Is time on cardiopulmonary bypass during cardiac surgery associated with acute kidney injury requiring dialysis?

It is commonly accepted that the longer the time on extracorporeal cardiopulmonary bypass (CPB), the higher is the likelihood of developing acute renal failure requiring dialysis (ARF-D). Nonetheless, previous works elicited conflicting evidence. We investigated the relationship between CPB duration and ARF-D occurrence. Data were extracted from a large observational study. All factors independently associated with ARF-D were detected. Overall, 11,092 case record forms were analyzed. At the univariate analyses, time on CBP was associated with an increase in the ARF-D risk (odds ratio of fifth vs. first quintile of CBP time: 3.84; 95% confidence interval: 2.58-5.7; P < 0.001). However, after adjusting for confounders, the association between time on CBP and ARF-D lost its statistical significance. In this large dataset, CBP time did not predict ARF-D occurrence. These results might suggest that an accurate risk assessment might be more important than time on CPB in determining ARF-D occurrence.