A flexible CO 2 laser fiber for operative laparoscopy*

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1 FERTILITY AND STERILITY Copyright 986 The American Fertility Society Vol. 46, No., July 986 Printed in U.SA. A flexible CO 2 laser fiber for operative laparoscopy* Michael S. Baggish, M.D.t Mohamed M. ElBakry, M.D.:/: Department of Obstetrics and Gynecology, State University of New York, Health Sciences Center at Syracuse, Syracuse, New York A flexible, hollow fiber measuring.5 mm diameter was used in conjunction with the laparoscope to deliver a CO 2 laser beam to the rabbit uterine horn. The fibers tested consistently transmitted 5 to 5W of laser power without loss of input mode. Several fiber-to-target distances were evaluated from the standpoint of crater characteristics. Microscopic sections were studied, and crater heights and widths were quantified. All lesions produced by the CO 2 laser fiber closely mimicked those delivered by the freehand piece or micromanipulator. In two chronic experiments, rapid fibrosis and "filling in" of the craters was evident at 5 days. No adhesions were observed. The CO2 laser fiber has several advantages over current techniques for the performance of laser laparoscopy as well as over alternative systems, e.g., neodymium:yttriumaluminum-garnet (Nd: YAG) and argon-coupled fibers. The CO2 laser fiber will further increase the options available to the gynecologist for operative endoscopy. Fertil Steri! 46:6, 986 Delivery of a carbon dioxide (C02) laser beam to intraabdominal structures via the laparoscope was first described in 979. Subsequently several reports 2-4 have appeared in the literature describing laser laparoscopy for the treatment of pelvic endometriosis,5, 6 section of the uterosacral ligaments, 7 lysis of adhesions,5 and performance of neosalpingostomy.8 Although the technique of laserlaparoscopy can be mastered by mostexperienced laser surgeons, several disadvantages are inherent to the procedure. The first and most important deficiency is the still-cumbersome delivery system. The CO2 beam must be delivered Received January 9, 986; revised and accepted March 25, 986. *Supported in part by Xanar, Inc. treprint requests: Michael S. Baggish, M.D.,. Professor and Chairman, Department of Obstetrics and Gynecology, State University of New York, Upstate Medical Center, College of Medicine, 750 East Adams Street, Syracuse, New York 320. :j:fellow in Reproductive Endocrinology, Zagazig University, Zagazig; Egypt. 6 Baggishand EIBakry Flexible CO 2 laser fiber through the articulated arm via the 5-mm (diameter) operating channel of a special 2-mm single puncture laparoscope or through double-lumen second-puncture probes. The latter measure 7.5 mm in diameter and are introduced with an 8-mm trocar and sleeve. The probes range in length from 23 cm to 33 cm. Second, both single- and double- puncture delivery systems are rigid, and the operator is more or less locked into the entry angle of the probe. If the probe is not in line with the target tissue, a reentry insertion at a different location is required. Third, the helium/neon aiming beam is frequently difficult or even impossible to see unless the intensity of the laparoscopic light source is reduced. Finally, beam alignment may require multiple adjustments during the procedure. For many years, gynecologic laser surgeons have eagerly anticipated a small-diameter, flex. ible fiber that could be used in conjunction with endoscopes to deliver the CO 2 laser beam into body cavities and other small spaces. Although neodymi um:yttri um-al umin urn-garnet

2 head ofaxanar Articulator laser (Xanar, Inc.) by an extension tube incorporating a focusing lens and an alignment yoke. The yoke was fitted with screws for adjustment in the X-and Y-axis and also for rotational adjustments. A special inlet port was built into the connecting tube to allow for the transmission of CO2 gas through the fiber for prevention of plume, moisture, and other debris from being deposited within the fiber. Before insertion of the fiber into the rabbits' abdomen, the laser beam was aligned with a Coherent 20 power meter (Coherent, Palo Alto, CA), and the X- and Y-axis were adjusted to produce a 0.5-mm spot with the highest power reading. Generally, metered power settings could be approximated at the end of the fiber; that is, maximal power loss was 20%. In every case, several test spots were placed on a dry wooden tongue blade with the laser fiber. Maximal power and the smallest spots were further documented by observing the depth of the crater produced. Figure Flexible CO 2 laser hollow fiber measuring 75 em in length. (Nd:YAG)9 and argon laser systems lo are capable of transmission via small-caliber fibers, those particular wave lengths have other undesirable effects.ll Unfortunately, to date, prototype CO 2 fibers have required heavy cladding, lost the entry mode during transmission, and/or delivered the beam at significantly reduced power. This paper reports an investigation of operative laparoscopy by use of a hollow, flexible fiber measuring.5 mm in diameter to transmit the CO 2 laser beam. FIBER MATERIALS AND METHODS The CO 2 laser fiber was supplied and invented by Laakmann Electro-Optics, Inc., San Juan Capistrano, CA, a division ofxanar (Xanar, Inc., Colorado Springs, CO). The fiber extended 75 cm in length, with an outer diameter measuring.5 mm and an inner square cross-section of 0.5 mm per side. The fiber waj) constructed of dielectrically coated aluminum and could subtend an arc of 90 without adversely compromising its integrity (Fig. ). One end of the fiber was attached to the PROCEDURE Eight female albino New Zealand rabbits underwent operative laparoscopy for the determination of the efficacy of the hollow laser fiber. Six animals were immediately sacrificed upon completion of surgery, and two animals were kept alive for 5 days postoperatively and then were sacrificed. The animals' weights ranged from 3.5 to 4.5 kg, and all were anesthetized with ketamine 3.5 mg/kg and xylazine 5 mglkg. The abdomens were shaved and cleansed with surgical soap. A 0.5-cm superficial incision was made in the anterior abdominal wall skin in the midline approximately.5 cm inferior to the xiphoid. A touhy needle was then inserted into the peritoneal cavity and a CO 2 pneumoperitoneum created; approximately of gas was insufflated. After sufficient pneumoperitoneum had been created, a 7 -mm trocar was placed into the abdomen through the previously noted incision and followed by insertion of a 6.5-mm laparoscope (Carl Storz, Culver City, CA). A Circon (Circon Microvideo, Santa Barbara, CA) low light level video camera with a beam splitter was attached to the laparoscopic eyepiece in order to record the laparoscopy and to allow observers and assistants to view the procedure. Inspection of the pelvic viscera was performed first. Next, with the use of a 2.5-mm trocar and sleeve (Richard Wolf, Rose- Vol. 46, No., July 986 Baggish and ElBakry Flexible CO 2 laser fiber 7

3 Table. Specifications for Operative Laparoscopy Using a Flexible CO 2 Laser Fiber Rabbit Fiber to target distance mm Power Total craters w 5,0,5 6 5, 0, 5 5 5, 0, 5 5 mont, IL), a second puncture was made in the abdomen under direct vision 2 cm below and to the right of the initial puncture. The trocar obturator was removed, and the laser fiber was then inserted.. Several imprints were fired into the uterine horns and peritoneum at five estimated distances and at three different power settings (Table ). Laser time was gated at 0.2 seconds. Six animals were sacrificed at the end of the procedure; the uterine horns and adjacent peritonium were removed, fixed, sectioned, and stained with hematoxylin and eosin. The wounds were studied for geometric characteristics, including width and depth of the crater. The measurements were quantified by means of the Zidas (Carl Zeiss, Thornwood, NY) imaging computer system. Two animals were allowed to live for 5 days, then were sacrificed. The uterine horns were removed, sectioned, and studied in a fashion similar to that used in the acute study. ing on the laser power and distance of the fiber from the tissue. The wounds ranged from superficial to deep lesions (Figs. 2 and 3). At 5 W, the laser beam at 2 mm distance rapidly cut through the uterine horn and penetrated the uterine cavity (Table 2). Accumulated vapor was evacuated either with a 5-gauge needle inserted into the abdomen where needed or through a third puncture probe. With each case oflaser laparoscopy, the fiber was realigned and the power tested. The wounds were typical of those produced by a nonfiber delivered CO 2 laser beam and thus showed that mode and power remained intact. No visible deterioration of the fiber was observed and no misfiring or laser accident occurred. Maximal impact on tissue was observed when the tip of the fiber was approximately 2 mm from RESULTS The fiber proved durable and could be used for several experiments. Although several prototypes were tested, the basic fiber designs were similar. Failure to channel gas through the fiber resulted in the deposition of debris and loss of power. The helium/neon beam was difficult to see, but this' did not prove to be a major deficit because the fiber could be brought close to the target and then accurately aimed. Because the diameter of the fiber was small, it could be placed into small spaces; because it was stiff, it could also serve as a fine manipulator of intraabdominal structures. When a third puncture was made and a probe inserted, the fiber could be maneuvered and aimed at virtually any structure. The imprints placed in the uterine horns were discrete and could be adjusted in depth, depend- Figure 2 (A), Typical V-shaped crater produced by the continuous-wave mode of the CO 2 laser. This wound was delivered to the rabbit uterine horn by the hollow CO 2 laser fiber (original magnification, x 55). (B), Detail of wound 2A showing wnes of vaporization, necrosis, and reversibl injury (original magnification, x 65). 8 Baggish and Emakry Flexible CO 2 laser fiber

4 Figure 3 Shallow lesion produced by CO 2 laser fiber delivered at a distance of 3 mm and a power of 5 W (original magnification, x 55). the target. Beyond 5 mm, the power losses were 60%. At 5 W of power and a distance of2 to 3 mm, fine craters were placed into the peritoneum measuring 0.25 mm x 0.27 mm (Fig. 4). By 5 days, fibrosis had virtually filled the defects created in the uterine horns (Fig. 5). No adhesions were noted. The deepest wounds were produced at the highest power tested, i.e., 5 W with the fiber tip at 2 mm. No reduction of power was observed because of the CO2 atmosphere. repeatedly. Compared with the current methodology for laser laparoscopy, the flexible fiber was four times smaller and substantially more convenient to use. A major benefit to fiber technology was the elimination of the necessity of realigning the beam. The latter circumstance had been observed with the use of alignment cubes mounted to articulated arms. Additionally, even slight changes in the axis of the articulated arm tended to throw off beam alignment. One disadvantage of the current fiber was that the helium/neon aiming beam was difficult to visualize. Although this was not a critical factor because of the close proximity of the tip to the target, nevertheless, a more visible aiming beam would be a valuable addition to the technology. A second possible disadvantage was the fiber's relatively short length. Its ability to predict the lesion created has been an advantage of the CO 2 laser, compared with the DISCUSSION The principal advantages of the fiber tested in these experiments were its small caliber, its flexibility, and its ability to transmit mode and power Table 2. Acute Lesions Produced by Hollow Laser Fiber Mean crater dimensions Fiber to target Laser l'0wer distances setting Height Width mm W mm Figure 4 (A), Shallow wound placed in rabbit peritoneum via CO 2 laser fiber (original magnification, x 55). (B), Sharp demarcation of crater shown in Figure 2A (original magnification, x 65). Vol. 46, No., July 986 Baggish and ElBakry Flexible CO 2 laser fiber 9

5 Figure 5 At 5 days, a crater placed in the rabbit horn has been "filled in" by fibrosis. No adhesions were noted in the chronic experimen~. Nd:YAG laser. Likewise, the superior vaporizing characteristics offered by the CO2 fiber make it a superior alternative to the argon laser. Additionally, the CO 2 laser does not require the operator to wear special tinted glasses or to incorporate protective filters into the endoscope. Such protective eye gear is not only inconvenient to use but makes accurate visualization of the diseased tissue difficult. For these reasons, the CO2 laser is a much easier instrument to work with, compared with other fiber-conductiong light sources. Because the CO2 laser fiber performed well even at 5- to 5-W levels, it could be used with lower-powered, less expensive lasers. Currently, several office laser systems with a maximum power output of 20 W could incorporate this fiber technology.. Although our studies were performed with double-puncture techniques, the fiber offers several major improvements to current single-puncture laparoscopy technology: () The fiber allows the operating laparoscope to be used in its panoramic mode with the laser tightly focused. (2) The fiber allows the surgeon to view structures clearly between the laser beam and the target. (3) With the reduction of the diameter of the operating channel, smaller single-puncture endoscopes can be used. By incorporating deflectors at the end of either single-or double-puncture endoscopes, the direction of the fiber can be altered at will. Finally, because the current fiber is constructed of metal, it is sturdy and has little risk of breaking off in the abdominal cavity, a potential risk of the more fragile quartz fibers. The CO2 laser fiber can be anticipated to increase the options for operative endoscopy further and should allow an even larger number and variety of outpatient procedures to be performed. Furthermore, reduction in laporotomy cases will ultimately translate into a lower risk for future adhesion formation and thus benefit the patient. REFERENCES. Bruhat M, Mage C, Manes M: Use of the CO 2 laser via laparoscopy. In Laser Surgery III, Proceedings of the 3rd International Society for Laser Surgery, Edited by I Kaplan. Tel Aviv, Jerusalem Press, 979, p Tadir Y, Kaplan I, Zuckerman Z, Ovadia J: Laparoscopic CO 2 laser sterilization. In Human Reproduction, Edited by K Semm, L Mettler. Amsterdam, Excerpta Medica, 98, p Daniell JF, Brown DH: Carbon dioxide laser laparoscopy: initial experience in experimental animals and humans. Obstet Gynecol 59:76, Daniell JF, Pittaway DE: Use of the CO 2 laser in laparoscopic surgery: initial experience with the second puncture technique. Infertility 5:5, Daniell JF: Laser laparoscopy. In Basic and Advanced Laser Surgery in Gynecology, Edited by MS Baggish. Norwalk, Appleton-Century-Crofts, 985, p Martin DC: CO 2 laser laparoscopy for the treatment of endometriosis associated with infertility. J Reprod Med 30:409, Feste JR: Laser laparoscopy: a new modality. J Reprod Med 30:43, Daniell JF, Herbert CM: Laparoscopic salpingostomy utilizing the CO 2 laser. Fertil Steril 4:558, Lomano JM: Photocoagulation of early pelvic endometriosis with the ND: YAG laser through the laparoscope. J Reprod Med 30:77, Keye WR, Dixon J: Photocoagulation of endometriosis by the argon laser through the laparoscope. Obstet Gynecol 62:383, 983. FisherJ: Principles of safety in laser surgery and therapy. In Basic and Advanced Laser Surgery in Gynecology, Edited by MS Baggish. Norwalk, Appleton-Century-Crofts, 985, p Baggish and Emakry Flexible CO 2 laser fiber