A recent study presented at the American Urological Association 2025 Annual Meeting in Las Vegas, Nevada, evaluated intrarenal pressure using the CVAC System vs standard flexible ureteroscopy.1 In this interview, Roger Sur, MD, discusses the study, emphasizing the crucial aspect of safety in new medical technologies. The study’s primary objective was to assess the effect of CVAC on intrarenal pressures, a known risk factor for complications like infection, bleeding, and postoperative pain.
Using a highly sensitive pressure-sensing guide wire, the investigators found no significant difference in intrarenal pressures between the CVAC and standard ureteroscopy groups. Sur explains that although CVAC involves constant irrigation, it also incorporates continuous aspiration, creating a “net zero” effect that maintains stable intrarenal pressures. This balance ensures that the new technology does not increase intrarenal pressures, addressing a key safety concern.
Beyond intrarenal pressure, the multi-institutional ASPIRE trial further investigated CVAC’s advantages, examining stone-free rates and long-term downstream events. This trial demonstrated that patients treated with CVAC had a significantly lower rate of health care-related events. Sur said he also anticipates that CVAC’s effectiveness may lead to fewer percutaneous nephrolithotomy procedures, reducing patient complications and health care costs.
Ultimately, these findings reassure urologists that aspiration technology like CVAC is as safe as standard ureteroscopy while offering superior stone-free rates and lower infection rates, making it a preferable choice for stone management.
Urology Times: Please provide an overview of this study and its notable findings.
Sur: This abstract was very important to us, and I think to many others, because with new technology, you want to make sure that the technology is the same, if not better, than current, existing technology. The most important thing for any technology or any new device, or anything new within medicine, is safety. It’s got to be safe. What we learn in medical school is the Latin phrase “Primum non nocere.” That means, “First, do no harm.” We don’t want to hurt people whenever we do things. That being said, we wanted to know, what is the effect of CVAC on intrarenal pressures, because it’s thought that intrarenal pressure is a risk factor for complications. Specifically, infection is a big one, but it can be associated with other things like bleeding and postoperative pain.
We have a really nice study here, because it’s a prospective trial. We had patients who had CVAC used to remove kidney stones, and then we had patients who underwent standard flexible ureteroscopy to remove the stones. For each of these cases, we would put up this pressure-sensing guide wire. It measures, I think, 250 measurements per second, so very sensitive pressure readings. In fact, it’s so sensitive that we couldn’t really use standard techniques to calculate things. We prospectively collected [data], so it was not retrospective. We had a clinical research coordinator where everything was followed closely, and so the purity and the homogeneity of the data are [was] really good. What we showed was that there’s no difference in the pressures whether you use CVAC or standard ureteroscopy. CVAC did not increase the intrarenal pressures. And so, in its most simplistic fashion, that is what was important to us and I think to the audience and to patients.
Urology Times: Given the comparable intrarenal pressures observed between the CVAC and standard ureteroscopy groups, could you elaborate on the specific mechanisms within the CVAC System that contribute to maintaining these similar pressure profiles despite the integrated irrigation and aspiration?
Sur: What’s different about CVAC compared with standard ureteroscopy are multiple things, but I think what people worry about is the constant irrigation of the system—does that increase their intrarenal pressures? But what our study showed was, we not only have constant irrigation going in to raise the pressure, but we have constant aspiration going on with the scope to reduce the pressure. The balance of the irrigation and the aspiration leads to a net zero. There’s no increase in pressure, nor was there a decrease in pressure, so if I were to guess, that would be my explanation as to why the CVAC system showed no difference in pressure. It’s the ability to irrigate and aspirate continuously throughout the case.
Urology Times: The abstract mentions a trend toward a greater average number of stones in the non-CVAC group. How might this difference in stone burden potentially influence IRP measurements in either group, and were any statistical adjustments made to account for this disparity in your analysis?
Sur: Although there were more stones in the non-CVAC group, what’s important is not the number of stones, but the total stone burden. What I mean by that is, when you total up all the stones in millimeters; let’s say there are 2 5-mm stones in 1 case, but then you have a single 10-mm stone in another case. Well, 5 and 5 is 10, so they’re equal. You might have 2 stones, but they’re smaller stones. In this case, we may have had more stones in the non-CVAC cases, but the overall axial diameter of the stone burden was similar between the 2 groups.
Urology Times: Beyond IRP, what other potential advantages or disadvantages of the CVAC system, such as procedural efficiency, stone-free rates, or visualization during lithotripsy, warrant further investigation and comparison to standard ureteroscopy in future studies?
Sur: There’s a multi-institutional study called the ASPIRE trial. In that trial, we not only looked at stone-free rates, which is the immediate thing everyone wants to know—did you remove all the stones—but we looked at downstream events such as, if you do a really good job removing the stones, are these patients less likely to come back to the ER? Are they less likely to be admitted for some kind of a stone-related event? Are they less likely to have an infection? Because we know that once you have a stone, that doesn’t necessarily mean it’s the last time you have a stone. So if you do a really good job of removing stones, what’s its effect downstream? It’s a long-term event that’s very important to not just the patients, actually, [but also to the] health care systems. Because when you bounce back, guess who has to pay? There’s a lot [at stake] here when patients have to return, or they have complications, or you stay in the hospital for a week. What we showed in this abstract was that patients who had the CVAC vs traditional/standard of care URS had a much lower rate of health care consumption events, or HCE. That’s what Dr [Brian] Matlaga had written in his paper. That’s a huge advantage to the CVAC that we saw in this paper. Another advantage is that I predict we’re probably going to have to do fewer PCNLs. If you can avoid putting a needle and dilating the kidney, you might be saving the patient complications. That has a huge financial implication for the health care system.
Urology Times: Considering the potential for pyelovenous backflow and associated morbidity with elevated IRP, how do these findings regarding comparable IRP between the two techniques inform your clinical decision-making when selecting a stone management approach?
Sur: I think it goes back to [what I said earlier], that it reassures the urologist that using an aspiration technology poses no greater risk to the patient, and if you consider the fact that most people now accept that aspiration technology has superior stone-free rates—that’s been shown in a meta analysis and a systematic review—as well as lower infectious rates. That’s also been demonstrated in systematic review and meta analysis. Since it’s better than standard ureteroscopy, and as long as it’s safer or just as safe, why not use the better technology? That’s how it’s informed me, is that it’s reassured me that I can use a better technology and be just as safe as the standard technology.
REFERENCE
1. Berrios SE, Katz JE, Finegan JL, et al.Impact of steerable ureteroscopic renal evacuation (SURE) using CVAC on intrarenal pressure.J Urol. 2025;213(5S2):e38. doi:10.1097/01.JU.0001109712.09934.41.09