Management - further

If the fluid challenges have been given, and there has been no response to the frusemide, the next stage is to site a central venous line to get a clear idea of what is actually going on - ie has the patient been adequately rehydrated, are they in heart failure, etc. The column of fluid is lined up with the sternal notch or mid axillary point; the normal value is anywhere from 0 to 6cm. The physician is looking for some sort of response to a fluid challenge, interpreted as follows:-

• full - pressure up and stays up for at least an hour
• not full - pressure rises but falls within 15 minutes

The patient should be resuscitated accordingly.

Dopamine was previously thought helpful in AKI, but this has not been born out in studies, and Kidney Disease Improving Global Outcomes guidelines advise against its use. (2) Fenoldopam is a selective dopamine-1 agonist that has been shown to reduce the need for renal replacement therapy although this has only been consistently demonstrated in patients having undergone cardiac surgery, and its use is limited by its ability to cause systemic hypotension. Atrial natriuretic peptide (ANP) effectively reduces the need for RRT in post-cardiac surgery patients, yet, like fenoldopam, its utility is limited by systemic hypotension. (3)

Reference

1. Romagnoli S, Ricci Z, Ronco C. Therapy of acute kidney injury in the perioperative setting. Curr Opin Anaesthesiol. 2017 Feb;30(1):92-99.
2. Lameire NH et al. Harmonizing acute and chronic kidney disease definition and classification: report of a Kidney Disease: Improving Global Outcomes (KDIGO) Consensus Conference. Kidney Int. 2021 Sep;100(3):516-526.
3. Calvert S, Shaw A. Perioperative acute kidney injury. Perioper Med (Lond). 2012;1:6