An Association Between Severe Labor Pain and Cesarean Delivery

Analgesic considerations for induction of labor

Induction of labor may be indicated to minimize maternal and fetal risks. The rate of induction is likely to increase as recent evidence supports elective induction at 39 weeks gestation. We review methods of induction and then analgesic options as they relate to indications and methods to induce labor. We specifically focus on parturients at high risk for anesthetic complications including those requiring anticoagulation, and those with cardiac disease, obesity, chorioamnionitis, prior spinal instrumentation, elevated intracranial pressure, known or anticipated difficult airway, thrombocytopenia, and preeclampsia. Guidelines regarding timing of anticoagulation dosing with neuraxial anesthetic techniques have been defined through consensus statements. Early epidural placement may be beneficial in patients with cardiac disease, obesity, anticipated difficult airway, and HELLP syndrome. Questions remain regarding how early is too early for epidural placement, what options are safest for patients with bacteremia, and what pain relief should be offered to those unable to tolerate cervical exams in early labor.

Association of Pain Catastrophizing with Postnatal Depressive States in Nulliparous Parturients: A Prospective Study

PURPOSE

Postnatal depression (PND) is associated with maternal morbidity and socioeconomic burden. Recent studies have shown an association between pain catastrophizing, increased labor pain, and subsequent adverse postnatal adjustment; however, little is known on its role in PND development. We aimed to investigate the association between pain catastrophizing and probable PND.

METHODS

Parturients planning to undergo epidural labor analgesia were recruited. Predelivery questionnaires, including the Pain Catastrophizing Scale (PCS) and Edinburgh Postnatal Depression Scale (EPDS), were administered during early labor. A phone survey at 5- 9 weeks postdelivery was conducted to determine postdelivery EPDS and Spielberger's State-Trait-Anxiety Inventory scores. The primary outcome was a binary variable of postdelivery EPDS with cutoff of ≥10, whereas the secondary outcome was a continuous variable on increases in EPDS score.

RESULTS

Probable PND (EPDS ≥10) occurred in 10.5% (95% CI 8.0%-13.5%, 55 of 525) of women who underwent epidural labor analgesia. We found that high pain catastrophizing (PCS ≥25) was associated with increased postdelivery EPDS scores (adjusted β estimate 0.36, 95% CI 0.15-0.57; p=0.0008), but did not meet significance for increased risk of probable PND (p=0.1770). Additionally, presence of breakthrough pain during epidural analgesia (adjusted β estimate 0.24, 95% CI 0.02-0.46; p=0.0306) and lower BMI at term (adjusted β estimate -0.04, 95% CI -0.07 to -0.01; p=0.0055) were associated with increased postdelivery EPDS scores.

CONCLUSION

No significant association was found between high pain catastrophizing and probable PND; however, high predelivery pain catastrophizing, presence of breakthrough pain during epidural analgesia, and lower BMI at term were associated with increased postdelivery EPDS scores. Further research will be needed to validate this association in the context of the risk of PND development.

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.

The impact of analgesic intervention during the second stage of labour: a retrospective cohort study

PURPOSE

The incidence of epidural top-ups received in the second stage of labour in nulliparous women and the obstetrical and neonatal implications associated with these boluses are explored in this retrospective observational study. We hypothesized that an epidural top-up in the second stage of labour reduces operative deliveries by resolving inadequate analgesia.

METHODS

A population-based cohort analysis was performed using perinatal data from 1 January 2013 through 31 December 2014. An anesthesia database provided information to determine the top-up incidence. Women with or without a top-up for second-stage duration were compared for method of delivery and neonatal characteristics using descriptive statistics. Logistic regression identified predictive factors for method of delivery.

RESULTS

Of the 1,462 women with a second stage of labour > one hour who received epidural analgesia, 105 (7%) required a top-up during the second stage of labour. Women who received a top-up were more likely to have had induction of labour and/or augmentation (89% vs 76%; odds ratio [OR], 2.43; 95% confidence interval [CI], 1.32 to 4.49; P = 0.003), a longer second stage (303 min vs 171 min; mean difference, 132 min; 95% CI, 113 to 151; P < 0.001), and more assisted vaginal (41% vs 17%; OR, 3.35; 95% CI, 2.21 to 5.1; P < 0.001) or Cesarean deliveries (26% vs 11%; OR, 3.04; 95% CI, 1.91 to 4.8; P < 0.001) than women without a top-up.

CONCLUSION

Most women who received a top-up had a vaginal (spontaneous or assisted) delivery. Compared with women without a top-up, women requiring a top-up had more predictors of difficult labour and higher rates of assisted vaginal delivery and Cesarean delivery.

Epidural Analgesia During the Second Stage of Labor: A Randomized Controlled Trial

OBJECTIVE

To evaluate whether maintaining a motor-sparing epidural analgesia infusion affects the duration of the second stage of labor in nulliparous parturients compared with a placebo control.

METHODS

We conducted a double-blind, randomized, placebo-controlled trial involving nulliparous women with term cephalic singleton pregnancies who requested epidural analgesia. All women received epidural analgesia for the first stage of labor using 0.08% ropivacaine with 0.4 micrograms/mL sufentanil with patient-controlled epidural analgesia. At the onset of the second stage of labor, women were randomized to receive a blinded infusion of the same solution or placebo saline infusion. The primary outcome was the duration of the second stage of labor. A sample size of 200 per group (400 total) was planned to identify at least a 15% difference in duration.

RESULTS

Between March 2015 and September 2015, 560 patients were screened and 400 patients (200 in each group) completed the study. Using an intention-to-treat analysis, the duration of the second stage was similar between groups (epidural 52±27 minutes compared with saline 51±25 minutes, P=.52). The spontaneous vaginal delivery rate was also similar (epidural 193 [96.5%] compared with saline 198 [99%], P=.17). Pain scores were similar between groups at each measurement during the second stage. More women who received placebo reported satisfaction scores of 8 or less (epidural 32 [16%] compared with saline 61 [30.5%], P=.001).

CONCLUSION

Maintaining the infusion of epidural medication had no effect on the duration of the second stage of labor compared with a placebo infusion. Maternal and neonatal outcomes were similar. A low concentration of epidural local anesthetic does not affect the duration of the second stage of labor.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Register, http://www.chictr.org.cn/enindex.aspx, ChiCTR-IOR-15005875.

Analysis and evaluation of the effectiveness of epidural analgesia and its relationship with eutocic or dystocic delivery

OBJECTIVE

Numerous studies have demonstrated the difference in the verbal rating scale with regard to obstructed labour and induced labour, so that obstructed labour and foetal macrosomia have been related to a greater sensation of pain during labour, particularly in the first stage. Even the epidural analgesia is linked to the need for instrumented or caesarean section due to foetal obstruction. The goal of the study is to analyze and evaluate the effectiveness of epidural analgesia in normal versus obstructed labour.

PATIENTS AND METHODS

One hundred and eighty pregnant women were included in an observational, analytical, longitudinal and prospective study, that was performed in the Obstetrics Department of the Hospital Universitario Dexeus. All the nulliparous or multiparous over 36 weeks of pregnancy, after 3cm of cervical dilatation in spontaneous or induced labor were included. All the patients were given epidural analgesia according to protocol.

RESULTS

The basic descriptive methods were used for the univariate statistical analysis of the sample and the Mann-Whitney U test was used for the comparison of means between both groups. The correlations between variables were studied by means of the Spearman coefficient of correlation. The differences regarded as statistically significant are those whose P<.05.

CONCLUSION

In our population there were no statistically significant differences in the effectiveness of epidural analgesia in normal versus obstructed labour. Patients who got epidural analgesia and had obstructed labors have the same degree of verbal rating scale as patients that do not had obstructed labors (P>.05).

Should Nitrous Oxide Be Used for Laboring Patients?

Nitrous oxide, long used during labor in Europe, is gaining popularity in the United States. It offers many beneficial attributes, with few drawbacks. Cost, safety, and side effect profiles are favorable. Analgesic effectiveness is highly variable, yet maternal satisfaction is often high among the women who choose to use it. Despite being less effective in treating labor pain than neuraxial analgesic modalities, nitrous oxide serves the needs and preferences of a subset of laboring parturients. Nitrous oxide should, therefore, be considered for inclusion in the repertoire of modalities used to alleviate pain and facilitate effective coping during labor.

The degree of labor pain at the time of epidural analgesia in nulliparous women influences the obstetric outcome

Background

The increased pain at the latent phase can be associated with dysfunctional labor as well as increases in cesarean delivery frequency. We aimed to research the effect of the degree of pain at the time of epidural analgesia on the entire labor process including the mode of delivery.

Methods

We performed epidural analgesia to 102 nulliparous women on patients' request. We divided the group into three based on NRS (numeric rating scale) at the moment of epidural analgesia; mild pain, NRS 1-4; moderate pain, NRS 5-7; severe pain, NRS 8-10. The primary outcome was the mode of delivery (normal labor or cesarean delivery).

Results

There were significant differences in the mode of delivery among groups. Patients with severe labor pain had a significantly higher cesarean delivery compared to patients with moderate labor pain (P = 0.006). The duration of the first and second stage of labor, fetal heart rate, use of oxytocin and premature rupture of membranes had no differences in the three groups.

Conclusions

Our research showed that the degree of pain at the time of epidural analgesia request might influence the rate of cesarean delivery. Further research would be necessary for clarifying the mechanism that the augmentation of pain affects the mode of 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.

Epidural analgesia in labour and risk of caesarean delivery

BACKGROUND

A Cochrane Systematic Review of randomised controlled trials of epidural analgesia compared with other or no analgesia in labour reported no overall increased risk of caesarean delivery. However, many trials were affected by substantial non-compliance, and there are concerns about the external validity of some trials for contemporary maternity populations. We aimed to explore the association between epidural analgesia in labour and caesarean delivery in clinical practice and compare with findings from randomised controlled trials.

METHODS

Population-based cohort of pregnant women (n = 210 708) without major obstetrical complications who delivered a singleton live infant in hospitals in New South Wales, Australia, 2007-10. Data were obtained from linked, validated population-based data collections. Propensity score matching was used to examine the association between epidural analgesia in labour and caesarean delivery.

RESULTS

Epidural analgesia in labour was used by a third (31.5%, n = 66 317) of the women, and 9.8% (n = 20 531) had a caesarean delivery. Epidural analgesia in labour was associated with increased risk of caesarean delivery {risk ratio [RR] 2.5, [95% confidence interval (CI) 2.5, 2.6]}. The association with epidural analgesia in labour was higher for caesarean delivery for failure to progress {RR 3.0, [95% CI 2.9, 3.0]} than for caesarean delivery for fetal distress {RR 1.9, [95% CI 1.8, 2.0]}.

CONCLUSIONS

Epidural analgesia in labour is associated with caesarean delivery in a large maternity population. Population-based studies contribute important data about obstetrical care, when research settings and participants may not represent the clinical settings or broader population in which obstetrical interventions in labour are applied.

Neuraxial analgesia: a review of its effects on the outcome and duration of labor

Labor pain is one of the most challenging experiences encountered by females during their lives. Neuraxial analgesia is the mainstay analgesic for intrapartum pain relief. However, despite the increasing use and undeniable advantages of neuraxial analgesia for labor, there have been concerns regarding undesirable effects on the progression of labor and outcomes. Recent evidence indicates that neuraxial analgesia does not increase the rate of Cesarean sections, although it may be associated with a prolonged second stage of labor and an increased rate of instrumental vaginal delivery. Even when neuraxial analgesia is administered early in the course of labor, it is not associated with an increased rate of Cesarean section or instrumental vaginal delivery, nor does it prolong the labor duration. These data may help physicians correct misconceptions regarding the adverse effects of neuraxial analgesia on labor outcome, as well as encourage the administration of neuraxial analgesia in response to requests for pain relief.

The influence of analgesia on labor--is it related to primary cesarean rates?

Multiple observational studies have reported an association between neuraxial (epidural, spinal, or combined spinal-epidural) labor analgesia and cesarean delivery. The purpose of this review is to summarize data from controlled trials addressing the question of whether neuraxial labor analgesia causes an increased risk of cesarean delivery. Additionally, the review will discuss whether the timing of initiation of analgesia or the specific type of neuraxial analgesia influences mode of delivery. Finally, the issue of external validity of published trials will be discussed.

The effects of hydrotherapy on anxiety, pain, neuroendocrine responses, and contraction dynamics during labor

BACKGROUND

Hydrotherapy (immersion or bathing) is used worldwide to promote relaxation and decrease parturient anxiety and pain in labor, but the psychophysiological effects of this intervention remain obscure.

DESIGN

A pretest-posttest design with repeated measures was used to examine the effects of hydrotherapy on maternal anxiety and pain, neuroendocrine responses, plasma volume shift (PVS), and uterine contractions (CXs) during labor. Correlations among variables were examined at three time points (preimmersion and twice during hydrotherapy).

METHODS

Eleven term women (mean age 24.5 years) in spontaneous labor were immersed to the xiphoid in 37 degrees C water for 1 hr. Blood samples and measures of anxiety and pain were obtained under dry baseline conditions and repeated at 15 and 45 min of hydrotherapy. Uterine contractions were monitored telemetrically.

RESULTS

Hydrotherapy was associated with decreases in anxiety, vasopressin (V), and oxytocin (O) levels at 15 and 45 min (all ps < .05). There were no significant differences between preimmersion and immersion pain or cortisol (C) levels. Pain decreased more for women with high baseline pain than for women with low baseline levels at 15 and 45 min. Cortisol levels decreased twice as much at 15 min of hydrotherapy for women with high baseline pain as for those with low baseline pain. beta-endorphin (betaE) levels increased at 15 min but did not differ between baseline and 45 min. During immersion, CX frequency decreased. A positive PVS at 15 min was correlated with contraction duration.

CONCLUSIONS

Hydrotherapy during labor affects neuroendocrine responses that modify psychophysiological processes.

Labor pain at the time of epidural analgesia and mode of delivery in nulliparous women presenting for an induction of labor

OBJECTIVE

To assess whether the degree of labor pain at the initiation of neuraxial analgesia is associated with mode of delivery.

METHODS

Nulliparous women who presented to the labor department for an induction of labor, who were between 37 and 41 weeks of gestation, and who requested labor epidural analgesia with a pain score of 0-3 (low pain) and a cervical dilatation less than 4 cm were assessed retrospectively. Maternal and neonatal outcome including mode of delivery and duration of labor were compared with a similar group of women with pain scores of 4-6 (moderate pain), and 7-10 (severe pain). Assessing whether there was an association between pain level at the time of epidural and operative delivery rates was analyzed using a chi test for trend and by logistic regression to include potentially relevant covariates.

RESULTS

We found 185 nulliparous women with low pain and compared them with a randomly selected equal number of women in each of the other pain groups. There was no significant association between pain groups in terms of duration of the first or second stage of labor or mode of delivery. Women with low pain had an operative delivery rate (instrumental assisted vaginal delivery plus cesarean delivery) of 49%, compared with 45% and 45% in those with moderate and severe pain, respectively (P=.40).

CONCLUSION

We did not find an association between the degree of labor pain at initiation of epidural analgesia and mode of delivery or duration of labor.

LEVEL OF EVIDENCE

II.

[Obstetric anaesthesia for instrumental vaginal delivery]

The aim of the anaesthesia for instrumental delivery is to provide optimal operation conditions for the obstetrician, appropriate maternal comfort, altogether with safety for the mother and her foetus. The type and location for this intervention are chosen individually for each case according to the indication, the risk of caesarean section and the local specificities. The general safety recommendations for obstetric anaesthesia apply in every case. Since an epidural analgesia is often already working, this type of anaesthesia is the most frequently used for the extractions. A spinal anaesthesia is a logical choice where an epidural in sot yet working. The pudendal block is a second line choice and the general anaesthesia remains as the last alternative in acute emergencies, in cases of failed regional anaesthesia or when the mother refuses any other anaesthesia despite proper information or proves unable to cooperate.

Impact of pain level on second-stage delivery outcomes among women with epidural analgesia: results from the PEOPLE study

OBJECTIVE

The objective of the study was to assess the effect of suboptimal second-stage pain control on the risk of difficult delivery.

STUDY DESIGN

We conducted a secondary analysis of the Pushing Early Or Pushing Late with Epidural (PEOPLE) randomized, controlled trial cohort on second-stage nulliparous women. We defined suboptimal pain control as a visual analog pain scale score of 30 or greater on a scale of 100 and evaluated initial postrandomization and subsequent pain control on obstetrical interventions and outcomes. We estimated adjusted relative risk for caesarean delivery using logistic regression models to control for confounding variables and to evaluate the role of effect measure modifiers.

RESULTS

One thousand seven hundred fifty-six women were included in the cohort, of which 1565 (89.1%) had optimal analgesia and 191 (10.9%) had suboptimal analgesia. Women with suboptimal analgesia had an increased risk of cesarean delivery of 2.97 (1.52-5.80), midpelvic procedures of 1.83 (1.10-3.05), and third- and fourth-degree perineal tears of 1.82 (1.03-3.21). As compared with women with sustained optimal analgesia, increasing levels of pain were associated with an increase in difficult deliveries, 2.19 (1.50-3.21). The improvement of relief among women with initial suboptimal initial analgesia did not alter the risk of difficult deliveries.

CONCLUSION

Although most women achieve optimal epidural analgesia, the inability to sustain optimal epidural analgesia is associated with an increased risk of adverse second-stage obstetrical outcomes.

Effects of epidural lidocaine analgesia on labor and delivery: a randomized, prospective, controlled trial

Background

Whether epidural analgesia for labor prolongs the active-first and second labor stages and increases the risk of vacuum-assisted delivery is a controversial topic. Our study was conducted to answer the question: does lumbar epidural analgesia with lidocaine affect the progress of labor in our obstetric population?

Method

395 healthy, nulliparous women, at term, presented in spontaneous labor with a singleton vertex presentation. These patients were randomized to receive analgesia either, epidural with bolus doses of 1% lidocaine or intravenous, with meperidine 25 to 50 mg when their cervix was dilated to 4 centimeters. The duration of the active-first and second stages of labor and the neonatal apgar scores were recorded, in each patient. The total number of vacuum-assisted and cesarean deliveries were also measured.

Results

197 women were randomized to the epidural group. 198 women were randomized to the single-dose intravenous meperidine group. There was no statistical difference in rates of vacuum-assisted delivery rate. Cesarean deliveries, as a consequence of fetal bradycardia or dystocia, did not differ significantly between the groups. Differences in the duration of the active-first and the second stages of labor were not statistically significant. The number of newborns with 1-min and 5-min Apgar scores less than 7, did not differ significantly between both analgesia groups.

Conclusion

Epidural analgesia with 1% lidocaine does not prolong the active-first and second stages of labor and does not increase vacuum-assisted or cesarean delivery rate.

A Randomized Comparison of Programmed Intermittent Epidural Bolus with Continuous Epidural Infusion for Labor Analgesia

Bolus injection through an epidural catheter may result in better distribution of anesthetic solution in the epidural space compared with continuous infusion of the same anesthetic solution. In this randomized, double-blind study we compared total bupivacaine consumption, need for supplemental epidural analgesia, quality of analgesia, and patient satisfaction in women who received programmed intermittent epidural boluses (PIEB) compared with continuous epidural infusion (CEI) for maintenance of labor analgesia. The primary outcome variable was bupivacaine consumption per hour of analgesia. Combined spinal epidural analgesia was initiated in multiparas scheduled for induction of labor with cervical dilation between 2 and 5 cm. Subjects were randomized to PIEB (6-mL bolus every 30 min beginning 45 min after the intrathecal injection) or CEI (12-mL/h infusion beginning 15 min the after the intrathecal injection). The epidural analgesia solution was bupivacaine 0.625 mg/mL and fentanyl 2 microg/mL. Breakthrough pain in both groups was treated initially with patient-controlled epidural analgesia (PCEA) followed by manual bolus rescue analgesia using bupivacaine 0.125%. The median total bupivacaine dose per hour of analgesia was less in the PIEB (n = 63) (10.5 mg/h; 95% confidence interval, 9.5-11.8 mg/h) compared with the CEI group (n = 63) (12.3 mg/h; 95% confidence interval, 10.5-14.0 mg/h) (P < 0.01), fewer manual rescue boluses were required (rate difference 22%, 95% confidence interval of difference 5% to 38%), and satisfaction scores were higher. Labor pain, PCEA requests, and delivered PCEA doses did not differ. PIEB combined with PCEA provided similar analgesia, but with a smaller bupivacaine dose and better patient satisfaction compared with CEI with PCEA for maintenance of epidural labor analgesia.

Epidural catheter function during labor predicts anesthetic efficacy for subsequent cesarean delivery

One of the benefits of labor epidural analgesia is that the catheter can be used to initiate a surgical block should the need for cesarean delivery arise. However, sometimes it is not possible to obtain adequate surgical anesthesia via a previously placed labor epidural catheter and it is unknown what factors are associated with this failure. We retrospectively investigated the incidence of failure to convert a labor epidural to a successful surgical block in our institution over a period of one year and determined the factors associated with this failure. There were 246 cases in which a patient had an epidural catheter placed for labor and then had a cesarean delivery. Of these 246 cases, 220 developed surgical anesthesia using the catheter. In six cases the anesthesiologist did not attempt to use the epidural catheter for the cesarean delivery. In 20 cases (classified as failed blocks), the catheter was injected, but another method of anesthesia was then used. Factors associated with failure of the epidural block were an increased requirement for supplemental local anesthetic boluses during labor in order to provide adequate analgesia and that the attending anesthesiologist for the cesarean delivery was not a specialist in obstetric anesthesia. Most epidural catheters placed for labor can be used to induce a surgical block. When significantly more local anesthetic than usual is required to maintain analgesia during labor, however, the epidural catheter may not be functioning properly and consideration should be given to replacing it.

The effect of family physician timing of maternal admission on procedures in labour and maternal and infant morbidity

OBJECTIVE

To determine if a family physician practice pattern of early admission is associated with increased rates of intervention in labour and delivery, and/or adverse maternal and newborn outcomes.

METHOD

A retrospective cohort study compared women under the care of family physicians having 50% or more of their patients admitted to the labour and delivery unit "early" (defined as a cervical dilatation of < or =3 cm) to women under the care of family physicians having less than 50% of their patients admitted "early." Outcome measures included labour intervention rates and maternal and neonatal morbidity.

RESULTS

After adjusting for maternal characteristics, care by family physicians with a practice of early admission was associated with increased rates of electronic fetal monitoring (odds ratio [OR], 1.55; 95% confidence interval [CI], 1.27-1.89), epidural analgesia (OR, 1.34; 95% CI, 1.15-1.55), and Caesarean section (OR, 1.33; 95% CI, 1.00-1.65) compared to family physicians with a practice pattern of late admission. Malposition in labour was associated with more interventions in labour than was family physician practice pattern.

CONCLUSION

Women under the care of family physicians with a practice pattern of early admission were more likely to receive electronic fetal monitoring, epidural analgesia, and Caesarean section than women under the care of family physicians with a practice pattern of late admission. Malposition in labour had a greater effect on procedure use than any other variable in our model.

Douleur et analgésie obstétricales

GOAL AND METHODS

Labor pain is of major concern since most parturients experience significant pain of extremely severe intensity for many. The purpose of this review was to provide an overview of the mechanisms and pathways of labor pain (including new insights on integration of the nociceptive signal) and to emphasize the need of effective labor pain relief.

RESULTS

Labor pain can have deleterious effects on the mother, on the fetus and on labor outcome itself. Among the current methods of obstetric analgesia, regional analgesia (the most widespread technique being epidural analgesia) offers the best effectiveness/safety ratio thanks to pharmacological innovations. Systemic analgesia (parenteral opioids, nonopioid painkillers and inhaled anesthetic agents) provides an alternative to regional analgesia but remains less effective and more hazardous. Non-drug approaches (namely psychoprophylaxis and physical methods) may be effective when used with epidural analgesia but are often not potent enough when used alone.

CONCLUSION

Despite its complex pathophysiology, labor pain can be efficiently managed. Thanks to multidisciplinary care, obstetric analgesia (mainly epidural analgesia) prevents deleterious effects of labor pain on the mother and fetus.

Use of odds ratios on anaesthesia related studies

In line with other medical journals, odds ratios are increasingly being reported in anaesthesia literature. The frequency of the use of odds ratio and how well it relates to the relative risk when it is interpreted as relative risk remains unknown. We investigated the use of odds ratio, and its relationship to relative risk and the incidence of outcome in this study. We identified 60 meta-analyses and 87 original articles that reported odds ratios. While relative risk could have been reported in 79% of the studies, only a small proportion (3%) of these studies have estimated and reported the relative risk in addition to the odds ratio. There is a significant bias if odds ratio is interpreted as relative risk, especially so when the incidence of outcome is high. While odds ratio is a valid measure of treatment effect in its own right, anaesthetists and investigators should be careful not to interpret odds ratio as equivalent to relative risk.

Pushing in labor: performance and not endurance

OBJECTIVE

It is believed that delivery is faster if women are instructed to voluntarily bear down in synchrony with their uterine contractions. Confronted by the large variance in the duration of the second stage of labor, many clinicians attribute a "fast" or a "short" expulsion time solely to the patient's willingness to cooperate or to the strength of epidural anesthesia if it is a factor. Yet, knowledge of pushing performance and the factors affecting it remain limited. We investigated the maternal, fetal, and labor characteristics that influence the maternal "pushing performance" and sought to design a predictive index that prospectively identified "high" versus "low" pushing performers.

STUDY DESIGN

Intrauterine pressure (IP) was prospectively measured during the second stage of labor in 52 women recruited at one North American hospital. Recordings were begun after documentation of full cervical dilatation and descent of the fetal head to +2 station (on a -3/+3 scale). Each woman acted as her own control, received epidural anesthesia, and was alert and responsive throughout the study. Pushing (closed glottis technique) was performed in a standardized fashion. Multivariate analysis with linear regression was applied to identify significant associations between maternal, fetal, or labor characteristics as the independent variables and the percent increase in IP consequent to active pushing as the dependent variable.

RESULTS

Women in labor increase their IP 62% by actively pushing with a contraction during the second stage. A scattergram of the individual percent increase above the baseline IP integral revealed that for some women, pushing more readily increased their IP than it did for others (range, 0% to 192%). The percent increase was best calculated by a linear combination of myometrial thickness, estimated fetal weight, the maternal body mass index, and the obstetric need for labor augmentation (P =.007, r = 0.52, power = 0.975). A 66% change in IP provided the best separation between high and low pushing performance. Myometrial thickness provided the single strongest contribution to the regression equation's predictive value (P =.01, r = -0.36). A myometrial thickness of 6 mm had a specificity of 88% (but only 53% sensitivity) for the identification of women able to increase their IP by 66% over baseline.

CONCLUSIONS

In women in labor who have received epidural anesthesia, the efficiency with which maternal expulsive efforts are converted into increased IP is directly related to the patient's body mass index but inversely related to myometrial thickness, the sonographic estimate of fetal weight, and the need for labor augmentation.

Predictors of breakthrough pain during labor epidural analgesia

Parturients who receive labor epidural analgesia may experience breakthrough pain that requires supplemental medications. We investigated the factors associated with breakthrough pain. This prospective observational study included 1963 parturients who received epidural analgesia. Subjects were categorized into two groups on the basis of the number of episodes of breakthrough pain: the Recurrent Breakthrough Pain (RBP) group experienced three or more episodes. Univariate and multivariate regression analyses were used to evaluate factors associated with the RBP group. By multivariate analysis, nulliparity, heavier fetal weight, and epidural catheter placement at an earlier cervical dilation were found to be independently associated with the RBP group. These factors may predict which parturients' analgesia may be complicated by breakthrough pain. Parturients who received a combined spinal/epidural technique were less likely to be associated with the RBP group. The combined spinal/epidural technique may be superior to conventional epidural anesthesia, because breakthrough pain occurred less often. It is interesting to note that the characteristics that are associated with the RBP group are similar to those that have been associated with increased severity of maternal pain.

IMPLICATIONS

Nulliparity, heavier fetal weight, and epidural catheter placement at an early cervical dilation are predictors of breakthrough pain during epidural labor analgesia. The combined spinal/epidural technique may be associated with a decreased incidence of breakthrough pain.

Intensity of Labor Pain and Cesarean Delivery

Some authors have suggested that the intensity of labor pain may be related to labor dystocia. We performed a secondary analysis of a previously published randomized investigation of the effects of epidural analgesia during labor compared with patient-controlled IV meperidine on cesarean delivery. Two-hundred-fifty-nine women who received patient-controlled IV meperidine were identified for analysis. All women were in spontaneous labor with a singleton, term gestation. Women requiring 50 mg or more of meperidine per hour during labor were compared with those who required <50 mg/h. In addition, their pain scores (visual analog scale) were compared before and after analgesia administration. Pain scores were significantly higher in women requiring 50 mg/h of meperidine (8.7 vs 8.0, P = 0.05), and their labors tended to be longer (9 vs 5 h, P = 0.09). More cesarean deliveries for obstructed labor were performed in women requiring >50 mg/h of meperidine (14% vs 1.4%, P = 0.001). Neonatal outcomes were similar in the two groups.

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.