Requirement of the European Medical Device Directive (MDD) 93/42 ECC
Sterility of goods coming out of a sterilizer cannot be checked before use. To assure sterility of products coming out of a sterilization process a validation process is required. It is required to assure, that:
1 products coming out of the sterilization process are sterile with a sterility assurance level of SAL ≥ 10-6 CFU (according to EN 556)
2 Reproducibility of sterility is guaranteed over a long time
Most people believe that “sterilizers are validated” and after this job is carried out necessarily all products coming out of that sterilizer are always sterile. This is not correct. A sterilization machine can never be validated but only a sterilization process. Besides other details a sterilization process includes:
- • Cleaning
- • Disinfection
- • Functional check
- • Sterilization process including:
- – Sterilizer and supply media
- – Program used
- – Goods to be sterilized
- – Packaging material and packaging procedure
- • Storage
- • Transportation to the end-user
- • Quality Management System
All components working together define a sterilization process. If one important item of the sterilization process is changed (e.g. a solid instrument against a complex minimal invasive
surgical (MIS-) instrument) this is a new process even if the same program is used.
Depending on the goods sterilized, their bio burden and packaging an adequate sterilization program has to be designed according to the application. In healthcare standard programs (steam 134°C ≥ 3 min or 121°C ≥ 15 min) are used. On top the kind of air removal and steam penetration plays an important role to control how good the steam is penetrated inside the packaging between the goods and inside hollow instruments and tubes. If instruments cannot be sterilized at such high temperatures low temperature sterilization processes using chemicals (ETO, formaldehyde, H2O2) can be used. All these sterilization programs can sterilize and have advantages. But all of them have limitations too. These limitations must be known and/ or be detected by carrying out a validation procedure.
A validation of a sterilization process is carried out in several steps:
- 1 Installation qualification (IQ)
- 2 Operational qualification (OQ)
- 3 Performance qualification (PQ)
1 Installation qualification (IQ)
When a new sterilizer is installed the company installing this machine has to make sure that the machine is working according to the specifications agreed on when sold. The selection of specifications is important to assure that the process is adequate to the sterilized products later on. For hospital sterilizers it is recommended to use a sterilizer according to EN 285. For small sterilizers it is recommended to use a sterilizer according to EN 13060. Depending on the type of products sterilized small sterilizer of type B, N or S has to be selected.
2 Operational qualification (OQ)
The operational qualification has to make sure that the sterilizer works correctly with all the necessary components (like: cooling water, steam, electricity etc). In steam sterilization processes one important part is the quality of the steam. The amount of non-condensable gases in steam heavily influences the quality of the efficacy and security of adequate steam penetration. According to the standards EN 285 and EN 13060 specific tests are carried to assure that the sterilizer is running according to its specifications.
3 Performance qualification (PQ)
If the sterilizers run according to their specifications it is not automatically guaranteed that all products are sterilized. Depending on the complexity of the products an adequate sterilization program has to be selected. In steam sterilizers, the air removal and steam penetration of that sterilization processes is absolutely important and must be adapted to the type of instruments, the packaging and load configuration. This process must assure that all products coming out of the sterilization process are sterile according to EN 556 (SAL ≤ 10-6 CFU). To assure this, specific tests have to be carried out using parametric release, chemical and biological indicators at the right place, specific process challenge devices (PCDs) and sometimes inoculation of the goods at the worst case with biological indictor suspensions with the following biological evaluation after the sterilization.
Routine monitoring After the sterilization has been carried out successfully it must be assured that the process being validated once is afterwards running correctly the same way. To guarantee the
permanent reproducibility an adequate routine monitoring is necessary. “Adequate” means that the type of monitoring selected heavily depends on the complexity of the sterilization process.
In steam sterilization processes the temperature- and pressure/ time parameters are monitored and recorded. Those parameters guarantee a minimum of security. However, those parameters are not able to guarantee that the sterility is carried out in all areas of the chamber. Unfortunately, in steam sterilization processes, the steam distribution inside the chamber is not homogeneous. It heavily depends on several process parameters. Therefore the steam penetration into the worst case areas of the process (usually the middle inside of hollow instruments) needs to be monitored in addition. For these special cases so-called process challenge devices (PCDs) including a chemical and/ or biological indicator are used for routine monitoring.
If a patient gets a nosocomial infection, it may be caused by several reasons. To exclude nosocomial infection caused by non-sterile instruments both: the documentation of the validation of the process and also the information of the protocols of routine monitoring must be presented to assure sterility. This information must be documented for each batch and has to be stored in the CSSD.
The above information must be patient related. To achieve this requirement double selfadhesive labels with all necessary information may be used to be adhered at the pack. When the package is used – the label from the pack may be transferred to the patient’s documentation without any additional writing.