Initial evaluation of the use of the potassium-titanyl-phosphate (KTP/532)* laser in gynecologic laparoscopy

Transcription

1 -- FERTU.JTY AND STERILITY Copyright c 1986 The American Fertility Society Printed in U.SA. Initial evaluation of the use of the potassium-titanyl-phosphate (KTP/532)* laser in gynecologic laparoscopy James F. Daniell, M.D.t Wayne Miller, R.N. Robert Tosh, M.D. Women's Health Group, Nashville, Tennessee A new surgical laser, the potassium-titanyl-phosphate 532 nm laser (Laserscope,. Santa Clara, CA) has recently become available for investigative procedures in gynecology. This article reports initial investigation of this laser energy at laparoscopy with the use of a flexible fiberoptic delivery system in rabbits and patients with endometriosis. Tissue effects on peritoneal structures of rabbits with laparoscopic firing of this new laser demonstrated the ability to accomplish surface vaporization without bowel perforation or penetration> 2 mm. In ten patients with pelvic endometriosis and pain, effective laparoscopic vaporization of implants has been safely accomplished with ease. Early follow-up revealed symptomatic improvement in all patients. This new laser is easy to use laparoscopically, appears safe in early investigations, and effectively reduces early postoperative pain associated with pelvic endometriosis. Fertil Steril 46:373, 1986 Several surgical lasers have already been evaluated for use laparoscopically in gynecology. These include the carbon dioxide laser which was initially reported by Bruhat et all and Tadir et a1. 2 and then more recently in North America:. 3 -s The argon 7 and the Nd:YAG 8 lasers have also been used experimentally in animals and humans. The advantages of the last two lasers are that they can be passed through flexible fiberoptic delivery systems and thus are much easier to use. A new potassium-titanyl-phosphate laser (KTPI 532) (Laserscope, Santa Clara, CA) has recently become available for investigational use in gynecology. The laser energy generated results in a beam that can pass through a flexible fiber with Received March 3, 1986; revised and accepted May 15, *Laserscope, Santa Clara, California. treprint requests: James F. Daniell, M.D., Women's Health Group, 2222 State Street, Nashville, Tennessee up to 12 w of energy available to the tissue. This laser produces a visible green beam at a wavelength of 532 nm. This paper reports our initial investigations of this laser used laparoscopically in rabbits and in a series of patients with pelvic endometriosis. MATERIALS AND METHODS Initial laboratory investigations of the KTP/532 laser were performed with virgin white New Zealand rabbits. Laparoscopy was performed under anesthesia in 4 rabbits, and the 600-f.Lm core flexible quartz fiber delivery system was used both through the 3-mm operating channel of a laparoscope and through a 3-mm second puncture probe modified to allow passage of the small flexible fiber. The tip of the laser fiber was placed 1 to 2 mm from the surface of the organ to be photocoagulated under laparoscopic control with Daniell et ai. Laparoscopic use of the KTP/532 laser 373

2 a setting of 5 W on the KTP/532 laser. Firing duration intervals of 1, 5, and 10 seconds were used. The laser was selectively fired at the bladder, uterine horns, ovary, sigmoid colon, small bowel and the lateral lower pelvic sidewall. Immediately following laparoscopy the animals were sacrificed and tissue sections taken of the areas of impact and submitted for histologic evaluation. Following approval of our investigational protocol by the Food and Drug Administration and the hospital human experimentation committee at West Side Hospital in Nashville, Tennessee, a series of patients with symptoms suggestive of pelvic endometriosis were recruited for potential ablation of the endometriosis at laparoscopy with the use of flexible quartz fiber delivered from the KTP/532 ~aser. Ten patients with pelvic pain and! or dysmenorrhea who were thought to have endometriosis signed the consent forms prior to their diagnostic laparoscopies. At the time of laparoscopy in the ten patients in which endometriosis was encountered, videotaping was done of the pelvis both before and after laser therapy. The standard operative note was dictated to reflect the location and size of all lesions present. In addition, the new revised American Fertility Society forms 9 for classification of endometriosis were filled out immediately after the surgical procedure on all patients. The KTP/532 laser was used to ablate all the visible implants of endometriosis with a setting of 5 Wand firing the laser on continuous mode until each individual implant was seen to be vaporized and/or photocoagulated. Only patients with mild or moderate disease were selected for inclusion in this pilot study. After vaporization of all visible implants of endometriosis, the uterosacral ligaments were vaporized just posterior to the cervix on each side. This was done for a length of approximately 1.5 cm and to a depth of approximately 1 cm. All procedures were done on an outpatient basis with general endotracheal anesthesia, all patients being discharged within 6 hours of surgery. No postoperative danazol or other drug treatment for endometriosis was used.in this group of patients. The patients were asked to keep a record oftheir postoperative discomfort and symptoms of pain or dyspareunia or dysmenorrhea. They were seen at 6 weeks and 3 months for follow-up, at which time they were questioned concerning the level of their symptoms, compared with those prior to the diagnostic laparoscopy and surgery with the laser. RESULTS In the rabbits there were no complications from aiming and firing the laser. It was extremely easy to perform the procedure by merely delivering the small flexible fiber into the peritoneal cavity under laparoscopic control and holding it close to the tissue. The visible green laser beam made an easy target for aiming and firing the laser. Limited smoking from vaporization did occur with firing but could be vented from the rabbit's peritoneal cavity easily in the standard fashion used for carbon dioxide laser laparoscopy. Histologic evaluation of the tissue sections obtained in the rabbits revealed no effect at firing intervals of 1 second. With 10 seconds' firing at the tissues, all the lesions showed only surface tissue coagulation with a depth of histologic change no deeper than 2000 J..Lm. The visible zones of tissue effect on the colon and small bowel extended minimally into the outer muscularis layer. In the ten patients undergoing ablation of endometriosis and transection of the uterosacral ligaments with the KTP/532 laser, there were no surgical complications. As in the rabbits, the delivery system was extremely easy to use, and visibility of the green laser beam was excellent at laparoscopy. Some smoking occurred with firing of the laser but was easy to vent off with the use of a 5-mm suction irrigation probe used for standard carbon dioxide laser laparoscopy (Eder Instrument Company, Chicago, IL). It was possible to effectively vaporize endometrial implants under saline irrigation because the laser beam is transmitted through fluids. The use of this wet field technique reduced smoke and allowed excellent constant visualization through the scope. No bleeding occurred in any of the areas vaporized, and there were no complications from vaporizing the uterosacral ligaments. The lateral extent of visible tissue change seen through the laparoscope appeared to be no more than 2 mm. On review of videotapes after surgery, there appeared to be somewhat more lateral tissue effects than seen with the carbon dioxide laser but less than visualized in previous animal investigations of the YAG laser at laparoscopy at our facility. Our initial clinical impression was that this was a much easier laparoscopic delivery system for use of laser energy for ablation of implants of endometriosis than that used with the carbon dioxide laser. 374 Daniell et al. Laparoscopic use of the KTPI532 laser Fertility and Sterility

3 Postoperatively there were no complications and at 6-week and 3-month follow-up; and all patients have reported either marked or some improvement in their pelvic pain, dysmenorrhea, and/or dyspareunia. DISCUSSION Numerous reports have now appeared in the literature concerning the use of the carbondioxide laser laparoscopically3.6, 10, 11 It appears that carefully trained operative laparoscopists now have the opportunity to utilize laser energy for numerous surgical procedures at laparoscopy. These include salpingostomy, adhesiolysis, vaporization of endometriosis, conservative treatment for ectopic pregnancy, and treatment of polycystic ovarian disease by vaporization of subcapsular cysts. Almost all authors have noted difficulty in being able to effectively apply the carbon dioxide laser at laparoscopy. The predominant problem has been the need to properly align and aim the helium neon target beam for the carbon dioxide laser. The carbon dioxide laser cannot be fired through any commercially available fibers, necessitating a very cumbersome method of beam alignment prior to firing it under laparoscopic control. The other problem with the carbon dioxide laser has been the difficulty in seeing the red helium neon target laser. The smoke of vaporization has also made it difficult to effectively perform extensive operative procedures with the carbon dioxide laser under laparoscopic control. Keye et al. 7 has reported animal and clinical investigations using the argon laser laparoscopically. Their work indicates that a real advantage of the argon laser is the ease of delivery that is possible because of the flexible fiberscope that can be used to introduce the laser energy into the peritoneal cavity. The problems with the commercially available argon lasers are the limited power that is available and the fact that the argon laser is absorbed specifically by reddish pigment. This possibly may limit the applications of the argon to photocoagulation of small implants of endometriosis. Further investigations of the argon laser are continuing in several centers at present in the United States. Lomano 8 has reported initial investigations of the Nd:YAG laser used laparoscopically. As in the work with the argon, he has been impressed with the ease of delivery of the fiberoptic system. One serious drawback of the use of the Nd:YAG laser laparoscopically is the depth of penetration that occurs. This may cause tissue destruction up to 5 mm in depth with the greatest amount of destruction being not on the surface of the impact area, as with the carbon dioxide laser, but 2 or 3 mm into the tissue. This property explains its ability to produce immediate and adequate hemostasis but also limits its use laparoscopically because of the potential for injury to vital intraperitoneal pelvic structures. The KTP/532 photo surgical system is a frequency-doubled Nd:YAG laser that produces all its output at532 nm. The Nd:YAG rod is continuously pumped with a krypton arc lamp. This output is then q-switched to produce the pulsing. The Nd:YAG wavelength (1064 nm) is then frequency-doubled with the crystal of KTP to produce the.final green wave, which reaches delivery devices via a fiberoptic. The fiberoptic cable then can be connected either directly into a delivery device such as a microscope with micromanipulator or attached to an optical coupler which allows fiberbased delivery to the tissue. The optical power gives 12 W maximum from the fiber within a 15-degree divergence, full angle in surgical mode. The. aim mode of the beam, which allows targeting prior to firing, produces 1 m W maximum. The KTP/532 laser differs from the carbon dioxide laser in that it has a solid state active medium Daniell et ai. Laparoscopic use of the KTPI532 laser Figure 1 The KTP/532 laser fiber is shown in this photograph passing through the 3-mm operating channel of the laparoscope. 375

4 Figure 2 The safety filter that fits over the eyepiece of the laparoscope does not reduce visibility, and the laser cannot be activated without the filter in place. Here the laser fiber is being used through a 3-mm accessory probe. versus a gas one. The energy emitted is a visible green light at 532 nm instead of the invisible 10,600 nm radiation of the carbon dioxide laser. When the green light interacts with nominal soft tissue, there is a greater amount of coagulation than with an equivalent "dosage" of the carbon dioxide laser, and thus a larger amount of necrotic damage. It is necessary for a surgeon using either laser to adjust the dosage to obtain the desired ratio of cutting, vaporization, and coagulation. Our initial investigations of this new KTP/532 laser seem encouraging. It has the advantages of being delivered by a flexible fiberoptic delivery system, which will be a definite improvement over the carbon dioxide laser. In addition, the laser generates sufficient power (12 W to tissue) to allow tissue incision and vaporization in addition to photocoagulation. Its depth of tissue penetration is similar to that of the argon and thus less than the Nd:YAG. The manufacturer is developing a 5-mm diameter rod with a lens system that can be placed over the fiber so that the spot diameter for the energy of the laser can be made 400 /-Lm. This allows fine focusing of the laser energy at laparoscopy. Such a probe for use at laparoscopy should allow the surgeon to be able to make precise incisions using this new laser's 376 Daniell et ai. Laparoscopic use of the KTPI532 laser energy. The green color of the laser makes it extremely easy to visualize the beam when firing. Another feature of the KTP/532 laser is a fail-safe optical filter which must be placed over the eyepiece of the laparoscope before the laser can be activated (Figs. 1 and 2). A user-friendly video panel that is computer-controlled allows ease of use by giving explicit instructions to the operator. The laser can be operated with a remote control unit that can be placed in a sterile bag to allow control by the surgeon if desired. Disadvantages of this new laser are its cost and the need for running water and higher voltage electrical hookups. The simplicity of delivery of this laser energy by the fiberoptic system, combined with the potential for tissue effects up to 3 mm, possibly could lead to a greater risk to patients. Thus, extra care must be taken with this laser around vital structures such as the tubes, uterus, and pelvic vessels. In this preliminary report no study of delayed effects of the KTP/532 laser on animal tissues was performed. Further chronic animal studies to assess subsequent adhesion formation and delayed tissue damage are needed and planned. In conclusion, initial studies in rabbits and humans indicate that this laser can be effectively and safely used under laparoscopic control to ablate implants of endometriosis without tissue penetration > 2 mm. Early clinical follow-up in these ten patients suggests that for up to 3 months postoperative pain and dysmenorrhea associated with endometriosis are satisfactorily reduced. Further careful evaluation of this new laser for other types of laparoscopic surgery are now under way. As iii all work with new surgical modalities, larger numbers of cases with longer follow-up will be necessary before any specific conclusions concerning the efficacy of this new form of laser energy for laparoscopic surgery can be drawn. REFERENCES 1. Bruhat M, Mage C, Manhes M: Use of the CO 2 laser via laparoscopy. In Laser Surgery III, Proceedings of the Third International Society for Laser Surgery, Edited by I Kaplan. Tel A via, International Society for Laser Surgery, 1979, p Tadir Y, Kaplan I, Zuckerman Z, Edelstein T, Ovadia J: New instrumentation and technique for laparoscopic carbon dioxide laser operations: a preliminary report. Obstet Gynecol 63:582, 1984 Fertility and Sterility

5 3. Daniell J, Brown D: Carbon dioxide laser laparoscope: initial experience in experimental animals and humans. Obstet Gynecol 59:761, Daniell J, Pittaway D: Use of the CO 2 laser in laparoscopic laser surgery: initial experience with the second puncture technique. Infertility 5:15, Kelly RW, Robert DK: CO 2 laser laparoscopy: a potential alternative to danazol in the treatment of stage I and II endometriosis. J Reprod Med 28:638, Daniell JF, Herbert CM: Laparoscopic salpingostomy utilizing the CO 2 laser. Fertil Steril 41:558, Keye WR Jr, Matson GA, Dixon J: The use of the argon laser in the treatment of experimental endometrious. Fertil Steril 39:26, Lomano JM: Photocoagulation of early pelvic endometriosis with the Nd:YAG laser through the laparoscope. J Reprod Med 30:77, The American Fertility Society: Revised American Fertility Society classification of endometriosis: Fertil Steril 43:351, Martin DC: CO2 laser laparoscopy for the treatment of endometriosis associated with infertility. J Reprod Med 30:409, Feste JR: CO 2 laser neurectomy for dysmenorrhea. Laser Surg Med 3:27, 1984 Daniell et al_ Laparoscopic use of the KTPI532 laser 377