Effect of 90% Effective Dose of Metaraminol in Supine and Left Tilt Positions on Cesarean Section

Study Overview
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Brief Summary
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For hypotension after spinal anesthesia, metaraminol has different 90% effective doses in the supine position and the left-tilt position. We plan to conduct a non-inferiority trial to compare the effects of the two on the fetus and the mother.

Official Title
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Effect of 90% Effective Dose of Metaraminol in Supine and Left Tilt Positions on Cesarean Section：A Non-inferiority Trial

Conditions
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Cesarean Section Complications

Intervention / Treatment
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* Drug: Metaraminol 2.7μg/kg/min
* Drug: Metaraminol 2μg/kg/min


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Singleton pregnancy at term scheduled to be delivered via elective cesarean delivery; height 150-180 cm; American Society of Anesthesiologists (ASA) physical status II-III; body mass index (BMI) <35 kg/m2. Exclusion Criteria: transverse presentation, fetal macrosomia; uterine abnormalities (eg, large fibroids, bicornuate uterus); polyhydramnios; ruptured membranes, oligohydramnios; intrauterine growth restriction; gestational or nongestational hypertension, diabetes, or eclampsia; hypertensive disorders or any condition associated with autonomic neuropathy (such as diabetes mellitus for >10 years) or renal failure; contraindications for combined spinal-epidural anesthesia; participants who declined to sign informed consent forms.

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: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: left-tilt group<br>After spinal anesthesia, the patient was placed in a 15° left position until the fetus was delivered, and metaraminol was given at an initial rate of 2.00μg/kg/min throughout the process. | Drug: Metaraminol 2μg/kg/min<br>* After spinal anesthesia, the patient was placed in left-tilt position until the fetus was delivered, and metaraminol was given at an initial rate of 2μg/kg/min throughout the process.<br>|
| Experimental: supine group<br>After spinal anesthesia, the patient was placed in a supine position until the fetus was delivered, and metaraminol was given at an initial rate of 2.7μg/kg/min throughout the process. | Drug: Metaraminol 2.7μg/kg/min<br>* After spinal anesthesia, the patient was placed in a supine position until the fetus was delivered, and metaraminol was given at an initial rate of 2.7μg/kg/min throughout the process.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Umbilical artery blood pH | pH value of fetal umbilical artery blood | 30 seconds after delivery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| hypotension | Number of Participants with systolic blood pressure reduction >20% baseline value or systolic blood pressure <90 mm Hg before delivery | Intraoperative | 
| bradycardia | Number of Participants with heart rate was ≤50 bpm before delivery Number of Participants with heart rate was ≤50 bpm before delivery Number of Participants with heart rate was ≤50 bpm before delivery | Intraoperative | 
| The incidence of nausea in pregnant women | Anesthesiologist observes combined patient dictation. | Intraoperative | 
| Umbilical artery blood base excess | base excess of fetal umbilical artery blood | 30sec after delivery | 
| The incidence of vomiting in pregnant women | Anesthesiologist observes combined patient dictation | Intraoperative |