How Ultrasonic Cleaning Enhances Patient Safety

Cleaning systems for medical instruments. Ultrasonic cleaner

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The cleaning and disinfecting of reusable medical instruments and devices is a crucial process in patient safety for health care facilities. Sterile processing departments are often overlooked in their importance to the entire facility, but infection preventionists need to have a working understanding of all the steps, various types of equipment involved, and potential points of risk for disease transmission that can occur.

Ultrasonic cleaners are utilized in sterile processing departments (SPD) to automate instrument cleaning. They are critical for instruments that may be challenging to manually clean effectively, such as devices with jagged edges, hinges, or serrations. The manufacturer’s instructions for use (IFU) always indicate if ultrasonic cleaning is required or appropriate for devices.

The instrument-cleaning process starts at the point of use, with the appropriate enzyme or pretreatment applied immediately after the procedure. Instruments must remain wet and transported in a rigid, closed container with appropriate biohazard labeling. Transportation to the SPD should occur immediately after the point-of-use treatment has been applied to prevent the instruments from drying. If bioburden is allowed to dry on the instruments, the cleaning becomes more challenging, potentially impacting the disinfection and sterilization steps in the process.

Once instruments are received in SPD, the decontamination process continues with rinsing, flushing, soaking, inspection, and any manual cleaning indicated by the IFUs. Then, the instruments are ready for ultrasonic cleaning. During manual cleaning, the technician must follow the care instructions for each instrument, ensuring the appropriate brushes are used, any instruments with hinges or moveable parts are opened and cleaned, and visible bioburden is removed.

Ultrasonic cleaners create ultrasonic sound waves to cause cavitation and remove bioburden.¹ Cavitation is the process by which microscopic bubbles in the detergent grow and implode, causing the release of tissue and contaminants from the instrument surface.² This process allows the effective cleaning of instruments with details such as small openings and hinges that are challenging to clean manually. The microscopic bubbles can penetrate these areas and remove any remaining tissue or contamination.

For lumened instruments, ultrasonic cleaners can connect to the instruments and provide the same cavitation process for both the interior and exterior. Additionally, the flushing and rinsing steps are incorporated into the machine’s process, ensuring full cleaning of those lumened devices that are so challenging to clean manually.

The appropriate cleaning agent must be used based on the ultrasonic cleaner and instrument IFUs. The type of cleaning agent used must meet several key considerations. It must be compatible with the cavitation process, work in different types of water quality, and be nontoxic, low-foaming, and free-rinsing.¹ Water temperature also impacts the cleaning agent’s effectiveness.

Personnel should receive appropriate training and competencies for the use of ultrasonic cleaners. Sterile processing staff must clearly understand their role and its importance to patient safety. All steps of the decontamination process must be completed with accuracy and attention to detail. This can be challenging when the work is repetitive and there is pressure to quickly turn over instruments for a busy operating room schedule.

Some key points that need to be covered in training include how to properly load instruments in the cleaner to ensure as much surface area is exposed, for example, with hinges open. Instruments should not be overcrowded or overweight for the cleaner. Additionally, the visual inspection of instruments for signs of damage, bioburden, staining, or pitting during the manual cleaning is important to ensure any worn or damaged instruments are removed from use.

Another consideration for the IP when thinking about ultrasonic cleaning, or any process in SPD, is the facility water management program. Water quality for reprocessing medical devices. Water quality can directly impact the ability of sterile processing to perform adequate cleaning and disinfection of instruments. The water management program must be managed by a multidisciplinary team, which includes facilities management, infection prevention, and sterile processing. Recent water quality standards have identified key areas where the water management programs need to focus and where to implement routine water quality testing.

Poor water quality can contribute to many factors that can negatively affect the patient. For ultrasonic cleaners, in particular, water hardness, temperature, bacterial and endotoxin levels, ion levels, and sedimentation would all impact the machine's effectiveness.

For example, corrosion caused by water hardness or sedimentation can contribute to the device's malfunction. If an instrument is not cleaned and disinfected, a patient could be exposed to endotoxins or microorganisms that can contribute to infection. Hardness can impact the washer device itself and leave residue on instruments.

When discussing water management, 3 types of water are important to understand: utility water, critical water, and steam.³ Utility water, which comes from the facility’s connected water supply, is typically used for initial steps in reprocessing, except for a final rinse with critical water. Critical water has been treated to remove bacteria and endotoxins, has the approved pH levels, and meets other specifications. Some ultrasonic washers may perform the final rinse automatically, and critical water would be used for that rinse. The post-wash rinse is essential to remove any residual cleaning agent and contaminants. The manufacturer’s IFUs must be reviewed for the device to ensure the appropriate water is used for each cycle.

SPD staff must maintain logs of ultrasonic cleaners’ required maintenance and quality testing. The specific machine IFUs will indicate the type of maintenance and schedules. This may include device calibration, test strips for detergent levels, or testing for protein levels. The IP should review those logs when performing rounds in SPD to ensure completeness.

Studies have compared the effectiveness of manual cleaning to ultrasonic cleaning. Most studies have found that compared to manual cleaning, ultrasonic cleaning is more effective at removing residue from instruments, particularly those that are harder to clean.² As medical instruments become more complex, manual cleaning becomes more difficult. However, manual cleaning is still considered best practice in the first step of the decontamination process and should not be skipped over instead of ultrasonic or automated cleaning alone. Manual cleaning of larger debris is critical for the ability of the ultrasonic cavitation process to be effective.

Are there any cons to ultrasonic cleaning? The first consideration is the cost of the equipment. However, given the benefits over manual cleaning alone, that can easily be countered with a risk-benefit analysis. Second, it is important to review the IFUs for any instruments that will be placed in the cleaner. Some materials are incompatible with ultrasonic cleaning and could damage the machine or the instruments. While not a barrier, SPD staff must have the proper training and competencies on the equipment to ensure all aspects of the IFUs are adhered to.

For many IPs, sterile processing is an intimidating and challenging area to develop expertise in, especially as a novice IP who has not worked in a perioperative field. It is important for the IP to collaborate with SPD leadership, make frequent rounds in the department, talk with staff about their processes, and reach out to fellow IPs to ask questions.

References

1. Guide to ultrasonic cleaning of medical devices: how ultrasonics work and more. Steris. May 31, 2024. Accessed February 14, 2025. https://www.steris.com/healthcare/knowledge-center/sterile-processing/guide-to-ultrasonic-cleaning.
2. Ultrasonic cleaning vs. manual cleaning. February 28, 2024. Ultra Clean Systems, Inc. Accessed February 15, 2025. https://ultracleansystems.com/ultrasonic-cleaning-vs-manual-cleaning/#:~:text=Ultrasonic%20cleaning%2C%20however%2C%20has%20proven,placed%20in%20an%20ultrasonic%20cleaner.
3. What hospitals need to know: Using water during processing of medical instruments. ECRI. April 26, 2024. Accessed February 19, 2025. https://home.ecri.org/blogs/ecri-blog/what-hospitals-need-to-know-using-water-during-processing-of-medical-devices.