Postpartum hemorrhage (PPH) is a major cause of maternal death worldwide. Oxytocin is the most commonly used uterotonic drug for the active management of third stage labor, to reduce the risk of PPH and help deliver the placenta. Carbetocin is currently recommended by the SOGC (Society of Obstetricans \& Gynecologists of Canada), and is a relatively newer drug with a longer duration of action. It has been previously demonstrated that women with elevated BMI require higher doses of these drugs to induce adequate uterine contraction and dose finding studies undertaken at Mount Sinai Hospital have shown that the ED 90 in obese patients to be carbetocin 80 mcg and oxytocin 1IU. Furthermore, previous studies have indicated that the use of carbetocin over oxytocin in non-obese popultion is associated with reduced bleeding and requirement of additional uterotonic medications. No study has directly compared the two drugs in obese parturients in a head to head clinical trial; therefore a double-blind randomized controlled trial is necessary to show the non-inferiority of carbetocin against the current standard of care at Mount Sinai hospital, which is oxytocin.
Obesity in pregnancy is defined as a Body Mass Index (BMI) above 30 kg/m2 and is often cited as a risk factor for PPH after cesarean delivery. The World Health organization (WHO) recommends that uterotonic medications are routinely administered at cesarean delivery for the active management of the third stage of labor, both to facilitate delivery of the placenta and to reduce the risk of PPH. The optimal regimen for active management of third stage of labor is yet to be fully determined and obesity adds another layer of complexity and risk, with higher doses required to induce adequate uterine contraction. While oxytocin is the most commonly used drug world-wide, multiple agents are available and there is no clear consensus as to which drug should be first choice. Multiple studies have shown that carbetocin is associated with reduced post-partum bleeding, need for blood transfusion and additional uterotonic medications, in the non-obese population. The results of this study will provide evidence on the non-inferiority of carbetocin when compared directly to the current standard of care at Mount Sinai hospital, which is oxytocin. The investigators hypothesize that when administered in equipotent doses, carbetocin would be non-inferior to oxytocin in women with BMI ≥40 kg/m2 undergoing elective cesarean delivery. The investigators hope to prove that the difference between uterine tone elicited by carbetocin falls within the inferiority margin of -1.2 using a verbal numerical rating score.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
48
Patient is given carbetocin (80mcg) intravenously over 1 minute, immediately upon delivery of the anterior shoulder of the baby.
Patient is given oxytocin (1IU) intravenously over 1 minute, immediately upon delivery of the anterior shoulder of the baby, followed by infusion 80 mU/min (40 IU in 1L given at a rate of 120 mL/h).
Mount Sinai Hospital
Toronto, Ontario, Canada
Uterine Tone 3 minutes
The primary outcome will be the intensity of uterine tone as evaluated by palpation of the uterus by the obstetrician at 3 minutes, from the completion of delivery of the drug, utilising a VNRS scale of 0-10.
Time frame: 3 minutes
Uterine Tone 5 minutes
Intensity of uterine tone on a VNRS scale of 0-10 as evaluated by the obstetrician at 5 minutes after completion of injection of the bolus study drug.
Time frame: 5 min
Uterine Tone 10 minutes
Intensity of uterine tone on a VNRS scale of 0-10 as evaluated by the obstetrician at 10 minutes after completion of injection of the bolus study drug.
Time frame: 10 min
Additional uterotonics - operating room
The use of additional uterotonic agents in the operating room
Time frame: 1-2 hours, length of surgery will vary
Additional uterotonics - Post Anesthesia Care Unit (PACU)
The use of additional uterotonic agents at any time after admission to the recovery area (Post Anesthesia Care Unit (PACU)) until transfer to the post partum ward.
Time frame: 4 hours
Additional uterotonics - 24 hours
The use of additional uterotonic agents at any time after discharge from the recovery area (Post Anesthesia Care Unit (PACU)) and up to 24 hours post delivery
Time frame: 24 hours
Estimated blood loss calculated
Blood loss will be calculated through the difference in hematocrit values assessed prior to and at the end of 24 hours after the cesarean section.
Time frame: 24 hours
Estimated blood loss, visual estimate provided by the obstetrician
Blood loss in ml, as reported by the obstetrician at the end of the surgery.
Time frame: 2 hours
Hypotension: systolic blood pressure less than 80% of baseline
Systolic blood pressure \< 80% of baseline, from drug administration until end of surgery
Time frame: 2 hours
Hypertension: systolic blood pressure greater than 120% of baseline
Systolic blood pressure \> 120% of baseline, from drug administration until end of surgery
Time frame: 2 hours
Tachycardia: heart rate greater than 130% of baseline
Heart rate \> 130% of baseline, from drug administration until end of surgery
Time frame: 2 hours
Bradycardia: heart rate less than 70% of baseline
Heart rate \< 70% of baseline, from drug administration until end of surgery
Time frame: 2 hours
Presence of ventricular tachycardia: ECG
Presence of ventricular tachycardia as recorded by ECG, from drug administration until end of surgery
Time frame: 2 hours
Presence of atrial fibrillation: ECG
Presence of atrial fibrillation as recorded by ECG, from drug administration until end of surgery
Time frame: 2 hours
Presence of atrial flutter: ECG
Presence of atrial flutter as recorded by ECG, from drug administration until end of surgery
Time frame: 2 hours
Presence of nausea: questionnaire
The presence of nausea and number of episodes, from drug administration until end of surgery, as reported by the patient
Time frame: 2 hours
Presence of vomiting: questionnaire
The presence of vomiting and number of episodes, from drug administration until end of surgery
Time frame: 2 hours
Presence of chest pain: questionnaire
Any presence of chest pain, from drug administration until end of surgery, as reported by the patient
Time frame: 2 hours
Presence of shortness of breath: questionnaire
Any presence of shortness of breath, from drug administration until end of surgery, as reported by the patient
Time frame: 2 hours
Presence of headache: questionnaire
Any presence of headache, from drug administration until end of surgery, as reported by the patient
Time frame: 2 hours
Presence of flushing: questionnaire
Any presence of flushing, from drug administration until end of surgery
Time frame: 2 hours
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