| Objective:The purpose of this study is to research percutaneous nephrolithotomy tunnel diameter on stone clearance efficiency and intrapelvic pressure influence achieved solely by hydrodynamic effects in vitro setting,discussed the best tunnel can give consideration to stone clearance efficiency and operation safety.Methods:A watertight cylindrical cast with a caliceal void served as an in vitro model and the sealing model of the cap was formed with water tightness and air tightness.The upper part of the model was provided with a channel which can be loaded with12-30 F working sheath with different diameters.To use F8/9.8Wolf ureteroscopy and percutaneous nephrolithotomy surgery tools required for the experiment.The model connect with a Infusion pump with different perfusion pressure(10-80Kpa)and water flow used to measure the changes of the renal pelvisand hydrodynamic effects.The top of Model is 9F channels,can be loaded with pressure monitoring device for recording analog intrapelvic pressure,pressure monitoring device can collect data once per second;the application of artificial stones(diameter 2.9-3mm)test different tunnel’s stones removal efficiency,by nephrolithotomy retraction and continuous water flow perfusion,measuring the stone volume to obtain different diameter tunnel stones clearance efficiency.Each group of experiments were carried out 3 times,data input into the computer in real time,using SPSS 19 software for statistics analysis,P<0.05 was statistically significant.The observation indexes include perfusion pressure,perfusion flow rate,tunnel diameter,stone removal rate,intrapelvic pressure.Results:The linear regression analysis showed that there was a positive correlation between the perfusion pressure and the internal pressure,the greater the perfusion pressure,the higher the renal pelvic pressure.When the perfusion pressure was 80 Kpa,the mean intrapelvic pressure of the 12-30 F was 75.67±7.23,51.33±3.21,36.00±4,28.67±3.05,22.00±2.65,17.33±1.53,13.00±1,9.33±1.53,9.67±0.58,8.67±0.58.18 F and below internal pressure close to or more than the safety range of30 mmhg,more than 18 F are in a safe range;12F group mean intrapelvic pressure higher than other groups(P <0.05),14 F group of average intrapelvic pressure is higher than above 14 F group(P <0.05).18 F group of average intrapelvic pressure is higher than above 18 F group(P <0.05),20 F group average intrapelvic pressure is higher than 24,26,28,30 F group(P <0.05),22 F group average intrapelvic pressure is higher than 26,28,30 F group(P <0.05),there was no significant difference between the 20 and 22 F group(P > 0.05),there was no significant difference between the 24,26,28,30 F group(P >0.05).When the perfusion pressure 80 Kpa,the stone clearance rate of 16~30F channel was 6.5±0.4,8.8±0.8,9.3±1.1,8.5±0.2,7.1±0.5,7.2± 0.5,6.7 ± 0.7,6.5 ± 0.7ml/min.18,20 and 22F group passive stone cleaning efficiency were fatest than other channels(P <0.05),There were the was no statistically significant difference among them(P >0.05).Conclusion:1.Linear regression analysis showed that there was a positive correlation between the perfusion pressure and the internal pressure,the greater the perfusion pressure,the higher the renal pelvic pressure.2.When using F8/9.8 Wolf ureteroscopy,the perfusion pressure of 80 Kpa,20~30F tunnel of intrapelvic pressure was always lower than the safe range of 30 mmHg.18F and below mean intrapelvic pressure is higher than 30 mmHg.When there is enough space between the ureteroscope and the working tunnel,the high perfusion pressure does not cause the high intrapelvic pressure.3.The removal efficiency of the stone was not increased with the increase of the tunnel diameter,and the efficiency of 18~22F channel was the fatest than that of other tunnels(P <0.05).4.When the perfusion pressure reaches 80 Kpa,the intrapelvic pressure of 20 ~ 22 F channel is safe,and it can be used as the first choice for MPCNL. |
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