Central venous pressure and the risk of diuretic-associated acute kidney injury in patients after cardiac surgery.

backgroundWhen prescribing diuretics in the postcardiac surgical intensive care unit (ICU), clinicians may use central venous pressure (CVP) to assess volume status and the risk of acute kidney injury (AKI). In this study, we examined how the risk of diuretic-associated AKI varied with CVP in patients undergoing cardiac surgery.

methodsWe used the Medical Information Mart for Intensive Care database to study adults admitted to the postcardiac surgical ICU at an urban, academic medical center between 2001 and 2012. We examined the odds of AKI per 1-mm Hg increase in CVP among patients receiving intravenous loop diuretics using multivariable adjusted logistic regression. We examined the risk of AKI among patients with diuretic use (vs nonuse) across tertiles of CVP using inverse probability treatment weighting.

resultsAmong 4,164 patients receiving intravenous loop diuretics, the adjusted odds of subsequent AKI were 1.11 (95% CI 1.08-1.13) times higher per mm Hg increase in mean CVP. This association was log-linear across the entire range of CVPs observed. In the analysis of diuretic use (n = 5,396), the adjusted risk ratio for AKI with diuretic use (vs nonuse) was 1.33 (95% CI 1.21-1.47) and did not materially differ across tertile of CVP.

conclusionsHigher rather than lower CVP is an independent marker of AKI risk. The risk of AKI associated with diuretic use may not be influenced by CVP. Novel methods of assessing volume status and AKI risk are needed to guide patient selection for diuretic therapy.