As part of standard operative technique patient's bladders are catheterised prior to the start of surgery and the first 100mls urine voided will be collected as the baseline sample. Venous blood will be taken at cannulation with serum spun and frozen for later analysis of NGAL (and any emergent biomarkers of AKI of interest). Finger prick blood sampling will be performed for baseline point of care analysis of NGAL/brain natriuretic peptide using the Alere platform.