Best Regimen for Phenylephrine Administration During Cesarean Section

Study Overview
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Brief Summary
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During Cesarean delivery, phenylephrine is used to maintain the patient's blood pressure. Low blood pressure is the most common side effect of the spinal medication used to anesthetize the patient prior to the start of surgery. This low blood pressure can also trigger unpleasant side effects such as nausea, vomiting and low Apgar scores for the baby. Currently there are 2 methods of phenylephrine administration during Cesarean section. One method is by intermittent bolus and the other is by continuous infusion. It is ideal to have a regimen for phenylephrine administration that maintains blood pressure without compromising cardiac output. In this study, cardiac output and blood pressure will be measured by transthoracic bioimpedance, which is a new technique of noninvasive continuous cardiac output monitoring. The hypothesis of this study is that the continuous infusion of phenylephrine will be equally effective in maintaining blood pressure as compared to the intermittent injection, and will induce less hemodynamic changes.

Official Title
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Study to Determine the Best Regimen for Administration of Phenylephrine During Spinal Anesthesia for Cesarean Delivery, as Determined by Maternal Blood Pressure and Cardiac Output

Conditions
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Cesarean Section, Cardiac Output, Hypotension

Intervention / Treatment
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* Drug: Phenylephrine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Ability to communicate in English Elective Cesarean Delivery under spinal anesthesia Normal singleton pregnancy beyond 36 weeks gestation ASA physical status I/II Weight 50-100 kg, height 150-180 cm Age over 18 years Exclusion Criteria: Patient refusal Inability to communicate in English Allergy or hypersensitivity to phenylephrine Preexisting or pregnancy-induced hypertension Cardiovascular or cerebrovascular disease Fetal abnormalities History of diabetes, excluding gestational diabetes Contra-indications for spinal anesthesia

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Phenylephrine Intermittent Bolus<br>Bolus syringe will contain 120 micrograms/mL of phenylephrine. Infusion solution bag will contain placebo (saline solution). | Drug: Phenylephrine<br>* phenylephrine 120 micrograms/mL, administered either by continuous infusion or by intermittent bolus dose<br>|
| Active Comparator: Phenylephrine Continuous Infusion<br>Infusion solution bag will contain 120 micrograms/mL of phenylephrine. Bolus syringe will contain placebo (saline solution). | Drug: Phenylephrine<br>* phenylephrine 120 micrograms/mL, administered either by continuous infusion or by intermittent bolus dose<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The maximum decrease in cardiac output in the pre-delivery period. |  | 30 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Maximum decrease in heart rate in the pre-delivery period. |  | 30 minutes | 
| Incidence of hypotension in the pre-delivery period (BP < 80% baseline) |  | 30 minutes | 
| Incidence of hypertension in the pre-delivery period (BP > 120% baseline) |  | 30 minutes | 
| Incidence of nausea and vomiting in the pre-delivery period |  | 30 minutes | 
| Total dose of phenylephrine in the pre-delivery period |  | 30 minutes | 
| Umbilical artery and vein blood gases |  | 24 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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transthoracic bioreactance, noninvasive monitoring, vasopressor, blood pressure