Makers of Oxygen Monitors Sue Masimo

Mallinckrodt Inc., the largest maker of respiratory-monitoring equipment, accused rival Masimo Corp. in Irvine of infringing on three patents for instruments that measure blood-oxygen levels through the skin. In a suit filed this week in U.S. District Court in Wilmington, Del., St. Louis-based Mallinckrodt and a subsidiary, Nellcor Puritan Bennett Inc., say they own patents issued in 1987, 1992 and 1998 for oximeters that can fit over a finger or toe to monitor oxygen levels in a medical patient. Mallinckrodt contends Masimo and a distributor, Ivy Biomedical Systems Inc., are wrongly marketing oximeters based on the inventions. Last month, Masimo said it filed a lawsuit in a California federal court charging Mallinckrodt and Nellcor with infringing Masimo’s patented oximeter technology.