Effect of Furosemide on Urinary Oxygenation in Patients with Septic Shock

Background: Renal medullary hypoxia precedes the development of acute kidney injury in experimental sepsis and can now be assessed by continuous measurement of urinary oxygen tension (PuO2). Objectives: We aimed to test if PuO2 measurements in patients with septic shock would be similar to those shown in experimental sepsis and would detect changes induced by the administration of furosemide. Method: Pilot prospective observational cohort study in a tertiary intensive care unit (ICU). Seven adult patients with septic shock admitted to ICU had PuO2 measurements recorded minutely. There were 29 episodes of intravenous furosemide (20 mg n = 19; 40 mg n = 10). Results: The median pre-furosemide PuO2 was low at 21.2 mm Hg (interquartile range [IQR] 17.73-24.86) and increased to 26 mm Hg (IQR 20.27-29.95) at 20 min (p < 0.01), to 27.5 mm Hg (IQR 24.06-33.18) at 40 min (p < 0.01) and to 28.5 mm Hg (IQR 22.65-31.03) at 60 min (p < 0.01). The increase in PuO2 was greater in episodes with a diuretic response >2 mL/kg/h than during episodes without such a response (p < 0.01). Conclusions: PuO2 measurements in patients are reflective of the low values reported in experimental models of sepsis. PuO2 values increased following furosemide administration with a response independently associated with greater diuresis.