Evaluating the Automated Thermedx Fluid Management System in a Ureteroscopy Model

Introduction: The Thermedx Fluid Management System (TFMS) is an automated pressurized irrigation system that allows concurrent temperature control. Developed for use in multiple surgical specialties, it provides settings specific to several endoscopic urologic procedures. The objective of this study was to critically appraise the functional characteristics and precision of the device regarding irrigation warming, pressurization, and flow during semirigid ureteroscopy. Methods: Using an in vitro model, the TFMS was assessed using the proprietary urology tubing with and without a short semirigid ureteroscopy/ureteroscope (URS) (7.4F/35 cm Wolf 425612). Pressures and temperatures were measured using continuous digital sensors (Meriam m1550-gi0015, and Taylor Digital Thermometer 9842). Stepwise increases in settings were measured with and without the ureteroscope (from 100 to 200 mm Hg), and with and without the included pressure release valve (preset for 150 mm Hg). Continuous measures (60/min) were recorded and compared with values recorded by the internal unit sensors. Results: At room temperature (18.1 degrees C), the starting irrigation temperature was 19.5 degrees C, increasing to 35.5 degrees C after 7.2 minutes at maximum settings (40 degrees C). Irrigation returned to baseline temperature after 6.7 minutes with the heater disabled. The irrigation temperature was not affected by changes in pressure settings and flow rates. The unit's display readings were 4 degrees C-6 degrees C higher than measured at the tip of the ureteroscope. Flow rates detected at the tip of the URS were 2%-8% less than the unit reported. Pressures were between 8%-17% higher using URS than that reported by the unit, and highest values were encountered when the physical safety pop-off valve was removed from the tubing. Conclusions: The TFMS provides a pressurized/warmed irrigation strategy for many endoscopic procedures. It is important to note that the system underestimates pressures at the tip of the endoscope, while overestimating the flow rates and temperatures delivered from the scope when utilizing the device.