BOWIE-DICK TEST

WHAT IS A BOWIE-DICK TEST?

Brief on Bowie-Dick test:

Bowie-Dick (Air-Removal) tests assess the effectiveness of pre-vacuum sterilizers by verifying adequate air removal from the sterilizer chamber.
It might be wondering if Bowie-Dick tests are still necessary in sterilizers that feature programmed leak testing despite the fact that these air removal tests have been enhanced over time.
It must first comprehend why it is crucial to eliminate air from the sterilizer in order to completely appreciate why this test is still crucial today.
It’s common to refer to the air within a steam sterilizer as a non-condensable gas (NCG). Non-condensable gases, as the name suggests, do not condense when in contact with a colder object.
These gases serve as a barrier between the steam and the object, possibly protecting microorganisms and impeding effective sterilization.
Because non-condensable gas (NCG) could be hiding anyplace in the chamber, not even modern sterilizers are able to find it.
In order to detect the NCG, sensors must be positioned inside the packs precisely where it will either be trapped or gathered.
This is not feasible and demonstrates the continued importance of air-removal tests for autoclave testing with today’s advanced sterilizers.
Autoclave‘s vacuum leak test, which only assesses the integrity of the sealed pressure vessel and associated piping, confirms that air is not being sucked (Drawn) into the sterilizer during vacuum drawdowns.

Bowie Dick Test Standard Recommendation:
- It Should be as per The Association for the Advancement of Medical Instrumentation’s (AAMI) guidance ANSI/AAMI ST79 Comprehensive Guide to steam sterilization and sterility assurance in health care facilities.

When Bowie-Dick Tests are used or performed and its acceptance criteria?
- Bowie Dick test should be performed to qualify sterilizer performance when first installed, anytime it is moved, and following a major repair.
- This is qualification testing and needs three (3) successive test cycles with passing results.
- Bowie-Dick Tests are also utilised every day the sterilizer is in use, and normal monitoring only calls for one cycle of passing tests.
- Test process is the similar for both qualification and routine testing.

Step 1:
- Do a warm-up cycle.
- If this crucial step is skipped, the sterilizer won’t heat up properly, which could lead to falsely failing the Bowie-Dick Test.
- The most often stage to be skipped, it causes unneeded downtime.
Step 2:
- Place the Bowie-Dick Test Pack properly.
- It must be located on the bottom rack of the sterilizer, or sterilizer cart, straight over the chamber drain.
- Any remaining air in the chamber will inevitably move to the test pack since the vacuum is pulled from the drain.
Step 3:
- Confirm the chamber is empty (Vacant). Only the sterilizer cart (on medium and floor loader sterilizers) should be present for a correct test.
- If the cart is not included, the result could be superheated steam and a failed test.
Step 4:
- Run the test cycle.
- ANSI/AAMI ST79 does not deliver exact guidance on test cycle parameters.
- However, they specify that the programmed exposure time should be between 3.5 min. and 4 min.
- Follow the sterilizer and Bowie-Dick Test pack’s instructions.
Step 5:
- Open the test pack and understand results.

Check the sheet to determine if the color has moved from the center to the edges consistently and at the same intensity.
If the test is unsuccessful, one or more of the following factors may indicate that the sterilization system is ineffective:
Poor-quality steam produced by the sterilization machine.
Failure to make a vacuum with air being present.
A leak during air removal (initial vacuum phase).

Conclusion:

If the test is unsuccessful, the Bowie and Dick test is performed again; if this test is successful, a third confirmatory test is conducted; if this test is also successful, sterilization can start.
If the second test proved unsuccessful, the autoclave must be promptly pulled out of operation.
If your sterilization system is ineffective, further investigation will be needed to determine the cause and find a solution because the Bowie & Dick test does not provide information regarding failure causes.