Renal Physiology During Continuous Renal Replacement Therapy

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.

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

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).

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

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

Using norepinephrine, patients will receive high or low blood pressure to start with and after measurements cross to receive the other blood pressure target

Changes in renal blood flow when CRRT is started? How will renal blood flow and oxygenation change at different blood pressure targets?

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)