A state-of-the art assessment of the different causes of hypoxemia (shunt, ventilation–perfusion mismatch, and diffusion limitation) in COVID-19 acute respiratory distress syndrome (ARDS) is currently lacking. In this study, Busana et al. hypothesized a multifactorial genesis of hypoxemia and aimed to measure the relative contribution of each of the different mechanisms and their relationship with the distribution of tissue and blood within the lung. In an accompanying editorial, Capaccione and Vidal Melo examine the physiologic determinants of hypoxemia, relevant techniques and methods to identify and address hypoxemia, and new research on hypoxemia during COVID-19 ARDS. Cover illustration: A. Johnson, Vivo Visuals Studio.

  • Busana et al.: Causes of Hypoxemia in COVID-19 Acute Respiratory Distress Syndrome: A Combined Multiple Inert Gas Elimination Technique and Dual-energy Computed Tomography Study, p. 251

  • Capaccione and Vidal Melo: Structure–Function Relationships Determining Hypoxemia in COVID-19 Acute Respiratory Distress Syndrome, p. 186