Prophylactic infusion of norepinephrine enhances hemodynamic stability during propofol induction and early intubation period in elderly patients: a double-blind randomized placebo-controlled trial

Background: The induction of general anesthesia with propofol often results in hypotension, which is primarily attributed to a decrease in the cardiac index (CI) among elderly patients. Norepinephrine (NE) is typically used to manage anesthesia-induced hypotension. We hypothesized that NE attenuates the reduction in CI while preserving blood pressure.Methods: In a randomized, double-blinded trial, 60 elderly patients undergoing elective major abdominal surgery under general anesthesia were randomly allocated to receive infusion of NE (6 µg/ml) (NE group) or saline (control [CT] group) during induction. CI was monitored using the FloTrac/Vigileo system, and the primary outcome was the change in CI (△CI) (△Value = value measured at the study time point–baseline value) at 10 min post-intubation (T10). Additionally, changes in systemic vascular resistance index (△SVRI) and mean arterial pressure (△MAP) were also evaluated for comparison.Results: In the NE group, the CI decreased from 3.9 to 2.9 L·min–1/m–2 at 10 min post-intubation (T10), whereas in the CT group, it declined from 3.7 to 2.6 L·min–1/m–2. After adjusting for propofol dosage per weight, the decreases in △CI (β = 0.63, 95% confidence interval [CI] 0.18 to 1.07; P = 0.006) and △MAP (β = 11.99, 95% CI 2.05 to 21.94; P = 0.018) at T10 were significantly less in the NE group compared to the CT group, whereas △SVRI did not show a significant difference between the two groups. From induction until 10 min post-intubation, the reductions in △CI, △MAP and stroke volume (△SV) were attenuated, and stroke volume variation was lower, while △SVRI and pulse rate (△PR) remained comparable between the NE and CT groups.Conclusions: Prophylactic infusion of NE effectively attenuated the decrease in △CI during propofol-induced anesthesia in elderly patients while maintaining MAP.