Alleviating the Cause of Bleeding
The kidney is a highly vascular organ. A perfect access, along with minimum dilatation, can result in a near-bloodless procedure, as well as clarity of vision and excellent stone disintegration. We looked at the factors responsible for bleeding and found that the size of the surgical tract used to access the kidney was one of the common factors in bleeding, perforation, calyceal rupture, infundibular tear, persistent leaking, pain, and nephron loss. Our study showed that if dilatation is less than 22F, less bleeding and blood transfusion occurred, compared to procedures with larger 30F dilation.1-2
In an effort to address this problem, we began in 1997 to use a small Amplatz sheath (16F) with a 14F nephroscope. At that time, the energy source was the LithoClast pneumatic lithotriptor (EMS, Switz). Around 2000, Karl Storz came out with a miniperc sheath with a 12F nephroscope, which became available in India after few years. We found the perfect answer to reduce bleeding, the most important morbidity of PCNL. With less bleeding, we were able to start performing the “tubeless” miniperc procedure (without a nephrostomy tube), reducing the hospital stay.
In 2013, I developed the micro PCNL procedure. I use a 16-gauge needle with a 0.9 mm nephroscope and 200 micron laser fibers to disintegrate the stone, without the need for dilatation. There is no bleeding. The procedure is useful for small stones (less than 1 cm), lower calyceal stones, residual stones, or small stones in children. Next, physicians developed minimally invasive PCNL (MIP) extra small (XS) using sheaths from 8.5 to 9.5F, and MIP small (S) using 11 to 12F sheaths, both with a 7.5F nephroscope. Each advance in instrumentation has allowed us to tailor treatment to our patients according to stone size and reduce complications of PCNL.
Refining Mini PCNL Laser Technologies
Although the miniaturization of instruments garners much of the focus in the miniperc discussion, that miniaturization would not have made so great an impact without advances in the energy used to fragment stones. Miniaturization certainly was not possible using ultrasound energy, which required a large channel scope, nor was it possible with the early lasers used for kidney stone fragmentation, such as the pulse dye laser my colleagues and I began using to fragment stones nearly 30 years ago. That type of laser was costly and not very effective, and miniperc with the laser was more time-consuming than standard PCNL.3
Over next 10 to 15 years, holmium laser technology gained use for stone fragmentation and grew more effective as fibers of different sizes became available. With the development of fine laser fibers that are only microns thick, the surgical track for miniperc could be smaller than ever before. We reduced complications, including bleeding, without compromising success.
Over time, new advances in holmium lasers and fibers have enabled us to continue refining the miniperc technique. The MOSES technology (Lumenis) overcomes several limitations of past lasers. For example, because a laser loses energy when transmitted through water, we need to keep a laser fiber tip in contact with the stone, but because the MOSES technology transmits energy through a bubble, it is effective up to several millimeters from the stone without losing power. This requires less time than touching each stone. The MOSES Pulse 120H (Lumenis) is a powerful machine, which enables us to “dust” some stones for easy removal. When using a flexible ureteroscope with the flexible fibers, we can also negotiate curves without damaging the inner channel.
Experiencing the Mini PCNL Procedure
Stone volume still determines which kidney stone procedure is best for our patients. Over the years, changes in technology have made it possible for us to remove stones earlier. For the last 10 years in my practice, 63.8% of the stones we removed by PCNL were less than 2 cm, 23.7% were 2 to 3 cm, and 11.7% were staghorn. For staghorn stones or large stones with a dilated system, standard PCNL is required. When stones are smaller than 2 to 3 cm, miniperc is ideal. We use micro PCNL, retrograde intrarenal surgery, or extracorporeal shock wave lithotripsy for stones less than 1 cm.
Last year, we performed 163 (42.5%) standard PCNL procedures, 219 (57%) miniperc, and 2 (0.5 %) micro PCNL. When we use one of the miniperc procedures, our patients have less bleeding compared to standard PCNL, as well as considerably reduced pain and analgesic use and shorter hospitalization, particularly for tubeless surgery.4
Miniperc is now part of our armamentarium. Stones come in different forms and conditions, and we assess them and use the appropriate method for removal. The more methods one masters, the more capable we are to deal with multiple situations. It is also important that less invasive techniques support earlier surgical intervention, because stone disease is recurrent, and neglecting it can destroy a kidney. With increasing expertise in miniperc, we are able to utilize the same approach in all possible clinical stone scenarios, with different miniperc instruments and with flexible ureteroscopy, but with the same laser fiber. Our goal is complete clearance with minimal morbidity and less hospital time.
Written by: Mahesh Desai, MS, FRCS, FRCS, FACS, Managing Trustee at Muljibhai Patel Urological Hospital in Nadiad, Gujarat, India. He is a past president of the Societé Internationale d'Urologie and past president of World Endourological Society.
References:
1. Gune R, Ridhorkar VR, Sabnis R, et al. Factors affecting blood loss during percutaneous nephrolithotomy. Indian Journal of Urology. 1998 July;14(1):9-12.
2. Kukreja R, Desai M, Patel S, Bapat S, Desai MR. Factors affecting blood loss during percutaneous nephrolithotomy: prospective study. J Endourol. 2004 Oct;18(8):715-22.
3. Desai M, Singh A, Bhattu A, Ganpule A, Mishra SK, Sabnis RB. Laserclast: Laser with suction as an energy source in mini PCNL. American Urology Association Annual Meeting, May 15-19, 2015, New Orleans, La.
4. Mishra S, Sharma R, Garg C, Kurien A, Sabnis R, Desai M. Prospective comparative study of miniperc and standard PNL for treatment of 1 to 2 cm size renal stone. BJU Int. 2011 Sep;108(6):896-9; discussion 899-900.