Presenter: Malcolm McLaughlin Date: 04/04/2019 A Review of Medical Device and Optical Critical Cleaning
Introduction Malcolm McLaughlin VP, Product & Business Development 30+ years detergent formulation, cleaning process development, cleaning validation, and analytical residue detection experience 2
Define Critical Cleaning Critical Cleaning What is critical cleaning? Cleaning that impacts the value of the finished output from whatever is being cleaned Typically some observation, measurement or validation is done related to precision cleaning Critical cleaning in FDA or USDA regulated industries of components or substrates is the complete removal of undesirable contaminants to a desired preset level. The preset level is normally the minimum level at which no adverse effects take place in a subsequent operation. 3
Medical Device and Optic Cleaning = Critical Cleaning Numerous examples within the medical device and optic industries of the perils of not focusing on critical cleaning Medical Device Industry Major hip implant manufacturer Optic Industry Optical Malfunction 4
Medical Device Example Why Precision Cleaning and Cleaning Validation is Important Infamous Example Cleaning failures can be very costly One company tried to bring a cleaning/passivation process in house and save less than $2.00/device However the cleaning/passivation processes were not properly validated and due to the thought that well, we don t need to do that cleaning validation and waste time there was tragedy 5
Medical Device Example Why Precision Cleaning and Cleaning Validation is Important Infamous Example What happened???? The company had to recall nearly 25,000 hip implants, 17,500 of which had already been implanted in patients, needing explants This catastrophic series of events lead to the destruction of this large medical device company as a stand alone company. 6
Optics Example A well established German optic company Residues on the surface causing diffraction of light Couldn t have any damaging ingredients Couldn t have any rinse aids or corrosion inhibitors Used Liquinox to clean lenses are eliminate light diffraction and accurate transmission problems 7
Critical Cleaning: Cleaning Process Development and Optimization 4. The 9 Variables of Effective Cleaning It is not only the cleaner that determines cleaning success; remember the 9 variables: BATH-O-CARD 1. Before-clean 6. Chemistry/Conc. 2. Agitation 7. After-clean 3. Time 8. Rinsing 4. Heat 9. Drying 5. Orientation 8
Cleaning Process Development and Optimization 1 Before-Cleaning Handling Clean surfaces as soon as is practical after they are dirty Dried on residues are more difficult to clean than fresh ones Pre-soaking can help remove dried on residues Storing parts in a cleaner environment prior to cleaning makes them easier to clean 9
2 Agitation Use high foaming or sometimes low foam detergents Manual Soak Ultrasonic Use low foaming detergents Automatic Spray Washer Dishwasher Sprayball Clean-In-Place Cleaning Process Development and Optimization 10
Cleaning Process Development and Optimization 3 Time and Cleaning Effectiveness For digesting mechanisms, time vs. cleaning is linear Allow time especially for enzyme methods Soaking requires time: can take hours Cooler solutions take more time (every 10 deg C 11
Cleaning Process Development and Optimization 4 Heat Cleaning speed doubles every 10 C (~20 F) increase Above the melting point of waxes and greases, emulsification rather than just dispersion can occur; over 77 C (170 F) often effective 12
Cleaning Process Development and Optimization 5 Orientation Cleaner can access all surfaces Blind holes Dead legs in piping systems Shadowed surfaces in automated spray cleaning Coverage inside dishwasher Not pooling solution inside a dishwasher Orient for drainage 13
6 Chemistry Low foaming or high foaming depending on agitation Low foam for high agitation, pressure spray High foam and sometimes low foam for manual, soak and ultrasonic Alkaline high ph, neutral ph, or acidic low ph Residue type Worker safety Substrate compatibility Cleaning Process Development and Optimization Chelation capacity to compensate for hard water 14
Cleaning Process Development and Optimization 6.1 Chemistry and Soil Type Natural Oils - higher alkaline cleaners Synthetic and Petrochemical Oils - wetting, emulsifying; typically mild alkaline Salts, Oxides, Metals - alkaline chelating, sequestering cleaners, best with acid cleaners Particulates - dispersant cleaners Protein/biofouling - protease enzyme cleaners; mild alkaline with wetting agents 15
Cleaning Process Development and Optimization 6.2 Chemistry ph and Cleaning Type Cleaner ph Typical Soils Mineral acid 0-2 heavy scales Mild acid 2-5.5 salts, oxides, metallic Neutral 5.5-8.5 light oil and particle Mild alkaline 8.5-11 oils, particles, films Alkaline 11-12.5 natural oil, fat, resin Corrosive 12.5+ heavy grease/soils 16
6.3 Chemistry and Substrate Type Aluminum/soft metal - mild alkaline to modest acid (ph 2.5-9.5); silicated alkaline Mild Steel - corrosion controlled rinse/dry Most Plastics/resins - ok w/ broad range of aqueous cleaners; check solvent content Stainless steel - ok with most alkaline detergents 17
Cleaning Process Development and Optimization 7 After cleaning Handle and store cleaned surfaces in clean areas Store away from humidity or heat if appropriate 18
Cleaning Process Development and Optimization 8 Rinsing and Cleaning Effectiveness Rinse water is the last to touch the surface Evaporation deposits rinse water content Deionized - lower in metals, can be carbon filtered for low organics may need UV/0.2 micron filter Distilled - lower in organics/microbes 19
Cleaning Process Development and Optimization 8 Rinsing and Cleaning Effectiveness (Cont.) Reverse osmosis - best of both; costly Cooler rinse = less corrosion Rinse/wash temp same to avoid break emulsion Rinse hot for easier evaporation drying 20
Cleaning Process Development and Optimization 9 Drying and Cleaning Effectiveness Evaporation deposits rinse contaminants, may promote corrosion Blowing, wiping-off rinse water alleviates problems, but is difficult Particle sensitive drying may require filtered air drying Humidity on cleaned surfaces can cause corrosion 21
Cleaning Process Development and Optimization Process Conclusion Selecting the right cleaner is easier if you understand the 9 variables that effect cleaning performance Match your cleaner to the cleaning method, substrate, and type of residue 22
Medical Device Case Study Problem: calcium salt residues from metalworking fluid were not being cleaned by alkaline cleaning process Solution: Use an appropriate acidic cleaner such as Citranox detergent under typical medical device cleaning conditions: Agitation: 40 KHz ultrasonic tank Time: 20 minutes clean, 2x10 minute Heat: 140-150 deg F (60-65 deg C) Orientation: rack mounted to keep devices separated to avoid trapping residues and dirty wash solution Chemistry: 2% Citranox (2.5 oz/gal or 20 ml/l) Rinse: 140-150 deg F (60-65 deg C) counter flow cascade rinse with 5% rinse volume exchange in 10 minutes using deionized water Dry: Blow off with dry filtered nitrogen 23
Optics Case Study Problem: Precision optics being inappropriately etched by alkaline cleaner being used to remove waxes and resins Solution: Use a milder ph Liquinox detergent under typical precision optical cleaning conditions: Agitation: 130 KHz ultrasonic tank Time: 20 minutes clean, 2x10 minute Heat: 110-120 deg F (45-50 deg C) Orientation: rack mounted to keep devices separated and allows free draining Chemistry: 1% Liquinox (1.25 oz/gal or 10 ml/l) Rinse: 110-120 deg F (45-50 deg C) counter flow cascade rinse with 5% rinse volume exchange in 10 minutes using deionized water Dry: Filtered air oven dryer 24
Throughput and Time Optimization Applying BATH-O-CARD concepts: 10 deg C increase doubles cleaning speed Increase chemistry concentration for bath life Optimize substrate orientation for cleaning and rinsing speed Increase agitation to increase cleaning speed Use the correct chemistry for faster cleaning Low foaming cleaners can rinse faster 25
Conclusion The successful manufacturing and functioning of both medical devices as well as optics rely on effective cleaning Understanding the basics of cleaning and detergents will lead to proper detergent selection Understanding the process factors in the design of a cleaning process may influence the success of your product and avoid disaster 26