Pump cassette and methods for use in medical treatment system using a plurality of fluid lines

A fluid handling cassette for use in a fluid handling system useable in a medical infusion application, the cassette comprising:

• a generally planar body having at least one pump chamber formed as a depression in a first side of the body and a plurality of flowpaths for a fluid that includes a channel, the at least one pump chamber including a plurality of spacer elements having ends that extend from a flat bottom inner wall of the depression, at least some of said spacer elements varying in height, and said at least one pump chamber including a fluid outlet;
• a patient line port arranged for connection to a patient line, the patient line port being in fluid communication with the at least one pump chamber via at least a first one of said flowpaths;
• a drain line port arranged for connection to a drain line, the drain line port being in fluid communication with the at least one pump chamber via at least a second one of said flowpaths;
• and
• a flexible membrane attached to the first side of the body over the at least one pump chamber, a first portion of the flexible membrane over the at least one pump chamber being arranged to be movable for movement of the fluid in the at least one pump chamber, and second portions of the flexible membrane positioned over respective valves and movable to open and close the respective valves;
• wherein said first portion of the flexible membrane has a shape arranged to conform to a usable area of a corresponding pump chamber while at rest and without being stressed, the usable area of the corresponding pump chamber being defined in part by the plurality of spacer elements, and said plurality of spacer elements are configured to inhibit the flexible membrane from covering the fluid outlet.

A fluid handling cassette for use with a fluid handling system of a medical infusion device, the cassette comprising:

• a generally planar body having at least one pump chamber formed as a depression in a first side of the body and a plurality of flowpaths for a fluid that includes a channel, the at least one pump chamber including one or more spacer elements having ends that extend from an inner wall of the depression, at least some of said spacer elements varying in height;
• a patient line port arranged for connection to a patient line, the patient line port being in fluid communication with the at least one pump chamber via at least a first one of said flowpaths;
• a drain line port arranged for connection to a drain line, the drain line port being in fluid communication with the at least one pump chamber via at least a second one of said flowpaths;
• and
• a flexible membrane attached to the first side of the body over the at least one pump chamber, the flexible membrane being sealed against a periphery of the body to prevent the fluid from leaking from the cassette, a first portion of the flexible membrane over the at least one pump chamber being arranged to be movable for movement of the fluid in the at least one pump chamber, and second portions of the flexible membrane positioned over respective valves and movable to open and close the respective valves, said first portion of the flexible membrane having a shape arranged to conform to a usable area of a corresponding pump chamber while at rest and without being stressed, the usable area of the corresponding pump chamber being defined in part by the one or more spacer elements;
• wherein the body includes a vacuum vent clearance depression formed adjacent to, extending from, and in fluid communication with the at least one pump chamber, said vacuum vent clearance depression configured to allow a vacuum vent port of the medical infusion device to remove air or a fluid between the flexible membrane and a control surface of the medical infusion device when the fluid handling cassette is installed in the medical infusion device.