Endoscopic visible light spectroscopy: optimizing the accuracy of diagnosing chronic gastrointestinal ischemia with luminal feeding stimulation (VLS-Study)

Diagnosing chronic gastrointestinal ischemia remains a challenging quest.The
standard diagnostic work-up of CGI suspected patients consists of clinical
symptoms, radiological imaging and mucosal oxygen saturation measurement with
visible light spectroscopy (VLS) in fasting state. With this diagnostic work-up
detection of chronic gastrointestinal ischemia is acceptible, but better
diagnostic methods with higher sensitivity are needed to identify patients.
Several studies already have shown that patients with chronic gastrointestinal
ischemia have an lesser increase in splanchnic blood flow after oral caloric
stimulation compared to healthy subjects and that this leads to mucosal
ischemia of the gastrointestinal tract . Mucosal oxygen saturation using
endoscopic visible light spectroscopy after luminal feeding stimulation may
thus lead to better identification of patients with chronic gastrointestinal
ischemia .

Also, the microcirculation is the main site of oxygen delivery to tissue cells.
Several studies have shown that microcirculatory alterations are related to
hemodynamic changes which have been reported to impair intestinal perfusion
(1-3). In these patients, the sublingual capillary perfusion seems well
correlated to the hypoxic state of the gastric mucosa (4). However, these
studies were performed in critically-ill patients with acute gastrointestinal
ischemia. Up until now, no studies are performed to investigate the
relationship between sublingual microcirculation and chronic hemodynamic
changes such as in patients with CGI.
Therefore, sublingual measurement of the microcirculation can bring us more
insight in the pathophysiology of gastrointestinal ischemia which may lead to
development of new and less burdensome methods for the detection of
gastrointestinal mucosal ischemia.

References:
1. Trzeciak S, McCoy JV, Phillip Dellinger R, et al. Early increases in
microcirculatory perfusion during protocol-directed resuscitation are
associated with reduced multi-organ failure at 24 h in patients with sepsis.
Intensive Care Med. 2008 Dec;34(12):2210-7.
2. De Backer D, Donadello K, Sakr Y, et al. Microcirculatory alterations in
patients with severe sepsis: impact of time of assessment and relationship with
outcome. Crit Care Med. 2013 Mar;41(3):791-9.
3. Boerma EC, Kaiferova K, Konijn AJ, et al. Rectal microcirculatory
alterations after elective on-pump cardiac surgery. Minerva Anestesiol. 2011
Jul;77(7):698-703.
4. Creteur J, De Backer D, Sakr Y, Koch M, Vincent JL. Sublingual capnometry
tracks microcirculatory changes in septic patients. Intensive Care Med. 2006
Apr;32(4):516-23.

- To determine the difference in baseline mucosal oxygen saturation
measurements and after luminal feeding between patients diagnosed with CGI and
healthy subjects.
- To determine the difference in baseline mucosal oxygen saturation
measurements prior to and after treatment inpatients diagnosed with CGI with
persistent relief of symptoms after treatment.
- To asses sublingual microcirculatory alterations before and 60 minutes after
luminal feeding stimulation in patients with and without CGI
- To determine whether there is a correlation between sublingual
microcirculatory alterations and mucosal saturation measurements using VLS

A prospective cohort study to evaluate the diagnostic accuracy of visible light
spectroscopy measurements after luminal feeding stimulation for detection of
chronic gastrointestinal ischemia.
Patients suspected of chronic gastrointestinal ischemia referred to our
hospital for further evaluation are asked whether they want to participate in
our study in which next to the standard work-up, sublingual microcirculatory
measurements using a videomicroscope and additional mucosal saturation
measurements are performed after stimulation with luminal feeding.
The difference of mucosal oxygen saturation measurements and sublingual
microcirculation measurements before and after luminal feeding stimulation will
be compared for the overall group. The difference in mucosal oxygen saturation
measurements for patients diagnosed with chronic gastrointestinal ischemia will
be compared to the healthy volunteers. We then will investigate the value of
the mucosal saturation measurement after luminal feeding in the diagnosis of
chronic gastrointestinal ischemia.

Gastroduodenoscopy with baseline mucosal oxygen saturation measurements are
already well accepted and incorporated in the standard work-up for patients
suspected of CGI. A second gastroduodenoscopy with mucosal oxygen saturation
measurement will therefore only take an additional 20 minutes and if patient is
diagnosed and treated for CGI he will again be asked to for an additional
gastroduodenoscopy with mucosal oxygen saturation measurements.
No additional visits to the hospital are required as the mucosal oxygen
measurements with VLS for the standard work-up. The additional VLS and
sublingual microcirculatory measurements will be performed during the same
clinical setting, in doing so also limiting the total amount of conscious
sedation and no longer duration of hospital stay is required.
Although most patients with CGI already present with postprandial pain in daily
life, abdominal pain may occur when stimulation with luminal feeding begins. We
will be well aware of this pain and ask patient several times if the pain
occurs and stop if necessary.

Participation in this study will bring no additional benefit for the individual
patient.
However this study will provide valuable information on the predictive value
and diagnostic accuracy of VLS measurements in the usual fasting condition and
after feeding stimulation in the diagnosis of CGI. Therefore this test could be
beneficial for the whole patient group since this prospective study may lead to
identification and better recognition of patients with gastrointestinal
ischemia and therefore could lead to more rapid treatment.
Performing mucosal saturation measurements in healthy subjects will make it
possible to readjust and optimalize the current VLS cut-off values applied to
diagnose patients with chronic gastrointestinal ischemia. This will be the
first study to obtain baseline normal mucosal saturation values of different
sites in the gastrointestinal tract actively excluding for confounders and
reducing the risk of bias. Also we will be able to better understand the
physiological differences between healthy subjects and patients with chronic
gastrointestinal ischemia in their reaction to stimulation with food.

This prospective study will provide valuable information on the predictive
value of VLS measurements and its power to select patients for treatment. It
will also provide us more insight in the relationship between the
microcirculation and hemodynamic changes in the gastrointestinal tract. This
may lead to development of more rapid, less-burdensome and more advanced
diagnostic methods for the detection of gastrointestinal ischemia.