The ED90 of Prophylactic Oxytocin Infusion After Delivery of the Placenta During Cesarean Delivery in Laboring Compared with Nonlaboring Women

Labor Analgesia Initiation With Dural Puncture Epidural Versus Conventional Epidural Techniques: A Randomized Biased-Coin Sequential Allocation Trial to Determine the Effective Dose for 90% of Patients of Bupivacaine

BACKGROUND

The dural puncture epidural (DPE) technique has a faster onset, better sacral spread, and improved bilateral coverage when compared to the conventional epidural (EPL) technique. Whether these qualities translate into a lower bupivacaine dose to provide initial analgesia is unknown. We sought to determine the effective dose of bupivacaine to achieve initial (first 30 minutes) labor analgesia in 90% of patients (ED90) with the DPE and EPL techniques, using a biased-coin, sequential allocation method.

METHODS

A total of 100 women of mixed parity with term, singleton gestation at ≤5 cm dilation with no major comorbidities were randomized to receive a DPE or an EPL technique. An experienced anesthesiologist performed these techniques and administered an allocated dose of plain bupivacaine diluted with isotonic sterile 0.9% saline to a total volume of 20 mL via the EPL catheter. Bupivacaine doses for each subject were determined by the response of the previous subject, using a biased-coin sequential allocation method, with success defined by a numeric rating scale (NRS) < 3 at 30 minutes. Outcome assessments were performed by an investigator blinded to the technique and bupivacaine dose. Sensory and motor blockade and maternal or fetal side effects were recorded every 5 minutes for the first 30 minutes. The ED90 of bupivacaine with each technique was estimated using centered isotonic regression.

RESULTS

A total of 95 women were included in the final analysis. The ED90 of bupivacaine was estimated at 29.30 mg (90% confidence interval [CI], 28.55-31.56) with a DPE technique and 45.25 mg (90% CI, 42.80-52.03) with an EPL technique.

CONCLUSIONS

Using a biased-coin, sequential allocation method, the DPE technique requires less bupivacaine to achieve effective initial analgesia (ED90) when compared to the EPL technique.

Discontinuation of Oxytocin in the Second Stage of Labor and its Association with Postpartum Hemorrhage

OBJECTIVE

 The objective of the study was to evaluate whether patients with oxytocin discontinued during the second stage of labor (≥30 minutes prior to delivery) had a lower rate of postpartum hemorrhage (PPH) compared with those with oxytocin continued until delivery or discontinued <30 minutes prior to delivery.

STUDY DESIGN

 Retrospective cohort study was performed from August 1, 2014 to July 31, 2019. Singleton pregnancies of 24 to 42 weeks gestation were included if they reached the second stage of labor and received oxytocin during labor. Patients on anticoagulants were excluded. Patients with oxytocin discontinued ≥30 minutes prior to delivery represented STOPPED and those with oxytocin continued until delivery or discontinued <30 minutes prior to delivery represented CONTINUED. Patient data were abstracted from the electronic medical record. The primary outcome was PPH (≥1,000 mL blood loss). Univariable analyses were performed to compare groups. Multi-variable logistic regression was performed to adjust for prespecified confounders. Planned sub-group analyses by the route of delivery were performed.

RESULTS

 Of 10,421 total patients, 1,288 had oxytocin STOPPED and 9,133 had oxytocin CONTINUED. There were no significant differences in age, race, or ethnicity, body mass index, public insurance, gestational diabetes, or pregnancy-induced hypertension between STOPPED and CONTINUED. The PPH rate was 15.2 and 5.7% in STOPPED and CONTINUED, respectively (p < 0.001). After adjusting for confounders, STOPPED remained at higher odds for PPH (adjusted odds ratio 2.859, 95% confidence interval 2.394, 3.414, p < 0.001). Among cesarean deliveries only, there was no significant difference in the rate of PPH between STOPPED and CONTINUED (38.0 vs. 36.4%, respectively, p = 0.730). However, among vaginal deliveries, the rate of PPH was actually lower in STOPPED than CONTINUED (3.4 vs. 5.2%, respectively, p = 0.024).

CONCLUSION

 The rate of PPH was higher in patients with oxytocin STOPPED compared with CONTINUED. However, among vaginal deliveries, there was a significantly lower rate of PPH in STOPPED. These disparate findings may be explained by the variable impact of second-stage oxytocin on PPH as a function of delivery type.

KEY POINTS

· It is unclear if oxytocin use in the second stage of labor may independently increase the risk of hemorrhage.. · Patients with oxytocin discontinued during the second stage of labor had a higher rate of PPH.. · PPH was significantly lower among vaginal deliveries in patients with oxytocin discontinued..

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.

Oxytocin infusion dose-response to maintain uterine tone in obese elective cesarean patients: a randomized controlled trial

Background

For cesarean delivery (CD), the 90% effective dosage (ED90) of oxytocin for a first bolus has been established. It is not yet known how much oxytocin to inject into obese women undergoing elective discectomy to keep their uterine tone (UT) appropriate. We hypothesized that patients who are overweight need a greater dose of oxytocin infusion; thus, we aimed to determine how the dose-response curve for oxytocin infusion changes following an initial 1 international unit (IU) bolus in obese women undergoing elective CD.

Methods

One hundred parturients with a body mass index (BMI) greater than 30 kg/m2 were randomly assigned to receive an infusion rate of 14, 18, 22, or 26 IU/h of oxytocin. When the uterine palpation is as hard as touching the forehead or tip of the nose, it is considered sufficient UT according to the criteria used by obstetricians. The median effective dose (ED50) and ED90 values were determined using probit analysis.

Results

We found the ED50 and ED90 values for the infusion dose of oxytocin were around 11.0 IU/h and 19.1 IU/h, respectively. Each group had a different number of parturients who needed rescued oxytocin: 14 IU/h for six, 18 IU/h for three, one for 22 IU/h, and none for 26 IU/h. The correlation between the frequency of rescued oxytocin administration and the amount of oxytocin infusion needed to avoid uterine atony was statistically significant (p = 0.02).

Conclusion

The present research showed that the most effective dosage of oxytocin infusion for obese parturients undergoing elective CD is 19.1 IU/h, following an initial loading dose of 1 IU. Patients with obesity should receive a greater dosage of prophylactic oxytocin, and further studies comparing patients with and without obesity (with higher BMI) are required.

Clinical Trial Registration

https://www.chictr.org.cn/showproj.html?proj=159951, identifier ChiCTR2200059582.

Weight-based versus fixed dose oxytocin infusion for preventing uterine atony during cesarean section in laboring patients: A randomized trial

OBJECTIVE

We compared efficacy of weight-based (0.4 IU/kg/h) versus fixed-dose (34 IU/h) oxytocin infusion during cesarean section.

METHODS

The oxytocin infusion in either group (n = 32 each) was initiated upon cord clamping. Primary outcome measure was adequacy of uterine tone at 4 min after initiating oxytocin infusion. Oxytocin associated side effects were also observed.

RESULTS

Significantly less oxytocin was used with the weight-based versus fixed-dose regimen (16.3 [11.2-22.4] IU vs 20.4 [15.8-26.9] IU; P = 0.036). Incidence of adequate uterine tone was clinically greater but not significantly different with the weight-based versus fixed-dose regimen (81.3% vs 71.9%; P = 0.376). The weight-based regimen was associated with clinically lesser, although not statistically significant need for rescue oxytocin (25% vs 46.9%; P = 0.068) and additional uterotonic (9.4% vs 15.6%; P = 0.708); as well as oxytocin associated side effects (hypotension [34.4% vs 46.9%; P = 0.309], nausea/vomiting [18.8% vs 40.6%; P = 0.055], and ST-T changes [0% vs 3.1%; P = 1.000]).

CONCLUSION

Weight-based oxytocin was not significantly different from the fixed-dose regimen in terms of uterotonic efficacy or associated side-effects, despite significantly lower doses being used. Use of weight-based oxytocin infusion (0.4 IU/kg/h) can be considered in clinical practice.

TRIAL REGISTRATION

Clinical Trial Registry of India (ctri.nic.in, number. CTRI/2021/01/030642).

The minimum effective dose (ED90) of prophylactic oxytocin infusion during cesarean delivery in patients with and without obesity: an up-down sequential allocation dose-response study

BACKGROUND

Obesity is associated with greater oxytocin requirement during labor induction or augmentation. There are scant data exploring the intra-operative requirement during cesarean delivery in patients with obesity, and none comparing it with those without obesity. We evaluated the minimum effective dose (ED90) of an oxytocin infusion to achieve adequate uterine tone during cesarean delivery in patients with and without obesity.

METHODS

Patients (body mass index ≥30 kg/m2 represented patients with obesity) undergoing cesarean delivery using subarachnoid block were included. This prospective dual-arm dose-finding study used a 9:1 biased sequential allocation design. Oxytocin infusion was initiated at 13 IU/h at cord clamping in the first patient of each group. Uterine tone was graded as satisfactory or unsatisfactory by the obstetrician four minutes after initiation of the infusion. The dose of oxytocin infusion for subsequent patients was determined according to the response of the previous patient in the group. Oxytocin-associated side effects were evaluated. Dose-response data for the groups was evaluated using log-logistic function and ED90 estimates derived from fitted equations using the delta method.

RESULTS

The ED90 of oxytocin was significantly higher for patients with obesity (n = 40) compared with those without obesity (n = 40) [25.7 IU/h, 95% CI 18.6 to 32.9) vs. 16.6 IU/h, 95% CI 14.9 to 18.3)]; relative ratio 1.55 [95% CI 1.09 to 2.01] (P = 0.019).

CONCLUSIONS

Patients with obesity require a higher intra-operative oxytocin infusion dose rate to achieve a satisfactorily contracted uterus after fetal delivery when compared with patients without obesity.

Oxytocin is not associated with postpartum hemorrhage in labor augmentation in a retrospective cohort study in the United States

BACKGROUND

Previous studies reported conflicting results on the relationship between oxytocin use for labor augmentation and the risk of postpartum hemorrhage, probably because it is rather challenging to disentangle oxytocin use from labor dystocia.

OBJECTIVE

This study aimed to investigate the independent association between oxytocin use for augmentation and the risk of postpartum hemorrhage by using advanced statistical modeling to control for labor patterns and other covariates.

STUDY DESIGN

We used data from 20,899 term, cephalic, singleton pregnancies of patients with spontaneous onset of labor and no previous cesarean delivery from Intermountain Healthcare in Utah in the Consortium on Safe Labor. Presence of postpartum hemorrhage was identified on the basis of a clinical diagnosis. Propensity scores were calculated using a generalized linear mixed model for oxytocin use for augmentation, and covariate balancing generalized propensity score was applied to obtain propensity scores for the duration and total dosage of oxytocin augmentation. A weighted generalized additive mixed model was used to depict dose-response curves between the duration and total dosage of oxytocin augmentation and the outcomes. The average treatment effects of oxytocin use for augmentation on postpartum hemorrhage and estimated blood loss (mL) were assessed by inverse probability weighting of propensity scores.

RESULTS

The odds of both postpartum hemorrhage and estimated blood loss increased modestly when the duration and/or total dosage of oxytocin used for augmentation increased. However, in comparison with women for whom oxytocin was not used, oxytocin augmentation was not clinically or statistically significantly associated with estimated blood loss (6.5 mL; 95% confidence interval, 2.5-10.3) or postpartum hemorrhage (adjusted odds ratio, 1.02; 95% confidence interval, 0.82-1.24) when rigorously controlling for labor pattern and potential confounders. The results remained consistent regardless of inclusion of women with an intrapartum cesarean delivery.

CONCLUSION

The odds of postpartum hemorrhage and estimated blood loss increased modestly with increasing duration and total dosage of oxytocin augmentation. However, in comparison with women for whom oxytocin was not used and after controlling for potential confounders, there was no clinically significant association between oxytocin use for augmentation and estimated blood loss or the risk of postpartum hemorrhage.

Oxytocin infusion for maintenance of uterine tone under prophylactic phenylephrine infusion for prevention of post-spinal hypotension in cesarean delivery: a prospective randomised double-blinded dose-finding study

BACKGROUND

Prior studies have shown that, when administered as an intravenous bolus to prevent uterine atony, prophylactic phenylephrine infusion increased the dose requirement of oxytocin and second-line uterotonics. For the prevention of uterine atony, oxytocin should be delivered by continuous infusion. Here, we aimed to determine the ED50 and ED90 parameters (the effective doses for 50 and 90% patients without uterine atony) of oxytocin for co-infusion with prophylactic phenylephrine during cesarean delivery.

METHODS

In this prospective randomized double-blinded dose-finding study, one hundred patients were divided into four groups to receive 2.5, 5.0, 7.5, or 10 IU/h oxytocin infusion, after the umbilical cord was clamped during the study period. The uterine tone was evaluated and defined as either adequate or inadequate. Probit regression analysis was applied to calculate the ED50 and ED90 of oxytocin infusion. Uterine tone, the percentage of patients who needed additional oxytocin bolus, second-line uterotonics, side effects, estimated blood loss, and neonatal outcomes were monitored.

RESULTS

The estimated ED50 and ED90 values of the oxytocin infusion doses for the prevention of uterine atony were 1.9 IU/h (95% CI -4.6-3.8) IU/h and 9.3 IU/h (95% CI 7.3-16.2) IU/h, respectively. Across groups, there was a significant linear trend between the infusion dose and the percentage of patients who required additional oxytocin (p-value = 0.002). No differences were observed in the incidence of side effects and neonatal outcomes.

CONCLUSION

Under the conditions of this study, the ED90 of oxytocin infusion for the prevention of uterine atony was 9.3 IU/h, which is higher than the current recommendation. This finding is helpful for clinical practice, because of the routine use of phenylephrine in cesarean delivery. Further studies are needed to determine the appropriate initial bolus of oxytocin after neonatal delivery.

TRIAL REGISTRATION

The study was registered on the Chinese Clinical Trial Register (register no. ChiCTR2200059556 ).

Care for the Obstetric Patient with Complex Cardiac Disease

The prevalence of cardiac disease-related maternal morbidity and mortality is on the rise in the United States. To ensure safe management of pregnancy in patients with cardiovascular disease, pre-delivery evaluation by a multidisciplinary Pregnancy Heart Team should occur. Appropriate anesthetic, cardiac, and obstetric care are essential. Risk stratification tools evaluate the etiology and severity of cardiovascular disease to determine the appropriate hospital type and location for delivery and anesthetic management. Intrapartum hemodynamic monitoring may need to be intensified, and neuraxial analgesia and anesthesia are generally appropriate. The anesthesiologist must be prepared for obstetric and cardiac emergencies.

A Monte Carlo simulation study comparing the up and down, biased-coin up and down and continual reassessment methods used to estimate an effective dose (ED95 or ED90) in anaesthesiology research

Background

Dose-finding studies in anaesthesiology aim to target the effective dose (ED) of an anaesthetic agent in a specific population. The common dose-finding designs used are the up and down method (UDM), the biased-coin up and down (BCD), and the continual reassessment method (CRM). Although the advantages of CRM over the UDM and BCD methods have been described in the statistical literature in terms of precision and direct estimation of ED, CRM may also offer attractive properties from an ethical point of view.

Methods

Based on Monte Carlo simulations, this article aims to compare the three methods with regard to 1) their ability to find as close an estimate as possible for the ED95 or ED90 and 2) the total number of patients needed to treat and the number of failures.

Results

In contrast to BCD and UDM, CRM does find an estimate for ED95 and ED90. UDM underestimates both ED95 and ED90. BCD is close to the targeted EDs when the starting dose does not exceed the ED of interest, otherwise it overestimates it. CRM with cohorts of two patients is closest to the ED of interest independently of the starting doses. CRM requires between 20 and 50 observations, UDM should include 90 patients, and BCD 100 or 60 observations. Lastly, CRM is associated with fewer failures, compared with BCD and UDM.

Conclusions

Based on Monte Carlo simulations, our work suggests that the UDM is not an adequate dose-finding method because it underestimates the ED of interest. Compared with BCD, CRM offers the advantages of being more efficient, requires fewer patients to be included, and is associated with fewer failures.

Minimum effective dose of oxytocin bolus during the caesarean section for patients at high vs low risk of uterine atony: A non-randomized, dual-arm, dose-finding prospective trial

Background and Aims

There are scanty data for oxytocin dose in patients at high risk of uterine atony. We aimed to compare the effective dose (ED) 90 of oxytocin for adequate uterine tone during the caesarean section in patients at high-risk vs low-risk uterine atony.

Methods

This dose-finding study was undertaken after ethical approval in non-labouring women aged >18 years with pre-defined risk factors for uterine atony (high-risk group) vs those without such factors (low-risk group) (n = 39 each). Starting dose of oxytocin in the first patient of low-risk and high-risk groups was 1 and 3 IU, respectively. Achieving adequate uterine tone at 3 min of oxytocin bolus was designated 'success', while inadequate tone constituted 'failure'. If the response was 'failure', the dose of oxytocin was increased for the next patient by 0.5 or 0.2 IU (high- and low-risk groups, respectively). In case of a successful response, the dose for the next patient was decreased with a probability of 1/9 using the same dosing intervals or otherwise kept unchanged.

Results

The ED90 (95% CI) of oxytocin bolus was 4.7 (3.3-6.0) IU for the high-risk group and 2.2 (1.3-3.2) IU for the low-risk group (P = 0.044). Oxytocin-associated tachycardia (P = 0.247) and hypotension (P = 0.675) were clinically greater for the high-risk vs low-risk group but statistically similar.

Conclusion

Non-labouring patients with high-risk factors for uterine atony require a greater dose of initial oxytocin bolus to achieve adequate uterine tone during the caesarean section compared to those without risk factors.

The optimal oxytocin infusion rate for preventing uterine atony during cesarean delivery in elderly parturients with prior history of cesarean delivery

Background: An estimate of 90% effective dose (ED90) of oxytocin infusion has already been proved effective in non-laboring parturients. However, the requirements of oxytocin for elderly parturients with prior history of cesarean delivery (CD) may be higher. The aim of this study was to find the optimum oxytocin infusion rate for preventing uterine atony during CD in elderly parturients with prior history of CD. Method: We performed a randomized, double-blinded study in 120 healthy elderly parturients with prior history of CD scheduled for elective CD under combined spinal-epidural (CSE) anesthesia. Participants were treated with oxytocin infusion randomly at the rates of 0, 4, 8, 12, 16, or 20 IU h-1 after the delivery of infants. Following oxytocin administration, a blinded obstetrician evaluated the uterine tone (UT), verbally describing it using numerical scales (0-10: 0, no UT; 10, optimal UT) as either adequate or inadequate at the time intervals of 3, 6, and 9 min. Maternal adverse effects, requirements for additional uterotonic agents, delivery-placenta delivery time (PD), and estimated blood loss (EBL) were recorded. Results: The 50% effective dose (ED50) and 90% effective dose (ED90) of oxytocin infusion were 14.6 IU h-1 (95% confidence interval 12.0-18.4 IU h-1) and 27.7 IU h-1 (95% confidence interval 22.5-39.4 IU h-1), respectively. As the rate of infusion was increased in parturients, the rescue oxytocin dose and delivery-PD time were decreased. Parturients who received 0 IU h-1 oxytocin at 3, 6, and 9 min obtained lower UT scores than those who received 16 and 20 IU h-1 oxytocin (p < 0.05, respectively). No significant differences were observed among groups in EBL and maternal adverse effects. Conclusion: The infusion rate of oxytocin at 14.57 and 27.74 IU h-1 produces adequate UT in 50% and 90% of elderly parturients with prior history of CD, respectively. An oxytocin infusion rate of 27.7 IU h-1 is suggested to be the optimal dose for preventing uterine atony during CD in elderly parturients with prior history of cesarean delivery. Clinical Trial Registration: [https://www.chictr.org.cn/bin/project/edit?pid=62489], Identifier: [ChiCTR2000038891].

Effect of an oxytocin protocol on secondary uterotonic use in patients undergoing Cesarean delivery

PURPOSE

Protocol-driven oxytocin regimens can reduce oxytocin administration compared with a nonprotocol free-flow continuous infusion. Our aim was to compare secondary uterotonic use between a modified "rule of threes" oxytocin protocol and a free-flow continuous oxytocin infusion after Cesarean delivery.

METHODS

We conducted a retrospective before-and-after study to compare patients who underwent Cesarean delivery between 1 January 2010 and 31 December 2013 (preprotocol) with patients who underwent Cesarean delivery between 1 January 2015 and 31 August 2017 (postprotocol). The preprotocol group received free-flow oxytocin administration and the postprotocol group received oxytocin according to a modified rule of threes algorithm. The primary outcome was secondary uterotonic use and the secondary outcomes included blood transfusion, hemoglobin value < 8 g·dL-1, and estimated blood loss.

RESULTS

In total, 4,010 Cesarean deliveries were performed in 3,637 patients (2,262 preprotocol and 1,748 postprotocol). The odds of receiving secondary uterotonic drugs were increased in the postprotocol group (odds ratio [OR], 1.33; 95% confidence interval [CI], 1.04 to 1.70; P = 0.02). Patients in the postprotocol group were less likely to receive a blood transfusion. Nevertheless, the two groups were similar for the composite end point of transfusion or hemoglobin < 8 g·dL-1 (OR, 0.86; 95% CI, 0.66 to 1.11; P = 0.25). The odds of an estimated blood loss greater than 1,000 mL were reduced in the postprotocol group (OR, 0.64; 95% CI, 0.50 to 0.84; P = 0.001).

CONCLUSIONS

Patients in the modified rule of threes oxytocin protocol group were more likely to receive a secondary uterotonic than those in the preprotocol group. Estimated blood loss and transfusion outcomes were similar.

Anesthetic Care of the Pregnant Patient With Cardiovascular Disease: A Scientific Statement From the American Heart Association

The pregnancy-related mortality rate in the United States is excessively high. The American Heart Association is dedicated to fighting heart disease and recognizes that cardiovascular disease, preexisting or acquired during pregnancy, is the leading cause of maternal mortality in the United States. Comprehensive scientific statements from cardiology and obstetrics experts guide the treatment of cardio-obstetric patients before, during, and after pregnancy. This scientific statement aims to highlight the role of specialized cardio-obstetric anesthesiology care, presenting a systematic approach to the care of these patients from the anesthesiology perspective. The anesthesiologist is a critical part of the pregnancy heart team as the perioperative physician who is trained to prevent or promptly recognize and treat patients with peripartum cardiovascular decompensation. Maternal morbidity is attenuated with expert anesthesiology peripartum care, which includes the management of neuraxial anesthesia, inotrope and vasopressor support, transthoracic echocardiography, optimization of delivery location, and consideration of advanced critical care and mechanical support when needed. Standardizing the anesthesiology approach to patients with high peripartum cardiovascular risk and ensuring that cardio-obstetrics patients have access to the appropriate care team, facilities, and advanced cardiovascular therapies will contribute to improving peripartum morbidity and mortality.

Weight-based oxytocin infusion for preventing uterine atony during caesarean delivery in non-labouring patients: A dose-response study

Postpartum haemorrhage remains a significant cause of maternal morbidity and mortality with the commonest reason being uterine atony. For prevention of uterine atony during caesarean delivery, oxytocin is advocated as a first line drug. There is however no published data regarding utility of a weight-based oxytocin infusion. The present study evaluated dose-response relationship for oxytocin infusion when used as weight-based regimen. A total of 55 non-labouring patients without risk factors for uterine atony and scheduled for caesarean delivery under spinal anaesthesia were enrolled. Randomization was done to receive oxytocin infusion in a dose of 0.1, 0.15, 0.2, 0.25 or 0.3 IU kg^-1  h^-1 (n = 11 each), initiated at the time of cord clamping and continued until the end of surgery. Successful outcome was defined as attaining an adequate uterine response at 4 min of initiation of infusion and maintained till end of surgery. Oxytocin associated hypotension, tachycardia, ST-T changes, nausea/vomiting, flushing and chest pain were also observed. A significant linear trend for adequate intraoperative uterine tone was seen with increasing dose of weight-based oxytocin infusion (P < 0.001). The effective dose in 90% population (ED90) was 0.29 IU kg^-1  h^-1 (95% CI = 0.25-0.42). Amongst the oxytocin associated side effects, a significant linear trend was seen between increasing dose of oxytocin infusion and hypotension as well as nausea/vomiting (p = 0.016 and 0.023 respectively). Thus, oxytocin infusion during caesarean delivery may be used as per the patient's body weight.

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

Oxytocin infusion rates for maintaining uterine tone during non-elective cesarean section in laboring patients: a randomized, controlled trial

PURPOSE

Oxytocin infusions for uterine tone maintenance are recommended following initial low oxytocin doses during cesarean section. Very limited literature is available on the optimal infusion rates in laboring patients who have been earlier exposed to oxytocin.

METHODS

105 patients, having received oxytocin for induction/augmentation of labor, received oxytocin infusions at rates of 2.5 IU/h (Group 2.5), 5 IU/h (Group 5) or 10 IU/h (Group 10) following 3 IU slow bolus. The primary outcome measure was estimated intraoperative blood loss; secondary outcome measures included uterine tone adequacy, requirements for additional uterotonics, and any side effects. Minor postpartum hemorrhage (PPH) was defined as blood loss > 500 ml and major/severe hemorrhage as blood loss > 1000 ml.

RESULTS

Group 10 had minimum blood loss (311.1 ± 44.9 ml) and uterotonic requirements compared to other groups (p < 0.001). Group 2.5 had maximum blood loss (549.4 ± 74.3 ml) and uterotonic requirements; Group 5 had intermediate values (402.0 ± 49.5 ml). Twenty-six patients in group 2.5 had minor PPH against only one in group 5 and none in group 10 (p < 0.001). No patient in either group had major PPH. The incidence of hypotension was higher in group 10 than in group 2.5 (p = 0.004). Nausea and vomiting were also more frequent in group 10 than in the other two groups.

CONCLUSION

Oxytocin infusions at 5 IU/h and 10 IU/h are more effective in reducing blood loss and preventing PPH than 2.5 IU/h. The dose of 10 IU/h, although the most efficacious, is associated with a high incidence of side effects. Hence, further studies are needed to find out the optimal maintenance infusion rate of oxytocin during cesarean section in laboring patients who have received oxytocin earlier.

Obstetrical Hemorrhage

Obstetric hemorrhage is a leading cause of morbidity and mortality. Prevention includes identifying patients with risk factors and actively managing the third stage of labor. The anesthesiologist should be ready to manage hemorrhage with general strategies as well as strategies tailored to the specific cause of hemorrhage. Both neuraxial anesthesia and general anesthesia are appropriate in different situations. Treatments proven to be effective include increasing the oxytocin infusion, administering tranexamic acid early, guiding transfusion with point-of-care tests, and using cell salvage. Utilization of protocols and checklists within systems that encourage effective communication between teams should be implemented.

Prophylactic Phenylephrine Increases the Dose Requirement of Oxytocin to Treat Uterine Atony During Cesarean Delivery: A Double-Blinded, Single-Center, Randomized and Placebo-Controlled Trial

Purpose: Studies involving mouse models and human uterine smooth muscle cells have shown that phenylephrine inhibits uterine contractions in non-pregnant mice and human in vitro cell via cyclic adenosine monophosphate (cAMP) signaling. However, there has been no limited exploration to date of the effect of phenylephrine on uterine contractions in clinical practice. This study aimed to compare the dose requirement of oxytocin with or without the infusion of prophylactic phenylephrine to prevent post spinal hypotension during cesarean delivery under combined spinal and epidural anesthesia.

Methods: This was a double-blinded, single-center, randomized, control study. One hundred and sixty pregnant patients provided informed consent and were randomly allocated to the phenylephrine (phenylephrine infusion) and control (saline infusion) groups. Patients randomized to the phenylephrine group received an intravenous prophylactic phenylephrine infusion at a fixed rate of 0.5 μg/kg/min. The control group received a saline placebo at the same rate and used the same apparatus for delivery. After neonatal delivery and clamping of the umbilical cord, patients received a standard institutional oxytocin protocol. The primary outcome measure was the total dose of oxytocin administered during CD. Secondary outcomes including the proportion (%) of patients requiring a secondary uterotonic agent and estimated blood loss (EBL) in the first 24 h after surgery.

Results: The median oxytocin dose administered was significantly higher in the phenylephrine group than in the control group [6.9 ± 2.5 international standardized units (IU) vs. 5.4 ± 2.4 IU, p = 0.0004]. The number of patients that required a secondary uterotonic agent was significantly higher in the phenylephrine group than in the control group (24.2% vs. 9.1%; p = 0.034). The EBL in the first 24-h postoperatively was similar between the two groups (467 ± 47 ml vs. 392 ± 38 ml; p = 0.22).

Conclusions: Prophylactic infusion of phenylephrine used to prevent post-spinal hypotension during CD was associated with a higher dose of oxytocin. This has important clinical implications, as the suboptimal use of oxytocin is associated with an increased risk of postpartum hemorrhage and increased maternal morbidity and mortality. Further studies are now needed to confirm these findings.

The Intraoperative Median Effective Dose of Oxytocin for Preventing Uterine Atony in Parturients with a Prior History of Caesarean Delivery

BACKGROUND AND OBJECTIVE

While oxytocin is commonly used for the prevention of uterine atony, its pharmacology may be affected by a prior history of caesarean delivery. The objective of this study was to determine the 50% effective dose (ED₅₀) of bolus oxytocin after caesarean delivery in parturients with and without prior caesarean delivery.

METHODS

This was a parallel-group, double-blind, dose-response study using Dixon's up-and-down sequential allocation method to estimate the ED₅₀ of bolus-administered oxytocin in parturients having caesarean delivery under combined spinal-epidural anaesthesia (CSE). Twenty-seven parturients with a history of prior caesarean delivery (With-PCD group) and 26 parturients with no such history (Without-PCD group) were enrolled. Oxytocin was administered as an intravenous bolus at a starting dose of 0.5 units, which was then increased or decreased by 0.25 units at a time. Uterine tone was assessed by the obstetrician as either 'adequate' or 'inadequate' 3 min after delivery of the fetus. Adverse effects, administration of additional uterotonic agents, and estimated blood loss were recorded.

RESULTS

The ED₅₀ of oxytocin was greater in the With-PCD group than in the Without-PCD group (0.95 units [95% CI 0.82-1.08] vs. 0.55 units [95% CI 0.38-0.73], P < 0.001). The overall incidence of adverse effects was higher in the With-PCD group than in the Without-PCD group (33.3% vs. 7.7%, P = 0.02).

CONCLUSION

The initial bolus dose of oxytocin needed to prevent uterine atony was higher in parturients with prior caesarean delivery than in parturients without prior caesarean delivery. Uterine scarring may contribute to the increased oxytocin requirements of the former group.

TRIAL REGISTRATION NUMBER

ChiCTR1900023474; investigator: Wei CN; date of registration: 30 May 2019.

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.

Effective Dose of Prophylactic Oxytocin Infusion During Cesarean Delivery in 90% Population of Nonlaboring Patients With Preeclampsia Receiving Magnesium Sulfate Therapy and Normotensives: An Up-Down Sequential Allocation Dose-Response Study

BACKGROUND

Oxytocin administration during cesarean delivery is the first-line therapy for the prevention of uterine atony. Patients with preeclampsia may receive magnesium sulfate, a drug with known tocolytic effects, for seizure prophylaxis. However, no study has evaluated the minimum effective dose of oxytocin during cesarean delivery in women with preeclampsia.

METHODS

This study compared the effective dose in 90% population (ED90) of oxytocin infusion for achieving satisfactory uterine tone during cesarean delivery in nonlaboring patients with preeclampsia who were receiving magnesium sulfate treatment with a control group of normotensives who were not receiving magnesium sulfate. This prospective dual-arm dose-finding study was based on a 9:1 biased sequential allocation design. Oxytocin infusion was initiated at 13 IU/h, on clamping of the umbilical cord, in the first patient of each group. Uterine tone was graded as satisfactory or unsatisfactory by the obstetrician at 4 minutes after initiation of oxytocin infusion. The dose of oxytocin infusion for subsequent patients was decided according to the response exhibited by the previous patient in the group; it was increased by 2 IU/h after unsatisfactory response or decreased by 2 IU/h or maintained at the same level after satisfactory response, in a ratio of 1:9. Oxytocin-associated side effects were also evaluated. Dose-response data for the groups were evaluated using a log-logistic function and ED90 estimates were derived from fitted equations using the delta method.

RESULTS

The ED90 of oxytocin was significantly greater for the preeclampsia group (n = 27) than for the normotensive group (n = 40) (24.9 IU/h [95% confidence interval {CI}, 22.4-27.5] and 13.9 IU/h [95% CI, 12.4-15.5], respectively); the difference in dose requirement was 10.9 IU/h (95% CI, 7.9-14.0; P < .001). The number of patients with oxytocin-related hypotension, defined as a decrease in systolic blood pressure >20% from baseline or to <90 mm Hg, was significantly greater in the preeclampsia group (92.6% vs 62.5%; P = .030), while other side effects such as ST-T depression, nausea/vomiting, headache, and flushing, were not significantly different. There was no significant difference in the need for additional uterotonic or uterine massage, estimated blood loss, and need for re-exploration for uncontrolled bleeding.

CONCLUSIONS

Patients with preeclampsia receiving preoperative magnesium therapy need a greater intraoperative dose of oxytocin to achieve satisfactory contraction of the uterus after fetal delivery, as compared to normotensives.

Obstetric Anesthesia and Heart Disease: Practical Clinical Considerations

Maternal morbidity and mortality as a result of cardiac disease is increasing in the United States. Safe management of pregnancy in women with heart disease requires appropriate anesthetic, cardiac, and obstetric care. The anesthesiologist should risk stratify pregnant patients based upon cardiac disease etiology and severity in order to determine the appropriate type of hospital and location within the hospital for delivery and anesthetic management. Increased intrapartum hemodynamic monitoring may be necessary and neuraxial analgesia and anesthesia is typically appropriate. The anesthesiologist should anticipate obstetric and cardiac emergencies such as emergency cesarean delivery, postpartum hemorrhage, and peripartum arrhythmias. This clinical review answers practical questions for the obstetric anesthesiologist and the nonsubspecialist anesthesiologist who regularly practices obstetric anesthesiology.

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.

Society for Obstetric Anesthesia and Perinatology: Consensus Statement and Recommendations for Enhanced Recovery After Cesarean

The purpose of this article is to provide a summary of the Enhanced Recovery After Cesarean delivery (ERAC) protocol written by a Society for Obstetric Anesthesia and Perinatology (SOAP) committee and approved by the SOAP Board of Directors in May 2019. The goal of the consensus statement is to provide both practical and where available, evidence-based recommendations regarding ERAC. These recommendations focus on optimizing maternal recovery, maternal-infant bonding, and perioperative outcomes after cesarean delivery. They also incorporate management strategies for this patient cohort, including recommendations from existing guidelines issued by professional organizations such as the American College of Obstetricians and Gynecologists and the American Society of Anesthesiologists. This consensus statement focuses on anesthesia-related and perioperative components of an enhanced recovery pathway for cesarean delivery and provides the level of evidence for each recommendation.

Efficacy of different infusion rates of oxytocin for maintaining uterine tone during elective caesarean section: A randomised double blind trial

Most research in this field has focused on finding oxytocin doses for initiating uterine contractions. Only limited data are available regarding the optimal rate of oxytocin infusion to maintain adequate uterine tone. This randomised, double blind study included 120 healthy term pregnant patients with uncomplicated, singleton pregnancy undergoing elective caesarean section under spinal anaesthesia. Following an initial 1 IU bolus, the patients received oxytocin infusion at 1.25 IU/hour (group 1.25), 2.5 IU/hour (group 2.5) or 5.0 IU/hour (group 5) for four hours. Uterine tone was assessed as adequate or inadequate at various intervals. If found inadequate, additional uterotonics were administered. Estimated blood loss was mean (standard deviation) 499 (172) ml, 454 (117) ml and 402 (151) ml in groups 1.25, 2.5 and 5, respectively (P value groups 1.25 versus 5 = 0.012). Oxytocin infusion at 5 IU/hour resulted in a significantly lower incidence of minor postpartum haemorrhage, defined as blood loss greater than 500 ml, than 1.25 IU/hour (P = 0.009). No patient had major/severe haemorrhage (>1000 ml blood loss). No significant difference was seen in haemoglobin levels (P = 0.677) and uterine tone. Fifteen, six and nine patients, respectively, required additional oxytocin (P = 0.151). The incidence of tachycardia (P = 0.726), hypotension (P = 0.321) and nausea/vomiting (P = 0.161) was comparable. To conclude, 5 IU/hour was more effective than 1.25 IU/hour in reducing total blood loss and the incidence of minor postpartum haemorrhage. Thus 5 IU/hour appears to be an optimal oxytocin infusion rate following 1 IU slow intravenous oxytocin injection for the maintenance of adequate uterine contraction in patients undergoing elective caesarean section under spinal anaesthesia.

European minimum standards for obstetric analgesia and anaesthesia departments: An experts' consensus

: An important variability of anaesthetic standards of care was discovered in the obstetric departments of many European Union countries. After discussing this issue in various meetings of the European Society of Anaesthesiology (ESA) board and its obstetric subcommittee, European Board of Anaesthesiology of the European Union of Medical Specialists (EBA-UEMS) executive members, ESA obstetric subcommittee members and European experts in obstetric anaesthesiology have participated in the elaboration of this document. This experts' opinion is focused mainly on obstetric patients and safety concerns in terms of minimum standards of practice. An initial bibliographical search was performed in medical databases and general literature, searching for obstetric anaesthesiology standards to select the most important safety issues. After the initial presentation of the project during EBA-UEMS and ESA obstetric subcommittee meetings, participants were asked to review the document; several rounds of revisions were performed by the experts, to reach a common opinion concerning the topics considered central to patient safety in the obstetric setting. After three rounds of revision, a consensus was reached and is presented in this document, which includes the list of topics considered relevant by the involved areas, and the respective recommendations. These recommendations covered some EBA-UEMS strategic key areas, in addition to several clinical aspects of common obstetric practice.

The Median Effective Dose of Oxytocin Needed to Prevent Uterine Atony During Cesarean Delivery in Elderly Parturients

Purpose

Oxytocin is the first-line agent to prevent and treat uterine atony during cesarean delivery (CD). We compared the effective dose in 50% of the parturients (ED₅₀) of a prophylactic oxytocin bolus during CD in young (<35 years) and old parturients (≥35 years) using Dixon’s up-and-down method.

Patients and Methods

Twenty-eight young parturients (young group) and 25 old parturients (old group) undergoing CD under combined spinal-epidural anesthesia were enrolled. The initial oxytocin bolus was 0.5 IU, with increments or decrements of 0.25 IU. Maternal adverse effects, requirement for additional uterotonic agents, and estimated blood loss were recorded.

Results

The ED₅₀ for oxytocin in the old group was higher than that in the young group (1.41 IU; 95% confidence interval, 0.63–2.19) vs 0.66 IU (0.04–1.29), P < 0.001). The total oxytocin dose in the old group was higher than in the young group (5.9 ± 2.9 vs 4.1 ± 2.1 IU, P = 0.01). The estimated blood loss in the older group and young group was 401.2 ± 204.5 mL and 289.3 ± 104.6 mL, respectively (P =0.01). The overall prevalence of adverse effects was higher in the old group than in the young group (68.0% vs 21.4%, P < 0.001).

Conclusion

The initial bolus and total requirement of oxytocin for preventing uterine atony were higher in old parturients than in young parturients during CD. Advanced maternal age may necessitate higher doses of oxytocin.

Obstetric Hemorrhage

Peripartum hemorrhage is a leading cause of maternal morbidity and mortality. Anesthesiologists must be familiar with conditions associated with hemorrhage that are unique to labor and delivery and not seen elsewhere in their practice. Regardless of etiology, early recognition and timely treatment of obstetric hemorrhage is necessary to prevent significant blood loss. Massive transfusion protocols are crucial to successful resuscitation, and providers should also consider use of cell salvage, uterine artery embolization, and anti-fibrinolytics. Because more than half the deaths due to hemorrhage are preventable, multidisciplinary care bundles should be used on every labor and delivery unit.

The effect of an oxytocin washout period on blood loss at cesarean delivery

Objectives Prolonged oxytocin exposure may result in increased blood loss during delivery. Our objective was to determine whether an oxytocin rest period before cesarean delivery had an impact on blood loss. Methods We performed a retrospective cohort study of women who underwent primary cesarean delivery after oxytocin augmentation. The primary outcome was change between pre- and postoperative hematocrit (Hct) in women with less than 60-min oxytocin rest period (<60 min) and greater than 60-min rest period (>60 min). Results There was no difference in demographic characteristics (age, BMI, or gestational age at delivery) between the two groups. Women in the >60 min group had a higher cumulative dose and longer duration of oxytocin administration. There was no significant difference in change in Hct between the two groups when controlling for these factors. Conclusions We did not find a significant correlation between the duration of the oxytocin rest period and blood loss. Oxytocin washout periods of greater than 60 min may not result in decreased blood loss at cesarean delivery, and thus, women may not benefit from such oxytocin washout periods.

Predicting Postpartum Hemorrhage After Low-Risk Vaginal Birth by Labor Characteristics and Oxytocin Administration

OBJECTIVE

To determine the odds of postpartum hemorrhage (PPH) in low-risk women who gave birth vaginally and were exposed to different durations and dosages of oxytocin across a range of labor durations during spontaneous or induced labor.

DESIGN

A retrospective cross-sectional analysis of data from the Consortium for Safe Labor.

SETTING

Data were gathered from 12 clinical institutions across the United States from 2002 to 2008.

PARTICIPANTS

After exclusion of high-risk conditions associated with PPH, we examined data from 27,072 women who gave birth vaginally.

METHODS

PPH was defined as estimated blood loss of greater than 500 ml at the time of birth and/or a diagnostic code for PPH before hospital discharge. We included covariates were if they were associated with oxytocin use and PPH and did not mediate oxytocin use. We used regression models to determine the likelihood of PPH overall and within the induced and spontaneous labor groups separately. We used subgroup analyses within specific durations of labor to clarify the findings.

RESULTS

The overall rate of PPH was 3.9%. Women with induced labor experienced PPH more frequently than women who labored spontaneously. Labor augmentation was associated with greater adjusted odds for PPH when oxytocin was infused for more than 4 hours. Longer duration of spontaneous labor and the second stage of labor did not change this association. Oxytocin use during labor induction increased the odds for PPH when administered for more than 7 hours. The odds further increased when induction lasted longer than 12 hours and/or the second stage of labor was longer than 3 hours.

CONCLUSION

Strategies for judicious oxytocin administration may help mitigate PPH in low-risk women having vaginal birth.

The ED50 and ED95 of oxytocin infusion rate for maintaining uterine tone during elective caesarean delivery: a dose-finding study

Background

The 90% effective dose (ED₉₀) of oxytocin infusion has been previously estimated to be 16.2 IU h^− 1. However, bolus administration of oxytocin prior to the infusion may decrease the infusion dose required. The aim of this study was to estimate the ED₉₅ for oxytocin infusion after a bolus at elective caesarean delivery (CD) in nonlaboring parturients.

Methods

We performed a randomized, triple blinded study in 150 healthy termparturients scheduled for elective CD under epidural anaesthesia. After delivery of the infant and i.v. administration of 1 IU oxytocin as a bolus, Participants were randomized to receive oxytocin infusion at a rate of 0, 1, 2, 3, 5, or 8 IU h^− 1, to be given for a total of 1 h. Uterine tone assessed by the blinded obstetrician as either adequate or inadequate. Secondary outcomes included estimated blood loss (EBL), requirement for supplemental uterotonic agents, and development of side effects.

Results

The 95% effective dose (ED₉₅) of oxytocin infusion was estimated to be 7.72 IU h^− 1 (95% confidence interval 5.80–12.67 IU h^− 1). With increasing oxytocin infusion rate, the proportion of parturients who needed rescue oxytocin bolus or secondary uterotonic agents decreased. No significant among-group differences in the EBL and oxytocin-related side effects were observed.

Conclusions

In parturients who receive a 1 IU bolus of oxytocin during elective cesarean delivery, an infusion rate of oxytocin at 7.72 IU h^− 1 will produce adequate uterine tone in 95% of parturients. These results suggest that the total dose of oxytocin administered in the postpartum period can be decreased when administered as an infusion after oxytocin bolus.

Using misoprostol to treat postpartum hemorrhage in home deliveries attended by traditional birth attendants

OBJECTIVE

To explore the clinical and programmatic feasibility of using 800 μg of sublingual misoprostol to prevent and treat postpartum hemorrhage (PPH) during home delivery.

METHODS

The present double-blind randomized controlled trial included women who underwent home deliveries in Chitral district, Khyber Pakhtunkhwa province, Pakistan, after presenting at healthcare facilities during the third trimester of pregnancy between May 28, 2012, and November 27, 2014. Participants were randomized in a 1:1 ratio to receive either 800 μg of misoprostol or placebo sublingually if PPH was diagnosed, having previously received a prophylactic oral dose of 600 μg misoprostol. The primary outcome, hemoglobin decrease of 20 g/L or greater from pre- to post-delivery assessment, was compared on a modified intention-to-treat basis.

RESULTS

There were 49 patients allocated to receive misoprostol and 38 allocated to receive placebo; the incidence of a 20 g/L decrease in hemoglobin was similar between the groups (20/43 [47%] vs 19/33 [58%], respectively; P=0.335).

CONCLUSION

There was no significant difference in clinical outcomes between the two trial arms. ClinicalTrials.gov:NCT01485562.

A Review of the Impact of Obstetric Anesthesia on Maternal and Neonatal Outcomes

Obstetric anesthesia has evolved over the course of its history to encompass comprehensive aspects of maternal care, ranging from cesarean delivery anesthesia and labor analgesia to maternal resuscitation and patient safety. Anesthesiologists are concerned with maternal and neonatal outcomes, and with preventing and managing complications that may present during childbirth. The current review will focus on recent advances in obstetric anesthesia, including labor anesthesia and analgesia, cesarean delivery anesthesia and analgesia, the effects of maternal anesthesia on breastfeeding and fever, and maternal safety. The impact of these advances on maternal and neonatal outcomes is discussed. Past and future progress in this field will continue to have significant implications on the health of women and children.

Patients Undergoing Cesarean Delivery After Exposure to Oxytocin During Labor Require Higher Postpartum Oxytocin Doses

BACKGROUND

Experts recommend postpartum oxytocin to prevent uterine atony and hemorrhage, but oxytocin may be associated with dose-dependent adverse effects, and the correct dose of postpartum oxytocin has yet to be determined. The effective dose in 90% of patients (ED90) of oxytocin after cesarean delivery may be higher in patients exposed to oxytocin during labor compared to patients unexposed. We therefore undertook this study to compare postpartum oxytocin requirements in patients exposed to oxytocin prior to cesarean delivery versus those not exposed, when all were treated according to a specific institutional protocol.

METHODS

In this retrospective chart review, we reviewed medical records of patients who underwent cesarean delivery under neuraxial anesthesia and noted demographic data, relevant comorbidities, and oxytocin exposure, infusion rate, and duration prior to delivery. Patients exposed to oxytocin before cesarean (OXY+ group) were compared to those not exposed (OXY- group). The primary outcome variable was highest infusion rate of postpartum oxytocin required per institutional protocol. Secondary outcomes included estimated blood loss, proportion of patients with postpartum hemorrhage, and proportions who received other uterotonic medications or red blood cell transfusion.

RESULTS

OXY+ patients were more likely to be nulliparous and had higher estimated gestational age and neonatal weight than OXY- patients. They also had higher incidence of chorioamnionitis and lower incidence of multiple gestation. OXY+ patients required a high postpartum oxytocin infusion rate more often than OXY- patients (adjusted odds ratio 1.94 [95% confidence interval, 1.19-3.15; P = .008]). They also received other uterotonic agents more commonly. Estimated blood loss, hemorrhage rates, and transfusion rates did not differ between groups.

CONCLUSIONS

Reported increases in the ED90 of postpartum oxytocin after oxytocin exposure during labor appear to be clinically significant. We have therefore altered our institutional protocol so that women preexposed to oxytocin routinely receive higher initial postpartum oxytocin infusion rates.

Paucity of evidence for the effectiveness of prophylactic low-dose oxytocin protocols (<5 IU) compared with 5 IU in women undergoing elective caesarean section: A systematic review of randomised controlled trials

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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.

Lack of controlled studies investigating the risk of postpartum haemorrhage in cesarean delivery after prior use of oxytocin: a scoping review

BACKGROUND

Postpartum haemorrhage (PPH) is a major cause of maternal mortality and morbidity worldwide. Experimental and clinical studies indicate that prolonged oxytocin exposure in the first or second stage of labour may be associated with impaired uterine contractility and an increased risk of atonic PPH. Therefore, particularly labouring women requiring cesarean delivery constitute a subset of patients that may exhibit an unpredictable response to oxytocin. We mapped the evidence for comparative studies investigating the hypothesis whether the risk for PPH is increased in women requiring cesarean section after induction or augmentation of labour.

METHODS

We performed a systematic literature search for clinical trials in Medline, Embase, Web of Science, and the Cochrane Library (May 2016). Additionally we searched for ongoing or unpublished trials in clinicaltrials.gov and the WHO registry platform. We identified a total of 36 controlled trials investigating the exogenous use of oxytocin in cesarean section. Data were extracted for study key characteristics and the current literature literature was described narratively.

RESULTS

Our evidence map shows that the majority of studies investigating the outcome PPH focused on prophylactic oxytocin use compared to other uterotonic agents in the third stage of labour. Only 2 dose-response studies investigated the required oxytocin dose to prevent uterine atony after cesarean delivery for labour arrest. These studies support the hypotheses that labouring women exposed to exogenous oxytocin require a higher oxytocin dose after delivery than non-labouring women to prevent uterine atony after cesarean section. However, the study findings are flawed by limitations of the study design as well as the outcome selection. No clinical trial was identified that directly compared exogenous oxytocin versus no oxytocin application before intrapartum cesarean delivery.

CONCLUSION

Despite some evidence from dose-response studies that the use of oxytocin may increase the risk for PPH in intrapartum cesarean delivery, current research has not investigated the prepartal application of oxytocin in well controlled clinical trials. It was striking that most studies on exogenous oxytocin are focused on PPH prophylaxis in the third stage of labour without differing between the indications of cesarean section and hence the prepartal oxytocin status.

Peripartum Haemorrhage: Haemostatic Aspects of the New German PPH Guideline

Summary Peripartum haemorrhage remains one of the main causes of maternal mortality world-wide. The German, Austrian and Swiss Societies of Gynaecology and Obstetrics have updated the current guidelines for the treatment of peripartum haemorrhage together with the German Society of Anaesthesiology and Intensive Care Medicine and the Society of Thrombosis and Haemostasis Research. The recommendations have been the result of a thorough review of the available scientific literature and a consensus process involving all members of the guideline group. A key element of the anaesthesiological and haemostatic management is the development of a multidisciplinary standard operating procedure combining surgical as well as medical and haemostatic treatments depending on the severity of bleeding. The guideline underscores the value of clinical and laboratory diagnostics of peripartum haemorrhage as early as possible, even pre-emptively. This allows for an early identification of causes of bleeding and a specific treatment. The guideline comprises evidence-based recommendations for the use of uterotonics, tranexamic acid and blood products such as factor concentrates, fresh frozen plasma, platelet concentrates, packed red blood cells, recombinant activated factor VII and desmopressin. In addition, recommendations for blood conservation strategies involving the use of cell salvage, permissive hypotension and transfusion triggers are given.

Effect of a High-Rate Versus a Low-Rate Oxytocin Infusion for Maintaining Uterine Contractility During Elective Cesarean Delivery: A Prospective Randomized Clinical Trial

BACKGROUND

Oxytocin is routinely used as prophylaxis against uterine atony. During elective cesarean delivery (CD), an oxytocin bolus is used to initiate adequate uterine tone, followed by an oxytocin infusion to maintain uterine contractility. However, it is unclear whether oxytocin maintenance infusion rate influences total estimated blood loss (EBL).

METHODS

We performed a prospective, randomized, double-blind trial in 51 women undergoing elective CD. Women were randomly assigned to receive an oxytocin maintenance infusion of 2.5 or 15 U/h. All women received an oxytocin 1 U bolus to initiate adequate uterine tone. The primary outcome was EBL. EBL values between groups were compared using a Mann-Whitney U test; P < .05 as statistically significant. The median EBL difference with 95% confidence intervals was also calculated. Secondary outcomes included adequacy of uterine tone, use of additional uterotonics, and oxytocin-related side effects, including hypotension.

RESULTS

Of 51 women, 24 received a low-rate infusion and 27 received a high-rate infusion. Median (interquartile range) EBL values in the low-rate and high-rate groups were 634 (340-886) mL versus 512 (405-740) mL, respectively (P = .7). The median difference in EBL between groups was 22 mL; 95% confidence interval = -158 to 236 mL. The rate of postpartum hemorrhage did not differ between groups (low-rate group: 4/24 [16.7%] versus high-rate group: 4/26 [15.4%]). There were no between-group differences over time (first 20 minutes after commencing infusion) in the incidence of adequate uterine tone (P = .72) or hypotension (P = .32).

CONCLUSIONS

Among women undergoing elective CD receiving an oxytocin maintenance infusion, EBL and uterine tone did not differ between women receiving 2.5 U/h oxytocin and those receiving 15 U/h oxytocin. Our findings suggest that efficacy can be obtained with a low oxytocin maintenance infusion rate; however, dose-finding studies are needed to determine the infusion rate that optimizes drug efficacy while minimizing side effects.

Regional cerebral oxygen saturation guided cerebral protection in a parturient with Takayasu's arteritis undergoing cesarean section: a case report

The objective of this case report is to present the successful use of regional cerebral oxygen saturation (rScO2) monitoring guided cerebral protection for cesarean delivery in a parturient with Takayasu's arteritis at 38weeks' gestation. The parturient presented with impaired cerebral and renal perfusion. Titrated epidural anesthesia was performed. During the procedure, we used rScO2 guided cerebral protection strategies, which helped to optimize cerebral oxygen delivery and prevent cerebral complications.