The use of on-line telephonic computer analysis of the E.E.G. in anaesthesia

Abstract

Clinical application of electroencephalographic monitoring has generally been restricted by the complexity of on-line unprocessed data analysis. A technique has been developed which expands the applicability of clinical e.e.g. monitoring and presents the clinician with an e.e.g. spectral analysis designed specifically for readability in a dynamic environment. In this technique, one or more channels of electroencephalographic data are amplified, frequency-modulated and transmitted over a standard unprocessed, voice grade, direct distance dialling telephone line to a PDP-12 computer (8k memory). This information is processed in 4- or 8-second blocks using fast Fourier transform methods to present a power spectral plot of 0-16 Hertz bandwidth. Successive blocks of data are analysed similarly and plotted by computer direction to give a continuous record of the e.e.g. spectrum. These spectrum plots are simultaneously retransmitted over the same telephone line to the e.e.g. transmission location and plotted on a Y-T recorder. This system is currently being used in the operating room to guide the induction of safe, effective anaesthesia and ensure the adequacy of cerebral oxygenation. © 1973 John Sherratt and Son Ltd.