Irvine, Calif. Masimo Corp. has filed a patent infringement lawsuit against Mallinckrodt Inc. and its subsidiary, Nellcor Puritan Bennett, alleging that the Minneapolis-based company is using Masimo's patented Signal Extraction technology in its Oxismart XL pulse oximetry products without a license.

The technology is designed to allow accurate monitoring even during patient motion, said Masimo officials, adding that they have licensed the technology to 30 international patient-monitoring-system providers.

C. Ray Holman, Mallinckrodt chairman and CEO, noting that the company's Oxismart XL technology is "fundamentally different" from Masimo's, said the company would "vigorously" defend itself against the lawsuit.-S.H.