Portal Flow Pulsatility as a Risk Factor for Acute Kidney Injury After Cardiac Surgery

Study Overview
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Brief Summary
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The purpose of this study is to evaluate the possible association between portal vein flow pulsatility and acute kidney injury after cardiac surgery. Participants will undergo assessment of portal vein flow and intra-renal blood flow using bedside Doppler ultrasound before surgery and daily for three days after cardiac surgery.

Detailed Description
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Acute kidney injury is a frequent complication after cardiac surgery. Venous congestion from right ventricular dysfunction and fluid overload can impair kidney perfusion resulting in the cardio-renal syndrome. An increase in the variation of blood flow velocity in the portal vein during the cardiac cycle called portal pulsatility is a sign of congestive heart failure. Portal pulsatility occurs when increased central venous pressure results liver venous congestion. The presence of abnormal portal pulsatility could be used as a marker of venous congestions in other organs such as the kidneys. Discontinuous intra-renal vein flow is a risk factor for death or re-hospitalization in heart failure patients and could be seen in patients with portal pulsatility.

Official Title
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Assessment of Portal Flow Using Bedside Doppler Ultrasonography for the Detection of Portal Pulsatility as a Risk Factor for Acute Kidney Injury in Cardiac Surgery Patients

Conditions
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C.Surgical Procedure; Cardiac, Acute Kidney Injury, Postoperative Complications, Right-Sided Heart Failure, Cardio-Renal Syndrome

Intervention / Treatment
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* Procedure: Cardiac surgery


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18 years and older. Undergoing cardiac surgery with the use of cardiopulmonary bypass Able to provide consent. Exclusion Criteria: Chronic renal replacement therapy before the procedure. Chronic kidney disease stage 5 defined as a estimated glomerular filtration rate by the MDRD equation (eGFR-MDRD) of 15 mL/min/1,73m2 or less. Critical pre-operative state defined as aborted sudden death, preoperative cardiac massage, preoperative ventilation before anaesthetic room, preoperative inotropes or intra-aortic counterpulsation balloon. Patients previously diagnosed with a condition interfering with Doppler evaluation of the portal system: Portal vein thrombosis, Cirrhosis. Patients with documented AKI before surgery. Confirmed or suspected pregnancy. Kidney transplant recipients.

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 |
| --- | --- |
| Cardiac surgery patients<br>Adult patients having a cardiac surgery at the Montreal Heart Institute | Procedure: Cardiac surgery<br>* All cardiac surgery procedures with the use of cardiopulmonary bypass<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Acute kidney injury defined by an increase in serum creatinine of ≥150% of baseline or an elevation of 0.3 mg/dL or more within a contiguous period of 48 hours. (KDIGO criteria) | The definition of acute kidney injury is based on the KDIGO guidelines | 7 days after surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mortality |  | 30 days after surgery | 
| Duration of intensive care stay |  | 30 days after surgery | 
| Delirium defined as an Intensive Care Delirium Screening Checklist score of 4 or more. | Intensive Care Delirium Screening Checklist is a validated tool for the screening of delirium in the intensive care unit. | 7 days after surgery | 
| Composite endpoint of persistent organ dysfunction (POD) plus death at day 3 and 7 | Persistent organ dysfunction (POD) plus death is a validated outcome measure in cardiac surgery patients. It is defined as one of the following: mechanical ventilation without breaks for a period of more than 48 hours or vasopressor therapy (ongoing need for vasopressor agents such as norepinephrine, epinephrine, vasopressin, dopamine 45 μg/ kg/min, or phenylephrine 450 μg/min for more than 2 hours in a given day); or mechanical circulatory support (ongoing need for mechanical devices such as extracorporeal membrane oxygenation or intra-aortic counterpulsation balloon pump) or continuous renal replacement therapy or new intermittent hemodialysis; or death. | 3 days and 7 days after surgery | 
| Severe acute kidney injury (KDIGO stage 2 or more) defined by an increase in serum creatinine of ≥200% of baseline. | The definition of acute kidney injury is based on the KDIGO guidelines | 7 days after surgery | 
| Discontinuous blow flow in renal interlobar vessels | The presence of abnormal discontinuous blow flow in renal interlobar vessels assessed by bedside Doppler ultrasound. | 3 days after surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Ultrasonography, Portal vein Doppler, Renal Doppler, Cardio-Intestinal syndrome, Delirium, Renal congestion, Intra-renal hemodynamics