CHI3L1 and acute kidney injury: To confirm the association between AKI and elevated CHI3L1 independent of iNO exposure, a subgroup analysis was performed using patients in the placebo arm of the trial: AKI grade 1, 2 and 3 was associated with CHI3L1 concentrations 0.94, 1.31, and 2.41-fold higher than patients without AKI, over the course of the first 3 days of hospitalization (p = 0.017).