Supplemental oxygen therapy is the delivery of oxygen at a concentration higher than room air (which contains about 21 percent oxygen, an FiO2 of 0.21) to treat or prevent hypoxemia. It is one of the most commonly administered therapies in nursing practice, and although oxygen is given routinely, it is a drug: it has indications, dose ranges expressed as flow rate or FiO2, target saturation goals, and real hazards when misused. Safe oxygen therapy is therefore a core, frequently tested nursing responsibility. The purpose of supplemental oxygen is to maintain adequate tissue oxygenation by keeping the arterial oxygen saturation (SpO2) within an ordered target range — generally 94 to 98 percent for most acutely ill adults, and 88 to 92 percent for people at risk of carbon dioxide retention, such as those with chronic obstructive pulmonary disease (COPD). Oxygen is titrated to the lowest amount that achieves the target, because both too little and too much oxygen cause harm. Oxygen delivery devices are grouped into two broad categories that the NCLEX-RN expects you to distinguish: - Low-flow systems (nasal cannula,...