Medical Devices Decontamination - Assignment Example

Medical devices decontamination - Compare and contrast the quality of water required for steam generation and for the final rinse stage of an endoscope washer-disinfector INTRODUCTION: Disinfection is a process essential for ensuring an effective removal of infecting organisms from medical devices such as endoscopes and dental apparatus etc which need to be re used again and again. Disinfection is generally carried out by steam generation in autoclaves or by the use of an endoscope washer disinfector. For both of these equipments, water is required. The autoclave requires water for steam generation and the endoscope washer-disinfectors require water during the final rinse stage after being treated with all the chemicals. The purpose is to remove the residues of the chemicals used which, if left untreated at this stage, can lead to damage to the equipment. Autoclaves require the steam generation at high temperatures in order to carry out an effective disinfection. These higher temperatures are targeted to kill the micro organisms sensitive to heat. The endoscope washer disinfectors usually consist of a series of steps in which disinfection is primarily carried out by different bactericidal chemicals and the final step is to rinse the equipment in clean water in order to get rid of the remnants of these chemicals as well which if not removed properly, can lead to a damage to the endoscope thereby limiting its efficiency. If the quality of water used in these equipments is not maintained, it can lead to an outbreak of infections resulting from the micro organisms present in ordinary water. Simple tap water cannot be used for this purpose as it can contaminate the endoscope with micro organisms, chemicals, particulates and endotoxins; thus transmitting infection to the patients. Thus only the sterile water is used for disinfecting endoscopes. Now there are certain criteria and standards set for the quality or water to be used either for the steam generation in autoclaves, or for the final rinse stage of disinfection of endoscopes. QUALITY OF WATER FOR STEAM GENERATION: The water used for steam generation in autoclaves can also adversely affect the performance and life time efficacy of the autoclave. The water used in autoclaves must be free of ions, metals, particles, bacteria and chlorides. The water used for steam generation in autoclaves has been set various standards by both the European standard EN 285:2006 and the United States standard ANSI/AAMI ST79:2006. The maximum water impurity levels suggested by them, as shown in the table created by Millipore are given below: Parameters AAMI ST79 EN 285 Evaporation residue ≤ 15 mg/L ≤ 10 mg/L Silica ≤ 2 mg/L ≤ 1 mg/L Iron ≤ 0.2 mg/L ≤ 0.2 mg/L Cadmium ≤ 0.005 mg/L ≤ 0.005 mg/L Lead ≤ 0.05 mg/L ≤ 0.05 mg/L Other heavy metals ≤ 0.1 mg/L ≤ 0.1 mg/L Chloride ≤ 3 mg/L ≤ 2 mg/L Phosphate ≤ 0.5 mg/L ≤ 0.5 mg/L Conductivity (at 25°C) ≤ 50 µS/cm ≤ 5 µS/cm pH 6.5 to 8 5 to 7.5 Appearance Clean, colorless, no sediment Clean, colorless, no sediment Hardness ≤ 0.1 mmol/L ≤ 0.02 mmol/L NOTE : The values reported in this table are for information only. It is the responsibility of the user to verify the values that apply in his/her specific case. Water for Autoclaves (Millipore n. d.) QUALITY OF WATER FOR ENDOSCOPE WASHER-DISINFECTORS: In 1995, the Health Technical Memorandum (HTM) 2030 was produced by the NHS Estates. It provided certain standards for the use of washer-disinfectors. It stated that: “the final rinse water used for invasive endoscopes should be sterile, and for non-invasive endoscopes ‘it is preferable that it is sterile’.” In an endoscopic washer-disinfector, water is required during three stages: 1. Preparation of detergent, 2. Preparation of disinfectant and 3. Final rinsing. In order to ensure a sterile water system, there are following four methods recommended: 1. It should be filtered using pores as small as 0.1-0.22 micro meter, 2. Reverse osmosis, 3. Addition of biocides, 4. Ultraviolet light and 5. Combining different methods. According to the Health Technical Memorandum: “the final rinse stage should contain 1000 mV and a pH lower than 2.7. (Theme ejournals 1999) SUPEROXIDIZED WATER: While considering the final rinse stage, there is another type of water now introduced, known as the superoxidized water. It is basically composed of hypocholorous acid and at an approximately 144mg/L and the free chlorine radicals. The saline solution is passed over the titanium coated electrodes at 9 amp. The resultant product has a pH of about 5-6.5 with an oxidation reduction potential of >950 mV. (Medscape 2010) Thus, the important fact for the use of water in disinfecting purposes lies in the quality of water which cannot be compromised as the ordinary water itself contains many infective organisms. Using sterile water is a standard set for both the autoclaves and the endoscope washer-disinfectors in order to ensure a high quality disinfected equipment available for use by the physician. REFERENCES Water for Autoclaves (n. d.) Millipore [online] available from: http://www.millipore.com/lab_water/clw4/autoclaves Christina Bradley (n. d.) Water Quality in Endoscope Reprocessing. Hospital Infection Research Laboratory. City Hospital Birmingham, U.K. Decontamination and Disinfection Fact Sheet (2005) United Lincolnshire Hospitals, NHS Trust S. Tsuji et al (1999) Endoscope Disinfection Using Acidic Electrolyte Water. Theme ejournals [online] 31(7): 528-535. Available from: https://www.thieme-connect.com/ejournals/abstract/endoscopy/doi/10.1055/s-1999-55 Dr. Rutala and Dr. Weber (2001) New Disinfection and Sterilization Method: A New Disinfectant: Superoxidized Water. Medscape Today [online]. Available from: http://www.medscape.com/viewarticle/414420_5 Read More