The Potency of Prophylactic Norepinephrine and Phenylephrine Boluses for Postspinal Anesthesia Hypotension

Study Overview
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Brief Summary
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The purpose of this study is to investigate the potency between prophylactic norepinephrine and phenylephrine boluses for postspinal anesthesia hypotension in patients with severe preeclampsia during caesarean section.

Detailed Description
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Preeclampsia, which affects 5% to 7% of patients, 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 patients with preeclampsia are apparently higher than healthy patients, placental hypoperfusion is more common. Spinal anesthesia is still the preferred mode of anesthesia in patients with preeclampsia for cesarean section. In preeclampsia patients, spinal anesthesia improve intervillous blood flow (provided that hypotension is avoided) which contribute to increase placental perfusion. Even so, 17-26% patients with preeclampsia experienced postspinal anesthesia hypotension due to the extensive sympathetic block that occurred with spinal anesthesia. As a potential substitute drug for phenylephrine and ephedrine, norepinephrine has gained traction for use in patients undergoing cesarean section. However, the ED50 (prevent postspinal hypotension in 50% of patients) and ED90 of prophylactic norepinephrine bolus is still unknown. The purpose of this study is to investigate the potency between prophylactic norepinephrine and phenylephrine boluses for postspinal anesthesia hypotension in patients with severe preeclampsia during caesarean section.

Official Title
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Comparison of the Potency of Prophylactic Norepinephrine and Phenylephrine Boluses for Postspinal Anesthesia Hypotension in Patients With Severe Preeclampsia During Caesarean Section

Conditions
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Adverse Effect

Intervention / Treatment
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* Drug: Phenylephrine
* Drug: Norepinephrine


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: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Phenylephrine group<br>Prophylactic phenylephrine bolus simultaneous with spinal anesthesia | Drug: Phenylephrine<br>* An initial prophylactic bolus dose of phenylephrine (37.5μg) simultaneous with spinal anesthesia. If the patient did not respond adequately to the current dose (SBP decreased to < 80% of baseline), the dose was considered to have failed and the subsequent dose for the following patient was increased to the next higher dose level. The dose administered to subsequent patients varied by increments or decrements of 12.5 μg according to the responses of previous patients according to the up-down sequential allocation.<br>* Other names: Vasopressors;|
| Experimental: Norepinephrine group<br>Prophylactic norepinephrine bolus simultaneous with spinal anesthesia | Drug: Norepinephrine<br>* An initial prophylactic bolus dose of norepinephrine (3μg) simultaneous with spinal anesthesia. The dose administered to subsequent patients varied by increments or decrements of 1 μg according to the responses of previous patients according to the up-down sequential allocation.<br>* Other names: Vasopressors;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The dose that would be effective in preventing postspinal anesthesia hypotension in 50% (effective dose, ED 50) and 90% (ED90) of patients | Systolic blood pressure (SBP) < 80% of the baseline | 1-15 minutes after spinal anesthesia | 

Secondary 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 | 
| 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 bradycardia. | Heart rate < 60 beats/min. | 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 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 (PO2) | From umbilical arterial blood gases. | Immediately after delivery | 
| Base excess (BE) | 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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Norepinephrine, Phenylephrine, Postspinal anesthesia hypotension, Preeclampsia, Cesarean section