Patent ID: 7976486

Claim:
A circulation facilitating apparatus comprising: a pneumatic assembly comprising, a pump assembly; a control assembly for controlling the pump assembly, the control assembly including microprocessor means and means for programming the microprocessor means; an air controller assembly coupled to the pump assembly; and means for energizing the pump assembly, the control assembly and the air controller assembly; a first and a second leg assembly, each leg assembly comprising: a housing for attaching the respective leg assembly to a respective leg of a patient; a bladder assembly having a first chamber, a second chamber and a third chamber; and an air passage assembly having, a first passageway having a first component and a second component, a second passageway having a first check valve, a third passageway having a second check valve, the second check valve having a lower opening pressure than the first check valve, a return passageway, a differential piston having a first inlet, a second inlet, an outlet and a piston member, the piston member positionable in a first position wherein fluid communication is established between the first inlet and the outlet and in a second position wherein fluid communication between the first inlet and the outlet is substantially precluded, and a return vent passageway assembly, wherein the first component of the first passageway extends from the pump assembly to the first inlet of the differential piston, the second component of the first passageway extends from the outlet of the differential piston to the first chamber, the second passageway extends between the first chamber and the second chamber, the third passageway extends between the second chamber and the third chamber, the return passageway is positioned between the third chamber and the second inlet of the differential piston, and wherein the return vent passageway assembly includes a vent passageway extending between each chamber and the first component of the first passageway, each vent passageway including a check valve which opens when the pressure in a respective chamber exceeds the pressure in the first component in the first passageway.