Ultrasonic surgical instrument cleaners work by sending high-frequency sound waves through a liquid that usually includes water and an enzymatic cleaner. These sound waves produce bubbles that implode in a process called cavitation. The implosion creates a high-energy scrubbing action that removes bioburden from the instruments.

Why is an enzymatic detergent essential in this process? The enzymes added to the cleaning solution break down proteins, fats, and carbohydrates that make up bioburden. By loosening this bioburden, the enzymes make it easier for cavitation to remove it, thus cleaning time may be reduced.

Use enzymatic solutions from the start

The addition of enzymes should begin at the point of use of the instruments, with the foams or gels used to keep bioburden from drying on the instrument. An enzymatic cleaner also should be used in the soaking and manual precleaning of the instrument prior to ultrasonic cleaning.

As part of the liquid in the ultrasonic basin, the enzymes can reach deep into cracks, crevices, hinges, and pulleys. They can infiltrate hard-to-reach areas, boosting the effectiveness of the cavitation and providing a more thorough cleaning than manual brushing alone.

Enzymes are proteins that act as catalysts, speeding up chemical reactions and reducing the amount of energy required for the reaction. In essence, enzymes attach to soil molecules and break them into smaller pieces. The enzymes snip off parts of the bioburden, digesting it and breaking it down.

They then move on to the next piece of bioburden, as the enzymes aren’t damaged by the catalyzed reaction. Ultrasonic cavitation lifts the broken-down soils and flushes the pieces down the drain. Enzymes are incredibly efficient, reducing the time each reaction takes and cleaning faster than detergents without enzymes.

Three types of enzymes used

There are three types of enzymes generally found in detergents used to clean medical instruments: proteases, lipases, and amylases. Each of these enzymes affects a different type of bioburden. Proteases attack proteins such as blood and tissue. Lipases break down fats and oils. Amylases attack starches, carbohydrates, and sugars, which is why they are often found in laundry detergents.

Different enzymes work best at different pH levels, so ultrasonic cleaner detergents generally contain enzymes that work best at a neutral pH. If the pH in the detergent and water solution becomes too high or too low, the enzymes will stop working, known as becoming denatured.

Acidic and alkaline detergents also can cause spotting, staining, and pitting of the surgical instruments, as well as damage to the interior of the ultrasonic cleaner. Neutral pH enzymatic cleaners can break down soils while not damaging the instruments or the machine.

Bioburden by itself can corrode medical instruments and cause pitting. Those pits can harbor biofilm, which can shield bacteria and viruses during sterilization and spread infection to the next patient. In addition to preventing pitting, enzymes can break down biofilm that forms in existing pits.

In addition to specific pH levels, each enzyme has an optimal temperature range at which it works best. Enzymes can become denatured at too high or low a temperature, making them unable to break up bioburden. It is important to use an enzymatic detergent recommended by the manufacturer of your ultrasonic cleaner.  That way, the enzymes won’t become denatured (and thus ineffective) during the cleaning process.