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(Advanced Sterilisation Products) claim that flexible endoscopes may be

processed using this particular system but special adapters (H2O2 boosters) are

required for use with lumened devices to ensure the disinfectant or sterilant gains

access to thes areas. Very long narrow lumens, and those closed at one end, are

unsuitable for sterilisation using gas plasma. The endoscope must be thoroughly

clean and dry before sterilisation and process - compatible packaging materials

must be used. The entire cycle takes only 75 minutes but, as with ethylene oxide,

biological indicators are required for routine monitoring and these require lengthy

incubation periods. Although no toxic emissions result from the process, these

technical problems, especially the long cycle time, make gas plasma impractical

for routine processing of most gastrointestinal instruments.

Automated endoscope washer/disinfectors

These have become an essential part of most endoscopy units as they increase

instrument through-put and reduce staff contact with disinfectant (41). The

machine must be effective, safe, reliable and able to cope with endoscope design

and through-put. Several endoscope washer/disinfectors of different design are

available. They do not negate the need for manual cleaning of the insertion tube,

suction/biopsy channel, instrument tip and valve recesses, but do offer several


a. They ensure complete irrigation of all channels i.e. biopsy, suction, air,

water, auxiliary water, CO2, although the bridge raiser channel on

duodenoscopes cannot be irrigated by most currently marketed machines.

b. They offer a more reliable and reproducible decontamination procedure

than manual processing and are more convenient for endoscopy staff.

c. They reduce the likelihood of eye, skin and often respiratory exposure to

the disinfectant.

Endoscope washer/disinfectors also have some disadvantages:

a. Regular maintenance is required to ensure tanks, pipework, strainers,

filters and other machine components are free from deposits, biofilm and


b. Processed endoscopes may become recontaminated during the rinsing

stage of the cycle either from the machine of the water supply. The

Department of Health recommends pre- pre-sessional disinfection of the

machine which should include all fluid pathways (4,42). Pseudomonas

aeruginosa, other Gram-negative bacteria and atypical mycobacteria have

been isolated from machines and rinse water. These have led, on

occasions, to machine infection and 'pseudoinfection'. Some machine

isolates of Mycobacterium chelonae are extremely resistant to

glutaraldehyde, and an alternative disinfectant, i.e. a chlorine releasing

agent or peracetic acid, should be used for machine disinfection (42,43).

The water used for the final rinse should be of a suitable quality for the

endoscopes being processed and therefore a water treatment system may

be required. Water softeners, membrane cartridge filtration down to 0.2u,

ultraviolet light and heat treatment have all been used to prevent

contamination with limescale biofilm and microorganisms.

c. Manual cleaning of the endoscope remains an essential pre requisite to

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