Determination of the 90% Effective Dose of the Initial Bolus of Norepinephrine Followed by a Continuous Infusion to Prevent Hypotension in Elective Cesarean Delivery: A Randomized, Double-Blind, Up–Down Study
Authors' conclusion
An initial norepinephrine bolus of approximately 0.16 µg kg-1, followed by an infusion, appears effective in preventing postspinal hypotension during elective cesarean delivery and is associated with a low incidence of adverse events.
Study context
- Population
- Full-term women (ASA II–III, 18–40 years, singleton pregnancies) undergoing elective cesarean delivery under spinal anesthesiaone excluded (protocol violation)
- Participants
- 61 women
- Comparison
- Norepinephrine prophylactic bolus doses (starting 0.13 or 0.15 µg kg-1) followed by infusion at 0.05 µg kg-1 min-1
- Primary endpoint
- Systolic hypotension (SBP <80% of baseline); ED90 of norepinephrine bolus
- Follow-up
- Within 10 minutes of spinal anesthesia
Methodological detailsdouble-blind, up-and-down k-in-a-row dose-finding
- Double-blind
- Up-and-down k-in-a-row dose-finding
Primary result
As reported in the abstract
Effective dosing (prevention of hypotension) and ED90
- Trend in effective rates across doses (chi-square trend)
- P = 0.019
- Dose-dependency
- P = 0.034
- Effect of randomized sequence
- P = 1.00
- Overall effective dosing, n = 54
- 90.0% (95% CI, 79.9-95.3)
- ED90, Firth logistic regression
- 0.157 μg kg-1 (95% CI, 0.142-0.172)
- ED90, centered isotonic regression (sensitivity analysis)
- 0.157 μg kg-1 (95% CI, 0.130-0.173)
Safety
Adverse events
- Hypotension
- 6 (12.2%)
- Transient hypertension
- 10 (8.2%)
- Nausea
- 6 (10%)
- Vomiting
- 2 (3.3%)
- Severe neonatal hypoglycemia, without clinical manifestations
- 1 (1.7%)
Original publication
Determination of the 90% Effective Dose of the Initial Bolus of Norepinephrine Followed by a Continuous Infusion to Prevent Hypotension in Elective Cesarean Delivery: A Randomized, Double-Blind, Up–Down Study. Anesth Analg. Published 10 August 2026. doi:10.
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