Reducing acute kidney injury in patients with chronic kidney disease undergoing cardiac surgery.

Abstract

Patients with chronic kidney disease (CKD) are a group with a markedly increased risk of adverse events following cardiac surgery. A particular problem for these patients is the development of post-operative acute kidney injury (AKI), which is associated with a significant increase in morbidity and mortality. Currently, there are no effective therapies proven to modify AKI in patients undergoing cardiac surgery. This thesis has three parts. The first describes an analysis of the Barts Health NHS Trust cardiac surgical dataset. Specifically, outcomes of patients with CKD and AKI were examined. The second describes a randomized control trial that examined the effect of remote ischaemic preconditioning (RIPC) upon AKI and myocardial injury in patients with CKD undergoing coronary artery bypass graft surgery (CABG). The final part describes the development of a panel of AKI biomarkers to allow the accurate prediction of AKI in patients with CKD undergoing CABG. The aims of this thesis were: 1. In our local cardiac surgical cohort, a. To assess the effects of CKD upon outcomes after CABG. b. To asses the prognostic importance of AKI after CABG. 2. To assess the potential for RIPC to reduce AKI and myocardial injury in patients with CKD undergoing CABG. 3. To investigate the diagnostic performance of serum and urine AKI biomarkers in a population of patients with CKD undergoing CABG. Analysis of the Barts Health NHS Trust cardiac surgical dataset confirmed that patients with CKD account for almost one-third of patients undergoing CABG. However, these patients account for a disproportionate two-thirds of all early mortality. CKD was also independently associated with late mortality after CABG. AKI was common in these patients. AKI was associated with late mortality even after accounting for pre-operative comorbidity and surgical complexity. In the randomized control trial, RIPC showed no effect upon the incidence of AKI or myocardial injury in the. 86 patients with CKD recruited. Secondary analysis of serum and urine biomarkers collected found change in serum cystatin C and NGAL as impressive predictors of AKI in patients with CKD. They allowed accurate early prediction of AKI more than 24 hours before diagnosis was possible using serum creatinine.