Ph D Thesis Amelie Deglaire - TEL

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A T-cannula is inserted into the intact ileum and a second cannula is inserted into the
caecum. The cannulae are exteriorized and connected with plastic tubing, which is
removed for digesta collection. Digesta can then be collected quantitatively, thus
avoiding the need for a dietary marker. However, this technique has two major
disadvantages: (1) intestinal motility alteration because of the complete transection of the
terminal ileum; (2) frequent blockages, when the cannula is in the re-entrant position, for
diets that are not finely ground.
A modification of the original re-entrant cannula has been proposed (Darcy et al., 1980),
such that the cannula is located immediately distal to the ileo-caecal valve. However, the
surgery is traumatic and blockages still occur. Nowadays, this method is used
infrequently.
PVTC cannula
Post-valve T-caecum (PVTC) cannulation (Figure 4) involves the removal of
approximately two-thirds of the caecum, with the insertion of the cannula into the
remaining caecum, opposite to the ileo-caecal valve (van Leeuwen et al., 1991).
Abdominal
wall
ileum
Ileo-caecal valve
colon
ileum
colon
With the cannula bung. After removal of the cannula bung.
Ileo-caecal valve
Figure 4. Post-valve T-caecum (PVTC) cannula used in pigs for ileal digesta collection.
Adapted from van Leeuwen et al. (1991).
When the cannula bung is removed, the difference between the intestinal pressure and
atmospheric pressure causes the ileo-caecal valve to protrude into the cannula lumen. The
major advantage of this technique, above other cannulation methods, is that the small
intestine is left intact. Also, if the bore of the cannula is sufficiently large, most blockages
can be avoided, thus allowing the use of any diet (Hodgkinson & Moughan, 2000).
Dietary marker (Cr2O3) recovery has been reported to range between 72 and 106%