This has been discussed between the renal division and the cardiac surgery division in my institution. We know that AKI post cardiac surgery is an independent prognostic factor for mortality (Am J Nephrology 2010 31 408). It’s a big deal! But what can we do about it?
The etiology for AKI post cardiac surgery is multi-factorial but one of them is the length of time on cardiopulmonary bypass. Postulated mechanisms are the inflammatory response, ischemia, micro-embolization of gaseous particles, etc. (Perfusion 2006 21 209). One may then wonder if off-pump CABG would prevent post-op AKI and reduce mortality.
The answer comes from a recent study (NEJM 2012 366 1489) showing that the off-pump CABG group had fewer episodes of AKI (defined as a creatine rise of more than 0.3 mg/dl), 28% v. 32% (p = 0.01). However, the 30-day mortality was not different between off-pump and on-pump CABG... It is speculated that this may be due to intra-operative hypotension, technical issues, etc.
What about the CKD patients who are yet to be on dialysis? Would they benefit from “prophylactic” dialysis? Well, this is a controversial topic with only 3 studies looking into it… 1 is from West Virginia and 2 are fromTurkey . Here’s the summary of each study.
The 2 of them showed a benefit on mortality (the single most important quality the surgeons are looked upon), hospital stay and post-operative complications.
However, each study has flaws. All of them are single-center, 2 of them are not randomized, and 1 of them is retrospective. AKI was not defined well and there is a bias that creatinine rise will be masked in patient who received dialysis. Their indications for post-op dialysis are not the standard. No difference was observed in terms of likelihood of requiring long-term dialysis.
I don’t think we have good evidence to support prophylactic dialysis. In my institution, we ended up dialyzing a couple of patients at a request from cardiac surgeons. As always, we need better studies. And if there is a potential benefit in prophylactic dialysis, the question would be what the benefit is due to (ultrafiltration versus clearance).
Posted by Tomoki Tsukahara.