Quantification of weal reactions with laser Doppler flowmetry. Comparative blood flow measurements of the oedematous centre and the perilesional flare of skin-prick histamine weals.

Skin-prick experiments with different concentrations of histamine (0.1 mg/ml, 1.0 mg/ml, 10.0 mg/ml) and isotonic NaCl solution for control were performed on the forearms of 10 healthy volunteers. Regular recordings of the cutaneous blood flow by laser Doppler flowmetry were performed in the centre of the weals and 5, 10, 15 and 20 mm from the centre representing the zone of perilesional flare. In the weal centre the blood flow was increased but neither different concentrations of histamine nor the control reaction could be differentiated. Recordings performed 5 and 10 mm from the centre showed, however, significant differences between the different solutions of histamine tested as well as the control reaction. The better differentiation was obtained 5 and 10 min after skin-prick. In conclusion, laser Doppler flowmetry with recordings of the perilesional flare is found useful for quantification of weal reactions.