title: A System for Simple Real-Time Anastomotic Failure Detection and Wireless Blood Flow Monitoring in the Lower Limbs.
abstract: Current totally implantable wireless blood flow monitors are large and cannot operate alongside nearby monitors. To alleviate the problems with the current monitors, we developed a system to monitor blood flow wirelessly, with a simple and easily interpretable real-time output. To the best of our knowledge, the implanted electronics are the smallest in reported literature, which reduces bio-burden. Calibration was performed across realistic physiological flow ranges using a syringe pump. The device's sensors connected directly to the bilateral femoral veins of swine. For each 1 min, blood flow was monitored, then, an occlusion was introduced, and then, the occlusion was removed to resume flow. Each vein of four pigs was monitored four times, totaling 32 data collections. The implant measured 1.70 cm3without battery/encapsulation. Across its calibrated range, including equipment tolerances, the relative error is less than ±5% above 8 mL/min and between -0.8% and +1.2% at its largest calibrated flow rate, which to the best of our knowledge is the lowest reported in the literature across the measured calibration range. The average standard deviation of the flow waveform amplitude was three times greater than that of no-flow. Establishing the relative amplitude for the flow and no-flow waveforms was found necessary, particularly for noise modulated Doppler signals. Its size and accuracy, compared with other microcontroller-equipped totally implantable monitors, make it a good candidate for future tether-free free flap monitoring studies.
authors.affiliation: Department of Electrical and Computer Engineering Swanson School of Engineering University of Pittsburgh Pittsburgh PA 15261 USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Rothfuss
authors.affiliation: Department of Electrical and Computer Engineering Swanson School of Engineering University of Pittsburgh Pittsburgh PA 15261 USA.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Franconi
authors.affiliation: Department of Plastic Surgery University of Pittsburgh Pittsburgh PA 15261 USA.
authors.forename: Jignesh V
authors.initials: JV
authors.lastname: Unadkat
authors.affiliation: Department of Plastic Surgery University of Pittsburgh Pittsburgh PA 15261 USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Gimbel
authors.affiliation: Department of Chemistry University of Pittsburgh Pittsburgh PA 15260 USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Star
authors.affiliation: Department of Electrical and Computer Engineering Swanson School of Engineering University of Pittsburgh Pittsburgh PA 15261 USA.
authors.forename: Marlin H
authors.initials: MH
authors.lastname: Mickle
authors.affiliation: Department of Electrical and Computer Engineering Swanson School of Engineering University of Pittsburgh Pittsburgh PA 15261 USA.
authors.forename: Ervin
authors.initials: E
authors.lastname: Sejdic
keywords: Anastomosis; Doppler; bedside monitor; blood flow monitor; continuous wave; flowmeter; free flap