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NCT Number: NCT07824713

ED50/ED90 of Phenylephrine Infusion for Preventing Spinal Anesthesia-Induced Hypotension: Supine vs Left-Tilt 15°

The purpose of this study is to determine the 50% and 90% effective doses (ED50 and ED90) of prophylactic phenylephrine infusion for preventing spinal anesthesia-induced hypotension during elective cesarean delivery, in the supine position and in the left-lateral-tilt 15° position, respectively. Two hundred parturients with singleton term pregnancies will be randomized 1:1 to the supine group or the left-tilt 15° group, and within each position 1:1:1:1 to one of four fixed phenylephrine infusion rates (0.2, 0.4, 0.6, or 0.8 μg/kg/min; 25 per group), with the rate allocation masked by concentration blinding (identical pump rate, different solution concentrations). Spinal anesthesia consists of hyperbaric bupivacaine 12 mg plus morphine 0.15 mg. The primary outcome is the incidence of hypotension (systolic blood pressure < 80% of baseline or < 90 mmHg) from completion of the intrathecal injection to delivery. ED50 and ED90 will be estimated by probit regression within each position.

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Key information

Conditions

Hypotension After Spinal Anesthesia Cardiovascular Diseases Hypotension Vascular Diseases

Age range

18 year and older

Sex eligibility

Female

Study type

Interventional

Phase

Phase 4

Primary location

Department of Anesthesiology，Xuzhou HeJia Hospital, Xuzhou, Jiangsu, China

Xuzhou, Jiangsu, 221000, China

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Singleton term pregnancy scheduled for elective cesarean delivery
  • Height 150-180 cm
  • ASA physical status II-III
  • Body mass index < 35 kg/m2

Exclusion criteria

  • Transverse lie or suspected macrosomia
  • Uterine abnormalities (e.g., large uterine fibroids, bicornuate uterus)
  • Polyhydramnios
  • Ruptured membranes or oligohydramnios
  • Fetal growth restriction
  • Gestational or pregestational hypertension, diabetes mellitus, or preeclampsia
  • Diseases associated with autonomic neuropathy (e.g., diabetes mellitus > 10 years) or renal failure
  • Contraindications to spinal anesthesia
  • Refusal to provide written informed consent-

Treatment and study plan

Phenylephrine hydrochloride infusion

Drug

Prophylactic fixed-rate IV infusion (pump rate 0.6 mL/kg/h, concentration-blinded), from completion of spinal anesthesia until delivery

Primary outcomes

  1. hypotension incidence of hypotension from completion of intrathecal injection to delivery of the infant

    Time frame: From completion of spinal anesthesia to fetal delivery

    Hypotension defined as systolic blood pressure < 80% of baseline (measured in the assigned study position) or < 90 mmHg

Secondary outcomes

  1. Umbilical artery and umbilical vein blood gas values

    Time frame: At delivery

    Umbilical artery and umbilical vein blood gas values (pH, PCO2, PO2, base excess, lactate)

  2. Apgar scores at 1 and 5 minutes after delivery

    Time frame: From fetal delivery to 5 minutes after delivery

  3. Time to first rescue vasopressor

    Time frame: From completion of intrathecal injection to delivery

  4. Serial systolic blood pressure values within 12 minutes after intrathecal injection

    Time frame: From completion of spinal anesthesia to 12 minutes after completion of spinal anesthesia

  5. Incidence of hypertension before delivery

    Time frame: From completion of intrathecal injection to delivery

    Incidence of hypertension (systolic blood pressure ≥ 120% of baseline) before delivery

Study contacts

Contact information is provided by the study sponsor or research team.

Feng Feng, Dr.

CONTACT

[email protected]

13601083503

Sponsors and collaborators

Lead sponsor

Peking University People's Hospital

Other

Collaborators

  • XuZhouHeJia hospital

Registry information

Official study title

Determination of the ED50 and ED90 of Prophylactic Phenylephrine Infusion for the Prevention of Spinal Anesthesia-Induced Hypotension During Elective Cesarean Delivery in the Supine and Left-Lateral-Tilt 15° Positions: A Randomized, Concentration-Blinded, Parallel-Group Dose-Response Study

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Sep 17, 2026
Registry last updated
Sep 17, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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