What type of instruments should be sanitized using an ultrasonic cleaner?

Medical and surgical instruments in a variety of sizes and complexity can pose challenges when it comes to cleaning, disinfecting and sterilizing them after use.  An ultrasonic cleaner is an ideal tool for the first step in this three step process to protect medical personnel and patients from possible infection due to pathogens that remain on the instruments after a procedure.

The Ultrasonic Principle

Ultrasonic cleaners work on the principle of cavitation whereby ultrasonic transducers create billions of minute air bubbles in an ultrasonic cleaning solution.  These implode with violent force when they come in contact with objects placed in the solution and strip away contaminants without damaging the objects.  When medical and surgical instruments are properly prepared for the ultrasonic cleaning step the process is fast, thorough and efficient.

Pre-prep is important, according to the Association of PeriOperative Registered Nurses (AORN) Recommended Practices Committee, which states that “initial instrument decontamination should begin immediately after any invasive procedure.*” Washing and wiping to remove gross contaminants is important before they dry and more strongly adhere to the instruments.  If instruments are batched before the ultrasonic cleaning step they should be immersed in a sterile solution such as an enzyme soak to further protect against residual contaminants drying on them.  Use brushes to clean the interior of cannulated or lumened instruments.

Throughout the pre-prep and entire process personnel must be careful to avoid cuts and scratches from sharp or pointed instruments.

Ultrasonic cleaners such as the 1.8 gallon capacity Elmasonic S70H and 3.75 gallon capacity Elmasonic S150 available from Tovatech are ideal for cleaning medical and surgical instruments up to 18 inches long.  Both operate at 37 kHz ultrasonic frequency to quickly and safely remove the most stubborn contaminants.  Both offer automatic degassing for fresh cleaning solutions and a sweep function to optimize ultrasonic energy distribution throughout the bath.  Cleaning time can  be programmed on user-friendly operating panels.

A Suggested Ultrasonic Cleaning Procedure

In all cases manufacturers’ instructions should be followed when using an ultrasonic cleaning process. These are representative steps.

Fill the ultrasonic cleaning tank with an approved medical instrument cleaning solution such as CLN-LR012 available from Tovatech following dilution instructions provided.  Turn the cleaner on to start the degassing process.  This step removes entrained air in new solutions that interferes with the efficiency of cavitation and takes approximately 10 minutes.

In the meantime:

• Segregate instruments by alloy or composition to avoid potential damage (Chromium plated instruments should not be cleaned ultrasonically)
• Instruments with movable parts should be disassembled to facilitate cleaning
• Place the instruments the ultrasonic cleaner’s mesh basket, taking care that they do not come in contact with each other
• Cannulated or lumened instruments should be positioned to insure interiors are wetted with the cleaning solution.  In some instances placing them on an angle will facilitate this
• Set the control panel per manufacturers’ instructions and start the cleaning process

At the end of the cycle, remove the instruments from the ultrasonic cleaning bath and thoroughly rinse them to remove all traces of the cleaning solution.  Deionized water rinses will avoid spotting. If the instruments are not to be immediately disinfected and sterilized be certain that they are thoroughly dried and protected. Part reassembly can occur after sterilization.

Procedures should be in place to guide the replacement of used ultrasonic cleaning solutions.  In some instances it is recommended that solution be drained and tanks thoroughly cleaned and dried after each ultrasonic cleaning cycle.  Most solutions available today are biodegradable, which facilitates disposal but local authorities should be consulted on proper practices.

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What instrument cleaning practices are in use at your healthcare facility?  Are these practices spelled out in the operations manual?

* “Recommended practices for the care and cleaning of surgical instruments and powered equipment” AORN Journal, January 1997

Cleaning is the most important step in reprocessing a medical device. Without adequate cleaning, disinfection and sterilization can’t be performed effectively. Ultrasonic cleaning can be particularly useful for hard to reach areas on a device, such as on fine serrations or box lock joints, but it can also be gentle on delicate instruments such as microsurgical and ophthalmology devices.

How Does Ultrasonic Cleaning Work?

The ultrasonic cleaning process uses mechanical vibrations to agitate a solution to aid in the removal of soil from surfaces, and in some cases inside lumens, of surgical devices. The sound waves in the liquid produce microscopic implosions of bubbles that collapse on contact with surfaces, creating a vacuum-like scrubbing action dislodging soil from surfaces; this effect is called cavitation. The cavitation then removes bioburden from the surface of the items submerged in the chamber.

Ultrasonic cleaning systems provide effective cleaning using a combination of three parameters:

• Cavitation
• Flow/Sonic Irrigation
• Detergents

The right combination of these parameters provides an efficient cleaning system for delicate and difficult-to-clean medical devices such as Minimally Invasive Surgical (MIS) instruments, laparoscopic devices and robotic surgical attachments.

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Cavitation and Ultrasonic Cleaners

The efficacy of the cavitation process is dependent on the design of the ultrasonic system and particularly on the ultrasonic frequency (measured in kilohertz, kHz) and power density. When buying an ultrasonic cleaner, you want to ensure that the frequency and power density are appropriate for medical devices you’ll be processing by checking with your most common device IFUs.

How the cavitation bubbles are generated is also important. For example, older technology uses metal transducers while newer designs use ceramic transducers that are gentler on devices. Some systems mount the transducers to the bottom of the tank which is effective at removing soil on a single layer of instrument trays. Since the ultrasonic waves are coming up from the bottom, the cavitation will be more effective imploding on the instrument surfaces placed on the first, most immediate tray that it will encounter, which will not be the case for the instruments placed on the second or third tray. Large ultrasonic cleaners however, mount transducers to the sides of the tank, allowing multiple layers of trays to be cleaned effectively.

Flow and Sonic Irrigation

Some ultrasonic cleaners also offer flow, or sonic irrigation. Flow of solution through a device allows for more efficient cleaning of the internal channels of lumened or cannulated devices, while the use of pressurized flow can provide additional mechanical cleaning.

Lumened or cannulated devices cannot be expected to be cleaned in standard ultrasonic cleaning systems. STERIS Innowave Ultrasonic Irrigators have sonic irrigation capabilities, allowing the ultrasonic energy and cavitation to work on both the exterior and interior of the devices processed.

Some cleaning validations for specific complex surgical instruments require a minimal pressure for the flow, which also becomes a key parameter to ensure the bioburden is removed from within the instruments. The combination of a high pressure flow and the ideal ultrasonic cavitation does result in an efficient method to ensure detailed and complex instruments are reprocessed effectively.

Detergents for Ultrasonic Cleaning

Choosing a cleaning chemistry is an important component of the ultrasonic cleaning process. These detergent-based products should provide cleaning, be effective over a range of different water qualities, not harm the device while simultaneously protecting the device from damage over time, be easy to rinse and be compatible with the ultrasonic cleaning system. Prolystica Instrument Cleaning Chemistries go beyond cleaning to meet all these requirements.

Consider using a chemistry that’s specifically formulated and designed for ultrasonic cleaning. The Prolystica HP Enzymatic Detergent is formulated specifically for automated washing, designed with a low-foam profile for use in sonic washers or washer/disinfectors.

Benefits of Ultrasonic Cleaning

Many devices in the surgical environment today are intricate, delicate and complex in design. Without a form of automated cleaning, Sterile Processing Department staff must clean the nooks, crannies and hinges by hand, consuming their valuable time.

Ultrasonic cleaning provides a safe, effective way to clean multiple surgical instruments at once, from delicate ophthalmic and laparoscopic devices to heavy orthopedic instruments. The ultrasonic cleaning process allows for scrubbing action to reach small crevices, irregular surfaces and internal passages, without damaging the intricate device. Ultrasonic washers are designed to dislodge challenging soils from the surface and lumens on instruments and provide consistent cleaning results throughout the washer chamber.

Ultrasonic Cleaning Recommendations

Ultrasonic cleaning systems should be installed, used and maintained in accordance with manufacturer's instructions. This will include the use of specific detergents for cleaning, and adherence to recommended preventative and routine maintenance.

The following recommendations are given for the safe and effective use of ultrasonic cleaning systems:

• Gross soil should be removed (pre-cleaned) from the device prior to cleaning in the ultrasonic cleaner and lumens brushed/flushed.
• Surgical instrument cleaning chemistries should be designed for use in ultrasonic systems
• Degassing of freshly prepared cleaning solution is generally recommended before processing devices, following manufacturer's instructions.
• The device instructions for use should be consulted to ensure compatibility. Some devices/materials of construction (such as certain types of adhesives on optical components or rubber) are not recommended for sonication due to the risk of damage to device components. Devices that contain metals such as brass, copper, aluminum, or chrome-plate may not be compatible if mixed with other device materials such as stainless steel.
• Cleaning solutions should be frequently changed, preferably with each use and always before processing ophthalmology instruments.
• Periodic verification testing of the sonic unit is recommended to confirm that the cleaning process is functioning properly. This will include daily maintenance and periodic service maintenance, or the use a cleaning verification indicator like the VERIFY Ultrasonic Indicator.

A combination of all these variables in ultrasonic cleaning systems can provide an optimal cleaning process for devices.

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