EFHSS Questions and Answers - Question Q00127

Hi, I have a Vacudine sterilizer that i am beginning to set up and was hoping for some settings advice.
The settings that I have a starting point for are as follows
Temperature: 40 - 45 C
[EtO]: 370 - 450 mg / L
Pressure 2 - 2.5 atmospheres
what I am looking for is how long to leave it in for.

any help would be appreciated

Tim Yetman, Technical Service
MDMI Technologies Inc.
110-12051 Horseshoe Way
Richmond, B.C., Canada
V7A 4V4

(604)275-7944 x313

Dear,

Unlike moist heat sterilization, there is no mathematical model that will integrate the synergistic effects of the ETO cycle parameters. Therefore, after selecting the cycle temperature, humidity and gas concentration, a biological indicator or the product bioburden can be used to establish the exposure time (ref. Desinfection, Sterilization and preservation, S. Block).
To determine the exposure time one of the following methods (EN 550: Validation and routine control of ethylene oxide sterilization - CEN page) can be used:

• Method A: Survivorcurve construction
• Method B: Fraction-negative method
• Method C: Half-cycle method.

I can also recommand the lecture of 2 articles in "Central Service" (see publications page, periodicals for the abstracts)

• 5/01: Validation of sterilization processes with ethylene oxide, S. Huckner.
• 1/02: Ethylene oxide sterilization of surgical sutures monitored with bacillus subtilis, A. Ferraz.

The answer of Pete Bobb on question Q00122 gives also useful information.

Good luck,
Wim Renders