Intrarenal Venous Flow Change During Fluid Removal in Critically Ill Patients: A Prospective Exploratory Study

Background: In patients with heart failure, intrarenal venous flow patterns could change depending on the level of congestion and was strongly correlated with death from cardiovascular disease and unplanned hospitalization. However, the findings may differ in patients with sepsis in the intensive care unit. In this case, Intrarenal venous flow patterns were not associated with Central Venous Pressure but were associated with Acute Kidney Injury and death. This suggests that intrarenal venous flow patterns may serve as an indicator of renal congestion and could be a feasible bedside tool to predict various clinical implications. In addition, Point-of-care ultrasound (POCUS) techniques such as Venous Excess Ultrasound (VExUS) and Lung Ultrasound (LUS) provide non-invasive assessments of fluid status and venous congestion. This study evaluates changes in VExUS and LUS scores during fluid removal to predict clinical outcomes in critically ill patients.

Objective: We aimed to study intrarenal venous flow patterns change, VExUS score change, and LUS score change during fluid removal treatment in critically ill patients.

Methods:

• After enrollment, patients will undergo baseline Doppler ultrasonography to evaluate intrarenal venous flow patterns and LUS before the initiation of fluid removal through diuretic therapy or renal replacement therapy.
• After patients received fluid removal therapy, they will receive continuous ultrasonography monitoring within 24, 48, and 72 hours, along with data collection.

Researchers will collect data about

• intrarenal venous flow patterns change, Venous Excess Ultrasound (VExUS) score change, and LUS score change during fluid removal treatment
• establish a correlation between alterations in intrarenal flow patterns, VExUS score, and LUS score as well as other clinical data (Central venous pressure, Cumulative fluid balance) and clinical implications (Renal replacement therapy free day, Ventilator free day, length of Intensive care unit stay).

Inclusion criteria

• Adult patients aged 18 years old or older who will be admitted to the medical intensive care unit
• Expected to be hospitalized in the intensive care unit for more than 120 hours.
• The patient has stable vital signs without the need for vasoactive medications or rapid fluid resuscitation (at least 500 milliliters of colloid or 1000 milliliters of crystalloid via rapid intravenous infusion) for a minimum consecutive period of 12 hours. This includes cases where the patient receives norepinephrine at a rate not exceeding 0.1 micrograms per kilogram per minute and dobutamine at a rate not exceeding 10 micrograms per kilogram per minute, or when the patient can maintain a continuous reduction in vasoactive medications for a minimum consecutive period of 12 hours.
• The patient does not exhibit signs suggestive of inadequate organ perfusion, such as mottling skin, a capillary refill time of more than 2 seconds when nailbeds are pressed and released, or cold extremities.
• The patients require fluid removal through decisions made by attending staff or clinical guidelines, which may involve the administration of diuretics or Renal Replacement Therapy.

Exclusion criteria

• Underlying chronic kidney disease (eGFR< 30) before enrollment
• Chronic renal replacement therapy (RRT) before enrollment such as on intermittent hemodialysis, peritoneal dialysis
• Decompensated cirrhosis with portal hypertension
• Inferior vena cava, portal vein, hepatic, renal vein thrombosis
• Ureteral obstruction
• Intraabdominal hypertension (Intraabdominal pressure > 12 mmHg)
• Previous allergic or anaphylactic to diuretic
• Pregnant women
• Transplanted kidney, transplanted liver
• Patients with do-not-resuscitate (DNR) orders or decisions to withhold life-sustaining treatments
• Patients or their legally authorized representatives (LAR), who decline participation in the study or are unable to provide informed consent before enrollment