Damage of stone baskets by endourologic lithotripters: a laboratory study of 5 lithotripters and 4 basket types

Abstract

Background. In some cases, the ureteral stone is simultaneously stabilized by a stone basket when endourologic lithotripsy is performed. This stabilization can be either on purpose or by accident. By accident means that an impaction in the ureter occurs by an extraction of a stone with a basket. A stabilization on purpose means to avoid a retropulsion of the stone into the kidney during lithotripsy. At this part of the operation, stone baskets have been frequently damaged. This severing of wires can lead to ureteral trauma because of hook formation. Material and Methods. In a laboratory setting, the time and the pulse numbers were measured until breaking the wires from four different nitinol stone baskets by using five different lithotripsy devices. The endpoint was gross visibledamage to the wire and loss of electric conduction. Results. The Ho:YAG laser and the ultrasonic device were able to destroy almost all the wires. The ballistic devices and the electrohydraulic device were able to destroy thin wires. Conclusion. The operating surgeon should know the risk of damagefor every lithotripter. The Ho:YAG-laser and the ultrasonic device should be classified as dangerous for the basket wire with all adverse effects to the patient.

Figure 1

All four different basket types from left to right are as follows: (i) Dormia (Mentor Porgès), 4 helical wires (diameter 0.25 mm), 3.5 F, nitinol, (ii) Dormia (Mentor Porgès), 4 helical wires (diameter 0.18 mm), 2.5 F, nitinol, (iii) Epflex, tipless, plaited basket (wire diameter 0.127 mm), 2.5 F, nitinol, and (iv) Equadus (OptiMed), tipless basket, 4 wires (diameter 0.07 mm), 1.8 F, nitinol.

Figure 2

The schematic drawing of the experimental setup. The basket wire is fixed in a holding instrument under water. The incident angle of the lithotripter is 90°. The ohmic resistance of the basket wire is measured by an ohmmeter.

Figure 3

The EHL destroyed all tipless baskets wires in a range from 1 to 4 sec/fewer than 4 to 18 pulses. The one 3,5 Dormia basket was destroyed after 9 sec/40 pulses.

Figure 4

Destroyed (a) and intact (b) probes of the electrohydraulic device (magnification of 60).

Figure 5

Electrokinetic device (Lithorapid) with destruction of two 1.8 F tipless baskets after 16 or 26 pulses and seconds.

Figure 6

Pneumatic-ballistic device (Lithoclast) for the destruction of all 1.8 F tipless baskets, 3 of four 2.5 F tipless baskets, and one of four 2.5 F Dormia baskets. For the 1.8 F tipless baskets, the device just needed less than one second/one pulse. For the bigger wires, the device needed fewer than 5 sec/20 pulses.

Figure 7

The ultrasonic lithotripter destroyed all baskets wires with the exception of one 2.5 F tipless basket. The destruction took place from 1 to 9 sec.

Figure 8

The Hol:YAG laser destroyed all baskets wires with the exception of one 3.5 F Dormia basket. The destruction took place from 1 to 9 sec/from 1 to 52 pulses mostly after one pulse.

Figure 9

Over all the four basket types, the tipless 1.8 CH basket has the lowest resistance.

Figure 10

Over all the lithotripters, the laser and the ultrasonic device have the lowest ratio of unimpaired wires.