Predictable Norepinephrine Dosing Improves Personalized BP Management During Anaesthesia: Study

Could a simple math equation guide safer, more effective vasopressor use during your next case? For decades, anaesthetists have titrated norepinephrine by feel, balancing the fine line between hypotension and hypertension. But what if you could proactively estimate the right dose before blood pressure starts to drop—especially under general anaesthesia?

Study Design: A Closer Look at Norepinephrine and Blood Pressure

This observational study, published in the Eur J Anaesthesiol, enrolled 36 healthy volunteers aged 18–70. Each participant first received stepwise norepinephrine infusions while awake, then repeated the protocol under general anaesthesia (using propofol and remifentanil) and simulated surgical stimulation. Researchers continuously monitored mean arterial pressure (MAP) and other haemodynamic parameters, comparing dose–response relationships in both states.

Key Findings: Dose–Response Is Linear—and Steeper Under Anaesthesia

The relationship between norepinephrine dose and MAP was linear both while awake and under general anaesthesia. Notably, the slope of the dose–response curve was significantly steeper during anaesthesia, meaning blood pressure was more sensitive to each increment of norepinephrine when patients were under propofol/remifentanil. This finding makes intuitive sense: anaesthetics reduce vascular tone, making the vasculature more responsive to catecholamines.

Practical Implication: An Equation for Norepinephrine Dosing

For the first time, the researchers derived a simple formula to estimate norepinephrine requirements during anaesthesia:

(Target MAP−54)/222=mg⋅kg−1⋅min−1

For example, to maintain a MAP of 65 mmHg, you’d need approximately 0.05 mg/kg/min of norepinephrine.

Broader Haemodynamic Effects: More Than Just Blood Pressure

Beyond MAP, norepinephrine also positively influenced cardiac contractility (measured as arterial dP/dtmax) and restored cardiac output and stroke volume index to baseline with relatively modest doses under anaesthesia. However, heart rate and venous filling pressures were less affected, indicating selectivity in norepinephrine’s haemodynamic impact.

Limitations and Real-World Use

While the study provides a valuable baseline for healthy adults, clinical titration remains essential. Individual variability, patient comorbidities, surgical blood loss, and anaesthetic regimens can all impact vasopressor needs. Still, the linear model offers a more proactive, evidence-based approach than simple “trial and error.”

Conclusion

This research demonstrates a predictable, linear relationship between norepinephrine dose and MAP during general anaesthesia, enabling clinicians to estimate starting doses more accurately. While not a substitute for clinical judgement, this approach moves us closer to truly personalized, data-driven haemodynamic management in the OR.

Key points

The Eur J Anaesthesiol study found a linear, predictable relationship between norepinephrine dose and mean arterial pressure in healthy volunteers.

The dose–response curve was significantly steeper under general anaesthesia, meaning patients are more sensitive to vasopressor titration when anesthetized.

A simple equation enables clinicians to estimate starting norepinephrine infusion rates for target blood pressures during anaesthesia.

Norepinephrine also improved cardiac contractility and output at modest doses, with little effect on heart rate or venous pressures.

While useful for proactive dosing, clinical observation and titration remain essential due to individual patient variability.

Citation:

de Keijzer IN, van den Berg JP, Massari D, Absalom AR, Bosch DJ, van Faassen M, Scheeren TWL, Struys MMRF, Colin PJ, Vos JJ. The dose-response relationship between norepinephrine dose and mean arterial pressure with and without general anaesthesia: A study in healthy volunteers. Eur J Anaesthesiol. 2026;43:506–516. DOI:10.1097/EJA.0000000000002312