Document Type

Thesis

Date of Award

5-31-1993

Degree Name

Master of Science in Biomedical Engineering - (M.S.)

Department

Biomedical Engineering Committee

First Advisor

Arthur B. Ritter

Second Advisor

Alex Y. Bekker

Third Advisor

David S. Kristol

Abstract

The induction of general anesthesia is associated with severe hemodynamic compromises which, in turn, may cause acute elevation of intracranial pressure (ICP). Quantitative assessment of cerebrovascular responses arising from multiple mechanical and pharmacological interventions occurring in a short time interval require a large number of human studies which are difficult to perform. The purpose of this project is to evaluate the effect of various stimuli on the intracranial hemodynamics during induction using a mathematical model of cerebrovascular circulation.

A five compartmental model of the cerebrovascular system is used for our simulation. Autoregulation is modeled by adjusting arterial-arteriolar resistance in order to change the flow towards its control value. The effect of thiopental on cerebrovascular circulation is simulated by a variable arteriolar resistance which is functionally dependent on the thiopental concentration. Thiopental concentration, in turn, is predicted by a three compartmental pharmacokinetic model. The simulation program was written in TUTSIM dynamic simulation language for an IBM compatible PC. The presented computer simulation permits development of an optimal drug administration schedule to control ICP during various phases of anesthesia. It was demonstrated that if the time interval between the administration of a drug and intubation is more than 2 minutes, an additional dose of thiopental is required to prevent elevation of ICP during laryngoscopy.

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