Is the absorption of anaesthetic agents non linear?

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dc.contributor.advisor Hugo, Johan M. en
dc.contributor.postgraduate Steyn, Johan Daniel en
dc.date.accessioned 2013-09-07T12:45:21Z
dc.date.available 2005-09-22 en
dc.date.available 2013-09-07T12:45:21Z
dc.date.created 2003-09-01 en
dc.date.issued 2005-09-22 en
dc.date.submitted 2005-09-19 en
dc.description Thesis (PhD (Anaesthesiology))--University of Pretoria, 2005. en
dc.description.abstract Knowledge of the absorption of inhalation anaesthetic agents is essential if one is to safely administer them. Despite many years of research in linear science, no model has been described that can reliably predict inhalation agent uptake. To date no published investigation has looked for non¬linearity in the absorption process. The aim if this research project was to determine if the absorption of anaesthetic agents is non-linear, using isoflurane and enflurane as examples. To detect non-linearity, four conditions must be met: <ul> <li>Sensitivity to initial conditions, </li> <li>Fractal Dimension of the attract or, </li> <li>Invariant probability distribution of the attractor, and</li> <li>Detection of an underlying dynamical process. <br></li></ul> Ten measured time series for both isoflurane and enflurane absorption were measured. These were then compared with ten noise signals, with similar standard deviations, means and number of points in the series. Calculated Lyapunov exponents tested sensitivity to initial conditions. The dimension of the attractor was calculated using the following statistics, each giving an approximation of the fractal dimension. Approximate entropy, information entropy, correlation dimension and fractal dimension (box counting method). The Invariant probability distribution of the attractor was tested for using non-linear forecasting. Detection of an underlying dynamical process was determined by the method of surrogate data. Each of the four conditions required have been met with statistical significance ( p< 0.05) and acceptable statistical power (>0.8). It is therefore concluded that the absorption of both isoflurane and enflurane are non-linear processes. The implications and implementations in anaesthesia practice are discussed. en
dc.description.availability unrestricted en
dc.description.department Anaesthesiology en
dc.identifier.citation Steyn, JD 2003, I the absorption of anaesthetic agents non linear?, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/28033 > en
dc.identifier.other H1049/ag en
dc.identifier.upetdurl http://upetd.up.ac.za/thesis/available/etd-09192005-161652/ en
dc.identifier.uri http://hdl.handle.net/2263/28033
dc.language.iso en
dc.publisher University of Pretoria en_ZA
dc.rights © 2003 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. en
dc.subject Isoflurane en
dc.subject Enflurane en
dc.subject Anaesthesia en
dc.subject Anaesthetics en
dc.subject Absorption physiology en
dc.subject UCTD en_US
dc.title Is the absorption of anaesthetic agents non linear? en
dc.type Thesis en


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