An overview of acute lung injury in general and in particular viral infections with specific reference to nebulized surfactant and anticoagulation

Abstract

The coronavirus 2 (SARS-CoV-2) has resulted in an international pandemic. The SARS-CoV-2 affects cardiovascular, digestive and urogenital systems. In an attempt to develop a multimodal and targeted approach to the pathophysiology associated with viral lung injury, we reviewed lung histopathology, inflammation, surfactant biology and pathophysiology related to viral associated acute lung injury (ALI / ARDS). Histopathology of viral pneumonia/ARDS cases of the past 100 years has revealed that lung parenchymal and vascular pathologic changes described in the 1918 influenza pandemic, are no different from the histopathology observed in other viral pandemics. Given the inflammatory storm which can occur in COVID-19 infection, the patient is a candidate to develop the classic multi-organ dysfunction and / or failure (MOD/F) which may well include ALI and ARDS. Because there is a well described temporal change in the pathophysiology associated with ALI /ARDS, a "one size fit al" remedy will not suffice, hence our attempt at a targeted functional approach. For instance, variable results in adults treated with surfactant have relegated the use of surfactant in adult ARDS to an uncertainty. We speculate that early and repeated surfactant installation in adults is required in adults. Surfactant may also have beneficial effects on the inflammatory process in the ARDS lung. The increased clotting tendency associated with the inflammation (and ARDS), particularly the effect on the lung vasculature (acute pulmonary hypertension and increased dead space), causes mechanical pressure overload (and failure) of the right ventricle and mechanical respiratory failure. Active management of these should include inhibition of the accelerated coagulation and thrombolysis (via nebulization) and early inotropic support.