Clinical Application of Laser Doppler Flowmetry for Measurement of Cutaneous Circulation in Health and Disease

Abstract

The cutaneous laser Doppler device (LDF) was employed to determine its usefulness in differentiating the circulation of the feet in normal subjects from that in patients with arteriosclerosis obliterans. It is shown that the laser Doppler frequencies correlated well with results from venous occlusion plethysmography, which measured volume rate of flow. Thus, one can determine volume rate of flow by the simple Doppler method. There was a linear relationship between these two methods of measurements. Using the LDF method, it was determined that normal individuals have toe flows that on the average are 42% of finger flows in supine resting subjects. In peripheral vascular disease of the lower extremities, the LDF measurements showed a decreased circulation in the large toes when the patients are supine and the lower extremities flat. The results between health and disease are exaggerated by elevating the feet, at which time the diseased circulation falls to extremely low values compared with those of normal subjects. A similar decrease in skin oxygen tension in the diseased lower extremities was observed when the limbs were elevated.

Decreased skin blood flow early in the course of streptozotocin-induced diabetes mellitus in the rat

“…100 gm 1. min-~ 100 Hz [11]. In all tissues sampled, using different comparison techniques, values have fallen within 15 % of this derived calibration factor [14,16,22,23].…”

“…Blood flow is the product of linearized volume and velocity. This flow parameter, in units of Hz, has been correlated with values obtained using video microscopy [13], thermal [14,15] and H2 clearance [16][17][18], xenon washout [19,20] as well as microsphere deposition [17,21,22] and plethysmography [15,23] in a wide variety of human and animal tissues. There are good correlations among these various methods, given that each method measures microcirculation at different levels of surface penetration.…”

Combining laser-doppler flowmetry and photoplethysmography to explore in vivo vascular physiology

“…In contrast, LDF quantitatively describes (although by arbitrary units), the velocity of moving erythrocytes in microvascular beds by the frequency change suffered by a laser beam that impinges upon them. Multiplying this velocity by a stochastic estimation of the number of cells, a value of 'flow' is estimated [14] . Due to its higher sensitivity, in comparison to PPG, LDF is more suitable for the assessment of the small oscillations found in the microvascular flow and, consequently, for the study of its local regulatory mechanisms [15] .…”

“…Em contraste, a FLD descreve quantitativamente (apesar de por meio de unidades arbitrárias), a velocidade de movimentação dos eritrócitos nos vasos microcirculatórios, pela alteração de frequência sofrida por um feixe de radiação laser que sobre aqueles incide. Multiplicando esta velocidade por uma estimativa estocástica do número de células, é estimado um "fluxo" [14] . Devido à sua maior sensibilidade comparativamente ao FPG, o FLD é mais adequado para a avaliação de oscilações mais pequenas encontradas no fluxo microvascular e consequentemente, para o estudo dos seus mecanismos regulatórios locais [15] .…”

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.…”