Sunday, February 26, 2012

Autonomic Dysfunction as biomarker

Physiol Meas. 2012 Jan 25;33(2):231-241. [Epub ahead of print]
Chronic fatigue syndrome and impaired peripheral pulse characteristics
on orthostasis-a new potential diagnostic biomarker.
Allen J, Murray A, Di Maria C, Newton JL.
SourceMicrovascular Diagnostics, Regional Medical Physics Department,
Freeman Hospital, Newcastle upon Tyne NE7 7DN, UK.


Autonomic nervous system dysfunction is frequently reported in chronic
fatigue syndrome (CFS) with orthostatic intolerance, a common symptom
that can be objectively assessed. The frequent finding of autonomic
dysfunction and symptoms on standing has the potential to provide a
diagnostic biomarker in chronic fatigue. In this study we explored the
clinical value of non-invasive optical multi-site photoplethysmography
(PPG) technology to assess cardiovascular responses to standing.
Multi-site PPG pulses were collected from tissue pads of the ears,
fingers and toes of 14 patients with CFS and 14 age-matched sedentary
subjects using a measurement protocol of a 10 min baseline (subject
supine) followed by 3 min of tilting on a tilt table (head-up to 70°).
Percentage change in pulse timing (pulse transit time, PTTf) and pulse
amplitude (AMP) at each site were calculated using beat-to-beat pulse
wave analysis. A significant reduction in the overall pulse timing
response to controlled standing was found for the CFS group (using
summed absolute percentage change in PTTf for ear, finger and toe
sites, median change of 26% for CFS and 37% for control with p =
0.002). There were no significant differences between subject groups
for the AMP measure at any site. Changes in AMP with tilt were,
however, weakly significantly and negatively correlated with fatigue
severity (p < 0.05). Receiver operating characteristic (ROC) analysis
of timing measures produced an area under the curve of 0.81.
Experimental linear discriminant classification analysis comparing
both timing and amplitude measures produced an overall diagnostic
accuracy of 82%. Pulse wave abnormalities have been observed in CFS
and represent a potential objective measure to help differentiate
between CFS patients and healthy controls.

PMID:22273713[PubMed - as supplied by publisher]

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