The Predictive Value of Doppler Based Renal Ultrasound and Urinary Oxygen Tension for Prediction of Acute Kidney Injury After Open Heart Surgery

It will be measured with ultrasound-Doppler using an abdominal curvilinear probe ultrasonography by two independent, trained sonographers (who will not be involved in patient care). After visualizing the kidney in ultrasound mode and checking for renal abnormalities, an arcuate or inter-lobar artery will be localized, and three successive Doppler measurements at different positions in the kidney (high, middle, and low) will be performed. The average value for each kidney will be taken. The renal resistive index will be calculated as follows: (systolic peak flow velocity - diastolic minimum flow velocity)/systolic peak flow velocity

It will be measured using an abdominal curvilinear probe ultrasonography by two independent, trained sonographers (who will not be involved in patient care). After visualizing the kidney, the interlobular artery will be located using color Doppler mode, and the velocity of the interlobular arteries will be assessed in one or two kidneys. The Renal Artery Pulsatility Index (RAPI) will be calculated as follows: RAPI = \[(peak systolic velocity) - (end diastolic velocity)\] /average velocity

Urinary oxygen tension (PUO2) will be measured preoperatively (baseline), postoperatively just after intensive care unit admission, 12 hours after surgery, and then once daily for 7 days.