'Chronic fatigue syndrome and impaired peripheral pulse
characteristics on orthostasis=96a new potential diagnostic biomarker',
available at- http://iopscience.iop.org/0967-3334/33/2/231
fulltext- http://iopscience.iop.org/0967-3334/33/2/231/pdf/0967-3334_33_2_2=
31.pdf
-------------------------------------------------------------------
http://medicalphysicsweb.org/cws/article/research/48594
Research
Feb 10, 2012
Diagnosing chronic fatigue syndrome
Chronic fatigue syndrome (CFS) is a debilitating condition that
currently occurs in up to 0.4% of Europe's population. Despite the
sizeable volume of research into CFS, no bedside diagnostic tool
currently exists, leaving patients frustrated and seeking answers.
Now, however, a pilot study carried out in the UK and published in
Physiological Measurement, has shown that a simple optical technique
has the potential to identify individuals with CFS (Physiol. Meas. 33
231).
"Our research study explored how we might use the properties of the
peripheral pulse as a diagnostic tool for CFS," said Julia Newton, an
honorary consultant physician at the Newcastle upon Tyne Hospitals NHS
Foundation Trust and within Newcastle University's Institute for
Ageing and Health. "Pulse wave abnormalities were observed in CFS and
represent a potential objective measure to help differentiate between
CFS patients and healthy controls."
A difficult diagnosis
CFS can affect all ages and its cause is unclear. One of the current
difficulties in recognising CFS is the lack of a suitable diagnostic
biomarker. Aware that abnormalities of the autonomic nervous system
are observed in over three quarters of those with CFS and that
orthostatic intolerance is a common symptom, Newton and her
collaborators initiated a pilot study to investigate whether
peripheral pulse characteristics on orthostasis could provide the
biomarker that clinicians and patients alike are searching for.
"The normal homeostatic response to standing is to preserve the brain
at all costs," explained Newton. "The body therefore aims to do what
it can to get the blood back to the brain against gravity by
increasing the heart rate and constricting the peripheral blood
vessels. Our study focused on measuring and assessing pulses from
multiple peripheral sites simultaneously in both CFS patients and
controls in response to a posture change."
Multiple peripheral pulse measurements
The technique employed by the team is known as PPG, or
photoplethysmography. PPG is a simple and safe optical way of
measuring the pulse at easy-to-access peripheral sites such as the ear
lobe, finger tips or toe pads.
The researchers recruited 28 subjects: 14 patients with confirmed CFS
and 14 healthy control volunteers. For each person in turn, the team
simultaneously acquired data from the right and left ear lobes, the
index fingers and big toes using its award-winning multi-site PPG
technology. Baseline measurements were made with the patient lying
supine on a tilt table and collected over 10 minutes. The patient was
then tilted upright to an angle of 70 degrees to the horizontal and
the changes in pulse assessed over a three minute period whilst they
remained in this near-upright position. An electrocardiogram was also
collected during the measurements.
"With each heartbeat, the blood volume changes in the vascular bed of
the tissue and the amount of light shone onto the skin by the probes
varies in synchrony with this, giving a clear pulse with each heart
beat," explained John Allen, a clinical scientist from the Regional
Medical Physics Department of Newcastle's Freeman Hospital. "The pulse
waveform has many features in terms of its size, shape and the time
for it to get from the heart to the periphery as well as beat-by-beat
variability. We used special computer analysis techniques to extract
various pulse features and compared these to data from normal subjects
to provide the diagnostic information."
Following off-line analysis, the team found that there were
significant differences between the CFS group and the controls for
combinations of pulse amplitude and timing measurements, with a strong
diagnostic bias coming from the ear lobe site.
"We think that the ear measurements could be influenced by cerebral
autoregulation (CA), the reflexes that preserve brain blood flow at
all costs," said Newton. "Cognitive problems are common in those with
CFS. Further research applied to a larger number of subjects should
help decide the most reliable combination of pulse features to measure
so that the technique can be applied to a general population for
screening of CFS with full confidence."
About the author
Jacqueline Hewett is a freelance science and technology journalist
based in Bristol, UK.
---------------------------------------------
Send posts to CO-CURE@listserv.nodak.edu
Unsubscribe at http://www.co-cure.org/unsub.htm
Select list topic options at http://www.co-cure.org/topics.htm
---------------------------------------------
Co-Cure's purpose is to provide information from across the spectrum of
opinion concerning medical, research and political aspects of ME/CFS and/or
FMS. We take no position on the validity of any specific scientific or
political opinion expressed in Co-Cure posts, and we urge readers to
research the various opinions available before assuming any one
interpretation is definitive. The Co-Cure website <www.co-cure.org> has a
link to our complete archive of posts as well as articles of central
importance to the issues of our community.
---------------------------------------------
