The purpose of medical device cleaning validation is to assure that the medical device cleaning procedure are consistently controls potential carryover, contaminants, cleaning agents and extraneous material into the device to a predetermined level which will not pose a risk to the patient and will meet cleaning validation acceptance criteria.
Based in regulatory requirements, equipment and medical devices shpuld be cleaned and stored in a way that will prevent contamination and cross-contamination that may risk patient health.
There are several aspects that should be taken into consideration before cleaning process is established: the desired cleanness level, cost of the cleaning agents and cleaning process, risk of cleaning process residues, toxicity and cleaning agents safety and compatibility.
This article is focused on several medical devices cleaning techniques and cleaning validation such as manual cleaning and ultrasonic bath.
Preparation towards Medical Devices Cleaning Process
After identifying, analyzing and assessing the risks involved with medical device usage and subsequently the required cleanliness level, a cleaning process should be developed and validated. There are several considerations that should be taken before cleaning process validating:
- The required cleanness level
- Cost of cleaning agents and cleaning process (energy, time, labor and materials)
- Cleaning agents, safety and compatibility
- Risk of cleaning process residues for the patient
Manual cleaning is often being used in cases an automated cleaning process (Clean In Place/ Clean On Place) cannot be implemented and/or may damage the medical device or in cases that small quantities of devices are required to be cleaned (for example medical device that should be cleaned towards clinical trial).
Medical devices manual cleaning method can include a combination of solvents, detergents, soaking, scrubbing, rinsing and washing under pressure and temperature. This type of cleaning involves high labor costs and inconsistency due to lack of measure/quantify cleaning process parameters and control. The manual cleaning method may be used as a first cleaning step of a multiple stage cleaning process. Moreover, manual cleaning method cannot be validated properly/
Medical Device Cleaning using an Ultrasonic Bath
Ultrasonic bath cleaning is commonly used in the medical device industry for products like guide wire, metal parts, assemblies and implants. The ultrasonic cleaning method is usually used after devices have been initially cleaned to remove bulky impurities, particles and greasy materials residuals. This method is designed to remove fine impurities only. The ultrasonic bath may be used with water, detergent or solvents (such as Ethanol) and operated at temperatures that vary from 15˚C to 140˚C. The detergent will be chosen based on the impurity physical and chemical characteristics. For organic impurity alkaline detergent is suitable and for inorganic impurity acid detergent is suitable. The process may be followed by rinse with purified water.
Ultra-sonic cleaning process for medical devices involves ultra-sound waves at 20–130 kHz frequencies create cavitation bubbles that inflect force against contaminations adhering or embedded to the surface of to the medical device parts surface. At higher frequencies, the cavitation bubbles increase in number and decrease in size. Larger bubbles have more energy released when they interact with the material. For smaller parts it is better to employ a large amount of smaller bubbles that are able to penetrate small areas.
Ultrasonic cleaning is suitable for devices with un-even/homogenous surfaces that may "trap" impurities.
Ultrasonic can induce significant damage to small medical devices like stent's, specifically devises with resonant frequency near the one used in the ultrasonic bath.
Using Ultra-sonic bath method should include the following parameters:
- Ultrasonic frequency
- Ultrasonic power
- Cleaning time
- Cleaning agents
- Ultrasonic bath temperatures
- Quantity of parts/medical device per cycle
- Ultra-sonic bath location (clean room classification)
- Drying procedure
Medical Device washer and disinfection machines
This type of multi-stage cleaning process is consisting of several stages that may vary depending on impurities type and the desired cleanness level. Example of a typical medical device cleaning cycle: Highly alkaline pH followed by a rinse to neutralize the pH and continue with high acidic rinse solution and afterwards purified water rinse. Medical device sub-parts may include in addition, soaking, enzymes incubation and ultrasonic treatment. The advantages of medical device cleaning using washer are that it is an automated process, easy to operate, usually with minimal pre-treatment stages and labor.
Using an automatic washer
Should include the following parameters:
- Washing time
- Washing temperature
- Loading patterns
- Water quantity
- Acid and alkaline solutions
- Ultrasonic capabilities
- Critical parameters online monitoring (conductivity)
Image 3: washer disinfector
Medical Device Cleaning Validation
As per regulatory requirements, equipment and medical devices shall be cleaned in order to eliminate contamination and to minimize patient's risk. The purpose of medical device cleaning validation is to assure that the medical device cleaning procedure consistently controls potential carryover, contaminants, cleaning agents residuals and extraneous material into the device to a pre-determined level which will be reflected in the cleaning validation acceptance criteria.
Medical device Cleaning Validation will be performed based on an approved cleaning validation protocols. The cleaning validation wll include worst case such as Medical device cleanness level, shortened cleaning process etc.
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