The study will examine the ability of renal ultrasound (Doppler and Contrast Enhanced Ultrasound (CEUS)) in distinguishing ICU patients who exhibit increases in GFR in response to fluid loading, from those for whom fluid loading is without benefit of directly harmful.~Patients available for inclusion will receive a baseline administration of Tc-99-DTPA for precise determination of GFR/renal function by blood and urine samples.~Baseline values of ultrasound measures will be obtained, including renal arterial, renal venous, portal venous and hepatic venous Doppler measures and renal contrast enhanced ultrasound (CEUS) will also be recorded.~After two hours, baseline values of GFR are finished. The patient is then exposed to passive leg raising and ultrasound measures are repeated, including renal arterial, renal venous, portal venous and hepatic venous Doppler measures.~The participant then receives a standardised fluid bolus of 7 ml/kg (ideal body weight) Once the fluid bolus administration is complete, renal ultrasound is repeated, including renal arterial, renal venous, portal venous, hepatic venous Doppler measures and renal CEUS.~Follow-up determination of GFR/renal function based on Tc-99-DTPA after fluid therapy is repeated with blood and urine samples.
The study will examine the ability of renal ultrasound (Doppler and Contrast Enhanced Ultrasound (CEUS)) in distinguishing ICU patients who exhibit increases in glomerular filtration rate (GFR) in response to fluid loading, from those for whom fluid loading is without benefit of directly harmful.