Phenylephrine Prophylaxis for Postspinal Anesthesia Hypotension in Parturients With Preeclampsia

Study Overview
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Brief Summary
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The purpose of this study is to investigate the suitable infusion dose of phenylephrine for prophylaxis against postspinal anesthesia hypotension in parturients with preeclampsia undergoing cesarean section.

Detailed Description
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Preeclampsia, which affects 5% to 7% of parturients, is a significant cause of maternal and neonatal morbidity and mortality. Because of constricted myometrial spiral arteries with exaggerated vasomotor responsiveness, though blood pressure in parturients with preeclampsia are apparently higher than healthy parturients, placental hypoperfusion is more common. Spinal anesthesia is still the preferred mode of anesthesia in parturients with preeclampsia for cesarean section. In preeclampsia parturients, spinal anesthesia improve intervillous blood flow (provided that hypotension is avoided) which contribute to increase placental perfusion. Even so, 17-26% parturients with preeclampsia experienced postspinal anesthesia hypotension due to the extensive sympathetic block that occurred with spinal anesthesia. Practical guidelines for obstetric anesthesia from the American Society of Anesthesiologists and an international consensus statement on the management of hypotension with vasopressors indicate either IV ephedrine or phenylephrine may be used to correct hypotension. But the suitable infusion dose of phenylephrine in parturients with preeclampsia is still unknown. The purpose of this study is to investigate the suitable infusion dose of phenylephrine for prophylaxis against post-spinal anesthesia hypotension in parturients with preeclampsia undergoing cesarean section.

Official Title
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Phenylephrine Prophylaxis for Postspinal Anesthesia Hypotension in Parturients With Preeclampsia Undergoing Cesarean Section: a Randomized, Placebo-controlled Dose-finding Trial

Conditions
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Adverse Effect

Intervention / Treatment
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* Drug: Normal saline
* Drug: Phenylephrine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18-45 years Primipara or multipara Singleton pregnancy ≥32 weeks American Society of Anesthesiologists physical status classification II to III Scheduled for cesarean section under spinal anesthesia Exclusion Criteria: Baseline blood pressure ≥180 mmHg Body height < 150 cm Body weight > 100 kg or body mass index (BMI) ≥ 40 kg/m2 Eclampsia or chronic hypertension Hemoglobin < 7g/dl Fetal distress, or known fetal developmental anomaly

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 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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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Control group<br>Normal saline infusion simultaneous with subarachnoid block | Drug: Normal saline<br>* Normal saline infusion simultaneous with subarachnoid block<br>* Other names: NS;|
| Experimental: 0.3125 μg/kg/min group<br>A maintenance dose of phenylephrine (0.3125 μg/kg/ min) infusion simultaneous with subarachnoid block | Drug: Phenylephrine<br>* Different infusion dose of phenylephrine simultaneous with subarachnoid block<br>* Other names: Vasopressors;|
| Experimental: 0.625 μg/kg/min group<br>A maintenance dose of phenylephrine (0.625 μg/kg/ min) infusion simultaneous with subarachnoid block | Drug: Phenylephrine<br>* Different infusion dose of phenylephrine simultaneous with subarachnoid block<br>* Other names: Vasopressors;|
| Experimental: 0.9375 μg/kg/min group<br>A maintenance dose of phenylephrine (0.9375 μg/kg/ min) infusion simultaneous with subarachnoid block | Drug: Phenylephrine<br>* Different infusion dose of phenylephrine simultaneous with subarachnoid block<br>* Other names: Vasopressors;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The incidence of post-spinal anesthesia hypotension | Systolic blood pressure (SBP) < 80% of the baseline | 1-15 minutes after spinal anesthesia | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Overall stability of systolic blood pressure control versus baseline | Evaluated by performance error (PE) | 1-15 minutes after spinal anesthesia | 
| Overall stability of heart rate control versus baseline | Evaluated by performance error (PE) | 1-15 minutes after spinal anesthesia | 
| The incidence of severe post-spinal anesthesia hypotension | Systolic blood pressure (SBP) < 60% of the baseline | 1-15 minutes after spinal anesthesia | 
| The incidence of nausea and vomiting | Presence of nausea and vomiting in patients after spinal anesthesia | 1-15 minutes after spinal anesthesia | 
| The incidence of bradycardia | Heart rate < 60 beats/min | 1-15 minutes after spinal anesthesia | 
| The incidence of hypertension. | Systolic blood pressure (SBP) >120% of the baseline. | 1-15 minutes after spinal anesthesia | 
| pH | From umbilical arterial blood gases. | Immediately after delivery | 
| Partial pressure of oxygen | From umbilical arterial blood gases. | Immediately after delivery | 
| Base excess | From umbilical arterial blood gases. | Immediately after delivery | 
| APGAR score | A= Appearance P=Pulse G=Grimace A=Attitude R=Respiration | 1 min after delivery | 
| APGAR score | A= Appearance P=Pulse G=Grimace A=Attitude R=Respiration | 5 min after delivery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Phenylephrine, Postspinal anesthesia hypotension, Preeclampsia, Cesarean section, Dose-finding