Ropivacaine 0.25% versus bupivacaine 0.25% for continuous epidural analgesia in labor: a double-blind comparison

Double blind comparison of combination of 0.1% ropivacaine and fentanyl to combination of 0.1% bupivacaine and fentanyl for extradural analgesia in labour

BACKGROUND AND AIMS

Ropivacaine is considered as a safe alternative to bupivacaine for labor analgesia. The aim was to compare epidural ropivacaine and bupivacaine in intermittent doses for obstetric analgesia.

MATERIAL AND METHODS

In this prospective, randomized, double-blind study, 60 women in labor were randomly allocated to receive either bupivacaine 0.1% with fentanyl 2 μg/mL (BF), or ropivacaine 0.1% with fentanyl 2 μg/mL (RF). Bromage scale, loss of cold sensation to ether swab in midclavicular line, visual analog scale were used to test for motor block, sensory block and pain, respectively. Hemodynamic parameters, onset of analgesia, dose requirement of drug to produce analgesia, duration of labor, and incidence of side effects were also recorded. Data were expressed as mean ± standard deviation and analyzed using students unpaired t-test, Chi-square and Mann-Whitney U-tests at P < 0.05.

RESULTS

Both drugs were similar with respect to hemodynamic stability, onset of analgesia, quality of analgesia, sensory blockade, neonatal outcome, requirement of drugs, duration of labor, and incidence of side effects. Three parturient in bupivacaine (B-F) group had a motor block of Bromage 1 and were delivered using forceps. None of the parturient in ropivacaine (R-F) group had any motor block, and all had spontaneous vaginal delivery, but this difference was not statistically significant (P = 0.081).

CONCLUSIONS

Bupivacaine and ropivacaine provide equivalent analgesia in low (0.1%) concentration.

The effect of epidural analgesia on labour, mode of delivery and neonatal outcome in nullipara of India, 2011-2014

AIMS

This study aimed to evaluate the effect of ropivacaine epidural analgesia on duration and outcome of labour in nulliparous parturients of India with parturient not receiving any analgesia.

SETTINGS AND DESIGN

One hundred and twenty nulliparous parturient in established labour at full term with a singleton vertex presentation were assigned to the study. Parturients who request epidural analgesia were allocated in the epidural group (n=60), whereas those not enthusiastic to labour analgesia were allocated in the control group (n=60).

MATERIALS AND METHODS

Epidural analgesia was provided by a bolus injection of 10 ml of ropivacaine 0.2% and 50μg fentanyl and maintained by using a continuous infusion of ropivacaine 0.1% with fentanyl 2μl/ml at a 10ml/hour rate. The outcomes were duration of labour, incidence of cesarean sections and instrumental vaginal delivery and neonatal outcome.

STATISTICAL ANALYSIS USED

Statistical analysis was conducted using unpaired student t-test and chi-square test as required. All tests of significance were performed using two-tailed probability tests. Differences were considered significant when p-value was <0.05.

RESULTS

The two groups were comparable in terms of socio-demographic data. The mean duration of first stage of labour was shorter in epidural group (4.83 ± 1.59 h) compared with control group (5.48 ± 1.56 h) while the duration of second stage of labour was prolong in epidural group (33.13 ± 12.78 min) as compared to control (27.53 ± 11.73 min). Instrumental vaginal or caesarean delivery rate did not increase in the epidural group. The APGAR scores at 5 min were statistically similar in both groups.

CONCLUSION

Epidural analgesia by ropivacaine in Indian nulliparous resulted in shorter duration of first stage and prolongs duration of second stage of labour compared with parturients without analgesia; however, instrumental vaginal or caesarean delivery rate does not increase in the epidural group.

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.

Epidural analgesia for childbirth: effects of newer techniques on neonatal outcome

New low-dose, local anesthetic-opioid combinations, combined spinal epidural analgesia, and new anesthetic drugs, such as ropivacaine and levobupivacaine, have modified the anesthetic practice in obstetric labor analgesia. These new analgesic techniques have less or no neonatal effects when compared with traditional epidural labor analgesia. They also have less effect on mode of delivery, which may in turn affect neonatal outcome. The use of very diluted or low concentrations of local anesthetic solutions may reduce their placental passage and thus the possible subtle neonatal effects. Small doses of epidural or spinal opioids alone or combined with low doses of local anesthetics does not affect the well-being of the neonate at birth. When considering the neonatal outcome, combined spinal epidural analgesia is as well tolerated as low-dose epidural analgesia. Transient fetal heart rate changes have been described immediately after the administration of intrathecal or epidural opioids. Maternal hypotension may also occur at the onset of epidural analgesia. Whether the occurrence of transient fetal heart rate changes or maternal hypotension immediately after the epidural block may influence the neonatal outcome at birth needs verification.

Ropivacaine: an update of its use in regional anaesthesia

Ropivacaine is a long-acting, enantiomerically pure (S-enantiomer) amide local anaesthetic with a high pKa and low lipid solubility which blocks nerve fibres involved in pain transmission (Adelta and C fibres) to a greater degree than those controlling motor function (Abeta fibres). The drug was less cardiotoxic than equal concentrations of racemic bupivacaine but more so than lidocaine (lignocaine) in vitro and had a significantly higher threshold for CNS toxicity than racemic bupivacaine in healthy volunteers (mean maximum tolerated unbound arterial plasma concentrations were 0.56 and 0.3 mg/L, respectively). Extensive clinical data have shown that epidural ropivacaine 0.2% is effective for the initiation and maintenance of labour analgesia, and provides pain relief after abdominal or orthopaedic surgery especially when given in conjunction with opioids (coadministration with opioids may also allow for lower concentrations of ropivacaine to be used). The drug had efficacy generally similar to that of the same dose of bupivacaine with regard to pain relief but caused less motor blockade at low concentrations. Lumbar epidural administration of 20 to 30ml ropivacaine 0.5% provided anaesthesia of a similar quality to that achieved with bupivacaine 0.5% in women undergoing caesarean section, but the duration of motor blockade was shorter with ropivacaine. For lumbar epidural anaesthesia for lower limb or genitourinary surgery, comparative data suggest that higher concentrations of ropivacaine (0.75 or 1.0%) may be needed to provide the same sensory and motor blockade as bupivacaine 0.5 and 0.75%. In patients about to undergo upper limb surgery, 30 to 40ml ropivacaine 0.5% produced brachial plexus anaesthesia broadly similar to that achieved with equivalent volumes of bupivacaine 0.5%, although the time to onset of sensory block tended to be faster and the duration of motor block shorter with ropivacaine. Ropivacaine had an adverse event profile similar to that of bupivacaine in clinical trials. Several cases of CNS toxicity have been reported after inadvertent intravascular administration of ropivacaine, but only 1 case of cardiovascular toxicity has been reported to date. The outcome of these inadvertent intravascular administrations was favourable.

CONCLUSION

Ropivacaine is a well tolerated regional anaesthetic with an efficacy broadly similar to that of bupivacaine. However, it may be a preferred option because of its reduced CNS and cardiotoxic potential and its lower propensity for motor block.

The role of new anesthetic agents

The three anesthetic drugs introduced most recently to the market are sevoflurane, desflurane, and ropivacaine. Sevoflurane and desflurane are both inhalational anesthetic agents and ropivacaine is a local anesthetic agent. Sevoflurane provides a rapid onset and offset of action; it is well tolerated with little airway irritation. It is hemodynamically stable, with low potential for toxicity. Concerns about its interaction with soda lime during low-flow anesthesia with the production of Compound A have not proved to be a clinical problem. While desflurane also provides rapid onset and recovery from anesthesia, it is not as hemodynamically stable as sevoflurane, and also causes airway irritation. Ropivacaine is a unique local anesthetic in that it is supplied as the pure S-enantiomer. It is at least as effective as bupivacaine, with lower toxicity and less motor block for the same degree of sensory block.

What's new in local anaesthetics for obstetric anaesthesia?

Despite its efficacy, bupivacaine has never been considered to be the most suitable agent for achieving anaesthesia and analgesia in the obstetric patient. Ropivacaine is less cardiotoxic than bupivacaine and, at low concentrations, can produce analgesia with minimal motor block, attributes which make it potentially very suitable for use in obstetrics. However, further research is required to ultimately establish ropivacaine's place in obstetric anaesthesia and analgesia. Levobupivacaine, the L isomer of bupivacaine, is of similar potency to bupivacaine but has the advantage of being significantly less cardiotoxic than racemic bupivacaine, which suggests that it might ultimately replace racemic bupivacaine in obstetric practice.