0.2% ropivacaine with fentanyl in the management of labor analgesia: A case study of 30 parturients.

BACKGROUND: Epidural infusion of 0.2% ropivacaine is recommended by the manufacturers for labor analgesia. AIMS: The aim of this study is to evaluate the analgesic efficacy, degree of motor blockade, obstetric outcome in the form of incidence of normal vaginal, assisted vaginal and lower segment cesarean section. SETTINGS AND
DESIGN: Pilot study.
MATERIALS AND METHODS: In this pilot study, 30 nulliparous parturients in active labor had epidural analgesia established using 0.2% ropivacaine with 25 mcg fentanyl for initiation when cervical dilatation was 3-4 cm and then analgesia was maintained with 0.2% ropivacaine at 10 ml/h till the delivery of baby. STATISTICAL ANALYSIS: It was done by Wilcoxon sign rank test and paired t-test as applicable.
RESULTS: There was a significant difference (P < 0.05) between prebolus, postbolus and postinfusion with respect to visual analog score. There was a significant difference (P > 0.05) between prebolus, postbolus, and postinfusion with respect to Bromage motor score, (Wilcoxon sign rank test). Six out of 30 paturients complained of tingling and heaviness in lower limbs after continuous infusion of 2-2.5 h.
CONCLUSION: We conclude that 0.2% ropivacaine (8 ml) with fentanyl 25 mcg is good for initiation of ambulatory labor analgesia. But for maintenance of labor analgesia lower concentration of ropivacaine may be preferred.

INTRODUCTION

Labour analgesia with use of epidural local anaesthetics and opioids is routinely used techquine for pain relief during labour since many years.[1]

The purpose of this study was to study analgesic efficacy, degree of motor blockade with ropivacaine 0.2% with 25 mcg of fentanyl.

Study the obstetric outcome in terms of incidence of operative (lower segment cesarean section [LSCS]), normal vaginal, assisted vaginal deliveries and duration of 2nd stage.

To study the immediate neonatal outcome, cardiovascular safety and abnormal fetal heart patterns arising from ropivacaine.

With the use of local anesthetic agents (LA), labor analgesia is blessing to parturients by the science with which she can take an active part in the process of labor.

Unrelieved stress in labor produces increased plasma cortisol and catecholamine concentration and the cause reduction in uteroplacental blood flow. Of all labor analgesic techniques, epidural analgesia is the most effective form of analgesia and has become the gold standard in obstetric care.

Study by Owen et al.,[2] showed that there is no difference in the amount of local anaesthetics required by parturients controlled epidural analgesic when identical concentrations of bupivacaine and ropivacain were used.

Study by Bernard, Le Roux[3] found there is no change in maternal expulsive effort, instrumental delivery, and neonatal outcome when ropivacain and fentanyl given in patient controlled analgesia. Similarly there is no any no any difference in neonatal outcome by using Ropivacain vs Bupivacain.[4] But motor block was more frequent with bupivacaine then ropivacain.[56]

MATERIALS AND METHODS

Protocol was approved by the Institutional Ethical Committee and written informed consent was obtained from each parturient before she requested for epidural analgesia.

Inclusion criteria

Thirty American Society of Anesthesiologists I/II laboring nulliparous with term cephalic singleton pregnancies, woman in active labor who were having contractions at least once in 5 min with cervical dilation 3–4 cm.

Exclusion criteria

Parturients having preeclampsia, insulin-dependent diabetes mellitus, medical contraindication for labor analgesia, fetal distress, fetal anomalies, antepartum hemorrhages were excluded from study.

Before the placement of the epidural catheter, parturients were asked to quantify their pain at the peak of uterine contraction on the verbal scale of 0–10 with 0 = no pain and 10 = unbearable pain.

Intravenous access, vital parameters were noted before giving block.

Prehydration was done with 500 ml of Ringer's lactate solution. All epidural catheters were placed with the woman in sitting position, using 18-gauge Tuohy needle.

Epidural space was identified by loss of resistance technique to air via midline approach at L3-L4 interspace.

Epidural catheter inserted and kept 3 cm in the epidural space. Negative aspiration for blood and cerebrospinal fluid confirms epidural placement of the catheter. Catheter secured on the back and parturient allowed to be in the supine position.

All parturients received 0.2% ropivacaine 8 ml and fentanyl 25 mcg as bolus followed by infusion of 0.2% ropivacaine at rate of 10 ml/h after half an hour of bolus.

Monitoring of pulse rate, noninvasive blood pressure, fetal heart rate, Bromage motor score (BMS) for motor block (Gd1 = free movements of legs and feet, [nil = 0%] Gd2 = just able to flex knee with free movements of feet [partial = 33%] Gd3 = unable to flex knee, but with free movements of feet [almost complete 66%] Gd4 = unable to move legs or feet [complete 100%]).

Oxygen saturation of blood (SpO2), extent of sensory block measured by pinprick method for every 10 min up to ½ h and then every half hourly till delivery of baby and expulsion of the placenta.

Analgesia was assessed by asking parturient, whether she felt pain at the peak of uterine contraction, and she was asked to rate her level of pain on the same verbal scale.

Analgesia was considered to be adequate if she reported acceptable pain relief.

A volume of 4 ml of 0.2% ropivacaine bolus was given when visual analog score (VAS) >4 or on parturints demand.

Duration of 1st, 2nd, and 3rd stage, mode of delivery, incidence of assisted labor and LSCS, APGAR score of baby noted.

During the course of labor, all parturients were encouraged to walk, sit and change the positions in bed.

All parturients were monitored for headache, backache, local tenderness, and satisfaction score on a four point scale, (1 = excellent, 2 = good, 3 = fair, 4 = poor).

Statistical analysis was done by Wilcoxon sign rank test for the BMS. Paired t-test was used for VAS. P < 0.05 was considered significant. Other values are described as mean ± standard deviation.

RESULTS

Table 1 shows the demographic profile if patients. Table 2 shows the extent of sensory block. BMS is shown in Table 3. Using Wilcoxon sign rank test P > 0.05, there is no significant difference between prebolus and postinfusion at 30th min to 5th h with respect to BMS. Table 4 shows VAS. Using paired t-test P < 0.05 there for,

Table 1

Demographic profile

Table 2

Extent of sensory block

Table 3

Distribution of patients with respect to BMS

Table 4

Comparison of VAS in prebolous with postbolous and postinfusion

There is a significant difference between prebolus and postbolus at 10th min and 20th min with respect to VAS.

There is a significant difference between prebolus and postinfusion at 30th min to 5th h. with respect to VAS Table 5 shows the distribution of patients with respect to mode of delivery. Table 6 shows the duration of labor.

Table 5

Distribution of patients with respect to mode of delivery

Table 6

Duration of labor

DISCUSSION

Initial studies of ropivacain suggested that it may be less cardiotoxic and produces less motor block then bupivacaine.

Scott et al.,[7] found in human volunteers that larger doeses of iv ropivacain then bupivacaine was tolerated before the onset of neurologic symptoms.

Trend among obstetric anesthesiologist is to use the lowest possible concentration of LA that offers adequate pain relief for labor analgesia, which reduces the resultant motor block, and decrease the incidence of instrumental deliveries or LSCS.

Study by Pinder et al.,[8] states that ropivacain cant be less potent then then bupivacaine as less less supplemental analgesia was needed in ropivacain group. This is due to longer half life of ropivacain then bupivacaine.

Studies by Justin et al.,[9] stated that local anaesthetics and opioid combination were shown to be more effective in labour analgesia as effects started rapidly and lasted longer when compared with local anaesthetics given alone.[101112] Similarly when local anaesthetics are used in low concentration, sufficient analgesia cant be obtained especially in second stage of labour.[13]

Studies by Bobod, et al.,[14] stated parturients receiving extradural infusion of 0.125% bupivacaine 10 ml/hr required no or only one top up during labour procsss.

Yagkov Beilin et al.,[15] showed if one select ropivacaine as a sole anesthetic agent for labor analgesia the minimal concentration should be 0.2%.

Bee et al.,[16] established epidural analgesia with 0.2% ropivacaine and then started epidural infusion of either 0.1%, 0.2%, and 0.1% with 2 mcg/ml fentanyl, found 0.1% ropivacaine alone at rate of 10 ml/h provided analgesia in 1st stage of labor and that the addition of 2 mcg/ml fentanyl to that concentration improved analgesia to a quality similar to 0.2% ropivacaine.

So we decided to select 0.2% ropivacaine for initiation and maintenance of labor analgesia.

Opioids reduce LA requirement in dose-dependent manner so we added fentanyl 25 mcg when VAS > 7–8 so it reduces the requirement of volume and concentration of LA and enhances the analgesic effect of LA.

Sia et al.,[17] compared effectiveness of 0.2% and 0.125% ropivacaine in patient-controlled epidural analgesia and reported that sufficient analgesia had been obtained in both concentrations, but motor block had been less in low concentration of ropivacaine.

With a low concentration of LA minimal motor block fetal head malposition's can be obtained. On the other hand, when LA is used in low concentration, sufficient analgesia can’t be obtained especially in 2nd stage. Perineal pain can’t be relieved unless high concentration of LA is used. In this case, an increase in motor block density is seen.

In our study, 6 out of 30 parturient c/o tingling and heaviness in both lower limb after 2–2.5 h of starting infusion. We assessed the sensory level and stopped the infusion. Infusion restarted after 60 min.

Some authors found the duration of 1st stage of labor shortened by approximately 2 h in ropivacaine 0.1% than in bupivacaine 0.1%.

In our study duration of labor from 3 to 4 cm cervical dilatation to full dilatation was 2.48 h. Second stage 34 min, and 3rd stage was 9.36 min.

53.3% parturients underwent normal vaginal delivery. 30% needed assisted vaginal in form of low out let forceps delivery, ventouse application and 16.6% needed LSCS for obstetric reasons.

CONCLUSION

About 0.2% of ropivacaine with 25 mcg of fentanyl is very good drug for initiation of ambulatory labor analgesia. But for maintenance of labor analgesia lower concentrations of ropivacaine is preferred.