Biomechanical Wall Properties of the Porcine Rectum: A Study Using Impedance Planimetry

Abstract

The aim was to investigate biomechanical wall properties of the porcine rectum by way of manometry and impedance planimetry. Distension of a balloon inserted into the rectum with definite pressure steps up to 80 cm H₂0 was done for simultaneous recording of pressure and the balloon cross-sectional area (Bcsa). Viscoelastic wall properties were derived in terms of compliance. Besides eliciting the ascending peristaltic reflex and relaxation of the internal anal sphincter, the balloon inflation elicited a phase of rapid Bcsa increase followed by an accommodation phase of slow Bcsa increase to a steady-state Bcsa, reached within 3 min. The Bcsa increased in a nonlinear way with increasing balloon pressures with only a minimal increase from 70 to 80 cm H₂O. Rectal compliance decreased in a nonlinear way with increasing distension pressure.

New probe for the measurement of dynamic changes in the rectum

“…Interindividual variations in luminal dimensions were considerable. A variation in CSA has previously been reported in pigs 12 and humans studied by using impedance planimetry 10 or the barostat 17 …”

“…Colstrup et al 4 covered the measuring electrodes with a balloon to overcome the problem of variable conductivity. This method has been used to assess biomechanical properties in the oesophagus, 5–7 duodenum, 8,9 and the rectum 10–12 …”

“…This method has been used to assess biomechanical properties in the oesophagus, 5-7 duodenum, 8,9 and the rectum. [10][11][12] The overall objective of this study was to simultaneously assess circumferential dimensions at several positions within the rectum with a new impedance probe. The specific aims of the study were to: (i) design a probe with several sets of detection electrodes for multiple cross-sectional area (CSA) measurements, (ii) describe the properties of the probe in vitro and (iii) describe CSA of the porcine rectum at several levels simultaneously, i.e.…”

Incremental elastic modulus - a challenge to compliance

“…Simultaneous measurement of pressure and radius is now possible using impedance planimetry [13][14][15][16][17][18][19]. This technique needs further evaluation prior to its acceptance in routine anorectal physiology.…”

Versatile Software System for Analysis of Gastrointestinal Pressure Recordings

“…The program has been applied on pres sure recordings from the stomach, duode num, and for more special purposes such as modality analysis of rectal pressure activity and radial analysis of duodenal pressure re cordings [1,5,6,9,10]. Furthermore, it is a platform for further development, such as a special algorithm for elimination of artifacts in the pressure recordings.…”