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Reprocessing ♲ of Medical Devices: Cleaning, Disinfection, And Sterilization Validations

Reusable medical devices are instruments and tools designed for multiple uses on different patients after undergoing reprocessing procedures that include cleaning, disinfection, and sterilization. Examples of these devices include surgical instruments, endoscopes, dental tools, and certain types of catheters. The ability to reuse these devices provides significant economic and environmental benefits by reducing medical waste and lowering healthcare costs. However, the reuse of medical devices also introduces the critical responsibility of ensuring that they are thoroughly cleaned, disinfected, and sterilized to prevent cross-contamination and infections.

Importance of Cleaning, Disinfection, and Sterilization

  • Patient Safety: The primary goal of reprocessing reusable medical devices is to ensure patient safety by eliminating pathogens that could cause infections. Inadequate cleaning, disinfection, or sterilization can lead to healthcare-associated infections (HAIs), which can have severe consequences for patient health and safety.
  • Regulatory Compliance: Regulatory bodies such as the CDSCO, FDA, CDC, and international organizations like ISO, ASTM provide stringent guidelines and standards for the reprocessing of reusable medical devices. Compliance with these regulations is essential to ensure the devices are safe for use and meet the necessary quality standards.
  • Device Longevity and Functionality: Proper reprocessing not only ensures safety but also helps maintain the functionality and longevity of medical devices. Effective cleaning, disinfection, and sterilization prevent the accumulation of residues and contaminants that could degrade the device materials and impair their performance.
  • Operational Efficiency: Efficient reprocessing procedures enable healthcare facilities to quickly turn around medical devices for reuse, ensuring that they are readily available for patient care. This efficiency is crucial for the smooth operation of healthcare services, particularly in high-demand environments such as hospitals and surgical centers.

Regulatory Approvals and Labeling Compliance for Reusable Medical Devices

Although the devices are classified under low risks but still the are tagged with Reusable term. With the increasing focus on patient safety and infection control, reusable medical devices or reprocessed medical devices are now subject to stringent regulatory approvals and labeling compliance requirements. Manufacturers must adhere to these regulations to ensure their devices are safe for reuse and meet the necessary quality standards.

Regulatory Approvals

Regulatory bodies such as the U.S. Food and Drug Administration (FDA), European Medicines Agency (EMA), and national agencies like the Central Drugs Standard Control Organization (CDSCO) in India, require rigorous testing and validation for reusable medical devices. These approvals encompass various aspects, including:
  • Design and Manufacture: Ensuring devices are designed and manufactured to withstand multiple reprocessing cycles without compromising functionality or safety.
  • Reprocessing Instructions: Providing detailed, validated instructions for cleaning, disinfection, and sterilization.
  • Risk Management: Implementing risk management processes to identify and mitigate potential risks associated with reprocessing.
  • Validation and Testing: Conducting comprehensive validation and testing to demonstrate that reprocessing procedures are effective and repeatable.

Labeling Compliance

Labeling compliance is another critical aspect for manufacturers of reusable medical devices. Proper labeling ensures that healthcare providers have the necessary information to safely and effectively reprocess and reuse medical devices. Key labeling requirements include:
  • Reprocessing Instructions: Clear, concise, and validated instructions on how to clean, disinfect, and sterilize the device.
  • Warnings and Precautions: Information about any potential risks or limitations related to reprocessing.
  • Compatibility: Details about the materials and chemicals that can be used during reprocessing to avoid damage to the device.
  • Shelf Life: Information on the expected number of reprocessing cycles the device can safely undergo and its overall shelf life.

Considerations in Reusable Device Design

The term “reprocessing” can have many meanings, for the purposes of this article the term will refer strictly to the cleaning and disinfection or sterilization necessary to render a medical device safe for reuse.

Reusable devices face significant design challenges that single-use devices do not. A design engineer must think about how the device will perform not only during the first use, but for every subsequent use. Many medical devices need to be able to function safely after hundreds of cleaning and disinfection or sterilization cycles; these devices must therefore be designed to comfortably withstand the stresses of the reuse procedure. Additionally, reusable devices need to be designed so that they may effectively be rendered safe for reuse by either health-care staff or patients at home. If the process is too difficult or complex, there is a possibility that the device will not be fully rendered safe for reuse.

A thorough understanding of device cleaning, disinfection, and sterilization issues is therefore essential in the design phase of any reusable medical device. Devices that are designed with the eventual reuse parameters in mind generally have a quicker and easier path through the validation process. Conversely, devices that prove very difficult to clean or disinfect often must be redesigned, resulting in delays and/or cost overruns. Thus, reusable medical devices should be designed not only to facilitate the use of the device, but to facilitate the eventual reuse as well.

The Reuse Validation Process

The ultimate goal of device reprocessing is to render a medical device safe for further human use. Typically, two steps are involved in device reprocessing: cleaning and either disinfection or sterilization. The validation process begins with the creation of a reprocessing procedure based on the intended clinical use and design of the device. Next, the device is purposefully contaminated and challenged with a worst-case level of soil, then run through the reprocessing step that is being validated. Soil residues include organic soil such as proteins, hemoglobin, and endotoxins, inorganic soil, and biological soil in the form of suspensions of microorganisms.

If the reuse procedure adequately removes the soil and all reprocessing criteria are passed, then that procedure is validated for use. Appropriate documentation must then be created for the end user, describing in detail how to reprocess the device.

Cleaning is always the first step in reprocessing and is defined by the FDA as removal of soil residues and is a necessary step prior to reuse of any medical device. To validate the cleaning process, the device is inoculated with soil, cleaned using the recommended cleaning procedure, and then residuals (any soil remaining on the device) are recovered and measured. The acceptance criteria to validate the procedure are: a visually clean device; 3-log reduction in microorganisms; protein levels <6.4 ug/cm2; hemoglobin< 2.2 ug/ cm2; carbohydrate <1.8 ug/ cm2; endotoxin <2.2 ug/ cm2.

Disinfection is defined as using physical or chemical means to kill microorganisms. This is frequently accomplished through the use of chemical disinfectants, or via thermal disinfection (the application of high temperature water). A disinfection process is considered to be validated if the device is visually clean and a 6-log reduction in microorganisms can be shown.

Sterilization is a process that renders a device free from viable microorganisms. The level of sterilization is defined by Sterility Assurance Level, or SAL, which is the probability that a device is not sterile. For example, an SAL of 10-6 indicates a 1 in 1 million possibility that the device is non-sterile. Sterilization can be achieved in a number of ways, but the most common methods of sterilization are steam, dry heat, hydrogen peroxide, ethylene oxide, and radiation. The acceptance criteria for sterilization of non-critical devices (those that do not penetrate the body) is 10-3, and the acceptance criteria for critical devices is an SAL of 10-6.



Cleaning

Disinfection

Sterilization

Manual: Cleaning with or without use of brushes or specialized tools

Low Level: Kills most vegetative bacteria, some viruses and some fungi

High Temperature: Moist heat/steam or dry heat

 Mechanical/Automated: Ultrasonic or medical washers

Intermediate Level: Kills vegetative bacteria, viruses, fungi, and mycobacterium

Low Temperature: Ozone

Chemical: Liquid sterilants, Hydrogen Peroxide

High Level: Kills all microbial organisms – potential to render device sterile

Gas: Ethylene Oxide

Thermal: Disinfection via thermal applications under 100C

Radiation: Gamma, e-beam

To validate a disinfection or sterilization process, a device is inoculated with a known count of microorganisms and then treated with the recommended procedure. Following treatment, any remaining viable (live) microorganisms are recovered, cultured, and colonies are counted. If there is an adequate reduction in microorganisms (or if the required SAL is achieved), then the disinfection or sterilization procedure is validated.

To understand the requirements for cleaning, disinfection, and sterilization validations, it is also necessary to be aware of the different classifications of reusable medical devices. The more invasive the device, the more stringent the reprocessing procedures must be. Noncritical devices, which only make contact with intact skin, require cleaning and low or intermediate-level disinfection. Semicritical devices contact mucous membranes but not the bloodstream, and require cleaning and high-level disinfection. Critical devices are those which contact the bloodstream or other sterile areas of the body. Given the high possibility of infection if any microorganisms are introduced into these areas, critical devices must be cleaned and then sterilized to an SAL of 10-6.


Design Considerations

There are three main design aspects that must be considered: material selection, physical design, and total system design. The materials selected for use in a device must be biocompatible; material selection must take into account the use of the device and the potential of the material to leach toxic substances. Additionally, some materials may release toxic byproducts when exposed to cleaners or disinfectants. Semi-critical or critical devices that will most likely be exposed to strong cleaning or disinfecting agents should take this into account during material selection.

Material Selection

Porous materials are often prone to retaining high levels of soil residuals and can be difficult to clean thoroughly. A highly porous material may also retain residual amounts of a cleaning or disinfecting agent that can then harm patients during use. It is also important to consider the limitations of both metal and polymer materials. Metals may be scratched by brushes, leading to a greater retention of residuals. Polymeric coatings over metals can be adversely affected by ultrasonic or mechanical cleaning, potentially resulting in leaching of coating material. Polymer materials also react to some chemicals, and can become distorted or easily scratched. Finally, consider limiting the use of adhesives or lubricants, as these may become toxic when exposed to cleaning, disinfecting, or sterilization agents.

Physical Design

The physical design of a device can put additional constraints on the cleaning process and is one of the most important considerations in device engineering. The size and shape of components can have a large effect on the ease of reprocessing. Long interior channels, lumens, or small openings can be difficult to clean, as a brush often needs to be able to pass through openings to reach and clean interior spaces. To facilitate cleaning of small interior spaces, some device designers create custom brushes or cleaning tools. If the interior of the device may become exposed to blood or other bodily fluids, consider adding an open port that facilitates flushing the device’s interior.

Rough or discontinuous surfaces can be difficult to clean, as can sharp angles. This can result in an increased capacity to collect microorganisms. If the device must be disassembled and reassembled, small detachable pieces may be misplaced easily. The process of disassembly and reassembly should be fairly intuitive; if it is too difficult or complex, health care practitioners or patients will be reluctant to perform the necessary steps.


Total System Design Considerations

Once materials and the physical design are planned, the device as a total system must still be examined. If the device will be composed of multiple materials, the question of whether these materials will interact must be considered. For instance, stainless steel parts combined with aluminum, brass, copper or chrome can create an electrochemical reaction.

Additionally, consider whether electronic parts are adequately protected from potential reprocessing agents (such as liquids.) Finally, examine the potential long-term effects of reprocessing. If the cleaning and disinfection or sterilization cycle is repeated, will the device eventually be rendered unusable, unsafe for patient use, or incapable of further reprocessing?



Device Category

Treatment Options

Criteria

Critical (Must be Sterile)

Sterilization

Sterilization: SAL – 10-6

Semi Critical (Sterile or Disinfected)

Sterilization or High Level Disinfection

Sterilization: SAL – 10-3

Disinfection: 6 Log Reduction

Non Critical (Does not need to be sterile)

Cleaning and Disinfection

Cleaning: Removal of residuals, visually clean

Sterilization: SAL – 10-3

Disinfection: 3 Log Reduction

Reusable Device Category

Typical Steam Sterilization Cycle Time for Reprocessing of Medical Devices

Steam sterilization, also known as autoclaving, is a common and highly effective method used to reprocess reusable medical devices. The cycle time for steam sterilization can vary depending on several factors, including the type of device, the configuration of the load, and the specific requirements of the sterilization process.

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. The following cycle time or exposure time classified under each type are described below. These are the common exposure used by health care facilities.

Gravity Displacement Cycle for Reprocessing of Medical Devices

Gravity displacement sterilization is a type of steam sterilization used in autoclaves where steam displaces the air in the chamber through gravity. This method is particularly effective for sterilizing solid instruments and devices without lumens or complex shapes.

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

12 min

3 min

3 min

Unwrapped mixed load

15 min

10min

10 min



Pre-Vacuum Cycle for Reprocessing of Medical Devices

The pre-vacuum cycle, also known as a dynamic air removal cycle, is a method of steam sterilization used in autoclaves that employ a vacuum pump to remove air from the chamber before steam is introduced. This process ensures better steam penetration, making it particularly effective for sterilizing complex and porous medical devices.


Pre-Vacuum Cycle:

@121°C (250°F) 

@132°C (270°F)

@135°C (275°F)

Wrapped instruments

15 min

4 min

3 min

Textile packs

15 min

4 min

3 min

Wrapped utensils

15 min

4 min

3 min

Unwrapped items

12 min

3 min

3 min

Unwrapped mixed load

12 min

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.

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