Helix test for autoclaves

The helix test - also known as the steam penetration test - is an essential part of the routine control of class B autoclaves used for the sterilization of medical instruments and materials.

The helix test is used to check that a sterilization process with fractionated pre-vacuum is running correctly. The test system consists of a test body (PCD = Process Challenge Device) and an indicator strip. The helix belongs to the group of class 2 chemical indicators in accordance with DIN EN ISO 11140-1.

In accordance with DIN EN 13060, the test specimen is used to simulate loads with complex hollow bodies (classification type A) for small steam sterilizers and can also be used as a routine test for large sterilizers in accordance with DIN EN 285. A successfully performed helix test thus ensures that the autoclave achieves the necessary pressures, times and temperatures to effectively sterilize even hard-to-reach areas of hollow instruments.

The helix test should be carried out regularly as part of the routine checks of an autoclave to ensure that the device is functioning properly. A batch-related test of the autoclave is mandatory in the following situations:

1. After the installation of a new autoclave or after extensive service and maintenance work.

2. For each sterilization cycle that includes complex hollow instruments of category "Critical B" to ensure that the autoclave also reliably sterilizes the cavities of these instruments.

Regularly performing the helix test simplifies the workflow and increases safety. This means that the daily steam penetration test with MELAcontrol or MELAcontrol PRO can be dispensed with, as the helix test ensures adequate verification of steam penetration.

The helix test is usually carried out with a special test device, the so-called helix test body. The following steps must be observed:

1. Preparation: First remove an indicator strip from the foil pouch and fold it in the middle so that the writing and the indicator area are facing inwards. Insert the folded indicator strip with the folded edge first into the sealing cap of the helix test body and screw the cap firmly onto the test body.

2. Loading: The Helix test specimen with the indicator strip inserted is then placed on a tray in the autoclave. Pay attention to any instructions in the validation report.

3. Running the sterilization program: Now start a class B sterilization cycle. During the vacuum phase, air is removed from the tube of the test specimen so that the steam can penetrate to the indicator strip at the end of the system.

4. Evaluation: At the end of the cycle, check the indicator strip. A complete color change indicates that the steam has reached all parts of the test specimen. An incomplete color change, on the other hand, indicates faulty steam penetration, which could indicate leaks in the steam system or the presence of non-condensable gases (NKG).

5. Documentation: Finally, the results should be recorded in the release and quality control records. The indicator strip does not need to be stored as recoloration may occur over time.

Different types of helix test specimens are available for different requirements. The MELAcontrol system includes both the reusable MELAcontrol Pro permanent test specimen and the MELAcontrol Helix test specimen, which is designed for up to 250 cycles. Both offer an efficient and cost-effective solution for routine operation.

After 250 cycles, the MELAcontrol Helix test specimen must be disposed of. When purchasing a new one, 250 new indicator strips are supplied so that you are immediately ready for use again. For practices with higher sterilization requirements, we recommend the MELAcontrol Pro. This permanent test device remains in the practice and only the indicator strips need to be purchased and the seal in the lid replaced.

The Helix test is an indispensable tool for ensuring sterilization effectiveness in medical facilities. Regular tests guarantee that class B autoclaves work reliably and meet the highest hygiene standards. This not only increases patient safety, but also continuously monitors and optimizes the quality of sterilization processes. Practices and clinics can thus ensure that their complex hollow instruments are always perfectly sterilized.