Instruments

The basic endoscopic instrument is either 5 mm or 10 mm in diameter and between 30 and 35 cm in length (Fig. 10) 853. Shorter and thinner instruments are available for paediatric work and some stapling devices are 12 mm or more in diameter. Originally the working ends were simple adaptations of a conventional design which were attached by a long shaft to an ordinary handle but many of these instruments were not very easy to use in practice. A plethora of new instruments have now been developed specifically for endoscopic work although the demand for a long, narrow, and circular design does impose quite severe limitations on the engineer.

 

In an open operation there is complete freedom to move in any direction but an endoscopic instrument has only 3 degrees of movement. The shaft can move in or out (translation), the tip can rotate about the axis (axial rotation), or the whole instrument can rotate around the point of entry (relative rotation). These limitations and the fixed relationship of the working ends to the handle in most surgical instruments can impose impossible demands on the surgeons' hands and a better arrangement is to allow the shaft of the instrument to rotate on the handle (Fig. 11) 854. There are also new designs of handle that can be used wherever they lie in the hand. Holding tissues in order to work on them is as essential in an endoscopic operation as it is in an open one but it can be difficult when the hinge of the forceps lies very close to the working end of the instrument. So far no entirely satisfactory design has been developed to overcome this problem but most of the available endoscopic graspers rely on refinements to the working surface of the blades usually by increasing the number or the size of the teeth in contact with the tissues. Conventional ratchets for securing an instrument to the tissues are almost impossible to release easily when they are positioned through an endoscopic cannula and screw threads on the handles (Fig. 12) 855 or a trigger grip are better alternatives.

 

The need to pass every instrument down a straight cannula imposes a limit on the curvature of the tips. This is a serious disadvantage when it is combined with the limitations on movement since it is commonly necessary to surround a structure before it is occluded and divided. It is true that the angle of approach can be infinitely varied if the curved tip can rotate on the shaft but it is still only possible to approach the structure from one general direction. A clever solution to this problem takes advantage of the memory that some metal alloys possess. The working end of the instrument is housed within a shaft of suitable diameter. When the end is pushed out of the housing the extension with the working end attached assumes a natural curve which makes dissection around a structure much easier. The end is then withdrawn into the housing before the instrument is removed.

 

In conventional surgery most instruments are designed for a single purpose and an efficient scrub nurse has always ensured that the surgeon has the instrument he needs immediately available. This is not so easy in endoscopic operations because every instrument has to be passed in and out of a cannula. This takes time and so there has been a move to devise instruments which do more than one thing. The most obvious adaptation has been the addition of diathermy to every suitable instrument so that both dissection and haemostasis can be accomplished without the need to change instruments (Fig. 13) 856.

 

Surgical technique

There are two fundamental parts to any surgical operation. Tissues and structures are first divided and are then joined back together again either in a different way or with part of the structure missing. In conventional surgery a scalpel and a pair of scissors are the basic tools for dissection and restoration is achieved with a needle and thread. Unfortunately neither the needle nor the knife adapt well to endoscopic work and alternative techniques have had to be developed.

 

Dissection

Dissection with a knife does not work in endoscopic surgery. Depth perception is difficult, the incisions always bleed and a sharp unprotected, and often invisible, blade could easily cause damage. Scissor dissection is not ideal either although it is sometimes essential. The tiny blades do not remain sharp for long particularly if they are also used for diathermy and the hinges become loose so that the tissues are not cut cleanly.

 

Gently tearing the tissues apart along the lines of least resistance either with a jet of water (aquadissection) or with a blunt instrument is useful. The dissection can be both accurate and precise because of the magnified image on the monitor even though the technique is not particularly attractive. Blunt instruments are safer when the tips cannot be seen and any small vessels can be occluded with diathermy as the dissection proceeds. Some oozing is inevitable and blood, which absorbs light, should be immediately sucked or washed away with warm saline solution. Even small amounts of blood can obscure the view during an endoscopic operation and so, whatever method of dissection is used, haemostasis is important.

 

Haemostasis

Coagulation

Coagulation of the tissues at the same time as they are divided is ideal and monopolar and bipolar diathermy, laser light, and ultrasound are all useful tools for dissection and adapt easily to the endoscopic environment. They minimize oozing and will stop haemorrhage from a visible vessel. When monopolar diathermy is used there should be a visible effect on the tissue the moment the current is passed (Fig. 14) 857. If nothing happens there may be a short circuit and therefore the possibility of damage to another structure. The most common error is contact between the metal of an instrument and an uninsulated cannula outside the field of view. Lasers are also potentially dangerous if improperly used. The staff must wear eye protection and backstops may be needed on the instruments to ensure that structures beyond the intended target are not damaged by the beam.

 

Bipolar diathermy will occlude vessels the size of the appendicular artery but anything larger than this requires some form of mechanical closure. It is not practical to tie a conventional ligature through an endoscopic cannula but slip knots which can be placed around a structure and then pulled tight in a single movement are useful. The original Roeder knot (Fig. 15) 858 was designed to be used with thick chromic catgut and there are modifications suitable for use with polyglactin and polydioxanone. All these knots are safe and reliable provided that they are properly constructed and correctly laid down. Every endoscopic surgeon should be able to tie them.

 

Clips

A more convenient method for occluding an artery or a duct is to apply a clip. Titanium metal clips are familiar and are available in multifire guns (Fig. 16) 859 especially designed for endoscopic work. Polydioxanone clips (Fig. 17) 860, which will eventually dissolve, have a locking mechanism which ensures that they are applied correctly. They can be difficult to close and have to be applied one at a time. Only one size of clip of either type is available at the present time.

 

Stapling

A vascular pedicle can be occluded and divided in one manoeuvre with a disposable stapler. The design is similar to the instruments used for intestinal anastomosis except that the staples are smaller and are placed closer together to ensure good haemostasis. Their use is limited by their cost.

 

Anastomosis

Endoscopic suturing requires time, constant practice, and considerable dexterity. Special ski needles are available (Fig. 18) 861 and the knots can be tied externally and tightened with a pusher or internally with instruments. Quicker and easier but more expensive are the mechanical stapling devices that are becoming available (Fig. 19) 862. Endoscopic adaptations of the larger stapling instruments which are in common use in conventional surgery are available although they are expensive. They will, in time, become the standard method for joining tissues together in an endoscopic operation.

 

Removing the specimen

Most, but not all, endoscopic procedures require the removal of a specimen at the end of the operation. Small pieces of tissue can be easily removed through a large cannula. Larger specimens are more difficult. Some can be reduced in size by removing the contents and then the specimen either through a cannula or through the incision when the cannula is withdrawn. Large solid specimens are more difficult still. A few can be extracted through a natural orifice which is opened during the course of the operation but most must be reduced to smaller pieces and removed through one of the cannula sites. The specimen is placed inside a tough plastic bag introduced into the body cavity (Fig. 20) 863. The bag is brought to the surface and the tissue is morcellated or liquefied with a special instrument within the bag inside the body. The pieces of tissue are removed or sucked away and the bag is then removed as well. The specimen is effectively destroyed so far as histological examination is concerned and suitable biopsies must be taken first.

 

Finally one of the cannula sites can be enlarged or a separate incision made specifically to remove the specimen. This obviously loses some of the advantages of the minimally invasive approach although the incisions are often smaller, more discreet, and less morbid than they would otherwise be.

 

Training the staff

Surgeons

Most surgeons are not familiar with endoscopic techniques but they can be used in every branch of surgery and in the future every surgeon will need endoscopic skills. Some initial training outside the operating theatre is useful for learning the basic manoeuvres that are needed. Flexible endoscopists are familiar with the two-dimensional image and the limitations of manipulation through an endoscope but everyone finds the reversed movement of endoscopic instruments as a result of the pivoting action of the body wall very strange to begin with.

 

Although more sophisticated training systems are now available, the most useful practice in our experience is to learn to peel a tangerine with scissors and forceps inside a box whilst watching the procedure on a television monitor (Fig. 21) 864. This requires a team of two people, one to hold the camera and the other to operate on the fruit. It is easy to extend the idea to include learning to sew, tying a knot, or placing a clip. Once the basic technique is mastered it is then a question of assisting an experienced surgeon at a number of laparoscopic procedures and later starting to do parts of an endoscopic operation under supervision as with conventional surgical training. Every operation should be recorded for it is then easy to review and reconsider any difficulties that have been encountered.

 

Anaesthetists

Anaesthesia for endoscopic surgery is little different to conventional anaesthesia for the same operation. Relaxation is needed for abdominal operations and the lung must be collapsed for procedures within the thorax. Excessive pressure within a body cavity will cause undesirable physiological effects but these are rare with the modern electronically controlled insufflators, although there is always the risk of a gas embolism. Some carbon dioxide will be absorbed during the course of a long operation but it is easily removed by increasing the ventilation rate. By its very nature there is less need for analgesia after an endoscopic procedure but it is worthwhile injecting bupivacaine around the small incision sites.

 

Theatre staff

Endoscopic procedures are popular with most theatre staff because everyone can easily see what is being done and there are obvious benefits for the patient. However, the scrub nurse can feel less involved than usual because there are fewer instruments to pass although the individual instruments often need particular attention. Hinge screws require regular tightening and the endoscope needs constant cleaning to ensure a clear image and there are many other similar little tasks so that an attentive and interested nurse will always make an operation run more smoothly.

 

Staff in the sterile supply department are involved too for the instruments are both delicate and hard to clean. They often contain fiddly little pieces which are essential for proper function but are easily lost when the instrument is taken apart. For example, trumpet valves must be oiled every time they are sterilized otherwise they will stick in use. Once again attention to detail can make all the difference in the operating theatre.

 

SPECIFIC OPERATIONS