System for automatic detection, measurement, and elimination of air from a fluid pathway

A system for detecting, measuring, and removing gas from a medical fluid pathway, the system comprising:

• a fluid delivery path configured to convey therapeutic liquid from a fluid source toward a patient;
• a fluid chamber forming at least a portion of the fluid delivery path and configured to receive therapeutic liquid and entrained gas;
• a gas-selective membrane positioned adjacent to the fluid chamber and configured to permit gas to pass therethrough;
• a pressurized chamber containing a pressurizing medium and positioned to apply positive pressure to at least a portion of the fluid delivery path and a controllable fluid restrictor, so as to establish a pressure differential across the gas-selective membrane that promotes transfer of gas from the fluid chamber through the gas-selective membrane;
• a pressure controller configured to regulate the positive pressure applied by the pressurized chamber;
• and a fluid flow resistance control device to create a hydrodynamic backpressure, configured to regulate the positive pressure applied by the pressurized chamber;
• a pressure sensor configured to measure pressure associated with at least one of the pressurized chamber or the fluid chamber;
• and
• a controller configured to calculate a gas quantity based on a change in measured pressure.

A method for detecting, measuring, and removing gas from a medical fluid pathway, the method comprising:

• conveying a therapeutic liquid from a fluid source toward a patient through a fluid delivery path;
• directing the therapeutic liquid and any entrained gas into a fluid chamber in fluid communication with the fluid delivery path;
• drawing gas from the fluid chamber into a pneumatic chamber through an integral gas-selective membrane that allows gas to pass while retaining liquid in the fluid chamber by imposing and maintaining a controlled negative pressure differential between the pneumatic chamber and the fluid chamber using a pressure controller fluidly coupled to the pneumatic chamber;
• selectively isolating the pneumatic chamber from the pressure controller using a valve to create a sealed measurement volume;
• measuring pressure changes within the sealed measurement volume using a pressure sensor;
• and
• calculating, with a controller, a gas quantity corresponding to the measured pressure change and, in response to the pressure change meeting or exceeding a threshold, causing the pressure controller to re-establish or adjust the controlled pressure differential in the pneumatic chamber.