LCN2 and acute respiratory distress syndrome: Pediatric intensivists must define the most suitable outcomes to test the primary or secondary hypotheses generated in their research, possibly based on physiological (e.g., heart rate variability, microcirculatory flow), molecular [e.g., glycoprotein KL-6 for ARDS (55), neutrophil gelatinase-associated lipocalin (NGAL) for kidney injury (51), shed CD163 for organ dysfunction (56)], or imaging biomarkers [e.g., apparent diffusion coefficient (ADC) using diffusion tensor imaging (57), oxygen extraction fraction (OEF) using positron emission tomography (58)].