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Prophylactic Norepinephrine and Phenylephrine Boluses to Prevent Postspinal Anesthesia Hypotension During Cesarean
Lei Guo1, Xiangzhao Xu2, Rui Qin1
1Department of Anesthesiology and Perioperative Medicine, General Hospital of Ningxia Medical University, Yinchuan, People's Republic of China.
Drug Design, Development and Therapy
|May 30, 2023
Summary
Prophylactic norepinephrine (8 μg) and phenylephrine (90 μg) effectively prevent hypotension during cesarean section anesthesia. Norepinephrine showed a lower incidence of bradycardia compared to phenylephrine.
Area of Science:
- Obstetrics
- Anesthesiology
- Pharmacology
Background:
- Norepinephrine and phenylephrine are common vasopressors in obstetric anesthesia.
- Postspinal anesthesia hypotension is a significant concern during cesarean sections.
Purpose of the Study:
- To determine the effective dose 90 (ED90) and potency ratio of prophylactic norepinephrine and phenylephrine boluses.
- To compare the efficacy of these agents in preventing hypotension during cesarean section.
Main Methods:
- Eighty patients undergoing elective cesarean section were randomized to receive prophylactic norepinephrine or phenylephrine boluses.
- An up-and-down sequential allocation method was used to determine ED90 based on preventing a systolic blood pressure drop below 80% of baseline.
- Outcomes included ED90, potency ratio, hypotension incidence, and adverse events.
Main Results:
- The ED90 for norepinephrine was 8.0 μg (95% CI 7.1-11.0 μg) and for phenylephrine was 90.9 μg (95% CI 82.0-123.9 μg).
- The relative potency ratio was 11.4:1 (norepinephrine:phenylephrine).
- Bradycardia occurred less frequently with norepinephrine (2.5% vs. 20%, P=0.034).
Conclusions:
- Prophylactic 8-μg norepinephrine or 90-μg phenylephrine boluses effectively prevent postspinal anesthesia hypotension in cesarean delivery.
- Norepinephrine is significantly more potent than phenylephrine for this indication and is associated with less bradycardia.
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