General operative principles

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23 General operative principles

This chapter details many aspects of safe surgical practice common to all specialties.

Minimisation of infection

Fundamental to keeping bacterial contamination to a minimum is theatre design and the concept of asepsis (Box 23.1). Operating theatres are divided into zones including the transfer zone, the clean zone, the sterile zone and the disposal zone. The ventilation system of the operating theatre permits temperature control and humidity, air filtration to remove microorganisms, movement of air from clean to less clean areas and rapid and non-turbulent air change. Twenty to thirty changes per hour is usual. Infection control is achieved by sterilisation of instruments and equipment, skin preparation and draping of the patient, preparation and clothing of the operating team.

Box 23.1 Infection control

Sterilisation – a process that involves the complete destruction of all microorganisms, including bacterial spores

Disinfection – reduces the number of viable microorganisms but does not necessarily inactivate viruses and bacterial spores

Cleaning – a process that physically removes contamination but does not necessarily destroy microorganisms e.g. hand-washing (see p. 335).

Preparation of the patient’s skin

Half of all wound infections are caused by bacteria resident on the skin. At the start of the operation, a wide area of skin is cleaned with povidone-iodine or chlorhexidine solution. Excess body hair is most safely removed by clipping rather than shaving as this can cause minor nicks and scratches in the epithelial surface, bringing bacteria to the surface and increasing the incidence of wound infections. The area of the operation is isolated using surgical drapes.

Scrubbing up

This was formerly a ritualised process but it is now known that brisk scrubbing of the skin can cause micro-trauma to the epidermis and increase the bacterial count. An initial scrub of the fingernails at the start of the operating list is all that is required and this should take 3–5 minutes. All jewellery is removed. The fingers, hands and forearms are cleaned using a medicated detergent such as chlorhexidine gluconate (Hibiscrub) or povidone-iodine (Betadine). Gowns and gloves are donned with a closed technique. Newer gown materials such as GoreTex or close-woven polyester have been developed to overcome the problem of permeability to bacteria but these are expensive. Impervious gowns are essential, however, when operating on high-risk patients. All gloves are now talc-free.

Infected and other high-risk patients

‘High-risk’ patients, i.e. at high risk to the surgeon and operating staff, comprise patients with hepatitis B or C or HIV. Measures to prevent contamination include impervious gowns and drapes, wearing a plastic apron under the operating gown if any contamination is anticipated, double gloving, eye protection, the avoidance of hand-held needles and use of stapling devices for anastomoses to reduce the risk of needle pricks. It should not be forgotten that prions are a potential source of contamination and, where possible, disposable instruments are now used. In addition, operating room discipline, for example passing needles or scalpels between scrub nurse and surgeon in a transit dish to prevent injury through hand to hand passage, and very careful disposal of all contaminated material at the end of the procedure into plastic bags for incineration is essential. Immunisation against hepatitis B should be mandatory for all healthcare workers exposing themselves to these risks.

The common positions for operations are listed in Table 23.1. Careful positioning is important, not only for access to the operating site, but also for prevention of nerve injuries which can occur as a result of traction pressure; for example, the brachial plexus and ulnar nerve, radial nerve and common peroneal nerve may all be damaged by careless positioning of the patient.

Table 23.1 Common positions for operations

Position Use
Supine Suitable for many operations
Prone Back surgery
Trendelenburg
Supine, but patient tilted 30–40° head-down Pelvic organs; small intestine moves out of the way with gravity
Reverse Trendelenburg
As Trendelenburg but tilt head-up Upper abdominal organs
Lloyd-Davies
As Trendelenburg but with legs abducted and hips and knees slightly flexed and legs in rests Combined procedures involving abdomen and perineum (usually on distal large bowel)
Lithotomy
Supine, hips and knees fully flexed, feet in stirrups or straps Access to anal and perianal regions and external genitalia, vagina and uterine cervix, urethra and bladder (endoscopic)
Lateral
Extension on right or left side with uppermost arm raised above and in front of head. Centre of table may be angled (broken) to improve access Operations on kidney and in chest
Bowie
Prone with flexion at hips Access to perianal area

Wound closure

This can be achieved in a number of ways:

• suturing

• adhesive tape

• staples/glue

• plastic surgery procedures to close defects which cannot be treated with the above methods, e.g. skin grafting, flap transfer (see Chapter 18).

Needles

• Straight needles are hand-held and are typically used to close skin edges in a subcuticular technique

• Curved needles are usually held in a needle holder but very large needles exist for hand-held use. Curved needles can have cutting or round-bodied points. Cutting edges are designed for closing wounds and can penetrate fascial layers. Round-bodied needles are used for suturing bowel, vessels and nerves, and are the needles used in microsurgery. They are designed to push tissues aside instead of cutting through them.

Sutures

There are two types, absorbable and non-absorbable.

Absorbable

• Broken down by the body by hydrolysis

• No foreign material left in wound once absorbed

• Reduced wound infection rate as organisms not trapped in suture material indefinitely

• May be absorbed too quickly before wound has regained tensile strength

• If broken down too quickly in infected wound, may lead to secondary haemorrhage

• Examples include Vicryl, Dexon, PDS.

Non-absorbable

• Retains strength for long periods

• Natural (silk, metal) and synthetic (nylon, Prolene, Ethibond) materials are available

• Promotes foreign body reaction and organisms can become trapped around braided suture materials for long periods of time. Infected sutures often have to be removed for infection to clear completely

• Synthetic monofilament sutures are ‘slippy’ and harder to handle and tie than the natural braided versions. However, they slide through tissues easier than their braided counterparts, causing less local trauma to tissues.

Staples

• Skin – to close wounds quickly

• Intestine – useful for anastomoses in anatomically difficult locations

• Lung – gives an airtight staggered row of staples in lung resection.

Tapes

These are adhesive strips of tape suitable for minor wounds of the skin. They avoid the puncture marks that can be left by sutures. Adhesive strips are particularly suitable for children, who may be anxious about suture removal.

Adhesives

Tissue glues are also suitable for minor skin wounds and are well tolerated by children as local anaesthetic infiltration is avoided. Tissue glue is not suitable for oozing wounds, and mistakes in alignment of the wound edges cannot be easily rectified.

Dressings

• Protect wound from further contamination

• Absorb discharge from the wound

• Enable the application of substances which may help reduce infection and slough.

After 48 hours, sutured wounds can often be left exposed without undue risk of further contamination. Open wounds left to heal by second intention require continued dressings until healed.

Many different substances have been added to dressings in an attempt to accelerate healing or aid debridement. Except in a few specific circumstances, there is little evidence to show that these specialised and often expensive dressings are any better than attentive and thorough surgical and nursing care.

Access and common incisions

The correct incision must be made to allow adequate access to the operative field. Important considerations for incisions include sound healing and minimal pain during recovery with minimal complications and a satisfactory cosmetic result. Skin incisions, if possible, should follow the skin cleavage lines as described by Langer (Fig. 23.1). Abdominal incisions are shown in Figure 23.2.

image

Figure 23.1 Skin cleavage lines (Langer’s).

image

Figure 23.2 Types of abdominal incision.

The closure of incisions is important and should be meticulous. Many incisions can be closed with a mass closure employing strong, slowly absorbable sutures. Many surgeons prefer to close wounds in layers.

Drains

Drains are inserted to evacuate established collections of pus, blood or fluid. They range from simple wicks to low pressure suction applied to tubes. There is controversy concerning their use, with advocates maintaining that drainage of fluid collections removes potential sources of infection, guards against further fluid collections and alerts the surgeon to the presence of leaks or haemorrhage. However, the presence of a drain may increase the chance of infection and can cause damage to nearby structures. In many cases, they are ineffective after a few hours. The different types of drain in common use are shown in Figure 23.3. Most drains in modern surgical practice are closed in nature.

image

Figure 23.3 Different types of drain.

Minimal access surgery

The recent proliferation of minimal access surgery techniques has meant that many procedures that were otherwise performed by the open method can now be performed with this technique. The advantages proposed are that the wounds are less painful, surgical tissue trauma is minimised, physiological effects from open operations, for example cooling, excessive handling and drying of internal organs, are avoided. Postoperative recovery is quicker and there is a reduction in complications related to the wound (dehiscence, incisional hernia and infection). There is also a reduced risk of contact with the patient’s blood and postoperative complications such as chest infections and deep vein thrombosis.

Disadvantages of these techniques concern the time that they take to perform, which has a knock-on effect on scheduling and costs, and the special technical expertise necessary to perform them safely. Pneumoperitoneums may compress the diaphragm and lung bases, causing postoperative hypoxia. Not all patients are suitable for this type of procedure and there is a risk of gas embolism although this may be small. Precise control of bleeding is more difficult to achieve but is possible. The extractions of organs may be difficult. Nevertheless, laparoscopic procedures are commonly used for cholecystectomy, oesophageal reflux, gastro-oesophageal malignancy, colonic malignancy, pancreatic malignancy, splenectomy and nephrectomy. Further advances will undoubtedly be made. As part of the informed consent process for any patient undergoing these techniques, it should be emphasised that there is always a risk of converting to an open procedure for technical reasons, anatomical reasons or pathological reasons which the patient must be made to understand.

Haemostasis

The three main techniques used in stopping haemorrhage are compression, ligation and thermal coagulation. Compression via packing is particularly useful if there is widespread oozing. Ligation may be achieved by the use of haemostats and ligatures, either absorbable or non-absorb-able. Ligation may also be achieved by the use of stainless steel clips carried on special forceps. Thermal coagulation is achieved by the use of diathermy (Fig. 23.4). The electrical current pathway is either from the point of application through the body of the patient to a large area of contact plate and thence to earth (unipolar) or between two points of the instrument (bipolar). Small blood vessels can be precisely dealt with by either technique. A newer development is the employment of bipolar energy and mechanical compression to reliably seal vessels up to 7 mm in diameter (LigaSure™).

image

Figure 23.4 (a) Bipolar diathermy. (b) Unipolar (monopolar) diathermy.

Tourniquets

Many orthopaedic operations on the limb are performed in a bloodless field achieved by the use of a pneumatic tourniquet. Lower pressures are used in patients with little subcutaneous fat and do not exceed 250 mg of mercury for upper limbs and 500 mg of mercury for lower limbs. Reductions in pressures are made for children. The duration of its application must be kept to a minimum by careful planning. One hour is the customary maximum tourniquet time. If the operation is likely to last more than image hours, the tourniquet should be released for 10–15 minutes and bleeding controlled by elevating the limb. Before closing the wound, the tourniquet should be released to ensure that meticulous haemostasis is achieved on completion of the operation. Elevation of the limb for up to 5 days following tourniquet procedures helps to prevent postoperative swelling. Tourniquets should not be used if patients suffer from peripheral vascular disease or sickle cell disease.

Fluoroscopy

Many operative procedures require the use of fluoroscopy during the procedure (e.g. an on-table cholangiogram to check arterial patency or to confirm the position of pins and plates in orthopaedics). The same strict safety measures must be taken in terms of protection of the patient and staff with the use of these techniques and thorough understanding of X-rays is mandatory. The patient and staff should be shielded whilst the examinations are being performed. Trained radiographers must control the delivery of the X-rays to the field. Exposure must be the least possible that achieves the desired image. A record must be kept in the patient’s notes of the procedure. In the UK, the application of ionising radiation is tightly monitored and subject to regulations set out in The Ionising Radiation (Medical Exposure) Regulations, 2000 (IR(ME)R).

Lasers

The use of laser technology is limited in surgery, although it has a larger place in endoscopic management, for example ablation of gastrointestinal tumours, and in plastic surgery. Precautions must be taken to protect the patient and staff, particularly with respect to prevention of eye damage. The energy generated must be strictly controlled.

Laser treatment for varicose veins is replacing conventional stripping techniques.

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