Synchronous recording and review of oesophageal manometry and video fluoroscopy using a portable manometry recorder and PC with integrated digital video acquisition

Temporal relationships between wall motion, intraluminal pressure, and flow in the isolated rabbit small intestine

Intraluminal manometry is a tool commonly used to record motility in the human digestive tract. The recorded signal results from a combination of factors, including the hydrodynamic pressure transmitted through the intestinal contents due to contraction of the gut wall and the force of the gut wall acting on the sensors in regions of a luminal occlusion. However, the actual relationships between small bowel wall contraction, the measured intraluminal pressure, and the resultant flow have not been directly addressed. Video recording and high-resolution fiber-optic manometry were used to create spatiotemporal video maps of diameter and intraluminal pressure from isolated segments of rabbit small intestine. In the unstimulated gut, longitudinal muscle contractions were the only detectable motor pattern; circular muscle contractions were elicited by distension or erythromycin (1 μM). Longitudinal muscle contractions were not lumen-occlusive, although they caused measurable low-amplitude changes in pressure. Localized nonpropagating circular muscle contractions caused small localized, nonpropagating peaks of intraluminal pressure. Propagating contractions of circular muscle evoked larger, propagating pressure changes that were associated with outflow. Propagating circular muscle contractions often caused dilation of aboral receiving segments, corresponding to "common cavities"; these were propulsive, despite their low intraluminal pressure. The highest-amplitude pressure events were caused by lumen-occlusive circular muscle contractions that squeezed directly against the catheter. These data allow us to define the complex relationships between wall motion, intraluminal pressure, and flow. A strong correlation between circular and longitudinal muscle contraction and intraluminal pressure was demonstrated. Common-cavity pressure events, caused by propulsion of content by circular muscle contractions into a receptive segment, were often of low amplitude but were highly propulsive. Studies of wall motion in isolated preparations, combined with manometry, can assist in interpretation of pressure recordings in vivo.

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

OBJECTIVE

Artificial neural networks (ANNs) can rapidly analyse large data sets and exploit complex mathematical relationships between variables. We investigated the feasibility of utilizing ANNs in the recognition and objective classification of primary oesophageal motor disorders, based on stationary oesophageal manometry recordings.

MATERIAL AND METHODS

One hundred swallow sequences, including 80 that were representative of various oesophageal motor disorders and 20 of normal motility, were identified from 54 patients (34 F; median age 59 years). Two different ANN techniques were trained to recognize normal and abnormal swallow sequences using mathematical features of pressure wave patterns both with (ANN(+)) and without (ANN(-)) the inclusion of standard manometric criteria. The ANNs were cross-validated and their performances were compared to the diagnoses obtained by standard visual evaluation of the manometric data.

RESULTS

Interestingly, ANN(-), rather than ANN(+), programs gave the best overall performance, correctly classifying >80% of swallow sequences (achalasia 100%, nutcracker oesophagus 100%, ineffective oesophageal motility 80%, diffuse oesophageal spasm 60%, normal motility 80%). The standard deviation of the distal oesophageal pressure and propagated pressure wave activity were the most influential variables in the ANN(-) and ANN(+) programs, respectively.

CONCLUSIONS

ANNs represent a potentially important tool that can be used to improve the classification and diagnosis of primary oesophageal motility disorders.

A pH-mucosa area unit of measure to consider morphology of the oesophagus when evaluating oesophagitis

Gastro-oesophageal pH measurements are routinely carried out to quantify and determine if levels of acid reflux are responsible for symptoms. Although considered the 'gold standard', evidence suggests that pH measurements do not correlate well with the degree of oesophagitis seen during endoscopy. In this study the current measure of pH was critically examined taking into account both the effects of changes in luminal diameter and endoscopy observations. The oesophageal lumen diameter was investigated using a barium swallow for 25 patients presenting with oesophageal disorders. For each subject the widest luminal diameter was measured for a series of five controlled swallows. The results showed that the lumen diameter varied widely from 0.9 to 3.8 cm. An alternative approach to the current measurement of pH was explored. In this approach the exposure not only included the luminal pH and time exposed but also the area of mucosa exposed as a result of differing luminal diameters. Although it is currently not possible to assess the diameter or morphology of the oesophageal lumen during a pH study, the analysis highlighted that the current measure of pH exposure time does not include the area of mucosa exposed. These results may explain, to some extent, the poor correlation between pH measurements and degree of oesophagitis seen during endoscopy.

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

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.

Technical report: The introduction of a new synchronized oesophageal manometry and digital video-fluoroscopy (fluoromanometry) system into the radiology suite

Following the development of a new fluoromanometry system enabling synchronous oesophageal manometry and barium swallow video-fluoroscopy, both the equipment and examination method have been successfully introduced into the radiology suite. The application of the system which uses a PC with video capture and a portable manometry recorder is described together with details of its implementation and the examination technique used.