In a sea change between 2015-2020, we stopped frantically worrying about iv iodinated contrast exploding patients' kidneys if their baseline renal function was good. But what open those patients with poor renal function? This question keeps coming up, so I figured I would find someone brilliant to ask. When it comes to the beans, there is nobody better than:
Joel Topf, MD
Dr. Topf is the Medical Director of St. Clair Nephrology. He is the author of two medical textbooks: The Microbiology Companion and The Fluid, Electrolyte and Acid-Base Companion. He blogs at the Precious Bodily Fluids website.
So this week, we hit kidney issues, in a week or so, for members only, we will do
Contrast-Associated Nephropathy with Normal Kidneys
Basically, you don't need to think about this anymore
Recs from Rads and Kidney Societies
Use of Intravenous Iodinated Contrast Media in Patients With Kidney Disease: Consensus Statements From the American College of Radiology and the National Kidney Foundation. Radiology. 2020 Mar;294(3):660-668. doi: 10.1148/radiol.2019192094.
Although the true risk of CI-AKI remains uncertain for patients with severe kidney disease, prophylaxis with intravenous normal saline is indicated for patients who have AKI or an estimated glomerular filtration rate less than 30 mL/min/1.73 m2 who are not undergoing maintenance dialysis. In individual high-risk circumstances, prophylaxis may be considered in patients with an estimated glomerular filtration rate of 30-44 mL/min/1.73 m2 at the discretion of the ordering clinician
Retrospective Trial demonstrated no association in Patients with Normal Renal Function
[10.1016/j.annemergmed.2016.11.021]
Meta-Analysis Stating the Same
[10.1007/s00134-017-4700-9]
Prophylaxis Doesn't Seem to Work (AMACING Trial), Maybe b/c CIN isn't Real?
Low Osmolar Non-Ionic Agents May Be Associated with Less Kidney Injury in General
It is Probably an Association
One study found that more than 50 percent of hospitalized patients not given contrast material developed an increase in creatinine of at least 25%. (AJR Am J Roentgenol 2008;191[2]:376.)
Papers discussing association without causation [Acad Emerg Med ]2012;19(11):1261] & [Radiology 2013;267(1):106]
In Critically Ill Patients with Normal Renal Function
[10.1016/j.chest.2019.10.005]
Study Using D-Dimer as a Matching Mechanism Showed No Difference
[]
NEJM Review 2019
What About Patients with Poor Renal Function
Dr. Topf starts to worry when GFR<20 with albinuria
Mehran Score for Risk of Progression to Dialysis after PCI Contrast
on MdCalc
Kidney Failure Risk Equation
For Seeing Patient's Likelihood of Progression
Which Contrast Agents?
In general, non-ionic low and iso-osmolar are safer, but some of the LOCMs have still been associated with a slightly higher risk
Best Paper Studying Patients with Poor GFR
What are Others Saying?
Additional New Information
Does Nitrate CIN point to the continued risk of contrast injury in patients at risk [10.1093/eurheartj/ehae100/7633084]
Contrast injury in Cath Labs, correlation? [10.1016/j.jacc.2024.01.016]
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I’m always more concerned with the consequences of missing an important diagnosis (thus a needed intervention) than with any possible minor kidney injury eventually caused by the use of contrast (which I’m not fully confident that really happens…).
my friend,
with great respect, can I ask–did you actually listen to the podcast?
Hi Scott, Yes, I did listen and greatly enjoyed it. So much so that I highlighted what I think is the main take-home message. Unfortunately, I still see patients being denied proper diagnostic workup for fear of contrast-induced renal failure. I feel doctors in general greatly overestimate the risks and are not aware of any prediction score or formula to help with it. All in all, this was a very informative discussion on such an important topic. It’s nice to interact with you here, but you seemed a bit annoyed by my first comment. I hope I made myself clearer… Read more »
appreciate that–thanks, just needed to make sure. Often folks will post a comment that is exactly what the podcast said b/c they just read the blog post. I think we agree that serious diagnosis trumps everything, but what would you do in this situation:
GFR <20
strong suspicion of a PE, no right strain, no contraindications to anticoagulation, no DVT. V/Q scan available the next day, but not today, (it’s after 2pm and the nuke techs have gone fishing)
I think we should just put them on the LMW and wait till the next day.
What do you think?
Agree with you, Scott, would treat and but diagnose later on. Risk/benefit just doesn’t seem worth it for CT vs VQ scan. Even though CT risk is low, it still exists and I’m going to feel really bad if I need to dialyze someone over a non-existent PE.
I agree, Paul. Seems we often think of PE w anything resembling CP because we don’t want to miss it. We get a lot of negatives–which may be part of the territory.
Good point, I think it’s a nice compromise.
Scott…would you put them on LMWH with a GFR les than 20? and if you put them on a drip then the benefit of waiting a day is less clear I think.
it’s a great point. i think if they are in-pt, UFH is not a problem. But if they are safe for d/c, you can just put them on something like Apixiban and have them get out-pt study for V/Q
Regarding your questions at show’s end: I think a pre-renal injury or AKI with ATN will behave similarly to advanced CKD. GFR and tubular flow is low in all states, which allows cell injury as that contrast sits in the tubules. Would just approach similarly to how Dr Topf outlines contrast use in CKD during the show. Difference may be that many oliguric ICU patients will be on dialysis or close to dialysis for other more immediate reasons (septic shock with hyperK, respiratory failure with volume overload etc) when we are debating this contrast issue and it usually becomes a… Read more »
Paul,
Joel’s answers mirrored yours exactly! I love the Intensive Care Nephrologists out there–have you folks broken into the double digits yet in numbers. I think it is only going to grow.
Nice, looking forward to further explanation from Joel. Always educational. Neph-Crit is definitely catching on, more combined fellowship programs are increasing visibility. Diversity of training and experience in critical care lately has really been a positive.
Another thing to consider, is a pt that might have contrast again in the next 48hours, such as a heart cath. I’ve seen this renal injury. Also, if bicarb and mucmyst cause no harm, why not give it to protect. Maybe it helps a minority. And if we don’t need the contrast, why give it just to make a prettier picture?
Hi Scott and Joel, Thanks for the excellent podcast. Although I think you were careful in your framing of the question, and so the conclusions as stated are probably entirely correct, and I think your overall message is good, I worry about the consequences of that conclusion that you don’t fully explore. By focusing only on the tiny subset that you do (the patients with very low eGFRs) are we overlooking the significant harms to all other patients that comes from that focus? In order to identify this subset, we require all patients to have blood work. We delay important… Read more »
“we should proceed as if contrast has exactly no impact on kidneys and completely drop the requirement for bloodwork” very well stated, Justin. I totally agree. Further, you made quite a fundamental question here: “is there a single properly controlled study that shows any harm from contrast?” I don’t cover this issue so closely, but one thing that strikes me is that, in basically every study I’ve seen, contrast nephropathy is defined solely by the rise in serum creatinine. So, may I ask you if you know of any reliable study using a more direct and specific mesure of renal… Read more »
so now this is a slightly different question, very similar to clinical clearance of the c-spine with a negative CT in a patient who is obtunded vs. a patient who has clear midline tenderness.(by the way, I think the CT is fine for both of these patient groups, but the trauma surgeons disagree in the latter group) i completely agree that labwork requirements before CT should be COMPLETELY eliminated as they do more harm than good. And I would almost rather get the scan before labwork comes back than wait for it and have to deal with thinking this through.… Read more »
Thanks Scott I know that we are on the same page for the patient that you are talking about. And I actually agree with everything you are saying. If a scan isn’t 100% necessary, or if there is an adequate alternative (ie VQ scan), it might make sense to consider contrast exposure in these high risk patients. However, in the absence of any evidence of harm, my concern about any conversation that focuses on eGFR is the underlying assumption that eGFR is important, which subtly reinforces the practice of getting bloodwork before scans, which ultimately makes it harder for us… Read more »
“However, in the absence of any evidence of harm, my concern about any conversation that focuses on eGFR is the underlying assumption that eGFR is important, …which subtly reinforces the practice of getting bloodwork before scans, ” Succinctly put!
well I appreciate your opinion, David
but best doesn’t mean good. this is the best available lit on the topic–I too wish it was better but we have to work with what we got…