Studies of cutaneous blood flow of normal forearm skin and irritated forearm skin based on high-resolution laser Doppler perfusion imaging (HR-LDPI).

Abstract

High resolution laser Doppler perfusion imaging (HR-LDPI) is a non-touch method used for mapping cutaneous microcirculation. The aim of the present study was to investigate the usefulness of this technique for studies of cutaneous blood flow of normal untreated forearm skin and for the assessment of weak irritant reactions induced by exposure to sodium lauryl sulphate (SLS). 12 healthy volunteers participated in the study. Initially, basal flow was measured for 6 selected test areas on the right forearm. 24h occlusive application of 0%; 0.125%; 0.25%; 0.50% and 1.0% SLS was performed. An untreated skin area was also included. Test sites were clinically evaluated and the cutaneous blood flow was measured using HR-LDPI on days 2, 3 and 5. The results of the present study show that HR-LDPI is a useful technique for assessing the mean cutaneous blood flow of both normal and irritated forearm skin. The rectangular region of interest (R-ROI) method was found to be superior to the threshold region of interest (T-ROI) method in image analysis of the mean blood flow of individual scans. The results showed that even though spatial variation within a skin region may be considerable, no intraregional differences or daily variations in mean basal flow of selected skin areas on the forearm could be found. Due to the low variability, it should not generally be necessary to include an untreated control site as each site should act as its own control. The temporal variation in skin perfusion was minor compared with the spatial variation. This was found both for normal and irritated skin. Therefore, one scan of each area of interest should normally be sufficient. Clinical irritation scores on day 3 were more evenly distributed than those on days 2 and 5. An increase in mean perfusion, as a function of the clinical irritation score, was found. However, no statistical differences could be found in mean perfusion for the selected dose levels of SLS.