Flow pumping system for physiological waveforms

A pulsatile flow pumping system is developed to replicate flow waveforms with reasonable accuracy for experiments simulating physiological blood flows at numerous points in the body. The system divides the task of flow waveform generation between two pumps: a gear pump generates the mean component and a piston pump generates the oscillatory component. The system is driven by two programmable servo controllers. The frequency response of the system is used to characterize its operation. The system has been successfully tested in vascular flow experiments where sinusoidal, carotid, and coronary flow waveforms are replicated

Programmable physiological infusion

A programmable physiological infusion device and method are provided wherein a program source, such as a paper tape, is used to actuate an infusion pump in accordance with a desired program. The system is particularly applicable for dispensing calcium in a variety of waveforms

Development and evaluation of an impedance cardiographic system to measure cardiac output and other cardiac parameters Final progress report 1 Jul. 1969 - 31 Dec. 1970

Performance of impedance cardiograph for measuring heart rate and body fluid

NASA contributions to - Cardiovascular monitoring

NASA contributions to cardiovasular monitorin

New Frank-Starling based contractility and ventricular stiffness indices: clinically applicable alternative to Emax

2013 Summer.Includes bibliographical references.Heart disease is the #1 cause of death in the United States with congestive heart failure (CHF) being a leading component. Load induced CHF, i.e. CHF in response to chronic pressure or volume overload, may be classified either as systolic failure or diastolic failure, depending on the failure mode of the pumping chamber. To assess the severity of systolic failure, there exist clinical indices that quantify chamber contractility, namely: ejection fraction, (dP/dt), Emax (related to the rate of pressure rise in the pumping chamber), and Emax (related to the time-dependent elastance property of the ventricle). Unfortunately, these indices are plagued with limitations due to inherent load dependence or difficulty in clinical implementation. Indices to assess severity of diastolic failure are also limited due to load dependence. The goal of this research is to present (1) a new framework that defines a new contractility index, Tmax, and ventricular compliance 'a', based on Frank-Starling concepts that can be easily applied to human catheterization data, and (2) discusses preliminary findings in patients at various stages of valve disease. A lumped parameter model of the pumping ventricle was constructed utilizing the basic principles of the Frank-Startling law. The systemic circulation was modeled as a three element windkessel block for the arterial and venous elements. Based on the Frank-Starling curve, the new contractility index, Tmax and ventricular compliance 'a' were defined. Simulations were conducted to validate the load independence of Tmax and a computed from a novel technique based on measurements corresponding to the iso-volumetric contraction phase. Recovered Tmax and 'a' depicted load independence and deviated only a few % points from their true values. The new technique was implemented to establish the baseline Tmax and 'a' in normal human subjects from a retrospective meta-data analysis of published cardiac catheterization data. In addition, Tmax and 'a' was quantified in 12 patients with a prognosis of a mix of systolic and diastolic ventricular failure. Statistical analysis showed that Tmax was significantly different between the normal subjects group and systolic failure group (p<0.019) which implies that a decrease in Tmax indeed predicts impending systolic dysfunction. Analysis of human data also shows that the ventricular compliance index 'a' is significantly different between the normal subjects and concentric hypertrophy (p < 0.001). This research has presented a novel technique to recover load independent measures of contractility and ventricular compliance from standard cardiac catheterization data

Wave propagation in flexible tubes

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Wave dissipation was previously investigated intensively in the frequency domain, in which the dissipation of waves is described as attenuation of pressure pulse decay with respect to the frequency or harmonics. In this thesis, wave dissipation, including decay of pressure pulse, peak of wave intensity and wave energy, is investigated in the time domain using wave intensity analysis (WIA). Wave intensity analysis benefits to this research in several aspects including: 1) WIA allows for wave dissipation investigated in the time domain; 2) WIA does not make any assumptions about the tube's wall non-linearity and the analysis takes into account the effects of the vessel's wall viscoelastic properties, convective, frictional effects and fluid viscosity; 3) WIA offers a technique (separation) to study wave dissipation in one direction whilst taking into account the effect of reflections from the opposite direction; 4) The physical meaning of wave intensity provides a convenient method to study the dissipation of energy carried by the waves along flexible tubes. In this research, it is found that the degree of dissipation in flexible tube were not only affected by the mechanical properties of the wall property and viscosity of liquid but also by the other factors including initial pressure and pumping speed of piston as well as direction of wave in relation to direction of flow. Also an new technique to separate waves into forward and backward directions only using diameter and velocity might potentially be used to separate the waves in both directions non-invasively based on the non-invasive measurement of diameter (wall movement) available

A Real-Time Programmable Pulsatile Flow Pump for In-Vitro Cardiovascular Experimentation

Benchtop In-vitro experiments are valuable tools for investigating the cardiovascular system and testing medical devices. Accurate reproduction of physiologic flow waveforms at various anatomic locations is an important component of these experimental methods. This study discusses the design, construction and testing of a low-cost and fully programmable pulsatile flow pump capable of continuously producing unlimited cycles of physiologic waveforms. Two prototypes with different designs were tested. The first one consisted of a stepper motor – piston pump combination and tests showed that it failed to satisfy the design requirements. The second, highly successful prototype consists of a gear pump actuated by an AC servo-motor and a feedback algorithm enabling high accuracy for flow rates up to 300ml/s across a range of loading conditions. The iterative feedback algorithm uses flow error values in one iteration to modify motor control waveform for the next iteration to better match desired flow. Within 4-7 iterations of feedback, the pump replicated physiologic flow waveforms to high levels of accuracy (normalized RMS error less than 2%) under varying downstream impedances. This device is significantly more affordable (~10% of the cost) than current commercial options. Furthermore, the pump can be controlled via common scientific software packages and thus can be implemented in large automation frameworks