LCN2 and acute kidney injury: As depicted in Figure 7A, the co-cited references were grouped into 16 primary cluster labels: oxygen delivery, venous congestion, RIFLE, children, biomarker, timing, hydroxyethyl starch, statins, machine learning, cardiac surgery, neutrophil gelatinase-associated lipocalin, remote ischemic preconditioning, hypotension, pediatric, aortic stenosis, postoperative AKI and levosimendan.