We have read with great interest the article recently published by Zaccagnini et al. [1], entitled "Correlation of non-invasive oxygenation parameters with PaO2/FiO2 ratio in patients with COVID-19 associated ARDS", where they conclude that the SpO2/FiO2 (S/F) ratio is a reliable, non-invasive and easy to track parameter, to monitor patients with coronavirus disease 2019 (COVID-19) with moderate and severe acute respiratory distress syndrome (ARDS), potentially useful to reduce the need to place arterial catheters and the possible consequent thrombotic complications related to COVID–19, so we consider it important to add some comments on this topic.
