Aeonose and Complex Regional Pain Syndrome

CRPS
Complex Regional Pain Syndrome (CRPS) is a disabling neuropathic pain syndrome
characterized by spontaneous or stimulus-evoked pain, oedema, vasomotor, and
sudomotor abnormalities, motor dysfunction, and trophic changes, but with no
clear evidence for peripheral nerve injury. Though varying suggestions have
been made, such as inflammation, altered sympathetic activity, ischemia, and
reperfusion injury and central sensitization, the underlying mechanism of CRPS
is as yet unclear. Moreover, the therapeutic interventions for the management
of this disease are both controversial and limited. These therapeutic
strategies include pharmacologic pain relief, sympatholytic interventions, and
rehabilitation.
Furthermore, to date there is no specific laboratory test for CRPS; diagnosis
of the disease is based on clinical observations of signs and symptoms and on
tests such as the WHO analgesic ladder, quantitative sensory testing (QST),
autonomic testing that include quantitative sudomotor axon reflex test (QSART)
for sweating abnormalities, the cold pressor test in conjunction with
thermographic imaging to observe the vasoconstrictor response, and laser
Doppler flowmetry to monitor background vasomotor control. Until a better
understanding of mechanistic overtones helps to put in place mechanism-based
therapeutic strategies, management will continue to be built around a
rehabilitation model.

Aeonose
Pathological conditions often cause metabolic changes in the body resulting in
measurable changes in the blood. At the lung surface, there is an intensive
exchange of organic compounds between the blood and the air in the lungs. We
call them volatile organic compounds (VOC*s). Our human olfactory system is
mostly unable to detect these components, sometimes however it can (e.g.
acetone in diabetic patients).
Using exhaled air as potential diagnostic indicator is increasingly common. The
electronic nose technology is a diagnostic test able to detect a pattern of
volatile organic compounds (VOC*s) in exhaled air.
Basically, it consists of a number of metal-oxide sensors following a cyclic
temperature profile. On the sensor surface, redox-reactions can take place
changing the conductivity of the sensor. This conductivity change is measured
at several positions within the temperature cycle and is dependent upon a.o.
the volatiles present, reaction products, reaction dynamics, and temperature.
The multi-way data generated are being compressed and consequently analysed
using statistical techniques.
Electronic noses are already used for different medical purposes including the
diagnostics of asthma, chronic obstructive pulmonary disease, urinary tract
infection, wound infection, and even cancer. An electronic nose is also used
for the laboratory-based identification of bacterial pathogens.

We expect the Aeonose is able to detect CRPS as well. The cells involved in
inflammation might be detected in the exhaled air.

The goal of the study is to investigate whether the Aeonose can detect a
CRPS-specific pattern of volatile organic compounds in the exhaled air of
patients with CRPS.

This study is a prospective investigator blinded observational study

Subjects will be asked to breath gently through the Aeonose for five minutes,
with a little clamp attached to their nose. This might cause some slight
discomfort. This feeling often passes when they breathe on for some time. When
the discomfort becomes too much, the measurement will be ceased.
Participation in the study is not associated with any further risk.