A New Way to Treat Kidney Stones with Adam Maxwell

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Travis

What do know about kidney stones? I thankfully only know about them through second hand experiences, but I think it's safe to say the user reviews for both having them and dealing with them is zero of ten, would not repeat. So when I heard that Virginia Tech's Adam Maxwell was working on developing treatment that could help make them a little bit easier to deal with, I simply had to know more. And thankfully Adam was kind enough to jump on the podcast and answer all the questions that I had. Adam is a research associate professor in the Department of Biomedical Engineering. His research interests include the bio-effects of ultrasound, elastic waves in biomaterials, ultrasound and laser lithotripsy, and the veterinary applications of ultrasounds. So Adam and I talked about lithotripsy, which is a medical procedure to break of our kidney stones. He shared some of the current methods and ways that physicians can go about helping patients with kidney stones and what some of the challenges are there for both the patient and the physicians. Then we talked a little about a new technique that he and his colleagues have just received FDA approval for, which he thinks could really be a game changer in this area and could help folks maybe even deal with kidney stones right there in their doctor's offices. So while kidney stones may not be the most pleasurable thing to talk about, hopefully this episode

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Travis

⁓ So I guess the most obvious place to start is simply what is is lithotripsy?

Adam

 Sure. So lithotripsy is a medical procedure to break apart calcifications in the body. And so any any medical procedure where where this is involved could be called lithotripsy. And in the case of kidney stones, which is one of the main conditions that I study, you do this to break the stone apart when it's obstructing a part of the urinary tract. So this could be in the kidneys, in the ureters, and even you can get bladder stones. But the goal is really to break a stone apart into small fragments so that you can either pull them out endoscopically or that the patient can then just naturally pass the fragments through their urinary tract and relieve the obstruction.

Travis

Do you use ultrasounds to do this? I understanding that correctly?

Adam

Yeah. So there's right now, if you were to go get treated for a kidney stone, there's a couple of different technologies that are used for lithotripsy. One is called shockwave lithotripsy. And so these are ultrasonic shock waves that are non-invasively delivered by a large machine that fires them through your skin and focuses them onto a kidney stone to shatter it apart. And that usually takes about 40 minutes to an hour. And the other procedure that's typically done is called laserless trypsia where they introduce a small endoscope that goes up your urinary tract. You're under anesthesia at this point for sure. And it fires laser pulses from a fiber optic laser that uses the stone to blast it apart. And that usually can take like one to two hours. But these are fairly common procedures. And so they probably account for about 90 % of all the procedures that are done for stones today. Okay. So both of those though fall under this broader category of lithotripsy. Yeah. And so I guess then what makes what you're doing different from the shock waves and the lasers? So what we're doing that's different is really we're changing the type of ultrasound that's being applied to the stone. So instead of using shock waves, we're using harmonic ultrasound pulses, similar to what they use out of like an ultrasound imager or in focused ultrasound therapy to create the stresses that you need to fracture a stone in the body. And so you've probably seen like a cartoon of an opera singer shattering a wine glass with their voice. It's something like that. It's not exactly like that, but that's the general idea. Whereas conversely, you can think of shockwave lithotripsy as you're hitting the wine glass impulsively with a hammer over and over again to shatter it. But one of the things about even just changing the type of ultrasound wave that you're applying to the stone changes a lot of the physical aspects of how you're breaking the stones apart, like what technology you can use to deliver that treatment and then how the patient is going to experience it when you do this therapy.

Travis

Yeah, the shockwave part, and I forget if someone told me this or not that it's had kidney stones, that doesn't sound like the most comfortable experience for a patient. Is that accurate?

Adam

Fortunately, I have not had to experience it firsthand, but I've talked to, you know, a lot of patients who've had both of the two procedures that I just talked about and they both are definitely uncomfortable. So shockwave lyso-tripsy itself is quite painful and usually it has to be done under anesthesia or very heavy sedation. They administer 2,000 shockwaves about once a second. so it just, one patient told me, said, it feels like you're just getting hit in the back over and over again. So usually they have the patients under for it when they're doing it. But it also causes damage to your kidney. And they know as a fact, it bruises your kidney when they do this and patients often get repeat lissotripsies as they get stones throughout their life. And so there's a concern that, you you're actually damaging the kidney tissue in addition to just experiencing the procedure itself.

Travis

Yeah, that makes a lot of sense to me. What besides perhaps the pain of the procedure or the discomfort of the procedure?probably a better way to say that. What are some of the other challenges with the current way we treat kidney stones?

Adam

Well, the way that we like manage stones in general, if you get a stone, your physician will want to assess how large that stone is. And so if it's about four millimeters or smaller, usually they won't they won't choose to intervene because a four millimeter stone can pass through the urinary tract or if it's smaller than that, it can pass through the urinary tract. So they'll do what's called observation or watchful waiting where they'll send you home maybe with some pain medication and say, go see if it passes in the next couple of weeks. And for many patients, they want them removed immediately, especially those who've had a stone before rather than have the anxiety of waiting days or weeks for it to pass or the possibility of being in debilitating pain and having to go to the emergency room once it gets painful. So for a lot ⁓ of patients, that's one of the big challenges is just that it's not worth the intervention to treat these small stones when they can pass, being an unpleasant experience.

If your stone is five millimeters or larger, it's not likely to pass through the urinary tract. And so at that point they'll say, okay, we need to do something. And shockwave lithotripsy is the only non-invasive way of doing it in clinic right now. But in addition to the pain and the trauma that it causes to the tissue, the other problem is that it only is successful about 60 to 70 % of the time. And so, you know, 30 to 40 % of the time they will say, oh, you still have a kidney stone or you still have large fragments of stone in your kidney and we need to try another treatment. And the other problem is we don't immediately know right after the treatment if we were successful. So what we're doing with shockwave lithotripsies, you're breaking the stone into fragments, but then the fragments just sit in the kidney until they hopefully pass naturally. And so you have to wait between when you get the treatment and usually like four to six weeks before they're going to re-image your kidney using like an x-ray CT system to assess whether the stones are gone. And it's that part that a lot of the physicians really don't like administering a treatment to the patients and then sending them off and hoping it was successful. They want to know it was successful right after the fact.

Travis

Yeah, you just got beat up. It might work. It might not, but...

Adam

You know, it's in different news after such a procedure. The alternative is to get laser lithotripsy, which is the endoscopic procedure. And that's more invasive obviously, and it has some risks of complications like infection or bleeding if something happens with the instrumentation. You also have to be under general anesthesia for it. And so with both of these, you have to be in like an outpatient room or in a surgical suite to conduct them. But a lot of patients say that the post procedural pain from getting a laser lithotripsy is worse. In some cases, it's worse than the stone was. And so a lot of patients prefer shockwave lithotripsy because it's less invasive and they feel there's less like post procedural pain. But a lot of physicians like laser lithotripsy because it's more definitive and more successful because they can see immediately that they've removed the stone or the fragments or that they've completely fragmented the stone through the scope that they're using. And so there's kind of this imbalance between what the patient preferences and what physicians often prefer with these procedures. Yeah.

Travis

Well, I know that you all just got FDA approval, I believe, for a new type of treatment. And so I'm curious what that is and maybe...How does it help overcome some of the situation, the challenges that you just went through?

Adam

Yeah, ⁓ so what I was talking about before with the technology to use harmonic waves rather than shock waves to break apart stones, that's the technology that just received FDA approval last month in January. And this was something that we developed as a new type of non-invasive lithotripsy. I was part of a large multi-institutional team that developed. My role was really leading much of the scientific, the technological and the preclinical studies to understand how to even make it feasible to do a treatment in humans. And that took probably about ⁓ six or seven years of work. But after that, a lot of the attention shifted over to the clinical trials and the other members of the team were leading that program. And so I wasn't as much involved with the human trials, but those have been going on over the last...about six years. Simultaneous with the preclinical development, we co-founded a company called Sauna Motion and they were responsible for developing a commercial version of this technology and they did multiple clinical trials to get this eventually approved by the FDA recently. I'm sorry, there was the second part of your question I'm blanking on.

Travis

Well, that's okay. That's really fascinating just the process and the time that it takes. I don't think most people realize how long it takes to just develop things and how much work goes into it. I'm curious, what is it, when I'm trying to wrap my mind around this, what does it look like?

Adam

So the device itself is, it looks a lot like an ultrasound imager. It's a small cart with a screen and that's in part because it's ultrasound image guided. So we use ultrasound imaging to target the stone and align the ultrasound device that we're using to treat with the stone. So the actual device that emits the ultrasound to break the stone just looks like a large ultrasound imaging probe and it's held in the hand and it's placed against the patient the same way that you would with an ultrasound imager. You apply gel to the patient and then push it against the patient's back to treat, say, a stone in the kidney. And this is very distinct from...what you would find with a shock waveless tripter, which is a much larger piece of high voltage equipment that has to be installed in like an outpatient suite. And it's a fairly demanding procedure just to align it with the patient's stone. Typically that involves both x-ray imaging, like a fluoroscope, to align the focus of that with the stone. And then they sometimes use ultrasound imaging in conjunction with that. So the idea is that, you know, this machine is a potentially smaller, less expensive machine that looks like an ultrasound imager and you could just wheel it into the clinic and use it like, apply it like an ultrasound imager and it would be a more, a simpler process. And I'm assuming that because it's the operasing and not the punch, maybe it feels is more comfortable for the patient? Yeah. So that's, that's one of the benefits that we've discovered and is that is appears to be much less painful than a shockwave lithotrypter. So the acoustic pressure that we're using is considerably lower than what the acoustic pressure of like one of the shock waves using a shockwave lithotripsy is. And so generally it's not, from the patient's accounts, it's not, not painful. And so we're, we've been applying it in awake patients who aren't being sedated or under anesthesia. And sometimes they're just in their street clothes on a patient table. And so we think, you know One is that it's less painful. The other is that we think it's also potentially safer to the kidney because we're applying lower levels of pressure to the kidney. And some of our preclinical studies showed that there was very minimal injury to the kidney compared to a shockwave lithotripsy as well.

Travis

Yeah, that makes a lot of sense to me. How does it do as far as a physician being able to maybe predict how successful it is? I know you mentioned with the shockwave stuff ahead of. a little bit of a fluctuating success rate. we can't say at this point that it's more successful than shockwave lithotripsy.

Adam

So in the, least in the initial trials, it had a success rate that was similar to a shockwave lithotripsy like 60, I think, or a little bit above that in terms of how many patients it rendered stone free. So that's a part of it that I'm very interested in tackling in our future research because really this device being this kind of low pressure, safe, simpler way of doing this procedure is really only one way in which you could, it's really only one form that the device could take. We could potentially make a high pressure version of this technology that is considerably more efficient and more effective and advance it that way as well. But we've really concentrated our efforts on making this more like a first line treatment for stones that you say. You go in and get treated before you need something that's more invasive and whether or not it's more successful.

Travis

you've kind of answered some of this, but maybe we can, I'm going to ask you, think, to put it all together. How do you hope this might change how a person gets their kidney stones treated initially?

Adam

Yeah, there is kind of a big picture for the Senate, you know, might change several things. One is it might change. how you're treated ⁓ in that you don't need, if you don't need anesthesia, you can be treated potentially in a doctor's office rather than needing to schedule an outpatient procedure or a surgical procedure for your stone. So you can receive that care sooner rather than waiting to be scheduled for one of these more invasive procedures. Another way in which we think about it is that it's also where and who we can treat. So because this technology is potentially cheaper and doesn't require as much infrastructure, you can potentially introduce this into a lot of other places all around the world. And it can be more involved in like primary care rather than only being installed in say major hospitals. In addition, we think that because it's considerably, considerably safer and doesn't require anesthesia, it may have some role in treating stones that are smaller than five millimeters. So like I said before, patients who have stones that are under five millimeters, they typically just watch them and wait for them to pass. But a lot of the patients want those stones treated immediately and have that peace of mind that the stone has been broken up and they're less likely to encounter the pain of having a kidney stone. And so we think that this opens an avenue to saying, Here's a good option for treating those stones that are four millimeters and under rather than just waiting for them to pass.

Travis

Yeah, waiting for, that sounds awful to me. mean, just to be completely honest, like waiting for something like that from everything that I have heard, I too have never had a kidney stone, but I've had relatives that have had them, not a fun experience that they ever want to repeat. Zero out of 10 would not do again, is part of how they rate that. So, certainly being able to prevent, then it will treat that.

Sounds like it would be a great situation as well as what you mentioned about being able to take this into areas that maybe don't have the infrastructure of a hospital. Because I know there's a lot of areas even in Virginia where people maybe struggle to get to a hospital. So that's fascinating.

Adam

Yeah. I mean, in the U S it's very, very unusual that you would get an open surgery for removing a kidney stone with all the minimally invasive and noninvasive options they have.

They probably only do a hundred or 200 cases of open stone surgery in the U S but in other countries, it's a, it's a massive number of people who just get open surgery for stones because they don't have the infrastructure or the technology available to them. And in part, because a lot of this is expensive capital equipment or it requires a lot of specialized training to use. So if the procedure can be made simpler and more affordable, then you can start replacing open surgery and all its complications with something that's not invasive, which would be fantastic.

Travis

That is fascinating. Well, I guess the last question that I want to ask you is just simply, what do you most want for people to know about this work and what you all are doing?

Adam

That's probably the hardest question, I guess. Maybe it's just because it's the most open-ended one, but I guess what I'd like people to know is that we really do feel that this can change how stones are managed kind of comprehensively because it introduces this new layer of treatment or this new way in which people could be treated more simply than some of the more surgical procedures. But also that even though it took a long time to develop, it really was developed down one specific path to make it this accessible and this simple. And there's a lot of other research out there to be done with it to make

The other, make it reach its full potential, I guess, is the best way to say it. So there's a lot of challenges still with how do you, how do you image the stones? How do you use imaging when you're doing a non-invasive procedure to determine where a stone is, what its characteristics are, whether you can use that to treat it more effectively. And then say, after you've treated it, how can you tell? that it's completely destroyed and that you have a good outcome. Like I was saying before, the doctors don't know right now when they go to do one of these non-invasive treatments, if the treatment was successful immediately after. So if we can introduce some tools into this and make the image guidance for it better, so that they can be more confident that they did or didn't destroy, they can also respond faster to determining the next steps for that patient's care.

That's, guess the succinct way of saying it is even though, you know, a lot of work has gone into it to get it this far, this is really just opening the door for us as researchers to start exploring all the ways in which this technology could potentially be used ⁓ in treating kidney stones and other calcifications and also the other applications for it that it might be useful. So our group now is studying how we can potentially use this to treat vascular calcifications, which are like very stiffened arteries due to things like peripheral artery disease. Can we fracture the calcifications in arteries to make them more compliant and reduce the morbidity from that disease?

Travis

So it sounds like that we're going to have more podcasts to do in the future. So what you're telling me.

Adam

Potentially there will be another one in another 12 years. Hopefully not that long.

Travis

Hopefully sooner than that.

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Travis

And thanks to Adam for helping us better understand lithotripsy and perhaps a better way to treat kidney stones. If you or someone you know would make for a great curious conversation, email me at traviskw.vt.edu. I'm Travis Williams, this has been Virginia Tech's Curious Conversations.

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