EVALUATION REPORT
PLADE 2000 AUTO-DISINFECTOR (TWIN SCOPE) PLADE LTD
MARCH 1994 UNIT NAME Auto-Disinfector Model 2000 SUPPLIER/MANUFACTURER Plade Ltd
Plade Works
Gladstone Avenue
Barrhead
GLASGOW
Scotland G78 1QT
PRICE (Please email telephone or write for the up to date price.)
INTENDED USE
The cleaning and disinfection of submersible flexible endoscopes. The machine will accept endoscopes from all leading manufacturers. Top
HOW IT FUNCTIONS
Detergent solution, disinfectant and rinse water are circulated throughout the internal lumens of the endoscope and the trays filled with detergent and disinfectant to decontaminate all external surfaces of the endoscope. Detergent solution and rinse water are discarded to waste with each cycle. The machine will accommodate two endoscopes in separate trays which can be processed either synchronously or asynchronously. All functions are controlled by computer software and disinfectant contact times can be individually programmed by the user. Two disinfectant holding tanks, each holding 15 litres, are situated in the base of the machine. The number of disinfectant cycles can be programmed and the machine will draw disinfectant to both trays, from the holding tank containing the disinfectant nearest the end of its use life. An option is available to dedicate one tray and disinfectant tank to a particular instrument(s) if so required.
Scope cleansing and disinfection are performed inside a fume cupboard which extracts irritant and sensitizing aldehyde fumes. These are passed thorough adsorbent charcoal filters before being either recirculated or discharged to the outside. Top
USER INSTRUCTIONS
Plastics Design and Fabrications Ltd produce an indexed manual of installation, operation and maintenance. This is very comprehensive and requires careful study before use of the machine. However, the computer based control system features a menu-driven programme which is easy to use and gives the user on screen help and instruction on decontamination and safety (inc COSHH). The user also has control over all machine variables, eg disinfectant contact times, cycle programme details and number of 'use life' disinfectant cycles, etc. However, a password (chosen by a designated user) is required to alter these variables. Top
TECHNICAL DATA
- Dimensions:
- Width 1125 mm
Height 2350 mm
Depth 975 mm
Electrical requirements: 240 v single phase
Water supply: Cold mains water, supply pressure advised 1.25 bar
Drain requirements: Gravity drain, floor level
Recommended detergent/disinfectant:
Low foaming detergent (neutral or enzymatic) compatible with the disinfectant used, eg Hospec Neutral Detergent. The detergent must be diluted to the required strength (unspecified by Plade) before adding to the detergent storage tank. From here, it is automatically further diluted for use and finally discarded to waste. Disinfection is achieved using 2% glutaraldehyde from one of two 15 litre storage tanks. The type of disinfectant, concentration and contact times selected for this evaluation were in accordance with national guidelines (BSG). The post activation use life in respect of the number of disinfection cycles (but not days post activation) can be preset. When this period has elapsed the machine informs the user of the situation and either uses disinfectant from the other holding tank or, if this is not possible, ceases to operate.
Pumps: There are 3 transfer pumps situated underneath the trays, one each for water, disinfectant and waste. These are of the 'vane positive displacement' type and have a capacity of 25 litres/min. There are a further two 'recirculation' pumps to circulate the fluid in each of the two trays. These are diaphragm type, and have a capacity of 0.75 litres/min.
Filters: Drain filters (strainers) are situated below the trays, and on the suction side of the scope irrigation pumps. These require regular cleaning. An air pre filter is situated in front of the carbon filters. The pre filter comprises of polyurethane foam with an estimated efficiency of 90% at 5-7 µm. It is recommended that this is periodically removed, checked and cleaned if necessary. The adsorption filter is activated carbon, with an estimated efficiency of 90%. The design of the containment cabinet is in accordance with the recommendations of British Standard 7258 (1990). If used in the recirculating mode it is, however, outside the scope of the British Standard. Top
SERVICE/SHARED PLANNED PREVENTATIVE MAINTENANCE ARRANGEMENTS
Recommendations are given by Plade for routine maintenance procedures which can be performed by the users, eg cleaning drain strainers, checking and cleaning pre filters, etc. It is also recommended, for example, that every six weeks the circulating pump filter is removed and rinsed. Some of these checks may not easily be carried out by endoscopy staff. It is stated in the instruction book that failure to carry out regular routine cleaning and janitorial procedures may lead to a loss of warranty and/or service contract cover. This requires clarification. The manufacturers period of warranty is 12 months against defective or faulty workmanship. Travelling time and cost for on site warranty claims will however, be charged. Top
CONSTRUCTION AND INSTRUMENTATION
This is a large floor standing machine constructed largely from 12 mm white polypropylene. Activated disinfectant is stored in two sealed tanks within the main unit. On commencement of a cycle detergent is diluted with mains water fed into the top tray via a water holding/feeding tank. After use the detergent is discarded to waste. The user then has the option to rinse before the disinfectant is pumped rapidly into the processing tray. This is returned to the holding tank from which it came and the endoscope rinsed in water drawn from the feeding tank. The user can select the number of rinses after disinfection before the water is discarded to waste.
Two quick release connection ports are fitted on the side of each scope processing tray. Adapters are connected to these to irrigate all channels of the fibrescope. No indication is given in the manufacturers instructions as to how to connect various endoscopes.
Two endoscopes may be processed synchronously or asynchronously in the contoured scope processing trays. Each tray is fitted with a combined drain and disinfectant fill and a separate fresh water supply spout with an integral detergent dose nozzle. The machine is plumbed into the low pressure water supply (in accordance with local water authority requirements) and located near a drain. There is no integral filtration system to remove micro-organisms or particulate matter from the mains water, but this is available as an option if required. The disinfectant contact time can be programmed into the software by the user.
The cleansing time and length of the two rinses can similarly be programmed by the user, as can the use life of the disinfectant. This is done by accessing the routine maintenance menu. In order to do this, it is necessary to enter a 4 digit password.
All functions of the Auto-Disinfector are actuated through a touch sensitive 17 key keypad. A cursor controlled highlight bar on the VDU can be used to select and activate a selected option. An automatic function control applies when the unit is switched on and after this the main menu is displayed. The program and status of each tray is separately indicated.
An extraction system, controlled by a standard centrifugal fan draws glutaraldehyde fumes from the cabinet, through a filter system comprising of a charcoal absorption unit with pre filter. A fume extraction running time meter is fitted. Tests carried out by the filter manufacturer on filters taken from cabinets in use, suggest that a life of 6000 hr can be expected.
After completion of each cycle, the Auto-Disinfector prints a typed data sheet showing process times, scope reference number and holding tank number, etc. The time remaining for the cycle is counted down, and shown on the VDU. Water from the mains supply is passed first into a feeding tank situated in the side of the cabinet below the processing trays before it is used for detergent and rinse water.
During a cycle, each tray is filled with 5 litres of glutaraldehyde from the holding tank in use. Top
CYCLE TIMES
All times may be selected and programmed by the user. The following cycle times and stages were evaluated.
Fill Circulate Empty
Detergent clean of scope 15 sec 20 sec 20 sec
Rinse scope 15 20 25
Disinfectant scope 15 240 25
Rinse 1 15 20 25
Rinse 2 15 20 25
Airblow 15
Total cycle time 8 min 50 sec (with 4 min glutaraldehyde contact time) Top
TECHNICAL EVALUATION
The Dudley Road Hospital Electro Biomedical Engineering Department have checked the electrical safety of the Plade Auto-Disinfector 2000 and have found that it meets their requirements. However, more rigorous testing would be required to prove total compliance with the ESCHLE and other relevant standards. This is outside the scope of this evaluation. A statement of compliance with relevant standards will be required.
No technical evaluation of the efficiency of the fume extraction system (ie for compliance with BS7258) was performed during this study. Consult the manufacturers for a copy of the test report prepared by Measured Protection Ltd. Top
RELIABILITY
The Plade Auto-Disinfector has not been in use long enough to give an opinion on reliability. Purchasers are advised to seek assurance from those with a continuing experience with the Plade Auto-Disinfector 2000. Manufacturers are advised to supply a list of users that are able to help with such an enquiry. Top
PERFORMANCE
The detergent reservoir was filled with Hospec Neutral Detergent diluted 1/10, (Youngs Detergent, Livingston, West Lothian) and the disinfectant reservoir with 15 litres of activated alkaline glutaraldehyde at a nominal 2% (Asep, Galen Ltd, Craigavon, Northern Ireland). The disinfectant contact time chosen for this study was 4 min. This is the current, between patient, disinfectant contact time recommended by the British Society of Gastroenterology (Gut 1988 29 : 1134-1151) for GI endoscopes. Top
CLEANING EFFICACY
Tests were performed using artificial contamination. An overnight broth culture of Pseudomonas aeruginosa NCTC 6749 (UK disinfectant test strain), enriched with 10% horse serum, was painted onto the external surfaces, ie insertion tube, light guide connector, valve housings, etc and was flushed through all 4 channels, (biopsy, suction, air and water) of an Olympus GIF Q10 submersible gastroscope using an all channel irrigation device (Olympus code CW3). The fibrescope was left at room temperature for 10 min before sampling (control) or processing (test). Ten % horse serum was added to the broth to simulate the organic load likely to be encountered when the instrument is used. All channels were sampled individually, before and after disinfection, to establish pre and post processing counts. These were used to determine the effectiveness of the decontamination procedure. Channel washings were suitably diluted and plated onto blood agar using a surface dropping technique. Culture plates were incubated for 18 hr at 37oC and surviving test organisms enumerated. The results of automated cleaning and disinfection were expressed as log10 reductions.
The fibrescope channels were individually sampled using sterile water, tubing, connectors and syringes as follows:
Biopsy Channel
A short piece of tubing was attached to a 10 ml syringe and the biopsy port. Ten ml of sterile water was flushed down the biopsy channel and the sample collected in a sterile bottle at the distal tip.
Suction Channel
Tubing and a 10 ml syringe were attached to the suction port on the light guide connector and water flushed along the suction channel. To do this the biopsy/suction feed button was depressed whilst the water was introduced and the sample was collected in a sterile bottle at the distal tip.
Air Channel
The air channel was irrigated with 10 ml of sterile water from the air inlet port on the light guide connector and water slowly flushed along the air channel. To do this the suction and water ports on the light guide connector were covered with the finger and thumb and the air/water feed button covered but not depressed whilst the water was flushed along the channel. The sample was collected at the distal tip in a sterile bottle.
Water Channel
Tubing and a 10 ml syringe were attached to the water inlet on the light guide connector and 10 ml of sterile water flushed along the channel. To do this the water feed button was depressed and the sample collected at the distal tip.
The outside of the fibrescope was sampled using swabs and the samples plated onto blood agar. Top
RESULTS
No test bacteria were recovered from external surfaces of the fibrescope and surfaces were visibly clean. Although, on occasions, surviving test organisms were recovered, we would consider a machine that achieves a mean 6 log10 reduction with 2% glutaraldehyde, with no individual channel reductions of << 5 log10, using a disinfectant contact time of 4 min, to be acceptable. Top
GLUTARALDEHYDE ASSAYS
An assessment was made of the dilution of the glutaraldehyde due to carry over of detergent and rinse water during cycles. Assays were performed by Dr A Barnes - Quality Control Department, Pharmacy, Dudley Road Hospital.
The technique used for aldehyde determination (Johnson & Johnson Medical Ltd) in this study was as follows:
A 5 ml sample was added to a stirred 50 ml volume of water in a beaker and the pH adjusted to 3.00 with 0.1 M hydrochloric acid. To this was added 15 ml of aqueous hydroxylamine hydrochloride: 10% w/v, at a pH previously adjusted to 3.00 with either 0.1 M hydrochloric acid or 0.1 M sodium hydroxide. After the pH had stabilised, the mixture was titrated with 0.1 M sodium hydroxide back to a pH of 3.00. Each ml of 0.1 M sodium hydroxide was equivalent to 0.005005 g glutaraldehyde.
It is recommended (Babb, Bradley & Barnes 1992) that glutaraldehyde should not be used if the concentration falls below 1.5%. Twenty five cycles may be performed using the same 15 litres of glutaraldehyde as long as it is within its post activation life of 14 or 28 days. Top
ASSESSMENT OF MACHINE DISINFECTION
The machine self disinfection option is intended for use every night after completion of the days tests. Disinfectant is pumped into the water break tank, and stored until the machine is ready for reuse (usually overnight). Transferring the disinfectant takes 9 min 20 sec after which the machine may be switched off and the process reversed the next morning. This is intended to ensure that all internal surfaces and associated pipework are in contact with the disinfectant for a pre selected time. Unfortunately the detergent dosing system is not included in the automated self disinfectant programme. This problem will have to be addressed by the manufacturers.
One litre of an overnight broth suspension of Ps aeruginosa NCTC 6749 was placed in the water holding tank. The machine was programmed to 'rinse only' to contaminate all internal rinse circuits. A sample was collected for culture to determine the pre disinfection challenge. A machine disinfection cycle was then performed, followed by a further 'rinse only' cycle. A sample of this water was collected and cultured to detect any surviving test organisms. The effectiveness of the self disinfect cycle was established.
In addition, the top tray and connectors were contaminated with Ps aeruginosa and allowed to dry for 10 min. Swabs were taken before and after processing to assess the effectiveness of machine disinfection. Top
RESULTS
After the machine disinfection, no surviving test bacteria were detected from the top tray or connectors. Top
OBSERVATIONS
1 Although the machine is tall, it does not take up any more floor space than would a shorter machine of equivalent width and depth. Care should be taken that it can be manipulated into the space provided.
2 The extremely vigorous and powerful flow of fluid through the channels of the scope ensures effective cleaning and disinfection. It is the responsibility of the purchaser to ensure that the pressures achieved within the scope channels do not exceed the endoscope manufacturers maximum tolerances.
3 When the machine is started up initially, a very bright light flashes 10 times in accordance with BS 7258. This could cause alarm to patients in an endoscopy unit. Users may specify a machine without a beacon if so required.
4 No instructions were given in the manual on how to replace the paper roll for the print out after it has run out. This occurs after approximately 100 cycles. This omission has now been rectified.
5 It was noticed that black particles, thought to be charcoal, were settling on horizontal surfaces of the inside of the machine after several cycles. These may have come from the filter whilst setting up.
6 On one occasion a leak was detected from the water feeder tank. This was thought to be due to particulate matter from the water supply coating the fluid level sensor causing the tank to overfill. The use of filters on the incoming water supply would eliminate this problem (see disadvantages number 1)
7 The glutaraldehyde may be activated either within its 5 litre container or within the machine. Activation within the machine reduces operator exposure to glutaraldehyde.
8 The dilution of glutaraldehyde due to carry over of detergent and rinse water is similar to other machines with the same capacity. It is recommended that the 15 litres in each tank are replaced after processing 25 endoscopes. Top
ADVANTAGES
1 The machine will accommodate submersible endoscopes from all leading manufacturers.
2 The programmes are microprocessor controlled. Clear instructions for the running and maintenance of the machine are given.
3 The machine will accommodate two fibrescopes which can be processed synchronously or asynchronously. This will speed up processing if two or more scopes are used for a busy session.
4 The cycle time is relatively short due to the rapid fill and drain.
5 The machine is constructed of easily cleanable polypropylene.
6 The machine is relatively silent when running.
7 A integral cupboard on the side of the machine allows the user to hang store up to 4 fibrescopes.
8 On screen help and instructions are available, as well as information storage and retrieval.
9 A data bank with information relevant to installation, operation and maintenance of the Auto-Disinfector is provided with information on the chemicals, items to be sterilised, and emergency COSHH procedures. All information can be viewed on the visual display screen.
10 Level indicators show the presence of fluid in the two disinfectant tanks.
11 The working area is well lit.
12 The lid, which can be slid over the unused processing tray, provides a useful additional work surface. Top
DISADVANTAGES
1 The machine is supplied without integral filtration to remove particles and bacteria from the mains water supply before it enters the machine. Filtered water is recommended for rinsing surgical endoscopes and bronchoscopes. 'Optional' filters are advised.
2 No audible signal is given to indicate the completion of a cycle. There is, however, a visual time remaining count down for each tray on the display screen.
3 The fibrescopes are awkward to load into the machine, since it is difficult to access the back of the tray in order to coil the scope. Similar difficulties were encountered with access for cleaning the rear of the machine. The sash lock can be released to fully open the visor for cleaning but this is not advised for loading as it increases the risk of aldehyde exposure.
4 The detergent tank is located to the right, and well back, in the machine. It is therefore, difficult to check and refill.
5 There is no machine self disinfection of the detergent storage tank and dosing system and although some detergents do contain biocides and/or bacteriostatic agents, these become ineffective if the detergent is diluted or stored for long periods.
6 The water holding tank is impossible to access to monitor the performance of the machine self disinfection cycle. Recontamination of the fibrescope is most likely during the post disinfection rinse.
7 An excessive amount of foam was produced. This may affect the performance of the disinfectant by reducing surface contact. It may also affect the sensing of disinfectant levels in the storage tanks. The manufacturers recommend the use of low foaming agents. Top
CONCLUSION/SUMMARY
The Plade Auto-Disinfector 2000 effectively cleans, disinfects and rinses all external surfaces and channels of 2 submersible flexible fibreoptic endoscopes. These may be processed synchronously or asynchronously. At least a 7.49 log10 reduction was achieved in all 4 channels of an Olympus GIF Q10 gastroscope using a serum broth suspension of Ps. aeruginosa. Performance in this respect was favourable and similar to other acceptable automated systems. HIRL performance/acceptance criteria require at least a 6 log10 reduction in all channels.
Disinfection occurs within a fume cupboard which contains and extracts irritant aldehyde vapour which is absorbed and retained within an activated charcoal filter before the air is recirculated or discharged to the outside.
The machine is relatively expensive and complex. However, it will process 2 fibrescopes and is microprocessor controlled. It can be programmed with the disinfectant contact times currently recommended by the manufacturers and displays instructions for maintenance and the safe cleaning and disinfection of endoscopes on a VDU.
The machine has an effective machine disinfect cycle but this does not include the detergent storage tank or dosing system. Also, access to the rinse water feed tank is difficult for monitoring the performance of the self disinfection cycle. Neat detergent requires some dilution before it is added to the storage tank for further dilution. This and prolonged storage will reduce the activity of any bactericidal or static effect and contamination is therefore likely. Manual disinfection is possible but access difficult.
Cleaning was very effective presumably because of the high flow rate in the endoscope channels. Care must, however, be exercised to ensure that pressures do not exceed the maximum, non-damaging, tolerances imposed by the manufacturers.
No integral filter is supplied to remove bacteria from the rinse water (< 0.45u). Sterile or bacteria free water is advised for all endoscopes but is essential for bronchoscopes and surgical endoscopes.
As with all machines, the potency of glutaraldehyde is reduced due to carryover of rinse water and detergent. We recommend that the 15 litres of glutaraldehyde in each tank is replaced after processing 25 fibrescopes.
The manufacturers have advised this laboratory that, since our evaluation and report (February 1994) several modifications have now been made to subsequent production units which is believed will improve performance and user friendliness. These are listed as manufacturers comments in Appendix 1 attached to this report. It is most unlikely that these modifications will effect the favourable performance of this machine in respect of its ability to clean and disinfect submersible flexible endoscopes.
LR Simpson - MTO
CR Bradley - Senior MLSO
JR Babb - Laboratory Manager Top
REFERENCES
Babb JR, Bradley CR & Barnes AR (1992) Question and answer : dilution of glutaraldehyde Journal of Hospital Infection 20 : 51-54
Babb JR (1993) Disinfection and sterilization of endoscopes Current Opinion in Infectious Diseases 6 : 532-537 Top
MANUFACTURERS COMMENTS
The following modifications have been made to the Plade 2000 Auto-Disinfector.
1 An optional 4 stage water filtration system is available with a 0.2 µ absolute final filter.
2 Disinfection of the detergent tank and dosing system is now part of the automated machine disinfectant programme.
3 The detergent tank has been repositioned and the size of the fill port increased. This enables easier access for filling.
4 The user now has access to the water tank and can monitor the performance of the machine disinfect cycle.
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