Physiology of the peaked finger pulse in normal and cold-sensitive subjects

A unique peaked digital pulse contour (DPC) is frequently observed in patients with cold sensitivity, but the pathophysiology of this pulse remains obscure. To investigate the responses of the DPC to cold exposure, finger blood pressure (FBP), finger blood flow (FBF), and finger skin temperature (FST) were measured in fingers of both hands of 13 normal subjects and in 16 patients with cold sensitivity. The ratio, FBP/FBF, was used to estimate small vessel resistance (SVR). One hand was immersed sequentially in water at 40 degrees, 30 degrees, 20 degrees, and 10 degrees C, while the other hand remained in room air. DPCs were classified as normal (N), intermediate (I), intermediate-peaked (IP), peaked (P), obstructive (O), and spastic obstructive (SO). At room temperature, fingers with I, IP, O, and SO pulses had increased SVRs and decreased FSTs, and those with O and SO had decreased FBP. On cold exposure IP pulses appeared in both hands of both normal and cold-sensitive subjects, but P pulses developed only on the cooled side. IP and P pulses were associated with an increase in SVR. We concluded that IP pulses are related to reflex sympathetic arteriolar vasoconstriction, that P pulses imply vasoconstriction produced directly by cold exposure, and that O, SO, or absent pulses are indicative of digital arterial vasospasm.