Operating theatres are busy rooms – particularly in an emergency – so it is important for medical personnel to know that the room they are about to use is clean and the equipment sterile. Ensuring that operating theatres and storage rooms are as sanitary as possible is critical to patient safety, and the way in which this is achieved is a constantly evolving process that is regularly reviewed and altered.

The first thing to consider is the room itself; it should be unsoiled, uncontaminated and dust-free. It should also be minimalistic as this will be easier to clean, and there will be nowhere for unwanted germs and microorganisms to hide. But the room itself is unlikely to be sterile, says Trevor Garcia, director of education at the UK Institute of Decontamination Sciences, a professional body that manages risks associated with Health Care Acquired Infections (HCAI) in medical devices reprocessing.

“Neither operating rooms nor storage areas will be sterile, so they need to be kept as clean as possible with regular cleaning regimes, filtered air-conditioning and restricted access,” Garcia says. “The room should have all walls and ceilings painted or covered in an easily cleanable product that withstands chemical cleaning, and floors should be easily cleanable and with any joints welded to ensure a continuous surface. It should also have sealed windows and light fittings.”

And what applies to the operating room also applies to the storage areas. These are home to sterilised equipment and should therefore be easy to keep clean, with access restricted only to those working in the area.

Air should be as clean and dust-free as possible. Storage rooms should be well ventilated with controlled temperature and humidity levels in line with the packaging material manufacturers’ recommendations, as too much or too little moisture in the air can affect the integrity of packaging and labels, rendering once-sterile equipment unsterile.

Shelving, other storage units and furniture should be manufactured from robust, non-linting materials – aluminium, stainless steel or chrome-plated materials, for example – which are easy to clean, Garcia continues. It should be solid to avoid potential damage to wrappers, and shelves should be clearly labelled and a location plan easily accessible to direct personnel in an emergency. Commercially sterilised packs should be stored separately to those produced in-house, and outer cardboard cartons should not be permitted in the processed goods store as these can harbour dust and bacteria in their grooves.

Too much or too little moisture in the air can affect the integrity of packaging and labels, rendering once-sterile equipment unsterile.

Closed shelving within the storage area might be the most preferable way to store equipment as this will help keep them protected from outside influences, but open shelving is actually the most common. It is economical, easy to keep clean and allows easy access to equipment. But it doesn’t provide much protection to the equipment and all sterile items must be stored away from the walls and floor to avoid temperature changes and moisture, both of which can affect the integrity of the equipment’s packaging.

“When placing packs on shelves either directly or in designated containers, the ‘first in, first out’ principle should be followed,” says Garcia. “And handling of sterilised packs should be minimised to avoid damage,” as contamination of instruments is believed to increase the more they are handled.

First in, first out

The ‘first in, first out’ principle – or date-related method – is the most commonly used when it comes to storing sterile items. Much like stock rotation in a supermarket, items sterilised first are used before those sterilised later to ensure a constant flow of treated items. Safe storage times vary with the porosity of the wrapper and the storage conditions; any medical or surgical instrument which has been sterilised should not be used after its expiration date, or if the package has become wet, torn or punctured.

However, many facilities have begun to switch to an event-related method of storage, which recognises that a product should remain sterile until an event – a torn or dropped package, for example – causes contamination. Even if event-related packaging is used, it is recommended that each package still includes the date of sterilisation and that events are specifically defined so staff know whether it is safe to use an item or not, or whether it needs to be resterilised.

Garcia says that the debate regarding event-related sterility and date-related sterility is interesting: “I think event-related sterility can be managed through the instructions supplied by the manufacturer of the medical device, such as a statement on the label saying ‘store within these parameters’; if they are exceeded or not met then the product should be considered unsterile, or if the packaging is damaged then the product must be considered unsterile,” he says.

“If you only use event-related sterility, some devices may have been manufactured with materials that will degrade over a period of time, in which case an ‘event’ may not be the reason the device is unsterile: it is the materials in that device which may have deteriorated to a point that makes it unsafe, so time is the important part,” he adds. “Also, packaging material, even if stored in ideal conditions, will at some point in time no longer be able to act as a microorganism barrier. So, again, the date-related method may be necessary.”

Tracing the origins

The next thing to consider is where the sterilised equipment has come from. It will have either been supplied directly from the manufacturer, or been used in surgery. Either way, before it can be considered ready for use or placed in sterile storage, it must go to a hospital central processing unit to be decontaminated. This cleaning and disinfection process aims to protect patients from infections while minimising risks to staff and preserving the value of items.

A sterilisation and decontamination unit might clean between 100 and 150 sets of instruments daily – each with almost as many pieces – so each item has a tracker tag allowing their progress through the sterilisation process to be monitored. When it is received in the unit, it is scanned, and, as it is worked on, its record is updated to allow staff to pinpoint it if there is a query. Once sets have been washed, they are checked, reassembled and packaged.

This step raises an important question: what should the sterile equipment be packaged in? It needs to be a wrapper or container that allows penetration of the sterilisation agent, and which will maintain this sterility until the equipment is required. The packaging material should be designed for the type of sterilisation process being used, and for the items being sterilised. Following sterilisation, equipment needs to remain wrapped until required, and be kept in an enclosed storage area away from general traffic in a way that maintains the integrity of the packaging.

But what about the sterilisation process itself? Reliable sterilisation depends on the contact of the sterilising agent with all surfaces of the item to be sterilised, and the choice of agent depends on the nature of the item. Use of an autoclave – which uses moist heat under pressure to thermally destruct microbial life – is most widespread, but if an item is heat or moisture-sensitive, ethylene oxide is used. Ethylene oxide interferes with the normal metabolism of proteins within the microorganism and with its reproductive processes, causing cells to die. Other methods could include using dry heat, microwaves and ionising radiation, formaldehyde gas, ozone gas or hydrogen peroxide plasma.

Monitoring the sterilisation process is essential; all sterilisers have gauges, thermometers and timers or recorders to monitor their function, and many have alarm functions that become active if the process fails. Chemical indicators on equipment packaging – tapes or labels with colour-changing ink, for example – can verify whether sterilisation has taken place and help differentiate the sterile equipment from the non-sterile. If it fails to show that sterilisation has occurred, the equipment should not be used.

Some devices may have been manufactured with materials that will degrade over a period of time, in which case an ‘event’ may not be the reason the device is unsterile.

Once sterile, the items are transferred to the sterile storage areas before being distributed to where they are needed. Throughout this period, they will remain sterile, unless an event renders them unsterile.

Safety first

Providing a clean, disinfected room and sterile equipment is essential for ensuring that medical and surgical instruments do not transmit infectious pathogens to patients during emergency and routine operations. Failure to ensure a spotless environment or suitable storage condition could lead to an outbreak of infection. When carried out properly, disinfection and sterilisation of invasive and non-invasive medical devices will ensure their safe use, with the method of cleaning dependent on the device itself.

When considering best practice in sterilisation storage, it is necessary to consider the process as a whole – from initial disinfection to placing the item on a shelf – since each step is important for ensuring that medical and surgical devices are stored effectively and reliably, preventing contamination. The method of sterilisation and means of packaging is dependent on the instrument itself, and the packaging’s integrity is reliant on its storage conditions. The way in which an instrument is stored will have a direct impact on its sterility, so it is a matter of the utmost priority to consider this in order to ensure patient and workforce safety.