Can An Ultrasonic Cleaner Impact Health Care?

Ultrasonic energy is a powerful tool in the healthcare field. Ultrasonic cleaners are employed in dental clinics, hospitals and in the manufacturing of surgical instruments, implants, prostheses, and orthopedic devices, among other areas, as the first step in removing contaminants that can spread pathogens endangering the health of caregivers and patients alike. Even in the home, a compact ultrasonic cleaner can be used to clean personal items such as scissors, nail trimmers, dentures, toothbrushes and other instruments.

The ultrasonic cleaning process is simple but the results are amazing. An ultrasonic cleaner is a tank filled with an ultrasonic cleaning solution, the composition of which is governed by what is being cleaned. Most of the solutions in wide use today are offered in concentrate form and are biodegradable for safe disposal. In the simplest case such as for home units water containing a surfactant can be used, perhaps augmented by a detergent or enzyme.

Fitted to the outside bottom of the tank are ultrasonic transducers that transfer energy created by an ultrasonic generator through the tank bottom and into the cleaning solution.

Objects to be cleaned such as surgical or dental instruments are placed in baskets that are suspended in the solution. When the ultrasonic cleaner is turned on, the energy creates billions of microscopic air bubbles that implode with violent force when they come in contact with items being cleaned. The process is called cavitation. It quickly and effectively removes contaminants from all surfaces of the instruments even from tiny cracks and crevices that cannot be reached by mechanical scrubbing without damaging the instruments. The cleaning process is often accomplished in less than 10 minutes. After being ultrasonically cleaned the instruments are rinsed, then following WHO recommendations, are disinfected and sterilized.

Ultrasonics and Sound

Ultrasonic cleaners such as units manufactured by Elma and available from Tovatech are designed to operate at ultrasonic frequencies that match the type of cleaning being done. For medical and surgical instrument cleaning, a frequency of 37 kHz (37,000 cycles per second) is typically employed. Lower frequencies such as 25 kHz are used for heavy duty parts cleaning, while higher frequencies such as 130 kHz create gentler cavitation less likely to affect highly polished and delicate parts. While these frequencies are above the range of hearing (for most people sound over 20 kHz or 20,000 cycles per second) the cavitation action on parts being cleaned and on tank walls can generate audible sound. If the noise is bothersome to personnel, it can be mitigated with ear protectors, by placing a cover on the tank and sound insulation around the tank.

Sound Practices

Healthcare equipment manufacturers and healthcare facilities employing ultrasonic cleaning should have in place standard operating procedures governing the maintenance of cleaners and solutions.

In the case of manufacturing surgical instruments, for example, solutions should be changed when they become visibly dirty or the cleaning process is prolonged. Tanks should be drained and carefully cleaned on a regular basis to remove residual contaminants that may fall to the bottom and potentially damage the tanks. Where cleaning cycles are ongoing, bath filters may be employed to help extend the life of the cleaning solution.
In hospitals and clinics using ultrasonic energy to clean medical instruments it is standard practice to change solutions on a daily basis to avoid passing biological contaminants to new batches being cleaned. In these cases filtration systems are not recommended to prolong the life of cleaning solutions.