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ESWL machine at Washington University much later. With that in mind, I'm very much a huge fan of ESWL. What we've learned over the years is to apply it to the right patient and to the right stone. Basically, what we've learned is the ideal situation for ESWL is if the stone is 1 cm or less, is in the renal pelvis or upper/ middle calyces, has Hounsfield units under 1000 and the patient’s skin to stone distance is 10 cm or less. With those criteria, the success rate of ESWL is in 90% range. As those parameters are not met, the results decrease accordingly.
By the same token, our results currently with ureteroscopy are pretty much terrible. You're looking at CT based true (i.e., no fragments remaining) stone- free rates of 60% to 70% and that is in the very best of hands, as independently reported by Peggy Pearle and by Jim Lingeman. We need to be very honest with ourselves and others in defining the results of any stone treatment. Stone free can only mean that on the CT scan there are no stones. It doesn't mean that you have less than or equal to 4 mm fragments in the patient's kidney. That's ridiculous. You're either stone-free or you're not. The Journal of Endourology has taken the bold step of only accepting manuscripts in which the stone free status is based solely on CT scans with 2-3mm cuts and then established grades of success with Grade A being no stones seen on CT scan, Grade B </= 2mm fragments, and Grade C </= 4mm fragments. How are we going to make our success rate with ureteroscopy better? You want to give your patient a treatment that you think is going to really remove the entire stone. Certainly, the patient didn't come to you for partial stone removal? So, we have a long way to go. Fortunately advances in aspiration ureteroscopy as pioneered by Calyxo and as are being developed in our laboratory over the past several years and the advent of burst wave office shock wave lithotripsy hold so much promise for improving our stone free results.
T.S.: New laser devices, flexible ureteroscopes, access sheaths and baskets with emerging technology have entered the market of ureteroscopic stone disease management. Do you believe that PCNL is going to belong in the past in the close future?
Prof. Ralph V. Clayman: Not too long ago, I gave a lecture entitled: "Kill Perc". That sums up where I
think we're going, or where I hope we're going. The good Lord gave us a natural access to the kidney. True, as it currently stands it is a narrow "one lane highway". Back in the 1970’s that natural path was just not big enough and thus we went off creating our own broad road to the kidney, cutting through the skin of the flank and blasting through one of the most vascular organs in the entire body, to get to the stone. At that time, PCNL was a great idea and it indeed, killed the far more morbid open incisional approach to removing renal calculi.
Fast forward 50 years and now I think ureteroscopy should retire PCNL, eventually. What do we need? We need safer placement of access sheaths, maybe bigger access sheaths, better ureteroscopes, more efficient lasers. Do I think that's going to happen? Yes. Do I have any data for that? Yes, as we have shown some ureters can accommodate an 18 French access sheath were it available and over half of ureters can accommodate a 16 French access sheath. Further, as proof of the potential for aspiration endoscopy, we have been able to pass a 16.67 French Karl Storz flexible cystoscope, that has built in aspiration, in several women with stone larger than 2 cm. We've been able to irrigate, aspirate and laser these stones and reduce the stone burden by 90% in all of these cases, with some of them becoming stone free. Good but not perfect, still, it’s a proof of concept. What I see eventually coming, in this day and age of disposable flexible ureteroscopes, with the LED for the light source being so cheap and the CMOS chip for visualization also being so inexpensive, is a day where we will do "bespoke surgery". That means that, we will have a host of ureteroscopes from which to choose, and based on what that particular patient's ureter dilates to at <8N, we will choose that size ureteroscope. If it's a woman, it'll be 45 cm long and if it's a male, it'll be 65 cm long. Without an access sheath, we will pass that ureteroscope up the ureter once and then proceed to irrigate, laser and aspirate all simultaneously until there is not a single fragment remaining in the kidney. When we're done, if that ureteroscope went up at less than 4 newtons and the ureter looks fine, we won't even leave a stent. So, my goal eventually is to see a day where we will have what I call "one pass ureteroscopy", with no baskets, no access sheaths, no stents and 100% stone-free patients. That's the goal. We are not there yet but we are well on our way.
Tεύχος 31 | Σεπτέμβριος - Οκτώβριος 2024
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