There is an important development of non-invasive ventilation and nasal high flow oxygen in patients with hypoxemic respiratory failure, especially due to the high incidence of its use in patients (pandemic, emergency department, intensive care unit). However, there are few descriptions of how these strategies should be implemented and a clear definition of methodology in use. In this book, these treatment options are analyzed, providing the reader with a practical and objective vision of their indications and evaluation of results.