Patient on Dialysis? The PCP's Role

Matthew F. Watto, MD; Paul N. Williams, MD; Stuart K. Brigham, MD


June 12, 2020

This transcript has been edited for clarity.

Matthew F. Watto, MD: I'm Matt Watto, here with my two wonderful cohosts. This is the Curbsiders.

Stuart K. Brigham, MD: Our guest was the one and only Joel Topf, who has many different nicknames and many different capes that he wears. He has the Freely Filtered podcast, he runs NephJC, and we like to call him Kidney Boy. In fact, he calls himself Kidney Boy. We're talking with him about dialysis. In this short video we're going to talk about Paul's favorite pearls and our pearls as well. So without further ado, Paul's pearl.

Paul N. Williams, MD: The less that I have to worry about, the happier I am. We talked with Topf about who's responsible for what in patients on dialysis. The things that I have to be a little less involved in would be the patient's volume status, because in a dialysis patient, that will be managed by the nephrologist. Nephrologists are also happy to manage anemia and mineral bone disease—things like playing with the calcium, phosphorus, and vitamin D levels. And by "playing with," I mean they do scientific stuff that I don't fully understand.

There's also a chance for us to be a bit more collaborative than we tend to be. Specifically, with hypertension, usually dialysis is the treatment, but if you are thinking about adjusting the patient's medications, or the interdialysis blood pressure is a little bit wonky, it's a chance to reach out and talk to your friendly neighborhood nephrologist and see if you can come to a shared decision and treatment plan that makes sense for that particular patient.

Watto: Joel made the point that the nephrologist actually appreciates it if we have extra blood pressure time points because they're only seeing the blood pressure on the dialysis days, and what the blood pressure is doing on the non-dialysis days is valuable information. For my tip, I'd say that fistulas and grafts have always been a bit of a mystery to me, so we asked about that. Topf talked about the physiology—that when they create an AV fistula, they're creating a connection between an artery and a vein that is meant to take 1.2 L of blood flow per minute, a very high flow rate—about 20% of the cardiac output.

During dialysis, they cannulate that fistula (once it's matured) and they take off about 400 mL of blood per minute. That's the flow rate that they need; they use very high flow rates in dialysis. It's kind of terrifying if one of those needles comes dislodged.

The other thing we asked about was how to differentiate an AV fistula from an AV graft when doing a physical exam. A mature fistula is big and tortuous. It should feel like a native vessel—softer—versus a graft, which usually feels firmer. With a graft, a foreign material is used to make the connection.

Stuart, what do you have?

Brigham: My pearl is about the use of semi-synthetic opioids, because I routinely see naturally occurring opioids being prescribed for dialysis patients—drugs like morphine and codeine, versus drugs like hydromorphone or fentanyl. In these patients, semi-synthetic opioids are much safer than naturally occurring opioids, which have active metabolites that are renally cleared, and thus accumulate in patients who are dialysis dependent. It's very important to avoid those drugs for patients who are on dialysis.

Watto: Right. And oxycodone is kind of the intermediate; you can use it, but you might have to space out dosing more and just be careful. Even though we think hydromorphone is the big, bad opioid that everyone's going to become addicted to, its actually the safest in these patients. That has come up on a couple of kidney podcasts, and we can't say that enough.

If all of this sounds great to you and you want to learn more about dialysis for the internist, or if you just want time hanging out with the great Dr Joel Topf, then please click on the link in this video to hear the full episode. You can also subscribe to our show and to our mailing list so that you can tune in weekly and get our show notes sent to your inbox weekly. So until next time, we've been the Curbsiders. Thank you for watching.

Click to hear the full episode of Dialysis for the Internist with Joel Topf, MD, or find the Curbsiders' podcasts on iTunes.

The Curbsiders is a national network of students, residents, and clinician educators from across the country, representing 15 different institutions. They "curbside" experts to deconstruct various topics in the world of medicine to provide listeners with clinical pearls, practice-changing knowledge, and bad puns. Learn more about their contributors and follow them on Twitter.

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