ABSTRACT
The aim of this study is to evaluate and quantify the respiratory dependency of cutaneous laser-Doppler flux motion in two variable innervated sites of the upper extremity (the proximal volar forearm and the fingertip) by using a computer-supported system. Various spontaneous (6-17/ min) and externally triggered (12 or 6/min) respiratory frequencies were used for comparative frequency analysis of the laser-Doppler flux signal. Further, an index (MIRSF) was determined as an indicator of the correlation between flux motion and respiration. The MIRSF is defined as the ratio of the power spectrum of the LDF signal at the specific respiratory frequency divided by the time-averaged LDF for that time period. The MIRSF enables a comparison of different intra- and interindividual flux values. A very high correlation was seen between the respiratory frequency and the MIRSF during spontaneous respiration in the skin of the proximal volar forearm; the lower the spontaneous respiratory frequency, the higher the MIRSF. However, this correlation could not be found in the results of the fingertip. The presence of a constant and therefore externally triggered respiratory frequency increased the modulations of the LDF at both measurement locations. While triggered respiration produced a decline in the taLDF of the fingertip, the taLDF of the forearm was unaffected. Considering the different innervation and hydrostatic effects the results lead to the following conclusion: the finger vessels are richly innervated with adrenoceptors which causes alpha 1-mediated vasoconstriction. In contrast to the vessels of the fingers those of the forearm seem to be under andrenergic as well as cholinergic control. Hydrostatic components appear to be more prevalent in the volar forearm site.
Subject(s)
Autonomic Nervous System/physiology , Heart Rate/physiology , Respiratory Mechanics , Skin/blood supply , Adult , Blood Flow Velocity , Computers , Evaluation Studies as Topic , Female , Humans , Laser-Doppler Flowmetry , Male , Reference Values , Skin/innervation , Sympathetic Nervous System/physiologyABSTRACT
In the study presented, color-coded duplex sonography (CCDS) and laser Doppler flux (LDF) signals from finger tips of 7 healthy individuals were recorded simultaneously. The aim of the study was to examine whether or not the results of a functional test ('deep inspiration') could also be observed with an ultrasonic Doppler. In the literature this test is known to provoke notable blood flow characteristics of the LDF ('inspiratory gasp'), a phenomenon which is caused by a sympathetically mediated vasoconstriction of acral vessels. With regard to the penetration depth of the LDF in skin it was of further interest to determine the distance between the surface of the skin and the vessels found near the surface. We found for CCDS parameters (color pixels/image; time-averaged flow velocity [TAV]; resistance index [RI]) as well as for LDF (flux [taLDF]) significant changes before versus after 'deep inspiration'. CCDS is a new diagnostic tool to visualize also very small vessels down to 0.2 mm, e.g. in finger tips. It should be evaluated which role this method may play in combination with functional tests in diagnostic handling, e.g. of patients with polyneuropathies or collagenoses.
Subject(s)
Fingers/blood supply , Laser-Doppler Flowmetry , Skin/blood supply , Ultrasonography, Doppler, Color , Vasoconstriction/physiology , Adolescent , Adult , Blood Flow Velocity/physiology , Female , Humans , Image Processing, Computer-Assisted , Inhalation/physiology , Male , Microcirculation/physiology , Middle Aged , Reference Values , Regional Blood Flow/physiology , Skin Neoplasms/blood supply , Sympathetic Nervous System/physiology , Vascular Resistance/physiologyABSTRACT
The aim of this study was to show and to quantify the breath-dependency of cutaneous fluxmotion in the volar proximal forearm using a new computer-aided system. A meanflux-related index (MI) representing the intensity of the influence of respiration on fluxmotion was calculated. There was a good correlation between MI and the rate of respiration under spontaneous breathing: the lower the rate of respiration, the higher the value of MI. Prescribing a constant breathing rhythm amplifies this frequency-dependent effect. According to occurrence of low rates of respiration (< 12/min) also under physiological conditions the respiration should be simultaneously recorded while assessing fluxmotion.
