Resting blood pressure Pulse oximetry before, during, and after exercise (using the Masimo Radical 7 pulse oximeter, K120657) Comfort level with walking, Perceived Exertion Level (modified Borg scale) Resting, exercise and post-exercise Shortness of Breath (modified Borg scale) Data Analysis The trial is powered to demonstrate feasibility of RDS in maintaining targeted oxygen saturations in hypoxemic patients with exercise.