The assessment of air-inlet filters for intravenous infusions in glass bottles

Abstract

Glass infusion bottles require the influx of air into the containers to replace fluid during administration. A non-absorbent cotton wool plug, situated in the air-inlet set, acts as a filter to remove airborne micro-organisms. an enclosed air space artificially contaminated with viable bacterial spores was used to assess the contamination of intravenous infusions from an airborne source. Only small numbers of spores gained access to the infusion fluids when containers were used with commercially made air-inlet sets. Removal of the filter permitted the entry of spores, the numbers being related to the concentration present in the external air. The efficiency of cotton wool plugs was related to the weight of cotton wool in the air-inlet set. The compression applied to the cotton wool also significantly influenced filter efficiency. Although air-inlet sets were challenged with much higher levels of airborne contamination than would be expected in a hospital environment, results indicate that the air-inlet set should contain sufficient cotton wool. The compression of the filter material should also be considered.