Norepinephrine vs. Phenylephrine for Hypotension in Low-Dose Spinal Anesthesia for Cesarean Delivery (NORPHE-CD)

Comparison of Continuous Norepinephrine and Phenylephrine Infusion for Preventing Hypotension During Low-Dose Spinal Anesthesia in Cesarean Delivery: A Randomized Controlled Trial

This clinical trial was conducted to compare the effectiveness and safety of two medications, norepinephrine and phenylephrine, in preventing hypotension during low-dose spinal anesthesia for cesarean delivery (CD). Although low-dose spinal anesthesia combined with opioids is widely used to mitigate hypotension, the incidence remains unacceptably high. Thus, vasopressors remain essential in maintaining maternal blood pressure during these procedures.

In this study, 100 women were initially assessed, with 2 excluded. The remaining 98 were randomly assigned to receive a continuous infusion of either norepinephrine or phenylephrine. During the follow-up process, 2 patients from each group were lost, resulting in 47 participants per group for final analysis.

The results showed that norepinephrine was significantly more effective, with a lower incidence of hypotension (14.9% vs. 42.6%). It also provided more stable heart rates with fewer episodes of bradycardia and less need for rescue medications. Both treatments were safe for the babies with comparable Apgar scores.

This study suggests that Norepinephrine infusion at 0.05 mcg/kg/min is more effective than phenylephrine at 0.25 mcg/kg/min in preventing hypotension during low-dose SA in CD, providing better hemodynamic stability and fewer episodes of bradycardia

Study Overview

• Status: Completed
• Conditions: Cesarean Section; Anesthesia; Spinal; Hypotension, Controlled
• Intervention / Treatment: Drug: Norepinephrine; Drug: Phenylephrine

Detailed Description

Upon arrival in the operating room, the parturient was monitored using standard American Society of Anesthesiologists monitors, including electrocardiography, pulse oximetry, and invasive arterial BP measurement. A large peripheral vein was cannulated using an 18-gauge intravenous catheter for the administration of fluids and medications. Baseline BP was determined by averaging three measurements taken 2 minutes apart in the supine position before SA. Low-dose SA was performed with 8 mg of bupivacaine (Marcain) combined with 20 mcg of fentanyl and 100 mcg of morphine (Opiphine). At injection, patients received 15 ml/kg of 0.9% saline IV and group-specific vasopressors:

• P group: Continuous intravenous phenylephrine infusion was administered at 0.25 mcg/kg/min, prepared by diluting 500 mcg in 50 mL of 0.9% sodium chloride.
• N group: Continuous intravenous norepinephrine infusion was administered at 0.05 mcg/kg/min, prepared by diluting 100 mcg in 50 mL of 0.9% sodium chloride.

Following SA, patients were placed in a 15° left lateral tilt and administered 4 mg of ondansetron and 4 mg of dexamethasone intravenously. The sensory block was assessed at 10 minutes; a block at or above the xiphoid was considered effective. After placental delivery, uterotonics were administered as prescribed by the obstetrician. Vasopressor infusion was stopped 5 minutes after delivery.

BP and heart rate (HR) were recorded every 2 minutes during the first 30 minutes after SA, then every 5 minutes until the end of surgery. Neonatal HR was monitored continuously, and Apgar scores were assessed at 1 and 5 minutes by a neonatologist.

Management of Hemodynamic Events and Bradycardia Hypotension was defined as systolic blood pressure (SBP) < 90 mmHg or a drop of more than 20% from baseline. Management involved increasing the vasopressor infusion rate by 20%, followed by administration of phenylephrine 50 mcg intravenously if the HR was ≥ 75 bpm, or ephedrine 6 mg IV if HR was < 75 bpm. The infusion rate was returned to baseline once SBP recovered to the target range (80-120% of baseline).

Severe hypotension (SBP < 60% of baseline) was treated using the same approach but with a higher dose of rescue vasopressors: phenylephrine 100 mcg IV or ephedrine 12 mg IV, depending on HR.

In cases of hypertension (SBP > 120% of baseline), the vasopressor infusion was reduced by 50%. If the SBP exceeded 130%, the infusion was temporarily stopped and reinitiated at 50% of the original dose once the SBP returned to the target range.

Bradycardia was defined as a HR of less than 60 bpm. Management of bradycardia was based on the patient's hemodynamic status. If bradycardia occurred without hypotension, the vasopressor infusion was temporarily discontinued, and if the HR recovered to ≥ 60 bpm, the infusion was resumed at 50% of the original dose. Persistent bradycardia (>3 minutes) was treated with atropine 0.5 mg IV, up to 3 doses. If bradycardia was associated with hypotension, ephedrine 6 mg IV was administered.

• Study Type: Interventional
• Enrollment (Actual): 100
• Phase: Phase 4

Contacts and Locations

Study Locations

• Vietnam
  • Ho Chi Minh
    • Ho Chi Minh City, Ho Chi Minh, Vietnam, 700000
      • Tam Anh TP. Ho Chi Minh General Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Parturients aged ≥18 years
• Classified as American Society of Anesthesiologists physical status II
• Term singleton pregnancies
• Scheduled for elective CD under SA

Exclusion Criteria:

• Refusal to participate.
• Fetal anomalies or suspected fetal compromise
• Preeclampsia or eclampsia
• Conversion to general anesthesia or use of labor analgesia
• Contraindication to SA
• Preexisting cardiovascular or cerebrovascular disease; chronic hypertension
• Baseline bradycardia
• Current use of cardiovascular or antihypertensive medications
• Body mass index more than 40 kg/m²
• Body weight less than 50 kg or more than 100 kg

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Norepinephrine; Continuous intravenous norepinephrine infusion was administered at 0.05 mcg/kg/min, prepared by diluting 100 mcg in 50 mL of 0.9% sodium chloride	Drug: Norepinephrine; Continuous intravenous norepinephrine infusion was administered at 0.05 mcg/kg/min, prepared by diluting 100 mcg in 50 mL of 0.9% sodium chloride
Experimental: Phenylephrine; Continuous intravenous phenylephrine infusion was administered at 0.25 mcg/kg/min, prepared by diluting 500 mcg in 50 mL of 0.9% sodium chloride	Drug: Phenylephrine; Continuous intravenous phenylephrine infusion was administered at 0.25 mcg/kg/min, prepared by diluting 500 mcg in 50 mL of 0.9% sodium chloride

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Hypotension	Hypotension was defined as systolic blood pressure (SBP) < 90 mmHg or a drop of more than 20% from baseline.	From the completion of spinal injection until 5 minutes after the neonate is delivered.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Bradycardia	Bradycardia was defined as a HR of less than 60 beat per minute.	From the completion of spinal injection until 5 minutes after the neonate is delivered.
Hypertension	Hypertension was defined as systolic blood pressure (SBP) > 120% of baseline.	From the completion of spinal injection until 5 minutes after the neonate is delivered
Severe hypotension	Severe hypotension was defined as systolic blood pressure (SBP) < 60% of baseline	From the completion of spinal injection until 5 minutes after the neonate is delivered
Requirement for rescue vasopressors (phenylephrine or ephedrine) and atropine	Requirement for rescue vasopressors (phenylephrine or ephedrine) and atropine during vasopressor administration	From the completion of spinal injection until 5 minutes after the neonate is delivered
Nausea and vomiting	Maternal intraoperative nausea or vomiting during vasopressor administration	From the completion of spinal injection until 5 minutes after the neonate is delivered
Neonatal Apgar Score	The Apgar score is a standardized clinical assessment tool used to evaluate the physical condition of newborns immediately after birth. The title "Apgar" stands for Appearance, Pulse, Grimace, Activity, and Respiration. In this study, the assessment is performed by a qualified neonatologist. Each of the five criteria is scored from 0 to 2, resulting in a total score ranging from 0 to 10. Minimum Value: 0. Maximum Value: 10 Interpretation: Scores 0-3: Critically low; indicates the newborn requires immediate life-saving resuscitation. Scores 4-6: Fairly low; indicates the newborn may require some resuscitative measures or close monitoring. Scores 7-10: Normal; indicates the newborn is in good to excellent condition. Direction: Higher scores represent a better clinical outcome for the neonate.	At 1 and 5 minutes after birth

Collaborators and Investigators

• Sponsor: Tam Anh Research Institute

Publications and helpful links

General Publications

• 1. Afolabi BB, Lesi FEA. Regional versus general anaesthesia for caesarean section. Cochrane Database of Systematic Reviews. 2012(10). doi: 10.1002/14651858.CD004350.pub3. PubMed PMID: CD004350. 2. Vallejo MC, Attaallah AF, Elzamzamy OM, Cifarelli DT, Phelps AL, Hobbs GR, et al. An open-label randomized controlled clinical trial for comparison of continuous phenylephrine versus norepinephrine infusion in prevention of spinal hypotension during cesarean delivery. International journal of obstetric anesthesia. 2017;29:18-25. Epub 2016/10/11. doi: 10.1016/j.ijoa.2016.08.005. PubMed PMID: 27720613. 3. Klöhr S, Roth R, Hofmann T, Rossaint R, Heesen M. Definitions of hypotension after spinal anaesthesia for caesarean section: literature search and application to parturients. Acta anaesthesiologica Scandinavica. 2010;54(8):909-21. Epub 2010/05/12. doi: 10.1111/j.1399-6576.2010.02239.x. PubMed PMID: 20455872. 4. Herbosa GAB, Tho NN, Gapay AA, Lorsomradee S, Thang CQ. Consensus on the Southeast Asian management of hypotension using vasopressors and adjunct modalities during cesarean section under spinal anesthesia. Journal of Anesthesia, Analgesia and Critical Care. 2022;2(1):56. doi: 10.1186/s44158-022-00084-1. 5. Kinsella SM, Carvalho B, Dyer RA, Fernando R, McDonnell N, Mercier FJ, et al. International consensus statement on the management of hypotension with vasopressors during caesarean section under spinal anaesthesia. Anaesthesia. 2018;73(1):71-92. Epub 2017/11/02. doi: 10.1111/anae.14080. PubMed PMID: 29090733. 6. Allen TK, George RB, White WD, Muir HA, Habib AS. A double-blind, placebo-controlled trial of four fixed rate infusion regimens of phenylephrine for hemodynamic support during spinal anesthesia for cesarean delivery. Anesthesia and analgesia. 2010;111(5):1221-9. Epub 2010/05/25. doi: 10.1213/ANE.0b013e3181e1db21. PubMed PMID: 20495139. 7. Habib AS. A Review of the Impact of Phenylephrine Administration on Maternal Hemodynamics and Maternal and Neonatal Outc

Helpful Links

• Related Info

Study record dates

Study Major Dates

• Study Start (Actual): June 6, 2024
• Primary Completion (Actual): October 4, 2025
• Study Completion (Actual): October 4, 2025

Study Registration Dates

• First Submitted: December 24, 2025
• First Submitted That Met QC Criteria: December 24, 2025
• First Posted (Actual): January 8, 2026

Study Record Updates

• Last Update Posted (Actual): January 21, 2026
• Last Update Submitted That Met QC Criteria: January 19, 2026
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Hypotension; Norepinephrine; Cesarean delivery; Phenylephrine; Spinal anaesthesia
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Hypotension; Organic Chemicals; Hydrocarbons; Hydrocarbons, Cyclic; Hydrocarbons, Aromatic; Amines; Catechols; Phenols; Benzene Derivatives; Alcohols; Amino Alcohols; Ethanolamines; Biogenic Monoamines; Biogenic Amines; Catecholamines; Norepinephrine; Phenylephrine
• Other Study ID Numbers: TA2.24.03

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No