Oxygen Therapy: Systems and Indications in the Pediatric and Adult Population

Hypoxemia is defined as the decrease in arterial partial pressure of oxygen (PaO2) below 80 mmHg. One of the ways to alleviate this condition is through oxygen therapy, which consists of administering oxygen at a concentration higher than atmospheric. This therapy is indicated in various pathologies and is aimed to treat hypoxemia and reduce the patient's myocardial demand and respiratory effort. Classically, this treatment has been carried out using low-flow systems, in which the inspiratory fraction of oxygen (FiO2) cannot be regulated. However, an increase in the use of high-flow oxygen therapy (HFO) has been observed in recent years. These systems allow for greater patient comfort as well as more precise regulation of the FiO2. The purpose of this article is to review respiratory physiology to understand respiratory failure from a clinical and pathophysiological point of view. Likewise, the different oxygen therapy systems most widely used are discussed, as well as their indications for acute and chronic pathologies, both in the pediatric and adult populations.