Instrument air and Ao validation

July 22, 2022

Q

 “We have a co-worker who uses a can of Air Duster from Best Buy. Could that be used instead of the air gun provided at our tables? If there is an ST79 or AAMI recommendation we can read about, or something you can send, it would be appreciated. Also, the department doesn’t have any type of air hook up on the clean side.”

A

 In the latest update of ANSI /AAMI ST79, they defined the type of air that a medical device reprocessing department should have available within their department. The term they use is “instrument air”. The definition of instrument air is, “Medical gas that falls under the general requirements for medical gases as defined by NFPA 99 (Health care facilities code), is not respired, is compliant with the ANSI/ISA 7.0.01 (Quality standard for instrument air), and is filtered to 0.01 microns, free of liquids and hydrocarbon vapors, and dry to a dew point of −40° F (−40° C).”We know that air is needed in every medical device reprocessing department. It is needed in the decontamination area to “flush/blow out” debris and in the assembly area to help dry lumened devices and sets that still might be wet. Items should be dried for steam as well as low-temperature sterilization methods, unless otherwise directed by the sterilizer manufacturer or the device’s manufacturer. That is why ANSI/AAMI ST79 defined the correct type/kind of air that should be available, unless the manufacturer of said medical devices gives you other specific directions.

Many sections within ANSI/AAMI ST79 reference instrument area, such as a) 3.3.1, b) 3.3.6.1.1, and c) 7.6.4.2. These sections provide support for having the correct type of instrument air available for your department. Portable instrument air tanks can be brought in for staff to have the proper equipment to provide a clean and functional medical device so that it can either be high-level disinfected (HDL) or sterilized.

I also want to make sure that you have a way to monitor the pressure that is being used. In my view, just hooking up air with no monitoring is wrong. Some medical devices require specific pressure requirements, and, as a medical device professional, you need to ensure you are processing that medical device the proper way—including air pressure.

Lastly, I see many people flushing devices on the assembly side. In my view, they should be wearing at least some type of safety glasses to help prevent any possible eye injury if “stuff” is blown out accidentally.

My response to your question about whether to use a can of spray air to clean any medical device is, “No.” Unless the manufacturer’s instructions for use (IFUs) specifically states to do so, which up to now, I have not seen any air cans in the IFUs, I would not recommend it.

Q

 “I am buying a washer and the salesperson told me the washer is validated for Ao. Is this important and what does it mean?”

A

 As we all know, automatic washers are sold all over the world, and companies have to meet various market specific requirements.

A washer sold in the United States can also be sold in Europe. The basic model might be the same, but features might differ from market to market, so it can be sold there.

 A° is an expression of the time/temperature needed for the disinfection process to achieve a desired level of kill. Specifically, A° is the time required to achieve a specified log reduction of microorganisms based on the water temperature of the thermal disinfection cycle. The A° concept is used mainly outside the United States and is described by ISO 15883-1.

The FDA at this time does not recognize A° but does stipulate that any washer/disinfector sold in the United States claiming thermal disinfection for reusable medical devices needs to validate that it can achieve the stated level of disinfection.

While it is a nice to know, A° is not germane to washer-disinfectors marketed in the United States. It is not part of the requirements process as outlined in various FDA documents, such as:

• Medical Washers and Medical Washer-Disinfectors - Class II Special Controls Guidance Document for the Medical Device Industry and FDA Review Staff1

• Guidance Document for Washers and Washer-Disinfectors Intended for Processing Reusable Medical Devices.2

You have raised a very good question concerning “what I need to know” when buying a washer disinfector.

You could also ask the manufacturer for the validation study (sometimes called a white paper), which should explain how the equipment was tested and the results. Another important standard you can ask about—was the equipment tested according to ASTM D7225 Standard Guide for Blood Cleaning efficiency of Detergents and Washer-Disinfectors. Because you do want to make sure it can actually clean blood off at least stainless steel (the most common material used to make surgical instruments).3

References:

1. Center for Devices and Radiological Health & Food and Drug Administration. (February 7, 2002). Medical Washers and Medical Washer-Disinfectors - Class II Special Controls Guidance Document for the Medical Device Industry and FDA Review Staff. Content current as of July 17, 2018. https://www.fda.gov/medical-devices/guidance-documents-medical-devices-and-radiation-emitting-products/medical-washers-and-medical-washer-disinfectors-class-ii-special-controls-guidance-document-medical (or https://is.gd/txvkOX).

2. Center for Devices and Radiological Health & Food and Drug Administration. (June 2, 1998). Guidance Document for Washers and Washer-Disinfectors Intended for Processing Reusable Medical Devices. Content current as of February 12, 2018. https://www.fda.gov/medical-devices/guidance-documents-medical-devices-and-radiation-emitting-products/medical-washers-and-medical-washer-disinfectors-class-ii-special-controls-guidance-document-medical (or https://is.gd/4fO1a6).

3. Basile, R. (August 2006). ASTM publishes new guidelines ASTM 7225. Managing Infection Control, August 2006, 50–52.

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