The ROX Vector App is designed to visualise changes of respiratory rate and fraction of delivered oxygen in the vector form. The application calculates ROX index by dividing peripheral oxygen saturation by fraction of oxygen and by respiratory rate. The index has been proposed to predict success of nasal high flow therapy in patients with hypoxemic respiratory failure. The ROX Vector App can also be used as a simulation tool for reviewing various clinical scenarios. The data are stored in the device only and can be exported in xlsx format via email.