Abstract
Background: The cutaneous vasomotor response may be a biological marker of anxiety. Vasoconstriction of skin blood vessels in anxious subjects has been previously demonstrated by plethysmography. Building on recent studies which have used laser Doppler flowmetry to measure changes in skin and regional blood flow in animals, this study investigates laser Doppler flowmetry measures of skin blood flow in response to a series of alerting stimuli presented to normal human subjects.
Method: Cutaneous vasomotor responses to both auditory stimuli and a series of cold tests were measured by laser Doppler flowmetry in ten healthy subjects. Latency and magnitude of responses were measured and compared to pulse rate changes. Trough latencies as well as recovery times were also measured. Evidence of habituation or sensitisation of responses to stimuli was investigated.
Results: A reduction in skin blood flow followed each stimulus. The skin blood flow response to stimuli was clearly discernible from background activity. Habituation of the response to auditory stimuli was demonstrated in male subjects and found to be statistically significant. In contrast, pulse rate changes following stimulus presentation were small, failed to show any consistent trend and did not habituate.
Conclusion: Skin blood flow responses were clearly demonstrable and measurable by LDF and showed much less equivocal responses to stimuli than pulse rate changes. Latency of responses were consistent with those previously reported in tests of autonomic function. Habituation was evident. LDF measures of skin blood flow have potential as a biological marker of arousal and warrant further investigation.