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CHAPTER 31
Key Principles of Laparoscopic Surgery
The need for staff educated and trained specifically in minimal access surgery techniques and skills is well recognised and documented.
This chapter aims to provide an insight into the key principles of laparoscopic surgery to provide specific knowledge in relation to patient care and safety by understanding the technical aspects of the equipment and instrumentation required.
The development of laparoscopic surgery is inextricably linked with advances in the field of medical imaging, instrument development and with the skills of the surgeon and the theatre team.
In 1806, when Philip Bozzini built an instrument which allowed him to look into the human body, lit by a candle, this was the start of the development of endoscopy, although he was years ahead of his time. Still relevant today in laparoscopic surgery is the use of carbon dioxide for insufflation discovered by Richard Zollikofer in 1920 and the rigid rod lens system developed by Harold Hopkins in 1953, which revolutionised videoscopic surgery (Mishra 2011).
These developments have allowed patients to have surgery without the need for large abdominal wounds, which decreases postoperative pain and potentially disfiguring scars. The ability to offer a laparoscopic approach to a patient allows a shortened postoperative recovery in hospital and convalescent time at home. In conjunction with this the development of endoscopic stapling devices has advanced colorectal and bariatric laparoscopic surgery.
Preparing the Environment
Experience has shown that until the team is familiar with the extra equipment and checks required for laparoscopic surgery, additional staff may be required. For theatre practitioners there appears to be much more to do at the beginning and end of a session and less during each procedure There is always the possibility that conversion to open surgery may be necessary, and therefore any additional instruments should be readily available and a full-scale swab and instrument check initiated at the commencement of the laparoscopic procedure.
Although each team will determine its own set-up depending on personal preference and theatre size, some general principles can be identified. The use of specially designed stacking systems for equipment is strongly recommended as connections can be maintained between sessions, equipment is positioned at the appropriate height, access is eased and cabling from the unit to the power source is reduced. To maximise function of the stack and for all the team to get the best views of the screen, careful positioning of the equipment is essential.
All equipment must be functioning and positioned correctly prior to commencement.
The insufflator should be checked to ensure there is adequate CO2 in the cylinder, that it is correctly connected, has been turned on and that the insufflator performs a self-calibration test.
The monitors are positioned on either side of the patient such that the surgeon, assistant and scrub practitioner have a clear, unobstructed view. The surgeon will also need to see the insufflator display panel. Instrument trolleys and stacks, suction equipment, leads, cables and tubing need to be arranged to facilitate access by the theatre team, and to ensure that they do not become tangled or damaged during draping of the patient.
Attention to the placement of technical equipment and room preparation needs to be considered in conjunction with the usual preoperative preparation of the patient.
In minimal access surgery, the positioning of the patient is dependent upon the operation being undertaken. General principles identified include the use of an X-ray translucent table, and a secure patient position.
Medical Imaging
There are five main components to the imaging system:
- video camera and control unit
- scope
- light source, fibreoptic cable
- video monitors
- video recorder/printer.
Video camera and control unit
The video camera and control unit consist of a small lightweight camera head, cable and camera control unit with the following features:
- Lens
- Video imaging chips: These are one or three charged coupled devices (CCDs) covered in silicone cells (pixels) that are light-sensitive. They emit electronic signals via the camera cable to the camera control unit (CCU) that transforms information into a video signal, which is transmitted to the monitors. Colour, detail and image sharpness (resolution) are governed by the number of imaging chips. A three-chip camera provides greater resolution and a more accurate and natural colour, but is more expensive. Single-chip cameras, however, do now have improved resolution due to advanced electronics in CCDs and also in CCUs due to improved signal processing.
- Auto shutter: This controls the amount of light the camera detects at the surgical site. Shutter speed is changed automatically to reduce flare caused by metal reflective instruments passing through the field of view.
- Focus: This moves the lens elements in the camera relative to the CCD to sharpen the image (it can be manually controlled using a focus ring on the camera body).
- Light gain switch: This helps the camera compensate for low light situations by boosting the video signal amplitude. Unfortunately, the gain switch also boosts unwanted video signal ‘noise’.
- White balance: This creates a fixed point of reference for all the other colours viewed by the camera which compensates for the type and condition of light source being used.
- Orienting feature: This enables operators to keep the image in the correct plane on the monitor.
Scopes
Video endoscopes are designed to transmit the image to a monitor. Within the scope is a negative or objective lens which creates the image at the operative site. A delicate system of rod-shaped glass lenses which are positioned end to end (Hopkins rod lens system) transmit the image along the length of the scope to the ocular lens which magnifies the image. Wrapped around these delicate lenses are thousands of light-carrying fibres, transmitting light to the operative site.
Scopes have different diameters, 5 and 10 mm, and also different angles of view – 0, 30 and 45 degrees.
Warming the scope to body temperature before insertion will minimise fogging of the distal lens. Anti-fog chemicals can also be used or scope-warming devices. The objective lens needs to be cleaned during the procedure if it becomes soiled. Never use abrasives; warm saline and proprietary solutions may be used.
Continuous vision of the operative field is essential, it is particularly important to keep all instruments within sight to avoid accidental damage to tissue. This is particularly pertinent to port insertion and electrosurgery activation.
Light source and fibreoptic cable
The ideal light source emits a light with consistent intensity and balanced colour temperature. Other features include:
- auto and manual control of light output
- infrared filter (heat dissipation)
- standby mode to prolong lamp life
- hours meter for lamp life measurement.
There are two principal lamps used in laparoscopic light source units: metal halide and xenon. The light source and cable produce an intense light beam. The light should be on its lowest setting or switched off unless the laparoscope is in use (standby mode).
Careful handling of the hot end of the light cable reduces the chance of burns to staff or the patient. Retinal damage can be caused by looking directly at the light beam.
Video monitors
Signals are processed by the CCU and displayed via video cables on the monitor. Monitors should be high resolution, medical grade to maintain the quality of the video image and be fully compatible with the imaging devices in use. Most systems now have high definition (HD) monitors.
Note: It is important to be familiar with the sequence of the colour bars on a correctly connected RGB system; it is white, yellow, cyan, green, magenta, red and blue.
Video recording/documentation equipment
The procedure may be recorded by attachment of the appropriate cables to the CCU.
Video/Imaging Systems
Recent developments which have improved image and the integration of systems include the following (Leeds Institute for Minimally Invasive Therapy 2002):
- digital camera systems, giving improved image quality and the ability to enhance images while maintaining high quality
- interfaces with other digital equipment and larger images (panoramic view)
- ‘intelligent’ light sources
- scope recognition
- voice operation (control of light and camera properties without compromising sterile fields)
- digital video recorders (DVR)
- flat screen display devices using plasma technology
- digital printers that can be interfaced with computers
- laparoscopic ultrasound (LYNX) that can be mixed with camera image and displayed as a PIP (picture in picture).
Laparoscopic Instrumentation
Instruments may be described as either ‘access’ or ‘operating’ instruments, according to their use.
Most instruments are available as single patient use (spu) or reusable multiple patient use (mpu) (MHRA 2001). The majority of mpu instruments are ‘take-apart’, to help with the process of cleaning and decontamination. Prior to use, all instruments need to be checked to ensure correct assembly and that each one is functioning as designed. It is also essential to check that insulation is intact, to prevent inadvertent burns to the patient or surgeon.
Access
There are three main methods to gain access to the abdomen: open or closed techniques and under vision.
Veress needle
A Veress needle is used to introduce carbon dioxide gas into the abdomen prior to port insertion. It consists of a blunt inner tube with a spring-loaded outer sheath with bevelled sharp needle and a luer lock at the proximal end for attaching insufflation tubing. The standard diameter of the needle is 2 mm and they are available in different lengths for obese patients and as a spu or mpu.
Instruments
Laparoscopic instruments need to do much the same as open instruments but have to be designed for tissue handling at depth, and through the ports.
There is a wide range of forceps and graspers, some with generic uses and others designed for a specific purpose. Instruments can be either single action, where only one side of the instrument jaw moves, or double action, where both sides move. A choice of handle for most grasping forceps is available – pistol grip or in-line – with the option of a ratchet mechanism which locks the handle, exerting a constant pressure on the tissue being held. The handle may well be a mpu and the instrument spu; this type of instrument is termed a reposable instrument. Any instrument that is to be used with diathermy needs to be insulated. The ergonomics of the instrument need to be designed for ease of use and operator comfort.
Scissors should be checked for blade alignment and that they are sharp if mpu. Needle holders need to be able to grasp and firmly hold a metal needle. They are designed with jaws made of tungsten carbide to prevent the needle rotating.
Care and Handling
The costs associated with the purchase of laparoscopic instrumentation are high and most purchasers have a limited budget. Therefore it is essential that the users are aware of the manufacturer’s recommendations for cleaning and sterilisation.
The complexity of laparoscopic instrumentation and the way it is used can make it very difficult to clean thoroughly. All theatre personnel involved in laparoscopic surgery should be aware of the instruments in use in their department and understand the assembly, disassembly and sterilisation method required.
Perioperative staff should be familiar with all technical equipment, products and instruments used. Laparoscopic instrumentation is constantly changing and improving. Perioperative staff need educational resources and product information with instructions that are concise, clear and easy to follow.
The decontamination of reusable instrumentation for laparoscopic surgery needs well-trained staff. Instrument design should allow easy dismantling and rinsing of internal parts. Correct handling and maintenance processes need to avoid damage to the instruments. Protective transport and effective containment reduces the potential for damage to fragile laparoscopic instruments.
Reusable instruments are an economical option, however disposable parts on reusable tubes and handles offer an alternative to complicated or easily damaged working tips (e.g. scissors blades that easily blunt).
Instrument Handles
With instruments that ‘take-apart’ there are various handles available. Non-ergonomic positioning of the hand and fingers can lead to pressure areas, nerve irritation and rapid fatigue for the surgeon over a period of time.
Ports
A port is a tubular device (cannula) providing access to the internal surgical site, facilitating instrument access via the lumen. Common features include; a stopcock/tap to allow insufflations, a tubing attachment, a seal or valve preventing loss of pneumoperitoneum. Ports are available in a variety of diameters and lengths. Selection is dependent on the surgery being undertaken and individual body dynamics.
Disposable, reposable and reusable versions are available. A variety of trocars are available to enable safe insertion of the port. Trocar selection is dependent on the chosen method of access and on surgeon preference.
Initiating and Maintaining the Pneumoperitoneum
In order to expand actual or potential body spaces to facilitate surgery, carbon dioxide is used because it is cheap, does not support combustion, does not distort the image and is readily soluble and excreted via the lungs.
When initiating closed pneumoperitoneum, using the Veress needle method, it is important to ensure that the scrub practitioner is familiar with the assembly and safety checks necessary on the Veress needle. The procedure is as follows:
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