Manufacturers of surgical instruments recommend the use of neutral pH enzyme detergent cleaners. Neutral pH enzyme surgical instrument cleaner detergent concentrates optimize the efficacy of the passive oxide layer.
This will provide a longer life for stainless steel surgery instruments. Cleaning concentrates with a high or low pH have been shown to erode the passive layer. The most common of these cleaning concentrates utilize an alkaline detergent with an acid neutralizer. Your first-line-of-defense against Preventing Corrosion is the passive oxide layer of your Surgical Instruments. Stainless steel surgery instruments are made of corrosion resistant high-grade specialty steels. One of the special characteristics of these steels is that the manufacturer forms a passive oxide layer on the surface, which protects them against corrosion. It is imperative that you maintain the passive oxide layer to prevent corrosion and maintain your surgery instruments in optimal condition. If this is not done the stainless steel will be more susceptible to corrosion, pitting and stains.This will reduce the life of the surgery instruments. Initially, all stainless steel surgical instruments have the same corrosion resistance.
The use of Surgical Instrument Cleaners that deliver an acid rinse will release nickel from the stainless steel and decrease the efficacy of the passive layer. This is most critical on initial reprocessing events of stainless steel surgical instruments.
What is a Stainless Steel Surgical Instrument?
Stainless steel is essentially a low carbon steel which contains chromium at 10% or more by weight. It is this addition of chromium that gives the steel its unique stainless, corrosion resisting properties. The chromium content of the steel allows the formation of a rough, adherent, invisible, corrosion-resisting chromium oxide film on the steel surface. If damaged mechanically or chemically, this film is self-healing, providing that oxygen, even in very small amounts, is present. The corrosion resistance and other useful properties of the steel are enhanced by increased chromium content and the addition of other elements such as molybdenum, nickel and nitrogen. Stainless steel has a passive film created by the presence of chromium (and often other alloying elements, nickel, molybdenum) that resists this process. When exposed in air, stainless steels passivate naturally (due to the presence of chromium).
How is the passive oxide layer Manufactured and Maintained
The passive layer or stainless steel is intended to prevent or resist corrosion. The process is called Passivation. Passivation and Polishing eliminate the carbon molecules form the instrument surface. This forms a layer which acts as a corrosive resistant seal. Passivation is a chemical process that removes carbon molecules from the surface of the instrument. This chemical process can also occur through repeated exposure to oxidizing agents in chemicals, soaps, and the atmosphere. Polishing, by the manufacturer, is a process used to achieve a smooth surface on the instrument. Surgical Instruments are polished because the passivation process leaves microscopic pits where the carbon molecules were removed. Polishing also builds a layer of chromium oxide on the surface of the surgery instrument. Proper cleaning, handling, and sterilization will build up the layer of chromium oxide and protect the Surgical Instrument from corrosion and /or pitting. In some circumstances older instruments have higher resistance to corrosion than new ones. The newer instruments have not had the time to build up the chromium oxide layer. Improper cleaning and sterilization can cause the layer of chromium oxide to disappear or become damaged thus increasing the possibility of corrosion and/or pitting. Proper cleaning and sterilization can cause the layer of chromium oxide to improve over time thus decreasing the possibility of corrosion and/or pitting.