Methods of analysing rhythmic electrical potentials in the gastrointestinal tract

The clear visual evidence of regular oscillations in electrical potentials recorded from many parts of the gut has prompted attempts to measure the frequency of these ‘slow waves’ accurately. It is desirable to replace manual measurement of such frequencies by automated methods in order to remove the tedium and time involved. A more important reason for automated methods, however, is to enable precise objective values to be given to measurements which will facilitate discussion between research groups involved in this work. Manual or automatic methods of counting a number of cycles per unit time do not give good accuracy, and are not included in this paper. Similarly the use of narrow pass-band analogue or digital filters as an indication of the presence of rhythms is also not discussed. In the context of medical electrical recording the presence of large amounts of artifacts, particularly at the lower frequency spectrum near to the ‘slow wave’ frequency band, gives problems in the use of narrow pass-band filters.