Could the Cerebral Oximetry be a Good Technology to Measure Placental Oxygenation?

Study Overview
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Brief Summary
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To assess the potential of the cerebral oximeter to measure placental oxygenation

Detailed Description
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There is general agreement among experts to recommend the use of phenylephrine as first line therapy for the treatment of arterial hypotension induced by spinal anaesthesia during caesarean delivery. In some studies, there are trends toward a lower PaO2 values in the umbilical cord venous blood when the mother receive this vasopressor. These findings may be a result of the vasoconstrictor effect of phenylephrine on utero-placental vessels, and a subsequent increased oxygen extraction by the fetus. The possibility to extract more oxygen would provide a certain safety margin in the event of compromised utero-placental blood flow during normal pregnancy. However, this safety margin should not be taken for granted in cases where signs of fetal distress are present, and this situation might influence the choice of vasopressors. It is well establish on a physiological basis that during labour, utero-placental blood flow is lower during the contractions. This lower blood flow could result in a lower saturation value measured by the cerebral oximeter. Twenty patients in labour will be included in this study. Patients will be recruited in obstetric clinic during pregnancy. Based on the second trimester ultrasound, patients with anterior placenta will be included. During labour, once a functional epidural is in place, an Invos oximeter will be install. Two sensors will be applied on the abdomen (one above the placenta and the other above the myometrium at a place without placenta). Two sensors will also be applied on the extremities (forearm and leg).Saturation values and timing of the contractions will be recorded for sixty minutes. Half of the recording will be done with an oxygen mask. Vitals signs will also be registered every five minutes.

Official Title
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Could the Cerebral Oximetry (NIRS) be a Good Technology to Measure Placental Oxygenation in Pregnant Woman?

Conditions
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Placental Oxygenation

Intervention / Treatment
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* Device: cerebral oximetry


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: healthy pregnant woman (ASA I or II) Term gestation ( > 37 weeks) Normal pregnancy vaginal delivery obstetrical epidural in place anterior placenta Exclusion Criteria: patient refusal Any contraindication to neuraxial anesthesia cesarean section multiple gestation placentation abnormalities anormal placental perfusion Placental Abruption

Ages Eligible for Study
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Minimum Age: 18 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 |
| --- | --- |
| anterior placenta<br>Cerebral oximetry device used to obtain: Saturation value of the placenta probe with no oxygen, saturation value of the placenta probe with oxygen, saturation value of the myometrium probe with no oxygen saturation value of the myometrium probe with oxygen saturation value of the forearm probe with no oxygen, saturation value of the forearm probe with oxygen saturation value of the leg probe with no oxygen saturation value of the leg probe with oxygen Timing between the contractions measure by cardiotocography | Device: cerebral oximetry<br>* tissue saturation measurement in pregnant women<br>* Other names: INVOS;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference between Δp and Δm | Δp = Difference between the mean value area under the curve for the placenta and arm = (Ap- Af) Δm= Difference between the mean value area under the curve for the myometrium and arm = (Am- Af) | 60 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference of the area under the curve of saturation with and without oxygen | Ap with Oxygen - Ap without oxygen; Am with oxygen - Am without oxygen | 60 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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placental oxygenation, obstetric anesthesia, NIRS, cerebral oximetry, cerebral oximeter