Particulate air quality in the insulator throughout a production period. Factors impacting contamination.

23 November 2020


Microbiological contamination (risk for the sterility of our preparations) is intimately linked to particulate contamination, as particles are possible vectors for micro-organisms. To control air quality, Good Preparation Practices require that the air inside the work area to be qualified as Class A. In the hospital environment, this qualification is done during inactivity time and periodically (at least once a year). We therefore do not know what happens inside the isolator as the day progresses.

To carry out a continuous monitoring of the number of particles in the isolator in order to know the exact air quality during the production period. At the same time, acts potentially generating particles were monitored to assess their impact.

Materials and methods
Using a particle counter (0.5 and 5µm), samples were taken every 10 minutes in the isolator enclosure (single station; under vacuum; work by tended flow baskets) throughout the production day. These analyses were repeated 2x (i.e. 2 days) for the 5 isolators in the preparation area. Simultaneously, the following criteria were followed and notified in order to characterize the sample: isolator on inactivity time (e.g. pause of the manipulator); shaking/reconstitution of a vial; torn and/or peeled packaging; entry of 4 baskets (= isolator filled to the maximum); handling of the shell, tubing or waste bin; placement of the opabag®; opening of the 25 spikes pouch, long preparation/end of preparation. The significance of the impact of these criteria was objectivized by a test by Kruskal Wallis.

284 samples were taken, 213 during activity time, 71 in the inactivity time. During inactivity time, 100% of the samples validated the class A criteria. During activity time, the air in the isolator is systematically in class B. For 0.5 and 5µm particles, 5 criteria have a significant negative impact on air quality: insulator loaded to maximum; handling of shells, dustbins and tubing; opening of spike pouch.

Conclusion, discussion
This study enabled us a better understanding of the particulate contamination within our isolators and in particular the capacity of our ventilation systems to systematically return to class A within 10 minutes after the enclosure is put to rest.
During the periods of activity and in accordance with the criteria identified as having an impact on the number of particles, we are going to limit the use of shells, tubing and dustbins as much as possible during the act of preparation. Consideration will be given to multi-conditioning (spikes) and the need for a rest period after opening. Finally, a better distribution of the load on the insulators will be studied.

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