To provide more information on reusable device validations, Pacific BioLabs conducted a webinar on reusable devices. The webinar covers an overview of requirements and presents three case studies of validations performed on devices of various complexity.
The webinar can be accessed in a recorded format or as a slide presentation.
- ANSI/AAMI ST58:2005 – Chemical Sterilization and High-Level Disinfection in Health Care Facilities
- AAMI TIR 12:2010 – Designing, Testing and Labeling Medical Devices for Reprocessing in Health Care Facilities: A Guide for Medical Device Manufacturers
- AAMI TIR 30:2011 – A Compendium of Processes, Materials, Test Methods, and Acceptance Criteria for Cleaning Reusable Medical Devices
- ASTM Designation E2314-03(2008) – Standard Test Method for Determination of Effectiveness of Cleaning Processes for Reusable Medical Instruments Using a Microbiologic Method (Simulated Use Test)
- FDA Guidance on Reprocessing of Reusable Medical Devices
Webinar Questions Answered
- Since an endoscope may possibly cause a rupture or penetration, shouldn’t it be considered for the critical category?
- Does the drying process matter when autoclaving? Should we be concerned when water dropplets are left in our device?
- What is a typical steam sterilization cycle time?
- What should be the approach taken to repeating biocompatibility testing post chemical disinfection validations?
- What is the best method for testing of residuals on silicon molded parts?
- During simulation of the cleaning validation and innoculating the device with soil and microorganisms, how do you determine what part of the device is to be exposed for the study? For instance, if part of the device is exposed to blood/tissue, do you expose only the part of the device that is being tested or do you expose the entire device? With the blood glucose monitoring machine, was the entire device innoculated with microogranisms or how did you determine where the pricked finger would be exposed at?
- What are the pros/cons of direct inoculation vs. sutures or strips?
- Do you differentiate between high, intermediate, and low level disinfection validation by having different acceptance criteria for each?
- We do not usually validate cleaning steps for bioburden reduction, because we validate the disinfection step for micro-organism reduction. Why is it necessary to validate cleaning for bioburden reduction?
- What resources or references do you recommend for selecting clinically relevant soils?
There is a risk that rupture or penetration can happen during the procedure and a possibility that contamination may spread across the blood barriers or sterile areas in the body. This contamination does not necessarily comes from the device used but may come from the underlying surface of the area where it is inserted. In this case, it is not the device that has an issue but the person performing the procedure. If this happens, doctors are ready for immediate management.
Should it be considered as critical device?
We have to take note that the areas where we place or insert the endoscope will determine whether the device is critical or not. Endoscopes inserted or used on GIT (Gastro-Intestinal Tract) are considered semi-critical because it does not only comes in contact with the mucosal surface but also being inserted on a non-sterile area of the body where number of microorganisms is present. Contamination may come from the intestinal lumen itself and not from the device used.
However, endoscopes used as diagnostic tools for the brain or other sterile areas of the body such as lungs or heart are required to be sterilized and are being classified as critical devices.
It depends- If you sterilize a device and it is intended for immediate use, say a “flash cycle” done during a medical or dental procedure, then drying is not required. If a product is sterilized and will be used after sometime or is intended for storage for future use, it is very important that the drying time should be included in the validation and subsequently included in each cycle for routine use. This is because any droplet of water left behind can be a pathway for any microorganisms/contaminants from the environment to enter the package/wrap/or even containment devices and subsequently may reach the device that was sterilized. We will inhibit microbial migration if the packaging including the device is completely dry.
There are 2 types of cycle in Steam Sterilization, One is Gravity Displacement cycle and the other is Pre-vacuum cycle (dynamic air removal) with 2 classifications. Please look at the following cycle time or exposure time classified under each type. These are the common exposure used by health care facilities.
|Gravity Displacement Cycle:||@121°C (250°F)||@132°C (270°F)||@135°C (275°F)|
|Wrapped instruments||30 min||15 min||10 min|
|Textile packs||30 min||25 min||10 min|
|Wrapped utensils||30 min||15 min||10min|
|Unwrapped items||3 min||3 min|
|Unwrapped mixed load||10min||10 min|
|Pre-Vacuum Cycle:||@121°C (250°F)||@132°C (270°F)||@135°C (275°F)|
|Wrapped instruments||4 min||3 min|
|Textile packs||4 min||3 min|
|Wrapped utensils||4 min||3 min|
|Unwrapped items||3 min||3 min|
|Unwrapped mixed load||4 min||3 min|
Note: The above exposure time are just recommendation based from what is commonly used in different health care facilities. Sterilizers vary in design and performance. The parameters you will use should be verified against the manufacturer’s instruction for specific load and configuration. The design of some medical devices will itself hinder air removal and steam penetration resulting to more difficult sterilization. Because of this, the manufacturer is in the best position to specify the condition or parameters necessary for steam sterilization for their particular device and this will be based from the parameters that was validated.
The rationale of repeating biocompatibility testing post chemical disinfection validations is to make sure that the process performed and the chemical used does not change the chemical composition of the device and does not produce any toxic byproducts as a result of its combination with the reagents/chemical used.
If in case the first biocompatibility testing post chemical disinfection validation fails, the cause of failure will be investigated. A biocompatibility testing of the device’ material prior to disinfection procedure will help in the assessment of the cause. If it passed the initial biocompatibility test, Investigation will be limited to its exposure to the chemical used.
Failure can be attributed to the chemical residues left behind after disinfection process or could be due to toxic byproduct produced as a result of the device exposure to the chemical used.
What should we do?
If the cause is chemical residues, a better or more astringent cleaning and disinfection procedure should be performed including a thorough rinsing process. Verify for the cleanliness and efficacy of the rinsing process.
If a toxic byproduct is produced by its combination, we should consider changing the chemical used and shift to reagents that are compatible with the device’ material composition.
How is it done?
Perform the validated disinfection procedure on the final device then submit the device for biocompatibility testing.
It depends on what type of soil that was used to perform the validation. Selection of soil depends upon the final use of the device and its intended environment. Simulation of the actual use is considered. All possible soil that can be attached to the device in its normal environment should be represented. If we know the soil, we can determine what appropriate test is applicable. Specific tests for carbohydrates, proteins, hemoglobin etc. can be performed if such residuals are suspected to be present in the device. A more general way of determining residuals either from those that I have mentioned and from the chemical used for cleaning and disinfection is TOC (total organic carbon testing). This will determine the total organic carbon remaining in the device due to residuals.
Q: During simulation of the cleaning validation and innoculating the device with soil and microorganisms, how do you determine what part of the device is to be exposed for the study? For instance, if part of the device is exposed to blood/tissue, do you expose only the part of the device that is being tested or do you expose the entire device? With the blood glucose monitoring machine, was the entire device innoculated with microogranisms or how did you determine where the pricked finger would be exposed at?
The parts that come in contact directly with the patient’s body will be our priority but we also have to include the parts that can be possibly soiled by the handlers and the patient itself where contaminations may come from.
Basically, we inoculate the part that is exposed to the blood and tissue with emphasis on the most challenging areas and also include other underlying areas which could be a pathway for spread of contamination either from a patient or the handler.
With regards to BGMS (Blood-Glucose Monitoring System), we don’t inoculate the entire device but only the challenging areas that come in contact with the patient and handler. These areas should be enough to represent the whole device. The following areas of concern and should be inoculated will be: part of external surface, buttons, crevices, screws (if present) where residuals can be trapped and most importantly the “test port” area where collection of blood for test, takes place.
We have to consider that some patients can be bleeders and may accidentally spread blood to any part of the device, make sure that this is also covered and adequately addressed.
Strips and threads (sutures) are forms of the biological indicators commonly used in sterilization validations and exposures. They easier to use, are retrievable and there’s no need to incubate the device to audit sterility. By just testing the BI is enough to determine whether the devices exposed to the process are sterile or not. One of the disadvantage of using these forms of BI will be the size and the possibility that they may be blown away and may not be recovered for testing (although it doesn’t happen all the time).
However, devices that can’t be inoculated with strips and are considered very critical should be inoculated directly with a microbial suspension. Implantable devices require direct inoculation. In this case, the device will be incubated for the required number of days to determine whether it is sterile or not. If you don’t have enough samples to use for the validation, you will have to wait until the incubation period is completed before another cycle can be initiated. Thus, validation takes longer time to perform.
Yes and this acceptance criteria should be achieved for each type of disinfection. Although at one point these different levels of disinfection shares a common criteria of 6 log reduction of a mixed suspension of Pseudomonas, Staphylococcus, E. coli and representative of Klebsilla-Enterobacter group, additional criteria is included to differentiate each levels.
Low-level disinfection will only have the above mentioned criteria.
Intermediate-level disinfection: aside from what is mentioned above will have additional 3 log reduction of Mycobacterium species.
High-level disinfection: aside from what is mentioned above will have additional 6 log reduction of Mycobacterium species.
Q: We do not usually validate cleaning steps for bioburden reduction, because we validate the disinfection step for micro-organism reduction. Why is it necessary to validate cleaning for bioburden reduction?
If you’re doing a cleaning and disinfection validation, it is not necessary to determine the bioburden reduction from the cleaning process or step because it will be covered under the disinfection validation. For a cleaning validation (cleaning procedure alone), FDA puts more weight on the determination of soil residuals to prove the efficacy of the cleaning process, rather than bioburden reduction because some of the cleaning agents can potentially kill microorganisms but not effective in removing redundant soils. Although counts of the viable microorganisms are useful for manufacturer’s validation studies, it should not be used as a sole marker for cleaning. It is recommended that soil residual determination will be performed as well. Whether we use both will depend on our good judgment and discretion. Other standards recognized by the FDA still consider bioburden reduction as a tool in the assessment of cleanliness.
Validating the cleaning process for bioburden reduction is still recommended by AAMI standards.
AAMI TIR 30 = soils
AAMI TIR 12 = microbial markers
AAMI ST 79 = soil components to be tested to assess efficacy of cleaning process