Journal of Obstetric Anaesthesia and Critical Care

ORIGINAL ARTICLE
Year
: 2018  |  Volume : 8  |  Issue : 1  |  Page : 16--19

Timing of administration of epidural analgesia and risk of operative delivery in nulliparous women: A case–control randomised study


Ipsita Chattopadhyay, Srabani Basu, Amarendra K Jha 
 Department of Anaesthesiology and Intensive Care Medicine, B.R. Singh Hospital and Centre for Medical Education and Research, Eastern Railway, Kolkata, West Bengal, India

Correspondence Address:
Dr. Ipsita Chattopadhyay
Kamal Residency, Block-Red, Flat no. 201, Green Park, Narendrapur, Kolkata - 700 103, West Bengal
India

Abstract

Background and Aim: Epidural analgesia (EA) offers an effective form of labour analgesia. The time of administration of EA and its relationship with the mode of delivery is controversial. Our study tried to assess whether early initiation of epidural analgesia influences the obstetric outcome in nulliparous women. Materials and Methods: This was a case control, randomised study which included 60 parturients in spontaneous labour divided into two equal groups, the cases and controls. Cases received EA with 10 mL of 0.125% injection bupivacaine, whereas the control group received a systemic opioid (injection pethidine 100 mg intramuscularly) for pain relief. Cases were further divided into parturients receiving EA at a cervical dilatation of 3 cm or less classified as the early epidural group and those receiving EA at 4 cm or more classified as the late epidural group. The modes of delivery for the study population were recorded. Data analysis was done using Wilcoxon two-sample test. P < 0.05 was considered statistically significant. Results: The rate of instrumental vaginal delivery between the early epidural group [95% confidence interval (CI) 0.358–10.821; P = 0.43] and late epidural group (95% CI 0.150–6.055; P = 0.96) was not significantly different. The cesarean-delivery rate was also not significantly different between those receiving early EA (P = 0.95) and late EA (P = 0.58) when compared with control group. Conclusion: This study showed no significant difference in the incidence of caesarean or instrumental delivery for women receiving early epidural analgesia when compared with late epidurals or no EA.



How to cite this article:
Chattopadhyay I, Basu S, Jha AK. Timing of administration of epidural analgesia and risk of operative delivery in nulliparous women: A case–control randomised study.J Obstet Anaesth Crit Care 2018;8:16-19


How to cite this URL:
Chattopadhyay I, Basu S, Jha AK. Timing of administration of epidural analgesia and risk of operative delivery in nulliparous women: A case–control randomised study. J Obstet Anaesth Crit Care [serial online] 2018 [cited 2020 Feb 26 ];8:16-19
Available from: http://www.joacc.com/text.asp?2018/8/1/16/230068


Full Text



 Introduction



Epidural analgesia (EA) offers a safe and effective way of alleviating pain that women experience during child birth. The timing of neuraxial blocks on delivery mode has often been debated. There is continuing controversy over whether early EA increases the rates of operative delivery.[1]

Early data from studies done by Lieberman et al.[2] suggest an association between caesarean delivery and early initiation of neuraxial analgesia. Based on these observations, the American College of Obstetricians and Gynecologists (ACOG) had earlier recommended that EA should be delayed when possible, until the cervix is 4–5 cm dilated.[3] A 2005 Cochrane review demonstrated that EA was associated with increased instrumental vaginal delivery risk compared with non-epidural deliveries.[4] However, systematic reviews later like the one by Marucci et al.,[5] in 2007, reported similar rates for caesarean and instrumental deliveries in the early EA and control groups. An important limitation of the different studies done so far is the lack of methodological uniformity as they have used disparate regimens and cervical dilations for the initiation of EA and women of mixed parity.[6] In addition, in this study, pethidine was chosen as the analgesic in control group in accordance with previous reports which showed it could be equated with EA for pain relief in labour. It is reported that administering pethidine by liberal patient-controlled analgesia regimen is effective in reducing Visual Analogue Scale (VAS) pain scores and only few patients requesting EA because of inadequate analgesia.[7]

This study was conducted with stringent definitions of early EA given at cervical dilatation of 3 cm or less and late EA defined as analgesia given at cervical dilatation of 4 cm or more.[8],[9] EA containing lesser concentrations of local anaesthetic was used as they are associated with a lower risk of operative delivery.[10] To overcome the confounding effect of parity, only nulliparous women were included.

 Materials and Methods



Following institutional ethical committee approval, a case–control randomised study was initiated in a public hospital of eastern India. The study population included nulliparous women with singleton, term pregnancy, free from any obstetric complication presenting in spontaneous labour, who consented to participate in the study. Labour analgesia and its effects were explained to the parturients in detail, and how they would be randomised into any of the two study groups was elucidated. The study was conducted between May 2015 and July 2015, and all who desired labour analgesia and fulfilled the inclusion criteria were eligible to participate after informed written consent.

Exclusion criteria were a non-vertex presentation, preterm labour, any contraindication to opioid analgesia, foetal malpresentations, antepartum haemorrhage, bleeding disorders, premature rupture of membrane, any deformity of the spine, cephalo-pelvic disproportion, known allergy to bupivacaine, and patients on any narcotic medication.

Parturients were randomly assigned to the epidural analgesia group also called as the cases or the systemic analgesia or control group by means of a computer-generated random-number list. Group assignments were kept sealed in opaque, sequentially numbered envelopes that were opened only after the first request of analgesia made by the mothers. Care providers and study population were, however, not blinded to the group assignment.

When parturients requested analgesia, the cervix was examined. In the epidural analgesia group, women receiving EA at cervical dilatation of 3 cm or less were classified as the early epidural group and those receiving EA at cervical dilatation of 4 cm or more were classified as the late epidural group. Analgesia was initiated in the epidural group by an indwelling epidural catheter, after administration of an epidural test dose. EA was initiated in the cases with 10-mL bolus of 0.125% bupivacaine. At the second, third, and subsequent requests for analgesia in the epidural group, intermittent manual top ups of 6–8 mL 0.125% bupivacaine were given.

Analgesia was initiated in the control or systemic-analgesia group with injection pethidine given intramuscularly (100 mg). At the subsequent requests for analgesia, the dose of pethidine administered was 50 mg intramuscularly to a maximum of 200 mg in 4 h. Pethidine was administered till a cervical os dilatation of 7–8 cm of the labour process to minimise the adverse effects on the newborns.

Analgesia was initiated according to the group allocation and only when requested by the parturients regardless of cervical dilatation. No other form of alternative pain relief was given to women, who were allocated to delayed epidurals to cover that period of delay.

We assessed all operative deliveries (caesarean section, vacuum assisted, forceps) because limiting the study to caesarean section would underplay the impact of epidural analgesia on mode of delivery.

Decisions regarding obstetrical management were made by the obstetricians according to maternal or foetal indications. After delivery, Apgar scores were assessed by paediatricians responsible for neonatal resuscitation.

The primary outcome of our study was the method of delivery in the case and control groups. In a pilot study conducted in our department, the risk ratio of caesarean delivery was 7.1 with proportion of caesarean delivery 50%. So with power 90% and α = 0.05, there was a need of 30 study subjects per group. The number of patients required in each group was in the ratio 1:1. Thus, the required sample size for the study was 60. Overall, 30 cases and 30 controls were thus taken for the study. Categorical data were analyzed with the use of a Chi-square test. Wilcoxon two-sample test was used to analyse interval and ordinal data. P < 0.05 was considered statistically significant at two-sided 95% of confidence interval (CI). The values were expressed as mean ± standard deviation. Statistical analysis was done by the Statistical Package for Social Sciences 15 (SPSS Inc., USA).

 Results



In all, 90 women consented to participate. Sixty parturients were included in the study that was found to be meeting the inclusion criteria. The groups were comparable at baseline at the start of the study. Early epidural analgesia was given in 13 (21.6%) of the cases, whereas 17 (28.3%) cases received late EA. Thirty parturients (50%) received systemic analgesia only [Table 1].{Table 1}

The duration of the first stage of labour in the epidural group was significantly reduced with a P value of 0.0163, being statistically significant. The duration of the second stage of labour was comparable in both the groups [Table 2].{Table 2}

We found spontaneous vaginal deliveries in 21, instrumental delivery in 4, and caesarean section in 5 mothers in the no epidural or control group. The early EA group had eight vaginal deliveries, three instrumental deliveries, and two cases of caesarean section. In the late EA group, 11 mothers had spontaneous vaginal delivery, 2 parturients had instrumental deliveries, whereas 4 mothers underwent caesarean sections [Table 3].{Table 3}

No statistically significant difference was seen in the rates of instrumental vaginal delivery between the early epidural group when compared with the control group (95% CI 0.358–10.821; P= 0.43). There were no significant differences in the instrumental delivery rate in the late EA compared with the control group (95% CI 0.150–6.055; P= 0.96). The cesarean-delivery rate was also not significantly different between women receiving early EA and late EA when compared with control group (P = 0.95 and 0.58 respectively) [Table 4].{Table 4}

On reviewing the neonatal Apgar scores at the end of 5 min, it was seen that the mean score of the cases and controls was 8.03 ± 1.10 and 8.03 ± 1.19, respectively, with a P value of 0.824. This implies there was no significant neonatal depression in women who received EA when compared with those who did not [Table 5].{Table 5}

 Discussion



In our study, early or late administration of EA, when compared with the control group, did not result in an increase in the rate of operative delivery.

A clinical finding of importance in this study is that the duration of the first stage of labour was shorter in the EA group when compared with the control group receiving systemic opioid administration. Earlier studies have found that EA is associated with prolongation of first stage of labour.[11] Factors that influence the progress of labour are not well understood. Autonomic imbalance has been suggested as an explanation of the association between EA and prolonged labour seen in the earlier studies.[12] Short duration of first stage may be because of better analgesia with the use of epidural analgesia resulting in decreased inhibitory effect of catecholamines on uterine contractility, and hence a faster cervical dilatation.[13] Another explanation to our finding of a shorter first stage of labour in the epidural group may be because of the use of systemic opioid analgesia that adversely influences labour progress. Opioids decreased uterine activity both in humans in active labour and in pregnant baboons.[14],[15]

The prolonged infusion of an epidural anaesthetic drug may increase the risk of instrumental vaginal delivery by causing motor blockade.[10] In our trial, the rate of instrumental vaginal delivery did not appreciably differ among the groups, although the cases received neuraxial analgesia for a longer period. This was because central neuraxial analgesia initiated and maintained with low-dose epidural bupivacaine is not likely to result in motor blockade.

A positive correlation between EA and the use of oxytocin for augmentation of labour has been reported.[16] In our study, we did not find any significant difference among the subjects in the rate of oxytocin use, but most of the subjects had already received oxytocin before their first request for pain relief, a finding consistent with our pattern of institutional obstetrical management guidelines.

In a previous study, neonates delivered by mothers who were randomly assigned to receive systemic opioid analgesia had lower Apgar scores at 1 min than neonates whose mothers received EA.[17] In our study, the duration of the second stage of labour was comparable in both the groups. Although being slightly prolonged in the EA group, it did not reach statistical significance and neonates seemed safe. We found no deterioration of Apgar scores in them irrespective of whether the mothers received epidural analgesia or systemic opioids.

There are several limitations to our study. We studied nulliparous women in spontaneous labour, and our results may not be reflected in other population groups. In addition, the rapid progress of labour after EA, when compared with systemic analgesia in the control group, may have been affected by the greater cervical dilatation at the initiation of pain relief. Multivariate modeling, however, put forward that the type of analgesia provided was an independent predictor of labour progress.

Different obstetricians and management guidelines followed by them (including the pattern of oxytocin use) may affect the outcome of labour, and we did not adjust for these factors. Moreover, our study was not blinded. It is, however, unlikely that the knowledge of the type of analgesia offered biased obstetricians' decisions regarding the mode of delivery. Cesarean sections were done only when it was indicated by the presence of arrest of descent or arrest of dilatation or in non-reassuring foetal status, and none of these factors was influenced by the type of analgesia.

Techniques for administration of neuraxial analgesia during child birth vary, and the diverse techniques may differently affect the outcome of labour accordingly. For example, EA with bupivacaine at doses of 0.25% resulted in higher rates of instrumental vaginal delivery than bupivacaine given at a dose of 0.0625% with fentanyl.[18] Thus, the results obtained with these regimens may not be applicable to other regimens.

In future, similar studies with the use of local anaesthetics combined with different combinations of opioids must be done, and the progress of labour and neonatal outcome was assessed.

 Conclusion



The results of this randomised control study suggest no statistically significant increased risk of instrumental vaginal delivery or caesarean delivery in women receiving early EA or late EA compared with mothers receiving no epidural analgesia. Fears about an increased risk of adverse obstetric outcomes should not be used to dissuade epidural analgesia in nulliparous women if requested.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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