Ambulatory measurement of nocturnal fluctuations in subcutaneous blood flow rate in the lower leg of man during 12-h periods with the portable CdTe(Cl) detector. Methodological considerations.

Possible sources of error during long-term measurements of subcutaneous blood flow rate with the portable CdTe(Cl) detector system were ruled out in the present study. Local blood flow rates were recorded in the lower legs of normal human subjects by means of the 133Xe wash-out technique. A good correlation was found between the portable CdTe(Cl) and stationary NaI(Tl) detector systems both prior to (r = 0.88, P less than 0.0001) and after (r = 0.68, P = 0.07) day over night (12 h) measurements. Identical post-ischaemic reactive hyperaemia could be demonstrated by both detector systems 12 h after the application of the isotope depot. This indicates that blood flow rates and vascular reactivity can be measured over 12 h by the portable CdTe(Cl) detector. Identical results were obtained during the 12-h measurements performed with the portable CdTe(Cl) detector attached directly to the skin surface and with the detector elevated above the skin surface. Therefore, geometrical changes were without any influence on our measurements. We conclude that measurements of subcutaneous blood flow rates in the lower leg of human subjects can be performed under out-patients conditions by means of the 133Xe wash-out technique and portable CdTe(Cl) detectors. A skin area greater than or equal to 4 cm should be labelled by means of the atraumatic, epicutaneous labelling technique and the detector attached directly to the skin surface with a single layer of a 20-micron thick gas-tight Mylar membrane interposed between the skin surface and the detector. The investigation of the subcutaneous blood flow rate should not be initiated until at least 90 min after labelling.(ABSTRACT TRUNCATED AT 250 WORDS)