Decontamination
agitation can also help with the soil particles removal. Another important cleaning mechanism
involved in the decontamination of surgical instruments and medical devices is emulsification. This is the process by which oils and fats are dispersed in the form of very fine globules emulsified in a water based, alkaline solution. Emulsification is again promoted by detergents reducing the interfacial tension between the oil and water phases. Surfactants also stabilise the emulsion preventing its coagulation. Emulsified oils and fats are rinsed away. Solubilisation is the term used for the
process of converting a normally insoluble material to a soluble one. This is often achieved by the introduction of a detergent which can, via altering the pH of a solution, aid the solubilisation action by braking chemical or physical bonds in the contamination to build smaller parts.
Instrument manufacturer recommendations The mechanism of action and cleaning ability of alkaline detergents is well known and understood. However, although this is the case, many surgical instrument manufacturers still recommend that their products are decontaminated with a pH neutral detergent. The reason for this is that, although the alkaline cleaners are advantageous when considering their cleaning actions, they can also be corrosive to alkaline sensitive materials they act upon, especially if used regularly. This is a critical factor when decontaminating surgical instruments and medical devices whose functional integrity has to be perfect. Corrosion damage on surgical instruments can be identified during the visual inspection process and can include pitting, wear, friction, and stress-cracking among others. The initial stages of some of these types of corrosion may only be visible by using microscopy. Corrosion occurs because of the materials
Monitoring water quality is a key factor in the overall effectiveness and reliability of processing surgical instruments. The quality of the water being used in sterile services departments is a vital consideration for the protection of the patients in terms of safety and infection control.
surgical instruments are manufactured from. Most instruments are produced using stainless steel. A common misconception is that stainless steel means these items do not stain. This is not the case. Stainless means just that, the material ensures that the steel stains less than other non-stainless alternatives. Stainless steel is an alloy of iron (Fe) with a minimum content of 12% chromium (Cr) which produces a thin layer of chromium oxide known as the ‘passive layer’. The passive layer prevents corrosion by forming a protective cover on the surface of the steel which may be spontaneously or chemically induced. The chromium bonds with atmospheric oxygen forming oxide layer. The oxide layer is colourless and approximately 10 nm thick. It is this layer that provides protection to the steel from substances including alkali, acid, alcohol and water. The more chromium, the increased resistance to corrosion. The chemical corrosion of stainless steel e.g.,
Corrosion on a stainless steel surgical instrument
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chloride induced pitting, depends on several factors including humidity, temperature, time,
and pH. Preventing corrosion in stainless steel surgical instruments is problematic. Chlorides (e.g., from salt) are the enemy of the chromium oxide passive layer. This can be an issue when decontaminating surgical instruments as human blood contains many salts. Sodium chloride (NaCl) represents approximately 0.4% of total body weight making human blood comparable to sea water. Many types of stainless-steel alloys will suffer from pitting corrosion when exposed to environments rich in chlorides. In addition to saline solution used in theatres, blood contains chloride ions. Prolonged exposure to these ions can cause pitting and stress crack corrosion.
What makes the best detergent? What makes a good detergent, capable of removing microorganisms and stubborn residues from medical products without causing corrosion or damage to the item being cleaned? It takes years of experience to gain the understanding and knowledge required to formulate and innovate in the field of detergent chemistries.
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