Background Perioperative acute kidney injury is common. However, it is unclear whether this merely represents a transient increase in creatinine or has prognostic value. Therefore, the long-term clinical importance of mild postoperative acute kidney injury remains unclear. This study assessed whether adults who do and do not experience mild kidney injury after noncardiac surgery are at similar risk for long-term renal injury. Methods This study is a retrospective cohort analysis of adults having noncardiac surgery at the Cleveland Clinic who had preoperative, postoperative, and long-term (1 to 2 yr after surgery) plasma creatinine measurements. The exposure (postoperative kidney injury) and outcome (long-term renal injury) were defined and staged according to the Kidney Disease: Improving Global Outcomes (KDIGO) initiative criteria. The primary analysis was for lack of association between postoperative kidney injury (stage I vs. no injury) and long-term renal injury. Results Among 15,621 patients analyzed, 3% had postoperative stage I kidney injury. Long-term renal outcomes were not similar in patients with and without postoperative stage I injury. Specifically, about 26% of patients with stage I postoperative kidney injury still had mild injury 1 to 2 yr later, and 11% had even more severe injury. A full third (37%) of patients with stage I kidney injury therefore had renal injury 1 to 2 yr after surgery. Patients with postoperative stage I injury had an estimated 2.4 times higher odds of having long-term renal dysfunction (KDIGO stage I, II, or III) compared with patients without postoperative kidney injury (odds ratio [95% CI] of 2.4 [2.0 to 3.0]) after adjustment for potential confounding factors. Conclusions In adults recovering from noncardiac surgery, even small postoperative increases in plasma creatinine, corresponding to stage I kidney injury, are associated with renal dysfunction 1 to 2 yr after surgery. Even mild postoperative renal injury should therefore be considered a clinically important perioperative outcome. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

I NTRAARTERIAL pressure monitoring is routine for patients having cardiac surgery; however, the ideal site for arterial cannulation that best reflects central aortic pressure while minimizing line-associated complications is unclear. Radial arterial cannulation often is preferred because collateral circulation from the ulnar artery to the hand reduces the risk of ischemic injury. 1 However, radial arterial pressure often exaggerates central aortic pressures because of decreased arterial elasticity, amplification of harmonic resonance, and the water hammer effect, which describes a bounding and forceful pulse caused by the propagation of a pressure wave throughout the vasculature. 2 Furthermore, hemodilution or radial artery vasospasm during critical periods of cardiac surgery can cause radial arterial pressure to underestimate central aortic pressure. 3,4 Inaccurate pressure measurements even for brief periods of time may promote inappropriate hemodynamic management and possibly increase postoperative morbidity and mortality. 5 Brachial arterial monitoring, in contrast, closely reflects central aortic pressure even during complex cardiac surgical procedures with prolonged cardiopulmonary bypass support. 3 Brachial arterial pressure may thus better guide patient care and clinical management than radial arterial pressure What We Already Know about This Topic • Brachial arterial catheters better estimate aortic pressure than radial arterial catheters but are used infrequently because of risk of complications in a major artery without collateral flow are potentially serious • The present study evaluated a large cohort of cardiac surgical patients to estimate the incidence of brachial artery catheter complications What This Article Tells Us That Is New • Brachial artery cannulation for hemodynamic monitoring during cardiac surgery rarely causes complications