title: Noninvasive average flow estimation for an implantable rotary blood pump: a new algorithm incorporating the role of blood viscosity.
abstract: The effect of blood hematocrit (HCT) on a noninvasive flow estimation algorithm was examined in a centrifugal implantable rotary blood pump (iRBP) used for ventricular assistance. An average flow estimator, based on three parameters, input electrical power, pump speed, and HCT, was developed. Data were collected in a mock loop under steady flow conditions for a variety of pump operating points and for various HCT levels. Analysis was performed using three-dimensional polynomial surfaces to fit the collected data for each different HCT level. The polynomial coefficients of the surfaces were then analyzed as a function of HCT. Linear correlations between estimated and measured pump flow over a flow range from 1.0 to 7.5 L/min resulted in a slope of 1.024 L/min (R2=0.9805). Early patient data tested against the estimator have shown promising consistency, suggesting that consideration of HCT can improve the accuracy of existing flow estimation algorithms.
authors.affiliation: Graduate School of Biomedical Engineering, University of New South Wales (NSW), Sydney, and Alfred Hospital, Prahran, Victoria, Australia.
authors.forename: Nicolò
authors.initials: N
authors.lastname: Malagutti
authors.forename: Dean M
authors.initials: DM
authors.lastname: Karantonis
authors.forename: Shaun L
authors.initials: SL
authors.lastname: Cloherty
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Ayre
authors.forename: David G
authors.initials: DG
authors.lastname: Mason
authors.forename: Robert F
authors.initials: RF
authors.lastname: Salamonsen
authors.forename: Nigel H
authors.initials: NH
authors.lastname: Lovell
mesh_terms: D000465:Algorithms; D001783:Blood Flow Velocity; D001809:Blood Viscosity / Q000502:physiology*; D004867:Equipment Design; D006353:Heart-Assist Devices; D006400:Hematocrit; D006801:Humans; D008422:Materials Testing; D008955:Models, Cardiovascular; D019736:Prostheses and Implants; D012212:Rheology / Q000295:instrumentation; D018487:Ventricular Dysfunction, Left / Q000628:therapy