Three Protocols for Phenylephrine Administration in Cesarean Delivery

Study Overview
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Brief Summary
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The investigators will compare variable infusion of phenylephrine (at a starting rate of 0.75 mcg/Kg/min) with fixed rate (0.75 mcg/Kg/min which will stop of reactive hypertension occurred) and single shot (1.5 mcg/Kg) phenylephrine.

Detailed Description
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Maternal hypotension is a common complication after spinal anesthesia for cesarean delivery (CD). Phenylephrine (PE) is the most popular vasopressor for prevention of post-spinal hypotension (PSH) during CD; however, the most appropriate protocol for PE administration is still unknown. The most common PE protocols used for prophylaxis against PSH are: single shot, fixed infusion, and variable infusion. A recent study reported that a dose of 1.5 mcg/Kg is the most suitable single-shot dose for prophylaxis. Another randomized controlled trial compared four doses of PE infusion and reported that 25 mcg/Kg/min and 50 mcg/Kg/min doses were the best doses for fixed infusion with accepted incidence of both PSH as well as reactive hypertension. Using variable infusion rate of PE had been recently introduced in another study with a starting dose of 0.75 mcg/Kg/min. The variable rate infusion showed very good results regarding PSH. In this study, the investigators will compare variable infusion of PE (at a starting rate of 0.75 mcg/Kg/min) with fixed rate (0.75 mcg/Kg/min which will stop if reactive hypertension occurred) and single shot protocol (1.5 mcg/Kg).

Official Title
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Three Protocols for Phenylephrine Administration for Prophylaxis Against Post-spinal Hypotension During Cesarean Delivery

Conditions
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Cesarean Section Complications, Spinal Anesthesia

Intervention / Treatment
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* Drug: Single shot phenylephrine
* Drug: Fixed infusion phenylephrine.
* Drug: Variable infusion phenylephrine.
* Drug: Bupivacaine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Full term Pregnant women Scheduled for cesarean delivery Exclusion Criteria: Pre-eclampsia Eclampsia Hemorrhage Cardiac dysfunction Baseline low heart rate (below 60 bpm)

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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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Single shot<br>Spinal anesthesia will be performed using intrathecal bupivacaine. Then, a single shot phenylephrine (1.5 ug/Kg) will be administered. | Drug: Single shot phenylephrine<br>* A single shot of phenylephrine (1.5 mcg/Kg) will be administrated intravenously.<br>* Other names: Phenylephrine;Drug: Bupivacaine<br>* Bupivacaine will be administrated in the subarachnoid space for spinal anesthesia.<br>* Other names: Marcaine;|
| Active Comparator: Fixed infusion<br>Spinal anesthesia will be performed using intrathecal bupivacaine. Then, fixed infusion phenylephrine will be administered at a dose of (0.75 mcg/Kg/min). the infusion will stop if reactive hypertension occurred. | Drug: Fixed infusion phenylephrine.<br>* Fixed infusion of phenylephrine will be administrated at a rate of 0.75 mcg/Kg/min<br>* Other names: Phenylephrine;Drug: Bupivacaine<br>* Bupivacaine will be administrated in the subarachnoid space for spinal anesthesia.<br>* Other names: Marcaine;|
| Active Comparator: Variable infusion<br>Spinal anesthesia will be performed using intrathecal bupivacaine. Then, variable infusion phenylephrine will be administered at a starting dose of (0.75 mcg/Kg/min). the infusion will be titrated according to blood pressure. | Drug: Variable infusion phenylephrine.<br>* Variable infusion of phenylephrine will be administrated at a starting rate of 0.75 mcg/Kg/min.<br>* Other names: Phenylephrine;Drug: Bupivacaine<br>* Bupivacaine will be administrated in the subarachnoid space for spinal anesthesia.<br>* Other names: Marcaine;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of Post-spinal anesthesia hypotension | Defined as percentage of patients with decreased systolic blood pressure less than 80% of the baseline reading during the period from intrathecal injection to delivery of the fetus | 30 minutes after spinal anesthesia | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of severe Post-spinal anesthesia hypotension | Defined as percentage of patients with decreased systolic blood pressure less than 60% of the baseline reading during the period from intrathecal injection to delivery of the fetus. | 30 minutes after spinal anesthesia | 
| Incidence of reactive hypertension | Defined as percentage of patients with increased systolic blood pressure more than 80% of the baseline reading during the period from intrathecal injection to delivery of the fetus. | 2 hours after spinal anesthesia | 
| Systolic blood pressure | Systolic blood pressure measured in mmHg | 2 hours after spinal anesthesia | 
| Diastolic blood pressure | Diastolic blood pressure measured in mmHg | 2 hours after spinal anesthesia | 
| Heart rate | number of heart beats per minute | 2 hours after spinal anesthesia | 
| APGAR score | APGAR score of the fetus | 10 minutes after delivery | 
| umbilical arterial PH | the PH in umbilical arterial blood | 10 minutes after delivery | 
| umbilical arterial Pco2 | umbilical arterial Pco2 measured in mmHg | 10 minutes after delivery |