Methods of administering therapeutic gases containing high concentrations of nitric oxide, particularly concentrations above 2,000 ppm. The therapeutic gas may be administered at a certain dosing rate, such as less than 166 micrograms of nitric oxide per second. Also, methods of administering a therapeutic gas containing nitric oxide to a patient, wherein a dose of nitric oxide is administered from a portable device that includes a delivery system and a mini-cylinder. Methods can also include intermittent administration of nitric oxide pulses.