Wednesday, June 17, 2009

Maintain sterility in setting up procedure trays, and what is thermal equilibrium?

While some hospitals may totally utilize disposable diagnostic and treatment procedure trays, most hospitals still reprocess some procedure trays. The use of reprocessable procedure trays is certainly an acceptable practice, but just like anything else that we do relative to reprocessing and sterilization there are strict protocols, techniques and standards that must be adhered to. Assembly and packaging procedures must allow for proper sterilant contact. Products included in a set must be compatible with and able to withstand the sterilization process without any damage, degradation or reactivity. Commercially packaged and sterilized disposable products should never be resterilized (in their original packaging or removed) without the written approval and instructions of the manufacturer. Presterilized packaged supplies can be placed in a plastic bag and attached to the outside of the reprocessable procedure set. Blades should not he attached to reusable knife handles prior to sterilization for two reasons: (1.) The blade contact with the handle (metal to metal) may inhibit sterilant contact and (2.) The open exposed blade poses a safety hazard to healthcare workers. For emergency set ups the disposable blade in foil package may be placed inside the tray, adjacent to the reusable handle. While the foil package is not permeable to steam the outside will be sterilized. Some manufacturers of disposable knife handles with blades attached will provide documentation, which will permit the resterilization of the device in its original unopened package inside a hospital prepared set.

CS Question:

This might sound like a silly question, but why is it that channels in needles and other medical instruments are supposed to be moistened before sterilization in steam but not in other sterilization methods?

CS Answer:

First off there is no such thing as a silly question. The process of sterilization is a very important and critical function and preparing medical devices for the process requires detail and precise protocols. The preconditioning, cleaning, assembly, and packaging when done in accordance with appropriate procedures and standards will present the least degree of challenge to the sterilization process thus facilitating greater quality assurance. The channel or lumen is the hollow tunnel, which runs through medical devices such as needles, suction tubes, catheters and some surgical instruments. Steam is nothing more than vaporized water and is the sterilant in steam sterilization. To achieve adequate sterilization it is imperative that the sterilant have and maintain intimate contact with all areas to be sterilized, including lumens, for the required exposure time. Flushing lumens with water just prior to steam sterilization will moisten the lumens and as the temperature rises in the sterilizer the moisture in lumens will be vaporized turning into steam, thus ensuring that the sterilant reaches the internal portions of the medical device. Other methods of sterilization utilize chemical processes either in the liquid or gaseous form. Medical devices to be sterilized by these means must be dried prior to sterilization. Excessive moisture left on devices to be sterilized by liquid chemicals could dilute the chemical thus affecting it's germicidal efficacy. It is important that during liquid chemical sterilization the chemical fill and maintain total contact with lumens for the required sterilization time. Many chemicals are not compatible with others and when mixed there could be a reactive result creating another toxic chemical that could be damaging to a medical device or harmful to a patient. For example EO mixed with water results in the formation of ethylene glycol (antifreeze). Some sterilization processes, such as gas plasma, have restrictions on the depth and gauge of lumened devices that they can sterilize. It is imperative that you always obtain instructions for use, reprocessing and sterilization from medical device and sterilizer manufacturers. The sterilizer manufacturer should also provide you with validation documentation for specific device sterilization, as well as their FDA 510 k clearance.

Thermal equilibrium refers to the condition of having an equal balance of temperature through out a contained space or environment. For example in high temperature sterilization processes such as, steam or dry heat, organisms are destroyed by exposure to a specific temperature for a prescribed time period. The exposure or dwell time does not begin until the sterilization chamber and all it parts and contents have achieved the required sterilization temperature. Once this has occurred the condition is referred to as thermal equilibrium.

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