sentences:  Endobronchial valves were developed primarily by the start-up medical device company Emphasys Medical (now Pulmonx - Redwood City, California) as a minimally invasive alternative to lung volume reduction surgery for emphysema.In lung volume reduction surgery, a surgeon cuts into a patient's chest and cuts out one or more diseased portion(s) of a lung.Endobronchial valves were designed to replicate the effects of that procedure without requiring incisions, by simply allowing the most diseased portions of the lung to collapse.