Search PubMed⌕ Search

Biomedical subjects

B G Min

Publications and source records attributed to B G Min.

At least 55 records · Page 3Linked to original sources
PubMed1991

Development of a new moving-actuator type electromechanical total artificial heart.

A new type of electromechanical total artificial heart based on a moving-actuator mechanism was developed to decrease the total pump size and to improve the fitting characteristic of the pump to atrial remnants and arterial vessels. The blood pump consists of three major parts: right and left blood sacs and a moving pump actuator between two sacs. The total weight is 810 g and the volume of the pump is 770 ml. The actuator rolls back and forth on a circular track, producing alternating blood ejection. The pump performance was evaluated in mock circulation and animal implant experiments. The pump was implanted for 100 h in a calf (approximately 100 kg) with a stable hemodynamic state until accidental (electrical short circuit) death.

Animals↗
PubMed1990

A moving-actuator type electromechanical total artificial heart--Part I: Linear type and mock circulation experiments.

A new type of motor-driven total artificial heart system with a moving-actuator mechanism has been developed. The prototype system consists of a brushless dc motor inside of a rolling-cylinder, two arc-shaped pusher-plates and two polyurethane sacs. The moving-actuator type electromechanical pump has structural advantages of small size and light weight, as compared to other reported motor-driven pumps with fixed-actuator mechanisms. The results of the mock circulation tests are reported in this paper with a cardiac output of 9 L/min at an aortic pressure of 120 mmHg and a heart rate of 120 bpm. The fulfillment of the basic control requirements of the artificial heart was also confirmed, i.e., preload sensitive and afterload insensitive cardiac output response and balanced right and left ventricular outputs.

Algorithms↗
PubMed1990

A moving-actuator type electromechanical total artificial heart--Part II: Circular type and animal experiment.

A new type of electromechanical total artificial heart (TAH) based on circular rolling-cylinder mechanism was developed to overcome critical problems in motor-driven artificial hearts such as large size and difficulties in fitting the heart to atrial remnants and arterial vessels. Its performance and reliability were evaluated in mock circulation and in an animal implant experiment. The total weight and volume of the pump is 650 g and 600 mL, respectively. This new pump was implanted in a calf for total heart replacement and 96 h of survival was achieved. The whole system, including pump, controller, and control algorithm performed well enough to improve the prospect of eventual clinical application of our TAH system.

Animals↗
PubMed1985

Separation of physiological factors influencing glucose-insulin kinetics in diabetic patients.

A new quantitative method was developed for separation of physiological factors influencing glucose intolerance in diabetes mellitus using a three-compartmental model and the intravenous glucose tolerance test (IVGTT) in humans. The present model includes the physiologic factors of the hepatic glucose balance function, the peripheral tissue's glucose utilization rate, and the insulin secretion rate. The insulin sensitivity parameter and hepatic glucose sensitivity parameter were estimated in optimal fitting of the model-based data of glucose and insulin concentrations to the measured IVGTT data in 9 normal and 11 diabetic subjects. The results show that these sensitivity parameters are important for separation of the effects of the interactive physiologic factors, and, also useful in evaluating different glucose-insulin kinetics in 3 clinical groups of normal and diabetic subjects.

Adult↗
PubMed1983

Estimation of respiratory impedance and source pressure using a Thévenin equivalent circuit model.

The objective of this paper is to present a new technique which can provide both active respiration source pressure and lung impedance in a single noninvasive test. The method is based upon a Thévenin equivalent circuit model of respiratory mechanics. Using this model, the equivalent source pressure and source impedance can be computed from the measured changes of respiratory pressures and flows in two consecutive cycles before and after addition of purely resistive loads to the mouth. In maximal breathing the source parameters were reproducible in six normal human subjects. The total respiratory resistance during maximal breathing had an average value of 3.46 cmH2O l-1 s-1, and the total dynamic compliance had an average value of 0.078 l cmH2O-1. The airway resistances measured using a plethysmographic method were within the range of 45-65% of the estimated total respiratory resistances. These two resistances were related with a correlation coefficient of 0.98. An average value of the magnitudes of the fundamental components of the source pressure was 6.73 cmH2O during maximal breathing and 2.09 cmH2O during spontaneous breathing.

Airway Resistance↗
PubMed1978

A microcomputer-based data acquisition and analysis system for CO2 rebreathing studies.

A real-time microcomputer-based data acquisition and analysis system has been developed to automate the measurement of the ventilatory response to CO2 by the rebreathing method. Previous systems acquire the data on-line and then analyze and display the results off-line. The system described here performs all processing on-line and displays experimental results in real-time. The results of 5 min of data acquisition are available for display only 1.5 sec after completion of the experiment. Immediate interpretation of the results of each experiment enable a series of related studies to be performed on the same patient in a short time period. The microcomputer is Digital Equipment Corporation's LSI-11, a low cost 16 bit machine with the basic instruction set of a PDP-11/40. The system has 16 kbytes of memory, a CRT for data display, and a paper tape reader for program loading. Due to the time constraints of real-time processing and the memory constraints of a small system, the software is written entirely in assembler language. The software includes routines for numeric and character input, line and graphical output, linear curve fitting, start of rise detection and floating point computations.

Carbon Dioxide↗