RHYTHMICAL VARIATIONS OF HEMOGLOBIN OXYGENATION IN CUTANEOUS CAPILLARIES

The consequences of rhythmical arteriolar vasomotion for nutrition and the tissue oxygen supply to human skin are largely unknown, In the st udy presented here, the periodic variations of haemoglobin oxygenation in the small cutaneous vessels have been evaluated with a new reflect ion spectrophotometer. For the assessment of spatial variations, we ex amined 24 different sites in 20 healthy volunteers. For quantification of the relatively long duration of periodic variations, a Digital Fou rier Transformation with a specially programmed filter was used. In 26 5 out of 480 spectra (55.2%), periodic variations of the haemoglobin o xygenation were found. The average of the main frequency of waves was 7.0 +/- 2.5 cycles per minute. The occurrence of variations of haemogl obin oxygenation depended on the measuring site. In the gluteal region , variations were observed in 17 out of 20 subjects, on the palms in 1 6 out of 20, at the foot plantar in 18 out of 20 in comparison to the cheek (8/20), the lip (5/20) and the eyelid (6/20). On the head we obs erved significantly more variations per minute than in the lower extre mities. Because these variations, with duration of up to 30 s, have a relatively slow dynamic compared with heart rate and breathing frequen cy, consequences for the cutaneous diffusion and metabolism of other s ubstrates are very likely.