Association of intraoperative hypotension and cumulative norepinephrine dose with postoperative acute kidney injury in patients having noncardiac surgery: a retrospective cohort analysis

Intraoperative hypotension is associated with acute kidney injury (AKI). Clinicians thus frequently use vasopressors, such as norepinephrine, to maintain blood pressure. However, vasopressors themselves might promote AKI. We sought to determine whether both intraoperative hypotension and cumulative intraoperative norepinephrine dose are independently associated with postoperative AKI in patients undergoing noncardiac surgery. This was a retrospective cohort analysis of 38 338 adult male and female patients who had noncardiac surgery. The primary outcome was AKI within the first 7 postoperative days. We performed adjusted multivariable logistic regression analysis to determine whether intraoperative hypotension (quantified as area under a mean arterial pressure [MAP] of 65 mm Hg) and cumulative intraoperative norepinephrine dose were independently associated with AKI. The median (25th percentile, 75th percentile) area under a MAP of 65 mm Hg was 0.09 (0.02, 0.22) mm Hg∗day in patients with AKI and 0.05 (0.01, 0.14) mm Hg∗day in patients without AKI (P<0.001). The cumulative intraoperative norepinephrine dose was 1.92 (0.00, 13.09) μg kg-1 in patients with AKI and 0.00 (0.00, 0.00) μg kg-1 in patients without AKI (P<0.001). Both the area under a MAP of 65 mm Hg (odds ratio 1.55 [95% confidence interval 1.17-2.02] per mm Hg∗day; P=0.002) and the cumulative intraoperative norepinephrine dose (odds ratio 1.02 [95% confidence interval 1.01-1.02] per μg kg-1; P<0.001) were independently associated with AKI. Both intraoperative hypotension and cumulative intraoperative norepinephrine dose were independently associated with postoperative AKI in patients undergoing noncardiac surgery. Pending results of trials testing whether these relationships are causal, it seems prudent to avoid both profound hypotension and high norepinephrine doses in adults undergoing noncardiac surgery.