EFHSS Questions and Answers - Question Q00554

After we wrap instruments for the OR. We put them into the steam sterilizer. At different times some of the items come out wet. There are drops of water on one or two of the items. We have the time set for 4min prevac and 30 min dry. It is not dependent on the size of the load. There are two shelves in the sterilizer usually it is on the bottom that the instruments are wet. How long are we to leave them in the sterilizer, prior to removing them? Thank you

Susan Dowd

Susan

There are so many reasons why loads are delivered in a wet condition that solutions are often individual to the circumstances in each case. However, the symptoms you detail suggest that condensate (ie water) is dripping from shelves and load items above and ending up on the loads below. This migration of condensate is difficult in that the water needs to regain some of its delivered energy in order to be flashed off into steam during the drying stage. If too much water collects at a lower position then there will not be sufficient energy for this to occur - hence wet loads.

The solution is not in the length of drying alone but more in removing the cause of the problem - movement of water. Ideally the condensate produced as a necessary by-product of sterilization should either stay where it is formed inorder to regain the required energy during drying (use tray liners, abosrbent material etc) or be diverted into the drain away from other load items (diverting shelf trays etc). It is also possible that the upper shelves and carriage construction may cause water to drip. The best solution lies in diverting any dripping water from lower shelves with sloped trays under the shelves. Your sterilizer manufacturer should be able to help.

Best wishes
Peter Hooper

Susan

With no contradiction to Peters explanation, I want to add:

1. The steam quality (wet steam, dry saturated or superheated) has a significant influence on steam consumption and drying properties. Meaning: you must supply much more wet steam, rather than dry saturated steam to increase the temperature of the goods to be sterilized. This huge amount must be displaced on the drying stage. Condense (water) needs time (long time) to change from liquid to vapor!
2. Pay attention to method of loading. Do your best efforts to prevent accumolation of condense (water).
3. If the BD Test proves that 4 min. pre-vac is enough, you can assume that you have a good pump (good vacuum). So, the vacuum is not the problem of lack of drying.
4. Usually, 15 to 20 min. (from end of exposure period) of drying should be enough.
5. Control of dryness shall be done after exposing and equilibrating to ambiant conditions.

miki

I think this can be avoided with careful loading of the loads,and bringing the same to equilibrium gradually after sterilization.Thus loads should be in the sterilizer for 15-20 minutes after sterilization with doors cracked open about an inch.Loads contained in metal on the bottom rack and wrapped items and peel pouches on top racks brings out the best results.

Miki & Peter have good suggestions above.

Deviah.

Deviah

Practically, leaving the load 10-20 minutes in the chamber with partly door open, is what many are doing, but, more that it is wrong, it means bad performance (wet steam, poor vacuum, longer cycle, etc.)
Good practice means to attack the source of the problem rather than the result.
Sterilization is an interaction of goods-packaging-autoclave-user. Each is important.
Do you realize the connections?

and have agreat day
miki

I have found that if you hold your pre-vac put do not hold on the upside (pressure level) this can create condensate. Try setting your parameters to hold 4 min on your pre-vac and 4 min on your pressure level. KIM

Susan,

You state that the wet loads are at different times of the day. Is the boiler that supplies the steam a multi use boiler? If yes, then you need to monitor the time slots of your wet loads coincides with multi use of the steam supply to ascertain whether the steam offtake is being utilised by other users at critical times, which would create a recovery time frame for the boiler (depending on its capacity and efficiency rating)
Peter's comments are very valid, but if the problem is occuring on the bottom shelf only, then there could be to much metal on the steriliser cart. The best way to resolve this issue is to drape the load on the bottom shelf with an absorbant drape until, as Peter suggests, the steriliser maintainance person gives you assistance in resolving your problem, which could well be an excess of metal on the cart in the chamber. The vacuums that are excercised in the conditioning phase really have no bearing on the outcome of the physical aspects in regard to wet packs. They are purely to effect air removal and steam penetrtation.If you have wet steam, then this can be seen in the chart print out during culmination of the pre-heat phase of your cycle.
If you have to much metal concentrated in one spot or area in a tray, then, as Peter has stressed, the energy required to flash off this condensate is not available and you will finish up with wet loads. Use a tray liner to take up this excess condensate, which might also help to dry the load.
Trust this info from left field helps,

Kind regards
Bill Davis
gke Australia.