Association between postoperative acute kidney injury and duration of cardiopulmonary bypass: a meta-analysis

Objective: This meta-analysis examined the association between cardiopulmonary bypass (CPB) time and acute kidney injury (AKI).

Design: Meta-analysis of previously published studies.

Setting: Each single-center study was conducted in a surgical intensive care unit and/or academic or university hospital.

Participants: Adult patients undergoing heart surgery with CPB.

Interventions: A systematic literature review was conducted using PubMed, EMBASE, and Cochrane Library databases and Google Scholar from January 1980 through September 2009. Initial search results were refined to include human subjects, age >18 years, randomized controlled trials, and prospective and retrospective cohort studies, meet the Acute Kidney Injury Network definition of renal failure, and report times on CPB.

Measurements and main results: The length of time on CPB has been implicated as an independent risk factor for development of AKI after CPB (AKI-CPB). The 9 independent studies included in the final meta-analysis had 12,466 patients who underwent CPB. Out of these, 756 patients (6.06%) developed AKI-CPB. In 7 of the 9 studies, the mean CPB times were statistically longer in the AKI-CPB cohort compared with the control group (cohort without AKI). The absolute mean differences in CPB time between the 2 groups were 25.65 minutes with the fixed-effects model and 23.18 minutes with the random-effects model.

Conclusions: Longer CPB times are associated with a higher risk of developing AKI-CPB, which, in turn, has a significant effect on overall mortality as reported by the individual studies.