No solid evidence to guide this question. There are conflicting results from studies stating early initiation of RRT is beneficial in terms of mortality and renal recovery versus stating quite the opposite. We tend to begin CRRT if the patient fulfill criteria of a Rifle F, and I if he/she has fluid overload or acidosis etc.
Sorry, what do you mean - recomendations for acute or chronic RRT?
in our institution, the initiation of RRT is dependent on diseases severity and economic issues, as well as expectations of family members and patients. some emergencies such as hyperkalemia, severe acidosis and fluid overload mandates immediate RRT.
the AKIKI trial (Gaudry+Dreyfuss) will soon provide answers
in our department, urea is not a valuable criteria to initate RRT
see our experience in J Crit Care. 2014 Dec;29(6):1022-7. doi: 10.1016/j.jcrc.2014.07.014. Epub 2014 Jul 22.
Acute kidney injury in critical care: experience of a conservative strategy.
Here you'll find details on AKIKI study:
https://clinicaltrials.gov/ct2/show/NCT01932190?term=AKIKI&rank=1
not published yet, but surely might be in the next months
best,
JM