The Relationship Between IRRIV and RFR Under Pathologic Conditions

Study Overview
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Brief Summary
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The assessment of renal functional reserve (RFR) has been proposed for the risk stratification of patients undergoing potentially nephrotoxic procedures. The present pilot study is designed to explore the correlation between IRRIV and RFR under pathologic conditions.

Detailed Description
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Renal functional reserve (RFR) represents the capacity of the kidney to increase glomerular filtration rate (GFR) in response to certain physiological or pathological stimuli or conditions. RFR is calculated as the difference between the measured maximum GFR achieved through a renal stress test and the baseline GFR measured in rest conditions. In clinical practice, the most common renal stress test is performed as a standardized protein loading test. Recently, in a pilot study, the investigators demonstrated a significant correlation between RFR and the intra-parenchymal renal resistive index variation (IRRIV) during an echo renal stress test in a cohort of healthy volunteers. IRRIV test has proven to be rapid, safe, bedside and easy to perform and it might represent a preliminary test in screening patients' RFR.The present pilot study is designed to explore the correlation between IRRIV and RFR under pathologic conditions.

Official Title
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The Relationship Between IRRIV and RFR Under Pathologic Conditions

Conditions
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Acute Kidney Injury

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Estimated GFR (CKD-EPI) greater than or equal to 60 mL/min/1.73 m2 Scheduled cardiac surgery with cardiopulmonary bypass (coronary artery bypass, valve replacements, combined or other operations). Exclusion Criteria: Age less than 18 years old Pregnancy Ultrasound evidence of morphological kidney abnormalities and/or renal artery stenosis Nonsteroidal anti-inflammatory drugs (NSAIDs) Contrast media in the 2 days before the tests.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| IRRIV and RFR<br>Enrolled patients will receive IRRIV test and RFR assessment. RFR will be evaluated through a protein loading test. (1.2 g of protein/Kg of body weight) performed with cooked beef. The RFR was then defined as the difference between the highest CrCl obtained after the protein load and the baseline CrCl measured on rest conditions. Concerning the IRRIV test, a weight of 10% of the patient's body weight is applied on the abdominal wall. RRIs is recorded in a middle interlobular artery, every minute for 10 minutes during the echo-renal stress test. The lowest RRI reached is taken as reference (stress RRI). The IRRIV is defined as the percentage difference between baseline RRI and stress RRI | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Correlation between IRRIV test and RFR in cardiac surgery patients | IRRIV test and RFR will be determined and a relationship will be assessed | Change from baseline to 60 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Concordance between IRRIV test and RFR in cardiac surgery patients | Concordance between presence of RFR (i.e. a RFR≥15ml/min/1.73m2) and a positive/uncertain/negative IRRIV is evaluated. | Change from baseline to 60 minutes |