Biomedical subjects
Publications and source records attributed to W Welkowitz.
Varicose veins and venous ailments are common among adult Americans. Treatment procedures vary but are mostly invasive. The current investigation utilizes focused high-intensity ultrasound for producing destruction of the venous wall in experimental dogs and in patients with varicose veins. Results are encouraging and suggest that focused ultrasonic irradiation can be an efficacious means of treating varicose veins and other venous disorders.
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This paper studies the problem of identification of suitable biological variables for optimal effectiveness of a CAD. To identify suitable error signals, a closed loop simulation and analysis of the assisted circulation was carried out. Results show that the combination of heart rate and left atrial pressure is very effective as an input error signal for either series or parallel assisted circulation when simulated heart failure is severe (greater than 50% decrease in left ventricular elastance). During simulated exercise (50% reduction in peripheral resistance) such a combination is even more effective. In addition, simulation results show that aortic pressure and cardiac output are not suitable control variables for CAD.
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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.
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