Augmented Renal Clearance: Prevalence, Risk Factors and Underlying Mechanism in Critically Ill Patients with Subarachnoid Hemorrhage

Background: Augmented renal clearance (ARC) is an increase in the measured creatinine clearance (CLCR), the cause of which remains poorly understood. ARC may be associated with drug underdosing and appears to be more frequent in patients with brain damage, such as subarachnoid hemorrhage (SaH), although the incidence of ARC remains poorly understood. The aim of this study was to investigate the prevalence of ARC in patients with SaH in a neurointensive care unit (neuro-ICU) and to identify factors associated with ARC.

Methods: All consecutive patients hospitalized in the neuro-ICU of Bordeaux University Hospital between June 2018 and June 2019 for SaH treatment were retrospectively included. CLCR was measured daily via 24-h urine collection. ARC was defined as a CLCR ≥ 130 mL/min/1.73 m². The effects of different covariates on the time course of CLCR were investigated using a linear mixed model.

Results: Of the 205 included study participants, 168 developed ARC during their neuro-ICU stay; the estimated ARC prevalence was 82% (95% confidence interval 76-87) with a median of 4 days (range 3-6 days) after hemorrhage; ARC persisted for a median of 5 days (range 2-8 days). Patients with ARC were younger and had a lower BMI and lower mortality rate. In multivariate analysis, younger patients with a higher mean arterial pressure, no history of hypertension, and greater nitrogen loss were more likely to have ARC.

Conclusions: Augmented renal clearance is very common in critically ill patients with SaH, persists over time, and seems to lack specific risk factors. Daily CLCR measurements could be essential.