Wet Packs (wet trays)

[Colleen]

Question.... Is there a documated process for wet packs?

[Biff]

Question.... Is there a documated process for wet packs?

I believe I saw a "recall" process on the sterileprocessing.org downloads page. It may have been in the document for standards or QA. If you can't find it or they no longer have it posted, let me know I can fax it to you. :)

[chipmoore]

I have posted text from material we furnish to our service rep's when addressing "Wet Packs". It is long but I think you will find the material interesting. Most wet packs are the result of the steam supply. Have your facility engineer walk the steam line from the boiler to your sterilizers and insure all traps are functioning. Next is proper traps and drip legs at the sterilizer connection. Proper boiler maintenance is critical, especially when the facitilty switches from Summer demand to Winter and the opposite during Spring months. Finally, one of my pet peeves is the term "wet packs". What does it mean? Visible moisture outside or inside? Wrapped trays? Plastic containers? Basin sets? Each one could point you towards a root cause solution.
Chip Moore
Getinge
Rochester, NY

Solving a customer's wet-pack problem can be time consuming and frustrating to everyone. Listed below are some things you should do when trying to implement corrective action.

1. Approximately 50% of wet-pack problems relate to the steam supply.
 Verify there is at least 97%, saturated steam. If steam quality cannot be verified with instrumentation, try this:
 Weigh a linen pack on a gram scale prior to processing (in an empty chamber) at normal prevac settings
 Use only 30 seconds for dry time
 Weigh the pack and figure the difference
 The weight gain will give a close indication of the amount of moisture content (%) of the steam. (Normal expected weight gain is about 2%.)
 You could also try covering and taping Kimberly Clark non-woven wrap to the load car shelves and run empty chamber, prevac cycles (with and without dry time). This can also point towards areas of potential trouble (water beads).
 Steam quality can be improved by use of filters and separators. Insulating steam pipes, adding drip legs and assuring correct pipe size will also help. Long steam runs, and end-of-line connections can contribute to poor steam quality. So can boiler maintenance and chemical treatments.
 Poor or improperly maintained condensation return systems can contribute to wet loads.
 Verify that the dynamic steam pressure is within the specified range and is properly trapped. Low steam pressure contributes to wet packs.
 The PRV should be as close to the sterilizer steam inlet as possible. The more distance between them, the more condensate builds-up.
 The steam flow rate to the chamber can contribute to wet loads. Slowing it down by installing an orifice at the chamber inlet, can help.
 Vacuum depths during the dry phase should be in the range of 0.4 psia to 0.7 psia. General dry time recommendations at these vacuum levels should be 20 minutes.
 Seasonal changes in heating or cooling in the building can contribute to wet packs.

2. Approximately 35% of wet pack troubles relate to Loading Techniques
 During the sterilization process, condensation is created. Drainage, or the ability to drain condensate is crucial.
 Load heavy, metal items on the lower shelves.
 Steam must have the ability to make contact with the load, over-loading inhibits steam contact.
 Loads must not be touching the chamber walls, ceiling or baffles
 Internal load wicking and absorbing condensate helps, especially with nested metal bowls/basins. Putting towels on shelves can help absorb moisture.
 Paper/plastic pouches need to be vertical. Never have plastic/paper pouches inside other containers.
 Plastic containers are difficult to dry, especially large orthopedic containers with multiple layers.
 It’s good practice to let the load sit on the load car for 30 minutes or more to allow the load to cool, and the heated steam vapor to dissipate. Opening an instrument tray or basin set immediately after the cycle may create an apparent problem that would not have been visible if the load had been allowed to cool. Keep the load away from air conditioning vents during the cooling process.
This would be the location of the loaded cart in relation to the overhead air conditioning ducts. This is as critical before processing the load as it is after processing. If the load sits under a vent before the load is processed, the metal mass is cooled well below "ambient" temp. When the load is processed, the load produces a greater amount of condensate due to the temperature difference and could create a wet pack condition same as sitting a just completed load beneath a vent and allowing it to cool too rapidly. Also an air conditioning vent located in the service area of the sterilizer could also cause wet packs if the vents are directed at the unit. This will cool the incoming steam and condense it in the line.
 Use of heavy duty nonwoven wrap may require extended dry time.
 Some rigid containers have little or no drainage.
 Customers may be using the wrong filters in rigid containers.
 Usually, a 20-30 minute dry-time at specified vacuum levels, is sufficient. An additional "bake-time" after the cycle is complete (door in the unsealed/cracked) is better than adding more dry time. Adding more dry time (i.e. 40-45 minutes total dry time under vacuum) is not as effective as the radiant heat from the jacket walls during the “bake” time. It will also reduce water usage.

3. Approximately 15% is Mechanical/Design
 Verify that the correct steam baffle is installed correctly.
 Door Gasket leaks.
 Steam to chamber valve may be leaking (wisping) steam under the vacuum, but not enough to fail the leak test.
 Steam to chamber leaks of any kind can influence drying. Scrutinize chamber and piping for tightness. Monitor leak test and get as small of leak as possible.
 Internal heat exchanger leaks.
 Drain check valve leaks. Water in exhaust piping adds moisture to chamber and may not show up in leak test.
 Unbaffled top chamber orifices such as air-in ports and pressure transducer ports may be dripping onto loads.
 Cart rails may be collecting puddles/droplets of water and adding to moisture in chamber during drying phase (water may be flashing off prior to end of dry time and has been absorbed into load).
 Improperly leveled sterilizer may also be pooling water, which is adding moisture in the chamber, but also flashing off early and adding moisture to the load.
 Rusted/dirty chambers/doors can be a source of condensate and should be cleaned.