Does early administration of epidural analgesia affect obstetric outcome in nulliparous women who are receiving intravenous oxytocin?

A Review of the Impact of Obstetric Anesthesia on Maternal and Neonatal Outcomes

Obstetric anesthesia has evolved over the course of its history to encompass comprehensive aspects of maternal care, ranging from cesarean delivery anesthesia and labor analgesia to maternal resuscitation and patient safety. Anesthesiologists are concerned with maternal and neonatal outcomes, and with preventing and managing complications that may present during childbirth. The current review will focus on recent advances in obstetric anesthesia, including labor anesthesia and analgesia, cesarean delivery anesthesia and analgesia, the effects of maternal anesthesia on breastfeeding and fever, and maternal safety. The impact of these advances on maternal and neonatal outcomes is discussed. Past and future progress in this field will continue to have significant implications on the health of women and children.

[Recent standards in management of obstetric anesthesia]

The following article contains information not only for the clinical working anaesthesiologist, but also for other specialists involved in obstetric affairs. Besides a synopsis of a German translation of the current "Practice Guidelines for Obstetric Anaesthesia 2016" [1], written by the American Society of Anesthesiologists, the authors provide personal information regarding major topics of obstetric anaesthesia including pre-anaesthesia patient evaluation, equipment and staff at the delivery room, use of general anaesthesia, peridural analgesia, spinal anaesthesia, combined spinal-epidural anaesthesia, single shot spinal anaesthesia, and programmed intermittent epidural bolus.

Practice Guidelines for Obstetric Anesthesia

The American Society of Anesthesiologists Committee on Standards and Practice Parameters and the Task Force on Obstetric Anesthesia and the Society for Obstetric Anesthesia and Perinatology present an updated report of the Practice Guidelines for Obstetric Anesthesia.

Supplemental Digital Content is available in the text.

Early versus late initiation of epidural analgesia for labour

BACKGROUND

Pain during childbirth is arguably the most severe pain some women may experience in their lifetime. Epidural analgesia is an effective form of pain relief during labour. Many women have concerns regarding its safety. Furthermore, epidural services and anaesthetic support may not be available consistently across all centres. Observational data suggest that early initiation of epidural may be associated with an increased risk of caesarean section, but the same findings were not seen in recent randomised controlled trials. More recent guidelines suggest that in the absence of a medical contraindication, maternal request is a sufficient medical indication for pain relief during labour. The choice of analgesic technique, agent, and dosage is based on many factors, including patient preference, medical status, and contraindications. There is no systematically reviewed evidence on the maternal and foetal outcomes and safety of this practice.

OBJECTIVES

This systematic review aimed to summarise the effectiveness and safety of early initiation versus late initiation of epidural analgesia in women. We considered the obstetric and fetal outcomes relevant to women and side effects of the treatments, including risk of caesarean section, instrumental birth and time to birth.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (12 February 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 1), MEDLINE (January 1966 to February 2014), Embase (January 1980 to February 2014) and reference lists of retrieved studies.

SELECTION CRITERIA

We included all randomised controlled trials involving women undergoing epidural labour analgesia that compared early initiation versus late initiation of epidural labour analgesia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, extracted the data and assessed the trial quality. Data were checked for accuracy.

MAIN RESULTS

We included nine studies with a total of 15,752 women.The overall risk of bias of the studies was low, with the exception of performance bias (blinding of participants and personnel).The nine studies showed no clinically meaningful difference in risk of caesarean section with early initiation versus late initiation of epidural analgesia for labour (risk ratio (RR) 1.02; 95% confidence interval (CI) 0.96 to 1.08, nine studies, 15,499 women, high quality evidence). There was no clinically meaningful difference in risk of instrumental birth with early initiation versus late initiation of epidural analgesia for labour (RR 0.93; 95% CI 0.86 to 1.01, eight studies, 15,379 women, high quality evidence). The duration of second stage of labour showed no clinically meaningful difference between early initiation and late initiation of epidural analgesia (mean difference (MD) -3.22 minutes; 95% CI -6.71 to 0.27, eight studies, 14,982 women, high quality evidence). There was significant heterogeneity in the duration of first stage of labour and the data were not pooled.There was no clinically meaningful difference in Apgar scores less than seven at one minute (RR 0.96; 95% CI 0.84 to 1.10, seven studies, 14,924 women, high quality evidence). There was no clinically meaningful difference in Apgar scores less than seven at five minutes (RR 0.96; 95% CI 0.69 to 1.33, seven studies, 14,924 women, high quality evidence). There was no clinically meaningful difference in umbilical arterial pH between early initiation and late initiation (MD 0.01; 95% CI -0.01 to 0.03, four studies, 14,004 women, high quality evidence). There was no clinically meaningful difference in umbilical venous pH favouring early initiation (MD 0.01; 95% CI -0.00 to 0.02, four studies, 14,004 women, moderate quality evidence).

AUTHORS' CONCLUSIONS

There is predominantly high-quality evidence that early or late initiation of epidural analgesia for labour have similar effects on all measured outcomes. However, various forms of alternative pain relief were given to women who were allocated to delayed epidurals to cover that period of delay, so that is it hard to assess the outcomes clearly. We conclude that for first time mothers in labour who request epidurals for pain relief, it would appear that the time to initiate epidural analgesia is dependent upon women's requests.

Neuraxial analgesia effects on labour progression: facts, fallacies, uncertainties and the future

Approximately 60% of women who labour in the USA receive some form of neuraxial analgesia, but concerns have been raised regarding whether it negatively impacts the labour and delivery process. In this review, we attempt to clarify what has been established as truths, falsities and uncertainties regarding the effects of this form of pain relief on labour progression, negative and/or positive. Additionally, although the term 'epidural' has become synonymous with neuraxial analgesia, we discuss two other techniques, combined spinal-epidural and continuous spinal analgesia, that are gaining popularity, as well as their effects on labour progression.

[Impact on the implementation of patient controlled epidural analgesia for pain management during labor. A survey in a university hospital in Chile]

OBJECTIVE

Analgesia for labor is a legal obligation in Chile. In our institution we implemented patient controlled analgesia for pain relief during labor. We describe the perception of the several professionals involved in the medical care of patients in labor in terms of effectiveness, usefulness, satisfaction, and safety.

MATERIAL AND METHODS

A self-reported questionnaire was given to the professionals involved, and the obstetrical and neonatal outcomes were recorded along with the workload indices. Twenty-five structured questions were presented with a Likert type score to evaluate analgesia quality, workload of professionals involved, adverse effects, patient satisfaction, and healthcare workers satisfaction. Finally, a question was asked about the overall perception.

RESULTS

We found that the overall perception of the analgesic technique was (mean) 6.0 (SD) (0.88). A decrease in the anesthesiologist workload was observed, without affecting obstetric outcomes.

CONCLUSION

Considering the study design limitations, absence of knowledge of economical impact, and the satisfaction level of patients under standard epidural analgesia, we recommend the patient controlled analgesia technique due to its good obstetric outcomes, general satisfaction and workload decrease.

Controversies in obstetric anesthesia

Obstetric anesthesia has become a widely evidence-based practice, with an increasing number of specialized anesthesiologists and a permanent research production. We believe that with the review of commonly discussed and controversial points the reader will be able to incorporate an evidence-based practice into their routine and offer to parturients and their babies a safe, reliable and consistent anesthesia care.

[Epidural analgesia in obstetrics: is there an effect on labor and delivery?]

BACKGROUND AND OBJECTIVE

Epidural analgesia is routinely used in obstetrics but has been blamed for possible effects on labor that lead to greater use of instruments or conversion to cesarean delivery. We aimed to assess this possibility in a cohort of obstetric patients receiving or not receiving epidural analgesia.

PATIENTS AND METHODS

Prospectively enrolled full-term obstetric patients were distributed in 2 groups according to whether they received epidural analgesia or not. We compared maternal and fetal characteristics, obstetric variables, and type of delivery between groups to record the likely causes of difficult labor and delivery and detect a possible influence of epidural analgesia.

RESULTS

Of a total of 602 patients, 462 received epidural analgesia and 140 did not. Epidural analgesia was related to a higher rate of use of instruments but not cesareans (P < .01) and more frequent need for oxytocin (30.7% of the epidural analgesia group vs 0% of the group receiving no epidural analgesia, P < .001). The women receiving analgesia also had a longer mean (SD) duration of the dilatation phase of labor (6.4 [4.2] hours in the epidural group vs 4.7 [3.5] hours in the no-epidural group, P < .01) and of the expulsion phase (1.0 [0.6] hours vs 0.7 [0.6] hours, respectively; P<.01). We observed no effects on the incidence of tearing, rate of episiotomy, or other variables. Predictors of instrumentation or conversion to cesarean delivery were longer duration of the first phase (odds ratio [OR] 1.2; 95% confidence interval [CI], 1.1-1.3), longer duration of the second phase (OR 2.3; 95% CI, 1.3-3.9), and maternal obesity (OR, 1.1; 95% CI, 0.9-1.2). Previous deliveries and initiation of epidural analgesia after the fetus has reached Hodge's first plane decreased risk 2.7-fold and 3.03-fold, respectively.

CONCLUSIONS

Although epidural analgesia has traditionally been associated with a higher incidence of difficult labor and delivery, this association was not unequivocally evident in this cohort of patients. The apparent increase seems to be attributable to such obstetric factors as longer duration of stages of labor, higher body mass index, and first delivery.

Advances in labor analgesia

The pain of childbirth is arguably the most severe pain most women will endure in their lifetimes. The pain of the early first stage of labor arises from dilation of the lower uterine segment and cervix. Pain from the late first stage and second stage of labor arises from descent of the fetus in the birth canal, resulting in distension and tearing of tissues in the vagina and perineum. An array of regional nerve blocks, systemic analgesic, and nonpharmacologic techniques are currently used for labor analgesia. Nonpharmacologic methods are commonly used, but the effectiveness of these techniques generally lacks rigorous scientific study. Continuous labor support has been shown to decrease the use of pharmacologic analgesia and shorten labor. Intradermal water injections decrease back labor pain. Neuraxial labor analgesia (most commonly epidural or combined spinal-epidural) is the most effective method of pain relief during childbirth, and the only method that provides complete analgesia without maternal or fetal sedation. Current techniques commonly combine a low dose of local anesthetic (bupivacaine or ropivacaine) with a lipid soluble opioid (fentanyl or sufentanil). Neuraxial analgesia does not increase the rate of cesarean delivery compared to systemic opioid analgesia; however, dense neuraxial analgesia may increase the risk of instrumental vaginal delivery.

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.

Intravenous oxytocin alone for cervical ripening and induction of labour

BACKGROUND

Oxytocin is the commonest induction agent used worldwide. It has been used alone, in combination with amniotomy or following cervical ripening with other pharmacological or non-pharmacological methods.

OBJECTIVES

To determine the effects of oxytocin alone for third trimester cervical ripening and induction of labour in comparison with other methods of induction of labour or placebo/no treatment.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (January 2009) and bibliographies of relevant papers.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing intravenous oxytocin with placebo or no treatment, or with prostaglandins (vaginal or intracervical) for third trimester cervical ripening or labour induction.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility and carried out data extraction.

MAIN RESULTS

Sixty-one trials (12,819 women) are included.When oxytocin inductions were compared with expectant management, fewer women failed to deliver vaginally within 24 hours (8.4% versus 53.8%, risk ratio (RR) 0.16, 95% confidence interval (CI) 0.10 to 0.25). There was a significant increase in the number of women requiring epidural analgesia (RR 1.10, 95% CI 1.04 to 1.17). Fewer women were dissatisfied with oxytocin induction in the one trial reporting this outcome (5.9% versus 13.7%, RR 0.43, 95% CI 0.33 to 0.56).Compared with vaginal prostaglandins, oxytocin increased unsuccessful vaginal delivery within 24 hours in the two trials reporting this outcome (70% versus 21%, RR 3.33, 95% CI 1.61 to 6.89). There was a small increase in epidurals when oxytocin alone was used (RR 1.09, 95% CI 1.01 to 1.17).Most of the studies included women with ruptured membranes, and there was some evidence that vaginal prostaglandin increased infection in mothers (chorioamnionitis RR 0.66, 95% CI 0.47 to 0.92) and babies (use of antibiotics RR 0.68, 95% CI 0.53 to 0.87). These data should be interpreted cautiously as infection was not pre-specified in the original review protocol.When oxytocin was compared with intracervical prostaglandins, there was an increase in unsuccessful vaginal delivery within 24 hours (50.4% versus 34.6%, RR 1.47, 95% CI 1.10 to 1.96) and an increase in caesarean sections (19.1% versus 13.7%, RR 1.37, 95% CI 1.08 to 1.74) in the oxytocin group.

AUTHORS' CONCLUSIONS

Comparison of oxytocin with either intravaginal or intracervical PGE2 reveals that the prostaglandin agents probably increase the chances of achieving vaginal birth within 24 hours. Oxytocin induction may increase the rate of interventions in labour.A suggestion that for women with prelabour rupture of membranes induction with vaginal prostaglandin may increase risk of infection for mother and baby warrants further study.

Oxytocin for induction of labor

Oxytocin is the most common pharmacologic agent used for the induction and augmentation of labor. Oxytocin protocols can be divided into high-dose and low-dose protocols depending on the initial dose and the amount and rate of sequential increase in dose. Despite the frequency with which oxytocin in used in clinical practice, there is little consensus regarding which protocol is most appropriate. The purpose of this chapter is to review the most current data concerning recommendations for the use of oxytocin in the induction of labor, including cases of intrauterine fetal demise and vaginal birth after cesarean.

Early versus late initiation of epidural analgesia in labor: does it increase the risk of cesarean section? A randomized trial

OBJECTIVE

To determine whether early initiation of epidural analgesia in nulliparous women affects the rate of cesarean sections and other obstetric outcome measures.

STUDY DESIGN

A randomized trial in which 449 at term nulliparous women in early labor, at less than 3 cm of cervical dilatation, were assigned to either immediate initiation of epidural analgesia at first request (221 women), or delay of epidural until the cervix dilated to at least 4 cm (228 women).

RESULTS

At initiation of the epidural the mean cervical dilatation was 2.4 cm in the early epidural group and 4.6 cm in the late group (P < 0.0001). The rates of cesarean section were not significantly different between the groups--13% and 11% in the early and late groups, respectively (P = 0.77). The mean duration from randomization to full dilatation was significantly shorter in the early compared to the late epidural group--5.9 hours and 6.6 hours respectively (P = 0.04). When questioned after delivery regarding their next labor, the women indicated a preference for early epidural.

CONCLUSION

Initiation of epidural analgesia in early labor, following the first request for epidural, did not result in increased cesarean deliveries, instrumental vaginal deliveries, and other adverse effects; furthermore, it was associated with shorter duration of the first stage of labor and was clearly preferred by the women.

The effects of continuous epidural analgesia on Doppler velocimetry of uterine arteries during different periods of labour analgesia

BACKGROUND

The transient effects of epidural bupivacaine 0.25-0.5% on the Doppler velocimetry of umbilical and uterine arteries had been reported, but the effects of continuous lower dose epidural bupivacaine (0.05-0.1%) infusion for labour analgesia have never been reported. In this study, we evaluated the effects of continuous epidural bupivacaine 0.075% on the Doppler velocimetry of uterine arteries.

METHODS

Twenty pregnant women for labour analgesia received continuous epidural bupivacaine 0.075% infusion. We used a 4-MHz continuous-wave Doppler probe (Multigon 500A) with a 200 Hz thump filter to detect uterine blood flow velocity. We recorded the velocimetry data for uterine relaxation and contraction during five time periods: pre-epidural insertion, 1, 2, and 4 h post-epidural infusion, and after delivery of fetus.

RESULTS

Our data showed that the velocimetric indices of uterine vascular resistance were significantly increased 1, 2, and 4 h after epidural infusion when compared with the pre-epidural level; these returned to the baseline after delivery.

CONCLUSION

Continuous epidural analgesia with bupivacaine 0.075% increases the resistance of uterine artery and therefore possibly reduces the uterine blood flow.

The risk of cesarean delivery with neuraxial analgesia given early versus late in labor

BACKGROUND

Epidural analgesia initiated early in labor (when the cervix is less than 4.0 cm dilated) has been associated with an increased risk of cesarean delivery. It is unclear, however, whether this increase in risk is due to the analgesia or is attributable to other factors.

METHODS

We conducted a randomized trial of 750 nulliparous women at term who were in spontaneous labor or had spontaneous rupture of the membranes and who had a cervical dilatation of less than 4.0 cm. Women were randomly assigned to receive intrathecal fentanyl or systemic hydromorphone at the first request for analgesia. Epidural analgesia was initiated in the intrathecal group at the second request for analgesia and in the systemic group at a cervical dilatation of 4.0 cm or greater or at the third request for analgesia. The primary outcome was the rate of cesarean delivery.

RESULTS

The rate of cesarean delivery was not significantly different between the groups (17.8 percent after intrathecal analgesia vs. 20.7 percent after systemic analgesia; 95 percent confidence interval for the difference, -9.0 to 3.0 percentage points; P=0.31). The median time from the initiation of analgesia to complete dilatation was significantly shorter after intrathecal analgesia than after systemic analgesia (295 minutes vs. 385 minutes, P<0.001), as was the time to vaginal delivery (398 minutes vs. 479 minutes, P<0.001). Pain scores after the first intervention were significantly lower after intrathecal analgesia than after systemic analgesia (2 vs. 6 on a 0-to-10 scale, P<0.001). The incidence of one-minute Apgar scores below 7 was significantly higher after systemic analgesia (24.0 percent vs. 16.7 percent, P=0.01).

CONCLUSIONS

Neuraxial analgesia in early labor did not increase the rate of cesarean delivery, and it provided better analgesia and resulted in a shorter duration of labor than systemic analgesia.

Induction of labor with oxytocin increases cesarean section rate as compared with oxytocin for augmentation of spontaneous labor in nulliparous parturients controlled for lumbar epidural analgesia

STUDY OBJECTIVES

To study labor outcomes in parturients receiving oxytocin for augmentation or induction of labor, in the presence of labor epidural analgesia.

DESIGN

Retrospective study of data from a continuous quality improvement database.

SETTING

Tertiary-care hospital with more than 8000 deliveries per annum.

MEASUREMENTS AND MAIN RESULTS

Of the 1671 healthy nulliparous women with singleton pregnancies and who requested labor epidural analgesia at our institution, 675 patients received oxytocin during elective induction of labor, whereas 996 patients received oxytocin for augmentation of spontaneous labor. Measured variables were cervical dilatation at time of epidural analgesia request, epidural insertion to 10-cm time, duration of stage 2 of labor, normal spontaneous vaginal delivery rate, cesarean section rate, operative vaginal delivery rate, and baby weight. Women admitted for induction of labor requested epidural analgesia sooner than those who had their labor augmented (p < 0.001). The incidence of cesarean section was higher in the induced group (p = 0.008).

CONCLUSION

Patients who have their labor induced request analgesia sooner and are at a higher risk of cesarean section than are patients who go into labor spontaneously. Any study that purports to assess the effects of epidural analgesia in labor should distinguish between induced and augmented/spontaneous labor.

Patient-controlled epidural technique improves analgesia for labor but increases cesarean delivery rate compared with the intermittent bolus technique

BACKGROUND

We tested the hypothesis that patient-controlled epidural analgesia for labor (PCEA) provides better analgesia and satisfaction than the intermittent bolus technique (bolus) without affecting the mode of delivery.

METHODS

We randomized 187 parturients to receive labor analgesia using either the PCEA or bolus technique. The PCEA group received a starting bolus of 14 mg of bupivacaine and 60 micro g of fentanyl in a 15-ml volume, followed by a background infusion (bupivacaine 0.08% and fentanyl 2 microg ml(-1)) 5 ml h(-1) with a 5-ml bolus and 15-min lock-out interval. The bolus group received boluses of 20 mg of bupivacaine and 75 micro g of fentanyl in a 15-ml volume.

RESULTS

Parturients in the PCEA group had significantly (P < 0.05-0.01) less pain during the first and second stages of labor. There was no difference in the spontaneous delivery rate between the groups, but the cesarean delivery rate was significantly (P < 0.05) higher (16.3% vs. 6.7%) in the PCEA group than in the bolus group. Bupivacaine consumption was significantly (P < 0.01) higher (11.2 mg h(-1) vs. 9.6 mg h(-1)) and the second stage of labor was significantly (P < 0.01) longer (70 min vs. 54 min) in the PCEA group than in the bolus group. Patient satisfaction was equally good in both groups.

CONCLUSION

The PCEA technique provided better pain relief. This was associated with higher bupivacaine consumption, prolongation of the second stage of labor, and an increased rate of cesarean section.

The effect of early epidural versus early intravenous analgesia use on labor progression: a natural experiment

OBJECTIVE

The purpose of this study was to compare the effect of early epidural with the use of early intravenous analgesia on labor progression.

STUDY DESIGN

We systematically selected singleton, nulliparous term pregnancies with a spontaneous labor and analgesia placement <or=4 cm who were delivered at a hospital where the rate of epidural analgesia in labor increased from 1% (before) to 84% (after) in 1 year (a natural experiment). In the before period (n=223 pregnancies), 98% of women used intravenous analgesia, and 2% of women used epidural analgesia. In the after period (n=278 pregnancies), 92% of women used epidural analgesia, and 8% of women used intravenous analgesia. The median duration of labor by each centimeter of cervical dilation was computed and used as a measurement of labor progression.

RESULTS

After adjustment had been made for confounders, women in the after period had a slower labor progression only from 4 to 5 cm, compared with those women in the before period. Interestingly, the process of labor admission and epidural analgesia placement, rather than analgesia use per se, appeared to explain most of the slowdown. No significant difference in the rest of the active phase was observed between the 2 groups.

CONCLUSION

Our data support recent American College of Obstetricians and Gynecologists guidelines that the restraining use of epidural analgesia at <4 cm of cervical dilation is unnecessary.

Epidural analgesia for pain relief in labour and childbirth - a review with a systematic approach

BACKGROUND

Clinical ambiguity concerning effects of epidural analgesia for pain relief in labour seems to reflect a need for evidence-based knowledge for midwives.

AIMS

This study aimed to review, with a systematic approach, the literature about effects and risks associated with the use of epidural analgesia for pain relief in labour and childbirth.

DESIGN

A structured question was formulated and used for deriving search terms, establishing the inclusion of certain criteria and retrieving articles, i.e. what are the effects of epidural analgesia for pain relief in labour and childbirth? References were obtained through searches using MeSH-terms in Medline and Subheadings (SH) in CINAHL (e.g. Obstetrical Analgesia combined either with psychology or adverse effects and together with, Dystocia, Caesarean Section, Infant Newborn and Breastfeeding). The articles were divided into prospective randomized trials (C), non-randomized prospective studies (P) and retrospective studies (R). Scientific quality of the studies was assessed on a three-grade scale: high scientific quality (I), moderate scientific quality (II) or low scientific quality (III).

RESULTS

Twenty-four articles were retrieved and systematically assessed. Seven studies were judged as high quality, 15 as moderate quality and two as low quality. The majority of studies appraised in this review failed to obtain or establish a cause and effect relationship. According to the data, it seems clear that the use of epidural analgesia is considered to be an effective method of pain relief during labour and childbirth from the perspective of women giving birth.

RELEVANCE TO CLINICAL PRACTICE

Midwives and doctors can recommend this form of pain relief. However, information about possible associations with adverse effects in mothers and infants must be provided to expectant couples.

Does the use of low dose bupivacaine/opioid epidural infusion increase the normal delivery rate?

To investigate whether using low dose epidural infusion improves the normal delivery rate, outcome of labour was studied in women with singleton vertex presentations randomised to receive either 0.0625% bupivacaine opioid, or plain bupivacaine 0.125% for labour. The infusion rate was titrated to maintain analgesia and a sensory level to T10. Data were analysed using the unpaired t test, Mann-Whitney U test and for categorical variables chi2 test. Adjusted odds ratios for factors significantly associated with non-normal delivery were calculated using stepwise logistic regression. There were 291 women in the low dose and 296 in the plain bupivacaine group. There were no significant differences between groups in parity, race, induction of labour, use of augmentation, cervical dilatation at epidural insertion, duration of any stage of labour or duration or volume of infusion. Total dose of bupivacaine (126 +/- 47 mg versus 91 +/- 32 mg) and the proportion of women with motor block at the end of labour (45% versus 27%) were significantly greater in the plain bupivacaine than in the low dose group (P < 0.0001). The adjusted odds ratios (95% CI) for factors significantly associated with non-normal delivery were primiparity: 4.68 (2.78-7.88), older maternal age: 1.1 (1.05-1.14), longer active second stage of labour: 1.01 (1.005-1.017), total bupivacaine dose: 1.01 (1.005-1.016) and greater cervical dilatation at epidural insertion 1.22 (1.08-1.37). Treatment group and motor block at the end of labour had no significant effect. We found no increase in normal delivery rate with low dose infusions.

The effect of epidural analgesia on postpartum urinary retention in women who deliver vaginally

There have been several investigations reporting on urinary retention in postpartum women who delivered vaginally with epidural blockade. The mechanism and incidence of urinary retention in relation to epidural analgesia, however, are not established. The objectives of this study were to investigate the association between various obstetric parameters and urinary retention and to determine whether those women with postpartum urinary retention subsequently develop urinary problems. From December 1999 to September 2000, 110 primiparas who delivered vaginally with epidural analgesia for labor pain relief were recruited prospectively. One hundred primiparas delivering under similar conditions without epidural analgesia were selected as the control group. Residual urine volume was calculated by trans-abdominal sonogram. A computerized obstetric database was analysed to compare the two groups. Women with epidural analgesia, especially those with residual volume exceeding 500 ml, had significantly longer labor course, a higher percentage of instrumental deliveries and more extensive vaginal or perineal lacerations than the control group. Only a few women had persistent problems with micturition six months after delivery. Epidural analgesia provides valuable pain relief but may be associated with greater residual urine. Postpartum urinary retention is, however, more related to prolonged labor than to the effect of epidural analgesia itself. Close monitoring of the progress of labor and avoiding urine retention are essential.

Analgesia and cesarean delivery rates

Various studies report conflicting data with regard to the level of risk of cesarean delivery for nulliparous women who receive epidural analgesia before 5 cm of cervical dilatation. As a result, some institutions are requiring that laboring women reach 4-5 cm of dilatation before receiving epidural analgesia. The American College of Obstetricians and Gynecologists wishes to reaffirm the opinion published jointly with the American Society of Anesthesiologists that while under a physician's care, in the absence of a medical contraindication, maternal request is a sufficient medical indication for pain relief during labor Decisions regarding analgesia should be coordinated among the obstetrician, the anesthesiologist, the patient, and support personnel.

Combined spinal-epidural analgesia for labor: breakthrough or unjustified invasion?

The combined spina-epidural (CSE) technique has become increasingly popular for labor analgesia. The advantages of the CSE include more rapid onset of analgesia, reduced total drug dosage, minimal or no motor blockade, and increased patient satisfaction. CSE has also been associated with more rapid cervical dilation when compared to epidural analgesia in nulliparous women in early labor. Despite these potential advantages, the indications for CSE versus epidural analgesia remain unclear and controversial. This review should allow better understanding of the benefits and risks of this technique, and bearing in mind that no ultimate neuraxial analgesic exists, it would seem that CSE should be considered a major breakthrough in the management of labor analgesia.

Continuous epidural analgesia with bupivacaine 0.125% or bupivacaine 0.0625% plus sufentanil 0.25 μg·mL−1: a study in singleton breech presentation

Epidural analgesia is the most efficient technique for labor pain relief. However, its resultant motor block might impair the mode of delivery, particularly in breech presentation where the risk of dystocia is high. In this trial, we compared bupivacaine 0.125% with a combination of a low concentration of bupivacaine (0.0625%) and sufentanil (0.25 microg.mL(-1)) both administered by continuous infusion. Analgesia, maternal and fetal/neonatal side effects and obstetric outcome were compared between group bupivacaine (n = 23) and group bupivacaine-sufentanil (n = 35). A greater number of patients in the bupivacaine 0.125% group required more than two top-ups (32 vs. 8% of patients, P = 0.03) while pain scores were similar. Motor block at delivery was more pronounced in the bupivacaine 0.125% group. Nausea and pruritus were more often encountered in the bupivacaine-sufentanil group. There was a trend toward a decreased rate of assisted or operative delivery in the bupivacaine-sufentanil group (92% vs. 74%, P = 0.09). Fetal/neonatal data did not differ between groups. Epidural analgesia with bupivacaine-sufentanil required fewer additional top-ups and produced less motor block than did bupivacaine 0.125%. However, there was no significant difference in mode of delivery between the two analgesic regimens.

Anesthesia and the progress of labour

CONCLUSIONS

The last decade has seen a remarkable advance in our understanding of the effects of regional analgesia on the progress and outcome of labour. In particular, the appearance of several well conducted prospective, randomized trials have helped confirm the opinion of most anesthesiologists and a growing number of obstetricians, that epidural analgesia only minimally lengthens labour and does not increase the risk of cesarean section. But the extraordinary methodological complexities of studying this unblindable treatment in patients who are anything but ambivalent about whether or not they receive it ensures the debate will continue. It is perhaps time to move away from outcome studies and on to investigations of the putative mechanisms of any effects epidural analgesia may have on the labour and delivery process. It is also vital to place greater emphasis on the interaction between obstetrical practice, analgesic technique, and the patient. There may be important differences between subsets of patients with regard to their risk of cesarean section and the effect epidural analgesia may have on this risk. This is almost certainly true for certain obstetrical practices. Only by an appreciation of the actual physiology of epidural analgesia in the context of obstetrical care and the labour process itself will one of the longest running debates in anesthesiology come to an end.

[The effects of peridural anesthesia on duration of labor and mode of delivery]

OBJECTIVE

To determine the effect of epidural analgesia (EA) on the duration of labour and the mode of delivery.

DATA SOURCES

A Medline computerised literature research was conducted from 1989 to 2000 including all the prospective studies comparing EA and systemic analgesia during labour.

DATA SYNTHESIS

EA prolongs the first and second stages of labour and increases the rate of instrumental delivery, without neonatal side effects. EA is not responsible for dystocia and caesarean section rate is not increased by this mode of analgesia. The effect of combined spinal-epidural analgesia is comparable to the one of EA on the length of labour and the mode of delivery. Ropivacaine does not appear to be different from bupivacaine in that setting. The benefit of ambulation remains controversial since it does not reduce the incidence of instrumental delivery, compared to conventional EA with similarly diluted local anaesthetic solutions.

CONCLUSIONS

Pain relief provided by EA combined to modification of obstetric management (amniotomy, oxytocin) does not impair the rate of caesarean section and dystocia.

Intravenous oxytocin alone for cervical ripening and induction of labour

BACKGROUND

Oxytocin is the commonest induction agent used worldwide. It has been used alone, in combination with amniotomy or following cervical ripening with other pharmacological or non-pharmacological methods. Prior to the introduction of prostaglandin agents oxytocin was used as a cervical ripening agent as well. In developed countries oxytocin alone is more commonly used in the presence of ruptured membranes whether spontaneous or artificial. In developing countries where the incidence of HIV is high, delaying amniotomy in labour reduces vertical transmission rates and hence the use of oxytocin with intact membranes warrants further investigation. This review will address the use of oxytocin alone for induction of labour. Amniotomy alone or oxytocin with amniotomy for induction of labour has been reviewed elsewhere in the Cochrane Library. Trials which consider concomitant administration of oxytocin and amniotomy will not be considered. This is one of a series of reviews of methods of cervical ripening and labour induction using a standardised methodology.

OBJECTIVES

To determine the effects of oxytocin alone for third trimester cervical ripening or induction of labour in comparison with other methods of induction of labour or placebo/no treatment.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group Trials Register, the Cochrane Controlled Trials Register and bibliographies of relevant papers. Last searched: May 2001.

SELECTION CRITERIA

The criteria for inclusion included the following: (1) clinical trials comparing vaginal prostaglandins used for third trimester cervical ripening or labour induction with placebo/no treatment or other methods listed above it on a predefined list of labour induction methods; (2) random allocation to the treatment or control group; (3) adequate allocation concealment; (4) violations of allocated management not sufficient to materially affect conclusions; (5) clinically meaningful outcome measures reported; (6) data available for analysis according to the random allocation; (7) missing data insufficient to materially affect the conclusions.

DATA COLLECTION AND ANALYSIS

A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction. The initial data extraction was done centrally, and incorporated into a series of primary reviews arranged by methods of induction of labour, following a standardised methodology. The data is to be extracted from the primary reviews into a series of secondary reviews, arranged by category of woman.

MAIN RESULTS

In total, 110 trials were considered; 52 have been excluded and 58 included examining a total of 11,129 women. Comparing oxytocin alone with expectant management: Oxytocin alone reduced the rate of unsuccessful vaginal delivery within 24 hours when compared with expectant management (8.3% versus 54%, relative risk (RR) 0.16, 95% confidence interval (CI) 0.10,0.25) but the caesarean section rate was increased (10.4% versus 8.9%, RR 1.17, 95% CI 1.01,1.36). This increase in caesarean section rate was not apparent in the subgroup analyses. Women were less likely to be unsatisfied with induction rather than expectant management, in the one trial reporting this outcome (5.5% versus 13.7%, RR 0.43, 95% CI 0.33, 0.56). Comparing oxytocin alone with vaginal prostaglandins: Oxytocin alone was associated with an increase in unsuccessful vaginal delivery within 24 hours (52% versus 28%, RR 1.85, 95% CI 1.41, 2.43), irrespective of membrane status, but there was no difference in caesarean section rates (11.4% versus 10%, RR 1.12, 95% CI 0.95, 1.33). Comparing oxytocin alone with intracervical prostaglandins: Oxytocin alone was associated with an increase in unsuccessful vaginal delivery within 24 hours when compared with intracervical PGE2 (51% versus 35%, RR 1.49, 95% CI 1.12,1.99). For all women with an unfavourable cervix regardless of membrane status, the caesarean section rates were increased (19.0% versus 13.1%, RR 1.42, 95% CI 1.11, 1.82).

REVIEWER'S CONCLUSIONS

Overall, comparison of oxytocin alone with either intravaginal or intracervical PGE2 reveals that the prostaglandin agents probably overall have more benefits than oxytocin alone. The amount of information relating to specific clinical subgroups is limited, especially with respect to women with intact membranes. Comparison of oxytocin alone to vaginal PGE2 in women with ruptured membranes reveals that both interventions are probably equally efficacious with each having some advantages and disadvantages over the others. With respect to current practice in women with ruptured membranes induction can be recommended by either method and in women with intact membranes there is insufficient information to make firm recommendations.