Application of the cavitron ultrasonic surgical aspirator (CUSA)* for gynecological laparoscopic surgery using the rabbit as an animal modelt*

Transcription

1 FERTILITY AND STERILITY Copyright if) 1992 The American Fertility Society Vol. 58. No.2, August 1992 Printed on acid-free paper in U.S.A. Application of the cavitron ultrasonic surgical aspirator (CUSA)* for gynecological laparoscopic surgery using the rabbit as an animal modelt* Bradley S. Hurst, M.D. II Caleb A. Awoniyi, Ph.D. Janet K. Stephens, M.D., Ph.D.~ Lori K. Thompson, M.D. Robert M. Riehl, Ph.D. William D. Schlaff, M.D. University of Colorado Health Sciences Center, Denver,. Colorado Objective: To study the potential application of the cavitron ultrasonic surgical aspirator (CUSA) in gynecologicallaparoscopic surgery using a rabbit animal model. Design: Twenty-six rabbits were prospectively randomized into two groups. Laparoscopically directed standard injuries were made on the randomly assigned horn and sidewall in all animals with the CUSA. Contralateral injuries were made with a contact neodymium-yttrium aluminum garnet (Nd:YAG) laser in group 1 and with bipolar cautery in group 2. Adhesion and inflammation scores were assessed for two animals in each group at 24, 48, and 72 hours, and seven animals in each group at 14 days. Setting: University animal research facility. Main Outcome Measures: Adhesion and inflammation scores were compared between animals in the CUSA versus Nd:YAG study and the CUSA versus bipolar cautery at 14 days. Results: No significant difference in uterine or sidewall adhesion scores was noted between the CUSA versus Nd:YAG or the CUSA versus bipolar cautery. Bipolar cautery produced significantly less inflammation on the uterine h0rn compared with the CUSA (3.0 ± 0.2 versus 5.3 ± 0.7, P = ), but no difference in sidewall inflammation was noted between the CUSA compared with bipolar cautery. No difference in inflammation was observed between the CUSA and the Nd: YAG laser. Conclusions: The bipolar cautery appears to be preferable to the CUSA for coagulation of uterine lesions, although dissection of the uterus is not possible with bipolar cautery. The CUSA and the Nd:YAG appear to be comparable for uterine horn dissection. Because the CUSA causes similar adhesion formation and tissue inflammation at the sidewall when compared with the Nd: YAG laser and bipolar cautery and may be less likely to damage blood vessels, ureters, or other collagen-rich tissues, the CUSA may represent a promising new surgical tool for laparoscopically directed peritoneal dissection. Fertil Steril 1992;58:444-8 Key Words: Laparoscopy, laparoscopic surgery, ultrasonic surgery, bipolar cautery surgery, adhesions, inflammation Received February 26, 1992; revised and accepted April 29, * Cavitron Ultrasonic Surgical Aspirator (CUSA), Valleylab, Boulder, Colorado. t Funded in part by Valleylab, Boulder, Colorado. :j: Presented in part at the 39th Annual Society for Gynecologic Investigation, San Antonio, Texas, March 18 to 21, Department of Obstetrics and Gynecology. II Reprint requests: Bradley S. Hurst, M.D., University of Colorado Health Sciences Center, Box B198, 4200 East Ninth Avenue, Denver, Colorado Department of Pathology. The popularity of laparoscopic surgery for gynecological indications continues to increase. Laparoscopic surgery has become a standard therapy for patients with endometriosis (1, 2), adhesions (3), and ectopic pregnancy (4). Other procedures such as myomectomy (5) and salpingoophorectomy (6) are performed by some. As techniques and instruments improve, the indications for laparoscopic surgery have increased. Despite the enthusiasm for laparoscopic surgery, all of the currently available modalities have limi- 444 Hurst et al. Techniques and instrumentation

2 Vibrating Tip To Suction Supply Figure 1 The steam sterilizable straight CUSA handpiece modified with an extended flue and vibrating tip for laparoscopic surgery. (Diagram courtesy of Valleylab, Inc., Boulder, CO) (16), resection of central nervous system tumors (17), and vessel dissection (18). The advantage of this approach is believed to be the precise removal of undesired tissue with minimal or no damage to adjacent structures. Similarly, it is possible that the CUSA may be applied in laparoscopic surgery with less risk of damage to vessels, bowel, and ureters compared with currently used modalities. To explore the potential applications of the CUSA in gynecological laparoscopic surgery, we performed a prospective, randomized study comparing tissue inflammation and adhesion formation with the use of a laparoscopically directed CUSA versus laparoscopically directed contact Nd:YAG laser or microbipolar electrocautery in the rabbit pelvis. tations. For example, monopolar electrocautery provides the ability to cut and coagulate tissue but may result in deep tissue destruction, spark gaps, and adjacent tissue injury including bowel burns. Likewise, the neodymium-yttrium aluminum garnet (Nd: Y AG) laser used with a sapphire tip effects cutting or coagulation but may cause deeper tissue injury than desired. Occasionally, these methods are preferable because of the depth of tissue destruction, but rarely is this the case in infertility surgery. Bipolar cautery provides surface coagulation, but the depth of injury is unpredictable and the ability to incise tissue is poor. Furthermore, the use of cautery and lasers can result in occult injury, which may not be diagnosed at'the time of laparoscopy. Major morbidity associated with current modalities include injury to bowel, blood vessels, or the ureters (7), and patient deaths have occurred as a result of complications. The cavitron ultrasonic surgical aspirator (CUSA; Valleylab, Boulder, CO) combines tissue fragmentation, irrigation, and tissue aspiration and allows dissection of water-dense tissue away from collagenrich structures such as blood vessels, ureters, and nerves (8). Tissue fragmentation is accomplished by a hollow titanium tip housed in a protected flue that vibrates up to 23,000 times per second (9). An irrigating fluid is delivered through the handpiece to create an emulsion while suction is provided through another portal to aspirate tissue and provide a clean operative site. The CUSA has been used in gynecological oncology surgery for tumor debulking (10, 11) and liver (12), spleen (13), and renal (14) resections. Other applications of the CUSA include mucosal proctectomy for patients with ulcerative colitis (15), isolation of the coronary arteries for bypass grafting Vol. 58, No.2, August 1992 MATERIALS AND METHODS Twenty-six sexually mature New Zealand white rabbits weighing 3.7 ± 0.2 kg were prospectively randomized into one of two groups for a laparoscopic study to compare adhesion formation and inflammation between the CUSA versus Nd:YAG laser and CUSA versus bipolar cautery. Animals were fasted for 12 hours before the induction of anesthesia for laparoscopy with xylazine 5 mg/kg intramuscularly (1M) followed by ketamine 25 mg/kg 1M and halothane 1.5% to 2% face mask. Anesthesia levels were monitored by lack of response to toe or skin pinch, lack of jaw tone, and presence of a slight palpebral reflex. The abdomen was shaved and prepared with an iodine solution. A l-cm midline incision was made in the upper abdomen, and a verres needle was inserted. A pneumoperitoneum was achieved with CO 2 Once the abdomen was tympanitic, the verres needle was removed, and an 11-mm laparoscopic trocar was inserted and a laparoscope placed through the sheath. A second incision was made at the level of the uterus, and an 11-mm trocar was placed under direct laparoscopic visualization. At this point, a randomization card was drawn to indicate the side of the CUSA injury and the method to be used on the contralateral side. Under direct laparoscopic visualization, a superficial injury was made in the uterine horn (2 cm X 5 mm) and the pelvic sidewall (2 cm X 1 cm). The injuries were made by the CUSA System 200 tabletop model using a handpiece with an extended flue and vibrating tip (Fig. 1),20% to 40% amplitude on the randomized side and on the contralateral side by either contact N d: Y AG laser (Surgical Laser Technologies, Oaks, PA) 20 watts continuous with a sapphire chisel tip cooled with filtered CO 2 or a microtip bipolar cautery at 20 watts Hurst et al. Techniques and instrumentation 445

3 Table 1 Adhesion Score and Inflammation Score in CUSA Versus Nd:YAG Study and CUSA Versus Bipolar Cautery Study at 14 Days' Adhesion score Inflammation score Uterus Sidewall Total Uterus Sidewall Total CUSA 4.4 ± ± ± 2.0 Nd:YAG 2.7 ± ± ± 1.6 CUSA 3.6 ± ± ± 3.0 Bipolar 0.0 ± ± ± ± ± ± 0.3t 0.1 ± O.lt 3.3 ± ± ± ± ± ± 0.7:1: :1: Values are means ± SE. t Uterine inflammation score CUSA versus bipolar (P < 0.05). :I: Total inflammation score CUSA versus bipolar (P < 0.05). (Valleylab, Boulder, CO). An attempt was made to make a standard injury on the ovaries. However, because of the small size and high position of the ovaries, a consistent injury could not be made. Therefore, this experimental arm was abandoned. After the procedure, hemostasis was confirmed and the pneumoperitoneum allowed to escape from the abdomen. The incisions were closed with subcuticular sutures of 4-0 polyglycoic acid. Postoperatively, the rabbits received acetaminophen, 2 mg/ml for 48 hours, and were fed ad lib immediately after surgery. At 24, 48, and 72 hours, two animals from each group were killed, and a site specific adhesion score was determined on the basis of extent (0 to 4), type (0 to 4), and tenacity (0 to 3) of the adhesions (19). Tissue was obtained for histologic evaluation from each site. Animals were killed by induction of anesthesia by ketamine and xylazine followed by pentobarbital, 750 mg given as an intracardiac injection. A laparotomy was performed immediately and a site specific adhesion score was assessed at each injury site without knowledge of the CUSA side. Tissue from each surgical site was then resected and placed in 10% formalin. The specimens were stained with hematoxylin and eosin and evaluated microscopically for inflammation on a scale of 0 to 4, with 0 representing no inflammation and 4 representing a severe inflammatory reaction, again with no prior knowledge of the type of injury (CUSA versus bipolar cautery versus N d: Y AG laser) inflicted at each site. At 14 days, the remaining seven rabbits from each group were killed, a site specific adhesion score was determined, and tissue from each site was evaluated histologically for the inflammatory response as described above. Statistics Comparisons were made between study groups using one-factor ANOVA with repeated measure- ments. A probability of <5% was considered to be significant. RESULTS Adhesions with the CUSA increased with time. The mean total adhesion score (uterus and sidewall) was 0.8 with an SE of ± 0.8 at 24 hours, 3.2 ± 2.0 at 48 hours, 4.0 ± 3.0 at 72 hours, and 6.8 ± 1.6 at 14 days. Likewise, the total inflammation score with the CUSA increased from 1.2 ± 0.8 at 24 hours, 2.8 ± 1.1 at 48 hours, 2.5 ± 0.9 at 72 hours, and 5.1 ± 0.4 at 14 days. A similar increase in adhesions and inflammation was seen with the Nd:YAG and the bipolar cautery. Adhesion and inflammation scores at 14 days were compared separately for animals in the CUSA versus Nd:YAG and the CUSA versus bipolar cautery studies (Table 1). There was a wide range in total adhesion scores for the CUSA (0 to 12) and the Nd: YAG (0 to 10) in the first arm of the study and for the CUSA (0 to 21) and the bipolar cautery (0 to 8) in the second arm of the study. Because of the wide ranges observed in the adhesion scores, there were no significant differences demonstrated between the groups. However, in the CUSA versus bipolar study, the uterine adhesion score was 3.6 ± 1.8 with the CUSA compared with no adhesions seen in the uterine horn on the bipolar cautery side (P = 0.1). The differences noted in uterine horn adhesion scores were likely a reflection of the difference in uterine inflammation with the CUSA (5.3 ± 0.7) versus the bipolar cautery (3.0 ± 0.2; P = ). Adhesions on the pelvic sidewall were comparable with the CUSA (2.1 ± 0.8) and the Nd:YAG (1.4 ± 1.0) in the first study group and the CUSA (3.7 ± 1.5) and the bipolar (3.9 ± 1.1) in the second group. There were no differences noted in inflammation on the sidewall between the CUSA versus the Nd:YAG or the CUSA versus the bipolar cautery. 446 Hurst et al. Techniques and instrumentation

4 DISCUSSION Advances in laparoscopic surgery have been made with the development of improving tools and techniques. The CUSA includes modifications of a new prototype available with nose cone extension. This modification allows the CUSA to be introduced through an operating channel for laparoscopic surgery. As described above, the CUSA's ability to remove tissue with high water content while sparing collagen-rich tissue such as ureters, large blood vessels, and nerves has been well established (8-18). These surgical principles make the CUSA potentially advantageous for laparoscopically directed peritoneal dissections on the pelvic sidewall, around the ureters, and iliac and ovarian vessels. In addition, aspiration of the dissected tissue is accomplished with the CUSA, which allows for pathological evaluations and establishment of tissue cultures (20), whereas this is not possible with cautery or laser. Despite the potential advantages, before the CUSA is used clinically for gynecologicallaparoscopic surgery, it is essential to establish that adhesions and inflammation are no worse with the CUSA than other currently used modalities. The CUSA versus Nd:YAG experiment provides evidence of comparable adhesion formation and tissue inflammation on the uterine horn and pelvic sidewall. Subjectively, the sidewall lesion could be easily performed with either device. The CUSA dissected the tissue by a "melting" effect, the contact Nd:YAG, as expected, by a combination of cutting and coagulation. On the uterine horn, use of the CUSA required application of more pressure than necessary for the sidewall in a dragging technique to initiate the dissection, probably because of the higher amount of collagen in the uterus. Nevertheless, once a surface defect was created, a satisfactory dissection could be performed. There was no difficulty in using the Nd:YAG to make an injury on the uterine horn. In the CUSA versus bipolar cautery group, the total adhesion score was considerably less for the bipolar cautery. Adhesions on the uterine horn were seen with only 1 animal (at 72 hours) in 13 with bipolar cautery. The difference seen in adhesions on the uterine horn is likely a reflection of the differences noted between inflammation with use of the CUSA or bipolar cautery on the uterine horn. Because tissue inflammation is less and fewer adhesions are formed by the use of bipolar cautery, bipolar cautery may be better than the CUSA for coagulation of uterine lesions. However, dissection is not possible with the bipolar cautery, thus limiting its applications in uterine surgery. For the pelvic sidewall, there were no differences between adhesion formation or inflammation when the CUSA and bipolar cautery were compared. Coagulation of the tissue was easily accomplished with bipolar cautery, but dissection was not possible. Both the cautery and the Nd:YAG can cause deeper tissue injury than desired. Although identification of anatomy is essential during any surgical procedure, it is not common practice during laparoscopic surgery to widely open the retroperitoneal spaces and clearly identify the ureters and iliac vessels during a routine fulguration of endometriosis. Although complications are rarely encountered with skilled laparoscopic surgeons, complications are likely to increase as more invasive procedures are done by less highly trained individuals. In this study, the CUSA, is shown to be comparable with the Nd: Y AG and bipolar cautery for pelvic sidewall adhesion formation. Because the CUSA has important theoretical advantages for dissection and treatment of the pelvic sidewall, we believe that this instrument may represent an important improvement over presently used techniques. Further study to carefully assess the safety margin in sidewall dissection currently is under way. REFERENCES 1. Murphy AA, Schlaff WD, Hassiakos D, Durmusoglu F, Damewood MD, Rock JA. Laparoscopic cautery in the treatment of endometriosis-related infertility. Fertil SteriI1991;55: Cook AS, Rock JA. The role of laparoscopy in the treatment of endometriosis. Fertil Steril 1991;55: Operative Laparoscopy Study Group. Postoperative adhesion development after operative laparoscopy: evaluation at early second-look procedures. Fertil Steril 1991;55: Pouly JL, Chapron C, Manhes H, Canis M, Wattiez A, Bruhat M-A. Multifactorial analysis of fertility after conservative laparoscopic treatment of ectopic pregnancy in a series of 223 patients. Fertil Steri! 1991;56: Hurst BS, Schlaff WD. Laparoscopic and hysteroscopic myomectomy. In: Azziz R, Murphy AA, editors. Practical manual of operative laparoscopy and hysteroscopy. New York: Springer-Verlag, 1992: Silva PD, Kuffel ME, Beguin EA. Open laparoscopy simplifies instrumentation required for laparoscopic oophorectomy and salpingo-oophorectomy. Obstet Gynecol 1991;77: Gomel V, James C. Intraoperative management of ureteral injury during operative laparoscopy. Fertil Steri! 1991;55: Addonizio JC, Choudhury MS. Cavitrons in urologic surgery. Urol Clin North Am 1986;13: Vol. 58, No.2, August 1992 Hurst et al. Techniques and instrumentation 447

5 9. Goldsmith MF. Ultrasonic device wins neurosurgeon praise. JAMA 1983;250: Deppe G, Malviya VK, Malone JM Jr. Debulking surgery for ovarian cancer with the cavitron ultrasonic surgical aspirator (CUSA)-a preliminary report. Gynecol Oncol 1988;31: Adelson MD, Baggish MS, Seifer DB, Cassell SL, Thompson MA. Cytoreduction of ovarian cancer with the cavitron ultrasonic surgical aspirator. Obstet Gynecol 1988;72: Tranberg KG, Rigotti P, Brackett KA, Bjornson HS, Fischer JE, Joffe SN. Liver resection: a comparison using the Nd: YAG laser, an ultrasonic surgical aspirator, or blunt dissection. Am J Surg 1986;151: Moorman DW, Evans DM, Wright DJ. Segmental splenectomy using the ultrasonic surgical aspirator. Am J Surg 1988;155: Landau ST, Wood TW, Melzer RB, Lee RG, Smith JA Jr. Lasers Surg Med 1986;6: Heimann TM, Slater G, Kurtz RJ, Szporn A, Greenstein AJ. Ultrasonic mucosal proctectomy in patients with ulcerative colitis. Ann Surg 1989;210: Mitsui T, Onizuka M, Ijima H, Maeta H, Okamura K, Sakai A, et al. Ultrasonic aspiration in coronary artery surgery. Ann Thorac Surg 1987;43: Albright AL, Sclabassi RJ. Cavitron ultrasonic surgical aspiration and visual evoked potential monitoring for chiasmal gliomas in children. J Neurosurg 1985;63: Suma H, Fukumoto H, Takeuchi A. Application of ultrasonic aspirator for dissection of the internal mammary artery in coronary artery bypass grafting. Ann Thorac Surg 1987;43: Boyers SP, Diamond MP, DeCherney AH. Reduction of postoperative pelvic adhesions in the rabbit with Gore-Tex surgical membrane. Fertil Steril 1988;49: Oosterhuis JW, Lung PFL, Verschueren RCJ, Oldhoff J. Viability of tumor cells in the irrigation fluid of the cavitron ultrasonic surgical aspirator (CUSA) after tumor fragmentation. Cancer 1985;56: Hurst et al. Techniques and instrumentation