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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., (© 2022. The Author(s) under exclusive licence to Japanese Society of Anesthesiologists.)

Background: The two most commonly used uterotonic drugs in caesarean section are oxytocin and carbetocin, a synthetic oxytocin analogue. Carbetocin has a longer half-life when compared to oxytocin, resulting in a reduced use of additional uterotonics. Oxytocin is known to cause fewer cardiovascular side effects when administered as a short-infusion compared to as an intravenous bolus. Based on these findings, we aim at comparing carbetocin 100 mcg given as a slow intravenous bolus with carbetocin 100 mcg applied as a short-infusion in 100 ml 0.9 % sodium chloride in women undergoing a planned or unplanned caesarean delivery. We hypothesise uterine contraction not to be inferior to a bolus application (primary efficacy endpoint) and greater haemodynamic stability to be achieved after a short-infusion than after a bolus administration, as measured by heart rate and mean arterial blood pressure (primary safety endpoint)., Methods/design: This is a prospective, double-blind, randomised controlled, investigator-initiated, non-inferiority trial taking place at the University Hospital Basel, Switzerland. Uterine tone is quantified by manual palpation by the obstetrician using a linear analogue scale from 0 to 100 at 2, 3, 5 and 10 minutes after cord clamping. We will evaluate whether the lower limit of the confidence interval for the difference of the maximal uterine tone within the first 5 minutes after cord clamping between both groups does not include the pre-specified non-inferiority limit of -10. Both haemodynamic secondary endpoints will be analysed using a linear regression model, adjusting for the baseline value and the dosage of vasoactive drug given between cord clamping and 1 minute thereafter, in order to investigate superiority of a short-infusion as compared to a bolus application. We will follow the extension of CONSORT guidelines for reporting the results of non-inferiority trials., Discussion: Haemodynamic stability and adequate uterine tone are important outcomes in caesarean sections. The results of this trial may be used to optimise these factors and thereby increase patient safety due to a reduction in cardiovascular side effects., Trial Registration: Clinicaltrials.gov NCT02221531 on 19 August 2014 and www.kofam.ch SNCTP000001197 on 15 November 2014.

Background: Oxytocin administration to prevent uterine atony following cesarean delivery is associated with adverse effects including hypotension, tachycardia, and nausea. Calcium chloride increases mean arterial pressure, systemic vascular resistance, and uterine smooth muscle contractility. This study evaluated whether the co-administration of calcium chloride with oxytocin following cesarean delivery could alter maternal hemodynamics. Secondary outcomes included uterine tone and blood loss., Methods: Sixty healthy parturients with singleton, term, vertex pregnancies undergoing elective cesarean delivery under spinal anesthesia were randomized to one of three study solutions given intravenously immediately after umbilical cord clamping: (1) placebo, oxytocin 5U alone; (2) CA-200, oxytocin 5U+calcium chloride 200mg; or (3) CA-400, oxytocin 5U+calcium chloride 400mg. Blood pressure, heart rate, uterine tone, vasopressor or alternate uterotonic use and the incidence of nausea or vomiting were recorded. Baseline and intraoperative plasma concentration of ionized calcium and hematocrit were measured., Results: Plasma concentration of ionized calcium was elevated in both study groups compared with placebo (P=0.001). Blood pressure decreased and heart rate increased in all groups (P <0.0001), with no differences between groups. No differences were observed between groups in uterine tone, vasopressor use, hematocrit change, estimated blood loss, incision-to-delivery interval, delivery-to-skin closure interval, total intravenous fluid administered or incidence of nausea., Conclusions: The decrease in blood pressure associated with oxytocin administration following cesarean delivery was not attenuated with co-administration of calcium chloride at the doses evaluated. Vasopressor use, uterine tone, and blood loss were also unaffected., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Abstract 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 ).

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). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Oxytocin (OT) is routinely administered during caesarean delivery to prevent and treat postpartum haemorrhage (PPH). The common adverse effects of intravenous OT are tachycardia, hypotension, chest pain, Electrocardiogram (ECG) changes, nausea and vomiting. We aimed to compare the uterine contractility, haemodynamic changes, need for other uterotonics and adverse effects by comparing the intravenous bolus dose versus infusion dose of OT while retaining its benefits. Methods: Sixty patients undergoing elective caesarean delivery under spinal anaesthesia were randomised to receive OT 3 IU as a bolus (repeat 3 IU at an interval of 3 min) in group B (Bolus) or as an infusion 1 IU per minute in group I (infusion). The uterine tone was assessed by a blinded obstetrician as either adequate or inadequate. The intraoperative heart rate, blood pressure, blood loss and any other adverse events were recorded. Results: The adequacy of uterine tone was more sustained and the requirement of other uterotonics was less in group I. The heart rate increased to 20–25 beats/min at 3–5 min in group B and 8–10 beats/min at 2–4 mins and reached the baseline at 8–9 min in group B as well as in group I. Also, a significant fall in the mean blood pressure was observed at 3–5 min in group B. The ECG changes (ST-T changes) were more common in group B compared to group I. There was no significant difference in the estimated blood loss between the two groups. Conclusion: The infusion dose of OT provides more haemodynamic stability, better uterine tone and fewer adverse effects compared to the bolus dose.

Background: Oxytocin (OT) is routinely administered during caesarean delivery to prevent and treat postpartum haemorrhage (PPH). The common adverse effects of intravenous OT are tachycardia, hypotension, chest pain, Electrocardiogram (ECG) changes, nausea and vomiting. We aimed to compare the uterine contractility, haemodynamic changes, need for other uterotonics and adverse effects by comparing the intravenous bolus dose versus infusion dose of OT while retaining its benefits. Methods: Sixty patients undergoing elective caesarean delivery under spinal anaesthesia were randomised to receive OT 3 IU as a bolus (repeat 3 IU at an interval of 3 min) in group B (Bolus) or as an infusion 1 IU per minute in group I (infusion). The uterine tone was assessed by a blinded obstetrician as either adequate or inadequate. The intraoperative heart rate, blood pressure, blood loss and any other adverse events were recorded. Results: The adequacy of uterine tone was more sustained and the requirement of other uterotonics was less in group I. The heart rate increased to 20–25 beats/min at 3–5 min in group B and 8–10 beats/min at 2–4 mins and reached the baseline at 8–9 min in group B as well as in group I. Also, a significant fall in the mean blood pressure was observed at 3–5 min in group B. The ECG changes (ST-T changes) were more common in group B compared to group I. There was no significant difference in the estimated blood loss between the two groups. Conclusion: The infusion dose of OT provides more haemodynamic stability, better uterine tone and fewer adverse effects compared to the bolus dose. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

Purpose: Oxytocin is the preferred choice for prophylaxis and treatment of postpartum hemorrhage. Intravenous infusion has been a widely accepted route for Oxytocin administration. However, intravenous bolus route is not a readily preferred route due to apprehensions regarding hypotension that it may cause. This trial compares low dose 3 IU intravenous (IV) bolus Oxytocin along with 7 IU Oxytocin in intravenous infusion to 10IU Oxytocin intravenous infusion during cesarean section. Patients and Methods: A total of 250 term pregnant women were randomized to either 3 IU intravenous bolus with 7 IU intravenous infusion of Oxytocin or 10IU of intravenous Oxytocin infusion. The difference in pre- and post-operative hemoglobin levels, tone of the uterus, hemodynamic changes, adverse effects of the drug, need for additional uterotonics and need for blood transfusions were assessed. Results: There was 6.7% less blood loss in the 3 IU IV bolus Oxytocin with 7 IU Oxytocin infusion group in comparison to the Oxytocin infusion group. The tone of the uterus was firmer in IV bolus Oxytocin with Oxytocin infusion group at 5 minutes (p< 0.001) than the Oxytocin infusion group. There was no significant difference in the hemodynamic changes, adverse effects or need for blood transfusions. Conclusion: Intravenous bolus of 3 IU Oxytocin along with 7 IU infusion of Oxytocin is as safe and more effective than intravenous infusion of 10 IU of Oxytocin during cesarean section in the prevention of postpartum hemorrhage. [ABSTRACT FROM AUTHOR]

Background: Oxytocin is routinely administered during cesarean delivery for uterine contraction. Adverse effects are known to occur after intravenous oxytocin administration, notably tachycardia, hypotension, and electrokardiogram (EKG) changes, which can be deleterious in high-risk patients. Aims and Objectives: To compare the hemodynamic changes and uterotonic effect of equivalent dose of oxytocin administered as an intravenous bolus versus intravenous infusion. Study Design: Randomized, double-blind, active controlled trial. Materials and Methods: Eighty parturients undergoing elective cesarean delivery, under spinal anesthesia, were randomly allocated to receive 3 IU of oxytocin either as a bolus intravenous injection over 15 seconds (group B, n = 40) or as an intravenous infusion over 5 minutes (group I, n = 40). Uterine tone was assessed as adequate or inadequate by an obstetrician. Intraoperative heart rate, non-invasive blood pressure, and EKG changes were recorded. These data were compared between the groups. Any other adverse events like chest pain, nausea, vomiting, and flushing were noted. Results: There was significant rise in heart rate and significant decrease in mean arterial pressure in bolus group compared to infusion group. Three patients in bolus group had EKG changes in the form of ST-T depression and 5 patients complained of chest pain. No such complications were found in infusion group. Conclusion: Bolus oxytocin (at a dose of 3 IU over 15 seconds) and infusion of oxytocin (at a dose of 3 IU over 5 minutes) have comparable uterotonic effect. However, the bolus regime shows significantly more adverse cardiovascular events.

Background: Oxytocin is routinely administered during cesarean delivery for uterine contraction. Adverse effects are known to occur after intravenous oxytocin administration, notably tachycardia, hypotension, and electrokardiogram (EKG) changes, which can be deleterious in high-risk patients. Aims and Objectives: To compare the hemodynamic changes and uterotonic effect of equivalent dose of oxytocin administered as an intravenous bolus versus intravenous infusion. Study Design: Randomized, double-blind, active controlled trial. Materials and Methods: Eighty parturients undergoing elective cesarean delivery, under spinal anesthesia, were randomly allocated to receive 3 IU of oxytocin either as a bolus intravenous injection over 15 seconds (group B, n = 40) or as an intravenous infusion over 5 minutes (group I, n = 40). Uterine tone was assessed as adequate or inadequate by an obstetrician. Intraoperative heart rate, non-invasive blood pressure, and EKG changes were recorded. These data were compared between the groups. Any other adverse events like chest pain, nausea, vomiting, and flushing were noted. Results: There was significant rise in heart rate and significant decrease in mean arterial pressure in bolus group compared to infusion group. Three patients in bolus group had EKG changes in the form of ST-T depression and 5 patients complained of chest pain. No such complications were found in infusion group. Conclusion: Bolus oxytocin (at a dose of 3 IU over 15 seconds) and infusion of oxytocin (at a dose of 3 IU over 5 minutes) have comparable uterotonic effect. However, the bolus regime shows significantly more adverse cardiovascular events. [ABSTRACT FROM AUTHOR]