An inspiration-triggered delivery system for oxygen therapy via a nasal cannula

Therapy for severe chronic lung disease currently includes the administration of supplemental oxygen to prevent breathlessness and tissue hypoxia. Although effective, this therapy is unnecessarily costly, because oxygen is administered to the patient during expiration as well as inspiration. To eliminate this inefficiency, a delivery system that senses the inspiratory effort and delivers oxygen to the patient only during inspiration was developed. The 11 X 5 X 8-cm flow control unit attaches easily to a portable oxygen supply. The components of the system have an expected life of five years, and the 9-V battery provides power for about one month of use. Manual controls permit accommodation to the respiratory pattern of the patient. Preliminary evaluation of the system showed that its effectiveness in producing tissue oxygenation is similar to that of continuous oxygen systems. The system has potential applications in ambulatory oxygen therapy and in other clinical settings to improve the cost/benefit ratio of oxygen treatment.