Session: PD45: Stone Disease Surgical Therapy (including ESWL) IV
PD45-03: Factors affecting holmium laser inefficiency: Comparison of laryngeal mask airway and endotracheal tube use during flexible ureteroscopy for renal stones
Introduction: Flexible ureteroscopy with laser lithotripsy (fURSL) has become the standard treatment option for many types of kidney stones, however, many inefficiencies exist that can potentially increase operative time and therefore risk of complications. During surgery, respiratory motion causes clinically significant movement of the kidneys which can defocus laser energy from the stone and require the surgeon to halt laser firing. This can be influenced by factors such as BMI and airway securement by endotracheal tube (ETT) or laryngeal mask airway (LMA). Newer Lumenis Pulse™ 120H holmium lasers provide access to previously unavailable intraoperative data including timestamps and duration of pauses between laser activation. We sought to utilize this data to calculate a “lasing inefficiency” percentage for each case to objectively identify surgical and anthropometric factors associated with decreased operative efficiency. Methods: A total of 48 intraoperative reports and patient data sets were analyzed from an ongoing laser lithotripsy clinical trial which includes metrics such as age, sex, race, BMI, and kidney stone characteristics. Ureteroscopy in each case was performed by a fellowship-trained, attending endourologist. Lasing activation start times and duration were used to calculate pauses between each laser firing. Pauses longer than 30 seconds long were excluded to account for navigation to a different site or change of instrumentation. The total lasing pause time was divided by the total lasing duration to yield a “lasing inefficiency” percentage for every case. Both multivariate and univariate analysis was performed to compare lasing inefficiency to patient demographics, anesthesia administration, and stone burden. Results: Patients who received an LMA had significantly higher lasing inefficiency (26.5%) compared to those who received ETT intubation (20.7%) in the univariate analysis (p < 0.05) as well as in the multivariate model. There were no significant differences in lasing inefficiency for the other study variables. Though BMI was not found to be significantly correlated with lasing inefficiency, we noted that high patient BMI was significantly correlated with use of ETT over LMA. Conclusions: Our data supports the use of ETT over LMA to reduce lasing inefficiency when using Holmium lasers in fURSL. However, it remains one consideration among many when choosing between utilizing an LMA or ETT. SOURCE OF Funding: This project was supported by the Endourological Society 2022 Summer Student Scholarship.
