[Filtering effectiveness of conventional 15 m micron filters (DIN 58362) and newly developed 15 m micron and 5 m micron filters. I: Particle count].

When i.v. solutions are used, a considerable amount of particulate matter is washed into the patient. This particulate matter consists mainly of glass from ampoules, plastic materials from infusion sets, rubber from the rubber stoppers of infusion bottles and various materials, partly derived from the manufacturing process of the solutions. A new method of particle counting is introduced here (modified thrombocyte counter, Becton Dickinson), whereby particulate matter (less than 2 microns, greater 0.8 microns) could be counted for the first time. Using this counting method, the efficiency of the standard filtration (DIN 58362) was tested. Also tested were 2 new final filtration systems (with 15 microns and 5 microns pore-size). All 3 filtration methods were shown to be ineffective; especially small particles (less than 2 microns) cannot be eliminated by these filtration methods.