SIMULTANEOUS MEASUREMENTS OF FINGER-TIP TEMPERATURES AND BLOOD PERFUSION RATES IN A COLD ENVIRONMENT

Simultaneous measurements of middle finger-tip temperatures and blood perfusion rates were made in hands exposed to 0 degrees C air. Tempera tures were measured by a thermocouple disk attached to the nail-bed of the finger. Blood perfusion was monitored by a laser-Doppler velocime ter probe attached to the palmar side of the finger-tip. Seven, 60-80 min long experiments were performed on 6 men. The subjects sat in a co mfortable (20-22 degrees C) environment while the test hand was insert ed, at about heart level, into a small non-contacting environmental ch amber. Results indicated a sharp drop in finger-lip temperature of 10. 1 +/- 2.0 degrees C during the initial 2 min. The time-lag between the preceding changes in blood perfusion and the ensuing changes in tempe ratures was in the range of 2-7 (5.86 +/- 1.73) min. Cold induced vaso dilatation was typically effected by triangular-like waves indicating 3 to 20-fold gradual opening-closing changes of the arterial supply of the finger-tip. Average finger-tip temperatures (11.8-15.5 degrees C) showed much less variability among the subjects than did average bloo d perfusion rates (2.8-17.0 mL(b) . mL(t)(-1). hr(-1)). Results of thi s study were compared to an analytical model quantifying finger-tip te mperature and good conformity was obtained. (C) 1997 Elsevier Science Ltd.