Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Epidemiology and Biostatistics

Supervisor

Dubois, Luc

2nd Supervisor

Garg, Amit X

Co-Supervisor

Abstract

Strategies for preventing acute kidney injury (AKI) in patients undergoing abdominal aortic aneurysm (AAA) repair were explored in a secondary data analysis of 601 patients from a randomized controlled trial (RCT). Bivariate analyses identified an association between intraoperative hypotension and postoperative AKI and suggested IV fluids as the best treatment option over inotropes/vasopressors which increased the odds of AKI (ORcrude=2.5 95%CI 1.2-5.0), however, our multivariable analysis was non-significant (ORadjusted=1.7 95%CI 0.8-3.7). Further analysis found angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker use within 24 hours prior to repair were not associated with postoperative AKI (ORadjusted=1.3 95%CI 0.8-2.2). Our systematic review of RCT literature failed to identify any definitive evidence for effective preventive strategies, andour meta-analysis of 6 RCTs analyzing remote-ischemic preconditioning showed no statistically significant difference (OR 1.2 95%CI 0.4-3.9). Large, multi-centre RCTs are needed to identify preventive strategies for AKI after AAA repair.

Summary for Lay Audience

An abdominal aortic aneurysm (AAA) is the ballooning of the aorta in the abdomen caused by a weakening in the walls of the vessel. Aneurysms can occur in different locations along the aorta and can negatively affect the supply of blood to the kidneys. The repair of an AAA can cause stress to the kidneys due to the procedure and/or different drugs resulting in acute kidney injury (AKI), a significant complication associated with AAA repair. AKI is defined as an abrupt decline in kidney function. This thesis explores potential strategies for preventing AKI in patients undergoing AAA repair. We explored this in a secondary data analysis of 601 patients from a randomized controlled trial (RCT). Statistical analyses identified an association between low blood pressure during surgery and postoperative AKI. Analyses of the treatments of the low blood pressure during surgery suggested IV fluids as the possible best treatment option over inotropes/vasopressors which increased the odds of patients developing AKI after surgery, however further analysis was non-significant, so the evidence is unclear. Drugs to treat high blood pressure have been thought to affect the results of patients undergoing AAA repair and there are conflicting opinions about whether they should be stopped before surgery or not. Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers are drugs used to treat high blood pressure and if taken close to surgery, they may increase the risk of low blood pressure during surgery which is associated with AKI. Our analysis found angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers taken within 24 hours prior to repair were not associated with postoperative AKI. We conducted a systematic review and meta-analysis of RCT literature, but we did not identify any conclusive evidence for effective preventive strategies. Future research needs to be conducted to identify preventive strategies for AKI after AAA repair using randomized trials.

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