Carbetocin at elective Cesarean delivery: a sequential allocation trial to determine the minimum effective dose

A randomized controlled trial on the comparison of two doses of carbetocin with oxytocin for the prevention of postpartum hemorrhage (concert trial)

AIM

To compare the effectiveness of 50 and 100 μg of carbetocin with 10 IU of oxytocin for the prevention of postpartum hemorrhage (PPH).

METHODS

This was a triple-blind, non-inferiority trial involving pregnant women recruited at term. We compared two doses of carbetocin (50 and 100 μg) with 10 IU of oxytocin administered as uterotonic agent after vaginal or cesarean delivery. Uterine contractility was assessed at 2- and 5-min after uterotonic administration. The association between adequate uterine tone and PPH with the patients' characteristics were examined using the chi-square test. Effect of the drugs on the odds of developing PPH was examined using logistics regressions. All analyses were conducted using STATA (StataCorp L.L.C.) with a significance level set at 0.05.

RESULTS

In total, 324 women (50 μg carbetocin group-111, 100 μg carbetocin group-106, and oxytocin group-107) participated in the study. There was a significantly higher proportion of women with adequate uterine tone in those that had 100 μg carbetocin relative to 50 μg and 10 IU oxytocin at 5 min (p < 0.001). Patients who received oxytocin had a higher average blood loss than women that had either 50 or 100 μg carbetocin (p = 0.128). There was a significant difference in the need for additional uterotonic, with a higher proportion of participants among those who received 10 IU of oxytocin (p < 0.001).

CONCLUSION

Patients that had 100 μg of carbetocin had a better adequate uterine tone at the fifth minute compared to those who had 50 μg and 10 IU of oxytocin. Generally, carbetocin use was less likely associated with risk of PPH and use of additional intervention.

A Comparative Study of the Cardiovascular Effects of a Lower Dose of Heat-Stable Carbetocin Versus the Standard Dose in the Prevention of Postpartum Hemorrhage During Elective Cesarean Delivery: A Single-Blinded, Randomized, Parallel-Group Trial

INTRODUCTION

Oxytocin is a uterotonic drug that acts on receptors in the myometrium, causing uterine contractions. However, oxytocin receptors are also present in other organs, including the myocardium. Heat-stable carbetocin, a long-acting analog of oxytocin, is also known to act on these oxytocin receptors. As carbetocin has a long half-life of 40 minutes, its duration of action on the myocardium may be relatively longer than that of oxytocin. Therefore, this study aimed to study the cardiovascular effects of using a lower dose of carbetocin (50 mcg) compared to the standard dose (100 mcg) during elective cesarean delivery.

MATERIALS AND METHODS

A total of 212 full-term pregnant women were randomized into two groups: group I received 50 mcg of intravenous carbetocin, and group II received 100 mcg of intravenous carbetocin. Heart rate, blood pressure (BP), oxygen saturation, electrocardiogram changes, and pre- and postoperative (12 hours after cesarean delivery) high-sensitivity cardiac troponin I levels were compared between the groups.

RESULTS

No statistically significant differences were observed between the groups with respect to heart rate, BP, electrocardiogram changes, or difference in pre- and postoperative high-sensitivity cardiac troponin I levels (p > 0.05).

CONCLUSION

Carbetocin's cardiovascular effects were similar in both groups. None of the participants had adverse cardiovascular effects from the drug, and there were no differences in cardiovascular effects between the groups.

Uterotonics, magnesium sulphate and antibiotics during childbirth and peripartum: Important obstetric drugs for the anaesthesiologist

The main causes of maternal mortality are comorbidities, hypertensive pregnancy syndrome, obstetric haemorrhage, and maternal sepsis. For this reason, uterotonics, magnesium sulphate, and antibiotics are essential tools in the management of obstetric patients during labour and in the peripartum period. These drugs are widely used by anaesthesiologists in all departments, and play a crucial role in treatment and patient safety. For the purpose of this narrative review, we performed a detailed search of medical databases and selected studies describing the use of these drugs in patients during pregnancy, delivery and the pospartum period. Uterotonics, above all oxytocin, play an important role in the prevention and treatment of pospartum haemorrhage, and various studies have shown that in obstetric procedures, such as scheduled and emergency caesarean section, they are effective at lower doses than those hitherto accepted. We also discuss the use of carbetocin as an effective alternative that has a therapeutic advantage in certain clinical circumstances. Magnesium sulphate is the gold standard in the prevention and treatment of eclampsia, and also plays a neuroprotective role in preterm infants. We describe the precautions to be taken during magnesium administration. Finally, we discuss the importance of understanding microbiology and the pharmacology of antibiotics in the management of obstetric infection and endometritis, and draw attention to the latest trends in antibiotic regimens in labour and caesarean section.

Guideline No. 431: Postpartum Hemorrhage and Hemorrhagic Shock

OBJECTIVE

This guideline aims to provide evidence for prevention, recognition, and treatment of postpartum hemorrhage including severe hemorrhage leading to hemorrhagic shock.

TARGET POPULATION

All pregnant patients.

BENEFITS, HARMS, AND COSTS

Appropriate recognition and treatment of postpartum hemorrhage can prevent serious morbidity while reducing costs to the health care system by minimizing more costly interventions and length of hospital stays.

EVIDENCE

Medical literature, PubMed, ClinicalTrials.gov, the Cochrane Database, and grey literature were searched for articles, published between 2012 and 2021, on postpartum hemorrhage, uterotonics, obstetrical hemorrhage, and massive hemorrhage protocols.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

All members of the health care team who care for labouring or postpartum women, including, but not restricted to, nurses, midwives, family physicians, obstetricians, and anesthesiologists.

RECOMMENDATIONS

Exploring cardiac effects after oxytocin 2.5 IU or carbetocin 100 μg: A randomised controlled trial in women undergoing planned caesarean delivery

BACKGROUND

Oxytocin can stimulate release of myocardial biomarkers troponin I and T, prolong QTc and induce ST-depression.

OBJECTIVE

To explore cardiac changes after either intravenous carbetocin or oxytocin.

STUDY DESIGN

Exploratory phase 4 randomised controlled trial.

SETTING

Obstetrics units of Oslo University Hospital, Norway between September 2015 and May 2018.

PARTICIPANTS

Forty healthy, singleton pregnant women aged 18 to 50 years at gestational age at least 36 weeks with a planned caesarean delivery.

INVENTIONS

Participants were randomised to receive either oxytocin 2.5 IU or carbetocin 100 μg immediately after delivery.

MAIN OUTCOME MEASURES

The primary endpoint was the assessment of troponin I within 48 h of study drug administration. Troponin I and T, and creatine kinase myocardial band assessments were measured before spinal anaesthesia (baseline), and again at 4, 10 and 24 h after delivery. QTc, ST-depression and relative increase in heart rate were recorded from start of study drug administration to 10 min after delivery. All adverse events were monitored.

RESULTS

Compared with the carbetocin group, higher troponin I levels were observed in the oxytocin group at 4 h and 10 h after delivery. For both treatment groups, an increase from baseline in troponin I and T was most pronounced at 10 h after delivery, and it had begun to decline by 24 h. QTc increased with time after administration of both study drugs, with a mean maximum increase of 10.4 ms observed at 9 min (P  < 0.001). No statistical differences were observed in QTc (P = 0.13) or ST-depression (P = 0.11) between the treatment groups.

CONCLUSIONS

Oxytocin 2.5 IU and carbetocin 100 μg caused a similar increase in QTc. The trial was underpowered with regards to ST-depression and the release of myocardial biomarkers and these warrant further investigation. Data from this trial will inform a larger phase 4 trial to determine potential drug differences in troponin release.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02528136.

Is there a role for carbetocin in the prophylaxis of postpartum obstetric haemorrhage?

Postpartum haemorrhage is a common complication of pregnancy, most commonly due to uterine atony. Uterotonics have a vital role in preventing postpartum haemorrhage but the choice of the most effective agent with the fewest adverse effects is a subject of debate. Carbetocin, a synthetic analogue of oxytocin has been available in the UK since 2007 but is not currently widely used. It has a longer duration of action than oxytocin, which avoids the need for an infusion and as it is heat-stable it can be stored at room temperature. Current UK clinical guidelines, based on the results of older meta-analyses, do not recommend carbetocin as a first-line agent. A Cochrane review, published in 2018, ranked carbetocin in the top three drug regimens for preventing postpartum haemorrhage and an international consensus statement on uterotonic use for caesarean birth concluded that carbetocin may become the preferred drug for caesarean birth, by reducing the need for additional uterotonics. The higher cost of carbetocin when compared with oxytocin is a limiting factor, but the significant healthcare costs of a postpartum haemorrhage and the physiological impact of this event suggests it a reasonable alternative to consider, especially if ergometrine is contraindicated or in those who are undergoing a caesarean birth or are at high risk of bleeding.

Carbetocin vs. oxytocin at elective caesarean delivery: a double-blind, randomised, controlled, non-inferiority trial of low- and high-dose regimens

Carbetocin or oxytocin are given routinely as first-line uterotonic drugs following delivery of the neonate during caesarean delivery to prevent postpartum haemorrhage. Low doses may be as effective as high doses with a potential reduction in adverse effects. In this double-blind, randomised, controlled, non-inferiority trial, we assigned low-risk patients undergoing elective caesarean delivery under spinal anaesthesia to one of four groups: carbetocin 20 μg; carbetocin 100 μg; oxytocin 0.5 IU bolus + infusion; and oxytocin 5 IU bolus + infusion. The study drug was given intravenously after delivery of the neonate. Uterine tone was assessed by the obstetrician 2, 5 and 10 minutes after study drug administration according to an 11-point verbal numerical rating scale (0 = atonic, 10 = excellent tone). The primary outcome measure was uterine tone 2 min after study drug administration. The pre-specified non-inferiority margin was 1.2 points on the 11-point scale. Secondary outcomes included uterine tone after 5 and 10 minutes, use of additional uterotonics, blood loss and adverse effects. Data were available for 277 patients. Carbetocin 20 μg resulting in uterine tone of (median (IQR [range])) 8 (7-8 [1-10]) was non-inferior to carbetocin 100 μg with tone 8 (7-9 [3-10]), median (95%CI) difference 0 (-0.44-0.44). Similarly, oxytocin 0.5 IU with tone 7 (6-8 [3-10]) was non-inferior to oxytocin 5 IU with tone 8 (6-8 [2-10]), median (95%CI) difference 1 (0.11-1.89). Carbetocin 20 μg was also non-inferior to oxytocin 5 IU, and oxytocin 0.5 IU was non-inferior to carbetocin 100 μg. Uterine tone after 5 and 10 minutes, use of additional uterotonics, blood loss and adverse effects were similar in all groups.

Preventing postpartum hemorrhage after cesarean delivery: a network meta-analysis of available pharmacologic agents

BACKGROUND

Postpartum hemorrhage causes a quarter of global maternal deaths. The World Health Organization recommends oxytocin as the first line agent to prevent hemorrhage during cesarean delivery. However, some randomized controlled trials suggest that other uterotonics are superior.

OBJECTIVE

We conducted a network meta-analysis comparing the ability of pharmacologic agents to reduce blood loss and minimize the need for additional uterotonics during cesarean delivery.

DATA SOURCES

We searched the Cochrane Central Register of Controlled Trials, Embase, and MEDLINE databases from inception to May 2020.

STUDY ELIGIBILITY CRITERIA

We included randomized controlled trials that compared oxytocin, carbetocin, misoprostol, ergometrine, carboprost, or combinations of these in the prevention of postpartum hemorrhage during cesarean delivery.

METHODS

We performed a systematic review followed by an NMA in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Quality of the evidence was assessed with the Confidence in Network Meta-Analysis approach and Grading of Recommendations, Assessment, Development and Evaluations tool within the summary of findings table. Our primary outcomes were the estimated blood loss and need for additional uterotonics. Secondary outcomes included nausea and postpartum hemorrhage of >1000 mL. We performed sensitivity analyses to explore the influence of surgical context and oxytocin administration strategy.

RESULTS

A total of 46 studies with 7368 participants were included. Of those, 21 trials (6 agents and 3665 participants) formed the "estimated blood loss" network and, considering the treatment effects, certainty in the evidence, and surface under the cumulative ranking curve scores, carbetocin was assessed to probably be superior to oxytocin, but only in reducing the estimated blood loss by a clinically insignificant volume (54.83 mL; 95% confidence interval, 26.48-143.78). Misoprostol, ergometrine, and the combination of oxytocin and ergometrine were assessed to probably be inferior, whereas the combination of oxytocin and misoprostol was assessed to definitely be inferior to oxytocin. A total of 37 trials (8 agents and 6193 participants) formed the "additional uterotonic" network and, again, carbetocin was assessed to probably be superior to oxytocin, requiring additional uterotonics 185 (95% confidence interval, 130-218) fewer times per 1000 cases. Oxytocin plus misoprostol, oxytocin plus ergometrine, and misoprostol were assessed to probably be inferior, whereas carboprost, ergometrine, and the placebo were definitely inferior to oxytocin. For both primary outcomes, oxytocin administration strategies had a higher probability of being the best uterotonic, if initiated as a bolus.

CONCLUSION

Carbetocin is probably the most effective agent in reducing blood loss and the need for additional uterotonics. Oxytocin appears to be more effective when initiated as a bolus.

Carbetocin versus oxytocin following vaginal and Cesarean delivery: a before-after study

PURPOSE

A nationwide shortage of oxytocin in Canada resulted in a temporary switch from oxytocin to carbetocin for all postpartum women at our institution. This change offered a unique opportunity to conduct a pragmatic comparative assessment of the efficacy of carbetocin and oxytocin.

METHODS

In a retrospective before-after study, we reviewed the medical records from 641 women in the carbetocin group and 752 women in the oxytocin group . The standard carbetocin dosing was 100 µg iv following vaginal and intrapartum Cesarean delivery, while for elective Cesarean delivery it was 50 µg, with an additional 50 µg if required. The standard oxytocin dosing was 5 IU iv followed by 2.4 IU·hr^-1 for four to six hours after vaginal delivery, while for Cesarean delivery it was 1-3 IU iv, three minutes apart, up to 10 IU if required, followed by the same maintenance. In both modalities of delivery, if uterine tone was suboptimal, the maintenance dose of oxytocin could be increased to 4.8 IU·hr^-1. In both groups, additional uterotonics were used as required. The primary outcome was the need for additional uterotonics. Secondary outcomes included estimated and calculated blood loss, the occurrence of postpartum hemorrhage, and the need for blood transfusion.

RESULTS

The incidence of additional uterotonic use was not different between the carbetocin and oxytocin groups (12.0% vs 8.8%; P = 0.05; odds ratio, 1.39; 95% confidence interval, 0.97 to 2.00). The incidence of postpartum hemorrhage was higher in the carbetocin group than in the oxytocin group (10.3% vs 6.6%; P = 0.01). Blood transfusion was more common in the carbetocin group (1.4% vs 0.3%; P = 0.02).

CONCLUSION

There was no difference in the use of additional uterotonics when carbetocin or oxytocin were used in a cohort of women undergoing vaginal deliveries and both elective and emergency Cesarean deliveries.

A survey of anaesthetists on uterotonic usage practices for elective caesarean section in Australia and New Zealand

Prophylactic administration of uterotonics ensures adequate uterine contraction at elective caesarean section to prevent substantial haemorrhage. Royal College of Obstetricians and Gynaecologists guidelines advise the administration of oxytocin 5 IU as a 'slow bolus' but there are variations in clinical practice. This study aimed to determine the beliefs and uterotonic usage practices at elective caesarean section by surveying anaesthetist members of the Obstetric Anaesthesia Special Interest Group in Australia and New Zealand. Questionnaires were emailed to Obstetric Anaesthesia Special Interest Group members and the response rate was 33%, with analysis of 279 completed reports. Oxytocin was the most commonly used first-line uterotonic, but extensive variation in oxytocin bolus use was identified. Thirty-eight percent of anaesthetists routinely administered Royal College of Obstetricians and Gynaecologists guideline-recommended 5 IU, whereas 38% favoured low dose (<5 IU), 10% high dose (≥10 IU) oxytocin, and 13% carbetocin (100 µg). More than 50% felt the evidence was weak for guideline-recommended 5 IU. Wide variation in the duration of oxytocin administration was also identified. Fifty-eight percent of anaesthetists routinely gave follow-up oxytocin infusions, most commonly at 40 IU over four hours, but there was significant variation in the dosage (10-40 IU) and administration duration (one hour to ≥six hours). In conclusion, there is significant variation in oxytocin usage practices at elective caesarean section among Australian and New Zealand anaesthetists. This variation may be due to a lack of strong evidence to guide practice. This emphasises the need for high quality trials in this clinically important area.

Carbetocin for the prevention of post-partum hemorrhage after vaginal birth: a real-world application

OBJECTIVE

To compare maternal outcomes using Carbetocin versus Oxytocin for the active management of the third stage of labor, given a temporary national shortage of Oxytocin.

METHODS

We conducted a retrospective observational study on a cohort of 866 women with vaginal deliveries at our center, >36 weeks of gestation, between November 2018 and March 2019. During the shortage period, each woman received a single slow intravenous injection of Carbetocin 100 µg at delivery of the anterior shoulder, rather than Oxytocin 5 UI, as postpartum hemorrhage prophylaxis. 146 (16.9%) patients received Carbetocin versus 720 (83.1%) receiving Oxytocin. The outcomes were rates of postpartum hemorrhage, severe postpartum hemorrhage, and placental retention.

RESULTS

Incidence rates of placental retention and postpartum hemorrhage were 4.9% and 9.4% respectively. Placenta retention was significantly more likely following Carbetocin administration (adjusted odds ratio 2.5; 95% confidence interval 1.2-5.0). Postpartum hemorrhage rates were not significantly different (adjusted odds ratio 1.1; 95% confidence interval 0.6-2.1), as were severe postpartum hemorrhage rates (adjusted odds ratio 0.7; 95% confidence interval 0.2-2.2).

CONCLUSION

Carbetocin is as effective as Oxytocin for postpartum hemorrhage prevention. However, we would reserve it for use after placental delivery due to the increased retention rates.

Refractory uterine atony: still a problem after all these years

Postpartum hemorrhage is a leading cause of maternal morbidity and mortality, and uterine atony is the leading cause of postpartum hemorrhage. Risk factors for uterine atony include induced or augmented labor, preeclampsia, chorio-amnionitis, obesity, multiple gestation, polyhydramnios, and prolonged second stage of labor. Although a risk assessment is recommended for all parturients, many women with uterine atony do not have risk factors, making uterine atony difficult to predict. Oxytocin is the first-line drug for prevention and treatment of uterine atony. It is a routine component of the active management of the third stage of labor. An oxytocin bolus dose as low as 1 IU is sufficient to produce satisfactory uterine tone in almost all women undergoing elective cesarean delivery. However, a higher bolus dose (3 IU) or infusion rate is recommended for women undergoing intrapartum cesarean delivery. Carbetocin, available in many countries, is a synthetic oxytocin analog with a longer duration than oxytocin that allows bolus administration without an infusion. Second line uterotonic agents include ergot alkaloids (ergometrine and methylergonovine) and the prostaglandins, carboprost and misoprostol. These drugs work by a different mechanism to oxytocin and should be administered early for uterine atony refractory to oxytocin. Rigorous studies are lacking, but methylergonovine and carboprost are likely superior to misoprostol. Currently, the choice of second-line agent should be based on their adverse effect profile and patient comorbidities. Surgical and radiologic management of uterine atony includes uterine tamponade using balloon catheters and compression sutures, and percutaneous transcatheter arterial embolization.

The Effect of Carbetocin Dose on Transmural Dispersion of Myocardial Repolarization in Healthy Parturients Scheduled for Elective Cesarean Delivery Under Spinal Anesthesia: A Prospective, Randomized Clinical Trial

BACKGROUND

QT interval prolongation is associated with torsade de pointes but remains a poor predictor of drug torsadogenicity. Increased transmural dispersion of myocardial repolarization (TDR), measured as the time interval between the peak and end of the T wave (Tp-e), is a more reliable predictor. Carbetocin is recommended as an uterotonic in patients undergoing cesarean delivery (CD), but its effect on Tp-e is unknown. We evaluated the effect of carbetocin dose on Tp-e and Bazett-corrected QT intervals (QTc) during elective CD under spinal anesthesia.

METHODS

On patient consent, 50 healthy parturients undergoing elective CD with a standardized spinal anesthetic and phenylephrine infusion were randomized to receive an intravenous (IV) bolus of carbetocin 50 µg (C50) or 100 µg (C100) via an infusion pump over 1 minute. A 12-lead electrocardiogram (ECG) was obtained at baseline, 5 minutes after spinal anesthesia, then 5 and 10 minutes after carbetocin administration. A cardiologist blinded to group and timing of ECGs measured QTc and Tp-e using Emori's criteria. Primary outcome was the change in Tp-e at 5 minutes after carbetocin administration between the C50 and C100 groups and within each group compared to baseline values. Secondary outcomes included occurrence of arrhythmias, changes in QTc at 5 and 10 minutes after carbetocin, changes in both QTc and Tp-e after spinal anesthesia compared to baseline between and within groups.

RESULTS

Data from 41 parturients with a mean (standard deviation [SD]) age of 39.0 (0.7) years and weight of 75.0 (12.0) kg were analyzed. Between groups, at 5 minutes after carbetocin administration, Tp-e in C100 was 4.1 milliseconds longer compared to C50 (95% confidence interval [CI], 0.8-7.5; P = .01). Within groups, at 5 minutes after carbetocin administration, C50 did not significantly increase Tp-e compared to baseline (mean difference [MD] 1.9 milliseconds; 95% CI, -0.95 to 4.81 milliseconds; P = .42) but C100 did (MD 5.1 milliseconds; 95% CI, 2.1-8.1; P = .003). QTc increased significantly within C50 and C100 groups at 5 and 10 minutes after carbetocin administration (all P < .001), with no between-group differences. There were no arrhythmias.

CONCLUSIONS

Tp-e was unaffected by C50 IV given after CD in healthy parturients under spinal anesthesia, but minimally prolonged by C100. The increase in QTc after carbetocin administration was statistically significant, but with no apparent dose-dependent effect. The minimal Tp-e prolongation at the higher dose is unlikely to have any clinically significant impact on TDR and therefore the risk of inducing torsade de pointes is low.

Minimally Invasive Hemodynamic Assessment during Obstetric Hysterectomy for Invasive Placentation with Epidural Anesthesia

Background

The present study aimed to describe the evolution of hemodynamic parameters over time of patients with invasive placentation during their third trimester who were delivered via cesarean section and subsequently underwent obstetric hysterectomy under epidural anesthesia.

Methods

A prospective, descriptive, longitudinal, 11-month cohort study of 43 patients aged between 18 and 37 years who presented with invasive placentation. Minimal invasive monitoring was placed before the administration of epidural anesthesia for hemodynamic parameter tracking during the cesarean section. After delivery, the patients underwent an obstetric hysterectomy. Blood loss, hemodynamic parameters, and coagulation were managed via goal-directed therapy. Parameters were compared via repeated measures ANOVA and effect size estimation (Cohen's d).

Results

The mean age of the patients was 29.2 ± 3.4 years and was moderately overweight. They had minor cardiac index variance (P=NS, no significance), vascular systemic resistance index (NS), heart rate (P=NS), and median arterial pressure (P=NS). Differences were observed in the stroke volume index (P=0.015) due to moderately higher values (d = 0.3, P=0.016) in the middle of the surgery. Patients had lower cardiac index (d = -0.36, NS) and cardiac workload requirements (d = -0.29, P=0.034) toward the completion of surgery.

Conclusion

Patients who are in their third trimester and who subsequently underwent obstetric hysterectomy under epidural anesthesia had modest surgical hemodynamic variance and reduced cardiac workload requirements toward the end of the surgery.

Carbetocin compared with oxytocin in non-elective Cesarean delivery: a systematic review, meta-analysis, and trial sequential analysis of randomized-controlled trials

PURPOSE

Carbetocin has been shown to reduce the requirement for additional uterotonics in women exclusively undergoing elective Cesarean delivery (CD). The aim of this review was to determine whether this effect could also be demonstrated in the setting of non-elective CD.

METHODS

Medline, Embase, CINAHL, Web of Science and Cochrane databases were searched for randomized-controlled trials (RCTs) in any language comparing carbetocin to oxytocin. Studies with data on women undergoing non-elective CD, where carbetocin was compared with oxytocin, were included. The primary outcome was the need for additional uterotonics. Secondary outcomes included incidence of blood transfusion, estimated blood loss (mL), incidence of postpartum hemorrhage (PPH; > 1000 mL) and mean hemoglobin drop (g·dL^-1 RESULTS: Five RCTs were included, with a total of 1,214 patients. The need for additional uterotonics was reduced with carbetocin compared with oxytocin (odds ratio, 0.30; 95% CI, 0.11 to 0.86; I², 90.60%). Trial sequential analysis (TSA) confirmed that the information size needed to show a significant reduction in the need for additional uterotonics had been exceeded. No significant differences were shown with respect to any of the secondary outcomes, but there was significant heterogeneity between the studies.

CONCLUSIONS

Carbetocin reduces the need for additional uterotonics in non-elective CD compared with oxytocin. TSA confirmed that this analysis was appropriately powered to detect the pooled estimated effect. Further trials utilizing consistent core outcomes are needed to determine an effect on PPH.

TRIAL REGISTRATION

PROSPERO CRD42019147256, registered 13 September 2019.

What does basic science tell us about the use of uterotonics?

Pharmacotherapy with uterotonics remains the mainstay of the management for post-partum haemorrhage. Clinical studies evaluating the efficacy of these drugs are fraught with confounders, which may influence uterine contractility and blood loss. For this reason, a range of techniques have been developed to study myometrial function in vitro, allowing for the comparison of various drugs in a controlled-simulated physiological environment. In this review, we focus on the main classes of uterotonic drugs and outline their molecular and physiological basis of action. We explore the evidence related to appropriate drug dosing and relative efficacy, and compare the evidence gleaned from clinical and in vitro studies. We discuss the mechanism of oxytocin desensitisation and how basic science has helped us understand this phenomenon. We also discuss the in vitro research findings for each of the main classes of uterotonic drugs that have contributed to an improved understanding of the management of post-partum haemorrhage and, ultimately, better care for mothers.

Efficacy and safety of carbetocin given as an intravenous bolus compared with short infusion for Caesarean section - double-blind, double-dummy, randomized controlled non-inferiority trial

Background

Carbetocin is a synthetic oxytocin-analogue, which should be administered as bolus according to manufacturer's recommendations. A higher speed of oxytocin administration leads to increased cardiovascular side-effects. It is unclear whether carbetocin administration as short infusion has the same efficacy on uterine tone compared with bolus administration and whether haemodynamic parameters differ.

Methods

In this randomized, double-blind, non-inferiority trial, women undergoing planned or unplanned Caesarean section (CS) under regional anaesthesia received a bolus and a short infusion, only one of which contained carbetocin 100 mcg (double dummy). Obstetricians quantified uterine tone two, three, five and 10 min after cord-clamping by manual palpation using a linear analogue scale from 0 to 100. We evaluated whether the lower limit of the 95% CI of the difference in maximum uterine tone within the first five min after cord-clamping did not include the pre-specified non-inferiority limit of -10.

Results

Between December 2014 and November 2015, 69 patients were randomized to receive carbetocin as bolus and 71 to receive it as short infusion. Maximal uterine tone was 89 in the bolus and 88 in the short infusion group (mean difference -1.3, 95% CI -5.7 to 3.1). Bp, calculated blood loss, use of additional uterotonics, and side-effects were comparable.

Conclusions

Administration of carbetocin as short infusion does not compromise uterine tone and has similar cardiovascular side-effects as a slow i.v. bolus. In accordance with current recommendations for oxytocin, carbetocin can safely be administered as short -infusion during planned or unplanned CS.

Clinical trial registration

ClinicalTrials.gov NCT02221531 and www.kofam.ch SNCTP000001197.

Uterotonic drug usage in Canada: a snapshot of the practice in obstetric units of university-affiliated hospitals

OBJECTIVE

The objective of this study was to determine the pattern of uterotonic drug usage in obstetric units of university-affiliated hospitals in Canada.

METHODS

This was a prospective observational study conducted in the form of an electronic survey. The target group consisted of chiefs or directors of Obstetrics and Anaesthesia at university-affiliated hospitals across Canada. The survey was sent out between November 2016 and January 2017, using the program 'SurveyMonkey'. Data on institutional obstetric practices and usage of uterotonic agents were collected.

RESULTS

The survey was sent to 92 obstetricians and anesthesiologists from 46 institutions, of which 33 clinicians from 24 institutions responded. About 65% of clinicians were unaware of the rate of postpartum hemorrhage in their institution. The first-line agent for vaginal deliveries was reported as oxytocin by 94% and carbetocin by 6% of physicians. For women at low-risk for postpartum hemorrhage when undergoing cesarean deliveries (CD), 66% reported oxytocin as the first-line uterotonic, while 34% reported carbetocin. For CDs at high-risk of postpartum hemorrhage, 60% of physicians reported oxytocin and 40% reported using carbetocin initially. The use of second-line uterotonics was also variable. The choice of uterotonic was mainly based on perceived efficacy and Society of Obstetricians and Gynaecologists of Canada guidelines.

CONCLUSION

There is a lack of a unified approach to the use of uterotonic drugs for postpartum hemorrhage management in Canada. To improve the management of postpartum hemorrhage due to uterine atony, an evidence-based approach to usage and consensus between obstetricians and anesthesiologists is warranted.

Adverse Effects of Carbetocin versus Oxytocin in the Prevention of Postpartum Haemorrhage after Caesarean Section: A Randomized Controlled Trial

Purpose

To compare the incidence of nausea, vomiting, and arterial hypotension between carbetocin and oxytocin to prevent haemorrhage after caesarean section (CS).

Methods

A randomized controlled trial in term pregnant women undergoing planned CS. Groups were randomized to carbetocin or oxytocin. Blood pressure (BP), heart rate, presence of nausea/vomitus, and need for vasopressors were evaluated throughout surgery. Preoperative and postoperative haemoglobin and haematocrit levels were compared.

Results

Fifty-eight women were randomized (carbetocin n = 32; oxytocin n = 26). Both medications had hypotensive effect, difference in BP for carbetocin versus oxytocin: systolic (14.4 ± 2.4 mmHg versus 8.5 ± 1.8 mmHg); diastolic (7.8 ± 1.6 mmHg versus 8.9 ± 3.0 mmHg) without significant difference between the drugs (p = 0.1 and p = 0.7). Both groups had similar needs for vasopressors. The presence of nausea was not rare, but the difference was not statistically significant (p = 0.4). Average blood loss was slightly lower in the carbetocin group but not statistically significant (p = 0.8).

Conclusion

In planned CS, a possible clinical significant lower incidence of nausea after carbetocin was noted but this was not statistically significant. There were no differences regarding BP, heart rate, the need for vasopressor, and blood loss. The study was registered in the International Journal of Clinical Trials (ISRCTN 95504420, 2/2017).

The association between the time from oxytocin cessation during labour to Cesarean delivery and postpartum blood loss: a retrospective cohort study

PURPOSE

Prolonged exposure to oxytocin during augmentation of labour is associated with uterine atony and an increased risk of postpartum hemorrhage (PPH) due to oxytocin receptor desensitization. Cessation of oxytocin infusion during labour may facilitate recovery of oxytocin receptor function, which then helps to restore myometrial contractility and decrease postpartum blood loss. We examined the association between oxytocin recovery interval, i.e., the time from discontinuing oxytocin to Cesarean delivery (CD) for labour arrest, and blood loss.

METHODS

This retrospective cohort study included women who underwent CD for labour arrest following oxytocin-augmented labour from July 1, 2013 to July 19, 2015 at our institution. Data were collected on patient demographics, labour and delivery characteristics, oxytocin induction and augmentation, recovery interval, and PPH risk factors. The primary outcome was estimated blood loss (EBL), calculated using the hematocrit variation method.

RESULTS

Data on 490 women were analyzed. The mean (standard deviation) EBL was 1,341 (577) mL; the amount of oxytocin administered during labour was 6,447 (6,868) mU, and the oxytocin recovery interval was 99 (65) min. Every ten-minute increase in the recovery interval was associated with a 10-mL decrease in EBL (95% confidence interval [CI], -18 to -3; P = 0.009). Morbidly obese women had a significantly higher EBL than those with a body mass index < 40 kg·m^-2 (mean difference, 572 mL; 95% CI, 382 to 762; P < 0.001). The amount and duration of oxytocin administered during labour, but not the oxytocin recovery interval, was associated with the use of additional interventions to control PPH (P = 0.005).

CONCLUSION

Our study shows that an increase in the oxytocin recovery interval is associated with a decrease in blood loss at CD in women with oxytocin augmented labour. These data support discontinuing the oxytocin infusion as soon as the decision is made to proceed with CD for labour arrest, particularly in morbidly obese women.

Postpartum haemorrhage: prevention and treatment

INTRODUCTION

Postpartum hemorrhage (PPH) is one of the leading causes of maternal death and severe maternal morbidity worldwide and strategies to prevent and treat PPH vary among international authorities. Areas covered: This review seeks to provide a global overview of PPH (incidence, causes, risk factors), prevention (active management of the third stage of labor and prohemostatic agents), treatment (first, second and third-line measures to control PPH), by also underlining recommendations elaborated by international authorities and using algorithms. Expert commentary: When available, oxytocin is considered the drug of first choice for both prevention and treatment of PPH, while peripartum hysterectomy remains the ultimate life-saving procedure if pharmacological and resuscitation measures fail. Nevertheless, the level of evidence for preventing and treating PPH is globally low. The emergency nature of PPH makes randomized controlled trials (RCT) logistically difficult. Population-based observational studies should be encouraged as they can usefully strengthen the evidence base, particularly for components of PPH treatment that are difficult or impossible to assess through RCT.

[Clinical and pharmacological procedures for the prevention of postpartum haemorrhage in the third stage of labor]

OBJECTIVES

To describe the clinical and pharmacological procedures for the prevention of Postpartum Haemorrhage (PPH).

MATERIALS AND METHODS

We searched the Medline and the Cochrane Library (1st December 2004 to 1st March 2014) and we checked the international guidelines.

RESULTS

Vaginal birth: only the use of uterotonics reduces the incidence of PPH. Oxytocin is the treatment of choice if it is readily available (grade A). Oxytocin can be used either after the shoulders expulsion or rapidly after the placental delivery (grade B). A dose of 5 or 10IU must be administrated IV over at least 1minute or directly by an intramuscular injection (professional agreement) except in women with documented cardiovascular disease in which the duration of the IV perfusion should be over at least 5minutes (professional agreement). Mechanical procedures have no significant impact on PPH. The decision to use a collector bag is left to the medical team (professional agreement). A systematic complementary oxytocin perfusion is not recommended (professional agreement). Caesarean delivery: There is no evidence to recommend a particular type of caesarean technique to prevent PPH (professional agreement) but a lower uterine section is recommended (grade B). All types of incision expansion may be used (professional agreement). A controlled cord traction is associated with lower blood losses than manual removal of the placenta (grade B). A dose of 5 or 10IU can be injected (IV) over 1minute, and over 5minutes in women with cardiovascular disease (professional agreement). Carbetocin reduces the incidence of PPH but there is presently no inferiority study comparing oxytocin and carbetocin so that oxytocin remains the gold standard therapy to prevent PPH in C-section (professional agreement).