WFHSS Questions and Answers - Question Q02338

AAMI ST79, paragraph 8.8.1 recommends at least a 30 minute period to cool the load and states it could be up to 2 hours. It also states not to touch the items because of possible contamination. Without a doubt, the items have sterile, heated vapor inside the non woven wrap or containment device.
Can anyone offer some science behind either of these two recommendations. Is it a needed requirement or a sacred cow?

1. Does anyone simply standardize on a 30 minute cool time before removing all items?
2. What is your average cool down time?
3. Does anyone actually measure weight gain, before and after to set a cool down time requirement? How about a specific cool down temperature (like 72 deg. F).
4. Does anyone think or have documentation that there is the potential for contamination by touching the non woven barrier material? Obviously, metal or plastic containers (i.e. Aesculap/Sterion) would not have potential for contamination if touched.
5. Do you leave the load inside the chamber with the door cracked for a timed period or remove the load immediately after cycle complete to start the cooling process?

Chip Moore
Rochester, NY

Hi Chip,

I can only reply in general terms to your concerns.
We would routinely use a 30 minute cool time, however some heavy items (ortho) set may take longer.
The governing standard in Australia and New Zealand is AS/NZS 4187 and in Section 6 it states:

6.1 STEAM STERILIZERS
6.1.1 With drying stage
On completion of the drying stage, the load shall immediately be removed from the sterilizer and a visual inspection made to ascertain that the load is dry, and that sterilizing indicators have made the required colour change. Directly after the sterilizing process, items are very vulnerable to contamination by moisture or improper handling. The procedures below shall therefore be followed:

1. On removal of the load, the operator shall check recording charts or print-outs and sign the designated record sheets to indicate that the required parameters have been met, or notify the supervisor if deviation of any parameter is detected.
2. Loading cars with cooling items shall be kept away from high activity areas.
3. Forced cooling of items by fans or boosted air conditioning shall not be used.
4. Cooling items shall not be placed on solid surfaces, as condensation from vapour (still within the pack) may result.
5. Items that have been dropped on the floor, placed on a dirty surface, compressed, torn, have broken seals, or are wet, shall be considered non-sterile and shall be reprocessed.
6. Where a steam sterilizer with a drying stage has been used to sterilize an unwrapped load, appropriate handling procedures for unloading shall be developed and documented by the health care facility.
7. Where plastic dust covers are employed, the item shall be cooled before being placed in the dust cover (see Clause 9.3 (b)).
8. If dust covers are used for the purpose of storage, they shall be labelled ‘Dust cover only’.

I hope this is useful.
Cheers
Ray

When the cycle is opened the cart is remover immediately we would never leave the door open slightly as our machines don't allow this. The reason you don't touch the items is to do with contaminatingthe items with your hands. If you handle the items too soon you transfare bacteria from your hands onto the pack & this multiplies as we know bacteria love heat. Then theatre staff handle it & so on.

Chip,
We use 25 minute dry period in the autoclave, then "crack" the autoclave door and wait another 1/2 hour before removing the load.

Several years back we had no warm up time and, i believe, a 15 minute dry time. This resulted in wet packs consisting of 3 metal single basins with 3 emesis basins (separated be small towels) and two solution basins (medium size). We long ago converted to pre-assembled sterilixed single basins and have had no need to process the emesis basins and solution basins as they are no longer used.

After our current loads are removed from the autoclave, they sit for approximately 1 hour, some loads cooling a little sooner than others depending what is on the load.

Touching the kimguard with the fingers to test how warm an item might be may not be the wisest move as oils from your fingers may transfer through the wrap. Kimguard reps may tell you more specifically what might happen.

However, for as much as we wash our hands and as dry as they become from handling stock, linen wrap, kimguard and other moisture sucking products in central, its a wonder there could be any oil on your hands at all.

The problem comes back to your main question as to who has any
quantitative data to support either position. I'm sure techs touch items every day to see if they are cool enough to put on the shelf but have any of us caused infections that we are unaware of?

Hi Chip,

Cooling time varies with the weight / mass of the load.
Heavy Orthopedic trays take much longer to cool than light Ophthalmology instrument sets.
I train staff to begin by touching the cart frame with the inside of their wrists, somewhat like testing the heat of a baby's bottle.
IF the cart itself is cool, touch the edge of a heavy rigid container with the inside of your wrist.
IF the rigid container is cool, then you can unload the cart.
Touching the metal of the rigid containers will not contaminate the contents of the tray like touching 'wrapped' items can.
The water vapor in warm wrappers can act as a conduit for microbes to 'swim' through the wrappers.

Warm Regards,
Pete Bobb

Thanks to all for your responses. I thought the NZ/Aussie standard outlined logical steps w/o reference to the "touching" issue. Let's assume for a moment that "touching" a cooling tray wrapped with non woven material could lead to load contamination. Conversely, when does the barrier protection of non woven wrap begin? Does the barrier protection begin at a certain cooled temperature and if so, what is that temperature? I agree with Barry, techs touch packs every day. If so, then using non woven wrap material could leads to contaminated items.
Where is the science? Either non woven wrap is a good barrier protection material or its not and, in my opinion, that includes during the cool down time. Using linen/textiles material and wraps could have wicking issues during the cool down period.
Again, thanks for your input. Finally, I still looking for the science behind avoiding touching items during the cool down period?
Chip

Dear Chip,

Dear
I am quoting from Dr. Dominique Goullett lecture at our annual congress,2009:
"We are obliged to blindly continue to apply to certain dogmas"... "There is still much to learn about sterilization".
Not every recommendation is valid and scientifically evidence based. Some of the recommendations we follow result from decision taken by standard committees and are based on best judgment of knowledgeable people. So, you will not find a scientific evidence for every recommendation. It would be a challenge to designed research on this issue, since a lot of variables will have to considered in order to validate the research.

Regards
Yaffa Raz

Hi Chip,

The 'wicking' of microbes through wrappers is not directly a function of temperature, but of moisture in the wrapper.
A hot tray wrapper frequently still contains high levels of water vapor which keeps the wrapper moist.
Hands are never sterile, no matter how often we wash our hands and how much alcohol we put on our hands.
That is why surgical staff wear sterile gloves even after washing their hands.
Handling a moist wrapper with bare hands creates conditions which allow microbes on our hands to get on the wrappers and 'swim' through the moist wrapper.
The pressure exerted on the tray from our hands helps 'squeeze' the microbes through the wet wrapper.
Dust carrying microbes falling on the wrapper is not squeezed through the wrapper with physical force like the microbes from our hands is squeezed through the wrappers.

And, to the bigger problem - Why would anyone need to handle the hot trays except to put the tray on a cool surface which encourages the condensation of the water vapor, creating puddles inside your trays, or creating wet packs?

Warm Regards,
Pete Bobb