In-vitro Study to Assess the Coagulation Effects of Exogenous Oxytocin Using Thromboelastography.

Study Overview
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Brief Summary
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Oxytocin is normally administered following delivery in pregnant patients to reduce postpartum bleeding by increasing uterine tone. It is unclear whether the use of intravenous oxytocin alters coagulation in pregnant patients. The purpose of the in-vitro study is to assess the coagulation changes of oxytocin in blood samples from pregnant patients using thromboelastrography (TEG). TEG is a point-of-care device which measures the viscoelastic properties of clot formation, and can provide rapid and detailed information about coagulation changes. We aim to collect blood samples from pregnant patients to assess the in-vitro effects of synthetic oxytocin on coagulation using TEG.

Detailed Description
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All obstetric patients presenting for elective induction of labor or elective Cesarean delivery will be informed about the study prior to and on admission to the labor and delivery unit. Admission blood sampling will take place by venepuncture for the following analysis:TEG, PT, PTT, INR, Hct, Platelet count.The results of oxytocin influence on thromboelastogram parameters will be compared to a control. The control is an aliquot of parturient blood with no added oxytocin. Thromboelastography will be used to assess coagulation changes between control samples and blood samples with added oxytocin. The results will not be used to influence clinical management of any case.

Official Title
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In-vitro Study to Assess the Coagulation Effects of Exogenous Oxytocin Using Thromboelastography.

Conditions
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Anesthesia

Intervention / Treatment
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* Drug: Final exogenous oxytocin concentration=22.5 μU/mL
* Drug: Final exogenous oxytocin concentration=30.1μU/mL
* Drug: Final exogenous oxytocin concentration=32.9μU/mL


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria:All obstetric patients with singleton pregnancies admitted to the labor and delivery unit at Lucile Packard Childrens Hospital awaiting elective induction of labor or elective Cesarean delivery. We will select 25 healthy ASA 1 patients with singleton pregnancies who are scheduled for uncomplicated elective induction of labor. Gestational age equal to or greater than 37 weeks. Exclusion Criteria:Patients with underlying coagulation disorders. Patients with thrombocytopenia. Patients with pregnancy-induced hypertension, pre-eclampsia. Patients admitted for non-elective cesarean section. Patients in active labor. Patients requiring the following medications prior to surgery: NSAIDS, aspirin, anticoagulants. Patients with significant obstetric or medical disease. No patients <18 years of age will be recruited.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| All participants<br>For each patient, 1 solution with citrated whole blood (control) and 3 solutions with citrated whole blood and exogenous oxytocin were prepared in separate vials using micropipettes as follows: Citrated whole blood 1mL + 23μU oxytocin: final exogenous oxytocin concentration=22.5 μU/mL Citrated whole blood 1mL + 31μU oxytocin: final exogenous oxytocin concentration=30.1μU/mL Citrated whole blood 1mL + 34μU oxytocin: final exogenous oxytocin concentration=32.9μU/mL After mixing by inversion 8-10 times, 360μL kaolin-activated blood of each study solution was pipetted into a plastic cup in a prewarmed Thromboelastograph® (37°C). Each sample was recalcified in a plastic cup with 10μL of CaCl2 6.45%, and TEG® analysis was commenced within 1 minute of reconstituted sample preparation. | Drug: Final exogenous oxytocin concentration=22.5 μU/mL<br>* Citrated whole blood 1mL + 23μU oxytocin. After mixing by inversion 8-10 times, 360μL kaolin-activated blood of each study solution was pipetted into a plastic cup in a prewarmed Thromboelastograph® (37°C). Each sample was recalcified in a plastic cup with 10μL of CaCl2 6.45%, and TEG® analysis was commenced within 1 minute of reconstituted sample preparation.<br>* Other names: TEG;Drug: Final exogenous oxytocin concentration=30.1μU/mL<br>* Citrated whole blood 1mL + 31μU oxytocin. After mixing by inversion 8-10 times, 360μL kaolin-activated blood of each study solution was pipetted into a plastic cup in a prewarmed Thromboelastograph® (37°C). Each sample was recalcified in a plastic cup with 10μL of CaCl2 6.45%, and TEG® analysis was commenced within 1 minute of reconstituted sample preparation.<br>* Other names: TEG;Drug: Final exogenous oxytocin concentration=32.9μU/mL<br>* Citrated whole blood 1mL + 34μU oxytocin. After mixing by inversion 8-10 times, 360μL kaolin-activated blood of each study solution was pipetted into a plastic cup in a prewarmed Thromboelastograph® (37°C). Each sample was recalcified in a plastic cup with 10μL of CaCl2 6.45%, and TEG® analysis was commenced within 1 minute of reconstituted sample preparation.<br>* Other names: TEG;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| r Time | thromboelastographic indices - reaction time (normal range, 5-10 min) | 6 months | 
| k Time | thromboelastographic indices - clot formation time (normal range, 1-3 min) | 6 months | 
| Alpha Angle | thromboelastographic - alpha angle = clot formation rate (normal range, 53 degress to 72 degrees) | 6 months | 
| MA | thromboelastographic indices - maximum amplitude (normal range, 50-70 mm) | 6 months | 
| MRTG | thromboelastographic indices - maximum rate of thrombus generation (normal range, 5-17 mm/min) | 6 months | 
| Tmax | thromboelastographic indices - time to initiation of clot formation plus time to achieve maximum rate of clot strength development (normal range, 6-12 min) | 6 months | 
| TTG | thromboelastographic indices - total thrombus generation (normal range, 584-796 mm) | 6 months |