Studies on the microbiological safety of the valved side-port of the 'Venflon' cannula.

A randomized prospective study was conducted to assess the effect of inserting a bacteria-retaining filter into the side-port of 'Venflon' cannulae. Observations were made on 109 cannulae with filters and 100 without. Although there was a trend towards a reduced rate of side-port colonization in the cannulae with filters this was not paralleled by any reduction in the incidence of local inflammation or colonization of the intravascular segment (IVS) of the cannula. Of the 37 cannulae with positive cultures from the skin at the cannula insertion site 22 yielded indistinguishable bacteria from the IVS, while only three of the 25 positive side-port cultures were similarly associated. It is concluded that in the majority of cases, organisms isolated from the IVS originate on the skin and that organisms introduced via the side-port rarely lead to IVS colonization.