Improving Anticoagulation Monitoring in Pediatric Patients: Use of a Microfluidic Platform to Test Low Volume Blood Samples Obtained by Heel-Stick Collection

ABSTRACT Improving Anticoagulation Monitoring in Pediatric Patients: Use of a Microfluidic Platform to Test Low Volume Blood Samples Obtained by Heel-Stick Collection Children treated for congenital heart defects or other disorders of hypercoagulation are prescribed unfractionated heparin (UFH) or low molecular weight heparin (LMWH) throughout surgical treatment; they may be prescribed heparin for up to 2 weeks post-surgery to prevent thrombosis. UFH is a fiscally efficient, effective anticoagulant that should be closely monitored over time to ensure proper dosage and patient response; LMWH is a newer anticoagulant that is gaining traction among cardiologists. Despite the need for constant monitoring of heparin levels, sometimes every 4 hours, there are limitations to currently available systems hindering delivery of optimal heparin level results to physicians. These barriers include individual assays that use relatively large volumes of blood (~2 mL per assay) and long turnaround times between measurements (up to 2 hours) that limit the utility of these tests for appropriate dosing, especially in the beginning of anticoagulation therapy. In addition, commonly utilized assays (partial thromboplastin time (PTT), activated PTT (aPTT), and prothrombin time) show poor correlation to heparin levels infused in patients, but are still in use due to their historical value and wide adoption in the field. More rapid and accurate methods are needed to assess heparin levels that reduce the overall amount of blood and provide physicians with sufficient dosing information to deliver optimal therapy to pediatric patients. Through a previously funded NIH Fast-Track project, we developed a novel and scalable platform to assess and monitor heparin therapy administered to pediatric patients through measurement of Factor Xa (FXa) and Anti- thrombin III (ATIII) levels. In response to input from key opinion leaders, we are developing a third assay for aPTT. This assay panel is run on our near-patient digital microfluidic (DMF) platform using 50 L of whole blood input. The fluorescent assays use nanoliter volumes of sample and reagents on a disposable single-use cartridge. Although the platform has been developed and feasibility has been demonstrated with the assays, much work remains for this product to be commercially ready. Funding through this Commercialization Readiness Pilot (CRP) will support studies to establish reliable reagent and cartridge manufacturing processes, preclinical studies to validate the manufacturing processes, and development of the FDA regulatory strategy for a full multi-site clinical method comparison study. Our approach is strengthened by our continued partnership with Boston Children’s Hospital, the high potential clinical impact of the tests, and thorough analysis and global distributor relationships demonstrating a significant market gap. The DMF heparin monitoring product will fill a critical gap in pediatric care by providing an inexpensive rapid, low-blood volume system for comprehensive assessment of heparin levels in a hospital or clinic setting. The successful completion of these CRP aims will accelerate commercial development so that we are poised to immediately complete final validation studies for regulatory approval and commercial.PROJECT NARRATIVE Pediatric patients with congenital heart defects or other hypercoagulation disorders require administration of heparin during treatment; heparin is often used post-surgery for weeks to prevent thrombosis and heparin levels must be monitored multiple times per day to ensure efficacy and patient safety. There are numerous limitations to current heparin monitoring systems including large blood volume draws, slow time to result, lack of clinically actionable assay panels, and cost of tests. Our CRP SBIR project builds upon our Phase II success developing a novel near-patient screening platform to support rapid, low-blood volume, and highly comprehensive heparin monitoring. The validation and commercialization of this product will allow for critical monitoring in pediatric populations and will potentially lead to improved health outcomes and reduced cost.