A reduced pressure treatment system compri si ng: a compressible chamber positionable beneath a foot of a user and being movable between an expanded position and a compressed position, the compressible chamber having an inlet and an outlet; an inlet valve in fluid communication with the inlet to prevent fluid within the compressible chamber from exiting the inlet; an outlet valve in fluid communication with the outlet to prevent fluid from entering the compressible chamber through the outlet; a biasing member disposed within the compressible chamber to bias the compressi bl e chamber toward the expanded position; a manifold positionable at a tissue site and configured to be in fluid communication with the inlet of the compressible chamber, characterized in that the system further includes: a pressure regulator fluidly connected between the compressible chamber and the manifold to regulate the reduced pressure delivered to the tissue site, wherein the pressure regulator includes a first variable-volume cavity and a second variable-volume cavity, the first variable-volume cavity being fluidly connected to the compressi bl e chamber, and wherein the first variable-volume cavity and the second variable-volume cavity share a common piston wall that is moveable between a retracted position and an extended position to vary the volume associated with the first variable-volume cavity and the second variable-volume cavity. a compressible chamber positionable beneath a foot of a user and being movable between an expanded position and a compressed position, the compressible chamber having an inlet and an outlet; an inlet valve in fluid communication with the inlet to prevent fluid within the compressible chamber from exiting the inlet; an outlet valve in fluid communication with the outlet to prevent fluid from entering the compressible chamber through the outlet; a biasing member disposed within the compressible chamber to bias the compressi bl e chamber toward the expanded position; a manifold positionable at a tissue site and configured to be in fluid communication with the inlet of the compressible chamber, characterized in that the system further includes: a pressure regulator fluidly connected between the compressible chamber and the manifold to regulate the reduced pressure delivered to the tissue site, wherein the pressure regulator includes a first variable-volume cavity and a second variable-volume cavity, the first variable-volume cavity being fluidly connected to the compressi bl e chamber, and wherein the first variable-volume cavity and the second variable-volume cavity share a common piston wall that is moveable between a retracted position and an extended position to vary the volume associated with the first variable-volume cavity and the second variable-volume cavity. a pressure regulator fluidly connected between the compressible chamber and the manifold to regulate the reduced pressure delivered to the tissue site, wherein the pressure regulator includes a first variable-volume cavity and a second variable-volume cavity, the first variable-volume cavity being fluidly connected to the compressi bl e chamber, and wherein the first variable-volume cavity and the second variable-volume cavity share a common piston wall that is moveable between a retracted position and an extended position to vary the volume associated with the first variable-volume cavity and the second variable-volume cavity.