General operative principles

Published on 11/04/2015 by admin

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Last modified 11/04/2015

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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

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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