Oxygen is a colorless, odorless, tasteless gas that is essential for the survival and all body functions to carry out  smoothly. Oxygen therapy is the administration of oxygen at a concentration of pressure and concentration greater than that found in the atmospheric air. The air contain approximately 21% oxygen. Oxygen is the most important medical gas. Hypoxaemia can cause increased mortality and morbidity especially in the developing countries, still feasible and cost-effective ways to treat hypoxaemia receive little or no attention in current global health strategies. Oxygen as a mode of treatment has been used in for almost 100 years, but in developing countries most of the patients do not have access to oxygen due to financial constraints. Knowledge of the physiology of oxygenation is of key importance in oxygen therapy. Oxygen therapy is more reliable if given by high flow systems. Hence use of high flow oxygen delivery system to be implemented.

Keywords: Oxygen; Hypoxia; Oxygen Toxicity