Highlighting water quality categories for medical device reprocessing

Last of a two-part series. Click here for part one.

By Jim Schneiter

AAMI and the FDA separate water used in medical device processing into two categories.

The first is called “Utility Water,” which is water that comes from the municipal water treatment facility. Utility water can be used for flushing, washing and rinsing devices during processing. The second category is defined as “Critical Water,” which is water that is extensively treated to ensure microorganisms, inorganic, and organic materials are removed. Critical water is used for the final rinse or for steam generation for the sterilization process. (11)

The following table lists the various categories of water and the recommended levels of water quality to be used in medical device processing.

Categories and Recommended Levels of Water Quality For Medical Device Processing

Note 1 - This is the quality of water that might come from the tap but might need some form of treatment to achieve these specifications.

Note 2 - If this is the final rinse prior to sterilization of a critical device.

Note 3 - If hardness is greater than 150 mg/L, a water softener is recommended unless used for washing and the cleaning chemistry is capable of handling higher levels of hardness.

Note 4 - For boiler-treated steam, most boilers are treated to maintain a pH of 7.5 or 8.5. Any treatment of water that goes into boilers should be in accordance with the sterilizer and boiler manufactures’ written IFU.

Note 5 - After high-level disinfection. (12)

The use of feed water or steam containing substances in excess of the stated values in the table above can contaminate reusable medical devices, reduce the service life of the sterilizer and may also void the manufacturer’s warranty. As a result there are specific tolerances relating to the quality of the sterilizer feed water as follows:

“Steam quality is a measurement of the amount of moisture in steam. For steam sterilization, there is typically greater than 95 percent steam and less than 5 percent moisture. Steam purity is a measure of the amount of contaminants in steam usually coming from the boiler. Impurities in the steam source may have an adverse effect on patients, equipment and the sterilizer itself. Various contaminants may find their way into the steam source. As well as being an obvious risk to patients, these reactive contaminants in the steam may have a damaging effect on the materials in the load, may cause corrosion and impair the longevity and functionality of the devices to be sterilized. Reactions may occur when contaminants come into contact with the surgical devices either directly or indirectly with materials that will come into contact with the sterilized product.” (13)

When assessing water quality, AAMI TIR34:2014/(R)2021 identifies four categories of water quality, which is determined by the medical device to be cleaned and by the disinfection or sterilization process used. Processing personnel and water maintenance personnel should collaborate with administrative personnel to implement the water quality initiatives:

Step 1: Assessment of water quality: The potable water from public utilities should be analyzed by water maintenance personnel to determine whether the water requires treatment and if so what kind of treatment.

Step 2: Implementation of water treatment process: Water maintenance personnel with device reprocessing personnel should ensure that water treatment provides the type of water quality needed for medical device reprocessing.

Step 3: Assurance of proper water quality: Water quality for the various stages in medical device reprocessing should be audited so that the proper water quality is used in each area.

Step 4: Ongoing monitoring of water quality: Where applicable, monitoring procedures should be established to ensure that the treated water is of adequate quality for reprocessing. (14)

Utility water can be used for pre-cleaning and cleaning of critical devices and for rinsing of semi-critical and non-critical devices. Critical water is required for critical medical devices and recommended for semi-critical devices as well. (15)

Regretfully, water softening systems have little control over water purity and downstream protection from chloride corrosion of the hospital washer and surgical instruments. AAMI TIR34:2014/(R)2021 states, “Softened water is water that receives limited treatment (softening) to remove inorganic material from the water. It will not reduce microbial levels, nor will it remove organic material from the water.” (16)

According to TIR34:2014/(R)2021, reverse osmosis has become widely used in medical device water purification systems. The advantage of reverse osmosis water is that it “filters out contaminants to a high of efficiency. Reverse osmosis removes particulate matter, organic molecules and pyrogens that deionized water cannot. It is less corrosive to steel and copper.” It is cheaper to run and maintain than deionized water systems. HTM2030 suggests that reverse osmosis would be the obvious choice as a core treatment technology, given its excellent impurity removal spectrum across ionic, organic and microbiological species. (17)

In order to solve this issue, some healthcare facilities have installed a central reverse osmosis water treatment system for various departments in the hospital that require deionized water. Other healthcare facilities have found a cost effective way to install point-of-use reverse osmosis water treatment units in the processing area.

The types, numbers and species of microorganisms in a water supply and in the water used in hospital cleaning supplies increases every time the cleaning products are re-used. To combat this problem, both AAMI and AORN recommend using de-mineralized water in the final cleaning step.

In addition to the water issues surrounding the majority of reusable medical devices, “There is special concern when ophthalmic instruments are reprocessed. Toxic anterior segment syndrome (TASS) is an acute inflammation of the anterior chamber of the eye following cataract surgery. It has been linked to irritants on the surfaces of intraocular surgical instruments, from detergent residues and from bacilli in water baths of ultrasonic cleaners. For example, potable or softened water in early processing steps may result in unacceptable endotoxin levels. In fact, AAMI recommends that high purity water be used for the final rinse when reprocessing medical devices that contact the blood stream, cerebral-spinal fluid or the anterior chamber of the eye.” (18)

Ensuring the quality of water used to process reusable medical devices is a key element in protecting patients from the dangers of a surgical infection caused by a device that remains contaminated after processing. Given this critical need to ensure patient safety, facilities should consider the use of professional consultants if they are not staffed and internally equipped to manage their water quality programs as per published standards. Maintaining water quality standards is an ongoing process requiring constant attention and monitoring by a dedicated resource to manage a facility’s water quality.

Given that water is used in all phases of device processing, every healthcare facility has the obligation to ensure the quality of the water they use for processing. In order to fulfill this critical obligation, every healthcare facility needs to determine how pure their water is and conduct regular checks to ensure the quality of the water to prevent patient harm.

About the author:

Prior to his retirement in December 2018, James Schneiter had been the founder, owner and president of?America’s MedSource Inc.,?which designed, developed, licensed and marketed a variety of implantable vascular devices, laparoscopic devices and neurosurgical instruments. Schneiter has nearly five decades of experience in medical device design and production and is a recognized expert in the area of instructions for use (IFU) and independent laboratory IFU validation studies. He also is a co-founder of #IFUcan. Schneiter can be reached at [email protected].

References:

11. “AAMI TIR34 – Water for the Reprocessing of Medical Devices” https://www.evoqua.com/en/articles/AAMI-TIR34-water-for-medical-devices/

12. www.aami.org

13. “Water for Instrument Processing” Marcia Frieze, Infection Control Today, April 29, 2009

14. AAMI TIR34:2014/(R)2021

15. Op. Cite.

16. Op. Cite.

17. Op. Cite.

18. “Water for Instrument Processing” Marcia Frieze, Infection Control Today, April 29, 2009