Effect of hyperchloremia on acute kidney injury in critically ill septic patients: a retrospective cohort study

Background: Hyperchloremia is common in critically ill septic patients. The impact of hyperchloremia on the incidence of acute kidney injury (AKI) is not well studied. We investigated the association between hyperchloremia and AKI within the first 72 h of intensive care unit (ICU) admission. Methods: 6490 ICU adult patients admitted with severe sepsis or septic shock were screened for eligibility. Exclusion criteria included: AKI on admission, baseline estimated glomerular filtration rate (eGFR) < 15 ml/min/1. 73 m(2), chronic renal replacement therapy, absent baseline serum creatinine data, and absent serum chloride data on ICU admission. Results: A total of 1045 patients were available for analysis following the implementation of eligibility criteria: 303 (29%) had hyperchloremia (Cl-0 >= 110 mEq/L) on ICU admission, 561 (54%) were normochloremic (Cl-0 101-109 mEq/L) and 181 (17%) were hypochloremic (Cl-0 <= 100 mEq/L). AKI within the first 72 h of ICU stay was the dependent variable. Chloride on ICU admission (Cl0) and change in Cl by 72 h (Delta Cl = Cl-72 - Cl-0) were the independent variables. The odds for AKI were not different in the hyperchloremic group when compared to the normochloremic group [adjusted odds ratio (OR) = 0.80, 95% confidence interval [CI] (0.51-1.25); p = 0.33] after adjusting for demographics, comorbidities, baseline kidney function, drug exposure and critical illness indicators including cumulative fluid balance and base deficit. Furthermore, within the subgroup of patients with hyperchloremia on ICU admission, neither Cl-0 nor Delta Cl was associated with AKI or with moderate/severe AKI (KDIGO Stage >= 2). Conclusions: Hyperchloremia occurs commonly among critically ill septic patients admitted to the ICU, but does not appear to be associated with an increased risk for AKI within the first 72 h of admission.