Clinical Trial Evaluating the Efficiency of Holmium Laser Settings on Urinary Stones

The primary objective of this study is to compare the time to acceptable stone fragmentation during clinical use of the holmium laser when using energy settings 0.2J vs 0.8J. The hypothesis is that holmium laser energy settings 0.8J will require less time than lower energy settings 0.2J for fragmenting urinary stones. The clinical practice is to treat urinary stones until the stone is reduced to fragments ≤ 2 mm in size. This is determined by using the laser fiber which is 273 microns to visually estimate the size of the resultant fragments as described by Patel et al, J Endo 2014. Investigators will standardize the effect of stone size by creating a ratio of stone size to treatment time. In this study, the frequency is set at 15Hz. Thus, the study contains two arms: 0.2J&15Hz, and 0.8J&15Hz. Patients will be randomized into the two groups by the ratio of 1:1.

The only interventions imposed on subjects as a result of this study are (1) pre-procedural randomization to laser lithotripsy with either 0.2J or 0.8J energy setting, and (2) the use of patient information in describing results. All the other activities are part of the routine clinical practice in the department. Participation in the study will not alter the patients' preoperative, or postoperative care. During surgery, patients' stones will be treated in accordance with the routine clinical practice of fragmenting stones into small pieces (<2 mm). All patients enrolled will undergo routine post-operative follow up including clinic appointments and imaging evaluation. Any complications will be recorded, reported, and treated appropriately. A fixed frequency will be used (15Hz). Thus, the study contains two arms: 0.2J&15Hz, and 0.8J&15Hz. Patients will be randomized into the two groups by the ratio of 1:1. A total of 1 clinic visit (i.e., the stone surgery, approximately 5-6 hours, depending on the duration of the surgery) is needed for this study. The study procedures are: A study team member who is affiliated with the patient's clinical care (e.g., the surgeon) will initially approach the patients who are scheduled laser lithotripsy treatment of urinary stones. (i.e. informed that there's a research study they may be eligible for, and asked if they want to learn more about it). If the patient is interested in the study, a member of the research team will approach him/her for enrollment. Once the consent form is obtained, patients' medical background will be reviewed for inclusion/exclusion criteria. Patients who meet the inclusion criteria will be included in the study; patients who do not meet the inclusion criteria will be excluded. Patients will be randomized to either 0.2J&15Hz or 0.8J&15Hz (randomization ratio 1:1) group. Patients will undergo stone surgeries with the laser setting that they are randomized to. The patient's stone(s) will be treated in accordance with the routine clinical practice of fragmenting stone into small pieces (≤ 2mm). The faculty surgeon (i.e., Dr. Nakada) will perform all surgeries. Fragmentation time as well as other information (total surgery time, complications, stone information, and number of stones treated) is collected. After surgery, the patients will then continue on normal postoperative pathway. Postoperative complications will be collected.

Treatment of urolithiasis is commonly done using the holmium:YAG laser as this has been shown to be a safe and effective method of treating a wide variety of stones and is currently considered the standard of care (AUA Guideline Panel on the Surgical Management of Stones)

Inclusion Criteria: Patients at least 18 years of age Patients with urinary stones who require endoscopic treatment Exclusion Criteria: Patients < 18 years of age Pregnant patients Pre-menopausal females who have not been on approved birth control for at least 1 month pre-operatively Patients with stones known to be refractory to treatment with the holmium laser