To investigate the effects of surgical position on intrarenal pressure and intrarenal temperature during retrograde intrarenal flexible ureteroscopic lithotripsy: an in vitro model.

To investigate the changes in intrarenal pressure (IRP) and intrarenal temperature (IRT) in different surgical positions during retrograde intrarenal flexible ureteroscopic lithotripsy (RIRS) using a newly developed in vitro kidney model. Changes in IRP and IRT were tested in the conventional lithotomy position (CLP), the Trendelenburg position(TP), the Galdakao-modified supine Valdivia (GMSV) position, and the prone split-leg (PSL) position. Irrigation flow rates (FRs) of 0, 10, 20 and 30 ml/min were selected. The irrigation pressures (IPs) were 50, 100, 150, 200, 250, 300, 350 and 400 mmHg. IRP and IRT were recorded using an in vitro model under different surgical positions and combinations of FR and IP. The group with the highest IRT was the combination of TP and 0 ml/min, and the mean temperature reached 42.0 ℃. The group with the lowest IRT group was subject to the combination of PSL and 30 ml/min, and the mean temperature reached 38.0 ℃. Under the same IP, the IRP significantly differed across different surgical positions (P < 0.01). The IRP of PSL was always higher than those of the other three positions, whereas the IRP of GMSV was always lower than those of the other positions. When the IP was 400 mmHg, the pressure measured in the PSL position was 42.4 cmH2O. The mean intrarenal temperature is greater in the TP, whereas the mean intrarenal pressure is greater in the PSL. When urologists choose the above two positions during surgery, they need to pay more attention to the intrarenal temperature and intrarenal pressure to reduce intraoperative injury to patients and postoperative complications.