Oxytocin at Elective Cesarean Deliveries: A Dose-finding Study in Women With BMI ≥ 40kg/m2
Condition: Postpartum Hemorrhage; Obesity
MeSH terms: Postpartum Hemorrhage; Hemorrhage
Study type: Interventional

Summary: 
      Postpartum hemorrhage (PPH) due to uterine atony is a major cause of maternal morbidity and
      mortality. Uterotonic drugs are used to improve the muscle tone of the uterus after birth,
      and these are effective at reducing the incidence of PPH. Oxytocin is the most commonly used
      uterotonic drug to prevent and treat PPH. Large doses of this drug are asociated with adverse
      effects like low blood pressure, nausea, vomiting, abnormal heart rhythms and changes on ECG.
      Various international bodies recommend varying and high doses of oxytocin in elective
      cesarean sections. A study performed at Mount Sinai Hospital showed that a much smaller dose
      of oxytocin is required (ED95 being 0.35IU). However, most of the women included in this
      study were below a body mass index (BMI) of 40kg/m2.

      The investigators seek to find the best dose for patients with a BMI>40kg/m2, as a higher
      dose may be needed in this population to contract the uterus adequately.
    

Detailed description: 
      Postpartum hemorrhage (PPH) is one of the leading causes of death during childbirth and
      accounts for an estimated 140,000 deaths per year worldwide. The World Health Organization
      (WHO) recommends active management of the third stage of labor to prevent PPH, even in low
      risk patients. Prophylactic uterotonic drugs administered after delivery are the main element
      of active management of the third stage and have been demonstrated to reduce the incidence of
      PPH by up to 40%. Oxytocin is the most commonly used uterotonic in North America, however it
      has a very short duration of action and requires a continuous infusion to achieve sustained
      effect, with large doses associated with adverse effects like low blood pressure, nausea,
      vomiting, abnormal heart rhythms and changes on ECG.

      The prevalence of obesity is increasing in young women and some studies have shown that obese
      women have higher rates of caesarean delivery compared to non-obese women. Other studies have
      demonstrated an increased risk of hemorrhage due to poor uterine tone in obese women.
      Laboratory studies show that BMI alone appears to contribute to blunted uterine muscle
      responses and therefore contraction responses to oxytocin in obese women.

      Previous dose finding studies have excluded those women with a BMI of ≥40kgm2. Therefore, the
      investigators wish to perform a double-blind dose finding study using the biased coin
      up-and-down sequential allocation technique to determine the ED90 of oxytocin at cesarean
      section in those women with a BMI>40.
    

Intervention name(s): Oxytocin
Intervention type(s): Drug
Intervention description(s): Oxytocin administered intravenously, over 1 minute following delivery of the fetal head
Other intervention name(s): pitocin
Intervention MeSH terms: Oxytocin
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Biased coin up-and-down design.
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: pregnancy; postpartum hemorrhage; Cesarean delivery; oxytocin; obesity