Multi-zone falling washer blood clot detection

US9429563B2 · kind B2 · utility

Assignee

• Medtronic, Inc. · US

Inventors

• Daniel Cheek · Plymouth, US
• Lawrence Erickson · East Bethel, US
• Trevor Huang · Maple Grove, US
• Tessy Kanayinkal · Brooklyn Park, US
• Craig Petersen · Shoreview, US
• Charlene Yuan · Plymouth, US

Key dates

• Filing date: Dec 6, 2012
• Grant date: Aug 30, 2016
• Expiry date: Dec 6, 2032

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N33/86
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Activated clotting time (ACT) tests detect blood clotting time based on the viscosity changes of a test sample, using a ferromagnetic washer lifted to the top of a test chamber and then dropped from the top via gravity; a drop time greater than a preset threshold value indicates clotting of the test sample. Blood samples which have high levels of heparin usually produce very weak clots that may easily be destroyed by the lifting movement of the washer. But if the clot threshold is set low to detect the weak clots, false detections occur during early testing cycles when activators are not fully suspended during the mixing cycle. Improved algorithms for lifting the washer and adjusting over time enable accurate detection of weak clots.