IDI - Irish Decontamination Institute

Recommendations by the Quality Task Group
[4] Validation (Part 2)

The first validation of a steam sterilisation process is divided into the following steps given here by way of example:

1. COMMISSIONING
   During commissioning tests are conducted to establish whether the preconditions for successful sterilisation are met. These include, inter alia, testing whether the steriliser meets the requirements for installation and connection and whether the operating materials fulfil the requirements of the steriliser manufacturer. To save time and cut costs, commissioning should be omitted if a steam sterilisation process is not being validated for the first time and if no changes of relevance to commissioning have occurred since the time of first validation.

2. VACUUM TEST
   The vacuum test furnishes proof that vacuum tightness of the system is still assured also following introduction of the temperature sensors into the steriliser chamber. In the event of impermissible deviations, their cause must be elucidated and the fault eliminated before further tasks can be carried out.

3. CALIBRATION of the pressure and temperature sensors used during validation
   Calibration serves to prove and document that the sensors are functioning within the permitted tolerances. Calibration must be performed using high-quality test equipment which for its part has also been calibrated. The validity of the test equipment used for calibration should be proven and noted in the documentation.

4. Recording the EMPTY CHAMBER PROFILE
   The empty chamber profile is a temperature measurement with which the temperature distribution can be documented at different measuring points in the non-loaded chamber. Recording of the empty chamber profile can be omitted in agreement with the customer.

5. Definition of the REFERENCE LOAD (sample load)
   The reference load is the load used for validation. It reflects the most difficult combination of items to be sterilised (DIN EN 554). The reference load is the load which corresponds to a large number of different loads otherwise normally used. But due to the large number of sterile items and loads encountered in the CSSD, in practice there are several reference loads with which a process is validated. Later, all sterile supply loads will be based on the validation of these reference loads. The reference loads are generally defined in consultation with the person responsible for the CSSD. It is unusual for the validation expert alone to define the reference loads, and this should be rejected.

6. PERFORMANCE ASSESSMENT
   Based on DIN EN 554 the performance assessment denotes the "search for and furnishing of proof that the commissioned system produces acceptable products when operated according to the process specifications". The assessment performance evaluates the main body of the building, including installation situation and provision of operating materials, the steriliser, sterilisation process, items to be sterilised, packaging and correct operation of the steriliser. Within the framework of the performance assessment, tests are conducted at several locations in the reference load to establish whether the sterilisation temperature has been reached and remains constant within certain limits during the entire sterilisation phase. Moreover, compliance with the sterilisation time is checked. All results must be documented and evaluated. The performance assessment is the most expensive and onerous part of validation.

7. VALIDATION DOCUMENTATION
   The validation documentation contains reports on commissioning and on the performance assessment. It can be compiled entirely or partially using software. The scope of the documentation is defined by the validation expert in consultation with the customer, e.g. the CSSD management. The documentation is checked by the expert for completeness on finishing validation.

8. RELEASE OR BLOCKING of a sterilisation process
   Following successful validation the processes are released by the expert, hence they may now be used. The validation report is handed over to the customer and depending on how the validation test laboratory is organised, a copy of the validation report may be forwarded to the head of the test laboratory for additional evaluation and final release of the process. Insights from the report are incorporated into training programmes for validation experts and are important especially in respect of the knowledge gained for definition of reference loads.
   If the validation outcome for a process does not meet the requirements, the process is deemed not to be validated in respect of the reference load and is blocked by the expert, who duly communicates this to the person responsible for the CSSD. The responsibility for ensuring that the respective combination of process and load is not used is borne by the CSSD management.

Validation cannot be conducted at the premises of the steriliser manufacturer, because the conditions prevailing there are not those encountered at the site of operation. These include, e.g. the installation situation and provision of operating materials which are to be evaluated during commissioning. Furthermore, it is absolutely necessary during validation that the sterile supplies encountered at the site of operation, the packaging and steriliser load be included in the performance assessment.