Acute Kidney Injury and Delirium: Kidney–Brain Crosstalk

Acute kidney injury-associated delirium: a review of clinical and pathophysiological mechanisms

Acute kidney injury is a known clinical risk factor for delirium, an acute cognitive dysfunction that is commonly encountered in the critically ill population. In this comprehensive review of clinical and basic research studies, we detail the epidemiology, clinical implications, pathogenesis, and management strategies of patients with acute kidney injury-associated delirium. Specifically addressed are the pathological roles of endogenous toxin or drug accumulation, acute kidney injury-mediated neuroinflammation, and acute kidney injury-associated volume overload as discrete potential biological mechanisms of the condition. The optimization of clinical contributors and normalization of renal function are reviewed as pragmatic management strategies in addition to potential and emerging therapeutic approaches.

The Impact of Acute Kidney Injury in the Perioperative Period on the Incidence of Postoperative Delirium in Patients Undergoing Coronary Artery Bypass Grafting-Observational Cohort Study

Recent data indicate that acute kidney damage leads to inflammation in the brain and other distant organs. The purpose of this study was to investigate the effect of acute kidney injury (AKI) according to the Kidney Disease Improving Global Outcome (KDIGO) criteria on the occurrence of postoperative delirium in patients undergoing coronary artery bypass grafting (CABG). We performed a retrospective cohort analysis that included all consecutive patients undergoing elective CABG. The CAM-ICU (Confusion Assessment Method for Intensive Care Unit) was used for delirium assessment. Patients were divided into four groups, depending on the occurrence of AKI in the perioperative period according to KDIGO criteria. Overall, 902 patients were included in the final analysis, the mean age was 65.95 ± 8.01 years, and 76.83% were males (693/957). The majority of patients presented with normal kidney function-baseline creatinine level of 0.91 ± 0.21 (mg/dL). The incidence of AKI in the perioperative setting was 22.17% (200/902). Postoperative delirium was diagnosed in 115/902 patients (12.75%). Compared with no AKI, the odds of developing POD were increased for KDIGO stage 1 (OR 2.401 (95% confidence interval 1.484–3.884), p < 0.001); KDIGO stage 2 (OR 3.387 (95% confidence interval 1.459–7.866), p = 0.005); and highest for KDIGO stage 3 (OR equal to 9.729 (95% confidence interval 2.675–35.382), p = 0.001). Acute kidney injury, based on AKI staging, should be regarded as an independent risk factor for postoperative delirium after cardiac surgery.

Acute kidney injury as a risk factor of hyperactive delirium: A case control study

PURPOSE

Delirium and acute kidney injury (AKI) are common organ dysfunctions during critical illness. Both conditions are associated with serious short- and long-term complications. We investigated whether AKI is a risk factor for hyperactive delirium.

METHODS

This was a single-centre case control study conducted in a 30 bedded mixed Intensive Care Unit in the UK. Hyperactive delirium cases were identified by antipsychotic initiation and confirmation of delirium diagnosis through validated chart review. Cases were compared with non-delirium controls matched by Acute Physiology and Chronic Health Evaluation II score and gender. AKI was defined by the KDIGO criteria.

RESULTS

142 cases and 142 matched controls were identified. AKI stage 3 was independently associated with hyperactive delirium [Odds ratio (OR) 5.40 (95% confidence interval (CI) 2.33-12.51]. Other independent risk factors were mechanical ventilation [OR 2.70 (95% CI 1.40-5.21)], alcohol use disorder [OR 5.80 (95% CI 1.90-17.72)], and dementia [OR 9.76 (95% CI 1.09-87.56)]. Hospital length of stay was significantly longer in delirium cases (29 versus 20 days; p = .004) but hospital mortality was not different.

CONCLUSIONS

AKI stage 3 is independently associated with hyperactive delirium. Further research is required to explore the factors that contribute to this association.