A new distensibility technique to measure sphincter of Oddi function.

BACKGROUND: Evaluation of the biliary tract is important in physiological, pathophysiological, and clinical studies. Although the sphincter of Oddi (SO) can be evaluated with manometry, this technique has several limitations. This may explain the difficulties in identifying pathophysiological mechanisms for dysfunction of the SO and in identifying patients who may benefit from certain therapies. To encompass problems with manometry, methods such as the functional lumen imaging probe (FLIP) technique have been developed to study GI sphincters. This study set about miniaturising the FLIP probe and validating it for measurements in the SO. In order to get a better physiological understanding of the SO the aims were to show the sphincter profile in vivo and motility patterns of SO in pilot studies using volunteers that were experiencing biliary type pain but had normal SO manometry. METHODS: The SO probe was constructed to measure eight cross-sectional areas (CSA) along a length of 25 mm inside a saline-filled bag. To validate the technique for profiling the SO, six perspex cylinders with different CSAs were measured nine times to assess reproducibility and accuracy. KEY RESULTS: Reproducibility and accuracy for these measurements were good. The probe performed well in bench tests and was therefore tested in four humans. The data indicated that it was possible to make distensions in the human SO and that a geometric sphincter profile could be obtained. CONCLUSIONS & INFERENCES: The probe will in future studies be tested for diagnostic purposes related to sphincter of Oddi diseases.

Reproducibility of axial force and manometric recordings in the oesophagus during wet and dry swallows.

BACKGROUND: Manometry is the golden standard to diagnose oesophageal motility disorders but it gives an indirect picture of the peristalsis by measuring radial force only. A novel probe design using electrical impedance recordings enabled axial force and manometry to be recorded simultaneously. Using this method the aims were to study the amplitude and duration of peristaltic contractions, to test the correlation between axial force and manometry, and the reproducibility of the method. METHODS: Ten healthy men were included twice. The probe was positioned 5 cm proximal to the lower oesophageal sphincter after which five dry swallows and five wet swallows were done. This was repeated with 0, 2, 4 and 6 mL of water in a bag mounted distal to the axial force recording site. KEY RESULTS: Duration and amplitude of contractions were measured by axial force and manometry. Both increased with the bag volume (P < 0.05), with force measurements having approximately twice the dynamic range than manometry (P < 0.05). Contraction duration and amplitude showed good reproducibility for both axial force and manometry (interclass correlation coefficients >0.6). The best association between axial force and manometry was found during wet swallows with an empty bag (r = 0.72, P < 0.001), otherwise these measurements were not associated. CONCLUSIONS & INFERENCES: The system provided a more complete description of primary oesophageal peristalsis. Axial force and manometry were both reproducible but force measurements had increased dynamic range. As manometry and axial force generally are not associated, they each provide different information, and in combination they may be useful to better characterize oesophageal motor function.

Multimodal sensory testing of the rectum and rectosigmoid: development and reproducibility of a new method.

Evaluation of rectal and rectosigmoid sensation is important in basic, clinical and pharmacological studies. New methods to evoke and assess multimodal (electrical, thermal and mechanical) experimental pain of the upper gut activate distinct pathways and mimics clinical pain. The aims of the current study were to characterize the sensory response and reproducibility to multimodal stimulation of rectum and the rectosigmoid. A multimodal rectal probe was developed. Mucosal electrostimulation was delivered at the recto-sigmoid junction. In Rectum, impedance planimetry was used for measurement of cross-sectional area (CSA) during distension. Circulation of water within the bag at either 4 or 60 degrees C was applied for thermal stimulation. The method was tested in 12 healthy volunteers (six men mean age 32 years) on two subsequent days. Mechanical and sensory responses and referred pain areas were assessed. Stimulation with electrical, thermal and mechanical modalities resulted in different sensory perceptions. The relationship between stimulus intensity and sensory response was linear for all modalities. Sensory response to different modalities did not differ between investigation days (all P-values > 0.1). Approximately 75% of subjects felt referred pain in distinct skin locations. Between-days reproducibility was good for all modalities [intra-class correlation (ICC) > or = 0.6]. At sensory threshold, CSA showed best reproducibility (ICC > or = 0.9). At pain detection threshold stretch ratio, CSA and electrostimulation showed best reproducibility (ICC = 1.0; 0.9; 0.9). The present model was easily implemented, robust and showed good reproducibility. It can be used to study pathophysiology or pharmacological interventions in healthy controls and in patients with diseases involving the distal hindgut.

Measurement of the axial force during primary peristalsis in the oesophagus using a novel electrical impedance technology.

The oesophagus serves to transport food and fluid from the pharynx to the stomach. Oesophageal function is usually evaluated by means of manometry which is a proxy of the force in the radial direction. However, force measurements in the axial direction will provide a better measure of oesophageal transport function. The aim of this study was to develop a probe based on electrical impedance measurements to quantify the axial force generated by oesophageal contractions, i.e. probe elongation was associated with the axial force. Calibration with weights up to 200 g was done. The dispersion, creep, temperature and bending dependence were studied at the bench. Subsequently, the probe was tested in vivo in a healthy human volunteer. The probe showed good reproducibility and the dispersion was <0.04. Some dependence on temperature, creep and bending was found. Interpolation of the calibration curves made it possible to compensate for temperature fluctuations. The maximum deviation was 6.1 +/- 3.7% at loads of 50 g. The influence of creep showed a maximum net creep of 6.1 g after 8 s. The swallowed bolus size correlated with the axial force measurements (P = 0.038) but not with manometric measurements. In conclusion, the new technique measures axial force in the oesophagus and may in the future provide valuable information about oesophageal function.