Impact of Intraoperative Hypotension During Cardiopulmonary Bypass on Acute Kidney Injury After Coronary Artery Bypass Grafting

Abstract

Objective: The aim of this study was to investigate whether acute kidney injury (AKI) after coronary artery bypass grafting can be attributed to intraoperative hypotension during cardiopulmonary bypass (IOH-CPB).

Design: Retrospective analysis.

Setting: Tertiary-care hospital.

Participants: Patients undergoing on-pump coronary artery bypass grafting from June 2011 to January 2014.

Interventions: None.

Measurements and main results: IOH-CPB was defined as blood pressure below several absolute and relative mean arterial pressure (MAP) thresholds and as the area under the curve for absolute MAP thresholds. AKI was defined as an absolute increase in serum creatinine of≥26 µmol/L within 48 hours or an increase to 150% or more within 7 days of surgery. Poisson regression with robust standard errors both before and after adjustment for confounders was used. Of the 1,891 patients included, 386 (20%) developed AKI. In univariable analysis, all IOH-CPB thresholds defined as a MAP of 50 mmHg or less and as a decrease in MAP of 60% from baseline were associated with a 1.07-to-1.11 times increased risk of AKI per 10 minutes of IOH-CPB (p<0.01). After adjustment for potential confounders, IOH-CPB, irrespective of the definition chosen, was not associated with an increased risk of AKI.

Conclusions: In the authors' study population, univariable analysis showed an association of IOH-CPB with AKI in patients undergoing isolated CABG, but this relationship disappeared after correction for well-known risk factors for AKI.

Keywords: acute kidney injury; coronary artery bypass grafting; hypotension; outcome.