ARDS was first identified during the Viet Nam war. It used to be called wet lung, shock lung, or DaNang lung. It occurred within 12 to 24 hours following trauma, or 5 to 10 days following sepsis that involved shock (thus the name shock lung). When cases of apparent pulmonary edema(accumulation of fluid in lungs) were not responding to typical therapy, they discovered that they were dealing with more than simple edema. The capillaries of the lungs had become permeable to blood, so bleeding was also occurring in the lungs. At the same time, the blood was clotting. So, bleeding and clotting were both present in the lungs. Gas exchange in the air sacs (alveoli) was severely reduced, and many died before the correct treatment was discovered. They found that by administering anticoagulants (blood thinners) along with steroids (to reverse the porosity of capillaries) they could treat the bleeding and clotting. In order to get air both in and out of the alveoli, they needed a special type of ventilator called PEEP which stands for positive end -expiratory pressure. Today we know this can happen not only following trauma or sepsis, but following other disorders, such as blood and metabolic toxic disorders, drug overdoses, aspirations, etc. Pneumonia is any inflammatory disease involving the filling of alveoli with fluid and/or blood cells. ARDS shares in many characteristics of pneumonia, but is not considered to be a form of pneumonia. ARDS can develop during a bout of pneumonia.