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NCT Number: NCT05290129

Oxytocin Maintenance Infusion in Labouring Women Undergoing Cesarean Delivery: an Up-down Sequential Allocation Study

This study is designed to determine the minimal effective oxytocin maintenance infusion required in labouring women undergoing cesarean delivery to achieve the best effect. Oxytocin is a drug that is routinely used to help the uterus to contract and keep it contracted after delivery. Consequently, it will help to reduce blood loss after delivery. In order to determine the minimal effective dose, the investigators will conduct a dose-finding study. The first patient will receive a set oxytocin infusion. The next patient's infusion dose of oxytocin, will either increase or decrease, depending on how the previous patient responds in terms of uterine tone. If the response is satisfactory with the infusion dose used, the next patient will either receive the same infusion dose or it will be decreased depending on a probability of 1:9. If the response is not satisfactory, then the infusion dose will increase for the next patient. The dose for each patient will be determined based on the results of the uterine contraction of the previous patient.

The investigators hypothesize that the ED90 of the oxytocin infusion rate to maintain adequate uterine tone in labouring women with induced or augmented labour undergoing cesarean delivery, following an initial effective bolus dose, would be lower than 0.74 IU/min (44 IU/h), which was found as the ED90 in a previous study, without an initial bolus dose prior to the infusion.

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Key information

Conditions

Postpartum Hemorrhage Female Urogenital Diseases and Pregnancy Complications Hemorrhage Obstetric Labor Complications Pathologic Processes Pathological Conditions, Signs and Symptoms Pregnancy Complications Puerperal Disorders Urogenital Diseases Uterine Hemorrhage

Age range

18 year–50 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Mount Sinai Hospital

Toronto, Ontario, M5G1X5, Canada

Location status: Recruiting

About this study

This study will be conducted as a prospective, double blinded clinical trial (patient, anesthesiologist and obstetrician blinded to the oxytocin dose), in an up-down sequential allocation fashion. The objective of the study is to determine the minimum effective dose of oxytocin infusion required to produce appropriate uterine contraction during and after cesarean delivery under neuraxial anesthesia in laboring women. For the purpose of this study, the minimum effective dose is defined to be that at which adequate response occurs in 90% of patients, i.e. ED90.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • All patients with induced or augmented labour undergoing cesarean delivery under neuraxial anesthesia (at least 3 hours of prior exposure to oxytocin during labour)

Exclusion criteria

  • All patients who refuse to give written informed consent
  • All patients who declare allergy or hypersensitivity to oxytocin
  • A history of hypertension and/or severe cardiac disease(s)
  • All patients who have contraindications for neuraxial anesthesia
  • All patients who will be converted to general anesthesia intraoperatively
  • All patients with placenta previa and multiple gestation

Treatment and study plan

Oxytocin

Drug

Oxytocin will be prepared in a 1L bag of Ringer's lactate, to be infused at a rate of 125 ml/h.

Other names: Pitocin

Primary outcomes

  1. Uterine tone up to discharge from the post anesthetic care unit (PACU): questionnaire

    Time frame: 2 hours

    Uterine tone will be evaluated as satisfactory or unsatisfactory by the obstetrician throughout the surgery, starting at 5 minutes after the oxytocin infusion. It will also be measured at 10 minutes following the oxytocin infusion and every 10 minutes following that for the duration of the surgery. Unsatisfactory uterine tone at any time until discharge from the PACU will be considered a failure of the maintenance infusion.

Secondary outcomes

  1. Calculated blood loss

    Time frame: 24 hours

    Estimated blood loss will be calculated using the difference in hematocrit values prior to surgery and 24 hours post surgery, using the following formula:

    Calculated blood loss (mL) = EBV ((Pre-op Htc-Post-op Htc)/pre-op Htc) EBV (estimated blood volume) in ml: patient's weight in kg x 85.

  2. Need for blood transfusion

    Time frame: 24 hours

    Blood product administered.

  3. Episodes of bleeding postpartum

    Time frame: 24 hours

    Number of episodes of bleeding postpartum up to 24 hours post delivery.

  4. Intraoperative requirement for additional uterotonic medication

    Time frame: 1 hour

    A request made by the obstetrician performing the cesarean delivery for additional uterotonic medication, due to bleeding or poor uterine tone.

  5. Requirement for additional uterotonic medication in the PACU

    Time frame: 2 hours

    Any uterotonic medication administered while the patient is in PACU

  6. Requirement for additional uterotonic medication from discharge from the PACU until 24 hours postpartum.

    Time frame: 24 hours

    Any uterotonic medication administered after the patient is discharged from PACU until 24 hours postpartum.

  7. Hypotension: systolic blood pressure less than 80% of baseline

    Time frame: 2 hours

    Systolic blood pressure < 80% of baseline, from drug administration until end of surgery

  8. Hypertension: systolic blood pressure greater than 120% of baseline

    Time frame: 2 hours

    Systolic blood pressure > 120% of baseline, from drug administration until end of surgery

  9. Tachycardia: heart rate greater than 130% of baseline

    Time frame: 2 hours

    Heart rate > 130% of baseline, from drug administration until end of surgery

  10. Bradycardia: heart rate less than 70% of baseline

    Time frame: 2 hours

    Heart rate < 70% of baseline or a heart rate < 50bpm, from drug administration until end of surgery

  11. Presence of ventricular tachycardia: ECG

    Time frame: 2 hours

    Presence of ventricular tachycardia as recorded by ECG, from drug administration until end of surgery

  12. Presence of atrial fibrillation: ECG

    Time frame: 2 hours

    Presence of atrial fibrillation as recorded by ECG, from drug administration until end of surgery

  13. Presence of atrial flutter: ECG

    Time frame: 2 hours

    Presence of atrial flutter as recorded by ECG, from drug administration until end of surgery

  14. Presence of nausea: questionnaire

    Time frame: 2 hours

    The presence of nausea and number of episodes, from drug administration until end of surgery, as reported by the patient

  15. Presence of vomiting: questionnaire

    Time frame: 2 hours

    The presence of vomiting and number of episodes, from drug administration until end of surgery

  16. Presence of chest pain: questionnaire

    Time frame: 2 hours

    Any presence of chest pain, from drug administration until end of surgery, as reported by the patient

  17. Presence of shortness of breath: questionnaire

    Time frame: 2 hours

    Any presence of shortness of breath, from drug administration until end of surgery, as reported by the patient

  18. Presence of headache: questionnaire

    Time frame: 2 hours

    Any presence of headache, from drug administration until end of surgery, as reported by the patient

Interested in participating?

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Sponsors and collaborators

Lead sponsor

Samuel Lunenfeld Research Institute, Mount Sinai Hospital

Other

Registry information

Important dates

Study start
2022
Primary completion
2026
Study completion
2026
First posted
Mar 22, 2022
Registry last updated
Apr 6, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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