HMOX1 and COVID-19: While heme metabolism is affected by hypoxia, mainly through reduced expression of heme oxygenase-1 and 2 (46), there was no significant difference in the PaO2/FiO2 ratio, which is a measurement of lung disease severity based on blood and lung oxygenation, between COVID-19 and non-COVID-19 sepsis patients (Table 1).