Conceptions of the pathophysiology of happy hypoxemia in COVID-19.

In their letter-to-the-editor entitled "Misconceptions of pathophysiology of happy hypoxemia and implications for management of COVID-19", Tobin et al. (Respir Res 21:249, 2020) debated our views on happy hypoxemia in COVID-19 (Respir Res 21:198, 2020). We thank the authors for their interesting comments and alternative viewpoints, and we would like to clarify several important aspects raised.