Recovery of Oxytocin Responsiveness in Pregnant Human Myometrial Explants After Oxytocin-Induced Desensitization

Postpartum Hemorrhage Clinical Trial

Official title:

Recovery of Oxytocin Responsiveness in Pregnant Human Myometrial Explants After Oxytocin-Induced Desensitization

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT02051231
• Other study ID #: 14-01
• Status: Completed
• Phase: N/A
• First received: January 29, 2014
• Last updated: May 22, 2015
• Start date: December 2013
• Est. completion date: June 2014

Study information

• Verified date: May 2015
• Source: Samuel Lunenfeld Research Institute, Mount Sinai Hospital
• Contact: n/a
• Is FDA regulated: No
• Health authority: Canada: Ethics Review Committee
• Study type: Interventional

Clinical Trial Summary

Postpartum hemorrhage (PPH) is a leading cause of maternal morbidity and mortality worldwide and is caused most commonly by poor uterine muscle tone after delivery. The first line agent used in the prevention and treatment of PPH is oxytocin, which acts by binding with oxytocin receptors (OTR) found on myometrial cells to cause uterine contraction.

Women who require augmentation of labour with oxytocin because of inadequate labour progression are at increased risk of PPH because they have received intravenous oxytocin which exposes the uterus (and OTR) to doses greater than would normally be found without medical intervention. This exposure results in OTR desensitization and decreased uterine sensitivity to oxytocin which may lead to the use of much higher doses of oxytocin (up to 9x) or other agents for preventing and treating PPH with the potential for causing serious drug-related morbidity or fatality to the mother.

Currently, in women who have failed labour augmentation and need to have a Cesarean delivery, it is not known if it would be beneficial to wait a certain period of time after discontinuing intravenous oxytocin before proceeding with the operation. The goal of the waiting time would be to allow the OTRs to recover and resensitize the uterus to the effects of oxytocin to avoid the need for high doses or additional uterus-contracting agents.

Our hypothesis is that there will be a positive correlation between the magnitude of recovery of the myometrium's response to oxytocin and the time elapsed from the desensitizing oxytocin pretreatment (simulated labour augmentation).

Description:

The investigators have previously established an in vitro model of labour augmentation and myometrial desensitization using pregnant human myometrium and an isometric tension recording device. The investigators propose to use this model in order to characterize the time course of recovery of oxytocin-desensitized myometrium to oxytocin sensitivity. These results will help in establishing whether myometrial recovery can occur within a clinically relevant time period, how much sensitivity is recovered, and the duration required.

In the clinical setting of failed labour augmentation and OTR desensitization, it is not known if it is beneficial to wait a certain period of time after discontinuing intravenous oxytocin before proceeding to Cesarean section to allow for resensitization of the myometrium to oxytocin. The results of this study will provide insight into the time course of recovery of the myometrium using an in vitro model of failed labour augmentation. Based on the oxytocin dose-response curves after variable periods of time of "rest", the investigators will be able to determine the degree of recovery of myometrial contractility over time and whether this will occur in a clinically relevant time period for implementation into clinical practice.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 22
• Est. completion date: June 2014
• Est. primary completion date: June 2014
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Female
• Age group: 18 Years to 55 Years

Eligibility

Inclusion Criteria:

• Patients who give written consent to participate in this study

• Patients with gestational age 37-41 weeks

• Non-laboring patients, not exposed to exogenous oxytocin

• Patients requiring primary Cesarean section or first repeat Cesarean section

Exclusion Criteria:

• Patients who refuse to give written informed consent

• Patients who require general anesthesia

• Patients who had previous uterine surgery or more than one previous Cesarean section

• Patients with a multiple pregnancy (more than one fetus)

• Patients with any condition predisposing to uterine atony and postpartum hemorrhage, such as abnormal placentation, multiple gestation, preeclampsia, macrosomia, polyhydramnios, uterine fibroids, bleeding diathesis, chorioamnionitis, or a previous history of postpartum bleeding

• Emergency Cesarean section in labor

• Patients with bleeding disorders

Study Design

Allocation: Non-Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment

Related Conditions & MeSH terms

• Postpartum Hemorrhage

Intervention

Drug:
• Oxytocin
Oxytocin, 10-10mol/L to 10-5mol/L

Locations

Country	Name	City	State
Canada	Mount Sinai Hospital	Toronto	Ontario

Sponsors (1)

Lead Sponsor	Collaborator
Samuel Lunenfeld Research Institute, Mount Sinai Hospital

Country where clinical trial is conducted

Canada, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Amplitude of contraction		2-4 hours	No
Secondary	frequency of contraction		2-4 hours	No
Secondary	Integrated area under response curve (AUC)		2-4 hours	No
Secondary	basal tone		2-4 hours	No