Plasma expansion and renal perfusion in critical COVID-19 with AKI: A prospective case control study.

Abstract

Introduction: A decrease in renal perfusion during acute kidney injury (AKI) due to critical COVID-19 has previously been demonstrated. The objective of this study was to compare the effects of plasma expansion with a standardized fluid bolus on renal perfusion in critically ill patients with AKI compared to similar patients without AKI.

Methods: A case control study design was used to investigate group differences before and after a standardized intervention. ICU-treated COVID-19 patients without underlying kidney disease were assigned to two groups based on KDIGO Creatinine criteria for AKI. Renal perfusion was assessed by magnetic resonance imaging using phase contrast and arterial spin labeling before and directly after plasma expansion with 7.5 mL/kg Ringer's Acetate (Baxter). Arithmetic means of mean arterial pressures (MAP) recorded before and after plasma infusion were compared. Data was analyzed with a mixed model repeated measures ANOVA for all kidneys using a random effect to account for research subjects.

Results: Nine patients with AKI and eight without were included in the study. The hemodynamic response to plasma expansion was similar in both groups, with increases in MAP by 9 mmHg (95% CI 0.5-18) and 15 mmHg (95% CI 5-24) in patients with and without AKI, respectively. Total renal perfusion and cortical perfusion were not significantly changed by plasma expansion in either group. There was a reduction of medullary perfusion in patients without AKI from 55 (95% CI 39-79) to 34 (95% CI 24-48) mL/min/100 g (p = .0027).

Conclusion: Plasma expansion with a standardized fluid bolus did not increase renal perfusion in critically ill patients with COVID-19, with or without AKI.