Fluctuations in Serum Chloride and Acute Kidney Injury among Critically Ill Patients: A Retrospective Association Study

Exposure to dyschloremia among critically ill patients is associated with an increased risk of acute kidney injury (AKI). We aimed to investigate how fluctuations in serum chloride (Cl(−)) are associated with the development of AKI in critically ill patients. We retrospectively analyzed medical records of adult patients admitted to the intensive care unit (ICU) between January 2012 and December 2017. Positive and negative fluctuations in Cl(−) were defined as the difference between the baseline Cl- and maximum Cl- levels and the difference between the baseline Cl(−) and minimum Cl(−) levels measured within 72 h after ICU admission, respectively. In total, 19,707 patients were included. The odds of developing AKI increased 1.06-fold for every 1 mmol L(−1) increase in the positive fluctuations in Cl(−) (odds ratio: 1.06; 95% confidence interval: 1.04 to 1.08; p < 0.001) and 1.04-fold for every 1 mmol L(−1) increase in the negative fluctuations in Cl(−) (odds ratio: 1.04; 95% confidence interval: 1.02 to 1.06; p < 0.001). Increases in both the positive and negative fluctuations in Cl- after ICU admission were associated with an increased risk of AKI. Furthermore, these associations differed based on the functional status of the kidneys at ICU admission or postoperative ICU admission.