Celso Arruda

Implantable centrifugal blood pump with dual impeller and double pivot bearing system: electromechanical actuator, prototyping, and anatomical studies.

An implantable centrifugal blood pump has been developed with original features for a left ventricular assist device. This pump is part of a multicenter and international study with the objective to offer simple, affordable, and reliable devices to developing countries. Previous computational fluid dynamics investigations and wear evaluation in bearing system were performed followed by prototyping and in vitro tests. In addition, previous blood tests for assessment of normalized index of hemolysis show results of 0.0054±2.46 × 10⁻³ mg/100 L. An electromechanical actuator was tested in order to define the best motor topology and controller configuration. Three different topologies of brushless direct current motor (BLDCM) were analyzed. An electronic driver was tested in different situations, and the BLDCM had its mechanical properties tested in a dynamometer. Prior to evaluation of performance during in vivo animal studies, anatomical studies were necessary to achieve the best configuration and cannulation for left ventricular assistance. The results were considered satisfactory, and the next step is to test the performance of the device in vivo.

Introductory tests to in vivo evaluation: magnetic coupling influence in motor controller.

An implantable centrifugal blood pump has been developed with original features for a ventricle assist device (VAD). This pump is part of a multicenter and international study with objective to offer simple, affordable, and reliable devices to developing countries. Previous computational fluid dynamics investigations were performed followed by prototyping and in vitro tests. Also, previous blood tests for assessment of hemolysis showed mean normalized index of hemolysis (NIH) results of 0.0054 ± 2.46 × 10−3 mg/100 L (at 5 L/min and 100 mm Hg). To precede in vivo evaluation, measurements of magnetic coupling interference and enhancements of actuator control were necessary. Methodology was based on the study of two different work situations (1 and 2) studied with two different types of motors (A and B). Situation 1 is when the rotor of pump is closest to the motor and situation 2 its opposite. Torque and mechanical power were collected with a dynamometer (80 g/cm) and then plotted and compared for two situations and both motors. The results showed that motor A has better mechanical behavior and less influence of coupling. Results for situation 1 showed that it is more often under magnetic coupling influence than situation 2. The studies lead to the conclusion that motor A is the best option for in vivo studies as it has less influence of magnetic coupling in both situations.

Mortality rate in children caused by traffic accidents according to geographical regions : Brazil, 1997 - 2005

Fatal injuries in children caused by motor vehicle accidents represent a common situation in many countries worldwide. The present study addresses the mortality rate in children as vehicle passengers in Brazil, from 1997 to 2005. To evaluate mortality rates, the number of deaths was collected from the National Mortality Information System (SIM) and the population size was obtained using the Brazilian Bureau Census (IBGE) data available at DATASUS. Mortality rates were estimated in three-year periods and analyzed according to age groups (younger than 1 year old, 1-4 years old, 5-9 years old) and geographical regions using a 95% confidence interval. Overall results showed mortality rates of 5.68, 7.32 and 6.78 (per 1,000,000) for the 1997-1999, 2000-2002 and 2003-2005 periods, respectively for the whole country. Children younger than 1 year old had a mortality rate of 10.18 (per 1,000,000), which was higher than for the other age groups. For the period analyzed, the highest rates were observed for the Mid-West and South regions of Brazil, with rates of 13.88 and 11.47 (per 1,000,000), respectively. These results show the risk of fatal injury in children caused by motor vehicle accidents and may contribute to the establishment of educational campaigns aiming injury prevention in children as vehicle passengers.

Design, Manufacturing and Tests of an Implantable Centrifugal Blood Pump

An implantable centrifugal blood pump was developed for long-term ventricular assistance in cardiac patients. In vitro tests were performed, as wear evaluation, performance tests and hemolysis tests in human blood. Numerical computational simulations were performed during design process in order to predict its best geometry. Wear evaluations helped to select the best materials for double pivot bearing system proposed to achieve longer durability. Performance tests pointed the best impeller geometry. The implantable centrifugal blood pump was compared with other blood pumps founded in literature. The proposed implantable centrifugal blood pump showed the best performance. But, its results showed a strong descendant curve in high flow. Other prototype was manufactured with a different inlet port angle to overcome this problem. The normalized index of hemolysis (NIH) measured 0.0054 mg/100L that can be considered excellent since it is close to the minimum found in literature (between 0.004 g/ 100L e 0.02 g/ 100L). The authors’ expectation is that this pump will become a promising Technological Innovation for Sustainability.