The Principles of Medical Device Decontamination

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Detergents

Water is often described as the universal solvent and is an excellent medium for dissolving and dispersing many substances. Water is a polar molecule, which gives it some very unique properties. Much of what is unique about water is due to both polarity and hydrogen bonding. Water is not always the perfect solvent, and sometimes we need to modify or improve its properties; the most obvious example is the addition of detergents. Technically, detergents are known as surfactants (or surface active agents). They allow bonding between a polar solvent such as water, and a non-polar molecule such as a lipid (e.g. fats) helping to allow dissolution of hydrophobic molecules into the water. They can also allow wetting of the surface by lowering the surface tension of the water, this can allow the cleaning solution to ‘wet’ or penetrate microscopic areas of the medical devices to be cleaned. The soils typically found on devices that need to be cleaned may be organic, inorganic or both in nature. Organic soils may be comprised of muscle, skin, connective tissue, fat, grease, proteins (blood), carbohydrates, micro-organisms and other bodily fluids. Inorganic soils may consist of rust, scale (hard water deposits), residues from cleaners and residues from medical solutions (iodine, saline, skin preparations). Combination (organic and inorganic) soils may originate from substances such as bone.

A detergent should ensure instrument functionality. A detergent that can compromise the performance of an instrument is clearly not in the patients’ best interest.

Types of detergents

Enzymatic detergents are detergents that contain enzymes as well as surfactants. Enzymes are bio-organic molecules, in fact the majority of these enzymes, are actually proteins.

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