Oxytocin administration during cesarean delivery: Randomized controlled trial to compare intravenous bolus with intravenous infusion regimen

Hypotension duration and vasopressor requirements following intrathecal oxytocin for Total hip arthroplasty: Secondary analysis of a randomized controlled trial

INTRODUCTION

A recent publication investigating intrathecal oxytocin, 100 μg, administered immediately prior to a spinal anesthetic in patients undergoing primary total hip arthroplasty surgery demonstrated a reduction in disability for 3-weeks, increased walking distance at 8-weeks, and earlier opioid cessation. This secondary analysis study was undertaken to assess the acute cardiovascular safety and analgesic efficacy of intrathecal oxytocin in this study population.

METHODS

90 patients were included in the analysis (44 randomized to spinal oxytocin and 46 to placebo [saline]). Data collected prospectively during the previously published study were supplemented with additional retrospectively collected data. The primary outcomes were comparisons of the duration of hypotension (minutes with mean arterial pressure < 65 mmHg) and cumulative vasopressor requirements during the initial 60 min following spinal placement. Secondary outcomes included hypotension durations and vasopressor requirements at later time points, perioperative fluid administration, physical therapy metrics, time to first opioid administration, cumulative opioid consumption through 24 h, and verbal pain scores through 24 h.

RESULTS

The duration of hypotension during the first 60 min following spinal placement did not differ between intrathecal oxytocin and placebo groups (12.2 ± 10.7 vs 14.0 ± 13.0 min, respectively; p = 0.476). There was also no difference in cumulative vasopressor requirements (1303 ± 883 vs 1156 ± 818 μg [phenylephrine equivalents]; p = 0.413) during that time period. No group differences were found for any of the investigated secondary outcomes.

CONCLUSION

The administration of 100 μg of intrathecal oxytocin does not significantly impact the duration of hypotension or the need for vasopressor agents when given as a component of a spinal anesthetic. The oxytocin and placebo groups also did not differ in regards to physical therapy related metrics, time to first opioid administration, cumulative opioids at 24-h, or pain scores through 24-h. What is already known on this topic: Rapid intravenous oxytocin causes hypotension after cesarean delivery, but intrathecal oxytocin does not cause hypotension in healthy volunteers.

WHAT THIS STUDY ADDS

Compared to saline control, intrathecal oxytocin, 100 μg did not increase the duration of hypotension or vasopressor requirements in patients during total hip arthroplasty. How this study might affect research, practice, or policy: Lack of hypotension from intrathecal oxytocin in this study supports future investigations to further explore its potential benefits, in terms of both analgesia and functional recovery following surgery.

Comparison of carbetocin as a bolus or an infusion with prophylactic phenylephrine on maternal heart rate during Cesarean delivery under spinal anesthesia: a double-blinded randomized controlled trial

PURPOSE

Carbetocin, an oxytocin analog, given as a postpartum hemorrhage prophylaxis in elective Cesarean deliveries, frequently causes tachycardia and hypotension. Phenylephrine infusion has been shown to prevent spinal anesthesia-induced hypotension. The goal of this study was to evaluate if a slow infusion of carbetocin would reduce maternal heart rate variation and hemodynamic disturbances compared with a rapid bolus in parturients receiving a prophylactic phenylephrine infusion during elective Cesarean delivery.

METHODS

In this double-blinded randomized controlled trial, 70 healthy parturients were allocated to either a bolus group or an infusion group. At cord clamping, participants in the bolus group received carbetocin 100 µg as a rapid intravenous bolus, while participants in the infusion group received carbetocin 100 µg over 10 min. The primary outcome was the variation in maternal heart rate from baseline during the 20 min following cord clamping. Secondary outcomes included blood pressure, cardiac output, and stroke volume variations during the study period, measured with the ClearSight™ hemodynamic monitor.

RESULTS

Maximum heart rate variation was not different between the groups: bolus group, mean (standard deviation) 29.8 (25.2)% vs infusion group, 27.2 (23.3)%; P = 0.67. The increase in heart rate occurred significantly earlier in the bolus group than in the infusion group (median [interquartile range] time, 105 [69-570] sec vs 485 [255-762] sec; P = 0.02; group × time interaction: two-way repeated measures ANOVA, P = 0.04). There was no significant difference in maximum variations for the other hemodynamic parameters between the groups.

CONCLUSION

Carbetocin infused over ten minutes did not reduce the magnitude of maternal heart rate variation but delayed its occurrence. This finding could be relevant to the anesthesiologist caring for parturients in whom a slight increase in maternal heart rate is clinically undesirable.

STUDY REGISTRATION

www.

CLINICALTRIALS

gov (NCT03404544); registered 19 January 2018.

Intravenous oxytocin dosing regimens for postpartum hemorrhage prevention following cesarean delivery: a systematic review and meta-analysis

OBJECTIVE

To compare the available evidence on intravenous oxytocin dosing regimens for the prevention of postpartum hemorrhage following cesarean delivery.

DATA SOURCES

We searched Ovid MEDLINE, Embase, Global Index Medicus, Cumulative Index of Nursing and Allied Health Literature, Cochrane Controlled Register of Trials, ClinicalTrials.gov, and the International Clinical Trials Registry Platform for eligible studies published until February 2020.

STUDY ELIGIBILITY CRITERIA

We included any randomized or nonrandomized study published in peer-reviewed journals that compared at least 2 different dosing regimens of intravenous oxytocin for postpartum hemorrhage prevention in women undergoing cesarean delivery.

METHODS

Two authors independently assessed the eligibility of studies, extracted the data, and assessed the risk of bias. The primary outcome was incidence of postpartum hemorrhage ≥1000 mL. Other review outcomes included use of additional uterotonics, blood loss, and adverse maternal events. Data were analyzed according to the type of intravenous administration (bolus only, infusion only, or bolus plus infusion) and total oxytocin dose. A meta-analysis was performed on randomized trials and the results were reported as risk ratios or mean differences with 95% confidence intervals. The Grading of Recommendations, Assessment, Development, and Evaluations scale was used to rate the certainty of evidence. Findings from dose-finding trials and nonrandomized studies were reported narratively.

RESULTS

A total of 35 studies (7333 women) met our inclusion criteria and included 30 randomized trials and 5 nonrandomized studies. There were limited data available from the trials for most outcomes, and the results were not conclusive. Compared with bolus plus infusion regimens, bolus only regimens probably result in slightly higher mean blood loss (mean difference, 52 mL; 95% confidence interval, 0.4-104 mL; moderate certainty). Among the bolus plus infusion regimens, initial bolus doses <5 IU may reduce nausea (risk ratio, 0.26; 95% confidence interval, 0.11-0.63; low certainty) when compared with doses of 5-9 IU. Total oxytocin doses of 5-9 IU vs total doses of 10-19 IU may increase the use of additional uterotonics (risk ratio, 13.00; 95% confidence interval, 1.75-96.37; low certainty). Effects on other outcomes were generally inconclusive.

CONCLUSION

There are limited data available for comparisons of IV oxytocin regimens for postpartum hemorrhage prevention following cesarean delivery. Bolus plus infusion regimens may lead to minor reductions in mean blood loss and initial bolus doses of <5 IU may minimize nausea. Bolus only regimens of 10 IU vs bolus only regimens of 5 IU may decrease the need for additional uterotonics, however, further comparative trials are required to understand the effects on other key outcomes, particularly hypotension.

Long-Acting and Selective Oxytocin Peptide Analogs Show Antidiabetic and Antiobesity Effects in Male Mice

Oxytocin (OXT) has been shown to suppress appetite, induce weight loss, and improve glycemic control and lipid metabolism in several species, including humans, monkeys, and rodents. However, OXT's short half-life in circulation and lack of receptor selectivity limit its application and efficacy. In this study, we report an OXT peptide analog (OXTGly) that is potent and selective for the OXT receptor (OXTR). OXT, but not OXTGly, activated vasopressin receptors in vitro and acutely increased blood pressure in vivo when administered IP. OXT suppressed food intake in mice, whereas OXTGly had a moderate effect on food intake when administered IP or intracerebroventricularly. Both OXT (IP) and OXTGly (IP) improved glycemic control in glucose tolerance tests. Additionally, both OXT (IP) and OXTGly (IP) stimulated insulin, glucagon-like peptide 1, and glucagon secretion in mice. We generated lipid-conjugated OXT (acylated-OXT) and OXTGly (acylated-OXTGly) and demonstrated that these molecules have significantly extended half-lives in vivo. Compared with OXT, 2-week treatment of diet-induced obese mice with acylated-OXT [subcutaneous(ly) (SC)] resulted in enhanced body weight reduction, an improved lipid profile, and gene expression changes consistent with increased lipolysis and decreased gluconeogenesis. Treatment with acylated-OXTGly (SC) also resulted in a statistically significant weight loss, albeit to a lesser degree compared with acylated-OXT treatment. In conclusion, we demonstrate that selective activation of the OXTR pathway results in both acute and chronic metabolic benefits, whereas potential activation of vasopressin receptors by nonselective OXT analogs causes physiological stress that contributes to additional weight loss.

The effect of initiating intravenous oxytocin infusion before uterine incision on the blood loss during elective cesarean section: a randomized clinical trial

Objective: This study compares the effect of starting intravenous oxytocin infusion early before uterine incision versus late after umbilical cord clamping on the blood loss during elective cesarean section (CS). Methods: A single-blinded randomized clinical trial conducted on 200 pregnant women at term (>37 weeks) gestation scheduled for elective CS were assigned to either IV infusion of 30 IU of oxytocin started before uterine incision (Group I) or started immediately after clamping the umbilical cord (Group II). The primary outcome was the mean volume of blood loss during CS. The secondary outcomes included the mean volume of postoperative blood loss, the mean reduction in the hemoglobin and hematocrit levels, the need for additional uterotonics, blood transfusion and additional surgical procedures. Results: The baseline characteristics of both groups are quiet similar. No statistical significant difference between both groups as regard to pre- and postpartum hemoglobin levels (p = .06 and 0.24 respectively) and hematocrit values (p = .12 and .51 respectively). There was a significant reduction in the intraoperative blood loss in group I compared with group II (432.7 ± 90.6 versus 588.9 ± 96.3 mL respectively, p = .001). The need for additional uterotonics was more frequent in the group II (19 women) than in group I (seven women) with statistical significance (p = .002). No differences between both groups regarding the need for blood transfusion or additional surgical procedures. Conclusions: Initiating intravenous oxytocin infusion before uterine incision during elective CS could be associated with reduction in the intraoperative blood loss and the need for additional uterotonics.

Effect of co-administration of different doses of phenylephrine with oxytocin on the prevention of oxytocin-induced hypotension in caesarean section under spinal anaesthesia: A randomised comparative study

INTRODUCTION

Co-administration of phenylephrine prevents oxytocin-induced hypotension during caesarean section under spinal anaesthesia (SA), but higher doses cause reflex bradycardia. This study compares the effects of co-administration of two different doses of phenylephrine on oxytocin-induced hypotension during caesarean section under SA.

METHODS

In this prospective, double-blind study, 90 parturients belonging to the American Society of Anesthesiologists' physical status 1 or 2, undergoing caesarean section under SA were randomised into Group A: oxytocin 3U and phenylephrine 50 μg, Group B: oxytocin 3U and phenylephrine 75 μg, Group C: oxytocin 3U and normal saline, administered intravenously over 5 min after baby extraction. The incidence of hypotension (the primary outcome), rescue vasopressor requirement and side effects were recorded. Statistical analyses were with analysis of variance, Kruskal-Wallis, chi-square and Fisher's exact tests.

RESULTS

Demographic parameters such as age, height, weight, level of sensory block at 20 min and duration of surgery were comparable in all the groups. The incidence of hypotension (Group A - 90%, Group B - 10%, Group C - 98%, P = 0.001), magnitude of fall in mean arterial pressure (Group A-15.03 ± 6.12 mm of Hg, Group B - 6.63 ± 4.49 mm of Hg and Group C-13.03 ± 3.39 mm of Hg, P < 0.001) and rescue vasopressor requirement (Group A-45 ± 15.25 mg, Group B-5 ± 15.25, Group C-91.66 ± 26.53, P < 0.001) were significantly lower in Group B compared to A and C.

CONCLUSION

Co-administration of phenylephrine 75 μg with oxytocin 3U reduces the incidence of oxytocin-induced hypotension compared to phenylephrine 50 μg with oxytocin 3U during caesarean section under spinal anaesthesia.

Oxytocin for preventing postpartum haemorrhage (PPH) in non-facility birth settings

BACKGROUND

Postpartum haemorrhage (PPH) is the single leading cause of maternal mortality worldwide. Most of the deaths associated with PPH occur in resource-poor settings where effective methods of prevention and treatment - such as oxytocin - are not accessible because many births still occur at home, or in community settings, far from a health facility. Likewise, most of the evidence supporting oxytocin effectiveness comes from hospital settings in high-income countries, mainly because of the need of well-organised care for its administration and monitoring. Easier methods for oxytocin administration have been developed for use in resource-poor settings, but as far as we know, its effectiveness has not been assessed in a systematic review.

OBJECTIVES

To assess the effectiveness and safety of oxytocin provided in non-facility birth settings by any way in the third stage of labour to prevent PPH.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register, the WHO International Clinical Trials Registry Platform (ICTRP), ClinicalTrials.gov (12 November 2015), and reference lists of retrieved reports.

SELECTION CRITERIA

All published, unpublished or ongoing randomised or quasi-randomised controlled trials comparing the administration of oxytocin with no intervention, or usual/standard care for the management of the third stage of labour in non-facility birth settings were considered for inclusion.Quasi-randomised controlled trials and randomised controlled trials published in abstract form only were eligible for inclusion but none were identified. Cross-over trials were not eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for eligibility, assessed risk of bias and extracted the data using an agreed data extraction form. Data were checked for accuracy.

MAIN RESULTS

We included one cluster-randomised trial conducted in four rural districts in Ghana that randomised 28 community health officers (CHOs) (serving 2404 potentially eligible pregnant women) to the intervention group and 26 CHOs (serving 3515 potentially eligible pregnant women) to the control group. Overall, the trial had a high risk of bias. CHOs delivered the intervention in the experimental group (injection of 10 IU (international units) of oxytocin in the thigh one minute following birth using a prefilled, auto-disposable syringe). In the control group, CHOs did not provide this prophylactic injection to the women they observed. CHOs had no midwifery skills and did not in any way manage the birth. All other CHO activities (outcome measurement, data collection, and early treatment and referral when necessary) were identical across the control and oxytocin CHOs.Although only one of the nine cases of severe PPH (blood loss greater or equal to 1000 mL) occurred in the oxytocin group, the effect estimate for this outcome was very imprecise and it is uncertain whether the intervention prevents severe PPH (risk ratio (RR) 0.16, 95% confidence interval (CI) 0.02 to 1.30; 1570 women (very low-quality evidence)). Similarly, because of the lack of cases of severe maternal morbidity (e.g. uterine rupture) and maternal deaths, it was not possible to obtain effect estimates for those outcomes (both very low-quality evidence).Oxytocin compared with the control group decreased the incidence of PPH (> 500 mL) in both our unadjusted (RR 0.48, 95% CI 0.28 to 0.81; 1569 women) and adjusted (RR 0.49, 95% CI 0.27 to 0.90; 1174 women (both low-quality evidence)) analyses. There was little or no difference between the oxytocin and control groups on the rates of transfer or referral of the mother to a healthcare facility (RR 0.72, 95% CI 0.34 to 1.56; 1586 women (low-quality evidence)), stillbirths (RR 1.27, 95% CI 0.67 to 2.40; 2006 infants (low-quality evidence)); andearly infant deaths (0 to three days) (RR 1.03, 95% CI 0.35 to 3.07; 1969 infants (low-quality evidence)). There were no cases of needle-stick injury or any other maternal major or minor adverse event or unanticipated harmful event. There were no cases of oxytocin use during labour.There were no data reported for some of this review's secondary outcomes: manual removal of placenta, maternal anaemia, neonatal death within 28 days, neonatal transfer to health facility for advanced care, breastfeeding rates. Similarly, the women's or the provider's satisfaction with the intervention was not reported.

AUTHORS' CONCLUSIONS

It is uncertain if oxytocin administered by CHO in non-facility settings compared with a control group reduces the incidence of severe PPH (>1000 mL), severe maternal morbidity or maternal deaths. However, the intervention probably decreases the incidence of PPH (> 500 mL).The quality of the one trial included in this review was limited because of the risk of attrition and recruitment biases related to limitations in the follow-up of pregnant women in both arms of the trials and some baseline imbalance on the size of babies at birth. Additionally, there was serious imprecision of the effect estimates for most of the primary outcomes mainly because of the size of the trial, very few or no events and CIs around both relative and absolute estimates of effect that include both appreciable benefit and appreciable harm.Although the trial presented data both for primary and secondary outcomes, it seemed to be underpowered to detect differences in the primary outcomes that are the ones more relevant for making judgments about the potential applicability of the intervention in other settings (especially severe PPH).Therefore, taking into account the extreme setting where the intervention was implemented, the limited role of the CHO in the trial and the lack of power for detecting effects on primary (relevant) outcomes, the applicability of the evidence found seems to be rather limited.Further well-executed and adequately-powered randomised controlled trials assessing the effects of using oxytocin in pre-filled injection devices or other new delivery systems (spray-dried ultrafine formulation of oxytocin) on severe PPH are urgently needed. Likewise, other important outcomes like possible adverse events and acceptability of the intervention by mothers and other community stakeholders should also be assessed.

A Randomized, Double-blinded Trial of a "Rule of Threes" Algorithm versus Continuous Infusion of Oxytocin during Elective Cesarean Delivery

BACKGROUND

The administration of uterotonic agents during cesarean delivery is highly variable. The authors hypothesized a "rule of threes" algorithm, featuring oxytocin 3 IU, timed uterine tone evaluations, and a systematic approach to alternative uterotonic agents, would reduce the oxytocin dose required to obtain adequate uterine tone.

METHODS

Sixty women undergoing elective cesarean delivery were randomized to receive a low-dose bolus or continuous infusion of oxytocin. To blind participants, the rule group simultaneously received intravenous oxytocin (3 IU/3 ml) and a "wide-open" infusion of 0.9% normal saline (500 ml); the standard care group received intravenous 0.9% normal saline (3 ml) and a "wide-open" infusion of oxytocin (30 IU in 0.9% normal saline/500 ml). Uterine tone was assessed at 3, 6, 9, and 12 min, and if inadequate, additional uterotonic agents were administered. Uterine tone, total dose and timing of uterotonic agent use, maternal hemodynamics, side effects, and blood loss were recorded.

RESULTS

Adequate uterine tone was achieved with lower oxytocin doses in the rule versus standard care group (mean, 4.0 vs. 8.4 IU; point estimate of the difference, 4.4 ± 1.0 IU; 95% CI, 2.60 to 6.15; P < 0.0001). No additional oxytocin or alternative uterotonic agents were needed in either group after 6 min. No differences in the uterine tone, maternal hemodynamics, side effects, or blood loss were observed.

CONCLUSION

A "rule of threes" algorithm using oxytocin 3 IU results in lower oxytocin doses when compared with continuous-infusion oxytocin in women undergoing elective cesarean delivery.

Operative care of obstetric patients

The operative care of pregnant patients, whether for delivery of the neonate or for a nonobstetric surgical procedure, must take into consideration many variables. An awareness of maternal physiologic changes, fetal requirements, effects of anesthetic agents on both the mother and the fetus, and the potential for complications is essential for obstetric anesthetists. In addition, a comprehensive evaluation of the parturient, ample preparation of drugs and equipment in the operative suite, and cooperation with the obstetrician and the surgical team are of major importance in ensuring the safe and effective anesthetic care of this special patient population.

[An update of the obstetrics hemorrhage treatment protocol]

Obstetric hemorrhage is still a major cause of maternal and fetal morbimortality in developed countries. This is an underestimated problem, which usually appears unpredictably. A high proportion of the morbidity of obstetric hemorrhage is considered to be preventable if adequately managed. The major international clinical guidelines recommend producing consensus management protocols, adapted to local characteristics and keep them updated in the light of experience and new scientific publications. We present a protocol updated, according to the latest recommendations, and our own experience, in order to be used as a basis for those anesthesiologists who wish to use and adapt it locally to their daily work. This last aspect is very important to be effective, and is a task to be performed at each center, according to the availability of resources, personnel and architectural features.