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A standardized bedside test for assessment of peripheral sympathetic nervous function using laser Doppler flowmetry
M Schürmann1, G Gradl, H Fürst
1Department of Surgery, Ludwig-Maximilians-University of Munich, Germany.
Microvascular Research
|September 1, 1996
Summary
A new bedside test reliably assesses peripheral sympathetic nervous system function. This noninvasive method uses arousal stimuli to measure fingertip blood flow changes, differentiating healthy individuals from those with sympathetic reflex dystrophy.
Area of Science:
- Neuroscience
- Physiology
- Medical Diagnostics
Background:
- The sympathetic nervous system plays a key role in autonomic disturbances, yet no routine functional test for peripheral sympathetic function exists.
- Reflex sympathetic dystrophy (SRD) is one such condition where understanding sympathetic function is crucial.
Purpose of the Study:
- To develop and validate a standardized, noninvasive bedside test for assessing peripheral sympathetic nervous system function.
- To evaluate the test's reliability and ability to differentiate between healthy subjects and patients with SRD.
Main Methods:
- Laser Doppler flowmetry (LDF) was used to measure fingertip blood flow (FTBF) changes in response to arousal stimuli (inspiratory gasp and contralateral cooling).
- A standardized procedure involving external body heating ensured comparable interindividual results.
- Mathematical analysis of LDF curves yielded parameters like sympathetic response fraction (SRF) and quantification index (QI).
Main Results:
- Healthy subjects exhibited reproducible decreases in FTBF during arousal, indicative of sympathetic vasoconstriction.
- SRF and QI values showed low coefficients of variation, demonstrating test reproducibility and reliability.
- Patients with SRD showed absent or diminished FTBF decreases, with statistically significant differences in SRF and QI compared to healthy controls (P < 0.001).
Conclusions:
- The developed bedside test is a reliable, noninvasive method for assessing peripheral sympathetic nervous function.
- The test effectively differentiates pathological sympathetic responses, making it practical for clinical use, even in patients with upper limb injuries.