腹腔镜Endovision系统：维护和问题解决

Laparoscopic Endovision system: Maintenance and problem solving

                               
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As we enter in the Modern day, we are witnessing dawn of the new trend in which closed body operating procedures are more often being performed through minimal access. This development is the consequence of vision and work of many dedicated individuals. They include early pioneers of endoscopy who planted the seed and lastly the current pioneers who pushed and expanded these frontiers to give rise the birth of modern laparoscopy. Therapeutic laparoscopic surgery was introduced into the surgical practice recently and within a short span of time, it has become established as defacto standard for the treatment of chronic cholelithiasis and many advanced laparoscopic procedures can be performed safely. Laparoscopic surgery, what we should witness today, may be the culmination of over a hundred years of painstaking efforts from the number of pioneers within the fields of optics, instrumentation and video laparoscopic camera. Few advances in medicine occur in isolation. The innate human curiosity to peer within the body cavities can be traced back to ancient times. However, due to primitive technology and crude instruments, several ambitions were not realized. It is probably safe to say that first laparoscopy would not have been performed had it not been for the efforts of many physicians in 1800s to develop endoscope. The device developed by Theodore Stein in mid 1880 contains all the aspects of the current endoscopic documentation system. There was a crude endoscope and a high intensity light source. Illumination was made by continuously feeding a magnesium wire into an ignition chamber utilizing a clockwise mechanism. Light from this combustion was reflected to the tube utilizing a mirror. Finally the look was focused on to some photographic plate through coupling optics.

The term laparoscopy hails from a Greek word lapara, meaning “the soft the main body between ribs and hip, flank, loin” and skopein, meaning “to take a look at or survey”. First documented laparoscopy was undertaken in 1901 by Damitri Oksarovich Ott (1858-1929) of St. Petersburg, Russia, using gynecologic head mirror, another light source along with a speculum to perform the process. He termed the procedure “Ventroscopy”. In 1902, George Kelling of Dresden, Germany outlined the strategy of visualizing the peritoneal cavity and it’s contents inside a dog by inserting

a cystoscope inserted through a trocar and creating pneumoperitoneum with filtered air. Simultaneously, a Swedish surgeon, Jacobaeus in 1910, coined the term “laparoscopy” which has subsequently get to be the accepted terminology used to describe almost all types of this type of intervention. He published his experience about the technique of laparoscopy in humans the very first time. The following technological advance in laparoscopic technology was provided in 1920 by Benzamin Orndoff who created a sharp pyramidal point on laparoscopic trocar to facilitate puncture.

Professor Kalk from Germany pioneered the use of laparoscopy for disorders of liver and biliary tract. He introduced the oblique viewing optics from longitudinal axis permitting better inspection of organs, as the image could be changed by altering the viewing direction of the optics so that the lens moved around the object. In 1929 he was the first to describe dual puncture technique. The use of second puncture opened the way for the development of operative laparoscopy. The following significant development in laparoscopic technology took place 1938 when Hungarian surgeon, Janos Varess described a spring loaded needle by having an inner stylet that automatically converted the sharp cutting edge to a rounded end by a side hole. For creation of pneumoperitoneum. He was the main physician at the Komitat hospital in Hungary. The needle had initially been used to produce a pneumothorax to treat tuberculosis. The first description of operation performed under laparoscopic vision came from Fervers in 1933. He performed laparoscopic adhesiolysis with biopsy instruments. He used oxygen as distending medium and experienced “great concern” at the audible explosion and flashes of sunshine made by electrocautery within the abdominal cavity. He recommended changing to carbon di oxide as insufflating gas for creating pneumoperitoneum. Kurt Semm, a gynecologist, literally vital role within the growth and development of operative laparoscopy. It was Semm who developed the automatic insufflating device that monitored intra abdominal pressure and gas flow in 1963. Prior to this, air was introduced by most workers into peritoneal cavity by using a syringe.

Semm designed the pre tied suture loop (Roeder knot) to permit adequate haemostasis. He also created a high volume suction/irrigation apparatus with design modifications to prevent tube clogging. Many more instruments i.e. needle holder, micro scissors, clip applier, morcellator were conceptualized, created and first utilized at Kiel University by him. He also created pelvi trainer, made to teach surgeons the recording eye hand coordination and suture tying techniques He was the very first person to perform laparoscopic appendectomy in 1982 and soon thereafter, using his instruments, Erich Muhe, a surgeon from Boblingen performed first laparoscopic cholecystectomy in 1985. Unfortunately his technical presentation to Congress of German Surgical Society met with considerable resistance. The surgery was later performed with the help- of video camera in France by Phillipe Mouret in 1987.

No one has contributed extensively to the development and employ of laparoscopy in general surgery than George Berci (6) in La, in the design of instrumentation and identifying clinical situations in surgical practice where laparoscopy would materially benefit management of the patient. He pioneered the use of laparoscopy for the management of diagnostic dilemmas, especially in emergency situations, and was instrumental in the development of laparoscopy for trauma.

It's reliable advice that the development of laparoscopic surgery wouldn't have been possible with no video laparoscopic camera in 1986.This instrument allowed all members of the operating team to view operative field simultaneously, permitting the type of coordinating movements required for complex operative procedures. Prior to that operative laparoscopy was limited to the person directing the operative procedure and participation by fellow members from the surgical team was limited.

The building blocks from the laparoscopic camera may be the solid state chip sensor. The most popular sensor is charged coupled device (CCD). The CCD consists of small bits of silicone called pixels, which are arranged in rows and columns and are sensitive to light. When light strikes a pixel, the silicon emits electricity, that is transmitted to the monitor. The electronic signals are then reconstructed about the monitor to provide the recording image. The resolution from the CCD is dependent upon quantity of the pixels on the sensor. The resolution is defined as the amount of vertical lines that may be discriminated separate in three quarters from the width of the monitor screen. The laparoscopic camera requires at least 300 lines of resolution to supply a sufficient image. Now a day’s triple chip camera are available, with each chip devoted to just one color of the spectrum. Since the major spectrum is derived from three colors i.e. red, green and blue, modern three chip camera is able to reconstruct the look consisted of these three primary colors and supply excellent resolution and color but you are much more expensive.

Light source & transmission: Among the primary problems within the development of video laparoscopy was the insufficient light. A typical source of light consisted of a lamp “bulb”, heat filter, a condensing lens and manual or automatic intensity controlled circuit. Lamp or bulb is the most important the main source of light. The Quality of light depends upon the lamp used. Several Modern types of light sources are available on the market. These light sources mainly differ on the kind of bulb used. Four types of lamp are utilized recently. 1. Quartz halogen. 2. Incandescent bulbs 3. Metal halide vapor arc lamp 4. Xenon.

A normal light source (a light bulb) uses approximately 2 % in light and Ninety eight percent in heat. This heat is principally due to the infrared spectrum of sunshine and due to obstruction within the pathway of sunshine. If Infrared will travel through the sunshine cable compared to cable is going to be intolerably hot. A heat filter is introduced to filter this infrared to visit in fiber optic cable. An awesome light source lowers this ratio by making more light, but doesn't reduce the heat produced to zero. The purpose of condensing lens would be to converge the sunshine emitted by lamp to the area of light cable input. In most from the light source it's used for increasing the light intensity per square cm of area.

Most typical kind of source of light was halogen bulb. It is highly efficient crisp light source with excellent color rendering. The electrodes are made up of Tungsten. They utilize halogen gas that allows the bulb to burn more intensely without sacrificing its life. They have average life of 2000 hours. These lamps are cheap and can supply for laparoscopic surgery if low quality set up is required. However, they lack in supplying the natural white light color. Metal halide vapor arc lamp is really a mix of compounds, (mostly salts of rare earths and halides as well as mercury which provided the conduction path) is carefully chosen to produce an output which approximates to “white light” as perceived by the eye. There are two types of metal halide lamp, iron halide and gallium iodide lamp. Even though light generated was white but not exactly the replica of sun light. This issue has largely been eliminated using the introduction of high intensity Xenon source of light. Xenon lamps consist of a spherical or ellipsoidal envelope made from quartz glass, which can withstand high thermal loads and high internal pressure. For ultimate image quality, only the highestgrade clear fused silica quartz can be used. It is typically doped, although not visible to the human eye, to absorb harmful UV radiation generated during operation. The colour temperature of Xenon lamp is 6000-6400 K. The operating pressures are tens of atmospheres sometimes, with surface temperatures exceeding 600 degrees C. The light emitted by xenon lamp is slightly bluish and more natural compared to halogen lamp. However, the majority of the cameras at the moment analyze and compensate these variations by means of automatic equalization of whites (2100 K to10000 K), that allows exactly the same image to be obtained with both light sources. An effective white balancing before start of operation is an extremely good practice for receiving a natural color. The white light consists of the equal proportion of Red, Blue and Green Color and at time of white balancing your camera sets its digital coding for these primary colors to equal proportion let's assume that the target is white. And if during the time of white balancing the telescope is not visiting a perfectly white object then the setup from the camera can be really bad and also the color perception will be very poor.

Before the introduction of fiber optic cables, the light source was incorporated in the laparoscope itself which makes it heavier, and cumbersome. In 1954 a major breakthrough in technology occurred in the introduction of fiber optic cables. The principle of fiber optic cable took it's origin from the entire internal reflection of light. Light could be transmitted through a curved glass rod due to multiple total internal reflections in the walls of the rod. Light would enter on one side of the fiber and emerge in the other end after numerous internal reflections with almost all of its strength. Now a days two kinds of light cable are available in market. 1. Fiber Optic cable 2. Liquid crystal Gel cable. The optical cables comprise of the bundle of optical fiber glass thread swaged at both ends. They have a very good quality of optical transmission, but are fragile. In fact, some of the fibers may break because of repeated use. The broken fibers are seen as black spots when cable is viewed against day light. The gel cables comprise of a sheath that is filled with a clear optical gel. (Liquid crystal) and swaged at both ends by quartz Theoretically they're effective at transmitting 30% more light than optic fibers. Because of more light and better color temperature transmission this cable is recommended in those circumstances where documentation (movie, photography or TV) is performed. They pose three problems 1. The quartz swaging at the ends is very fragile, especially when the cable is hot. The slightest shock, on a bench for instance, can cause the quartz end to crack and thus result in a loss in the transmission from the light 2. These cables transmit more heat than optical fiber cables 3. They're more rigid due to metal sheath, causing them to be harder to keep. Of the very crucial invention in operative laparoscopy was by British Physicist, Harold Hopkins in 1952, who developed the thought of the rod lens system. Just before this development, endoscopes were constructed with an optical system that comprised relay and field lenses made from glass with long intervening air spaces. In Hopkins system, the roles of glass and air are interchanged such that the optical system includes air lenses and long glass air spaces. As the refractive index is now predominantly those of glass, the sunshine transmission capacity of the endoscopes is doubled. Another advantage of Hopkins rod lens system pertains to the “larger radius of clear aperture” offered at the viewing optic which was not possible with conventional endoscopes.

Light Cable: Handle it carefully and do not twist it. After the completing operation, cable should preferably be disconnected from the endoscope after which from source of light. Avoid direct fall of sunshine on eyes. The retina could possibly get damaged. The cable should be periodically cleaned with cotton swab moistened with alcohol. The outer covering of the cable should be cleaned with mild detergent or disinfectant. The fiber optic cable shouldn't be placed close to the patient when it's connected to illuminated source of light. Heat generated could cause burn.

Instruments: Meticulous care should be drawn in mechanically cleaning all of the areas of all laparoscopic instruments. The handles are un-screwed, inserters taken out and the hollow sheath is cleaned with running water or syringe. Instruments are wiped dry gently and lubricated with silicone oil. Fundamental essentials vital steps before sterilization or disinfection of laparoscopic instruments. All metal instruments or part that may undergo sterilization using a steam autoclave should be handled in this way. Suction/ Irrigation tubes are thoroughly cleaned with running plain tap water before autoclaving them.

The telescope eye piece, light cable slot and it is patient end must be cleaned with tepid to warm water and the patient end, additionally with camera cleaner liquid. The ends of the telescope are responsive to heat; hence it ought to be sterilized with chemical sterilizer. Laparoscopic camera will be damaged by heat as well as repeated contact with chemical germicides. More within the irregular configuration from the surface of camera helps make the disinfection difficult and unpredictable. Therefore camera would be best given using barrier for example sterile plastic/ cotton sleeve to prevent contamination of operating field. They're priciest parts of equipment, hence should be handled with utmost care. Avoid crumpling of their lead and never use alcohol/ spirit to clean the camera head. Instead use camera head cleaner given by company or it may be simply cleaned with moist warm cotton.

Sterilization: It's understood to be complete elimination/ destruction of types of microbial life. It can be achieved with steam, gas or chemical sterilants. Disinfection the industry relative term means elimination of many or all pathogenic organisms except bacterial spores. It's split into three levels, high, intermediate and low. Higher level disinfection eliminates all organisms with exception of large quantity of bacterial spores. Intermediate level disinfection destroys all organisms except spores, most bacteria plus some fungi. Low level of disinfection can destroy most bacteria, some viruses plus some fungi. High level disinfection is accomplished by 2% Glutaraldehyde solution, a most widely used chemical sterilant used for higher level disinfection of laparoscopic equipments. The minimum recommended exposure time is Ten minutes, although some workers prefer and recommend for 20 minutes. It can sterilize the instruments only after ten hours of exposure. The life of the option would be generally 20-25 days. The potency and employ lifetime of the solution is decided more by use pattern and not strictly by time. The heavy use and inadvertent dilution or contamination will require early change of sterilant.It should be mentioned that no addition to described protocol is required to cope with HIV or hepatitis-B conta minated equipments. Both hepatitis and HIV virus are inactivated many physical and chemical processes much less potent than high level disinfection.

A brand new sterilization process, marketed as STERIS is available. Its active agent is per acetic acid, generally considered to be a stronger germicide which has hardly any harmful effects on optical instruments. It's the advantage of being a closed system and isn't susceptible to various factors responsible for lowering the efficacy of chemical germicide. Laparoscopic procedures are inherently complex. Many things will go wrong. The surgeon should be sufficiently familiar with the equipment to troubleshoot and solve problems. Table 1 gives a plan from the common problems, their cause, and suggested solutions. In conclusion, I would say that the pace of growth and development of diagnostic laparoscopy that was hitherto slow but steady over the last century has entered into an exciting era of laparoscopic surgery with invention of miniaturized video endoscopes, quality light source and successful performance of laparoscopic cholecystectomy. Credit goes to many scientists who steadfastly continued their efforts to create this science to the present state of art. The laparoscopic instruments are long, fine and insulated; hence, they're more susceptible to put on and tear. Gentle handling and thorough mechanical cleaning & lubrication just before sterilization/ disinfection increases their life and efficiency. A laparoscopic surgeon should have knowledge of instrument functioning, basic knowledge of supportive equipments and able to manage the problem shooting.