Hi! I am looking for a method of detecting the presence of ethylene oxide, inside or comes out of the ETO sterilizer chamber, while opening the door. The manufacturers speak, their machine is incoperated with latest safety measures and no chance of inhalation of ETO or left behind as residue with the pack. But being central service professionals, how should we confirm the safety of our staff as well as our patients? Kindly help if any one of my colleagues succeeded in this thought process.

Regards,
Murali

Dear Muralikrishnan

There are two main types of sampling methods for the determination of TWA (time-weighted average) concentration of ETO.

• Active sampling, a method where an air moving device (usually a pump) draws a known volume of air through an ETO-collection tube, e.g., a solid adsorbent tube; and
• Passive (diffusive) sampling, a method where atmosphere is sampled by molecular diffusion, with ETO being adsorbed by a solid adsorbent within the sampler, which is usually a tube or a badge.

There are a variety of gas detection devices available. The ideal monitor should be sensitive to concentration of ETO below 1 ppm, reliable, easy to use and inexpensive.
Chemical ananysis should be made by a recognized laboratory. Some manufactures/suppliers of tubes and badges also provide analytical service. Worldwide providers (you can select your country) are e.g. 3M Safety - 3M Personal Air Monitroring Systems, see www.3m.com and Draeger Safety: www.draeger.com/ST/internet/CS/en/OurMarkets/our_products/our_products.jsp
I hope this is of some help.

Kind regards
Josy Holdener

Dear,

From my personal point of vue and experience I advice you strongly to continuously monitor the Ethylene Oxide concentrations in the working environment in order to protect your staff. Although the EO sterilizer can be equipped with the latest features problems with too high EO concentrations can always occur.
In the CSSD of the hospital I work in they were e.g. due to:

• the drain pipe (EO exhaust) that came loose. This happened several times, once after maintenance.
• worn-out joints in the EO exhaust.

To monitor EO we use to our satisfaction the Polytron 2 of Drager. This is a measuring head with elctrochemical sensors. Sensitivity and selectivity of this method are limited but so is the price and it provides us with the data we need (Gaz chromatography is extremely expensive).

It is also very important in order to limit contact with EO, as much as possible, to allow aeration of the load in the sterilizer.

For information on the protection of the patient I refer you to questions Q00079, Q00140, Q00145, and Q00152.

Best regards,
Wim Renders

Murali

Certain safety features can help avoid accidential exposure to EO.

All exhaust piping and EtO feed pipes should be welded stainless steel.

Have your operators wear badges, available from AMSCO. After wearing the badge it can be developed and read to get an indication of the person'e exposure to EtO.

Proper cycle engineering - Make sure that a sufficient number of evacuations and nitrogen (or air) flushes is performed. Also, program the sterilizer back vent (or rear exhaust blower) to come on for a certian amount of time before the door is opened. Make sure the sterilizer back vent stays on during unloading of the sterilizer, and for another half hour (or more) after unloading.

If you send me an email I can reply with a spreadsheet that shows all the volumetric calculations I perform before approving a cycle design.

Hope this helps,

Paul