An open system provides breath-synchronized, flow-targeted ventilation to augment respiration by a self-breathing patient. A sensor detects a physical property of a patients respiratory cycle. A processor monitors the sensor and controls a gas source to deliver oxygen-containing gas through a tube extending into the patients airway with the flow rate varying over each respiratory cycle in a predetermined non-constant waveform synchronized with the respiratory cycle to augment the patients spontaneous respiration. Gas is delivered at a flow rate sufficient to significantly mitigate the airway pressure the patient must generate during spontaneous breathing and thereby reduce the patients work of breathing.
