Comparison of Two Doses of Norepinephrine in Preventing Hypotension After Spinal Anesthesia

Study Overview
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Brief Summary
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The purpose of the study is to determine the more effective intravenous bolus of norepinephrine for maintaining blood pressure during a spinal anesthesia for a cesarean delivery with the fewer side effects. Low blood pressure has been shown to decrease uterine perfusion and foetal outcomes during cesarean delivery under spinal anesthesia. For elective or semi-urgent cesarean delivery, all participants will receive spinal anesthesia with a local anesthetic and either sufentanil or fentanyl. This study plans to enroll 124 pregnant women. Patients will be randomly assigned according to a computer generated system to be in one of two groups.

Detailed Description
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This study will be a prospective, randomized, active treatment controlled trial. After written and informed consent, the study participants will be randomly assigned using a computer generated table to 1 of 2 treatment groups prior to cesarean delivery. Group A will receive an intravenous bolus of 1mcg/Kg of norepinephrine bitartrate to maintain systolic blood pressure (SBP) within 80-120% of baseline before the spinal anesthesia. Group B will receive an intravenous bolus of 0.5mcg/kg of norepinephrine bitartrate to maintain systolic blood pressure (SBP) within 80-120% of baseline before the spinal anesthesia. Patients will be admitted to holding area. Baseline arterial blood pressure and heart rate will be measured in supine position, with left uterine displacement. Baseline blood pressure will be calculated as the mean of three consecutive SBP measurements taken 3 minutes apart. 500 mL of Lactated Ringers solution will be administered immediately after induction of spinal anesthesia at the outflow rate of 100ml per hour. The primary endpoints are: the timing of the first maternal hypotension before delivery (defined as a decrease of SBP >20% of baseline and/or PAS<100mmHg) the delta PAS and delta PAM before delivery ( difference between basline and the lowest systolic and mean blood pressure respectively) The secondary endpoints are: Incidence of hypotension,norepinephrine consumption (mean dose of Norepinephrine to maintain blood pressure between 80 and 100 % of baseline values after the primary preventive bolus), nausea and vomiting will be recorded whenever present during the surgical procedure as well as reactive hypertension (defined as a rise of SBP >20% of baseline or SBP>140mmHg) and arrhythmia. Bradycardia (HR less than 50 BPM) will be treated with Atropine 0.5mg IV. Fetal cord blood analysis will be done immediately after delivery in order to determine the pH value ( ie : logarithm of the blood concentration of hydrogen ions H+)in each group Study participants will receive a standard spinal anesthetic consisting of 0.5% hyperbaric bupivacaine (2 mL) with either sufentanil (5 mcg) or fentanyl (50 mcg) at L3-4 or L4-5. Prior to surgical incision, the spinal sensory level will be tested to the bilateral T6-T4 dermatomal level. The patients will be positioned supine with a wedge placed under the right hip to avoid aortocaval compression. Both the patient and the researcher's assistant (who will collect data) will be blinded as to the administered Norepinephrine bolus A or B. When PAS<80% of baseline or < 100 mmHg a bolus of Norepinephrine will be administrated(half dose A or B). The study will end when cesarean section is completed and the patient transferred to the post-operative care unit. Measured variables will include systolic, diastolic and mean non-invasive blood pressure, heart rate, number of rescue boluses , incidence of nausea and vomiting (NV), incidence of arrhythmia, Apgar score and fetal cord blood analysis (pH) at delivery.

Official Title
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Comparison of Two Doses of Norepinephrine in Preventing Hypotension After Spinal Anesthesia for Cesarean Section

Conditions
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Anesthesia, Adverse Effect, Hypotension, Cesarean Section Complications, Vasopressor

Intervention / Treatment
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* Drug: Norepinephrine: 1mcg/kg
* Drug: Norepinephrine 0,5mcg/kg


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Elective or semi-urgent CD under spinal anesthesia Age over 18 years Healthy singleton pregnancy beyond 36 weeks' gestation American Society of Anesthesiologists (ASA) physical status classification 2 Weight 50 to 100 kg, and height 150 to 180 cm Exclusion Criteria: Emergency CD red code Allergy or hypersensitivity to norepinephrine or sulfite Preexisting or pregnancy-induced hypertension, preeclampsia, eclampsia, the use of cardiac medication or medication for blood pressure control multiple gestation Cardiovascular or cerebrovascular disease Fetal abnormalities Suspicion of abnormal placentation History of diabetes mellitus (excluding gestational diabetes) Use of monoamine oxidase inhibitors, triptyline or imipramine antidepressants documented history of postoperative nausea and vomiting, previous gastric bypass surgery, history of chronic opioid use (chronic pain syndrome) Patient refusal

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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Accepts Healthy Volunteers

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 |
| --- | --- |
| Active Comparator: A<br>group A: will receive 1 mcg/Kg of Norepinephrine intravenously | Drug: Norepinephrine: 1mcg/kg<br>* intervention:Parturients will receive Norepinephrine: a bolus of 1 mcg/Kg immediately after SA (preventive bolus) then they will receive complementary doses of Norepinephrine (half dose: 0.5 mcg/Kg) to maintain systolic blood pressure above 80 % of baseline<br>* Other names: Noradrenaline;|
| Active Comparator: B<br>group B: will receive 0.5 mcg/Kg of Norepinephrine intravenously | Drug: Norepinephrine 0,5mcg/kg<br>* intervention: Parturients will receive Norepinephrine: a bolus of 0.5 mcg/Kg immediately after SA (preventive bolus) then they will receive complementary doses of Norepinephrine (half dose: 0.25 mcg/Kg) to maintain systolic blood pressure above 80 % of baseline<br>* Other names: Noradrenaline;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time to administartion of the first rescue bolus | timing of the first hypotension(defined as a decrease of SBP >20% of baseline and/or PAS<100mmHg) recsue bolus will be given at that moment | time from immediately after spinal anesthesia until delivery | 
| systolic blood pressure variation | difference between the baseline systolic blood pressure (PAS0) and the lowest systolic blood pressure (PASmin) registred before delivery and computed as (PAS min -PAS0)/PAS0 | time from immediately after spinal anesthesia until delivery | 
| mean blood pressure variation | difference between the baseline mean blood pressure(PAM0) and the lowest mean blood pressure (PAMmin) registred before delivery and computed as (PAM min -PAM0)/PAM0 | time from immediately after spinal anesthesia until delivery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of hypotension | incidence of hypotension after the primary preventive bolus | tile from right after spinal anesthesia until delivery | 
| Norepinephrine consumption | Mean dose of Norepinephrine ( micrograms) given to maintain blood pressure between 80 and 100 % of baseline values after the primary preventive bolus | time fro right after spinal anesthesia until the end of surgery | 
| Nausea | Incidence of nausea. Measure will be done according to a simple scale: 0= no nausea; 1= nausea [Time | time of surgery (right after spinal anesthesia until end of surgery) | 
| Vomiting | incidence of Vomiting (V) during cesarean section with an infusion of a bolus Norepinephrine. Measure will be done according to a simple scale: 0= no vomiting; 1= vomiting | time of surgery (right after spinal anesthesia until end of surgery) | 
| arrhythmia | incidence of arrhythmic events during cesarean section with an infusion of a bolus of Norepinephrine | time of surgery (right after spinal anesthesia until end of surgery) | 
| Hypertension | a rise of systolic blood pressure (SBP)>20% of baseline or SBP>140mmHg | right after spinal anesthesia until end of surgery)] | 
| mean pH of the fetal cord blood | Fetal cord blood analysis will be done immediately after delivery in order to determine the pH value ( ie : logarithm of the blood concentration of hydrogen ions H+)in each group | time of birth | 
| Apgar score | apgar at 1 and 5 minutes Apgar at 1 and 5 minutes | at time of birth | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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spinal anesthesia, blood pressure, norepinephrine, Cesarean Section