1 Center for Critical Care Nephrology, Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA. Electronic address: kellumja@upmc.edu.
2 Division of Nephrology and Hypertension, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
3 Intensive Care Unit, Royal Surrey Hospital NHS Foundation Trust, Guildford, United Kingdom & Department of Clinical & Experimental Medicine, University of Surrey, Guildford, UK.