Background: Since December 2019, the COVID-19 infection has drastically spread across China and the world, including Japan. Few reports so far have clari ed the prognosis and treatment of critically ill patients managed with invasive mechanical ventilation. This study aimed to present the clinical courses of 20 critically ill patients with invasive mechanical ventilation, which may be valuable for determining future therapies and intensive care of critically ill patients with COVID-19. Methods: In this observational, single-center, cohort study, we included 20 critically ill patients with laboratory-con rmed SARS-CoV-2 infection who were admitted to our hospital ICU and required invasive mechanical ventilation. The patients' general characteristics, laboratory data, treatments, and outcomes were assessed between survivors and non-survivors.Results: Among these 20 patients, 14 patients survived and 6 patients died. The lowest lymphocyte count (93 vs 279/μL, p<0.01) and the lowest platelet count (12 vs 152×10 3 /μL, p<0.01) were signi cantly lower, and the highest KL-6 value (1584 vs 546 U/mL, p=0.02) was signi cantly higher, in the non-survivor group versus the survivor group during the patients' ICU stay. In addition to antiviral treatments and daily proning of the patients, methylprednisolone was administered to all patients to control cytokine storm syndrome following the virus infection. Six patients died from complications such as fungal infection, but no patients died of respiratory failure. As a result, none of the patients required ECMO. Conclusion: This report described the prognosis of COVID-19 patients required invasive mechanical ventilation in a single Japanese critical care center. Multidisciplinary treatments using a single protocol, including antiviral therapies, anti-in ammatory therapies, and respiratory physiotherapies, were effective for critically ill COVID-19 patients who required invasive mechanical ventilation.

In a 71-year-old woman, 2 years and 10 months ago, several nodular shadows with calcification were pointed out in both lung fields on the chest X-ray (CXR). After 1 year and 3 months, abnormal shadows were increased in size on CXR, then, she visited our hospital for detailed examination and treatment. On computed tomography CT), several nodular shadows with partial calcification were observed in both lung fields. CT after 1 year and 1 month (6 months before), showed several circular to slightly lobulated mass ranging in diameter of 6-24 mm around the bronchovascular bundles of both lungs and the peri-lobular area such as subpleural peripheral zone and punctate to dendritic calcification also progressed compared to the previous CT. The thoracoscopic partial left lung resection revealed 2 relatively well-defined nodular lesions with a yellow to brown cut surface. Histologically, the deposition of amorphous eosinophilic substance was found around/in the bronchi and blood vessel's wall of the lesions with partial calcification and/or ossification. A diagnosis of AL-type amyloidosis was made by the immunohistochemical findings. Pulmonary amyloidosis is radiologically classified into (1) nodular, (2) tracheobronchial, and (3) lung parenchymal type (diffuse alveolar septal type) according to the deposition patterns. Dendrite irregular calcification, irregular contours, different sizes 0.5-5 cm mean diameter, are characteristic radiological finding of the pulmonary nodular amyloidosis, and it is important to know that it occasionally shows the significant growth simulating malignant diseases.