Indirect Flow Rate Estimation of the NEDO PI Gyro Pump for Chronic BVAD Experiments

Abstract

In totally implantable ventricular assist device systems, measuring flow rate of the pump is necessary to ensure proper operation of the pump in response to the recipient's condition or pump malfunction. To avoid problems associated with the use of flow probes, several methods for estimating flow rate of a rotary blood pump used as a ventricular assist device have been studied. In the present study, we have performed a chronic animal experiment with two NEDO PI gyro pumps as the biventricular assist device for 63 days to evaluate our estimation method by comparing the estimated flow rate with the measured one every 2 days. Up to 15 days after identification of the parameters, our estimations were accurate. Errors increased during postoperation days 20 to 30. Meanwhile, their correlation coefficient r was higher than 0.9 in all the acquired data, and estimated flow rate could simulate the profile of the measured one.

Developments in control systems for rotary left ventricular assist devices for heart failure patients: a review

“…This is crucial in designing an automatic, robust and responsive control system that effectively controls the blood flow according to the body's physiological needs and perturbations (Wakisaka et al 1997, Khalil et al 2008, Oshikawa et al 2000. Various groups have shown that such controllers are important to avoid and detect pumping states associated with abnormal flow conditions (Karantonis et al 2006, Ohuchi et al 2001, Amin et al 1997, Yuhki et al 1999, Endo et al 2001, Voigt et al 2005, Vollkron et al 2005, 2006, Fonseca et al 2008, Lee et al 2003.…”

“…They obtained an estimation error of 0.27 L min −1 and a correlation coefficient of 0.875 for flow, as well as an estimation error of 6.77 mmHg and a correlation coefficient of 0.775 for pressure. Also, Ogawa et al (2006) have conducted a single chronic animal experiment to evaluate the flow estimation method proposed by Yoshizawa et al (2002) where a mean square error of 0.80 L min −1 and a correlation coefficient of 0.964 were obtained.…”

“…Although previous studies produced acceptable results when applied to estimate the pulsatile flow and head, some of these studies have used higher order input/output system models (Yoshizawa et al 2002, Ogawa et al 2006 in which they did not study the stability of the transient response of the pump flow. Moreover, other researchers have assumed the system to be stable (Kitamura et al 2000).…”

“…Although the control algorithms reviewed in previous subsections have tackled the task of detecting and thus avoiding suction, here, in this subsection, we will review various physiological control strategies, heuristic algorithms, and combination of multiple indicators that only utilized to aid in detecting, preventing and thus managing abnormal pumping states in LVADs. Previously, various research groups have investigated the experimentation in the transition of pumping states (Amin et al 1997, Baloa et al 2000, Boston et al 2000a, 2000b, Endo et al 2001, Oshikawa et al 2000, Tanaka et al 2005, Voigt et al 2005, Vollkron et al 2004, 2005, 2006, Yuhki et al 1999, Olegario et al 2003, Ayre et al 2001. To aid in this task, invasive transducers were employed to measure the pump flow (e.g.…”

“…Vollkron et al 2004 andIijima et al 1997); however, it is highly desirable to avoid their use due to a significant reduction in system reliability and increased cost. To overcome this, research approaches have thus concentrated on the waveform analysis of the sensorless pump motor feedback signals including current or rotational speed from which a vital heuristic indicators of abnormal pumping states have been derived (Baloa et al 2000, Boston et al 2000b, Endo et al 2001, Oshikawa et al 2000, Tanaka et al 2005, Voigt et al 2005, Vollkron et al 2002, 2006, Yuhki et al 1999, Nakata et al 2000a, 2000b, Takami et al 1997.…”