ED90 of Norepinephrine and Phenylephrine Boluses Under Intensive Treatment

Study Overview
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Brief Summary
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The objective of this study is to investigate the ED90 of norepinephrine and phenylephrine boluses for treating postspinal anesthesia hypotension under intensive treatment during cesarean section

Detailed Description
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Post-spinal anesthesia hypotension is a frequent complication during spinal anesthesia for cesarean section. The incidence of post-spinal anesthesia hypotension is as high as 62.1-89.7% if prophylactic measures are not taken. The 2016 ASA guidelines for obstetric anesthesia suggest avoiding hypotension following spinal anesthesia in women and emphasize the use of vasopressors, specifically alpha-receptor agonists, as the preferred strategy to prevent and manage post-spinal anesthesia hypotension. The 2018 International Consensus in the United Kingdom and Northern Ireland recommends maintaining maternal systolic blood pressure above 90% of the baseline value following lumbar anesthesia, while avoiding dropping below 80% of the baseline value. Currently, the threshold for maintaining blood pressure above 80% of the baseline value is widely adopted as a standard; however, limited evidence supports the advantage of sustaining maternal blood pressure above 90% of the baseline value. The objective of this study is to investigate the ED90 of norepinephrine and phenylephrine boluses for treating postspinal anesthesia hypotension under intensive treatment during cesarean section

Official Title
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ED90 of Norepinephrine and Phenylephrine Boluses for Treating Postspinal Anesthesia Hypotension Under Intensive Treatment During Cesarean Section

Conditions
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Adverse Effect

Intervention / Treatment
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* Drug: Norepinephrine
* Drug: Phenylephrine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18-45 years Primipara or multipara Singleton pregnancy ≥37 weeks American Society of Anesthesiologists physical status classification I to II Scheduled for cesarean section under spinal anesthesia Exclusion Criteria: Body height < 150 cm Body weight > 100 kg or body mass index (BMI) ≥ 40 kg/m2 Eclampsia or chronic hypertension or baseline blood pressure ≥180 mmHg 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 |
| --- | --- |
| Experimental: Norepinephrine group<br>The maternal systolic blood pressure was consistently maintained above 90% of the preoperative baseline value from the initiation of spinal anesthesia until fetal delivery. | Drug: Norepinephrine<br>* An initial infusion dose of prophylactic norepinephrine (6 ug) simultaneous with spinal anesthesia. The dose administered to subsequent patients varied by increments or decrements of 1 ug of prophylactic norepinephrine according to the responses of previous patients according to the up-down sequential allocation.<br>* Other names: Vasopressor;|
| Experimental: Phenylephrine group<br>The maternal systolic blood pressure was consistently maintained above 90% of the preoperative baseline value from the initiation of spinal anesthesia until fetal delivery. | Drug: Phenylephrine<br>* An initial infusion dose of prophylactic phenylephrine (75 ug) simultaneous with spinal anesthesia. The dose administered to subsequent patients varied by increments or decrements of 12.5 ug of prophylactic phenylephrine according to the responses of previous patients according to the up-down sequential allocation.<br>* Other names: Vasopressor;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| ED50 and ED90 | The doses of prophylactic norepinephrine and phenylephrine that would be effective in preventing postspinal anesthesia hypotension in 50% (effective dose, ED 50) and 90% (ED90) of patients | 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 | 
| Base excess | From umbilical arterial blood gases. | Immediately after delivery | 
| Partial pressure of oxygen (PO2) | From umbilical arterial blood gases. | Immediately after delivery | 
| APGAR score | A= Appearance P=Pulse G=Grimace A=Attitude R=Respiration; 0(Worst)-10(Best) | 1 min after delivery | 
| APGAR score | A= Appearance P=Pulse G=Grimace A=Attitude R=Respiration; 0(Worst)-10(Best) | 5 min after delivery |