An investigation into the spatial relationship between complexity and motility within the oesophagus

Abstract

Nonlinear analysis techniques have recently been used in the characterization of complex physiological signals seen in pathological disorders such as epilepsy and cardiac fibrillation. In this study a series of controlled swallows from an asymptomatic demonstration group was investigated using oesophageal manometry. The nonlinear measure of complexity, largest Lyapunov exponents and phase portraits were then used to explore the complexity of motility patterns at different points within the oesophagus. Results indicate greater complexity within the region of the striated muscle in the upper oesophagus than that observed within the region of smooth muscle in the lower oesophagus. Phase portraits showed that manometry patterns within the asymptomatic demonstration group could be quite different, highlighting the problems in clinical diagnosis. The characterization of motility disorders associated with complex manometry patterns such as diffuse oesophageal spasm (DOS) and nonspecific motility disorder (NOMD) still represents a diagnostic challenge. The use of nonlinear techniques enabling the quantitative and qualitative measurement of oesophageal complexity is considered in the classification of such disorders.

Evaluation of artificial neural networks in the classification of primary oesophageal dysmotility

“…In further studies more advanced approaches to signal processing and computer programming could be applied; for example automated pre-processing packages [26,27], cubic B-splines [28] or largest Lyapunov exponents [10]. In addition, ''unsupervised'' ANNs, i.e.…”

“…Haylett et al [10] used non-linear chaos theory to assess and quantify oesophageal motor dysfunction; it was concluded that for the classification of oesophageal motor disorders, especially DOS and non-specific oesophageal motility disorders, such non-linear techniques may be superior to conventional techniques. Artificial neural networks (ANNs) are mathematical models that use non-linear statistical analysis to elucidate previously unrecognized relationships between given input variables and an output variable [11,12].…”

Properties of Bi4Ti3O12–(Na1/2Bi1/2)TiO3Piezoelectric Ceramics

“…For example, our previous work examining the nonlinear nature of oesophageal peristalsis has highlighted that the complexity of oesophageal peristalsis varies widely between asymptomatic subjects (Haylett et al 1998). The analyses of these multidimensional data represent a major challenge.…”

Using Kohonen self organising feature maps for the analysis of ambulatory oesophageal manometry

“…The events were analysed for the pressures recorded at the 2 nd transducer, midway in the smooth muscle of the oesophagus. Measurements of pressure above this point may be more complex as a result of the initialisation of the swallow and impact of striated muscle [5]. Measurements below this point towards the distal oesophagus may have additional complexity as a result of the sphincter between the oesophagus and stomach.…”