Acute Kidney Injury Following Mannitol Infusion in Neurosurgical Patients

Background: To evaluate the acute kidney injury (AKI) predictors and their predictive performance during mannitol infusion, and the impact of AKI on in-hospital mortality of neurocritically ill patients.Methods: This was a retrospective, observational study of patients who were admitted at a tertiary university hospital, Seoul, Republic of Korea, neurosurgical intensive care unit (ICU) from January 2013 to December 2019. We included neurosurgical patients on mannitol infusion admitted in the ICU The primary endpoint was the occurrence of AKI.Results: A total of 3,964 patients were included in the final analysis. AKI was detected in 540 (13.6%) patients on mannitol infusion. Measured osmolality and osmolar gap were significantly higher in patients with AKI than those without (both p< 0.001). However, the predictive power of the two indicators was similar and were both weak predictors of AKI (both C-statistic <0.650). In the multivariable analysis, maximal measured osmolality, chronic kidney disease, Acute Physiology and Chronic Health Evaluation 2 score on ICU admission, use of vasopressor, use of glycerin, mechanical ventilation, and invasive ICP monitoring were significantly associated with AKI. In-hospital mortality was significantly higher in patients with AKI than those without (11.1% vs. 1.4%, p< 0.001).Conclusions: Based on our findings, kidney injury may be associated with poor clinical outcomes in neurosurgical and neurocritically ill patients, and monitoring serum osmolality and OG remains important in the prevention of kidney injury for patients on mannitol infusion. Moreover, clinical factors related to ICU management and pre-existing renal disease may aggravate AKI during mannitol infusion.