Abstract: A blood filtration system can be used with an external infusion pump and can include, among other things, a withdrawal line, an infusion (return) line, a filter coupled between the withdrawal line and the infusion line, a controller, and a withdrawal pressure sensor and/or an infusion pressure sensor. The withdrawal pressure sensor can sense a withdrawal pressure signal indicative of a pressure in the withdrawal line. The infusion pressure sensor can be coupled to the infusion line to sense an infusion pressure signal indicative of a pressure in the infusion line. In various embodiments, the controller can detect an operational state of the external infusion pump by analyzing at least the withdrawal pressure signal and/or the infusion pressure signal.