What is a Clean Medical Device?

By: Breanna Turman, PhD

Reusable medical devices can become heavily soiled and contaminated during use. Devices may contact bodily fluids such as blood or mucus, bone or tissue fragments, and high levels of microorganisms such as those found in the gastrointestinal tract. Devices must then be cleaned and often disinfected or sterilized to remove the soil and microorganisms prior to reuse to prevent exposing patients to potentially harmful microorganisms. Errors in this reprocessing procedure, including insufficient cleaning of medical devices have been associated with numerous healthcare-associated infections (HAIs).^1-3 These and similar reports have led to multiple scientific studies to determine what it means for a reusable medical device to be sufficiently clean.

The currently accepted definition of a clean medical device according to ANSI/AAMI standard ST98 is a device that is free from visible soil and contains contaminants at or below the limits provided in Table 1.⁴

Table 1. Limits for Common Contaminants on Clean Reusable Medical Devices

*According to ANSI/AAMI standard ST98

These contaminants are representative of the types of soil that are expected to be found on a medical device following use. This definition of ‘clean’ is based upon studies examining clinically used devices before and after cleaning.^5-8 Given the support from scientific evidence and the specific measurable outcomes, this definition is currently one of the best from a scientific perspective. Yet, translating this scientific definition to clinical practice can be difficult.

Cleaning verifications to verify cleaned devices in clinical settings meet the contaminant levels specified in ANSI/AAMI standard ST98 are recommended.^{4, 9-11} Rapid tests for common medical device contaminants have been developed to help reprocessing departments meet these recommendations. However, some rapid tests may be cost prohibitive, and others may only confirm the presence of a contaminant but may not quantify the levels of residue. Further, in busy reprocessing departments with stringent time constraints, it is not feasible to verify the cleanliness of every device, especially for difficult to reach areas or complex devices.⁹ For these reasons, the scientific definition for a clean medical device may not always be applied in clinical settings. A busy reprocessing department may instead utilize a more functional definition of clean in which a clean device refers to a device that has been reprocessed according to the validated procedure and is free from visible soil.

While this definition of clean may be more feasible to execute, it has its downfalls. Human error and procedure non-compliance in medical device reprocessing are well documented.^12-16 According to the functional definition of clean, errors in the reprocessing procedure result in an unclean device. However, these errors are not always recognized meaning an unclean device could be released for use or further reprocessing. The second downfall of this functional definition is that visual examination is subjective and highly dependent upon lighting, device design, individual visual acuity, and whether any aids (microscope, magnifying glass etc.) are used. Visual examination is also not very sensitive. Even if all surfaces of a device can be accessed for examination, microscopic levels of soil can still be left behind.^17-19 This small amount of soil may or may not be a large issue for some non-critical devices. However, for other devices, even small amounts of residual soil can hinder device reprocessing and functionality.

In addition to being cleaned, many reusable medical devices are disinfected or sterilized to kill potentially harmful, microorganisms on the device. Residual soil on the device following cleaning can interfere with disinfection and/or sterilization processes by inactivating the disinfectant/sterilant or by shielding microorganisms from contact with the disinfectant/sterilant.^{8, 20-24} Surviving microorganisms on the device can infect patients or grow into biofilms that are notoriously difficult to remove and more resistant to disinfection and sterilization than non-biofilm bacteria.^{9, 17, 22-24} Residual soil can also be fixed or glued to the device by chemical disinfectants or high heat making it more difficult to remove the next time the device is cleaned.^{17, 25} Over time, repeated insufficient cleaning leads to continual soil and biofilm accumulation on the device.²⁶ This accumulated soil and biofilm are not only difficult to remove, but could also affect the functionality of some devices. For example, accumulation of residual soil in the screw mechanism on surgical scissors could make them difficult to open and close. Similarly, improper cleaning has been associated with ultrasound probe failure.^27-29 Residual soil or biofilms on the lens of ultrasound probes can negatively impact the image quality and potentially diagnostic outcomes by scattering or blocking the sound waves emitted by the probe.^{27, 28} Removing the residue or biofilm to restore optimal probe function may require harsh cleaning and scrubbing that can cause probe damage requiring costly repair or replacement.^{27, 29}

Residual soil on medical devices following improper cleaning can have consequences for device functionality as well as disinfection and sterilization. Therefore, it is imperative for medical devices to be clean prior to use or further reprocessing. However, the gap between the scientifically accepted definition and the functional definition that can be applied in a clinical setting represents a barrier to ensuring devices are cleaned properly. By bringing automation into the cleaning process, healthcare facilities can help address many of these challenges with a more consistent, repeatable workflow designed to support cleaner devices, reduce reprocessing variation, and help ensure every reusable device is clean every time.

References:

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