Does the Inferior Vena Cava Size Assessment Help in the Management of Acute Kidney Injury in Critically Ill Patients?

Consecutive patients presenting to the intensive care unit with a diagnosis of acute renal failure (defined as a 1.5 fold increase in plasma Creatinine level compared to baseline ).

Baseline characteristics will be recorded and followed for each patient, these include:

1. Demographics
2. Medical history
3. Hemodynamic parameter such as Central Venous Pressure (CVP), Mean Arterial Pressure (MAP) , and measurement of superior vena cava (SVC) size by ultrasound.
4. Laboratory parameter such as chemistry, fractional excretion of sodium , fractional excretion of urea , beta natriuretic peptide , albumin
5. Radiographic parameters
6. Echocardiographic parameters including Left Ventricular Ejection Fraction (LVEF), Right Ventricular (RV) function and IVC size and variations
7. Mechanical ventilation
8. Daily fluid balance

Focused bedside ultrasound will be performed for each patient as part of their routine care and initial assessment. The IVC size will be measured at the subcostal window, during inspiration and expiration, using the (Sonosite) Cardiac probe P-21 (5-1 MHZ). The measurement is obtained by applying the M-mode, perpendicular to the IVC axis and 2 cm caudal from its junction with the right atrium.

In spontaneously breathing, non-ventilated patients, we will calculate the IVC collapsibility index (IVC-CI) = [IVC max-IVC min]/IVC max.