At a lithotripsy power of 10 W, with irrigation speeds of 10 ml/min, 15 ml/min, 20 ml/min, 25 ml/min, and 30 ml/min, the intrarenal temperature reached a steady state with steady-state temperatures of 38.6 °C, 35 °C, 33.1 °C, 31.7 °C, and 30.7 °C, respectively, none of which exceeded the safety threshold (Fig. 1). At a lithotripsy power of 15 W, the intrarenal temperature continued to rise with an irrigation speed of 10 ml/min. However, at irrigation speeds of 15 ml/min, 20 ml/min, 25 ml/min, and 30 ml/min, the intrarenal temperature reached a steady state with steady-state temperatures of 38.4 °C, 35.9 °C, 34.7 °C, and 34.4 °C, respectively, none of which exceeded the safety threshold (Fig. 2). At a lithotripsy power of 20 W, the intrarenal temperature continued to rise with irrigation speeds of 10 ml/min and 15 ml/min. However, at irrigation speeds of 20 ml/min, 25 ml/min, and 30 ml/min, the intrarenal temperature reached a steady state with steady-state temperatures of 38.7 °C, 36.3 °C, and 34.2 °C, respectively, none of which exceeded the safety threshold (Fig. 3). At a lithotripsy power of 25 W, the intrarenal temperature continued to rise with irrigation speeds of 10 ml/min, 15 ml/min, and 20 ml/min. However, at irrigation speeds of 25 ml/min and 30 ml/min, the intrarenal temperature reached a steady state with steady-state temperatures of 38.3 °C and 35.7 °C, respectively, neither of which exceeded the safety threshold (Fig. 4). At a lithotripsy power of 30 W, the intrarenal temperature continued to rise with irrigation speeds of 10 ml/min, 15 ml/min, 20 ml/min, and 25 ml/min. However, at an irrigation speed of 30 ml/min, the intrarenal temperature reached a steady state with a steady-state temperature of 37.5 °C, which did not exceed the safety threshold (Fig. 5). At different irrigation speeds, the intrarenal pelvic/calyceal pressure did not exceed 30mmH2O (Table 1).

Renal temperature at each irrigation speed at 10 W of gravel power

Renal temperature at each irrigation speed at 15 W of gravel power

Renal temperature at each irrigation speed at 20 W of gravel power

Renal temperature at each irrigation speed at 25 W of gravel power

Renal temperature at each irrigation speed at 30 W of gravel power

When the On-Duty Cycle (ODC) is maintained below 60%, the steady-state intrarenal temperature tends to stabilize after reaching a certain value and does not further increase with the extension of time. In contrast, when the ODC exceeds 70%, the intrarenal temperature during the subsequent steady-state continues to rise over time (Fig. 6). With the increase of ODC, the highest intrarenal temperature shows a significant upward trend: ODC50%: 40.0 ± 0.52 °C; ODC 60%: 41.6 ± 0.38 °C; ODC 70%: 43.4 ± 0.48 °C; ODC 80%: 44.8 ± 0.73 °C; ODC 90%: 46.7 ± 0.54 °C (Table 2). When the ODC ratios are 70%, 80%, 90%, and 100%, respectively, the time for intrarenal temperature to reach the safety threshold temperature is 56.0 ± 1.0s, 51.8 ± 1.48s, 32.0 ± 1.58s, and 20.6 ± 1.14s, respectively (Table 3).

Curve of renal temperature during the working cycle (ODC) of different proportions (laser power set to 20 W, irrigation speed is 10 ml/min)