Patients with respiratory ailments may breathe easier. An implantable artificial lung could one day help patients with critical cases of emphysema, pulmonary fibrosis, and other chronic respiratory diseases. A new device (tested in sheep) uses the heart's own pumping power rather than a mechanical pump to oxygenate blood. In humans, an artificial lung would be used as a bridge for patients awaiting a lung transplant. Some 80% of patients now die while waiting for lung donation.