Luminal cross-sectional area and wall distensibility in the isolated porcine oesophagus.

Previous studies have demonstrated regional differences in pressure-cross-sectional area relations, compliance and tension-strain relations of the oesophagus in vivo. The measurements and the variation in axial direction may reflect not only intrinsic oesophageal properties but can also be influenced by the adjacent organs. Four pigs were thoracotomised and the oesophagus was isolated from adjacent organs. The isolated oesophagus was investigated in situ by means of impedance planimetric measurements of cross-sectional area during pressure-controlled balloon distension 5, 15, and 25cm proximal to the gastro-oesophageal junction. CSA increased in a nonlinear way as function of pressure at all recording sites. The CSAs at pressures above 20 cmH2O increased progressively in distal direction (p < 0.001). The CSAs at a physiological pressure level of 30 cmH2O were 197 +/- 10, 222 +/- 19, and 231 +/- 17 mm2 at 25, 15, and 5cm above the gastro-oesophageal junction, respectively. The cross-sectional area distensibility increased from the proximal to the distal recording site in the whole pressure range (p < 0.001) with the most pronounced difference in the low pressure range. In conclusion, the regional variation in passive distensibility of the porcine oesophagus is an inherent condition of the oesophageal wall. The data have significance for evaluation of oesophageal flow properties and agree with previous findings of slow bolus velocity in the distal oesophagus.