News / July 2, 2020
In Part I of ‘How to Properly Clean Surgical Instruments’ we discussed how important proper, thorough and complete cleaning is when it comes to protecting patients from surgical infections caused by instruments that remain contaminated after reprocessing. Specifically, surgical instruments must be thoroughly cleaned before high-level disinfection and sterilization because inorganic and organic materials that remain on the surfaces of instruments and medical devices interfere with the effectiveness of these processes. Always remember that even after a thorough and complete sterilization cycle, “If it’s not clean, it can’t be safe!”
Part I of ‘How to Properly Clean Surgical Instruments’ concluded with a description of washer-sterilizers. In Part II we will begin with a description of washer-disinfectors.
Washer-disinfectors are typically computer-controlled units that are designed for cleaning, disinfecting, and drying both solid and hollow surgical devices and equipment. In one published study, cleaning (being generally defined as a log reduction of 5–6 log10 ) was achieved on all of the device surfaces that had adequate contact with the water flow in the machine.1 For more detailed information about cleaning and preparing supplies for terminal sterilization, please consult some of the numerous professional organizations (2,3) and books.4
For instrument cleaning, a neutral or near-neutral pH (7 or lower) detergent solution is commonly used because such solutions generally provide the best material compatibility while providing good soil and debris removal. Enzymes (usually proteases) are sometimes added to neutral pH solutions to assist in removing organic material. Enzymes in these formulations attack proteins that make up a large portion of common soil and debris (e.g., blood, pus).
Cleaning solutions also can contain lipases (enzymes active on fats) and amylases (enzymes active on starches). Enzymatic cleaners are not disinfectants, and proteinaceous enzymes can be inactivated by germicides. As with all chemicals, enzymes must be rinsed from the equipment or adverse reactions (e.g., fever, residual amounts of high-level disinfectants, proteinaceous residue) could result from the contaminated instruments and devices (5, 6).
Enzyme solutions should only be used in accordance with the manufacturer’s published instructions for use (IFUs). These IFUs will list the proper dilution of the enzymatic detergent and specify the length of time the solution should be in contact with the medical device.7 Please be aware that the use of detergent enzymes can, however, result in asthma or other allergic effects occurring with users. Detergent solutions with a neutral pH that contain enzymes are the best choice for cleaning delicate surgical instruments and devices, especially endoscopes, due to the detergent’s compatibility with metals and materials found on delicate medical devices.8
Alkaline based solutions and cleaning agents are frequently used for processing medical devices because they are very effective at dissolving protein and fat residues (9); however, they can be corrosive on delicate instruments and medical devices.10 Always consult the manufacturer’s IFUs before using an alkaline based cleaning solution or agent on your instruments and your delicate medical devices.
When attempting to remove microorganisms and biofilms, published studies have validated the fact that enzymatic cleaners are more effective than neutral detergents (11, 12) in removing microscopic organisms and films from the surfaces of instruments and medical devices. Contrary to some manufacturers’ claims, published studies have found no difference in cleaning efficiency between enzymatic and alkaline-based cleaners (13, 14).
1 Ransjo U, Engstrom L, Hakansson P, et al. A test for cleaning and disinfection processes in a washer-disinfector. APMIS 2001; 109:299-304.
2 American Society for Hospital Central Service Personnel. Training manual for central service technicians. Chicago: American Hospital Association, 2001:1-271.
3 Ninemeier JD. Central service technical manual. Chicago: International Association of Healthcare Central Service Materiel Management, 1998
4 Reichert M, Young JH. Sterilization technology for the health care facility. Gaithersburg: Aspen Publication, 1997:307.
5 Alfa MJ, Nemes R, Olson N, Mulaire A. Manual methods are suboptimal compared with automated methods for cleaning of single-use biopsy forceps. Infect Control Hosp Epidemiol 2006; 27:841-6.
6 Lee CH, Cheng SM, Humar A, et al. Acute febrile reactions with hypotension temporally associated with the introduction of a concentrated bioenzyme preparation in the cleaning and sterilization process of endomyocardial bioptones. Infect. Control Hosp. Epidemiol. 2000; b21:102.
7 Hutchisson B, LeBlanc C. The truth and consequences of enzymatic detergents. Gastroenterol. Nurs. 200
8 Roberts CG. Studies on the bioburden on medical devices and the importance of cleaning. In: Rutala WA, ed. Disinfection, sterilization and antisepsis: principles and practices in healthcare facilities. Washington, DC: Association for Professional in Infection Control and Epidemiology, 2001:63-9.
9 Zuhlsdorf B EM, Floss H, Martiny H,. Cleaning efficacy of nine different cleaners in a washer-disinfector designed for flexible endoscopes. J. Hosp. Infect. 2002; 52:206-11.
10 Roberts CG. Studies on the bioburden on medical devices and the importance of cleaning. In: Rutala WA, ed. Disinfection, sterilization and antisepsis: principles and practices in healthcare facilities. Washington, DC: Association for Professional in Infection Control and Epidemiology, 2001:63-9.
11 Merritt K, Hitchins VM, Brown SA. Safety and cleaning of medical materials and devices. J. Biomed. Mater. Res. 2000; 53:131-6
12 Babb JR, Bradley CR. Endoscope decontamination: where do we go from here? J. Hosp. Infect. 1995; 30:543-51.
13 Loukili NH, Zink E, Grandadam S, Bientz M, Meunier O. Effectiveness of detergent-disinfecting agents on Escherichia coli 54127 biofilm. J. Hosp. Infect. 2004; 57:175-8.
14 Zuhlsdorf B EM, Floss H, Martiny H,. Cleaning efficacy of nine different cleaners in a washer-disinfector designed for flexible endoscopes. J. Hosp. Infect. 2002; 52:206-11
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