American journal of respiratory and critical care medicine, 197(9), 1198-1208. American Thoracic Society American Journal of Respiratory and Critical Care Medicine American Journal of Respiratory and Critical Care Medicine, 197(9), 1198. American Thoracic Society American journal of respiratory and critical care medicine, vol 197, iss 9 American Journal of Respiratory and Critical Care Medicine, 197(9), 1198-1208