Augmented renal clearance in critically ill trauma patients: A pathophysiologic approach using renal vascular index

Abstract

Background: The aim of the present study was to explore the relationship between creatinine clearance (ClCr), cardiac index (CI) and renal vascular index (RVI) in order to assess the potential mechanisms driving ARC in critically ill trauma patient. The secondary objective was to assess the performance of RVI for prediction of ARC.

Methods: Every trauma patient who underwent cardiac and renal ultrasound measurements during their initial ICU management was retrospectively reviewed over a 3-month period. ARC was defined by a 24-hr measured ClCr ≥ 130 mL/min/1.73m². A mixed effect model was constructed to explore covariates associated with ClCr over time. The performance of RVI for prediction of ARC was assessed by receiver operating characteristic (ROC) curve and compared to the ARCTIC (ARC in trauma intensive care) predictive scoring model.

Results: Thirty patients, contributing for 121 coupled physiologic data, were retrospectively analysed. There was a significant correlation between ClCr values and RVI (r = -0.495; P = 0.005) but not between ClCr and CI values (r = 0.023; P = 0.967) at day 1. Using a mixed effect model, only age remained associated with ClCr variations over time. The area under the ROC curve of RVI for predicting ARC was 0.742 (95% CI: 0.649-0.834; P < 0.0001), with statistical difference when compared to the ROC curve of ARCTIC [0.842 (0.771-0.913); P < 0.0001].

Conclusion: Ultrasonic evaluation of CI and RVI did not allow approaching the haemodynamic mechanisms responsible for ARC in patients. RVI was inaccurate and not better than clinical score for predicting ARC.

Keywords: Augmented renal clearance; Critical illness; Renal ultrasound; Renal vascular index; Trauma.