Evaluation of Cutaneous Blood Flow Responses by 133Xenon Washout and a Laser-Doppler Flowmeter

Abstract

A new method for noninvasive measurement of cutaneous blood flow is laser-Doppler flowmetry. The technique is based on the fact that laser light is back-scattered from the moving red blood cells, with Doppler-shifted frequencies; these impulses lead to photodetectors and are converted to flow signals. In this work we used a new system with a low noise level. Comparison was made between this technique and the atraumatic epicutaneous 133Xenon technique for measurement of cutaneous blood flow during reactive hyperemia and orthostatic pressure changes. The laser-Doppler flowmeter seems to measure blood flow in capillaries as well as in arteriovenous anastomoses, while the 133Xe method probably measures only capillary flow. A calibration of the laser-Doppler method against the 133Xe method would appear to be impossible in skin areas where arteriovenous anastomoses are present. The changes in blood flow during reactive hyperemia, orthostatic pressure changes, and venous stasis were found to be parallel as measured by the two methods in skin areas without shunt vessels. The laser-Doppler flowmeter would appear to be a useful supplement to the 133Xe washout method in cutaneous vascular physiology, but it is important to keep in mind that different parameters may be measured.

Skin Blood Flow in Diabetic Dermopathy

“…A calibration factor of 6 mL·100 g -1 ·min -1 ·100 Hz has been derived on the basis of theoretical calculations to convert the laser Doppler flow parameter to conventional blood flow units 13 and has been verified in numerous tissues using several reference techniques. [14][15][16][17][18][19] A Vasamedic module TCM 420 was used for controlling local skin temperature. Doppler fiber laser optic probes were inserted into a 19-mm-diameter thermal head attached to a separate solid-state controller.…”

Quantitative Analysis of Skin Flap Blood Flow in the Rat Using Laser Doppler Velocimetry

“…Intradermal 133xenon clearance has also yielded good results (Palmer et al 1972, Young 1982, Young & Hopewell 1983, but this is an invasive method, the results of the injection alone increasing flow dramatically (Holloway 1980). Four noninvasive methods of measurement have been described: (1) atraumatic epicutaneous xenon clearance, a development of the intradermal technique (Englehart & Kristensen 1983); (2) photoplethysmography (Harrison et al 1981, McCaffrey et al 1980; (3) dermatofluorimetry, possibly the most reliable method ofassessment of immediate skin flap viability (Graham et al 1983, Silverman et al 1980, Wiseman et al 1982; (4) laser Doppler velocimetry (Bonner et al 1981, Holloway & Watkins 1977, Stern et al 1977, Watkins & Holloway 1982), a recently developed technique which has now become commercially available.…”

“…Whereas this could also be demonstrated by the laser Doppler in the first 24 hours, it did not seem to be relevant after this (Marks et al 1948a). The laser Doppler measures flow in at least some of these shunts (Englehart & Kristensen, 1983) and by 24 hours there is none beyond the ultimately surviving tip.…”

EEMCO Guidance for the Measurement of Skin Microcirculation

“…Although a good correlation was found between all methods, it is difficult to obtain from these comparisons a unique 'calibration factor', because of high inter-/intrasubject and interstudy variability of the relationship, because of the site specificity of the LDF signal and because of the different significance of reference methods. The appropriateness [26] of a comparison between LDF and the 133 Xe clearance method in the skin has been questioned since LDF seems to measure blood flow in capillaries as well as in arteriovenous anastomoses, while the 133 Xe method probably measures only capillary flow. A calibration of LDF against the 133 Xe method would appear to be impossible in skin areas where arteriovenous anastomoses are present, whereas the changes in skin blood flow are correlated in skin areas without shunt vessels.…”