Introduction
Coronavirus disease 2019 (COVID-19) is a viral respiratory tract infection caused by a coronavirus which was first documented in Wuhan, China, in December 2019 (1)
After then, this outbreak spread globally and has been considered as a pandemic and an international public health emergency by the WHO since March 11, 2020. As of 6th of September 2020, a cumulative total of 27,083,427 confirmed cases of coronavirus disease 2019 (COVID-19) were reported with total 884,029 deaths in 203 countries and territories worldwide (2). Currently, there is neither a proven effective medication nor a vaccine has been discovered for the COVID-19 infection.
Although most patients with COVID-19 infection have only mild or uncomplicated course, around 10-20% will develop a severe disease that necessitates hospitalization and oxygen therapy or even ICU admission and progression to acute respiratory distress syndrome (ARDS). The prevalence of ARDS caused by COVID-19 is around 8.2% who will require mechanical ventilation and prone positioning (3) . Furthermore, hyperinflammatory state by cytokine storm appears to be a solid part of severe COVID-19 disease (4)
However, a group of patients will suffer from persistent hypoxemia and intractable ARDS despite maximum conventional treatment with mechanical ventilation and mortality among this subgroup is markedly high. Initial reports from China, Italy and USA suggest high patient admission to intensive care units (ICU) and mechanical ventilation with shockingly very high mortality rate among patients with severe ARDS due to COVID 19