Malfunctioning of infusion pumps due to interference from an electrosurgical unit

We observed the incidence of pump errors by the interference from the electrosurgical unit (Vallylab, Force 4B) set at coagulation or cut mode, with three infusion pumps: Terumo STC-523, STC-525 and STC-525-01. The STC-525-01 painted with electrically conductive paint inside was used during electrosurgery on experimental basis. Malfunctioning of the STC-523 pump occurred frequently by using electrosurgical unit set at coagulation mode and placed close to the pump. The STC-525-01 showed markedly lower incidence of malfunctioning. Therefore, the STC-252-01 pump can be used safely during electrosurgery. Additionally, we discovered, through an estimation of radiated electrical field around the electrosurgical unit, the cable of an active electrode was important as an interference source. To minimize electrosurgical interferences, we propose the following recommendations; 1) keeping the infusion pump and its AC line as far as possible from the active electrode cable, 2) keeping the output of electrosurgical unit as low as possible, 3) operating the pump with its internal battery power supply, and 4) monitoring the operation of the pump while using electrosurgery.