A method for increasing circulation in a breathing person utilizes a valve system that is interfaced to the person's airway and is configured to decrease or prevent respiratory gas flow to the person's lungs during at least a portion of an inhalation event. The person is permitted to inhale and exhale through the valve system. During inhalation, the valve system functions to produce a vacuum within the thorax to increase blood flow back to the right heart of the person, thereby increasing cardiac output and blood circulation.