1) Ho:YAG “Moses effect”
Recently, Holmium: yttrium-aluminum-garnet (Ho:YAG) lasers acquired new pulse modulation capabilities that improve efficiency. With first and second-generation Ho:YAG lasers, a pulse of energy created a short-lived bubble, and most of the energy was absorbed by water within two millimeters of the laser fiber. With high-frequency third-generation Ho:YAG lasers that feature what’s called the “Moses effect,” one pulse creates the familiar bubble, and the next pulse travels through the bubble to the stone without being absorbed by the water. Energy transmission to the stone is much higher, even at greater distances.
The low energy/high-frequency approach allows surgeons to adjust the fragment size and dust stones very easily. There is also much less stone retropulsion, so after laser energy hits the stone, surgeons don’t need to chase it, adding time, risk, and cost to surgery. Lumenis Ltd. was the first company to offer this advance in 2017. Their patented solution was proven to increase stone ablation, reduce retropulsion, and decrease procedure time.2 Recently, Quanta Laser System began offering the Vapor Tunnel™, and Dornier MedTech released an Advanced Mode™. However, clinical and bench data is lacking with regards to their mechanisms of action and efficacy at this point.
2) Thulium fiber laser
In a thulium fiber laser (TFL) system, a diode laser source transfers energy to a thulium-doped silica fiber and then to the same type of low-hydroxyl silica fibers that surgeons commonly use with Ho:YAG lasers. TFL can reach pulse frequencies of up to 2,200 pulses/second.
TFL is an emerging laser technology, so little data is available on its safety and efficacy for kidney stone management. It can attain very long pulse durations, which theoretically may aid in stone dusting, but the data to support that does not yet exist. We do not yet know about the technology’s ability to fragment hard stones using high power and low frequency. TFL might permit the use of fibers as small as 50μm, but initial benchtop data was using only fibers 200μm and above. Its wavelength of 1,940μm is more highly absorbed in water, which may impact its efficiency. IPG Photonics has marketed a TFL system abroad, and Olympus has filed FDA 510k premarket notification to distribute it in North America.
3) Novel mechanical lithotrites
Recent benchtop and clinical studies have shown that new mechanical lithotrites enhance the ability to quickly break and remove large stone volumes during percutaneous nephrolithotomy (PCNL). Previous lithotrites have incorporated both ultrasonic and pneumatic energy generation into the handpiece, often at the expense of suction capability. The new Swiss LithoClast® Trilogy device uses a novel electromagnetic mechanism to combine all three modalities into the handpiece. Benchtop and clinical data have shown the Trilogy to be highly efficient at both stone ablation and suction evacuation of the fragments. The Trilogy was developed by EMS and is distributed in North America by Boston Scientific.
4) New mini-PCNL instruments
The trend toward smaller instruments has been a long one in urology. In recent years, “mini-PCNL,” which promises to cut standard 30Fr PCNL tract sizes in half, has been a popular discussion.
Questions have surrounded how companies will make effective, efficient instruments that fit the smaller sheath and scope size. Cutting-edge development is now focused on smaller probes for mini scopes, as well as lasers that can effectively dust stones because the suction is often not possible at this size. As manufacturers work to catch up with the trend toward miniaturization, new probes for mini-PCNL that are just 1.83mm and 1.5mm have recently been released by Olympus and EMS for their ShockPulse-SE and Trilogy devices, respectively. We can expect device manufacturers to continue to develop and refine mini-PCNL instruments in the future as these procedures continue to increase in popularity.
Written by: Russell S. Terry, MD, Duke Comprehensive Kidney Stone Center, Duke University Medical Center, Durham, North Carolina
- Terry, Russell S., Patrick S. Whelan, and Michael E. Lipkin. "New devices for kidney stone management." Current Opinion in Urology 30, no. 2 (2020): 144-148.
- Ibrahim, Ahmed, Mostafa M. Elhilali, Nader Fahmy, Serge Carrier, and Sero Andonian. "Double-Blinded Prospective Randomized Clinical Trial Comparing Regular and Moses Modes of Holmium Laser Lithotripsy." Journal of Endourology (2020).