An observational study in Doppler-Based Renal Ultrasound, Urinary Oxygen Tension and Acute Kidney Injury, sponsored by Tanta University. Recruiting at 1 site in Egypt. Open to participants aged 21 Years and older. Per ClinicalTrials.gov, last updated 2025-06-25.
Sponsored by Tanta University · Observational
This study aims to investigate the predictive value of Doppler-based renal ultrasound and urinary oxygen tension in the development of acute kidney injury after cardiac surgery.
Cardiac surgery-associated acute kidney injury (CSA-AKI) is a complication following cardiac surgery occurring in 15-30% of patients. It is associated with increased morbidity and mortality as well as prolonged hospital stay and higher medical costs.
The renal artery pulsatility index (RAPI), which is determined using Doppler measurements, has been reported to detect patients with a high risk of AKI. Additionally, the renal resistance index (RRI), measured by Doppler ultrasound, can accurately predict the occurrence of AKI.
Urinary oxygen partial pressure in the bladder has been shown to decrease in the setting of sepsis, reduced renal blood flow, and decreased cardiac output.
1,595 studies on the registry are indexed under Acute Kidney Injury; 371 are open to participants now.
This study's planned enrollment of 50 is below the median of 150 across 773 observational studies indexed under Acute Kidney Injury.
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This prospective cohort observational study will be conducted at Tanta University Hospitals for a period of at least two years, from October 2024 to September 2026, pending approval from the institutional ethics committee.
Exclusion Criteria:
Patients undergoing elective on-pump cardiac surgery
Other: Renal resistive index · Other: Renal Artery Pulsatility Index · Other: Urinary oxygen tension (PUO2)
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.
Number of cases developed acute kidney injury
Number of cases developed acute kidney injury as defined by KIDGO guidelines (serum creatinine ≥ 0.3 mg/dL from base line within 48 hours, or ≥1.5 fold within 7 days, or urine output \<0.5 mL/kg/hour for six hours) in patients undergoing open heart surgery.
Time frame: 7 days after the procedure
Length of intensive care unit stay
The length of stay in an Intensive Care Unit (ICU) is defined as the duration a patient spends in the ICU, typically measured from the time of admission to the ICU until the time of discharge.
Time frame: 7 days after the procedure
Length of hospital stay
Length of hospital stay will be measured from admission till discharge from hospital.
Time frame: 7 days after the procedure
Need for renal replacement therapy
Need for renal replacement therapy will be recorded.
Time frame: 7 days after the procedure
Number of patients developed chronic kidney disease
Number of patients developed chronic kidney disease will be recorded.
Time frame: 7 days after the procedure
Mortality rate
Mortality rate will be recorded.
Time frame: 7 days after the procedure
Plan to share: Yes — The data will be available upon a reasonable request from the corresponding author after the end of study for one year.
Supporting information: Study protocol
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