Individualized intraoperative blood pressure control with norepinephrine reduces kidney injury biomarkers but not creatinine-defined acute kidney injury in older patients with hypertension undergoing major abdominal surgery: a single-center randomized controlled trial.

[BACKGROUND] This randomized trial aimed to determine whether achievement of individualized blood pressure targets through norepinephrine administration can mitigate acute kidney injury (AKI) and reduce urine concentration, which serves as a surrogate marker for fluid retention, in older patients undergoing major abdominal surgery.

[METHODS] This study included 166 patients aged 55-80 years who were scheduled to undergo gastrectomy or colorectal cancer resection. They were randomly assigned to the individualized care group, in which systolic blood pressure or mean arterial pressure was maintained within ± 10% and ± 20% of baseline, respectively, using norepinephrine; or to the usual care group, in which mean arterial pressure was maintained at ≥ 65 mmHg without individualized titration. Individuals in both groups underwent continuous arterial monitoring and goal-directed fluid therapy. AKI was diagnosed based on the Kidney Disease: Improving Global Outcomes criteria. Further, renal injury was assessed based on serum neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) levels. Urine concentration scores were calculated from the urine parameters.

[RESULTS] AKI occurred in 13.5% and 14.3% of patients in the individualized and usual care groups, respectively. Patients in the usual care group experienced significant intraoperative fluctuations in mean arterial pressure. Norepinephrine was administered to 80.9% and 17.1% of patients in the individualized and usual care groups, respectively. Compared with the usual care group, the individualized care group demonstrated reduced NGAL levels and KIM-1 levels at the end of surgery and on postoperative day 2, and lower urine concentration scores at the end of surgery and on postoperative day 1.

[CONCLUSION] Individualized blood pressure management using norepinephrine mitigated kidney damage, as indicated by elevated biomarkers, and decreased urine concentration, a surrogate indicator of fluid retention. However, it did not significantly reduce the incidence of AKI.

[TRIAL REGISTRATION] This trial was registered in the Chinese Clinical Trial Registry (ChiCTR2100049843) on August 10, 2021 ( https://www.chictr.org.cn/ ).