Background: Acute kidney injury (AKI) is the most frequent extra-pulmonary organ failure in acute respiratory distress syndrome (ARDS). The objective of this study was to assess the factors associated with the development and severity of AKI in patients with ARDS.
Methods: This is a retrospective cohort study of ARDS patients without acute or chronic kidney disease prior to the onset of ARDS over a 7-year period (2010-2017). AKI and severity of AKI were defined according to the Kidney Disease Improving Global Outcomes 2012 guidelines.
Results: Of the 634 ARDS patients, 357 patients met study criteria. A total of 244 (68.3%) patients developed AKI after ARDS onset: 60 (24.6%) had stage I AKI, 66 (27%) had stage II AKI, and 118 (48.4%) had stage III AKI. The median time of AKI onset for stage I AKI was 2 days (interquartile range, 1.5-5.5) while stage II and III AKI was 4 days. On multivariable analysis, factors associated with development of AKI were age [subdistribution hazard ratio (SHR) 1.01, 95% confidence interval (CI) 1.00-1.02], SOFA score (SHR 1.16, 95%CI 1.12-1.21), a history of diabetes mellitus (DM) (SHR 1.42, 95%CI 1.07-1.89), and arterial pH on day 1 of ARDS (SHR per 0.1 units decrease was 1.18, 95%CI 1.05-1.32). In severity of AKI, stage I AKI was associated with age (SHR 1.03, 95%CI 1.01-1.05) and serum bicarbonate on day 1 of ARDS (SHR 1.07, 95%CI 1.02-1.13). Stage II AKI was associated with age (SHR 1.03, 95%CI 1.01-1.05), serum bicarbonate on day 1 (SHR 1.12, 95%CI 1.06-1.18), SOFA score (SHR 1.19, 95%CI 1.10-1.30), history of heart failure (SHR 3.71, 95%CI 1.63-8.46), and peak airway pressure (SHR 1.04, 95%CI 1.00-1.07). Stage III AKI was associated with a higher BMI (SHR 1.02, 95%CI 1.00-1.03), a history of DM (SHR 1.79, 95%CI 1.18-2.72), SOFA score (SHR 1.29, 95%CI 1.22-1.36), and arterial pH on day 1 (SHR per 0.1 units decrease was 1.25, 95%CI 1.05-1.49).
Conclusions: Age, a higher severity of illness, a history of diabetes, and acidosis were associated with development of AKI in ARDS patients. Severity of AKI was further associated with BMI, history of heart failure, and peak airway pressure.
Keywords: Acute kidney injury; Acute respiratory distress syndrome; Gas exchange; Lung protective ventilation; Mechanical ventilation; Septic shock.