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We developed a flexible port for NOTES which allows the use of conventional forceps for laparoscope-assisted surgery without change. The port is not affected by the location of the through hole in the gastrointestinal tract or vagina which elicits a problem in conventional NOTES, and its length can be adjusted during surgery by cutting the port itself. The port is made of polymer resin with a low friction coefficient. Furthermore, the port walls have a square wave structure which contributes to (1) the prevention of devices, for example, endoscope, from getting stuck at the time of insertion and retrieval, (2) the prevention of port slippage in the surgical opening for port insertion, (3) the prevention of unexpected port removal, (4) the prevention of port bore deformation, and (5) the improvement of port flexibility in the longitudinal direction. We validated the insertion and retrieval capacities of commercially available forceps for laparoscope-assisted surgery and power devices. Furthermore, we used the flexible port to conduct cholecystectomy and partial gastrectomy. We could confirm that the selection of the flexible port diameter according to the device type allowed the smooth insertion and retrieval of the device and that the port produced no air leakage. We affirmed that it is possible to conduct surgery by the cross or parallel method similarly to single port surgery. We considered that the flexible port has a potential of becoming a revolutionary port in NOTES.
Natural orifice transluminal endoscopic surgery (NOTES) is a surgical procedure by which an endoscope penetrates the gastrointestinal (GI) wall through natural orifices, for example, mouth, anus, and vagina, to conduct intra-abdominal surgery.
Therefore, the positional relationship among the natural orifice, the site of GI wall penetration, and the target organ for surgery is important.
Previous studies have described an attempt to perform colectomy by the ensured intra-abdominal route after setting a port for abdominal wall-penetrating laparoscope as the transrectal route [1, 2] and the use a straight port for abdominal wall-penetrating endoscope in the vaginal fornix . However, the diversion of ports for laparoscope-assisted surgery has elicited the following problems: (1) shortness of port length, (2) hardness of the port, (3) and straight shape of the port. In problem (1), there are patients for whom surgery cannot be initiated because the port does not reach the site of intra-abdominal penetration in the GI tract or vagina; the port falls from the surgical opening during surgery, thus requiring a long time for reinsertion. In problem (2), the site of port insertion in the GI tract or vagina which was created to conduct NOTES is injured. Furthermore, air leakage readily occurs from the site of port insertion in the GI tract or vagina. In problem (3), a setting occurs in which surgical forceps and surgical knives do not reach the target organ for surgery because the surgical opening in the rectum or vagina and the target organ for surgery are not located on the same straight line as the port.
We developed a port capable of exerting the following features to solve the abovementioned issues when using the conventional port and conducted an in vivo study. (1) We developed a material which allowed the adjustment of port length at will by means of a cutting device in the operating room. (2) We adopted a deformable structure for the port shape to make it fit the configuration of the rectal orifice or vagina which the port penetrates. Furthermore, we developed a sealing structure to delete air leak which occurs between the port and the device. (3) We adopted a flexible port which is freely bendable by 360degrees and developed a structure which makes the port be adaptable to the patient's proper physique.
The device set required to insert the flexible port is shown in Figure 1. The set is composed of the flexible port itself, the hook wire for traction into the abdominal cavity, and the disposable surgical drape.
The features of the flexible port are listed as follows.
The advantages generated by the above features of the flexible port are listed as follows.
The in vivo study was approved by the Animal Ethics Committee at the Jichi Medical University, and three farm pigs of 30 to 40kg in body weight were used. The transrectal route was established in two male pigs, and the transvaginal route in one female pig.
The schemes of the transrectal route and the transvaginal route ensured by the flexible port are shown in Figure 2. The flexible port is designed to be flexibly adaptable to the intra-abdominal structure and to be usable when inserted into the abdominal cavity by any route and in any direction. The transrectal route shown in Figure 2(a) and the transvaginal route shown in Figure 1(b) are considered when conducting surgery of an upper abdominal organ by using conventional forceps for laparoscope-assisted surgery without change. In the present device insertion study, we used the flexible port as shown in Figure 2(a) and 2(b). Furthermore, we conducted cholecystectomy and partial gastrectomy as shown in Figure 2(a).
We used one female pig and one male pig to conduct the device insertion study with the ports of 5mm, 7mm, and 18mm in diameter. The female pig was used in the transvaginal route study, and the male pig in the transrectal route study. Multiple devices were inserted and retrieved 10 times each. The presence or absence of the stuck device and the presence or absence of air leakage were examined as endpoints (Table 1).
We used two male pigs to conduct the surgical study by the transrectal route only, that is, cholecystectomy and pyloric partial gastrectomy (Table 2).
Forceps for laparoscope-assisted surgery (Karl Storz, Tuttlingen, Germany) were used as inflexible devices, and Roticulator (Covidien, MA, USA) as flexible forceps. Furthermore, Harmonic Scalpel (Johnson and Johnson, OH, USA) and LigaSure (Covidien, MA, USA) were used as incision devices. The surgical opening in the stomach was established on the anterior wall in the greater curvature of stomach. Two endoscopes for port setting and for monitoring during surgery (240i, Olympus, Tokyo, Japan) were used.
Setting of the flexible port and surgical procedures are as follows.
Injury and deformation of the port insertion hole: after surgery, any deformation or enlargement did not occur at all to the bore of the site of flexible port setting in the rectum and vagina.
Requisite for the length of the device used: conventional forceps for laparoscope-assisted surgery were required to have a length of 35cm or more. Both Harmonic Scalpel and LigaSure of 10mm in diameter, which were used as incision devices, had a length of approximately 35cm. Therefore, we occasionally needed to pull the stomach toward the tail with forceps of 45cm in length.
Position where the surgical opening for flexible port insertion is created: forceps, whose rod could be freely controlled at hand with respect to the degree of flexion, allowed the unlimited conduct of surgical procedures. In the case of using straight forceps, it was necessary to establish the site for port setting at a distance of 3cm or more away from the site of peritoneal reflection toward the mouth in order to avoid the forceps' hit against the pelvis.
Method to operate forceps when using the flexible port: regarding surgical procedures, it was possible to use the flexible port by the same operations of forceps as the cross or parallel method for SPS.
In conventional NOTES, there has been a risk of intra-abdominal abscess caused by bacterial intrusion from the site of endoscope admittance in the abdominal cavity when no port was used. In the case of using the port for laparoscope-assisted surgery, furthermore, there has been a risk of port fall during surgery because port length was insufficient due to port usage without change and the port surface was slippery. For the application of conventionally existing TEM technologies, an attempt has been made to insert a giant, metal, surgical opening-creating device into the anus and to create and use the transrectal route . This method causes a burden to the anal sphincter and occasionally injures the anus even when using a muscle relaxant. However, the flexible port could be set to the rectum at the surgical opening of several diameters in the GI tract only via the visual field of a colonoscope. Extension of the anus was not required during surgical procedures, which verified the advantage of the flexible port in the aspect of lessening the burden to the anus. Furthermore, there is also an attempt to use as the port for NOTES an overtube port of specified length that can reach the sigmoid colon . However, the attempt has the following problems: air leakage; time is required to close the surgical opening in the rectum; and greater risks of causing stenosis and ruptured suture due to the creation of a large surgical opening in the intestine that is not directly related to surgery.
The cuttable flexible port allows its use regardless of anatomical individual differences. Furthermore, the use of the flexible port permits the determination of the port setting position without being influenced by port length. It is necessary to create surgical openings in the GI tract as numerous as required ports. However, we could verify that no air leakage occurred at the site of port insertion because the port was atraumatically set while dilating the pinhole. We confirmed that the use of the flexible port made it possible to use conventional long-type forceps for laparoscope-assisted surgery without change.
Conventional NOTES has presented technical difficulties and required skill in operations because an endoscope or an endoscope-customized surgical instrument is used to conduct surgery. Furthermore, an endoscope is used to grasp the organ. Therefore, the weakness of bearing power and traction power made is difficult to manipulate the organ without fail. The use of the flexible port allows the conduct of surgery similarly to laparoscope-assisted surgery by using the cross and parallel methods of conventional SPS. Furthermore, the operability of forceps for laparoscope-assisted surgery will further improve if it is a device which has a mechanism to adjust the angle between the handle and the rod or to permit flexion between the rod and the apical structure.
Forceps with a length of 35cm or greater is required to conduct surgery of upper abdominal target organs (e.g., stomach and gallbladder) by using the flexible port. Most incision devices currently available have a length of 35cm. Therefore, it is necessary to use forceps of 45cm in length in order to pull the stomach toward the tail when using a cutting device for gastrectomy. We are using the currently available forceps of 45cm in length as the electrosurgical knife. Furthermore, we plan to use a 45cm rod-like metal stick to displace the intestine or an organ.
In the future, we plan to manufacture 40-cm forceps with the bendable apex and a cutting device. A variety of devices for SPS have already been designed and are ready for commercialization. We consider that the flexible port, which permits the conduct of NOTES as a device for SPS, has a potential of revolutionizing NOTES procedures. We will successively report on whether the flexible port is usable for devices for SPS which are to be commercialized later on.
We considered that the flexible port has a potential of becoming a highly safe port which allows SPS in NOTES by the transrectal and transvaginal routes.
The present study was conducted under Japan NOTES Research Grant. The authors express deep gratitude to staff members at Center for Development of Advanced Medical Technology of the Jichi Medical University for their collaboration in conducting the present study.