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Biomedical subjects

V C Rideout

Publications and source records attributed to V C Rideout.

11 recordsLinked to original sources
PubMed1991

A first course in computer-aided physiological modeling.

Early experiences at Wisconsin with analog and analog-hybrid modeling of physiological systems (particularly cardiovascular systems) were successful in arousing student interest and led to later applications of modeling in research work by these students. Beginning in the early '80s, all-digital modeling was used in the senior-grad course ECE 620, using the ACSL language, and applications were included in compartment modeling of pharmacokinetics, modeling of cardiovascular and respiratory pressure-flow and transport, thermoregulation, and prosthetic systems. In this course initial model programs of some complexity (up to 30 differential equations, some of them nonlinear) were provided to the students so that they could easily begin to work with models of meaningful size. The use of module and "multiple model" schemes appear to make this approach successful, and extension to more advanced models is possible.

Computer Simulation↗
PubMed1987

Automatic control of anesthesia using two feedback variables.

A new controller of an ON/OFF type was implemented for halothane anesthesia. A proportional-plus-integral controller with time-delay compensation proved not to be robust enough for the known clinical situation, as shown both in computer simulations and in animal trials. The ON/OFF controller proved to be less sensitive to parameter mismatches, and repeated animal trials showed a short response time and acceptable steady-state tracking. A method for switching the controlled effect of the drug was also developed, since anesthetic agents have multiple effects. Mean arterial blood pressure and a measure of EEG frequency were chosen as controlled variables, both being depressed by halothane. A coordinator forces the system state as near the desired values of these variables as possible, given that only one drug is used.

Algorithms↗
PubMed1982

Simulation analysis of interatrial transposition of venous return (Mustard's operation).

Transposition of the great arteries is functionally corrected by Mustard's operation, an operation in which the atrial septum is removed and the resulting common atrial chamber repartitioned by a baffle to transpose venous return to the heart. To better understand the new physiology, a physically-based mathematical model of the infant circulation following Mustard's operation was developed and studied with the aid of computer simulation. The model reproduces certain clinical observations, including the tendency for mean pressure in both atria to be equal early postoperatively and for the pressure waveform to exhibit a steep y-descent in the systemic venous atrium. Simulation studies suggest that the mechanism for the former is transbaffle pressure coupling resulting from dynamic motion of the baffle; the mechanism for the latter is limitation of the extent of such baffle excursions. Dynamic volume of the two atria is found in the model to change according to the relative performance of the two ventricles, and stiffening the baffle leads to pressure waveforms characteristic of a small, noncompliant atrium. Mechanisms for venous "obstruction" and decompression were also studied. The baffle and its movements, however, have little effect upon cardiac output in the model, leaving unexplained the clinical observation of low output early postoperatively.

Blood Circulation↗