The authors used in clinical practice an infusion pump driven by a rotation system with an occlusive pathway whereby the movement of the rotor is ensured by a stepper with reduction of the steps to 12,800 microsteps per revolution. As regards the degree of mechanical damage of the inserted tube of the infusion set this system did not differ from the keyboard system which is used by the majority of manufacturers as the driving unit of infusion pumps. Mechanical damage of the infusion set made from PVC was evaluated by the authors with regard to the amount of phthalic acid extracts which are added to PVC as softening agents and are not chemically linked. The authors recorded an increase of the temperature of the infusion solution during the flow through the driving unit in both investigated systems, however, the increase was smaller in the keyboard system. The increase of temperature was, however, in both instances small and has no impact on clinical practice. Contrary to the infusion pump with the keyboard system, the infusion pump with a rotor in an occlusive pathway and a microstep motor (12,800 microsteps per revolution) was significantly more accurate as regards dosage (evaluated as the difference between the required and actually achieved value of flow). The revealed difference was statistically significant at the 1% level. This greater precision of dosage can be ascribed to the point compression of the inserted and to the microvibrations transmitted from the rotor to the inserted tube of the infusion set which helps to recover after every compression the original volume (circular shape of section) of the inserted tube.

Keywords: Diethylhexyl Phthalate /analysis/; Equipment Design; Infusion Pumps