Automatic Irrigation System With Fiber-Optic Pressure Sensor for Real-Time Intrarenal Pressure Control During Instrument Insertion and Laser Irradiation

Precise control of intrarenal pressure (IPP) during flexible ureteroscopy is critical for preventing postoperative complications linked to pyelovenous or pyelosinus reflux. We developed an automatic irrigation system incorporating an ultraminiature fiber-optic pressure sensor for real-time IPP monitoring and control. The sensor, with an outer diameter of 0.125 mm, positioned 2 mm inside the ureteroscope tip, provides high-resolution pressure measurements (±~0.75 mmHg) with temperature compensation. A proportional-integral-derivative controller automatically adjusts the speed of a roller pump to maintain target IPP levels based on real-time sensor feedback. The system was evaluated using a porcine kidney model during insertion/removal of surgical instruments (272-μm laser fiber and 1.3-Fr basket forceps) and Ho:YAG laser lithotripsy procedures. Manual control showed delayed responses to pressure changes during both insertion and removal, whereas the automated control demonstrated a rapid return to a stable pressure. During 10-W Ho:YAG laser irradiation, constant pump speed operation led to progressive IPP baseline elevation with repeated firing, while the automated control prevented cumulative pressure buildup and maintained a stable baseline pressure. The fiber-optic sensor demonstrated superior spatial and temporal resolution compared to sheath-based pressure monitoring systems. The automated irrigation system effectively reduced IPP fluctuations during critical surgical operations. This approach represents a significant advancement in endourological safety and precision, and offers the potential for widespread clinical implementation in flexible ureteroscopy procedures.