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NEW ORLEANS, LA USA ( - In this conversation for UroToday, Dr. Khurshid Ghani, assistant professor of urology at the University of Michigan and Attending Physician at the VA Ann Arbor, Michigan Healthcare System, describes ureteroscopic stone “dusting,” an advanced technique to treat kidney stones that was developed by Dr. Ghani and colleagues. Dr. Ghani demonstrated the technique in a video at the recent American Urological Association Annual Meeting, in New Orleans, May 14-19. 2015.

Here, Dr. Ghani speaks about the ‘dusting’ technique for the readers of

UroToday: I understand that kidney stones are no less prevalent today than in the past, making them a very common medical condition.

auaDr. Ghani: The prevalence of kidney stone has nearly doubled in the past decade. About 1-in-20 adults reported a history of kidney stones 20 years ago. Today, that figure is 1-of-11 adults. Related treatment costs approach $10 billion each year, according to the Urologic Diseases of America (UDA) project.

If you look at work done by the School of Public Health at Harvard, kidney stones is a chronic disease within the top 5 of chronic diseases in the U.S. in terms of prevalence and impact.

UroToday: What accounts for this increase?

Dr. Ghani: “This is a growing problem as individuals and populations become more obese, as the incidence of type 2 diabetes and hypertension continue to increase, “These [factors] are creating an environment for kidney stone disease to flourish,” Dr. Ghani said

But today, the population at risk for kidney stones differs from in the past. “Traditionally, we thought of kidney stones as affecting younger people—in the 20s, 30s and 40s. What we are seeing in the modern era is a “bimodal” distribution of stones. Today, not just young people, but older people are developing kidney stones with greater frequency. The reason for this is that increases in obesity, type 2 diabetes, and hypertension are creating a “perfect storm” for this condition to flourish.”

UroToday: Given its prevalence, I imagine that urologists and other health care providers spend a fair proportion of their time treating patients with kidney stones…

Dr. Ghani: From the urologists’ perspective, it is probably the number one emergency that we see when we are on call: patients presenting in the emergency department with acute pain. Most stones are small enough that the patients will pass the stone without any surgical intervention. But, some patients will need operations.

A lot of stones are being picked up at the time of scans for other reasons. In the United States, from 8 to10% of CT scans of the abdomen done for other reasons will show kidney stones. A lot of these stones are asymptomatic. Depending on their size and location, patients may not need treatment.

UroToday: Could you give us some background into development of the “dusting” procedure?

Dr. Ghani: In the management of kidney stones, stones less than 2 cm in the kidney-have historically been treated with shock wave lithotripsy. Over the last 10 years, the number of shock wave lithotripsies has diminished, and more patients are undergoing minimally invasive management—flexible ureteroscopy with the holmium laser. Today, that is the dominant way of treating kidney stone, in day-case procedures that are minimally invasive.

What we have seen in the last 5 to 10 years are real advances in laser technology, delivery, and instrumentation. Companies are making very powerful 100-Watt or 120-Watt lasers that enable stones to be broken up in a different way—called “dusting.” This has attracted a lot of interest among urologists because of the technical capability that has arrived with these powerful lasers.

What we presented at the AUA from our Department of Urology at the University of Michigan is a description and our ‘tips and tricks’ on how to use the dusting technique to break down stones into small pieces—really into a fine powder. We think the advantage of the dusting technique is that you don’t need to retrieve the stones with baskets: you can break the stones into such small pieces that the patient will pass them gently and easily.

UroToday: Can you describe the “dusting” technique AUA attendees viewed in your video?

Dr. Ghani: Dusting, a very specifically defined term, means ablating stones into fine powder using particular laser settings—low-pulse energy and high frequency. Typically stones are broken down using a laser setting of 0.6 or 1 Joules (J) x 5-10 Hertz (Hz).

Dusting requires a very low pulse energy, such as 0.2 Joules (J) and very high repetition rates of 60-, 70, or 80 Hz. The advantage [of dusting] is that we are chipping the stone so rapidly that the pieces chipped off are small enough that it is almost dust coming off the stone. If you perform the technique correctly, the stone can effectively be obliterated into pieces of dust. We are hoping that this will improve outcomes for the patients, and improve stone-free rates.

UroToday: Is the dusting technique you depict in your video original?

Dr. Ghani: The technique we provide in the video is an amalgamation of tips and tricks from me and my colleagues’ [experience] in the department. The “dusting” technique has been in use over the past years by many urologists. What we have tried to do is crystallize it into some key concepts. My understanding is that this is probably the first dusting video that has been produced as a teaching tool.

In the Plenary Session at this meeting, there was a debate on dusting versus the alternative modality of treatment, known as “basketing” -- breaking the stone into pieces and then using the basket to pick all of the pieces out. But basketing technique requires a few more tools and a few more procedures to do it safely. It increases the operative time and potentially increases the risk to the kidney.

UroToday: What is clinical evidence exists for this new and novel technique?

Dr. Ghani: We provide our experience of the technique in the video [presented at the AUA meeting], as a teaching aid. We are currently looking at our own results and hope to present and publish our results soon. Another group of urologists presenting an abstract [at the AUA] found that dusting had a lower stone-free rate than basketing, but there are differences. [Overall], we need more evidence. There are important questions to answer.

UroToday: Does or could the dusting technique supplant the basketing technique?

Dr. Ghani: The take-home I have for my colleagues is that it’s not one technique or another. This is a technique to learn—how to tackle certain types of stones—how to bring the stone size nicely down. We may still need to use baskets to retrieve some pieces, but it is a new technique for the generation using high-power laser systems.

UroToday: You call your video a teaching tool. I imagine that you and your colleagues might have a plan to to expand training on the dusting technique?

Dr. Ghani: In June, we are holding a national teaching course on dusting at the University of Michigan, to teach urologists, and we have had a lot of interest. But, this is not the only way to treat kidney stones: it’s a new technique that urologists should be comfortable with.

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[AUA Abstract; Urolithiasis]

V6-12: The New Stone Age: Ureteroscopic stone “Dusting” with a 120-Watt holmium laser

Duncan R. Morhardt*, James Tracey, J. Stuart Wolf, Jr., Khurshid R. Ghani, Ann Arbor, MI

Introduction and Objectives
Techniques for laser lithotripsy during ureteroscopy (URS) have evolved with improvements in laser technology. The “Dusting” technique utilizes a high-power laser to ablate stones into fine powder. This was previously impractical due to limitations in energy settings using low-power systems. In this video we describe our experience of using a 120-Watt (W) holmium laser with dual dusting and fragmentation modes to perform flexible URS lithotripsy. We demonstrate the technique of ureteroscopic stone dusting for large renal and ureteral stones including use of ‘dancing’ and ‘chipping’ maneuvers.

We present two cases of renal stones (1.5 and 1.7 cm, respectively) and one of an impacted upper ureteral stone (1.7 cm) treated predominantly with dusting approach. Dusting is use of low pulse energy and high frequency (LoPE-HiFr) during laser lithotripsy. We used a 120-W holmium laser (Lumenis, San Jose, CA) with digital architecture that permits dual lithotripsy modes (dusting and fragmentation) and change in pulse width. A 200 micron ball-tip laser fiber was used (Flexiva, Boston Scientific, Boston, MA). Energy settings were adjusted according to stone composition, location and size, varying from 0.2-0.5 Joules (J) and rate between 30-80 Hertz (Hz).

We demonstrate effective dusting technique to treat large stones in the kidney and ureter. Our dusting strategies include use of chipping, dancing and popcorning techniques. For chipping, the laser fiber is directed to the periphery of the stone to allow small fragments to chip off. For dancing, the tip of the laser fiber is brushed back and forth across the stone surface so that it is broken down layer by layer. During dusting of renal stones if they break into medium sized fragments, we push them into dependent calyces and utilize a “popcorning” technique (1J x 15Hz). In practice, dusting is also useful for impacted ureteral stones: dusted fragments are small and do not interfere with ureteroscopic vision while appropriate dusting settings avoid inadvertent retropulsion and stone migration. We used no retrieval devices for these cases.

High-power holmium lasers have opened a new frontier in ureteroscopic laser lithotripsy by permitting a dusting approach that ablates stones into powder. Further clinical evidence is needed to better understand the efficacy of dusting and determine if outcomes are similar to conventional laser lithotripsy strategies.

Date & Time: May 17, 2015 10:30 AM-12:30 PM
Session Title: Urolithiasis
Sources of Funding: None

Presented by Khurshid R. Ghani at the American Urological Association (AUA) Annual Meeting - May 15 - 19, 2015 - New Orleans, LA USA

University of Michigan, Ann Arbor, MI USA



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