Neurovascular responses to sequential deep inspirations assessed via laser-Doppler perfusion changes in dorsal finger skin

A vasomotor reflex triggered by a rapid and deep inspiration causes arteriolar vasoconstriction and a transient decrease in skin blood flow in most people. This is the inspiratory gasp vascular response (IGVR). The most common site of its measurement has been on the palmar or plantar aspect of the digits and little is known about its features in skin with few or any arterial venous anastomoses (AVAs). A basic aspect of this response that has not been systematically studied is its temporal pattern associated with multiple sequential inspiratory gasps (IG) in the same person. Such information would provide insight as to whether there is any form of adaptation or temporal dependence and may serve as a basis for judging response variability. Thus, the present study was undertaken to characterize the normal pattern of responses in finger dorsum skin in a group of 28 normal persons who performed 21 sequential, uniformly spaced IG, over an interval of 42 min. The results show that IGVR measured on the finger dorsum have a magnitude comparable with that obtained on finger pulp, in spite of the relative dearth of sympathetically controlled AVAs on the dorsum. It was also found that the magnitude of the IGVR displays little if any tendency for sequential adaptation or temporal trending. Finally, the results indicate that the largest component of response variability is associated with subject-to-subject differences as compared with sequential variability within subjects