Intravenous fentanyl PCA during labour

Estimating the Complier Average Causal Effect in a Meta-Analysis of Randomized Clinical Trials With Binary Outcomes Accounting for Noncompliance: A Generalized Linear Latent and Mixed Model Approach

Noncompliance, a common problem in randomized clinical trials (RCTs), can bias estimation of the effect of treatment receipt using a standard intention-to-treat analysis. The complier average causal effect (CACE) measures the effect of an intervention in the latent subpopulation that would comply with their assigned treatment. Although several methods have been developed to estimate the CACE in analyzing a single RCT, methods for estimating the CACE in a meta-analysis of RCTs with noncompliance await further development. This article reviews the assumptions needed to estimate the CACE in a single RCT and proposes a frequentist alternative for estimating the CACE in a meta-analysis, using a generalized linear latent and mixed model with SAS software (SAS Institute, Inc.). The method accounts for between-study heterogeneity using random effects. We implement the methods and describe an illustrative example of a meta-analysis of 10 RCTs evaluating the effect of receiving epidural analgesia in labor on cesarean delivery, where noncompliance varies dramatically between studies. Simulation studies are used to evaluate the performance of the proposed method.

A Bayesian hierarchical model estimating CACE in meta-analysis of randomized clinical trials with noncompliance

Noncompliance to assigned treatment is a common challenge in analysis and interpretation of randomized clinical trials. The complier average causal effect (CACE) approach provides a useful tool for addressing noncompliance, where CACE is defined as the average difference in potential outcomes for the response in the subpopulation of subjects who comply with their assigned treatments. In this article, we present a Bayesian hierarchical model to estimate the CACE in a meta-analysis of randomized clinical trials where compliance may be heterogeneous between studies. Between-study heterogeneity is taken into account with study-specific random effects. The results are illustrated by a re-analysis of a meta-analysis comparing the effect of epidural analgesia in labor versus no or other analgesia in labor on the outcome cesarean section, where noncompliance varied between studies. Finally, we present simulations evaluating the performance of the proposed approach and illustrate the importance of including appropriate random effects and the impact of over- and under-fitting.

Epidural versus non-epidural or no analgesia for pain management in labour

BACKGROUND

Epidural analgesia is a central nerve block technique achieved by injection of a local anaesthetic close to the nerves that transmit pain, and is widely used as a form of pain relief in labour. However, there are concerns about unintended adverse effects on the mother and infant. This is an update of an existing Cochrane Review (Epidural versus non-epidural or no analgesia in labour), last published in 2011.

OBJECTIVES

To assess the effectiveness and safety of all types of epidural analgesia, including combined-spinal-epidural (CSE) on the mother and the baby, when compared with non-epidural or no pain relief during labour.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (ClinicalTrials.gov), the WHO International Clinical Trials Registry Platform (ICTRP) (30 April 2017), and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials comparing all types of epidural with any form of pain relief not involving regional blockade, or no pain relief in labour. We have not included cluster-randomised or quasi-randomised trials in this update.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risks of bias, extracted data and checked them for accuracy. We assessed selected outcomes using the GRADE approach.

MAIN RESULTS

Fifty-two trials met the inclusion criteria and we have included data from 40 trials, involving over 11,000 women. Four trials included more than two arms. Thirty-four trials compared epidural with opioids, seven compared epidural with no analgesia, one trial compared epidural with acu-stimulation, one trial compared epidural with inhaled analgesia, and one trial compared epidural with continuous midwifery support and other analgesia. Risks of bias varied throughout the included studies; six out of 40 studies were at high or unclear risk of bias for every bias domain, while most studies were at high or unclear risk of detection bias. Quality of the evidence assessed using GRADE ranged from moderate to low quality.Pain intensity as measured using pain scores was lower in women with epidural analgesia when compared to women who received opioids (standardised mean difference -2.64, 95% confidence interval (CI) -4.56 to -0.73; 1133 women; studies = 5; I2 = 98%; low-quality evidence) and a higher proportion were satisfied with their pain relief, reporting it to be "excellent or very good" (average risk ratio (RR) 1.47, 95% CI 1.03 to 2.08; 1911 women; studies = 7; I2 = 97%; low-quality evidence). There was substantial statistical heterogeneity in both these outcomes. There was a substantial decrease in the need for additional pain relief in women receiving epidural analgesia compared with opioid analgesia (average RR 0.10, 95% CI 0.04 to 0.25; 5099 women; studies = 16; I2 = 73%; Tau2 = 1.89; Chi2 = 52.07 (P < 0.00001)). More women in the epidural group experienced assisted vaginal birth (RR 1.44, 95% CI 1.29 to 1.60; 9948 women; studies = 30; low-quality evidence). A post hoc subgroup analysis of trials conducted after 2005 showed that this effect is negated when trials before 2005 are excluded from this analysis (RR 1.19, 95% CI 0.97 to 1.46). There was no difference between caesarean section rates (RR 1.07, 95% CI 0.96 to 1.18; 10,350 women; studies = 33; moderate-quality evidence), and maternal long-term backache (RR 1.00, 95% CI 0.89 to 1.12; 814 women; studies = 2; moderate-quality evidence). There were also no clear differences between groups for the neonatal outcomes, admission to neonatal intensive care unit (RR 1.03, 95% CI 0.95 to 1.12; 4488 babies; studies = 8; moderate-quality evidence) and Apgar score less than seven at five minutes (RR 0.73, 95% CI 0.52 to 1.02; 8752 babies; studies = 22; low-quality evidence). We downgraded the evidence for study design limitations, inconsistency, imprecision in effect estimates, and possible publication bias.Side effects were reported in both epidural and opioid groups. Women with epidural experienced more hypotension, motor blockade, fever, and urinary retention. They also had longer first and second stages of labour, and were more likely to have oxytocin augmentation than the women in the opioid group. Women receiving epidurals had less risk of respiratory depression requiring oxygen, and were less likely to experience nausea and vomiting than women receiving opioids. Babies born to women in the epidural group were less likely to have received naloxone. There was no clear difference between groups for postnatal depression, headache, itching, shivering, or drowsiness. Maternal morbidity and long-term neonatal outcomes were not reported.Epidural analgesia resulted in less reported pain when compared with placebo or no treatment, and with acu-stimulation. Pain intensity was not reported in the trials that compared epidural with inhaled analgesia, or continuous support. Few trials reported on serious maternal side effects.

AUTHORS' CONCLUSIONS

Low-quality evidence shows that epidural analgesia may be more effective in reducing pain during labour and increasing maternal satisfaction with pain relief than non-epidural methods. Although overall there appears to be an increase in assisted vaginal birth when women have epidural analgesia, a post hoc subgroup analysis showed this effect is not seen in recent studies (after 2005), suggesting that modern approaches to epidural analgesia in labour do not affect this outcome. Epidural analgesia had no impact on the risk of caesarean section or long-term backache, and did not appear to have an immediate effect on neonatal status as determined by Apgar scores or in admissions to neonatal intensive care. Further research may be helpful to evaluate rare but potentially severe adverse effects of epidural analgesia and non-epidural analgesia on women in labour and long-term neonatal outcomes.

Non-Neuraxial Labor Analgesia: Options

Although it is the most effective method to treat labor pain, neuraxial analgesia may be undesired, contraindicated, unsuccessful, or unavailable. Providing safe choices for labor pain relief is a central goal of health care providers alike. Consequently, knowledge of the efficacy, clinical implementation, and side effects of various non-neuraxial strategies is needed to provide appropriate options for laboring patients. In addition to nonpharmacologic alternatives, inhaled nitrous oxide and systemic opioids represent two broad classes of non-neuraxial pharmacologic labor analgesia most commonly available. This review summarizes the current published literature for these non-neuraxial labor analgesic options.

Continuous Epidural Analgesia Using an Ester-Linked Local Anesthetic Agent, 2-Chloroprocaine, During Labor: A Case Report

We report the use of the ester-linked local anesthetic, 2-chloroprocaine, for continuous epidural analgesia in a patient in labor with a history of allergic reaction to amide local anesthetics. The patient gave a reliable history of pruritus, hives, erythema, and swelling on her lower extremity after having received a preservative-free amide local anesthetic. This allergy had been confirmed by a dermatologist by her reports. The patient requested an epidural for labor analgesia that was placed successfully. After an initial bolus, a continuous infusion of 1.5% of 2-chloroprocaine was initiated to achieve satisfactory pain relief throughout an uneventful vaginal delivery.

Adjustment for compliance behavior in trials of epidural analgesia in labor using instrumental variable meta-analysis

OBJECTIVES

Intention-to-treat (ITT) analysis of randomized controlled trials (RCTs) may cause bias when compliance is poor. Noncompliance describes failure to comply with allocation in the intervention arm, and contamination describes uptake of the intervention in the control arm. Instrumental variable (IV) analysis can be applied in addition to the primary ITT analysis to estimate the causal effect adjusted for noncompliance and contamination, assuming that noncompliers would have had the same treatment benefit as compliers. We aimed to compare ITT and IV meta-analysis of the association between epidural analgesia in labor and cesarean section.

STUDY DESIGN AND SETTING

The study was restricted to 27 trials in a Cochrane Systematic Review. The association between epidural analgesia in labor and cesarean section was calculated using ITT and IV analyses. Pooled risk ratios (RRs) were calculated using fixed-effects meta-analysis.

RESULTS

In 18 trials with compliance data, noncompliance was 23% and contamination was 27%. In 10 trials with outcome data stratified by compliance, the pooled RR for cesarean section following epidural analgesia was 1.37 [95% confidence interval (CI): 1.00, 1.89; P = 0.049] using IV compared with 1.19 (95% CI: 0.93, 1.51; P = 0.16) using ITT.

CONCLUSION

ITT meta-analysis underestimates the effect of receiving epidural analgesia in labor on cesarean section compared with IV meta-analysis.

The effect of intravenous fentanyl on pain and duration of the active phase of first stage labor

OBJECTIVES

Opioids are most widely used for pain relief during childbirth. An alternative opioid, fentanyl, has been shown to be a good option for pain management and has fewer side-effects on both mother and fetus. Therefore, the purpose of this study is to determine the effect of fentanyl on pain as well as the duration of the active phase of labor.

METHODS

This clinical trial was conducted on 70 multiparous parturients having labor from May to July 2006 at Tamin Ejtemai Hospital. They were selected by convenience sampling at the beginning of the active phase of labor. The samples were then randomly divided into the case and control groups. The case group received fentanyl 50 micrograms in two doses, one hour apart after being diluted (0 and 60 mins). Vital signs were recorded pre-administration and 5, 15, 30, 45, 60 minutes post-administration. Pain intensity was estimated by visual pain scale (0-10) four times (before and 1, 2, 3 hours after the intervention). Data analysis was done using the student t-test, repeated measure ANOVA and chi-square tests via SPSS 11.5 software.

RESULTS

The results showed a significant reduction in pain (p=0.002) and HR (p=0.001) in the case group. The mean pain score also decreased from 8±1 to 5±1. There was a significant difference in terms of the duration of the active phase between the two groups (p=0.001). However, there were no significant differences in terms of systolic blood pressure and diastolic blood pressure between the two groups.

CONCLUSION

Fentanyl provides good analgesic effect for pain management during labor by considerably reducing the duration of the active phase, and can therefore be used as an acceptable analgesic agent during labor.

Epidural versus non-epidural or no analgesia in labour

BACKGROUND

Epidural analgesia is a central nerve block technique achieved by injection of a local anaesthetic close to the nerves that transmit pain and is widely used as a form of pain relief in labour. However, there are concerns regarding unintended adverse effects on the mother and infant.

OBJECTIVES

To assess the effects of all modalities of epidural analgesia (including combined-spinal-epidural) on the mother and the baby, when compared with non-epidural or no pain relief during labour.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 March 2011).

SELECTION CRITERIA

Randomised controlled trials comparing all modalities of epidural with any form of pain relief not involving regional blockade, or no pain relief in labour.

DATA COLLECTION AND ANALYSIS

Two of the review authors independently assessed trials for eligibility, methodological quality and extracted all data. We entered data into RevMan and double checked it for accuracy. Primary analysis was by intention to treat; we conducted subgroup and sensitivity analyses where substantial heterogeneity was evident.

MAIN RESULTS

We included 38 studies involving 9658 women; all but five studies compared epidural analgesia with opiates. Epidural analgesia was found to offer better pain relief (mean difference (MD) -3.36, 95% confidence interval (CI) -5.41 to -1.31, three trials, 1166 women); a reduction in the need for additional pain relief (risk ratio (RR) 0.05, 95% CI 0.02 to 0.17, 15 trials, 6019 women); a reduced risk of acidosis (RR 0.80, 95% CI 0.68 to 0.94, seven trials, 3643 women); and a reduced risk of naloxone administration (RR 0.15, 95% CI 0.10 to 0.23, 10 trials, 2645 women). However, epidural analgesia was associated with an increased risk of assisted vaginal birth (RR 1.42, 95% CI 1.28 to 1.57, 23 trials, 7935 women), maternal hypotension (RR 18.23, 95% CI 5.09 to 65.35, eight trials, 2789 women), motor-blockade (RR 31.67, 95% CI 4.33 to 231.51, three trials, 322 women), maternal fever (RR 3.34, 95% CI 2.63 to 4.23, six trials, 2741 women), urinary retention (RR 17.05, 95% CI 4.82 to 60.39, three trials, 283 women), longer second stage of labour (MD 13.66 minutes, 95% CI 6.67 to 20.66, 13 trials, 4233 women), oxytocin administration (RR 1.19, 95% CI 1.03 to 1.39, 13 trials, 5815 women) and an increased risk of caesarean section for fetal distress (RR 1.43, 95% CI 1.03 to 1.97, 11 trials, 4816 women). There was no evidence of a significant difference in the risk of caesarean section overall (RR 1.10, 95% CI 0.97 to 1.25, 27 trials, 8417 women), long-term backache (RR 0.96, 95% CI 0.86 to 1.07, three trials, 1806 women), Apgar score less than seven at five minutes (RR 0.80, 95% CI 0.54 to 1.20, 18 trials, 6898 women), and maternal satisfaction with pain relief (RR 1.31, 95% CI 0.84 to 2.05, seven trials, 2929 women). We found substantial heterogeneity for the following outcomes: pain relief; maternal satisfaction; need for additional means of pain relief; length of second stage of labour; and oxytocin augmentation. This could not be explained by subgroup or sensitivity analyses, where data allowed analysis. No studies reported on rare but potentially serious adverse effects of epidural analgesia.

AUTHORS' CONCLUSIONS

Epidural analgesia appears to be effective in reducing pain during labour. However, women who use this form of pain relief are at increased risk of having an instrumental delivery. Epidural analgesia had no statistically significant impact on the risk of caesarean section, maternal satisfaction with pain relief and long-term backache and did not appear to have an immediate effect on neonatal status as determined by Apgar scores. Further research may be helpful to evaluate rare but potentially severe adverse effects of epidural analgesia on women in labour and long-term neonatal outcomes.

Retrospective evaluation of intravenous fentanyl patient-controlled analgesia during labor

PURPOSE

Because the safety of intravenous fentanyl patient-controlled analgesia (iv-PCA) administered during labor remains unclear, we retrospectively examined the labor records from January 2005 to December 2007 in our institution, with a focus on both maternal and neonatal outcomes, as compared to no analgesia.

METHODS

Parturients over 35 weeks of gestational age who received fentanyl iv-PCA (iv-PCA group) or no analgesia (control group) during labor were enrolled. The former group received iv-PCA through a pump programmed to give a loading dose of 0.05 mg fentanyl, followed by bolus injection of 0.02 mg fentanyl, with a lock-out interval of 5 min. This analgesia was initiated at the parturient's request and was discontinued before the second stage of labor, to ensure neonatal safety. During labor, both maternal and fetal heart rates, maternal pulse oximeter oxygen saturation (SpO(2)), respiratory rate, and sedation and nausea scores were continuously monitored, and the neonatal outcomes including umbilical arterial pH, Apgar scores, and other parameters were recorded.

RESULTS

The data of 129 of the 143 parturients who received fentanyl iv-PCA were analyzed, while 697 parturients delivered without any analgesia during the 3-year study period. While iv-PCA prolonged the duration of labor and increased oxytocin use, no obvious maternal or neonatal complications of fentanyl use were recorded. Except for the significantly lower rate of emergency cesarean section in the iv-PCA group, both the maternal and neonatal outcomes were comparable between the groups.

CONCLUSIONS

As compared to no analgesia, fentanyl iv-PCA appears to be safe and clinically acceptable as analgesia during labor, particularly in nulliparous women.

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.

Fetal acidosis from obstetric interventions during the first vaginal delivery

OBJECTIVE

The aim of this study was to analyze the blood gas values of umbilical cord blood in newborns of first vaginal deliveries with or without obstetric interventions.

MATERIALS AND METHODS

In a prospective descriptive study conducted during the 6-month period from August 2003 through February 2004 at a university hospital, we analyzed the umbilical cord blood gas results of 80 term newborns delivered vaginally from healthy nulliparous women. Multivariate logistic analysis was used to evaluate the associations between fetal acidosis (pH<7.20) and any obstetric interventions.

RESULTS

The mean of umbilical cord blood arterial pH was 7.26 (standard deviation, 0.072). After controlling for the confounding factors with multivariate logistic regression, fetal acidosis (pH<7.20) was found to be significantly associated with oxytocin augmentation (odds ratio [OR], 16.48; 95% confidence interval [CI], 1.21-226.1) and vacuum extraction (OR, 10.76; 95% CI, 1.025-112.9). In contrast, there was no significant relationship between fetal acidosis with episiotomy (OR, 1.096; 95% CI, 0.07-16.6) or epidural anesthesia (OR, 0.074; 95% CI, 0.003-2.09).

CONCLUSION

Oxytocin augmentation and vacuum extraction were significantly related to low cord arterial pH values (pH<7.20), but there were no adverse effects to the newborns of first vaginal deliveries.

Options for systemic labor analgesia

PURPOSE OF REVIEW

This article reviews the challenging practice of systemic analgesia as an alternative to epidural analgesia for labor pain, and places remifentanil within the context of opioid analgesics suitable for managing for labor pain.

RECENT FINDINGS

Although systemic opioids have long been used for labor analgesia, they have become less popular because of frequent maternal and neonatal side effects. Recently, their efficacy has been questioned. Patient-controlled intravenous analgesia with fentanyl or sufentanil is currently the method of choice for achieving analgesia during early labor, when epidural analgesia is not feasible. Remifentanil has been suggested as the opioid of choice for labor analgesia, having the advantage of easy administration, predictable pharmacokinetics, and improved neonatal outcomes. The position of remifentanil in obstetric analgesia is now better understood, as reflected by the increasing number of reported studies describing its use.

SUMMARY

Remifentanil is now gaining popularity. Remifentanil may be more suitable than other traditional opioids for inducing labor analgesia. Careful monitoring of the parturient and the newborn is recommended, however, to mitigate the potential for maternal and neonatal hypoxemia.

Use of epidural analgesia and its relation to caesarean and instrumental deliveries—a population-based study of 94,217 primiparae

OBJECTIVES

To investigate the association between epidural analgesia for labour-pain relief and mode of delivery.

STUDY DESIGN

The Swedish medical birth register covers 99% of all births and contains prospectively collected information from all delivery units in Sweden. The present population-based cohort study includes singleton births among nulliparae during 1998-2000, excluding deliveries with elective caesarean section, giving study population of n=94,217. The frequencies of epidural block in this population were estimated for each delivery unit. The outcomes studied were non-elective caesarean section and instrumental delivery.

RESULTS

There was no clear association between frequency of epidural block and caesarean section and instrumental delivery, respectively. Delivery units with the lowest (20-29%) and the highest (60-64%) relative frequencies of epidural block had the lowest proportion of caesarean section (9.1%). For the other groups the proportion varied between 10.3 and 10.6%. Instrumental deliveries were most common, 18.8%, in delivery units with 50-59% frequency of epidural block use. The lowest incidence (14.1%) was in units using epidurals in 30-39% of cases. In the other groups (20-29, 40-49 and 60-64%) the proportion varied between 15.3 and 15.7%.

CONCLUSIONS

This investigation shows no clear association between epidural use and caesarean section or instrumental delivery, indicating that there is no reason to restrict the epidural rate to improve obstetric outcome.

Epidural versus non-epidural or no analgesia in labour

BACKGROUND

Epidural analgesia is a central nerve block technique achieved by injection of a local anaesthetic close to the nerves that transmit pain and is widely used as a form of pain relief in labour. However, there are concerns regarding unintended adverse effects on the mother and infant.

OBJECTIVES

To assess the effects of all modalities of epidural analgesia (including combined -spinal-epidural) on the mother and the baby, when compared with non-epidural or no pain relief during labour.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (June 2005).

SELECTION CRITERIA

Randomised controlled trials comparing all modalities of epidural with any form of pain relief not involving regional blockade, or no pain relief in labour.

DATA COLLECTION AND ANALYSIS

Two of the review authors independently assessed trials for eligibility, methodological quality and extracted all data. Data were entered into RevMan and double checked. Primary analysis was by intention-to-treat; sensitivity analyses excluded trials with > 30% of women receiving un-allocated treatment.

MAIN RESULTS

Twenty-one studies involving 6664 women were included, all but one study compared epidural analgesia with opiates. For technical reasons, data on women's perception of pain relief in labour could only be included from one study which found epidural analgesia to offer better pain relief than non-epidural analgesia (weighted mean difference (WMD) -2.60, 95% confidence interval (CI) -3.82 to -1.38, 1 trial, 105 women). However, epidural analgesia was associated with an increased risk of instrumental vaginal birth (relative risk (RR) 1.38, 95% CI 1.24 to 1.53, 17 trials, 6162 women). There was no evidence of a significant difference in the risk of caesarean delivery (RR 1.07, 95% CI 0.93 to 1.23, 20 trials, 6534 women), long-term backache (RR 1.00, 95% CI 0.89 to 1.12, 2 trials, 814 women), low neonatal Apgar scores at five minutes (RR 0.70, 95% CI 0.44 to 1.10, 14 trials, 5363 women), and maternal satisfaction with pain relief (RR 1.18 95% CI 0.92 to 1.50, 5 trials, 1940 women). No studies reported on rare but potentially serious adverse effects of epidural analgesia.

AUTHORS' CONCLUSIONS

Epidural analgesia appears to be effective in reducing pain during labour. However, women who use this form of pain relief are at increased risk of having an instrumental delivery. Epidural analgesia had no statistically significant impact on the risk of caesarean section, maternal satisfaction with pain relief and long-term backache and did not appear to have an immediate effect on neonatal status as determined by Apgar scores. Further research may be helpful to evaluate rare but potentially severe adverse effects of epidural analgesia on women in labour and long-term neonatal outcomes.

Analgesia and Anesthesia in Labor

Whether given as an epidural, spinal, or combination, regional anesthesia is an integral part of obstetrics in the United States. A variety of drugs and dosages are used in various combinations, with no one protocol exceeding others in terms of efficacy and safety. The availability of anesthesia and analgesia has had an extraordinary impact on the field of obstetrics in the twentieth century. Knowledge of the techniques and medications used, their potential toxicities, and effects on the labor process itself can only enhance obstetricians' management of the parturient in labor.

A Multicenter Randomized Controlled Trial Comparing Patient-Controlled Epidural with Intravenous Analgesia for Pain Relief in Labor

In this multicenter, randomized, controlled trial, we sought to determine whether patient-controlled epidural analgesia (PCEA) for labor affected the incidence of cesarean delivery when compared with patient-controlled IV opioid analgesia (PCIA). Healthy, term nulliparous patients in 4 Canadian institutions were randomly assigned to receive PCIA with fentanyl (n = 118) or PCEA with 0.08% bupivacaine and fentanyl 1.6 microg/mL (n = 124). There was no difference in the incidence of cesarean delivery-10.2% (12 of 118) versus 9.7% (12 of 124)-or instrumental vaginal delivery-21.2% (25 of 118) versus 29% (36 of 124)-between groups. The duration of the second stage of labor was increased in the PCEA group by a median of 23 min (P = 0.02). Fifty-one patients (43%) in the PCIA group received epidural analgesia: 39 (33%) because of inadequate pain relief and 12 (10%) to facilitate operative delivery. Patients in the PCIA group required more antiemetic therapy (17% versus 6.4%; P = 0.01) and had more sedation (39% versus 5%; P < 0.001). Maternal mean pain and satisfaction with analgesia scores were better in the PCEA group (P < 0.001 and P = 0.02, respectively). More neonates in the PCIA group required active resuscitation (52% versus 31%; P = 0.001) and naloxone (17% versus 3%; P < 0.001). These observations support the hypothesis that PCEA does not result in an increased incidence of obstetrical intervention compared with PCIA. PCEA provides superior analgesia and less maternal and neonatal sedation compared with PCIA.

Rates of caesarean section and instrumental vaginal delivery in nulliparous women after low concentration epidural infusions or opioid analgesia: systematic review

OBJECTIVE

To compare the effects of low concentration epidural infusions of bupivacaine with parenteral opioid analgesia on rates of caesarean section and instrumental vaginal delivery in nulliparous women.

DATA SOURCES

Medline, Embase, the Cochrane controlled trials register, and handsearching of the International Journal of Obstetric Anesthesia.

STUDY SELECTION

Randomised controlled trials comparing low concentration epidural infusions with parenteral opioids.

DATA SYNTHESIS

Seven trials fulfilled the inclusion criteria for meta-analysis. Epidural analgesia does not seem to be associated with an increased risk of caesarean section (odds ratio 1.03, 95% confidence interval 0.71 to 1.48) but may be associated with an increased risk of instrumental vaginal delivery (2.11, 0.95 to 4.65). Epidural analgesia was associated with a longer second stage of labour (weighted mean difference 15.2 minutes, 2.1 to 28.2 minutes). More women randomised to receive epidural analgesia had adequate pain relief, with fewer changing to parenteral opioids than vice versa (odds ratio 0.1, 0.05 to 0.22).

CONCLUSIONS

Epidural analgesia using low concentration infusions of bupivacaine is unlikely to increase the risk of caesarean section but may increase the risk of instrumental vaginal delivery. Although women receiving epidural analgesia had a longer second stage of labour, they had better pain relief.

Patient-controlled analgesia with fentanyl provides effective analgesia for second trimester labour: a randomized controlled study

PURPOSE

To examine dose and lockout intervals for effective fentanyl patient-controlled analgesia (PCA) in second trimester genetic termination of pregnancy, and compare three different fentanyl PCA regimes with morphine PCA.

METHODS

In a double-blind randomized study, 60 ASA physical status I-II patients received one of three fentanyl PCAs or morphine PCA. Labour was induced with prostaglandins and PCA use continued until delivery. Within two hours following delivery, four visual analogue scales (VAS) were administered measuring anticipated pain, pain relief in labour and delivery, and overall satisfaction. The drug delivery/demand ratio for two hours preceding delivery was obtained from the PCA pump. The outcome variables were analyzed using the Chi square test and analysis of variance as appropriate.

RESULTS

The delivery/demand ratio was 0.71 +/- 0.27 (mean +/- standard deviation) for morphine; 0.67 +/- 0.21 for fentanyl 50 micro g, lockout six-minute; 0.63 +/- 0.21 for fentanyl 25 micro g, lockout three-minute; and 0.81 +/- 0.17 for fentanyl 50 micro g, lockout three-minute groups. We found no significant differences among the four groups with respect to using delivery/demand ratio as a measure of pain relief. Morphine had the highest rate of side effects compared to fentanyl. There was strong evidence of differences among groups with regard to patient satisfaction and expected pain, and moderate evidence of differences in the delivery and labour pain scores.

CONCLUSION

This study found PCA fentanyl 50 micro g with a lockout period of six minutes provided satisfactory analgesia for second trimester labour.

Effects of obstetric analgesics and anesthetics on the neonate : a review

Most anesthetic and analgesic agents in current use traverse the placental barrier in varying degrees, but are well tolerated by the fetus if judiciously administered. For labor analgesia, many options are available. Systemic administration of opioids and sedatives is one such option. Repeated maternal administration of opioids such as pethidine (meperidine) results in significant fetal exposure and neonatal respiratory depression. Patient-controlled analgesia with synthetic opioids such as fentanyl, alfentanil, and the new ultra-short-acting remifentanil may be used for labor analgesia in selected patients. Other options for labor analgesia include epidural and combined spinal-epidural techniques. With such techniques, neonatal exposure to opioids and sedatives can be minimized or totally avoided. While limiting the fetal exposure to the harmful effects of depressant drugs, epidural anesthesia and/or analgesia improves placental perfusion and oxygenation of the fetus, which is beneficial, especially in conditions such as pregnancy-induced hypertension. Regional blocks are also administered for the majority of cesarean deliveries because of the overwhelming and unequivocal evidence of maternal and fetal safety compared with general anesthesia for this indication. However, in some instances, administration of general anesthesia is unavoidable. Neonatal respiratory depression with low Apgar scores, and umbilical arterial and venous pH associated with general anesthesia, is often transient. A properly administered anesthetic, whether regional or general, has no significant adverse fetal or neonatal effects.

Newer techniques of labor analgesia

In maternity units in which central neuraxial techniques are frequently used, newer methods of epidural drug delivery (continuous infusion, patient-controlled) are well established and combined spinal-epidural analgesia is commonly used. Continuous spinal analgesia has reemerged as a useful approach after accidental dural puncture. Lumbar sympathetic block has been revisited and the safety of paracervical nerve block improved. The analgesic properties of systemic opioid in labor are poor, but PCIA at least has psychological benefits and allows rapid drug titration. PCIA is again under investigation because of the potent antinociceptive effects of the short-acting mu-opioid agonist, remifentanil. The premixing of nitrous oxide and a subanesthetic concentration of volatile anesthetic for patient-controlled administration has been tested under control of midwifery staff and without direct medical supervision.

Misconceptions about neuraxial analgesia

Neuraxial analgesia is the most effective treatment for labor pain. Although there are known risks and side effects, many problems are attributed to the technique without appropriate scientific assessment. Some observations, such as the increased use of forceps and prolonged second stage of labor, are associated with epidural analgesia, but there is not enough evidence to categorically state whether the technique caused the problems. These topics warrant continued investigation.

A comparison of pethidine and remifentanil patient-controlled analgesia in labour

We conducted a double-blind randomised controlled trial comparing the efficacy of analgesia during labour of remifentanil and pethidine. Nine women were randomised to receive an i.v. bolus of remifentanil 0.5 microg.kg(-1)with a lockout period of 2 min and eight women were randomised to receive a bolus of pethidine 10 mg with a lockout period of 5 min. A visual analogue scale (VAS) scoring system was used to assess the level of pain hourly throughout the first and second stages of labour and a score was recorded within half an hour of delivery for the level of pain overall throughout labour (post delivery score). The study was terminated after 17 subjects, on agreement with the local ethics committee, due to concern with the poor Apgar scores in the pethidine group. With the data available, we demonstrated significantly lower mean hourly and post delivery VAS scores for pain in the remifentanil group (P < 0.05). The 1 and 5 min Apgar scores were significantly lower in the pethidine group compared with the remifentanil group (P < 0.05). This preliminary study suggests that remifentanil may have a use as patient-controlled analgesia for women in labour.

Patient-controlled intravenous analgesia using remifentanil in the parturient

PURPOSE

To show the use of the short acting opioid remifentanil for labour analgesia when epidural analgesia is considered to be contraindicated.

CLINICAL FEATURES

After Ethics Committee approval and informed consent, six patients (36-40 wk gestation), in whom epidural analgesia was considered contraindicated (women refusing regional analgesia, presenting with coagulation or platelet abnormalities or sepsis) benefited from patient-controlled intravenous analgesia (PCIA) with remifentanil. The Abbott Lifecare patient-controlled analgesia (PCA) pump with remifentanil 50 microg x ml(-1) was set to deliver remifentanil continuous background infusion of 0.05 microg x kg(-1) x min(-1) and 25 microg boluses with a five minutes lockout period. The PCIA was started when the parturients experienced regular painful contractions (cervical dilatation of at least 4 cm) and stopped just before delivery (cervix fully dilated). Maternal monitoring included non-invasive blood pressure measurements, heart rate, percutaneous arterial oxyhemoglobin saturation and respiratory rate. Percutaneous fetal heart rate was continuously monitored. All patients remained alert or sleepy but easily arousable and were satisfied with their analgesia. No particular side effects have been noticed. Apgar scores were between 6 and 10.

CONCLUSION

Remifentanil PCIA combining low continuous background infusion and small bolus doses is an alternative when epidural analgesia in labour is contraindicated. Under careful anesthesia monitoring, the technique seems to be safe for both mother and baby, at least when delivery occurs at or near the normal term of pregnancy.