-epidural is more advantageous. Also the increased possibility of ambulation has not resulted in benefits other than enhanced maternal satisfaction. Finally, spinal techniques seem to have lost their reputation as being a dangerous choice in patients with severe preeclampsia or cardiac disease.

SUMMARY

The new local anesthetics have established their position in obstetric regional anesthesia, but it remains difficult to demonstrate a superior outcome as compared with bupivacaine. The same is true for combined spinal-epidural and ambulation. Phenylephrine seems to have become the vasopressor of choice in the treatment of hypotension following spinal anesthesia. A more appropriate treatment of hypotension combined with a low-dose technique may enhance the safety of spinal anesthesia in preeclamptic patients or cases of severe cardiac disease.

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.

Neuraxial drug administration: a review of treatment options for anaesthesia and analgesia

Neuraxial drug administration describes techniques that deliver drugs in close proximity to the spinal cord, i.e. intrathecally into the CSF or epidurally into the fatty tissues surrounding the dura, by injection or infusion. This approach was initially developed in the form of spinal anaesthesia over 100 years ago. Since then, neuraxial drug administration has evolved and now includes a wide range of techniques to administer a large number of different drugs to provide anaesthesia, but also analgesia and treatment of spasticity in a variety of acute and chronic settings. This review concentrates on the pharmacological agents used and the clinical basis behind currently utilised approaches to neuraxial drug administration. With regard to local anaesthetics, the main focus is on the development of the enantiomer-specific compounds ropivacaine and levobupivacaine, which provide similar efficacy to bupivacaine with a reduced risk of severe cardiotoxicity. Opioids are the other group of drugs widely used neuraxially, in particular to provide analgesia alone or more commonly in combination with other agents. The physicochemical properties of the various opioids explain the main differences in efficacy and safety between these drugs when used intrathecally, of which morphine, fentanyl and sufentanil are most commonly used. Another group of drugs including clonidine, dexmedetomidine and epinephrine (adrenaline) provide neuraxial analgesia via alpha-adrenergic receptors and are used mainly as adjuvants to local anaesthetics and opioids. Furthermore, intrathecal baclofen is in routine clinical use to treat spasticity in a number of neurological conditions. Beside these established approaches, a wide range of other drugs have been assessed for neuraxial administration to provide analgesia; however, most are in various early stages of investigation and are not used routinely. These drugs include neostigmine, ketamine, midazolam and adenosine, and the conotoxin ziconotide. The latter is possibly the most unusual compound here; it has recently gained registration for intrathecal use in specific chronic pain conditions.

The Effect of a Lidocaine Test Dose on Analgesia and Mobility After an Epidural Combination of Neostigmine and Sufentanil in Early Labor

We previously demonstrated the effectiveness of epidural sufentanil and the cholinesterase inhibitor, neostigmine, to initiate selective labor analgesia. Because the traditional lidocaine plus epinephrine test dose (TD) may alter the effect of subsequent epidural drugs, we undertook this investigation to evaluate the impact of a lidocaine TD on analgesia from a combination of epidural neostigmine plus sufentanil administered in early labor. Eighty healthy parturients were randomly allocated to two groups to receive a 3 mL-TD, either lidocaine 2%-epinephrine (1:200,000) or saline-epinephrine (1:200,000), followed 3 min later by epidural neostigmine 500 microg plus sufentanil 10 microg. Pain scores were recorded for 30 min after injection, as was the time elapsed from initial bolus until request for supplemental analgesia. Thirty minutes after injection, adequacy of motor function was evaluated by the parturient's ability to sit, stand up, bend her knees, and walk. Lidocaine TD hastened the onset (5 min vs 15 min) and increased duration (122 +/- 53 min vs 98 +/- 54 min; P = 0.02) of analgesia from epidural neostigmine plus sufentanil bolus. In contrast, the TD did not significantly impair the ability to sit, stand up, or bend the knees. The ability to ambulate, however, was reduced (57% vs 82%; P = 0.04). In conclusion, a traditional lidocaine TD significantly enhances the analgesic effect from the epidural neostigmine plus sufentanil combination, but affects ambulation in early labor.

The use of neuraxial adjuvant drugs (neostigmine, clonidine) in obstetrics

PURPOSE OF REVIEW

Neuraxial adjuvant drugs are used to improve analgesia and to decrease complications associated with a high dose of a single drug. Opioids are used in routinely, but alpha2-agonists, such as clonidine or cholinesterase inhibitors (neostigmine), have also been used for labour analgesia or to relieve pain following caesarean section. Both drugs possess a common mechanism of action that can be beneficial.

RECENT FINDINGS

Small doses of intrathecal clonidine (30 microg), combined with local anaesthetics and opioids, prolong labour analgesia. Hypotension can occur and must be promptly treated by ephedrine to avoid fetal side effects. Epidural clonidine (60 to 75 microg) produces prolonged analgesia from local anaesthetics and opioids and allows a ropivacaine sparing effect. Intrathecal neostigmine has analgesic properties, but its gastro-intestinal side effects contraindicate its clinical use. Epidural neostigmine, combined with sufentanil or clonidine, initiates labour analgesia (minimum 6 to 7 microg/kg; 500 microg) without side effects, however, and allows a 'mobile epidural'. Epidural and spinal clonidine can be used to improve postcaesarean section analgesia. Epidural neostigmine at the doses studied produces modest analgesia following caesarean section.

SUMMARY

Co-administration of neuraxial drugs may enhance analgesia and reduce the side effects of each drug. Clonidine and neostigmine may be used in obstetrics, under some conditions.

Antibacterial Activity of Clonidine and Neostigmine In Vitro

We conducted an in vitro study to investigate the antibacterial activity of clonidine and neostigmine on common microorganisms encountered during infectious complications after regional anesthesia. Standardized suspensions of Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli were incubated during 1, 3, 6, and 24 h at 37 degrees C with concentrations of 37.5, 75, and 150 microg/mL of clonidine and 125, 250, and 500 microg/mL of neostigmine. After 24 h incubation at 37 degrees C, the colony counts were compared by two-way analysis of variance. The mean colony counts for S. aureus decreased significantly from control as the exposure to clonidine increased (P < 0.05), with a approximately 100% kill at 6 h for the largest concentration (150 microg/mL) and at 24 h for the intermediate concentration (75 microg/mL). Similar results were observed for S. epidermidis, with a approximately 100% kill at 6 h for the largest concentrations (75 and 150 microg/mL). No bactericidal activity of clonidine was observed for E. coli and no bactericidal activity of neostigmine was observed for any of the tested strains. In the conditions of this experiment, clonidine, but not neostigmine, exhibited a concentration-dependent and time-dependent bactericidal activity in vitro on the microorganisms most frequently encountered in infectious complications after regional anesthesia.

What’s new and novel in obstetric anesthesia? Contributions from the 2003 scientific literature

THE PREGNANT PATIENT: Age; maternal disease; prophylactic antibiotics; gastroesophageal reflux; obesity; starvation; genotyping; coagulopathy; infection; substance abuse; altered drug responses in pregnancy; physiological changes of pregnancy. THE FETUS: Fetal monitoring; intrauterine surgery. THE NEWBORN: Breastfeeding; maternal infection, fever, and neonatal sepsis evaluation. OBSTETRIC COMPLICATIONS: Embolic phenomena; hemorrhage; preeclampsia; preterm delivery. OBSTETRIC MANAGEMENT: External cephalic version and cervical cerclage; elective cesarean delivery; fetal malpresentation; vaginal birth after cesarean delivery; termination of pregnancy. OBSTETRIC ANESTHESIA: Analgesia for labor and delivery; anesthesia for cesarean delivery; anesthesia for short obstetric operations; complications of anesthesia. MISCELLANEOUS: Consent; ethics; history; labor support; websites/books/leaflets/journal announcements.

Caudal neostigmine with bupivacaine produces a dose-independent analgesic effect in children

PURPOSE

To evaluate the analgesic efficacy and duration of varying doses of caudal neostigmine with plain bupivacaine and its side effects in children undergoing genito-urinary surgery.

METHODS

In a randomized double-blind prospective study 80 boys aged two to eight years scheduled for surgical repair of hypospadias were allocated randomly to one of four groups (n = 20 each) and received either only caudal 0.25% plain bupivacaine 0.5 mL.kg(-1) (Group I) or 0.25% plain bupivacaine 0.5 mL.kg(-1) with neostigmine (Groups II-IV) in doses of 2, 3 and 4 microg.kg(-1) respectively. Postoperative pain was assessed for 24 hr using an objective pain score. Blood pressure, heart rate, oxygen saturation, total amount of analgesic consumed and adverse effects were also recorded.

RESULTS

The duration of postoperative analgesia in Group I (5.1 +/- 2.3 hr) was significantly shorter than in the other three groups (II -16.6 +/- 4.9 hr; III - 17.2 +/- 5.5 hr; IV - 17.0 +/- 5.8 hr; P < 0.05). Total analgesic (paracetamol) consumption was significantly more in Group I (697.6 +/- 240.7 mg) than in the groups receiving caudal neostigmine (II - 248.0 +/- 178.4; III - 270.2 +/- 180.8 and IV -230.6 +/- 166.9 mg; P < 0.05). Groups II, III and IV were comparable with regards to duration of postoperative analgesia and total analgesic consumption (P > 0.05). Incidence of nausea and vomiting were comparable in all four groups. No significant alteration in vital signs or any other adverse effects were observed.

CONCLUSIONS

Caudal neostigmine (2, 3 and 4 microg.kg(-1)) with bupivacaine produces a dose-independent analgesic effect ( approximately 16-17 hr) in children as compared to those receiving caudal bupivacaine alone (approximately five hours) and a reduction in postoperative rescue analgesic consumption without increasing the incidence of adverse effects.

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

BACKGROUND

The aim of the present pilot study was to compare the analgesic efficacy of S(+)-ketamine either alone or in combination with neostigmine for caudal blockade in pediatric surgery.

METHODS

A total of 40 children were randomly assigned to receive after induction of general anesthesia either caudal S(+)-ketamine 1 mg.kg(-1) (group K, n = 20) or caudal S (+)-ketamine 0.5 mg.kg(-1) plus neostigmine 10 microg.kg(-1) (group KN, n = 20). Anesthesia was maintained with sevoflurane and a laryngeal mask airway (LMA), no additional analgesics were administered. Postoperative pain and sedation were assessed by the Children's Hospital of Eastern Ontario Pain Score and Ramsay scale for 24 h.

RESULTS

No statistical difference in duration of analgesia and sedation was found. Mean duration of postoperative analgesia was 18 +/- 9.4 h in group K and 21.8 +/- 6.7 h in group KN. There was a significantly higher incidence of postoperative vomiting after administration of caudal ketamine with neostigmine (30% group KN Vs 0% group K; P < 0.05).

CONCLUSIONS

This pilot study demonstrates equianalgesic effects on postoperative pain relief in children with both caudal S(+)-ketamine 1 mg.kg(-1) and caudal S(+)-ketamine 0.5 mg.kg(-1) plus neostigmine 10 microg.kg(-1). Further studies are required to confirm adoption of caudal neostigmine into routine clinical practice.

Anaesthetic Agents for Advanced Regional Anaesthesia

Interest in the use of regional anaesthesia, particularly peripheral nerve blocks (PNBs) and continuous PNBs, has increased in recent years. Accompanying this resurgence in interest has been the development of new local anaesthetics and additives designed to enhance block duration and quality. This manuscript provides a literature-based review on accepted uses of local anaesthetics and adjuncts for a variety of regional anaesthesia techniques. A brief review of local anaesthetic pharmacodynamics describes the action of these drugs in preventing nerve depolarisation, thus blocking nerve impulses. Toxic adverse effects of local anaesthetics, specifically CNS and cardiac manifestations of excessive local anaesthetic blood concentrations and the direct neurotoxic properties of local anaesthetics, are discussed generally and specifically for many commonly used local anaesthetics. Clinically useful ester and amide local anaesthetics are evaluated individually in terms of their physical properties and toxic potential. How these properties impact on the clinical uses of each local anaesthetic is explored. Particular emphasis is placed on the long-acting local anaesthetic toxic potential of racemic bupivacaine compared with levobupivacaine and ropivacaine, which are both levorotatory stereoisomers. Guidelines for using ropivacaine and mepivacaine, based on the authors' experience using advanced regional anaesthesia in a busy practice, is provided. Finally, epinephrine (adrenaline), clonidine and other local anaesthetic additives and their rationale for use is covered along with other future possibilities.