von T, Meersch M, Romagnoli S, Ostermann M, Ripollés J, Schneider AG, Vandenberghe W, Monard C, De Rosa S, Cattin L, Rahmel T, Adamzik M, Parise D, Candela A, Haaker JG, Göbel U, Bernard A, Lumlertgul N, Fernández P, Romero I, Suarez A, Larmann J, Villa G, Spadaro S, Wulf H, Arndt C, Putensen C, García R, Brandenburger T, Siniscalchi A, Ellerkmann R, Espeter F, Porschen C, Sadjadi M, Saadat K, Weiss R, Gerss J, Kellum J, Zarbock A, BigpAK I. Biomarker-guided intervention to prevent acute kidney injury after major surgery (BigpAK-2 trial): study protocol for an international, prospective, randomised controlled multicentre trial