Could bronchial washing (as used in pulmonary alveolar proteinosis and some forms of pneumonia) be used to treat or at least reduce the length of time a patient suffering from COVID-19 required mechanical respiration?
In addition to alleviating the pneumonia symptoms perhaps the saline flushing solution could be formulated with some type of soaping agent that was still compatible with the respiratory tract since the virus has been shown to be susceptible.
Assuming the procedure could be run continuous on each bronchus for the duration of the virus life cycle (how long is this?) then you could destroy all traces of the virus (unless it remained dormant within a host cell).