VOL: 96, ISSUE: 38, PAGE NO: 5
Carole Crowson, RGN, DipN, is endoscopy manager, Peterborough District Hospital
Flexible endoscopy is a common clinical procedure and all patients undergoing it must be protected from infection, which can occur by one of three routes: from patient to patient, from environment to patient or from organisms within the patient’s body (Donald, 1997).
Various reports have documented transmission in this way (Chmel and Armstrong, 1976; Debongnie and Bouckaert, 1993; O’Connor et al, 1982; Nelson et al, 1983; Birnie et al, 1983; Spach et al, 1993; Medical Devices Agency, 1996). It is therefore essential that endoscopes are cleaned thoroughly and correctly disinfected after each use and that the guidelines for cleaning and disinfecting flexible endoscopes are adhered to strictly.
Over the years the British Society of Gastroenterology has set up several working parties to address these issues. The society’s first paper, published in 1988 as practice guidelines, is still used for the cleaning and disinfection of endoscopes (British Society of Gastroenterology, 1988).
It is vital to clean endoscopes manually as this can remove 95% of the organic debris and micro-organisms that may be present.
Any organic debris left on the endoscope, such as blood or mucus, can prevent adequate penetration of the disinfectant or sterilising medium and glutaraldehyde, which is the most widely used disinfectant (British Society of Gastroenterology, 1998), acts as a fixative on these materials.
Failing to clean endoscopes correctly can also result in the instrument channels becoming blocked, leading to inadequate functioning. To understand how to clean flexible endoscopes, nurses need to know how these instruments are constructed and work (Hawkes, 1997).
The cleaning process
Instruments should be checked for any faults before they are used. If the instrument has been properly cleaned and disinfected at the end of the previous day there is no need to clean it again, but it must be put through the disinfecting cycle (British Society of Gastroenterology, 1998).
The cleaning and disinfection of endoscopes should be carried out in a room dedicated for this purpose.
Before the instrument is removed from the light source/video processor, the air/water channel should be flushed for at least 15 seconds to expel any blood, mucus or other debris. Some manufacturers provide a special valve for this purpose.
Clean water should be sucked through the suction channel and the instrument should be removed from the electrical equipment and washed in warm soapy water. It must be fully immersed in the water to ensure adequate cleaning.
The outer surface of the endoscope should be cleaned thoroughly, paying particular attention to the control section, the angulation controls, the distal end (especially the air/water nozzle) and the bridge mechanism of duodenoscopes. All valves should be removed and cleaned separately with a soft brush.
The suction/biopsy channel should then be cleaned with a flexible brush of the correct size. The brush should be passed through the suction port in two directions: the insertion tube and umbilicus. Then it should be passed down the biopsy channel.
When the brush appears at the end of the endoscope it should be cleaned with a toothbrush before it is drawn back through the instrument. This procedure should be repeated until the cleaning brush is completely clean when it emerges (at least three times down each channel).
Some endoscopes have special characteristics, in which case the manufacturer’s advice should be followed.
When the channels have been cleaned, the suction, air/water and biopsy ports should be cleaned with a soft brush.
The brushes used should then be cleaned thoroughly by putting them through an ultrasonic cleaner or equivalent before they are packed and sterilised. If this is not possible they should be disinfected with the endoscope.
After thorough cleaning, the endoscope is ready to be disinfected.
Flexible endoscopes should be disinfected in automatic washing or disinfection units. Trays, bowls and buckets are not acceptable (Cowan, 1993).
Glutaraldehyde is still the most commonly used disinfectant, but it is an irritant and sensitiser. The vapour can cause rhinitis, conjunctivitis and asthma, while the liquid can cause dermatitis. Other non-specific symptoms of exposure to glutaraldehyde include headache, nausea and vomiting (Medical Devices Agency, 1996). It is therefore essential that exposure is kept to a minimum.
Substantial reductions in atmospheric levels of glutaraldehyde are required under The Control of Substances Hazardous to Health Regulations (Health and Safety Executive, 1988), which were revised in 1994.
The COSHH regulations also stipulate that there should be adequate ventilation and that exhaust systems must be in place to remove any fumes, and Bulletin 9607 (Medical Devices Agency, 1996) advises users to adhere to disinfectant manufacturers’ contact/immersion times.
These recommendations prompted the British Society of Gastroenterology to look at its guidelines on cleaning and disinfection (1988). It concluded that most of its recommendations had stood the test of time but that most countries and manufacturers now recommend immersion in 2% glutaraldehyde for 10 minutes or longer for routine endoscopy.
In response, a British Society of Gastroenterology working party decided to address two issues related to disinfection: disinfectant and immersion time. The working party considered various alternatives to glutaraldehyde, all of which had to be at least as microbicidal, non-irritating and compatible with endoscope components and decontamination equipment.
Many of these products are still undergoing field trials but could be used as alternatives to glutaraldehyde in future.
The working party’s conclusions were similar to those of Babb and Bradley (1995), who reviewed various alternatives to glutaraldehyde but concluded that it was too early to recommend a replacement.
If a replacement was proposed, they advised that the manufacturers of both the instruments and the processing equipment be contacted to validate their guarantees. The requirements of the regulations governing hazardous substances also needed to be established (Health and Safety Executive, 1988), they said.
The British Society of Gastroenterology currently recommends that glutaraldehyde remains the disinfectant of choice but that disinfecting contact times (see box) are brought into line with other countries (1998).
When the disinfection cycle has been completed, the endoscope should be rinsed thoroughly both internally and externally using fresh, sterile or filtered water according to policy. It should then be drained and flushed with air, which can be done manually or in an automated system.
Finally, 70% isopropyl alcohol should be flushed through the endoscope to dry the interior - again, this can be done manually or as part of the automated cycle - before it is reassembled for use.
To prevent the risk of infection, single-use or autoclavable accessories should be used wherever possible. Reusing accessories labelled for single use will transfer legal liability for the safe performance of the product from the manufacturer to the user or employer (Medical Devices Agency, 1995).
Glutaraldehyde remains the main disinfectant for use on flexible gastrointestinal endoscopes, so it is important that staff are fully aware of the COSHH recommendations and the protection they need when using it. They should also have a regular health screening programme and should be aware of any new disinfectants and recommendations.
Semi-disposable endoscopes have been developed but are not in general use and autoclavable endoscopes could be manufactured in future. One company recently developed an endoscope that allows manual brushing of the air/water channel, which should improve the decontamination process and make air/water channel blockages a thing of the past.