Processing of Autonomic Signals During Gastrointestinal Stimulation in Human Subjects

Abstract

<P>Gastro-intestinal stimulation using a rectal balloon distended with an inflation device is often used to investigate patients with Irritable Bowel Syndrome (IBS). The acquisition and processing of hemodynamic signals from healthy controls and IBS patients during colo-rectal distension is explored in this thesis. Rectal stimulation was performed using a barostat system run on a labview platform. The rectal pressure (using balloon) increased gradually to a user controlled maximum value, held at a 50% discomfort level, followed by a phasic drop in pressure. A baseline and recovery period was used before inflation after deflation states respectively. The blood pressure and heart rate signals were recorded and beat-to-beat variations of these signals were computed. The autonomic signals embedded in the beat -to-beat variations of the hemodynamic variables subjected to power spectral analysis, Wigner-Ville analysis and to the computation of the baroreceptor sensitivity. The objective of the study was to develop signal processing methods to evaluate the autonomic nervous system. Results show that rectal balloon distention perturbs the human ANS and is a powerful tool into assessing the nature of the ANS response in human subjects. Novel methods of studying heart rate and blood pressure using empirical mode decomposition are also proposed.</P>