British Journal of Urology (1984), 56, 577-581 0 1984 British Journal of Urology

Review of Accessories for Percutaneous Renal Surgery

R . A. MILLER, S. R. PAYNE and J. E. A. WICKHAM

Department of Percutaneous Renal Surgery, Institute of Urology, London

Summary-Adequate accessory equipment is a prerequisite for successful percutaneous nephrolithotomy. The advantages of the Amplatz tube used in combination with the new sheathless nephroscopes are described. The design, action and efficiency of forceps are detailed. Triradiate rigid forceps have been shown to be superior to other types of forceps. All accessories are liable to be damaged and therefore must be regarded as semi-disposable.

Recent studies report a success rate of over 90% for percutaneous nephrolithotomy (PNL) (Clayman and Castaneda-Zuniga, 1984; Le Roy and Segura, 1984; Alken et al., 1983). Three factors have contributed to this : increasing experience (Wick- ham et af., 1983), the development of purpose- built nephroscopes (Miller and Wickham, 1983) and the evolution of sophisticated peripheral instrumentation.

Based on our clinical experience of 350 cases of PNL and experimental studies, an evaluation of peripheral instrumentation is presented.

Accessories for Endoscopic Access

Guide Wires Three types of guide wire are available : floppy J, floppy straight and Lunderqvist wire which has a rigid stem and a terminal floppy portion. The Lunderqvist wire should be reserved for dilatation of the track as it is liable to be traumatic if used as an endoscopic guide. The floppy J and straight wires are used as safety wires during endoscopy and allow access to the collecting system in the event of bleeding which obscures the view or if the track is lost.

The Amplatz Tube (W. Cook, Vance Products Ltd) This is a teflon tube which comes in a variety of sizes 24 to 26 F (Miller and Wickham, 1984a) and

Read at the 40th Annual Meeting of the British Association of Urological Surgeons in Dublin, July 1984.

may be used to secure the nephrocutaneous track. It may be inserted over a fascia1 dilator, telescopic bougie, balloon catheter or under direct vision over a nephroscope (Fig. 1). This tube will prevent extravasation, tamponade the walls of the track and prevent stones from disengaging in the track while at the same time permitting continuous flow of irrigants and stone particles. It allows nephro- scopes of different manufacture and type to be freely exchanged without fear of losing the track. The bevelled end may be rotated to expose stone particles lying under cover of its distal tip.

A rather stiffer version of this tube is made by Rusch (the Renax tube). A further modification is the addition of a side arm and proximal water seal (Rutner Cannula, Vance Products Ltd) which is supposed to channel effluxing fluids down a drainage tube, thus preventing spillage. This is of little additional advantage providing that the Amplatz tube is always used in conjunction with an appropriate wound drape (3M TUR drape).

Nephrostomy Tubes These should have a terminal opening without side holes to allow introduction over a guidewire and prevent perirenal leakage. Our preference is the Porges whistle-tipped nephrostomy tube, which may be frozen to aid insertion and is sewn to the skin to keep it in position. The tube should be the same diameter as the dilated track. The use of the new catheter slides (Wolf, Storz, Olympus) allows Foley catheters to be inserted without the use of a guide wire. Alternatively, a Vance catheter punch

578 BRITISH JOURNAL OF UROLOGY

Fig. 1 Amplatz tube being inserted over sheathless nephroscope under vision

may be used to create a terminal orifice, thus allowing introduction over a guidewire.

Stone Grasping We believe that it is preferable to extract stones intact whenever possible. Two types of instruments are available : stone baskets and triradiate grasping forceps which are flexible and may be used with flexible nephroscopes, cystoscopes and urethro- scopes, and the more powerful rigid instruments which must be used with one of the purpose-built nephroscopes which have straight instrument channels. All such devices have a tendency to break and should be regarded as semi-disposable.

Flexible Instruments The conventional Dormier basket familiar to all urologists is not ideal for percutaneous manipula- tion as it is a “side on” grasper and the stone is seen “end on”. Unlike ureteric stones, renal stones are highly mobile and therefore difficult to trap. The

pointed end and tough wires of the ordinary Dormier (Porges) can be traumatic. The Pfister- Schwartz basket (American Hospital Supplies) is more supple and therefore less traumatic but is prone to mechanical failure when kinked. Baskets with filiform tips are useful for antegrade ureteric manipulations (Vance Products). Six wire baskets offer little advantage over four wire baskets as ensnarement is more difficult. The malleable Keymed basket has very wide spaces between the wires which facilitate the trapping of stones, but unfortunately also allow them to slip out more easily.

An improvement has been the dqvelopment of 3- and 4-pronged grasping forceps (Vance Products, ACMI, Olympus, Thackray, Storz and Wolf); because of their narrow gauge (5 F) the jaws are weak and the grip exerted is rather feeble. The sharp claws are liable to become entangled in the urothelium (4-pronged more than 3-pronged) and thus cause bleeding. They should be used only under direct vision. The latest devices (ACMI,

Fig. 2 Types of forceps from left to right. Toothed alligators, contoured alligators, flat side graspers, channel triradiates.

REVIEW OF ACCESSORIES FOR PERCUTANEOUS RENAL SURGERY 579

Vance) have an outer sleeve which passes over the prongs to enhance their grip rather than relying solely on traction.

Rigid Instrumentation There are two classes of instrument: triradiate graspers and scissor action forceps (Fig. 2). These have been extensively studied, not only in our clinical series but also in the human cadaveric kidney, using a second nephroscope to examine the action of the forceps in the renal collecting system.

Triradiare Forceps (Miller and Wickham, 1984a) There are triradiate forceps which may be applied through a nephroscope (channel triradiates) (Wolf, Storz, Olympus) and optical triradiates (Wickham- Miller nephroscope, Karl Storz) (Fig. 3). For successful grasping these require powerful jaws, inturned claws and positive closure. Three-pronged graspers are easier to control than four-pronged. The optical triradiate is ideal for large stones.

Scissor Action Forceps There are three designs : alligators, contoured alligators and side flat graspers (Fig. 2). The depth of ridges in the jaws aids grasping. The contoured

alligators exert less force on the stones and are therefore suitable for softer stones. The side flat graspers are relatively feeble and cannot be recommended. The jaws should be of minimum width as they obscure the view through the nephroscope. These devices will not open fully until the hinges clear the instrument channel of the nephroscope. The location of such hinges is thus critical.

Instrument Stem The width of the stem is important to the coaxial flow of irrigants when the nephroscopes are being used without a sheath (Miller and Wickham, 1984b). The control wire within the stem is the weak point and is liable to snap irrespective of stem thickness. Thin stem forceps are more manoeuvr- able than their thicker counterparts. Fleximetallic stems are not advantageous as the distal tip is not as controllable. The teflon coat of the Olympus instruments is elegant but provides no real benefit and is significantly more expensive. A comparison of stem diameter versus instrument channel size is shown in Table 1.

A modification of the instrument stem is the introduction of a distal angle (Wickham-Miller stone forceps) (Wolf). This serves two purposes. It

Fig. 3 Wickham-Miller optical triradiate nephroscope (Karl Storz GmbH).

Table 1 Jaw Size and Stem Thickness of Alligator Forceps

Maximum jaw gap Stem diameier (mm) Nephroscope insirumeni channel size (mm)

Wolf 8962160 8282/31

Storz 10372H35 Olympus

Thackray

24 42

12.9 13 11.6

8.4 6.8 7.2

1.82 2.56 2.5

3.24 3.24 2.36

4.1

5

4

4

580 BRITISH JOURNAL OF UROLOGY

Table 2 Grasping Power of Triradiate Forceps

1.5 kg Pull on instrument Triradiate

Force (kg) needed to pull stone from forceps

0.75 cm stone 1 .OO cm stone 1 .S cm stone

Wolf 8148/02 1.7 Storz

27090 3.3 27090H 3.1

27094P Too small Storz optical triradiate

1.3

2.1 2.1

2.1

~

1 .o 1.2 1.1

1.5

Accuracy & 0.1 kg. Readings: average of 4 attempts.

Table 3 Grasping Power of Alligator Forceps

1.5 kg Pull on instrument Alligator

Force (kg) needed to disengage stone from jaws of test forceps

0.75 cm stone 1 .OO cni stone 1.5 cm stone

Wolf 8962/60 8282131

Storz 10392H35 Olympus

24 42

Thackray

0.83 3.1 0.6

0.1 1 .o 0.4

1.1 1.5 0.6

0.4 Too large Too large

Too large Too large Too large

Too large Too large Too large

Accuracy f 1 kg. All readings: average of 4 attempts.

enables the urothelial ridge which is so often seen in the front of the nephroscope to be negotiated and brings the forceps directly into the optical field of the nephroscope, thus preventing the end of the forceps sticking into the urothelium.

Handle Handles may be of the scissor type or the bow type according to individual preference. They must, however, incorporate positive closure, i.e. squeez- ing the handle closes the jaws. Sprung forceps (jaws autoclosing) are unable to generate sufficient purchase on a stone for extraction.

Grasping Element In order to evaluate the grasping efficiency of various forceps we devised a simple experiment.

Artificial stones 0.73 cm, 1 cm and 1.5 cm in diameter were made from air drying modelling dough (colorplast 8120 GBE). This substance resembles renal calculi but it is hard and will crumble if excessive force is applied to it. The stones were transfixed with a metal wire which was attached to a Salter spring balance (Fig. 4). The test forcep was applied to the “stone” and a 1.5 kg weight applied to the handle. The force registered on the spring balance in kg at the time of disengagement was noted for each device. The results are tabulated in Tables 2 and 3.

This clearly shows differences in grasping efficiency of various forceps and demonstrates the superiority of the triradiate graspers. Forces greater than 1.5 kg can in fact be applied to the handle during an actual operation. By observing

REVIEW OF ACCESSORIES FOR PERCUTANEOUS RENAL SURGERY 58 1

\

Standard Pressure 1.5ks -Applied to Stone Forcep

Fig. 4 Experimental method for determining the grip of forceps.

tl

the mode of action of the forceps in cadaveric human kidneys it became clear that when forces greater than 1.5 kg are applied the outer shell of the calculus tends to crumble and the stone thus slips out of the jaws of the forceps.

The ideal grasping device for percutaneous stone manipulation has still to be developed. Many improvements are to be anticipated as more research is performed in this area. Rigid devices will, however, probably remain superior to their flexible counterparts. Frequent breakage of forceps during operations requires that several forceps are kept on the operation trolley at all times.

References Alken, P., Gunther, R. and Thuroff, J. (1983). Percutaneous

nephrolithotomy-a routine procedure? British Journal of Urology Supplement. 1-5.

Clayman, R. and Castaneda-Zuniga, W. (1984). Nephrolitho- tomy: percutaneous removal of renal calculi. Uro/ogic Radiology, 6, 95-1 12.

Le Roy, A. J. and Sepra, J. W. (1984). Percutaneous ultrasonic lithotripsy. Urologic Radiology, 6 , 88-94.

Miller, R. A. and Wickham, J. E. A. (1983). Percutaneous nephroscopy. British Journal of Urology Supplement. 55-59.

Miller, R. A. and Wickham, J. E. A. (1984a). Optical triradiate nephroscope: a new concept in percutaneous renal surgery. Urology, 23, 20-23.

Miller, R. A. and Wickham, J. E. A. (1984b). Percutaneous nephrolithotomy : advances in equipment and endoscopic techniques. Urology, 23, 2-6.

Wickham, J. E. A., Miller, R. A. and Kellett, M. J. (1983). Percutaneous nephrolithotomy: results and cost-effective- ness. British Journal of Urorogy Supplement. 103-106.

The Authors R. A. Miller, MB, FRCS, Lecturer. S. R. Payne, MB, FRCS, Lecturer. J. E. A. Wickham, BSc, MS, FRCS, Director of Academic

Unit.

Requests for reprints to: J . E. A. Wickham, Academic Unit, Institute of Urology, 172 Shaftesbury Avenue, London WC2H 8JE.