Oxytocin augmentation of dysfunctional labor. II. Uterine activity data

Defining arrest in the first and second stages of labor

Normal labor is identified as regular uterine contractions in addition to dilation and effacement of the cervix. It is necessary to define normal labor in order to delineate when a woman's labor pattern diverges from that observed in most women. Labor irregularities are subdivided into protraction disorders and arrest disorders. Identifying abnormal labor patterns and initiating appropriate interventions is essential because prolonged labor is associated with an increase in perinatal morbidity. The aim of this review was to delineate both normal labor progress and also discuss the current evidence-based diagnosis and treatment of protraction and arrest disorders. Many subtleties go into defining the boundaries of the first and second stages of labor. Historically, the Friedman curve established normal limits; but currently Zhang has advanced these definitions by accounting for current demographical characteristics and practice environments. The most significant variables for defining normal progress of labor are parity and regional anesthesia status. The most common causes of labor abnormalities are uterine inactivity, obesity, cephalopelvic disproportion and fetal malposition. Risks of extending the first and/or second stage of labor include postpartum hemorrhage, intraamniotic infection and potentially an increase in neonatal adverse outcomes. The management of labor disorders consists of oxytocin administration, amniotomy, intrauterine pressure catheter use and shared decision-making regarding proceeding with expectant management, operative vaginal delivery or cesarean delivery after weighing the risks and benefits of each option. The decision to extend the duration of labor is personalized for each mother-baby dyad and should be agreed upon depending on individual maternal and fetal circumstances.

Stopping Oxytocin in Active Labor Rather Than Continuing it until Delivery: A Viable Option for the Induction of Labor

OBJECTIVE

Induction of labor (IOL), using intravenous oxytocin, is the artificial initiation of labor before its spontaneous onset for the purpose of delivery of the fetoplacental unit. Although there are various studies looking at dosages of oxytocin, only a few have addressed the issue of discontinuation of oxytocin in the active stage of labor. Thus, our study was conducted to evaluate the need for continuation versus discontinuation of oxytocin during active labor.

METHODS

This prospective, randomized controlled trial included 106 women who needed IOL. Oxytocin infusion was initiated at a rate of 3mIU/min and was incremental until 4-6cm cervical dilation. At this point the patients were randomly assigned into one of two groups. In group one, oxytocin was discontinued, and infusion was continued with 0.9% sodium chloride solution. In group two, oxytocin was continued at the same dose until delivery.

RESULTS

The duration of oxytocin infusion was 5.5 hours in the oxytocin discontinuation group and 11.0 hours in oxytocin continuation group (p<0.001). The total dose of oxytocin was significantly higher in group two (6.1 units vs. 16.5 units; p=<0.001). The induction-delivery interval was significantly less in group one (9.1 and 11.2 hours in group one and group two, respectively; p=0.023).

CONCLUSION

Oxytocin discontinuation in the active stage of labor did not prolong the active stage. The total duration of labor and total oxytocin dose were significantly less in the oxytocin discontinuation group. Our results suggest that oxytocin discontinuation is an alternative and viable option particularly in resource poor and economically challenged settings. It not only reduces the need for intense monitoring and prolonged oxytocin use-associated dangers but reduces the total cost of labor management.

Induction of labour

OBJECTIVE

To review the most current literature in order to provide evidence-based recommendations to obstetrical care providers on induction of labour.

OPTIONS

Intervention in a pregnancy with induction of labour.

OUTCOMES

Appropriate timing and method of induction, appropriate mode of delivery, and optimal maternal and perinatal outcomes.

EVIDENCE

Published literature was retrieved through searches of PubMed, CINAHL, and The Cochrane Library in 2010 using appropriate controlled vocabulary (e.g., labour, induced, labour induction, cervical ripening) and key words (e.g., induce, induction, augmentation). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to the end of 2010. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The evidence in this document was rated using criteria described in the Report of the Canadian Task Force on Preventative Health Care (Table 1). SUMMARY STATEMENTS: 1. Prostaglandins E(2) (cervical and vaginal) are effective agents of cervical ripening and induction of labour for an unfavourable cervix. (I) 2. Intravaginal prostaglandins E(2) are preferred to intracervical prostaglandins E(2) because they results in more timely vaginal deliveries. (I).

Provider attitudes toward clinical protocols in obstetrics

The Johns Hopkins Oxytocin Protocol (JHOP) Survey was distributed to clinical labor and delivery staff to compare obstetrical providers' attitudes toward clinical protocols and the JHOP. Agreement by registered nurses (RNs), physicians in training (PIT), and attending physicians (APs) and certified nurse midwives (CNMs) was assessed with each of 4 attitudinal statements regarding whether clinical protocol and JHOP use result in better practice and are important to ensure patient safety. Odds of agreement with positive statements regarding clinical protocols did not differ significantly among groups. Odds of agreement with JHOP use resulting in better practice also did not differ significantly among provider groups. Odds of agreement with the JHOP being important to ensure patient safety were lower for the AP/CNM group compared with the RN group. Clinical protocol use is generally well received by obstetrical providers; however, differences exist in provider attitudes toward the use of an institutional oxytocin protocol.

A randomized clinical trial comparing misoprostol with prostaglandin E2 gel for preinduction cervical ripening

OBJECTIVE

Our purpose was to perform a randomized trial comparing intravaginal misoprostol to intravaginal prostaglandin E2 gel for preinduction cervical ripening evaluating efficacy and side effects.

STUDY DESIGN

Seventy-five women seen for induction of labor were randomized to receive 100 micrograms of intravaginal misoprostol or 5 mg of pharmacy-prepared intravaginal prostaglandin E2 gel for cervical ripening before oxytocin induction. Six hours after placement of the study agent, patients were given oxytocin if they were not in labor. The primary outcome measure was induction-to-delivery time; secondary measures were change in Bishop score, delivery mode, and side effects. Results were analyzed by the Student t test and Fisher's exact test, with p < 0.05 considered significant.

RESULTS

There was no difference in the incidence of primiparity or the median initial Bishop score between the two study groups. The mean time to delivery and the need for oxytocin was significantly less for subjects receiving misoprostol. There was no difference in the incidence of uterine hyperstimulation syndrome or cesarean delivery between the groups.

CONCLUSIONS

This randomized clinical trial indicates that misoprostol is efficacious for preinduction cervical ripening. Misoprostol use resulted in a significantly shorter induction-to-delivery time compared with prostaglandin E2 gel use. The side effects associated with misoprostol may be dose related, and further studies to identify the optimum dosage and interval are needed.

Randomized trial of two doses of the prostaglandin E1 analog misoprostol for labor induction

OBJECTIVE

Our purpose was to compare the safety and effectiveness of intravaginally administered misoprostol at doses of 25 micrograms and 50 micrograms for indicated labor induction in patients with an unfavorable cervix.

STUDY DESIGN

Three hundred ninety-nine patients received either 25 micrograms or 50 micrograms of misoprostol, placed intravaginally in the posterior fornix, in this randomized double-blind trial. The dose was repeated every 3 hours until adequate labor was achieved (at least three contractions in 10 minutes).

RESULTS

Among 399 patients evaluated, 192 patients were allocated to the 25 micrograms group and 207 patients to the 50 micrograms group. The start-to-delivery interval was shorter in the 50 micrograms group (826 minutes vs 970 minutes, p = 0.02). The incidence of vaginal delivery after one dose was higher in the 50 micrograms group (38.2% vs 25.0%, p = 0.007). Patients receiving 25 micrograms required oxytocin augmentation more frequently than did those receiving 50 micrograms (27.1% vs 16.9%, p = 0.02). No differences were noted in the cesarean or other operative delivery rates among patients in the two treatment groups. The incidence of newborns with a cord pH < 7.16 was greater in the 50 micrograms group (13.0% vs 6.8%, p = 0.04). Although the incidence of hyperstimulation was similar between the groups, the incidence of tachysystole was higher in the 50 micrograms group (32.8% vs 15.6%, p = 0.0001).

CONCLUSIONS

Although a dose of 50 micrograms is associated with a shorter start-to-delivery interval and a higher incidence of vaginal delivery after one dose, 25 micrograms of intravaginal misoprostol is effective and associated with a lower incidence of tachysystole and cord pH values < 7.16.

Early versus late amniotomy for labor induction: a randomized trial

OBJECTIVE

Our purpose was to determine the impact of early and late amniotomy on labor induction with continuous oxytocin infusion at term.

STUDY DESIGN

A total of 209 women admitted for labor induction were randomized to early or late amniotomy. The early amniotomy group (n = 106) had membranes ruptured as soon as it was deemed safe and feasible. The late amniotomy group (n = 103) had membrane rupture performed at > or = 5 cm dilatation. The first 103 women received a continuous oxytocin infusion with incremental adjustments at 60-minute intervals as required. The next 106 women had adjustments every 30 minutes as required. Statistical analysis was confined to concurrent groups.

RESULTS

Early amniotomy was associated with shorter labor (13.3 vs 17.8 hours, p = 0.001), chorioamnionitis (22.6% vs 6.8%, p = 0.002), and significant fetal umbilical cord compression (12.3% vs 2.9%, p = 0.017). The benefit regarding shortening of labor was limited to women having oxytocin increments every 30 minutes as required (13.3 vs 17.8 hours, p = 0.001). Alternatively, the increase in chorioamnionitis was confined to the 60-minute group (39% vs 11%, p < 0.001), which also demonstrated a trend toward increased moderate and severe variable decelerations (19.6% vs 6.4%, p = 0.08).

CONCLUSIONS

When a protocol of 60-minute increments in oxytocin infusion rate is desired, amniotomy should be performed late in labor to reduce chorioamnionitis and significant umbilical cord compression. Alternatively, if early amniotomy is necessary, oxytocin should be adjusted every 30 minutes as tolerated.

Perinatal observations in forty-eight neurologically impaired term infants

OBJECTIVE

Our goal was to review the perinatal characteristics of 48 singleton term infants with central nervous system neurologic impairment.

STUDY DESIGN

Medical records were retrospectively reviewed for maternal characteristics, prenatal and intrapartum care patterns, neonatal course, and long-term outcome. Those patients without evidence of an obvious acute asphyxial event, traumatic delivery, or preterm birth were excluded. The study population was then subclassified according to the admission fetal heart rate pattern.

RESULTS

Of these 48 term infants the admission fetal heart rate pattern was nonreactive in 33 (69%) and reactive in 15 (31%). Maternal characteristics, prenatal care, and long-term outcome were statistically similar between the two groups. However, the nonreactive group exhibited significantly more characteristics consistent with a prior asphyxial event: thick "old" meconium, "fixed" nonreactive baseline fetal heart rate, meconium-stained skin, and meconium aspiration syndrome. In contrast, in the reactive group a fetal heart rate pattern developed that was consistent with Hon's theory for intrapartum asphyxia and manifested by a prolonged tachycardia in association with persistent nonreactivity, diminished fetal heart rate variability, and fetal heart rate decelerations.

CONCLUSIONS

Among fetuses later found to be neurologically impaired, a persistent nonreactive fetal heart rate tracing obtained from admission to delivery appears to be evidence of prior neurologic injury.

Pharmacological Management of Labor

Normal spontaneous labor at term without maternal or fetal complications does not always occur. In these situations, pharmacological intervention is often the safest and most suitable method of delivery. The pharmacological management of labor includes the use of multiple agents that alter cervical dilatation and uterine contractions, resulting in delivery of the fetus and treatment of postpartum emergencies. This article provides a description of normal and abnormal labor patterns and possible peripartum complications. The use of oxytocin, ergot derivatives, and prostaglandins for augmentation of dysfunctional labor, induction of labor, and management of peripartum emergencies is discussed to provide information on availability of product, indications for use, clinical efficacy, potential adverse effects, and contraindications to use.

The Green Bay cesarean section study. II. The physician factor as a determinant of cesarean birth rates for failed labor

OBJECTIVE

Our study was designed to develop a profile of specific labor management characteristics generally used by physicians with low versus those with high rates of cesarean sections in the care of nonprogressive labor in nulliparous patients.

STUDY DESIGN

A 4-year retrospective data set was used to analyze all patients with nonprogressive labor cared for by 11 board-certified obstetricians and gynecologists practicing full-time at two Green Bay hospitals. Variations in labor management are analyzed and tested for their effect on the rate of cesarean section for failure of labor to progress.

RESULTS

Cesarean section in nulliparous women for nonprogressive labor varied from 4.3% of all deliveries in the low group to 12.3% in the high group. Through multivariate analysis we developed a profile of specific labor management characteristics used by physicians with low versus those with high rates of cesarean section.

CONCLUSION

These techniques can be used to definitively identify management strategies that result in a decrease in cesarean rates for nonprogressive labor.

A randomized control study of oxytocin augmentation of labour. 2. Uterine activity

Uterine activity was measured in 60 women whose first labour was progressing slowly in the active phase. The mean level of active contraction area (uterine activity integral, UAI) before oxytocin augmentation was 898 (SD 458) kPas/15 min. UAI increased significantly with time, even in women not given oxytocin. UAI increased logarithmically with increasing oxytocin infusion rate. Levels of uterine activity before and after oxytocin infusion are correlated positively such that the higher the initial level of UAI the higher the UAI in response to oxytocin. However, the regression line approaches the line of identity such that even with high doses of oxytocin UAI would not be likely to exceed 2500 kPas/15 min. There is a positive correlation between uterine activity and cervical dilatation rate in unstimulated labour; however, this is less evident following oxytocin infusion. Increases in uterine activity below 1200 kPas/15 min result from both higher frequency and active pressure, whereas above 1200 kPas/15 min any increase is due mainly to a rise in frequency.

Oxytocin augmentation of dysfunctional labor. III. Multiparous patients

The effectiveness of a specific oxytocin regimen characterized by a small dose, a slow rate of oxytocin incrementation, and a specific computer-defined goal of contractile activity was evaluated. The group managed by this protocol was compared with a similar group of multiparous patients managed by the same physicians using their own choice of oxytocin therapies and electronic monitoring of intrauterine pressure. The patients managed by protocol and computer had shorter mean durations of time from onset of treatment to complete cervical dilatation and received smaller mean doses of oxytocin than the control group of patients. The most significant factor determining these results was the rate of incrementation of the oxytocin dose.