Outline the clinical scenarios in which you would consider
instituting dialysis in the critically ill.
Dialytic techniques in the critically ill are becoming more widely used. Traditional indications used for acute renal failure, are concerns about fluid overload (actual or to facilitate nutritional support), hyperkalaemia or other uncontrolled electrolyte disorders, metabolic acidosis, hyponatraemia, uraemic symptoms or elevated urea (e.g. 30 mmol/L). As complications associated with techniques have been minimised, dialysis is often initiated earlier (anticipatory, oliguria, lower urea), and even for non-renal indications (including sepsis or septic shock). Dialysis or haemofiltration (e.g. with charcoal filter) can be used to increase the clearance of toxic products from the circulation (e.g. lithium, theophylline, myoglobin). Newer related extracorporeal techniques have also been developed to support liver dysfunction.
The question really asks "what are the indications for dialysis"?
A good resource for information about this topic is adqi.org, home of the Acute Dialysis Quality Initiative. Particularly, their "reports" section contains a series of recommendations for commencement of dialysis in AKI. Most of these recommendations are based on expert opinion rather than strong evidence.
In summary, the indications for dialysis are as follows:
Guided by expert opinion and the IDEAL trial of 2010 (no mortality difference between early and late dialysis groups)
The current (2011) guidelines suggest the following:
Cooper, Bruce A., et al. "A randomized, controlled trial of early versus late initiation of dialysis." New England Journal of Medicine 363.7 (2010): 609-619.
Tattersall, James, et al. "When to start dialysis: updated guidance following publication of the Initiating Dialysis Early and Late (IDEAL) study." Nephrology dialysis transplantation (2011): gfr168.