The Thermal Effects Of Holmium Laser Lithotripsy In Urinary Calculus In An Vitro Model

ObjectiveHolmium laser lithotripsy is the main method for the treatment of urinary calculi.The purpose of this study was to investigate the factors influencing the thermal effects of holmium laser lithotripsy of urinary calculi and provide guidance for useing holmium laser in operation.MethodsWe constructed a vitro model of holmium laser thermal effects.And in 37 ? constant temperature tank,at room temperature(22 ?,temperature humidity 60%),holmium connected laser fiber and placed in an holmium laser thermal effects vitro model.We studied the affected factors about thermal effects of holmium laser lithotripsy: different power and energy patterns(1.0 J x 10 hz,0.5 J x 20 hz,1.0 J x 20 hz,2.0 J x 20 hz),the perfusion fluid temperature(20 ? physiological saline,37 ? physiological saline),the infusion speed(0 ml/min,10 ml/min,16 ml/min),optical fiber diameter(200?m,365?m,550?m dahua holmium laser optical fiber),gravel model(gravel group and empty group).The holmium laser stimulated 120 s,during which the electronic thermometer measured and recorded temperature inside and outside the model every 1 second.In each experiment,professional laser pruning scissors were used to cut 5 mm off the fiber tip to ensure the holmium laser energy transmission efficiency.After each experiment,there was an interval of 5 minutes,so that the temperature of each part of the experimental device returned to normal.Each group of experiments were repeated 3 times,and the average value of the three groups of experimental data was taken as the final experimental result.ResultsHolmium laser can produce obvious thermal effects.As the test begins,the temperature in the test tube increased rapidly,at around the 40 s,the temperature reached the plateau stage,and then the temperature tend to be stable.In whole experimental process,the temperature outside the u-tube fluctuated within 0-0.5 ?,and had no obvious change.With the increase of power,fiber diameter and infusion temperature,the thermal effects of holmium laser increased,and the difference between groups was statistically significan(P<0.05).The thermal effects of high-frequency low-energy mode were higher than that of high-energy low-frequency mode,and the difference between groups was statistically significant(P<0.05).With the increase of the infusion speed,the holmium laser thermal effects decreased,and the difference among all groups was statistically significant(P<0.05).The temperature of the lithotripsy model was lower than that of the empty excitation model,but the difference between the two groups was not statistically significant(P>0.05).With the optimal scale regression analysis of power and energy mode,perfusion velocity,perfusion liquid temperature and fiber diameter,the result showed that the model had a large degree of fitting,and the adjusted R square was 89%,F=228.857,and the difference was statistically significant(P<0.001).Further analysis showed that power and energy mode,infusion speed,perfusion temperature and fiber diameter were the influencing factors of holmium laser thermal effects.ConclusionHolmium laser can produce obvious thermal effects.The power and energy of holmium laser,perfusion rate,perfusion temperature and fiber diameter are influencing factors of the thermal effect of holmium laser.Reducing the power of holmium laser,high-energy low-frequency mode,increasing the infusion speed,using fiber with small diameter and choosing normal temperature perfusion solution are all helpful to reduce the thermal effects of holmium laser.The rate of holmium laser infusion is the primary factor affecting the thermal effect of holmium laser.It is safe to use holmium laser with adequate perfusion.