Influence of Local and Environmental Temperatures on Cutaneous Circulation with Use of Laser Doppler Flowmetry

The purpose of this study was to determine a standard set of conditions for detecting peripheral arteriosclerosis with ischemia. One series of studies was done to determine the influence of room tempera ture on peripheral flow in healthy subjects and patients with peripheral vascu lar disease. The room temperature was varied from 30° to 35°C. The temperature from 24° to 30°C had only minor effects on the circulation. Thus, it seemed appropriate to use a room temperature in the lower range, usually 23°C. Another series of studies showed the effect of changing skin temperatures locally at the finger tip or toe tip on the plantar and volar surfaces in healthy subjects and in patients with peripheral vascular disease. Results showed that as temperature was increased from 10° to 45°, there was a marked increase in the finger and toe circulations, which was considerably greater in the normal sub jects as compared with those with digital disease. The ideal temperature at which to work as a routine is 40 ° C as opposed to the lower temperatures, which did not separate healthy subjects from patients with peripheral vascular dis ease. A third experiment was done to study normal subjects and patients by using the finger circulation as control against the toe circulation when the conditions were a local skin temperature of 40 ° C and a room temperature of 23°C. A toe- finger index was established to detect abnormalities in the circulation. An index using a part of the body as its reference has been used in many other physical measurements such as the ankle/wrist pulsation ratio or Doppler pulse ratio. Use of the index excludes the cardiac output from the ratio measurements. The index narrows the range of normal subjects as compared with single measure ments made on various individuals.