• respiratory
• pneumonia/infections

Dear editor

The pathogenSARS‐CoV‐2 (also known as 2019‐nCoV) is a novel coronavirus, primarily affecting the respiratory system.1 2 As it is the first time that it has caused infection in humans, information about the pathophysiology of the disease is limited. The most common cause of hospitalisation is pneumonia, and the most severe complication is acute respiratory distress syndrome (ARDS) for SARS‐CoV‐2 infected patients.1–3

Clinical and radiological findings of COVID-19 pneumonia are diverse.1–3 To date, in the literature, some patients have shown relatively good clinical progress and some have developed respiratory failure and ARDS. Interestingly, some patients who had severe clinical and radiological findings have been successfully treated with supportive therapy, including oxygen support, with or without treatment in the prone position.1 2 4

The physiopathological process in ARDS with an atypical clinical course may differ from classic ARDS.1–3 A few reports have tried to provide evidence on this issue but there are not enough studies in the literature. For example, Gattinoni et al identified two types of ARDS phenotypes, L and H types, in their study.3 They also suggested that perfusion might primarily be disrupted in the first type and ventilation in the second.

Bilateral diffuse infiltration and atelectasis have been frequently seen in COVID-19 pneumonia. Sticky mucus, epithelial damage and surfactant deficiency are the leading causes of hypoxaemic respiratory failure …