Renal Physiology During Continuous Renal Replacement Therapy

Study Overview
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Brief Summary
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Approximately 50% of patients in the intensive care unit (ICU) develop acute kidney injury (AKI) and more than 10% need dialysis. There is no treatment for AKI. Care is aiming for optimization of circulation and blood flow to the kidneys and avoiding nephrotoxic agents. There is conflicting data concerning whether early or late dialysis is harmful for the kidneys. No one has examined the physiological changes in the kidney when starting dialysis and which blood pressure that leads to most optimal physiological conditions for the kidneys during dialysis. In this descriptive study of 20 ICU patients suffering from AKI we aim to investigate renal physiology when starting continuous renal replacement therapy (CRRT) and also at different target blood pressures using retrograde renal vein thermodilution technique. In parallel we will also investigate and validate this invasive method with contrast enhanced ultrasound of the kidneys.

Official Title
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Impact of Continuous Renal Replacement Therapy on Renal Oxygenation, Blood Flow and Function

Conditions
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AKI, Continuous Renal Replacement Therapy, Dialysis, Intensive Care, Renal Blood Flow, Renal Failure, Blood Pressure

Intervention / Treatment
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* Other: Starting at high or low blood pressure


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: AKI, according to KDIGO, stage 2 or 3 but with preserved urine production. Treated in the ICU at Sahlgrenska University Hospital Written, signed informed consent Male and female subjects ≥18 years Exclusion Criteria: Emergency need for dialysis Allergy to contrast media (used for CEUS)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 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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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: To describe renal physiology parameters when starting CRRT and compare renal physiology parameters when using high blood pressure target (MAP 80-90 mmHg) and low blood pressure target (MAP 60-70 mmHg).
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Starting at high blood pressure<br>Patients in this arm are randomized to have high target blood pressure at MAP 80-90 mmHg during the first recordings, thereafter they will receive low blood pressure target 60-70 mm Hg | Other: Starting at high or low blood pressure<br>* Using norepinephrine, patients will receive high or low blood pressure to start with and after measurements cross to receive the other blood pressure target<br>|
| Experimental: Starting at low blood pressure<br>Patients in this arm are randomized to have low target blood pressure at MAP 60-70 mmHg during the first recordings, thereafter they will receive high blood pressure target 80-90 mm Hg | Other: Starting at high or low blood pressure<br>* Using norepinephrine, patients will receive high or low blood pressure to start with and after measurements cross to receive the other blood pressure target<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Renal blood flow and CRRT | Changes in renal blood flow when CRRT is started? How will renal blood flow and oxygenation change at different blood pressure targets? | 6 hours | 
| Renal blood flow and blood pressure | Renal blood flow changes at different mean arterial blood pressure targets during CRRT? | 6 hours | 
| Glomerular filtration rate (GFR) and blood pressure | GFR changes at different mean arterial blood pressure targets during CRRT? | 6 hours | 
| Glomerular filtration rate (GFR) and CRRT | Changes in GFR when CRRT is started? | 6 hours | 
| Renal oxygenation during CRRT | Renal oxygenation before CRRT and during CRRT | 6 hours | 
| Renal oxygenation and blood pressure | Renal oxygenation changes at different mean arterial blood pressure targets during CRRT? | 6 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Contrast enhanced renal ultrasound (CEUS) | Validation of CEUS compared to retrograde renal vein thermodilution in measuring renal blood flow | 2 hours | 
| atrial natriuretic peptide (ANP) | Differences in serum atrial natriuretic peptide (ANP) during CRRT | 6 hours |