FBGS International NV

High-resolution manometry changes our views of gastrointestinal motility

Department of Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden

High-resolution manometry using catheters with 36
solid-state sensors spaced 1 cm apart has already
become an established technique for esophageal
manometry where it has replaced water-perfused and
station pull-through manometry. Spatiotemporal plots
with color coding of pressure have greatly facilitated
the analysis of esophageal peristalsis. Although suitable
for the length of the esophagus, the solid-state
catheter is insufficient for the study of longer segments
of the gastrointestinal tract. A new technique with
fiber-optic sensors has made it possible to construct
catheters with 72–144 sensors. Studies of colonic
motility have revealed that the most common motor
pattern of the colon is a peristaltic contraction that
travels 7–10 cm in the retrograde direction. Earlier
studies using low-resolution manometry with
7–45 cm between sensors led us to erroneous conclusions
regarding direction and frequency of contractions
and they largely missed both antegrade and
retrograde contractions traveling short distances.
Fiber-optic high-resolution manometry holds promise
for greatly improving our understanding of gut
motor physiology and hopefully also our understanding
of patients with symptoms of disordered gut

This issue of Neurogastroenterology and Motility
contains a remarkable report on the fundamentals of
high-resolution colonic manometry by Dinning et al.1
The report is remarkable because it necessitates a
paradigm shift in our views of colonic motor physiology.
Using densely spaced fiber-optic sensors, the
authors convincingly show that our previous views of
colonic motor activity were built on recordings that
had an inadequate spatial resolution of measurement
points along the colon.

The previous conclusion that stationary contractions
were the predominant motor pattern of the
colon2 was erroneous, and so was the suggestion that
propagation of pressure events was predominantly
antegrade.3 Instead, the most prevalent motor pattern
seems to be retrograde peristaltic sequences.1 The
majority of such contractions travel 7–10 cm and this
is probably the reason why they have largely remained
unnoticed by low-resolution manometry with pressure
sensors spaced 7–45 cm apart.2–4 The only pattern that
was correctly identified by low-resolution manometry
was the high-amplitude propagated contraction.

Clearly, high-resolution manometry will improve
our understanding of colonic motor physiology but it
remains to find out if this technique will also improve
our understanding of patients with colonic symptoms.
Our current techniques for investigating patients with,
for example, constipation are indeed crude and limited
to measuring colonic transit and imaging of defecation.
It will be interesting to apply the high-resolution
technique in patients with functional bowel disorders
and those with underlying systemic disorders such as
diabetes mellitus, Parkinson disease, and multiple
sclerosis. The high-resolution technique also holds
promise for aiding the development of targeted therapies
in colonic motility disorders.

Early experiments used water-perfused
micro-catheters.5 The development of solid-state catheters
made high-resolution manometry accessible for a
broader audience.6 High-resolution manometry yields
large amounts of data but advances in computer
performance made it possible to display measurements
as spatiotemporal graphs with iso-contour plots and
this greatly facilitated analysis of data.7 The ease of
interpretation has also led to application of the highresolution
technique for anorectal manometry.8

The main limitation with solid-state catheters is the
number of sensors. Currently about 36 sensors spaced
1 cm seems to be the limit. Solid-state technology may
advance but the fiber-optic technique used by Dinning
et al.1 has substantially increased the length of the gut
segment that can be studied with high-resolution
manometry. For the first time, it may become possible
to study in detail also the small bowel. Pioneering
studies in this part of the gut used water-perfused
catheters and were limited to short segments of the
duodenum but were able to demonstrate retroperistalsis
during late phase-III of the migrating motor complex.
9,10 The clinical use of small bowel manometry
has been hampered by a total absence of standardization,
few measurement points, usually two to eight,
and comparatively long distances between sensors
(3–15 cm).11–13 It would be of great interest to find
out what we have missed while doing manometry of
the small bowel in a way that only permits reliable
estimates of migrating motor complexes.13
The digestive functions of the colon mainly consist
of bacterial fermentation of food residues. It is
reasonable to assume that the motor activity of the
colon should be designed for optimizing fermentation,
absorption of water, electrolytes and some nutrients,
and packaging of waste. In the small intestine,
digestion of food and absorption of nutrients are the
main functions. We still know very little about the
relation between meal composition and digestive
motor activity in the small intestine. Early experiments
in dogs indicated that different nutrients were
also handled differently.14 Fat, for example, seemed to
be associated with so-called clustered contractions, a
pattern that has been reported to occur more frequently
in a number of disorders in humans15,16 but
which can also be seen in healthy individuals.17
Hypothetically, clustered contractions could represent
a specialized program aimed at facilitating micelle
formation and digestion of fats. Whether such programs
exist or not can now perhaps be studied using
fiber-optic high-resolution manometry of the small

The report by Dinning et al.1 is a reminder to us all to
avoid thinking that whatwecan measure is all there is to
measure and things thatwecannot measure do not exist.
We may think that intraluminal manometry only
measures the contractile activity of the circular muscle
layer of the gut and that it tells us nothing about the
longitudinal muscle layer. It is true that the muscular
activity of the longitudinal muscle layer cannot easily be
seen on intraluminal manometry. However, mathematical
modeling of esophageal peristalsis with data from
manometry, radio-opaque marker studies and endosonography
indicates that contraction of longitudinal
muscle leads to local longitudinal shortening, which is
coordinated with contraction of circular muscle during
peristalsis.18 This means that the activity of the longitudinal
muscle layer is an integrated part of the
peristaltic contraction and that intraluminal manometry
reflects the activity of both muscle layers.