Water intoxication associated with oxytocin administration during saline-induced abortion

Oxytocin: physiology, pharmacology, and clinical application for labor management

Oxytocin is a peptide hormone that plays a key role in regulating the female reproductive system, including during labor and lactation. It is produced primarily in the hypothalamus and secreted by the posterior pituitary gland. Oxytocin can also be administered as a medication to initiate or augment uterine contractions. To study the effectiveness and safety of oxytocin, previous studies have randomized patients to low- and high-dose oxytocin infusion protocols either alone or as part of an active management of labor strategy along with other interventions. These randomized trials demonstrated that active management of labor and high-dose oxytocin regimens can shorten the length of labor and reduce the incidence of clinical chorioamnionitis. The safety of high-dose oxytocin regimens is also supported by no associated differences in fetal heart rate abnormalities, postpartum hemorrhage, low Apgar scores, neonatal intensive care unit admissions, and umbilical artery acidemia. Most studies reported no differences in the cesarean delivery rates with active management of labor or high-dose oxytocin regimens, thereby further validating its safety. Oxytocin does not have a predictable dose response, thus the pharmacologic effects and the amplitude and frequency of uterine contractions are used as physiological parameters for oxytocin infusion titration to achieve adequate contractions at appropriate intervals. Used in error, oxytocin can cause patient harm, highlighting the importance of precise administration using infusion pumps, institutional safety checklists, and trained nursing staff to closely monitor uterine activity and fetal heart rate changes. In this review, we summarize the physiology, pharmacology, infusion regimens, and associated risks of oxytocin.

Polymeric nanoparticles—Promising carriers for cancer therapy

Polymeric nanoparticles (NPs) play an important role in controlled cancer drug delivery. Anticancer drugs can be conjugated or encapsulated by polymeric nanocarriers, which are known as polymeric nanomedicine. Polymeric nanomedicine has shown its potential in providing sustained release of drugs with reduced cytotoxicity and modified tumor retention, but until now, few delivery systems loading drugs have been able to meet clinical demands, so more efforts are needed. This research reviews the current state of the cancer drug-loading system by exhibiting a series of published articles that highlight the novelty and functions from a variety of different architectures including micelles, liposomes, dendrimers, polymersomes, hydrogels, and metal–organic frameworks. These may contribute to the development of useful polymeric NPs to achieve different therapeutic purposes.

High- vs low-dose oxytocin in lean and obese women: a double-blinded randomized controlled trial

BACKGROUND

Women with obesity are likely to experience longer lengths of labor and are at an increased risk of cesarean delivery. We hypothesized that high-dose oxytocin would decrease the time to delivery in a cohort of women with obesity undergoing induction of labor.

OBJECTIVE

This study aimed to assess whether women with obesity benefited from higher doses of oxytocin for induction of labor.

STUDY DESIGN

A double-blinded randomized controlled trial was conducted to evaluate the effect of low-dose and high-dose oxytocin on length of labor. We recruited women who were undergoing induction of labor at ≥37 weeks of gestation. Patients were randomly assigned in a 1:1 ratio to receive low-dose or high-dose oxytocin stratified by obesity level (obese and lean). The primary outcome was length of time (minutes) to vaginal delivery. The secondary outcomes included overall cesarean delivery rate, cesarean delivery for labor arrest, maximum oxytocin infusion rate, oxytocin infusion discontinuation, oxytocin infusion decrease, blood loss, neonatal intensive care unit admission, and neonatal Apgar scores.

RESULTS

A total of 140 patients were randomized into receiving low-dose and high-dose oxytocin stratified into obese and lean stratum (35 for all strata). The primary outcome, time to vaginal delivery, was similar between the low-dose and high-dose oxytocin groups in the lean stratum (796 [±411] vs 694 [±466] minutes; P=.363) and the stratum with obesity (715 [±497] vs 762 [±594] minutes; P=.733). Kaplan-Meier curves between the low-dose and high-dose oxytocin groups were not significantly different in the lean stratum (P=.391) and the stratum with obesity (P=.692). There were 5 cesarean deliveries (14.29%) in the low-dose oxytocin lean stratum vs 2 cesarean deliveries (5.71%) in the high-dose oxytocin lean stratum (P=.232). There were 4 cesarean deliveries (11.43%) in the low-dose oxytocin stratum with obesity vs 1 cesarean delivery (2.86%) in the high-dose oxytocin stratum with obesity (P=.164). There was no difference in the incidence of postpartum hemorrhage between the lean stratum (P=0.526) and the stratum with obesity (P=0.212). There was no difference in mean estimated blood loss between the lean stratum (P=.472) and the stratum with obesity (P=.215).

CONCLUSION

There was no difference in time to delivery between the low-dose and high-dose oxytocin protocols in either the lean cohorts or cohorts with obesity undergoing induction of labor. We did observe a trend toward a lower rate of cesarean delivery in both lean women and women with obesity when high-dose oxytocin was used.

Methods of cervical ripening and labor induction: pharmacologic

Over the years, multiple forms and doses of pharmacologic agents have been used for cervical ripening and labor induction. This chapter will review potential criteria and article situations for choosing a particular pharmacologic agent. The discussion in this chapter will be limited to comparisons between pharmacologic agents; direct comparisons between mechanical agents and pharmacologic agents will largely be reviewed in the accompanying article: Methods of cervical ripening and labor induction: mechanical. For the purposes of this discussion, the term labor induction will be limited to patients with a "favorable cervix" by Bishop's score <6, whereas the term cervical ripening will be limited to patients with an unfavorable cervix and includes subsequent induction or augmentation of labor. Although the pharmacologic agent used for the initial cervical ripening process is the focus of this discussion, subsequent treatment with oxytocin may or may not be required for delivery.

Current pharmacotherapy options for labor induction

INTRODUCTION

Labor induction is now reported to occur in up to 30 - 40% of obstetrical patients. There are a number of pharmacological options available to facilitate labor induction, including oxytocin and analogues of prostaglandins E1 and E2, which have particular utility when labor induction necessitates cervical ripening, as when labor induction occurs in the context of an unfavorable cervix.

AREAS COVERED

This paper reviews acceptable pharmacological options for labor induction, especially when cervical ripening is required. These options include oxytocin and a number of prostaglandin formulations using dinoprostone and misoprostol. It also covers several analyses of published clinical trials (Phase-III) describing evidence of effectiveness.

EXPERT OPINION

Oxytocin is best used when labor needs to be induced in the context of a favorable cervix. When the cervix is not favorable, cervical ripening using prostaglandins should precede labor induction. Either dinoprostone or misoprostol are superior to oxytocin alone for cervical ripening. However, judicious, careful considerations need to be made at the outset of labor induction so as to balance maternal and fetal risks, and these should be guided by institutional policies that reflect the evidence-base.

Dilapan tent-gemeprost regimen vs. combinations of extra-amniotic Rivanol-Laminaria/Lamicel and oxytocin for second trimester abortion

OBJECTIVE

To compare a new regimen for second trimester abortion using Dilapan and vaginal gemeprost suppositories with extra-amniotic Rivanol instillation and oxytocin i.v. immediately or 16 h after instillation.

METHODS

A prospective study was performed in 153 women to analyze the induction-abortion interval, the use of analgesics and the complication rate. Wilcoxon's rank sum test was used for statistical evaluation.

RESULTS

The mean induction-abortion interval was significantly shorter in the Dilapan-gemeprost-treated women than in the immediate or 16-h Rivanol-oxytocin-treated women, 12.5 vs. 23.3 and 26.8 h, respectively. The 24-h cumulative abortion rate was 91% in the former group vs. 49% and 61%, respectively. The use of analgesics was less frequent among the Dilapan-gemeprost-treated women, whereas the complication rate did not differ.

CONCLUSIONS

The Dilapan-gemeprost treatment was advantageous with respect to a shorter induction-abortion interval and ease of handling. However a minority of women do not respond to this treatment and it is therefore necessary to employ alternative methods to complete the abortion in these cases.

Oxytocin induction of labour: hyponatraemia and neonatal jaundice

To determine the effects of fluid restriction in induced labour with oxytocin in 5% dextrose solution, maternal venous blood and fetal cord venous blood were examined in 164 mothers in induced labour and 29 mothers with a spontaneous onset of labour. After satisfactory uterine activity was induced either the oxytocin infusion was managed according to routine delivery unit practice (n = 36), or infusion rates were halved (n = 45), or quartered (n = 43), or discontinued (n = 40). Despite fluid restriction during labour the mean sodium concentration in maternal blood or cord blood had fallen to a similar extent in all four induced groups at delivery. Potassium, urea, creatinine, total protein, and albumin in maternal blood or cord blood were affected differently by induced labour as compared with sodium. The fall in sodium concentration in maternal blood was a more consistent reflection of the total volume of fluid received, mean infusion rates and cord blood sodium after infusion rates were quartered or discontinued. The incidence of hyponatraemia was 5% in mothers and 8% in infants. A comparison of hyponatraemic and normonatraemic cord blood showed no significant differences in serum bilirubin levels or red cell counts, but more hyponatraemic infants developed neonatal jaundice. It is suggested that in induced labour fluid restriction alone does not prevent hyponatraemia and neonatal jaundice.

Iatrogenic hyponatraemia of the newborn due to maternal fluid overload: a prospective study

Over five weeks 136 out of 246 deliveries were studied. Maternal plasma sodium concentrations were normal at admission. At delivery no significant difference was found between maternal and infant cord plasma sodium concentrations. Twenty-four of the 41 mothers who had received only oral fluids during labour had infants whose cord plasma sodium concentrations were normal. Of the 95 mothers who had been given intravenous fluids, however, only 14 infants with normal plasma sodium concentrations, 31 had a concentrations of 130 mmol (mEq)/1 or less and nine of these had a concentration of 125 mmol/1 or less. There was a highly significant inverse relation between cord plasma sodium concentration and rate of fluid administration, suggesting that hyponatraemia was due to intravenous treatment with predominantly sodium-free solutions. Endogenous antidiuretic activity probably increases during labour, and synthetic oxytocin in large doses has been shown to have an antidiuretic effect. The dose used in this study did not appear to have such an effect. Glucose solutions are often used as a vehicle for oxytocin; 83% of all fluid intake in this study was 5% or 10% glucose in water. Fluid balance in labour should be supervised closely, and oxytocin should be given in a more concentrated solution.

Oxytocin augmentation of second-trimester abortion: safe or hazardous?

The role of oxytocin in augmenting the uterine activity of second-trimester instillation abortions is controversial. To evaluate the efficacy and safety of oxytocin augmentation, we studied 10,013 women who underwent hypertonic saline instillation procedures and 1,241 women who underwent prostaglandin F2a (PGF2a) instillation procedures in the United States in the period 1971 through 1975. Data were obtained through the Joint Program for the Study of Abortion under the auspices of the Center for Disease Control, a multi-center, prospective, cohort study. We found that concurrent administration of oxytocin was associated with a significantly shorter instillation-to-abortion time for hypertonic saline, but with a significantly longer time for PGF2a. For hypertonic saline, use of concurrent oxytocin did not affect either the success rate or the major complication rate; however, it did not affect the specific type of complication that occurred. For PGF2a, use of concurrent oxytocin was associated with a lower success rate and a higher major complication rate than when PGF2a was used alone; however, the relatively small number of observations and limitations in our study design may have affected our results. When we compared the 2 main abortifacients, even when we controlled for concurrent oxytocin augmentation, unaugmented PGF2a had higher major complication rates than hypertonic saline.

Management of intrauterine fetal death with prostaglandin E2 vaginal suppositories

The recent Food and Drug Administration's approval of prostaglandin E2 (PGE2) vaginal suppositories provides the clinician with a technique for the immediate management of missed abortion and intrauterine fetal death (IUFD). During a 4-year period at our institution, 78 of 80 patients with gestations ranging from 13 to 42 weeks had pregnancy successfully terminated with PGE2 suppositories with a dose schedule of 20 mg every 2 hours. The mean interval from induction to delivery of the fetus was 8.9 hours. Fifty percent of the patients spontaneously expelled the placenta; active intervention to remove the placenta within 2 hours of delivery of the fetus is recommended to avoid excessive vaginal bleeding. The most frequently encountered side effect was a temperature elevation, which was managed by less frequent administration of the prostaglandin. Gastrointestinal side effects were minimized by premedication with antidiarrheal and antiemetic agents, which also were administered during the induction period when indicated by the patient's symptoms. A concomitant oxytocin infusion was utilized in 38 patients. In gestations of less than 24 weeks the oxytocin was administered via intravenous drip at a rate of 10 U/hour. In the case of a patient with IUFD and a gestation of 24 weeks or more, oxytocin should be administered only with a constant-rate infusion pump starting at a dose schedule of 1 mU/minute with careful titration of the dose against the monitored uterine activity. The availability of the vaginal PGE2 suppositories for missed abortion and IUFD makes it important for the clinician to fully acquaint himself with the drug, its administration, effects, and side effects.

Hyponatremic fits in oxytocin-augmented labors

Case reports of three patients who had fits as a consequence of hyponatremia are presented. Each patient was in spontaneous labor at term and received conventional doses of oxytocin for augmentation. The pathogenesis, diagnosis and treatment of this entirely iatrogenic condition are discussed. The differences between these and similar cases in the literature are stressed.

Water intoxication and Syntocinon infusion

A case of severe water intoxication with convulsion and prolonged coma, following the use of a high dose Syntocinon infusion is described. The pathogenesis and treatment of the condition are discussed.

Water intoxication and oxytocin infusion

The case reports are presented of two patients who developed water intoxication after high-dose oxytocin infusions. Plasma sodium and urine flow were studied in two further patients given high-dose oxytocin infusions. The findings are related to previously published observations.

Induction of midtrimester abortion by the combined method of continuous extravovular infusion of prostaglandin F2alpha and intracervical laminaria tents

Midtrimester abortion was successfully induced in 55 of 60 patients with continuous extraovular infusion of prostaglandin F2alpha (PGF2alpha) following the insertion of intracervical laminaria tents. Intravenous oxytocin was also used in 38 (63%) of the 60 patients. The mean induction-abortion time (IAT) was 11.72 hours +/- 1.06 SD). Abortion was completed in 40% within 8 hours, 80% within 16 hours, and 93% within 24 hours. The mean total dose of PGF2alpha was 41.9 mg. There was no significant difference in IAT between the parous patients (13.40 hours +/- 1.90 SD) and the nulliparous patients (10.41 hours +/- 1.13 SD). There was no apparent correlation between IAT and the stages of gestation (12 to 22 weeks). The five patients who failed to abort within 24 to 36 hours underwent uterine evacuation, which was easily accomplished because there was a marked degree of cervical dilatation. Side effects and complications of the technique were few. Endometritis occurred in three patients, two of whom had had intrauterine devices in situ until just prior to the procedure. It appears that this method has a high success rate, an acceptable safety factor, good patient tolerance, and relatively few side effects.

Midtrimester abortion induced by serial intravaginal administration of prostaglandin E2 suppositories in conjunction with a contraceptive diaphragm

Midtrimester abortion was successfully induced in 68 of 69 patients with serial intravaginal administration of prostaglandin E2 suppositories behind a contraceptive diaphragm. The mean abortion time for the successful inductions was 13.07 hours; multiparous patients aborted somewhat faster, mean 12.72 hours, as compared to nulliparous patients, mean 14.22 hours. In 36 patients the PGE2 suppositories were placed behind an intact diaphragm and the mean abortion time was 14.89 hours. In 33 patients the PGE2 suppositories were placed behind a diaphragm modified by having an opening incised in the center, the mean time in these patients was 11.96 hours. Of the 68 successful abortions 59% of the patients aborted in 12 hours or less and 88% aborted within 24 hours. The most frequently encountered side effect was temperature elevation of 2 degrees F or higher which occurred in 68% of the patients. Temperatures returned to normal levels within 4 to 6 hours after the last adminstration of PGE2. Gastrointestinal side effects occurred in 45% of patients, but these side effects were well tolerated and did not require termination of drug administration in any of the patients. Intravaginal administration of PGE2 suppositories is a very effective abortifacient technque during the midtrimester, however the use of PGE2 in conjunction with a diaphragm did not appreciabley improve the technique although the amount of drug administered and the incidence of side effects was somewhat lower than when the PGE2 suppositories are used alone. If a diaphragm is to be used, a modified diaphragm is indicated since it simplifies the clinical management of the abortion, eases administration of the suppositories and permits a more accurate estimation of cervical changes, vaginal bleeding and abortion.