Norepinephrine infusion for prophylaxis against spinal-induced hypotension in elderly patients undergoing hip surgery: a randomized controlled comparison of two doses.

BACKGROUND: We aimed to compare the hemodynamic response to two norepinephrine infusion rates for prophylaxis against post-spinal hypotension in elderly population undergoing hip surgery. METHODS: This randomized non-inferiority clinical trial included elderly patients scheduled for hip surgery under spinal anesthesia. Patients received norepinephrine infusion at a rate of 0.1 mcg/kg/min (0.1-mcg group) or 0.07 mcg/kg/min (0.07-mcg group) after spinal anesthesia. Intraoperative mean arterial pressure (MAP) and heart rate were recorded every 2 min for 46 min after spinal anesthesia. The primary outcome was the noninferiority comparison between the two groups regarding the average MAP readings. Non-inferiority was declared if the average post-spinal MAP in the 0.07-mcg group was within 8 mmHg of the 0.1-mcg group. Secondary outcomes were incidence of post-spinal hypotension (MAP < 70% of baseline or < 65 mmHg), bradycardia, and hypertension. The secondary outcomes were assessed for superiority. RESULTS: Eighty-four patients were analyzed. The average intraoperative MAP was 87.9 ± 9.5 mmHg in the 0.1-mcg group and 84.5 ± 8.5 mmHg in the 0.07-mcg group, with a mean difference of -3.5 mmHg (95% confidence interval: -7.4 to 0.4 mmHg) and the lower bound of the 95% confidence interval did not cross the prespecified non-inferiority margin. The incidence of hypotension, hypertension, and bradycardia was comparable between the two groups. CONCLUSION: In elderly patients undergoing hip surgery under spinal anesthesia, a norepinephrine infusion rate of 0.07 mcg/kg/min was not inferior to 0.1 mcg/kg/min in maintaining post-spinal MAP. Both infusion rates had comparable profile regarding adverse events, namely reactive hypertension and bradycardia. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT07077265. URL: https://www. CLINICALTRIALS: gov/study/NCT07077265?term=NCT07077265&rank=1 .