October 8, 2020
With the increased use of minimally invasive surgical techniques, tools and instruments that can’t be cleaned easily or sterilized with high temperatures are becoming more common. Endoscopic instruments are hard to clean, and many are temperature sensitive. Tools such as those for collecting biopsies have complicated shapes, and may have features such as hinges that can harbor pathogens and contamination. Manual cleaning can remove visible contamination, but can easily miss hidden material in the cracks of hinges or inside holes and passages. Soaking in disinfectant kills off some of the microbes, but the disinfectant often does not penetrate into cracks and orifices. When steam sterilization is not possible because the high temperature damages components such as fiber optics, such contaminating organic matter can cause infections and transmit disease.
Medical ultrasonic cleaners can help address these issues. Using ultrasonic sound waves in a cleaning solution, the cleaners can dislodge contamination and particles from medical instruments and tools. Cleaning performance is excellent but does not, by itself, guarantee that an instrument or tool is sterile. When a disinfectant is added to the cleaning solution, the action of the ultrasonic sound waves forces the liquid into crevices and holes where it can kill microbes on contact. The sound waves clean the surfaces and the dislodged matter can be rinsed away, leaving the disinfected parts. The website “Infection Control Today” gives details of the type of disinfectant that work best and describes when ultrasonic cleaning is recommended by some manufacturers of re-usable medical instruments.
How Ultrasonic Cleaners Help Clean and Sterilize Complex Medical Instruments
Ultrasonic cleaners work by using an ultrasonic transducer to convert a high-frequency electrical signal to ultrasonic sound waves in a liquid. The tank-mounted transducer vibrates in tune with the electrical signal to create sound waves throughout the cleaning bath. Microscopic cavitation bubbles are created in the low-pressure troughs of the ultrasonic waves and the bubbles collapse when subjected to the high pressure of the compression sound wave peaks.
With a commonly used frequency such as 38 kHz, cavitation bubbles are created and collapsed 38,000 times each second. Each collapsing bubble creates a powerful suction effect that dislodges microbes and contaminating particles from the surfaces of the parts to be cleaned. Once dislodged, microbes are fully in contact with the disinfectant of the cleaning solution and are killed. An ultrasonic cleaner generates millions of cavitation bubbles each cycle so that cleaning is rapid and complete. Together with a disinfecting cleaning solution, an ultrasonic cleaner is an effective alternative to steam sterilization.
How to Match the Ultrasonic Cleaner to the Cleaning Task
Key factors to consider when selecting a medical ultrasonic cleaning system are the size of the cleaning tank, the power required and the frequency at which the system will operate. The frequency is especially important because an incorrect frequency selection may result in damage to delicate components or pitting of soft surfaces.
The cleaning tank should be sized with the largest dimension longer than the length of the largest part. Often a basket is used to contain small pieces and to keep instruments and tools from vibrating against the sides of the tank. In that case, tank must be larger to accommodate the basket.
The ultrasonic cleaning system must have enough power to fill the cleaning tank with ultrasonic waves. Too little power can result in dead spots in which cleaning may be incomplete. For especially large tanks, more than one transducer may be required.
The selection of the ultrasonic operating frequency impacts the intensity of the cleaning action. Low frequencies generate comparatively large bubbles and energetic cleaning action that can damage fragile parts. As the frequency increases, the bubbles decrease in size and the cleaning action becomes less intense. At the higher frequencies, even very soft and fragile parts can be cleaned effectively. An experienced manufacturer will be able to recommend what frequencies are best suited to the different medical cleaning applications
Kaijo Can Recommend and Supply Medical Ultrasonic Cleaners
Kaijo is a leading supplier of ultrasonic cleaning systems and components. The company works closely with customers supplying medical equipment and custom-designs ultrasonic cleaners to meet their unique needs. Kaijo offers free consultation and can follow up recommendations with deliveries from their complete line of ultrasonic cleaning equipment.