Oxytocin Bolus Versus Infusion in Elective Cesarean Section" (INBOX)

Stony Brook University

Status and phase: Enrolling; Phase 4

Conditions: Elective Cesarean Section

Treatments: Drug: Oxytocin bolus or oxytocin infusion

Study type: Interventional

Funder types: Other

Identifiers

NCT05236985

IRB 2021-00558

Details and patient eligibility

About

Bolus administration of oxytocin is superior to infusion in time to achieving adequate uterine tone.

Full description

Oxytocin is the most commonly used uterotonic agent worldwide to achieve adequate uterine tone and prevent postpartum hemorrhage. Over the past decade, the trend has been towards lowering the dose to reduce oxytocin-related adverse effects including nausea, hypotension, chest pain, EKG changes, and maternal death. However, the optimal strategy for oxytocin administration remains controversial. Prior literature found bolus doses less than 5 IU to be effective in achieving adequate uterine tone with a significant reduction in adverse side effects. There is limited high quality data comparing bolus versus infusion administration of oxytocin. The current standard of care at the institution is an infusion of oxytocin 18 IU/hour (0.3 IU/min) and has been proven to be effective in achieving adequate uterine tone. However, the time to uterine tone appears to be slightly longer (3-4 mins) with the infusion method. Given that the estimated uterine blood flow is between 500-700 mls/min, the uterus can lose a significant amount of blood per second if uterine tone is not achieved quickly. Thus, the purpose of this research study is to compare bolus and infusion administration of oxytocin on parturients undergoing elective cesarean section. The primary objective of this study is to test the hypothesis that administration by bolus (vs. standard of care infusion) results in more rapid achievement of adequate uterine tone. Secondary objectives include determining estimated blood loss, prevalence of hypotension, nausea, vomiting, and patient satisfaction.

Enrollment: 120 estimated patients

Sex: Female

Ages: 18 to 45 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Parturients between the ages of 18 to 45 with singleton pregnancies
• Undergoing elective cesarean section under spinal anesthesia
• American Society of Anesthesia (ASA) physical status class I or II
• Patients must be able to provide written informed consent

Exclusion criteria

• Parturients in labor or ruptured membranes
• Multiple gestation
• Risk factors predisposing to uterine atony (history of placenta previa, preeclampsia, diabetes mellitus macrosomia, hydramnios, bleeding diathesis, uterine fibroids)
• History of uterine atony or postpartum hemorrhage
• History of inherited or acquired coagulation disorders, thrombocytopenia (platelet count <100), or anemia (hemoglobin < 8)
• History of allergy to oxytocin
• Patients not alert and orientated to person, place, and date. Patient must have, in the investigator's opinion, the physical and mental capacity to answer survey questions

Trial design

Primary purpose: Other

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Triple Blind

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120 participants in 2 patient groups

Bolus arm

Active Comparator group

Description:

Patients will receive 3 IU oxytocin IV bolus over 15 seconds after delivery of the baby/uterine cord clamping and a maintenance infusion of 0.9% Saline will be started at 225ml/hr. If uterine tone is inadequate after 3 minutes, a second bolus of 3 IU oxytocin will be given. If uterine tone is inadequate after an additional 3 minutes, a third bolus of 3 IU Oxytocin IV is given over 15 seconds. If after an additional 3 mins uterine tone is still inadequate, a second infusion consisting of oxytocin 3 IU/hr is started at 100ml/hrs and continued for a total of 4 hours, second line uterotonic agents (Methergine, Hemabate and/ or Cytotec) will be given, and the maintenance 0.9% Saline infusion will be changed to 450 ml/hr for a total of 1 hour, then changed to 38 ml/ hour for the following 3 hours. If uterine tone is considered adequate at 3, 6 or 9 minutes, a second infusion of oxytocin 3 IU/hr (100ml/hr) is started and maintained for 4 hours.

Treatment:

Drug: Oxytocin bolus or oxytocin infusion

Infusion arm

Active Comparator group

Description:

Patients will receive a bolus of IV 0.9% Saline over 15 seconds after delivery of the baby/uterine cord clamping and a maintenance infusion of 18 IU/hr Oxytocin IV (225ml/hr). If uterine tone is inadequate after 3 minutes, a second bolus of 0.9% Saline will be given. If uterine tone is inadequate after another 3 minutes, a third bolus of 0.9% Saline will be given. If after another 3 mins uterine tone is inadequate, a second infusion of 0.9% Saline will be started for 4 hours, second line uterotonic agents (Methergine, Hemabate and/or Cytotec) will be given, and the Oxytocin infusion will be changed to 36 IU/hour (450 ml/hr) for a total of 1 hour, and then changed to 38 ml/hr for the following 3 hours. If uterine tone is considered adequate at 3, 6 or 9 minutes, a second infusion of 0.9% Saline at 100 ml/hr will be started and maintained for 4 hours, along with the maintenance infusion of 18 IU/hr (225 ml/ hr) for a total of 1 hour, then changed to 38 ml/hr for an additional 3 hours.

Treatment:

Drug: Oxytocin bolus or oxytocin infusion