Bio Dilators: A Case Study

The Amplatz dilator set was developed to compensate for some of the deficiencies of the preexisting serial fascial dilators.27

In the amplatz system, an 8F angiographic catheter is initially inserted over the working guidewire. The progressively larger dilators then are inserted serially over this guidewire and catheter combination. This additional obturator stiffness greatly reduces the risk of perinephric guidewire buckling. The individual Amplatz dilators are also relatively rigid, and in combination with the stiffer working wire-catheter complex, they permit acute tract dilation through rigid perinephric scar tissue in nearly all patients. The commercially available equipment ranges up to size 30F. This is probably the most widely used

High-pressure balloons developing 15 to 30 atmospheres of pressure are available commercially, with balloon lengths up to 15 cm and diameters of 10 to12 mm. With a single balloon inflation, the entire access tract is dilated.29-30

Nephroscope : Rigid nephroscope

Rigid nephroscopes are available in diameters up to 28 Ch, allowing maximal size of working and irrigation channels. Thin nephroscopes are available for Mini-PNL (also known as Mini-perc),which uses nephroscopes ranging in diameter from 11 Ch to 18 Ch.31

Irrigation :

The irrigation fluid used should always be normal isotonic saline 0.9% unless diathermy is used.32

Ideally, the Irrigation solutions for endourology should be isotonic, non-hemolytic, nontoxic, transparent, easy to sterilize, and inexpensive. However, such a solution is not yet available. Solutions such as isotonic saline or Ringer Lactate are least harmful when absorbed into the circulation. Although sterile water has many qualities of an ideal irrigating fluid, its disadvantages are extreme hypotonicity, shock, and kidney failure. Sterile water is an inexpensive alternative to isotonic saline for irrigation during PNL. Although we did not find any difference between the two irrigation fluids with regard to the safety for smaller calculi, its safety has to be confirmed with larger studies, especially for large

Unlike ESWL; the shock wave is not focused. Therefore, the stone must be placed where the shock wave is generated . 36

The major disadvantage of EHL is its narrow margin of safety owing to the risk of damage to ureteral mucosa and ureteral perforation, the risk of perforation is greater with higher energies, such as in treatment of a hard stone. regarding advantages, EHL successfully fragments 90% of stones and it is the least expensive intracorporeal device .37

3)Ultrasonic Lithotriptors :

Ultrasound has a wide margin of safety when used appropriately. Ultrasonic waves are of an acoustic frequency beyond the range of human audibility. All current ultrasonic lithotriptors use piezoceramic crystals through which an electric current is applied to create the ultrasonic wave. The ultrasonic wave energy is transmitted along a probe and converted to vibration at the tip. Stone fragmentation occurs because of the mechanical energy of the probe and is not related to the shockwaves or heat produced. Therefore, direct contact is necessary for efficient stone fragmentation and evacuation. Probe sizes vary from 2.5F to 12F. Smaller probes often are unable to accommodate an inner lumen. Larger probes have an inner lumen that allows simultaneous suction and extraction of stone