title: Development of a flow rate monitoring method for the wearable ventricular assist device driver.
abstract: Our research institute has been working on the development of a compact wearable drive unit for an extracorporeal ventricular assist device (VAD) with a pneumatically driven pump. A method for checking the pump blood flow on the side of the drive unit without modifying the existing blood pump and impairing the portability of it will be useful. In this study, to calculate the pump flow rate indirectly from measuring the flow rate of the driving air of the VAD air chamber, we conducted experiments using a mock circuit to investigate the correlation between the air flow rate and the pump flow rate as well as its accuracy and error factors. The pump flow rate was measured using an ultrasonic flow meter at the inflow and outflow tube, and the air flow was measured using a thermal mass flow meter at the driveline. Similarity in the instantaneous waveform was confirmed between the air flow rate in the driveline and the pump flow rate. Some limitations of this technique were indicated by consideration of the error factors. A significant correlation was found between the average pump flow rate in the ejecting direction and the average air flow rate in the ejecting direction (R2 = 0.704-0.856), and the air flow rate in the filling direction (R2 = 0.947-0.971). It was demonstrated that the average pump flow rate was estimated exactly in a wide range of drive conditions using the air flow of the filling phase.
authors.affiliation: Department of Artificial Organs, National Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita-shi, Osaka, 565-8565, Japan, ohnuma.kentaro@ri.ncvc.go.jp.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Ohnuma
authors.forename: Akihiko
authors.initials: A
authors.lastname: Homma
authors.forename: Hirohito
authors.initials: H
authors.lastname: Sumikura
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tsukiya
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Takewa
authors.forename: Toshihide
authors.initials: T
authors.lastname: Mizuno
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mukaibayashi
authors.forename: Koichi
authors.initials: K
authors.lastname: Kojima
authors.forename: Kazuo
authors.initials: K
authors.lastname: Katano
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Taenaka
authors.forename: Eisuke
authors.initials: E
authors.lastname: Tatsumi
mesh_terms: D000399:Air Pressure; D001783:Blood Flow Velocity / Q000502:physiology*; D004867:Equipment Design; D045268:Flowmeters; D006353:Heart-Assist Devices; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008955:Models, Cardiovascular; D012212:Rheology / Q000379:methods*