Theatre practice

Chapter 9

Theatre practice

Before undertaking a surgical procedure, whether it is minor (e.g. blood sampling) or major (e.g. a bitch spay or an exploratory laparotomy), it is vital that you consider all the steps involved in aseptic preparation. Any technique that involves the breaching of the skin, which acts as the body’s primary barrier against the outside environment, must be carried out under sterile conditions. Even a simple injection risks the introduction of pathogens into the body, and when opening up a body cavity the risk of infection is far greater.

To ensure asepsis within the operating theatre, each surgical procedure should be classified according to the degree of infection (Table 9.1) and this should be taken into account when organizing the day’s operating list. To reduce the chances of breaking asepsis, always start with the clean procedures and progress through the operations, finishing with the dirty ones.

Every aspect of a surgical procedure must be prepared aseptically and this includes:

Although preparation of the surgical environment may be largely done by your nursing team, it is important that you, the veterinary surgeon, understand the principles behind this vital job. It takes very little disruption to any of the routine procedures to compromise asepsis, which may lead to wound breakdown, systemic infection, reduced surgical success rate and thus inevitably the reputation of the practice.

Preparation of the surgical environment

Surgical procedures are carried out within a dedicated operating theatre. The preparation of the patient and some dirty procedures (e.g. tooth cleaning) may be carried out in the preparation room. To ensure a high standard of asepsis, practice protocols should include a strict monthly, weekly and daily cleaning routine for the operating theatre and preparation room. This is almost always carried out by the nursing staff, but it is the job of the veterinary surgeon to make sure that the task is being carried out effectively.

It is not the brief of this book to describe cleaning protocols, but there are rules governing the use of the operating theatre that should be adhered to if asepsis is to be maintained:

1. The theatre should contain only the equipment that is strictly necessary for the surgical procedure and it should be removed afterwards.

2. Only personnel involved in the procedure should be present in the theatre and should remain within the sterile area to minimize the risk of cross contamination.

3. The surgeon should concentrate on the procedure and should not be talking excessively. The act of talking releases droplets full of bacteria.

4. Body movements should be restricted as much as possible to reduce air movement and the chance of contamination.

5. All personnel should understand that they are either sterile or non-sterile and there should be no cross contamination between the two.

6. Sterile and non-sterile equipment should be identified and grouped separately and kept a reasonable distance apart to reduce the risk of cross contamination.

7. Sterile tables are sterile only at table height; gowns are sterile only from mid-chest to waist; gloved hands are sterile only from the tips of the fingers to 2 inches (5 cm) above the elbow.

8. Always hold your sterile hands together above waist height and when passing another sterilized person you should pass back to back to avoid contamination.

9. All waste must be disposed of correctly and efficiently.

Sterilization of surgical equipment

Sterilization may be defined as the destruction of all micro-organisms including bacterial spores. It is much more effective than disinfection, which destroys or removes micro-organisms but does not destroy bacterial spores.

Everything that comes into contact with the surgical site must be sterilized prior to use. This includes all instruments, drapes, swabs and all the equipment used for the procedure (e.g. orthopaedic screws, plates, fixators, drill bits, urinary catheters, feeding tubes, etc.). If sterilization is not carried out properly there is a risk of introducing infection into the body and / or the wound, which may result in wound breakdown and / or systemic infection.

Sterilization can be achieved by various methods:

1. Irradiation – the use of gamma irradiation can be carried out only in a controlled environment and is not done in practice. Prepackaged items such as needles and syringes are sterilized in this way.

2. Heat – micro-organisms are killed by high temperatures and the different methods aim to raise the temperature as high as possible.

• Boiling water – this is the simplest form of sterilization, but it is not always the most reliable. Instruments may be sterilized in boiling water, but it must be kept at a rollicking boil for at least 10 minutes. It can be used when nothing else is available, but there is a risk of melting some plastic items and blunting others.

• Dry heat – using a hot air oven. Micro-organisms are killed by oxidative destruction of their protoplasm, but they are more resistant to this if there is a dry atmosphere. To counteract this a hot air oven is designed to reach higher temperatures of 150–180°C. If the temperature is below 140°C then microbial spores will not be killed in less than 4–5 hours.

    These ovens are used to sterilize equipment such as orthopaedic drill bits, glass syringes and other glass equipment, cutting instruments and powder and oil that cannot be sterilized in the presence of moisture. Fabric, plastic and rubber will be damaged by the high temperatures.

    The disadvantage of a hot air oven is that a long cooling period is needed before the instruments can be handled and the moment the door of the oven is opened there is a risk of contamination by airborne organisms. There is also a risk of burning yourself and for this reason they are not recommended by the Health and Safety Executive (HSE).

• Moist heat (steam) under pressure – this is the most common method in a practice. Under normal circumstances water cannot reach temperatures higher than boiling point before producing steam but if pressure is applied, the boiling point is raised and the temperature of the steam is higher. The moisture in the steam increases the permeability of the packs of instruments and drapes to heat, which then kills the micro-organisms.

a. Pressure cooker – simple form of an autoclave. Water is boiled in an enclosed space and the air vent in the lid is closed when all the air has been driven out. The pressure then builds up to 15 p.s.i. (≈107 kPa). There is a risk of trapping a layer of air under the steam and this may not reach sufficient temperatures to sterilize effectively. The system is manually operated so there is room for human error.

b. Autoclave – there are various designs the most efficient of which are vacuum assisted and incorporate a second cycle, which removes moisture and dries the load. Most are fully automatic with a choice of programmes and have fail-safe mechanisms.

Effective sterilization relies on loading the packs of instruments, etc. correctly, making sure that there is adequate space for the free circulation of steam. Instruments must be free of grease and protein to enable the steam to penetrate and the autoclave must not be overloaded otherwise there is a risk of blocking the inlet and exhaust valves.

3. Cold chemicals – these are not always very effective and it usually takes at least 24 hours to ensure adequate sterility. Instruments and other equipment are soaked in alcohol-based chemicals or glutaraldehyde. The method is sometimes used to sterilize needles and suture materials in a shallow dish ready for use in emergencies. Chlorhexidine may also be used, but it has poor activity against bacterial spores, fungi and viruses so this is really only a form of disinfection.

4. Ethylene oxide – this gas sterilizes by inactivating the pathogen’s DNA thus preventing its replication. The sterilizer is in the form of a plastic container fitted with a ventilation system. Items to be sterilized are placed in a sealed polythene bag with a gas ampoule, which is then snapped from the outside to release the gas that permeates through the bag. Sterilization takes 12 hours, followed by 2 hours ventilation and a further 24 hours for the gas to dissipate. The process is usually done overnight and the sterilizer must be used only in a well-ventilated area away from the working environment.

Most equipment can be sterilized in this way, but the limiting factor is the size and shape of the sterilizer. It is usually used to sterilize things that may otherwise be damaged by heat (e.g. fibreoptic endoscopes, plastic catheters, anaesthetic tubing and optical equipment).

Monitoring sterilization

It is essential that sterilization is carried out effectively and this must be constantly monitored. There are several different methods of monitoring and it is important to select a method that is appropriate to the type of sterilizer used within your practice. If you do not then false results may be obtained.

• Chemical indicator strips (TST strips) – placed in the centre of the pack and change colour when the correct temperature, pressure and time have been reached. It is important to select the correct strip for the autoclave cycle. They are also used to monitor ethylene oxide sterilizers.

• Browne’s tubes – small glass tubes filled with orange liquid that turn green when the correct temperature is reached for the correct amount of time. Used in autoclaves and hot air ovens.

• Bowie Dick tape – beige-coloured tape impregnated with a chemical strip that turns brown when it reaches a temperature of 121°C. Used to seal packs of instruments or drapes, but is of limited value as it does not ensure that the temperature has been maintained for a set time. Used in autoclaves.

• Spore tests – strips of paper impregnated with bacterial spores (usually Bacillus stearothermophilus) are placed within the load. After sterilization, the paper strip is placed on a culture medium and incubated at room temperature for 72 hours. Lack of growth indicates effective sterilization. It is an accurate method, but delay in culture results is a disadvantage. Used in autoclaves, ethylene oxide and hot air ovens.

• Thermocouples – electrical leads with temperature sensitive tips. The tips are placed within the load and the leads are passed out of the autoclave door and attached to a recording device. The temperature is recorded at intervals during the autoclave cycle.

• Ethylene oxide tape – similar to Bowie-Dick tape, but the lines are green and change to red on exposure to the gas.

There are many types of packaging used for sterilizing surgical equipment and the choice depends on factors such as cost, method of sterilization and personal choice. All sterilized packs should be labelled with the contents (e.g. spay pack), the date and the name of the person responsible. It should not be assumed that once a pack is sterile it will remain so forever – if the pack has not been used within 3 months it should be resterilized.

Preparation of the surgical site

The skin and hair of the patient are the greatest potential sources of wound contamination because it is never possible to remove all micro-organisms; however, careful preparation of the surgical site following established practice protocols will minimize the risk. Much of the preparation of the surgical site may be carried out by the nurse, but in small practices it may be done by the veterinary surgeon.

Procedure: Clipping the site

This should be carried out within the preparation room to minimize contamination of the operating theatre.

1. Action: The patient should be anaesthetized, and placed in the correct position for the surgical procedure.

    Rationale: The patient will not move, thus making the task easier. If the patient is considered to be an anaesthetic risk, clipping prior to induction will reduce anaesthetic time.

2. Action: Ensure that the clippers are clean, sharp and in good working order.

    Rationale: Poorly maintained clippers are more likely to nick the skin and cause ‘clipper rash’.

3. Action: Select the site for the surgical incision and clip with the grain of the hair first and then repeat against the grain.

    Rationale: Removal of long, thick hair is easier with the grain. Clipping against the grain achieves a closer clip.

4. Action: Clip at least 5–15 cm beyond the line of the incision.

    Rationale: This allows the surgeon to extend the incision if necessary. Do not clip unnecessarily as this may annoy the owner.

5. Action: Make sure that the finished edges are neat.

    Rationale: Owners are not impressed by untidy clipping.

6. Action: If clipping around an open wound or close to the eyes, apply an appropriate water soluble gel to the area before clipping. Wipe away the gel before cleaning the site.

    Rationale: This will trap tiny hairs, which may act as foreign bodies in an open wound or cause irritation in the eye.

Procedure: Cleaning the surgical site

This is carried out in the preparation room until step 8, when you should move to the operating theatre. This is done to minimize contamination of the operating theatre.

1. Action: Put on a pair of surgical gloves – they do not need to be sterile at this stage.

    Rationale: This will protect the patient’s skin from your hands and will protect your hands from the antiseptic skin scrub.

2. Action: Use an appropriate skin scrub (e.g. chlorhexidine or povidone iodine) at the correct dilution.

    Rationale: Always read the manufacturer’s instructions. Both of these have disinfectant and detergent properties and are safe to use on skin (i.e. they are antiseptics).

3. Action: Use lint free swabs.

    Rationale: They will not contaminate the site with minute threads or particles.

4. Action: Select one hand to be your ‘clean’ hand and the other as your ‘dirty’ hand. If you are right-handed use your right hand as the ‘dirty’ hand as this hand does the majority of the action.

    Rationale: If you can remember to do this it minimizes contamination of fresh swabs and the cleaned area.

5. Action: With the ‘clean’ hand, pick up a fresh swab and pass it to the ‘dirty’ hand. Dip it in the bowl of skin scrub solution and, starting at the incision site and working with a circular motion, wipe the skin towards the edges of the clipped area.

    Rationale: By moving with a circular motion you should not miss any part of the site. Working from the centre towards the outside ensures that you do not bring dirt from the coat to the surgical site.

6. Action: Once the edge is reached then discard the dirty swab.

    Rationale: To avoid recontamination of the cleaner area.

7. Action: Select a fresh swab with your ‘clean’ hand, pass it to your ‘dirty’ hand and keep repeating the process until the used swab is not discoloured.

    Rationale: This indicates that all visible dirt has been removed. Take care not to return to the centre of the area once it is clean.

8. Action: Include the hair at the edges in your cleaning.

    Rationale: This removes debris and flattens the hair. Do not make the hair too wet as this may promote ‘strike-through’ (i.e. the passage of micro-organisms, suspended in water, through the cloth from inside to outside thus recontaminating sterile areas) or hypothermia.

9. Action: Transfer the patient to the operating theatre and position for surgery using appropriate restraints if necessary (e.g. ties).

    Rationale: The site will now have been recontaminated.

10. Action: Wearing sterile gloves and using sterile swabs and water, repeat the scrub procedure as described before.

    Rationale: Sterile equipment is used in the clean theatre to maintain an aseptic environment as much as possible.

11. Action: The final skin preparation is carried out by a member of the surgical team using sterile swabs held in Rampley sponge-holding forceps. An alcoholic solution of a skin disinfectant is applied and left to dry on the skin.

    Rationale: The alcohol solution will remove any remaining detergent and provide residual bactericidal activity. Do not apply to open wounds or mucous membranes. Do not use diathermy if alcohol solution has been applied.

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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Theatre practice
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