Patent ID: 7255680
Filing Date: 2007-08-14
Classification: A61M

Abstract:
1. An apparatus for pumping infusion fluid from a first fluid container having an output communicating with a conduit, said apparatus comprising: a second fluid container positioned adjacent to the first fluid container and configured for application of pressure to the first fluid container to expel the fluid from the first fluid container; a flow control actuator coupled to the conduit for controlling the desired flow rate; a pressure sensor coupled to the second fluid container adapted to sense pressure in the second fluid container and provide a pressure signal in response to the pressure sensed; a flow sensor coupled to the conduit and adapted to sense fluid flow in the conduit and provide a flow signal in response to the fluid flow sensed; and a processor operatively coupled to said second fluid container for controlling said application of pressure and operatively coupled to said flow control actuator for controlling said desired flow rate, wherein said processor is configured to determine the downstream resistance in the conduit by selectively applying a plurality of pressure values to said second fluid container to obtain a plurality of pressure signals from said pressure sensor and a plurality of flow signals from said flow sensor, and wherein said processor computes said downstream resistance using a quotient of the difference between two of said plurality of pressure signals and a corresponding two of said plurality of flow signals.