Comparison of Continuous Norepinephrine and Phenylephrine Infusion for Preventing Hypotension During Low-Dose Spinal Anesthesia in Cesarean Delivery: A Randomized Controlled Trial
试验速览
- 阶段
- 4 期
- 状态
- 已完成
- 发起方
- 入组人数
- 100
- 试验地点
- 1
- 主要终点
- Hypotension
研究概览
简要总结
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
详细描述
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).
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Prevention
- 盲法
- Single (Participant)
盲法说明
The randomization sequence was concealed in sequentially numbered, opaque, sealed envelopes. Each envelope contained the specific intervention protocol for the assigned group. The Principal Investigator generated the allocation sequence and prepared the envelopes prior to the study. To ensure concealment, the recruiting investigator opened the next envelope in the sequence only after the participant was enrolled, thereby determining the group assignment.
This was a single-blind study; only the participants were blinded to the group allocation. Due to the nature of vasopressor administration and the need for real-time hemodynamic management, the investigators and the anesthesiology team were aware of the assigned intervention to ensure patient safety and proper medication delivery
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- Female
- 接受健康志愿者
- 是
入选标准
- •Parturients aged ≥18 years
- •Classified as American Society of Anesthesiologists physical status II
- •Term singleton pregnancies
- •Scheduled for elective CD under SA
排除标准
- •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
研究组 & 干预措施
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
干预措施: Norepinephrine (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
干预措施: Phenylephrine (Drug)
结局指标
主要结局
Hypotension
时间窗: From the completion of spinal injection until 5 minutes after the neonate is delivered.
Hypotension was defined as systolic blood pressure (SBP) \< 90 mmHg or a drop of more than 20% from baseline.
次要结局
- Bradycardia(From the completion of spinal injection until 5 minutes after the neonate is delivered.)
- Hypertension(From the completion of spinal injection until 5 minutes after the neonate is delivered)
- Severe hypotension(From the completion of spinal injection until 5 minutes after the neonate is delivered)
- Requirement for rescue vasopressors (phenylephrine or ephedrine) and atropine(From the completion of spinal injection until 5 minutes after the neonate is delivered)
- Nausea and vomiting(From the completion of spinal injection until 5 minutes after the neonate is delivered)
- Neonatal Apgar Score(At 1 and 5 minutes after birth)