MOSES technology was developed by Lumenis Ltd to maximize the lithotripsy potential of high powered lasers. Typically, a holmium laser unit is used to treat kidney a ureteral stones that are too large to remove en block. Laser lithotripsy allows for a large stone to be partitioned into smaller fragments that can be removed with an endoscopic basket device. Holmium technology has existed for more than 20 years, however, low total power (40 watt) and minimal modulations (Joules and Hertz) of the laser energy by the laser units limited the capacity to improve lithotripsy efficiency.

With the advent of high power (120 watt) lasers with 4 laser cores and developments in software to modulate the laser energy, many more options have emerged for laser lithotripsy of kidney and ureteral stones. At Indiana University Health Physicians Urology, the laser units used for nephrolithotripsy are engineered and produced by Lumenis Ltd. These units are fitted with MOSES technology. Standard laser lithotripsy or MOSES laser lithotripsy can be performed using the same unit and during the same case by simple turning MOSES on or off on the laser touch screen (image 1). MOSES is propriety technology that is software based modulation of the laser energy delivered from the holmium::yag laser source. The software changes the pulsed laser to have two peaks of energy - one to displace the water in front of the stone and the second to deliver the laser energy to the stone. Holmium laser energy dissipates quickly in water, so the displacement of water in front of the stone means more energy is delivered to the stone. With more energy delivery, stone fragmentation is expected to occur more rapidly.

When treating kidney or ureteral stones, there are two distinct surgical approaches. One technique is to use laser lithotripsy to break a stone into tiny pieces called dusting. Dusting technique attempts to turn a stone into a slurry of 2mm or less stone fragments that the patient can pass spontaneously. There are some urologist who promote the use of MOSES technology to improve the efficiency of the dusting technique and reduce operative time. Another approach to endoscopic stone surgery is to laser the stone into fragments to remove with a basket. There is far less laser energy used in this process, however, hard stones and larger stones can take time to fragment. Based on the dusting ureteroscopy data, MOSES technology could still improve fragmentation efficiency and reduce overall operative time.

This is a blinded study. The research coordinator will present to the OR prior to the surgeon to meet with OR staff. At this time, the coordinator will inform the OR staff which group the participant has been randomly assigned. OR staff will be educated to set the laser as instructed by the surgeon but not share whether the MOSES laser lithotripsy is being used. Surgeons will not be aware of the group assignment. The surgeons are only able to adjust the laser energy settings between 0.4-1.0 joules and 4-15 hertz. To control for stone fragment size, surgeons will have to use an 13 french ureteral access sheath independent of ureteral diameter. The MOSES setting is turned on with a touch pad attached to the laser unit. Once the surgeon is ready to laser fragment the stone, the laser will be activated and with the surgeon provided laser energy settings. The laser technician/nurse will follow randomization and add or remove the MOSES option. The surgeons will not be informed if using standard laser or MOSES augmented laser technology. At the conclusion of laser fragmentation, stone basket extraction will occur and once all fragments are removed, the patient will have a ureteral stent placed, awoken, extubated and transferred to the post anesthesia recovery unit. Objective data about laser settings, utilization time and total energy will be obtained at the conclusion of the case. Additionally, the circulating team will record the total OR time. Other variables of interest include blood loss, blood transfusion requirements and complications (utilizing Clavien-Dindo classification) with an expected rate of approximately 1-2%. Subjective grading of stone movement during laser fragmentation as well as stone migration will be recorded.

In addition to the intraoperative variables mentioned above, clinical information including stone size, location, and stone analysis will be recorded.