Assessment of the microbiological impact of an isolator failure on the working environment

Context
In the Production Department of our Hospital Pharmacy, high-risk preparations are carried out in controlled area. The equipment used is mainly vacuum isolators to prevent chemical contamination of the environment. Following an isolator failure, questions about the maintenance of sterility in the working environment are raised by pharmacists and pharmaceutical-technical assistants.

Objectives
The primary objective is to define the various problems that can lead to the failure of an isolator and prevent them through the implementation of appropriate actions. The secondary objective is to determine the microbiological impact of an isolator failure on the working environment. These 2 objectives have a common goal: to identify and eliminate the potential risks associated with a failure of the isolator, thus reducing the impact on the quality of the preparations.

Methods
In order to identify most of the causes of an isolator failure, 2 Ishikawa diagrams are made: the first to identify the causes of non sterility of preparations and the second to identify the causes of equipment failure. A FMECA is then carried out, based specifically on a brainstorming session. Finally, a test protocol is written to evaluate the microbiological impact of an isolator failure on the working environment. An isolator is switched off and an environmental monitoring is carried out for 5 consecutive days.

Results
During the FMECA, 29 failures were identified and distributed as follows: People (4), Maintenance (2), Equipment (11), Material (6), Method (1) and Environment (5). Of these failures, 5 are negligible (17%), 19 are acceptable (66%) and 5 are unacceptable (17%). However, results for the microbiological impact assessment are not yet available.

Conclusion
The implementation of this quality approach makes it possible to identify and quantify the potential risks associated with an isolator failure. In addition, the results of the microbiological impact measurement will help determine how long an isolator can be used following a failure.

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