REUSABLE MEDICAL DEVICES
of pump pressure. The detergent may not be the only contributor to foaming, of course; dissolved sodium ions in the water supply may also cause excessive foaming, as can the presence of proteins, which may be present on the load (much soiling occurring on reusable medical devices consists of blood and other high-protein soils).
Detergent formulations
The detergents used in medical device decontamination contain one or more surfactants to provide the detergency necessary for suspending various soils; detergents are typically complex formulations of a wide range of chemicals in order to achieve the desired cleaning properties and detergent shelf life. Additionally, detergents contain other chemicals that significantly enhance their performance. These other chemicals typically give the detergent formulation their classification name - enzymatic, alkaline and neutral.
These detergents should aid in the removal of adherent infectious agents and the organic matter that protects them, thus ensuring a better contact between the disinfectant/sterilant and any remaining infectious agents in subsequent stages of the decontamination process. Formulating a detergent that is inherently low-foaming is of course desirable, but also making sure that if foaming does occur due to high sodium ions or high protein soiling of the
In order to allow a greater spectrum of detergent efficacy in a range of waterquality supplies, certain chemicals can be added to addresses these negative effects of hard water and metal ions. These chemicals are typically known as sequestrants.
load, the detergent is able to dramatically defoam the washing solution.
Types of high performance detergents
Enzymatic detergents are detergents that contain enzymes as well as surfactants. Enzymes are bio-organic molecules; the vast majority of these enzymes are actually proteins. The enzymes are designed to break down larger molecules into smaller, more water-soluble ones, a process known as hydrolysis, and are extremely efficient biocatalysts. The active site is in the shape of a 3D cleft or pocket, containing the catalytic/binding site; this site promotes the formation and degradation of specific bonds. These enzymes are very selective and only target specific soil components and will have negligible effects on other molecules. The detergent formulation is typically neutral to mild alkaline pH in order to prevent damage
to these enzyme proteins. These enzymatic detergents generally work better in immersion systems used for manual cleaning, but are also widely used in automated washer-disinfectors. Enzymes are typically named after the substances they help to break down; for example, proteases help to break down protein, amylases help to break down starch, lipases help to break down fats/lipids and cellulases help to break down cellulose; typically, however, only proteases are useful in medical device cleaning formulations due to protein being of particular interest as a model soil. Different proteases can be combined to broaden pH or temperature effectiveness, but using a higher concentration of the same enzyme will not necessarily increase efficacy; enzymes are only one part of the process of breaking down soils, and other elements are still required to wash and remove all types of soil.
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