Disclosed is a chest drainage system which reduces or eliminates pooling of blood/liquid and/or clogging/clotting in the drainage tube. Generally, the chest drainage system continuously monitors chest tube status and clears pooled liquid when necessary to restore negative pressure to the chest. The system may include a valve device which is located between the patient's chest tube and drainage tube and may be used with any standard chest tube. The chest drainage system also includes a controller for monitoring the pressure at or near the valve device and/or at or near the suction device, and possibly a pump for assisting in clearance of pooled liquid and/or clots. The controller may also control the valve device and/or suction device in response to pressure signals.