Evaluation of a 5-mum stainless steel filter as an intravenous inline filter or prefilter

The suitability of a 5-mum stainless steel filter as an inline filter or a protective prefilter during simulated i.v. therapy was evaluated using flow rate measurements of two routinely used i.v. fluids and parenteral nutrition fluid. As an inline i.v. filter, the 5-mum stainless steel filter was capable of maintaining suitable flow rates. The addition of antibiotic additives decreased the flow rates slightly but not below the range required for i.v. therapy. Flow rate profiles, however, when compared to a 0.45-mum membrane filter suggest that antibiotic additives contain high numbers of particles in the less than 5-mum range. Consequently many of the particles, especially those in the less than 3-mum range will pass the 5-mum filter. As a protective prefilter, the 5-mum filter device in combination with a 0.45-mum membrane filter provided more uniform flow rates over longer periods of time when additives were employed. Using the aspiration device as a prefilter for adding antibiotics to the infusion fluid resulted in improved flow rates through a 0.45-mum membrane filter for lactated Ringer's containing cephalothin sodium, while for solutions containing ampicillin or oxytetracycline, prefilteration did not change the flow rate profiles.