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Abstract
Rationale: Acute kidney injury may contribute to distant organ dysfunction. Few studies have examined kidney injury as a risk factor for delirium and coma.
Objectives: To examine whether acute kidney injury is associated with delirium and coma in critically ill adults.
Methods: In a prospective cohort study of intensive care unit patients with respiratory failure and/or shock, we examined the association between acute kidney injury and daily mental status using multinomial transition models adjusting for demographics, nonrenal organ failure, sepsis, prior mental status, and sedative exposure. Acute kidney injury was characterized daily using the difference between baseline and peak serum creatinine and staged according to Kidney Disease Improving Global Outcomes criteria. Mental status (normal vs. delirium vs. coma) was assessed daily with the Confusion Assessment Method for the ICU and Richmond Agitation-Sedation Scale.
Measurements and Main Results: Among 466 patients, stage 2 acute kidney injury was a risk factor for delirium (odds ratio [OR], 1.55; 95% confidence interval [Cl], 1.07-2.26) and coma (OR, 2.04; 95% Cl, 1.25-3.34) as was stage 3 injury (OR for delirium, 2.56; 95% Cl, 1.57-4.16) (OR for coma, 3.34; 95% Cl, 1.85-6.03). Daily peak serum creatinine (adjusted for baseline) values were also associated with delirium (OR, 1.35; 95% Cl, 1.18-1.55) and coma (OR, 1.44; 95% Cl, 1.20-1.74). Renal replacement therapy modified the association between stage 3 acute kidney injury and daily peak serum creatinine and both delirium and coma.
Conclusions: Acute kidney injury is a risk factor for delirium and coma during critical illness.
Keywords: acute kidney injury; delirium; coma; critical illness
The kidney and the brain are frequently injured during critical illness. Acute kidney injury, which affects up to half of critically ill patients (1), is strongly associated with shortand long-term morbidity and mortality (2-7). Similarly, acute brain dysfunction, which manifests as delirium or coma in the intensive care unit (ICU), is common during critical illness and associated with adverse short- and long-term outcomes. Delirium and coma both predict increased mortality and delirium has been associated with long-term cognitive impairment in survivors of critical illness (8-15).
One mechanism by which acute kidney injury may contribute to poor outcomes is through effects on distant organ function (16-22). Recent experimental data indicate that acute kidney injury can lead to inflammation...