When treating kidney stones, debate continues over the use of dusting versus basketing. In this interview, Olivier Traxer, MD, (pictured) describes both methods, lists his preferred laser settings, and explains why he changed the way he uses ureteral access sheaths. Dr. Traxer is professor of urology at Sorbonne University, Hospital Tenon, Paris. He was interviewed by Urology Times Editorial Consultant Stephen Y. Nakada, MD, the Uehling Professor and founding chairman of urology at the University of Wisconsin, Madison.
Please describe dusting and basketing.
“Dusting” means that you produce very tiny particles when you treat stones. We don’t have a clear definition of “dust” itself. When you fragment a stone, you produce small pieces from 1 to a few mm in size. Those are fragments. But what actually constitutes “dust,” nobody knows exactly. My personal definition is the production of tiny fragments that are floating when I irrigate with 40 cm H2O pressure. Because of this low density, they’re amenable to evacuation.
“Basketing” means that the surgeon catches stone fragments with a basket and removes them. Both dusting and fragmentation are techniques to produce pieces of stone. When you’re dusting, you expect to produce only very tiny pieces, and then that dust is supposed to evacuate. When you’re fragmenting, you expect to produce pieces but then you have to remove them with basketing.
Of the two techniques, which do you prefer and why?
It’s really difficult to say. I like both techniques. I make the choice based on each patient and the characteristics of each stone—composition and volume. Sometimes I prefer to dust, sometimes I prefer to fragment, and sometimes I have to do both for the same patient.
If you’re doing dusting, how do you get the stone composition?
The problem with the dusting technique is that you never produce only dust. You regularly produce a few small pieces—fragments. If you use a basket to remove these small pieces, then you can obtain the stone composition.
When you’re using one technique or another, you don’t produce only dust with dusting and only fragments with fragmenting. When I’m dusting, at the end I produce a few pieces to basket and use them for my stone analysis.
Can you tell me what the typical laser settings are for dusting compared to fragmenting?
In the last 15 years, we’ve developed a much better understanding of how the holmium laser works. We know now that if we adjust the different parameters of the laser, we are able to produce dust or fragments.
For dusting, I recommend using long-pulse duration if possible. Not all lasers allow surgeons to do it, but if it’s possible, select long-pulse duration and low energy—.2-.3 J.
For fragmentation, it’s just the opposite. You need to select short-pulse duration, high energy—1, 1.2, 1.5 J; it depends on the composition and resistance of the stone—and low frequency to allow the system to produce a high energy level.
Do you think most urologists should have a variable pulse laser?
The new machines include all these parameters. Pulse duration is not a new concept because we have known about it for many years, but it’s new in the sense that we can adjust the pulse duration today.
It’s true that for urologists, it’s a bit difficult sometimes to know exactly how to set the laser, and I would say that the laser companies should help the urologist make this decision with very simple tools to select the appropriate settings.
You mentioned dusting and basketing in terms of how you treat patients and even how you might do a hybrid technique. Could you describe the typical patient you would dust and the typical patient you would basket?
The main characteristics I use to make the decision are stone volume and composition. For the stone volume, when we are talking about a stone 1 cm in diameter, that means in terms of volume, it is 0.5 cm3. If we are talking about a 2-cm stone, its volume is 4 cm3.
For me, the limit is 1 cm. If it’s less than 1 cm, I prefer to fragment the stone because I will produce a few pieces and basket them. If the stone is more than 1 cm, then it becomes difficult to only fragment because you will produce a lot of pieces. For example, if you fragment a 2-cm stone into pieces of 5 mm, you produce approximately 64 pieces. That means you have to go in and out to remove the pieces 64 times, which is really difficult to do. For me, if the stone is more than, say, 10 to 12 mm, I prefer first to dust the stone to reduce the size and maybe switch to fragmentation at the end if it’s a hard stone like calcium oxalate monohydrate. If it’s a soft one, I will just proceed with dusting.
What do you think the typical practicing urologist should do, assuming it’s difficult to learn both techniques?
If you look at the recent publications, we are seeing that about 65% of urologists prefer dusting. My explanation is that it may be easier because you stay in the kidney and you just have to move the fiber on the surface of the stone to produce tiny pieces and have nothing to remove. You save some equipment because you don’t use baskets and you don’t have to go into the kidney multiple times, which is not very easy. I would say probably the easiest technique is dusting, but we also know that using only the dusting technique, the stone-free rate is not as good as with basketing. So again, I recommend a combination of techniques, and the urologist may want to move from one technique to the other.
Do you use ureteral access sheaths routinely to remove fragments, and do you believe they’re safe?
Our group published a paper some years ago regarding the lesions associated with ureteral access sheaths (J Urol 2013; 189:580-4). At the time, we were using big access sheaths: minimum of 12/14F. We were forcing the placements. When we felt some resistance, we were not afraid to push more. Of course, that was a mistake because by forcing the placement, we generated ureteral lesions.
So we completely changed our procedure. We use only small access sheaths, 10/12F, because most of the endoscopes fit in the 10/12F sheath, and we never force it. If we feel any resistance, we stop immediately. We made the decision to work without or to place a double-J stent to pre-stent the ureter for 1 week. Doing it this way, it’s safe for the ureter because we don’t see any more of the lesions that we described in the past. But for me, the main and only reason to use a ureteral access sheath is to decrease the internal pressure. The second advantage is the ability to go in and out to remove fragments.
Please provide your top one or two tricks for ureteroscopy and dusting.
The holmium laser is a contact laser, with the intent being to touch targets to be efficient, but to be very efficient with dusting, you need to keep a minimal distance. Don’t touch the stone; keep a minimal distance and just move over the surface from right to left and up and down. Do this like you are painting the surface of the stone. Then, you really save time and you can produce these tiny pieces that we call dust.
A second tip is that when treating a stone into the kidney with dusting, start from the surface going to the center. You keep only one piece and you reduce the volume until the end. Into the ureter, do the opposite: Go from the center to the surface to preserve the integrity of the urothelium from possible laser damage.