Effects of intraoperative tidal volume on incidence of acute kidney injury after cardiovascular surgery: A retrospective cohort study

Abstract

PurposeWe performed a retrospective cohort study to evaluate whether intraoperative low tidal volume ventilation reduces the incidence of acute kidney injury (AKI) after cardiovascular surgery. Materials and methodsRecords of patients who underwent cardiovascular surgery were reviewed. The primary outcome was AKI diagnosed by changes in serum creatinine values. Intraoperative mean tidal volume relative to predicted body weight (PBW) was calculated. The effects of intraoperative mean tidal volumes on AKI incidence were evaluated. ResultsOf 338 examined patients, 105 developed AKI. Among patients who received mean tidal volumes of ≤7, >7 to ≤8, >8 to ≤9, and > 9 mL/kg PBW, the AKI incidence was 12.8% (95% confidence interval [CI]: 6.0–25.1%), 29.9% (95% CI: 22.6–38.4%), 38.7% (95% CI: 30.0–48.2), and 34.5% (95% CI: 23.6–47.3%), respectively. Inverse probability of treatment weighting analysis demonstrated that AKI risk was significantly lower in patients who received ≤7 mL/kg PBW than in those who received >7 mL/kg PBW (odds ratio: 0.14, 95% CI: 0.04–0.46, p = .001). ConclusionsThis study suggests that intraoperative low tidal volume ventilation during cardiovascular surgery is associated with a decreased incidence of postoperative AKI. Lowering tidal volume might be a simple strategy for reducing AKI incidence after cardiovascular surgery.