CLINICAL AND COMMUNITY STUDIES 0
ETUDES CLINIQUES ET COMMUNAUTAIRES
Laser lithotripsy in the treatment of ureteral calculi Kostantinos E. Psihramis, MD, CM, FRCSC; Martin B. Buckspan, MD, FRCSC, FACS We examined the effectiveness of laser lithotripsy with a flash-lamp-pumped tunable dye laser in the treatment of ureteral calculi that were too large for direct extraction and that could not be treated with or had not responded to extracorporeal shock-wave lithotripsy (ESWL) or forms of ureteroscopic lithotripsy other than laser lithotripsy. In 20 (74%) of the 27 patients the laser alone successfully fragmented the calculi into pieces small enough to pass spontaneously or to be easily extracted with a basket. In five (19%) laser lithotripsy was partially successful: another procedure (ESWL in three and fragment extraction with a basket in two) was needed. In two patients (7%) the stones could not be fragmented with the laser, and either ESWL or percutaneous antegrade extraction was performed. At follow-up 3 months after treatment there was no sign of stone fragments in 26 (96%) of the patients. We believe that laser lithotripsy is a safe and effective method of ureteral stone fragmentation.
Nous determinons l'efflcacite de la lithotripsie au laser accordable a colorant pompe par une lampe-eclair dans le traitement des calculs ureteraux trop gros pour etre extraits d'emblee et qui ne se pretaient pas ou ont resiste soit a la lithotripsie extracorporelle par ondes de choc (LEOC), soit a une forme de lithotripsie endoscopique autre que le laser. Parmi 27 malades, chez 20 (74%) les calculs sont suffisamment fragmentes par le laser pour passer spontanement ou du moins etre aisement extraits seance tenante au panier. Chez cinq malades (19%) le laser donne un succes partiel: il faut recourir par la suite soit a la LEOC (trois fois), soit a l'extraction de fragments au panier (deux fois). Pour les deux malades (7%) dont les calculs resistent au laser on a recours a la LEOC ou a l'extraction proximale percutanee. Au bout de 3 mois 26 des malades (96%) ne donnent aucun signe de fragments residuels. D'apres nous la lithotripsie au laser est efficace et securitaire pour la fragmentation des calculs ureteraux.
Urinary stone disease affects about 3% of North Americans. In the past its treatment usually required some form of open surgical intervention. But over the last decade a number of innovations have allowed the fragmentation and removal of urinary calculi without open surgery. The first, percutaneous ultrasonic lithotripsy, was quickly followed by extracorporeal shock-wave lithotripsy (ESWL), which has rapidly become the treatment of choice for most renal and upper ureteral calculi since its introduction in 1980.1.2 About 20% of all ureteral calculi do not pass spontaneously and require some form of intervention.3 With the use of modem techniques 95% of
such calculi can now be removed without open surgery,4 and most can be treated by ESWL alone. Some ureteral stones cannot be treated with or fail to respond to ESWL but can be fragmented intraureterally by either ultrasonic or electrohydraulic lithotripsy; however, this procedure may damage the ureter. Laser-induced shock-wave lithotripsy with a flash-lamp-pumped tunable dye laser was introduced in 1985 and has proven to be safe and effective in fragmenting ureteral calculi.5'6 The energy affects only the material that absorbs it; thus, the laser can act selectively on the stone and not the ureter. We report our clinical experience with the flashlamp-pumped tunable dye laser, the first and only
From the Department of Surgery (Urology), Mount Sinai Hospital and University of Toronto
Reprint requests to: Dr. Kostantinos E. Psihramis, Ste. 441, Mount Sinai Hospital, 600 University Ave., Toronto, Ont. M5G IX5 CAN MED ASSOC J 1990; 142 (8)
such laser available in Canada, in the treatment of ureteral calculi that were too large for direct extraction and that could not be treated with or had not responded to ESWL or other forms of ureteroscopic lithotripsy.
Materials and methods
coumarin green as the dye the exposure parameters were as follows: 20 to 60 mJ at a wavelength of 504 nm emitted in 1.4-,us pulses at a rate of 10 pulses per second. Treatment was continued under direct vision until complete stone fragmentation (into pieces 1 to 2 mm in diameter) was achieved or until a
fragment remained that could be extracted easily with a basket. Patients with ureteral calculi were selected for For inclusion in the study all of the patients had laser therapy if their stone was too large for direct to be followed up for at least 3 months. extraction and could not be treated or had not responded to treatment with the Siemens Lithostar Results extracorporeal shock-wave lithotripter (Siemens Corp., Erlangen, Federal Republic of Germany). From April to September 1988, 27 patients (22 Stones could not be treated with ESWL if imaging or men, 5 women) underwent laser lithotripsy by one of focusing was precluded by extreme obesity or by the us (K.E.P.). The mean age was 54.4 (range 25 to 74) stones' small size, lack of or poor opacity, or location years. Each patient had a single ureteral stone; 17 over bony structures, close to the spine or over the had stones in the left ureter and 10 in the right. sacroiliac joint. Stones impacted in the ureter and Fourteen stones (52%) were in the lower third of the the presence of such ureteral disorders as stricture, ureter, 7 (26%) in the middle third and 6 (22%) in which may prevent the spontaneous passage of the upper third. The smallest calculus was 5 x 6 mm fragments after ESWL, were indications for laser and the largest 13 x 26 mm (mean 8 x 11 mm). lithotripsy. In some cases the patients opted for laser The indications for laser lithotripsy were inabilitreatment because of the long wait for ESWL. ty to localize the stone for ESWL (in nine cases), Laser lithotripsy was performed under general inability to focus on the stone for ESWL (in seven), or spinal anesthesia. Ureteroscopy was performed failed ESWL (in five), impaction of the stone and with the 8.5 French (F) rigid Wolfe ureteroscope thus probable ESWL failure (in four) and refusal to (Richard Wolfe Medical Instruments Corp., Rose- wait for ESWL (in two). All of the patients in whom mont, Ill.) or the 7.2 F semirigid LaserTripter Mini- ESWL failed or could not be used were treated with Scope (Candela Laser Corp., Wayland, Mass.). The the laser; none had alternative forms of ureteroscopquartz laser fibre is silicone-coated and has a diame- ic lithotripsy or open surgery. ter of 250 jAm, small enough to pass through a Of the calculi 20 (74%) were successfully treated 22-gauge needle. About 5 mm of the silicone coating with the laser alone: 12 (60%) were completely was removed and the fibre tested. The fibre was fragmented and 8 (40%) partially fragmented and placed inside a 4 F open-ended ureteral catheter, removed by a basket during the same procedure. which was then passed through the working port of Laser therapy was partially successful in five patients the 8.5 F ureteroscope, and the fibre was brought (19%): in three ESWL was required because sizeable into view (Fig. 1). The laser was turned on, and with fragments (greater than 5 mm in diameter) had the fibre directly on the stone the stone was treated. migrated from the upper portion of the ureter into The MDL-1 LaserTripter (Candela Laser Corp.) the kidney during laser treatment; in the other two, is a tunable flash-lamp-pumped dye laser. With basket extraction of residual fragments was done at a later date on an outpatient basis because of renal colic. Two stones (7%) could not be fragmented, and the procedure was considered to have failed; one stone required two ESWL treatments, and the other was removed percutaneously. The mean number of laser pulses used was 1090 (range 187 to 3254); this represents a mean exposure time of 1 minute and 49 seconds. The mean duration of anesthesia was 72 (range 20 to 108) minutes, and the mean hospital stay after treatment was 2 (range 1 to 10) days. In no case did the laser energy damage the Fig. 1: Quartz laser fibre is placed inside open-ended ureter. One patient suffered a minor ureteral perfoureteral catheter, which is passed through working port ration from the tip of the ureteroscope that healed (large arrow) of 8.5 French ureteroscope, and brought into spontaneously after 7 days of catheter drainage. view (small arrow). There were no other complications. 834
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None of the patients became septic or had a positive urine culture. All received an intravenously administered antibiotic, usually cefazolin, 500 mg every 8 hours for 24 to 48 hours, and at discharge they were given an antibiotic, usually doublestrength trimethoprim-sulfamethoxazole, 160 and 800 mg respectively, to be taken orally twice daily for 1 week. Renal colic developed only in the two patients who later required extraction of residual fragments with a basket; the others passed the fragments without any pain. Twenty patients (74%) had no residual fragments at discharge. At follow-up 3 months later plain abdominal roentgenography and intravenous pyelography revealed no residual fragments in 26 patients (96%). One patient, in whom a large calculus in the middle portion of the ureter had not responded to laser lithotripsy but did respond to two ESWL treatments, had residual nonobstructing fragments. None of the patients had ureteral obstruction from stricture or any other abnormality.
rates and the 96% stone-free rate at 3-months followup are similar to those reported previously.56 All of the patients would have required more invasive therapy if the laser had not been available. We believe that laser lithotripsy is a safe and effective method of ureteral stone fragmentation. Although ESWL, with its high success rate and low morbidity rate, is and should remain the treatment of choice for most renal and ureteral calculi, laser lithotripsy is a useful adjunct, and in specific cases it may be the best, if not the only, alternative to open surgery. Advantages over other forms of ureteroscopic lithotripsy include the protection of surrounding tissue and the ability to use small-diameter instruments, which permit passage into essentially all ureters. Renal calculi can also be treated with laser lithotripsy; the fibre can be passed through a flexible ureteroscope or inserted percutaneously. In addition, the laser can aid in the treatment of sequestered calculi, such as those in calyceal diverticula, or calculi that are resistant to other forms of therapy. Biliary calculi have proven amenable to laser fragmentation'°0" and may also benefit from laser lithotripsy, at least under specific circumstances. Laser treatment may eventually be performed with the aid of a fluoroscope, through acoustic and plasma-guided signals. This will obviate the need for direct ureteroscopic visualization and will allow the procedure to be performed without anesthesia on an outpatient basis.
Continuous-wave (CW) lasers, such as the carbon dioxide, argon and neodymium:yttrium-aluminum-garnet crystal lasers, create constant energy that results in thermal changes in the target site. CW lasers do not fragment urinary stones but, rather, cause heat vaporization of their surface. Energy levels of 2000 to 3000°C are needed to vaporize urinary calculi, and therefore the surrounding tissue will be damaged before the stone can be ablated.7 References The pulsed tunable dye laser has characteristics that allow stone fragmentation without tissue inju- 1. Chaussy C, Schmiedt E, Jochan D et al: First clinical ry.8 The energy is emitted for only 1.4 ,us; thus, even experience with extracorporeally induced destruction of kidney stones by shock waves. J Urol 1982; 127: 417-420 though the power is high (106 W) the cumulative heat production and degree of resultant tissue injury 2. Drach GW, Dretler S, Fair W et al: Report of the United States Cooperative Study of Extracorporeal Shock Wave are low. In addition, because the selection of an Lithotripsy. J Urol 1986; 135: 1127-1133 appropriate dye, such as coumarin green, results in 3. O'Flynn JD: The treatment of ureteric stones: a report on the emission of wavelengths that lie between the 1120 patients. Br J Urol 1980; 52: 436-438 major absorption bands of hemoglobin, the sur- 4. Kahn RI: Endourological treatment of ureteral calculi. J Urol 1986; 135: 239-243 rounding tissue does not absorb the energy as readily 5. Dretler SP, Watson G, Parrish JA et al: Pulsed dye laser as the stone does; thus, higher energy levels can be fragmentation of ureteral calculi: initial clinical experience. J used without damaging tissue.9 Urol 1987; 137: 386-389 Fragmentation has been postulated to occur 6. Coptcoat MJ, Ison KT, Watson G et al: Lasertripsy for ureteral stones: 100 clinical cases. J Endourol 1987; 1: 119through the formation of a "plasma" at the stone 121 surface.5 This plasma, a rapidly expanding cavity of 7. Mulvaney WP, Beck CW: The laser beam in urology. J Urol ions and electrons, quickly collapses after the laser 1968; 99: 112-115 dye laser for pulse and produces a shock wave that gradually 8. Watson G, Murray S, Dretler S et al: The pulsed 195-198 138: calculi. J Urol 1987; urinary fragmenting fragments the stone. The rate of fragmentation 9. Idem: An assessment of the pulsed dye laser for fragmenting depends on the stone's composition and size. Calculi calculi in the pig ureter. Ibid: 199-202 made of calcium oxalate dihydrate, struvite, apatite 10. Nishioka NS, Levins PC, Murray SC et al: Fragmentation of biliary calculi with tunable dye lasers. Gastroenterology 1987; and uric acid are more fragile and fragment more 250-255 easily than those made of calcium oxalate monohy- 11. 93: Kozarek RA, Low DE, Ball TJ: Tunable dye laser lithotripsy: drate, cystine and calcium phosphate. in vitro studies and in vivo treatment of choledocholithiasis. The complete (74%) and partial (19%) success Gastrointest Endosc 1988; 34: 418-421 CAN MED ASSOC J 1990; 142 (8)