Improving the accuracy of depth of anaesthesia using modified detrended fluctuation analysis method

This paper presents a modified detrended fluctuation analysis (MDFA) to improve the monitoring accuracy of the depth of anaesthesia (DoA). We first use MDFA to classify anaesthesia state levels into awake, light, moderate, deep and very deep states. Then we build up five zones using linear regression method from very deep anaesthesia state to awake state, corresponding with different box sizes. Finally, the Lagrange method is applied to compute the DoA. Comparing with the most popular Bispectral Index (BIS) method, our modified DFA method extends the ranges of the moderate anaesthesia, deep anaesthesia and very deep anaesthesia to provide more information about the DoA. This extension is very significant in the clinical perspective as these states are within the ranges for operations and need more attention. Simulation results demonstrate that the new technique monitors the DoA in all anaesthesia states accurately. (C) 2009 Elsevier Ltd. All rights reserved.