HEMODYNAMICS IN NAILFOLD CAPILLARIES OF PATIENTS WITH SYSTEMIC SCLERODERMA - SYNCHRONOUS MEASUREMENTS OF CAPILLARY BLOOD-PRESSURE AND RED-BLOOD-CELL VELOCITY

There is increasing evidence that endothelial damage occurs at a very early stage during the course of systemic scleroderma. Endothelial dam age is accompanied by impaired microvascular function, which has clear ly failed in patients with systemic scleroderma, as evidenced by necro sis of the fingertips in severe cases. We investigated two important d eterminants of microvascular function, namely capillary blood pressure and capillary red blood cell velocity, simultaneously in the same cap illary. In patients with systemic scleroderma and in healthy volunteer s matched for age and sex, capillary blood pressure was measured by di rect cannulation and capillary red blood cell velocity by video micros copy, Capillary blood pressure and capillary red blood cell velocity w ere significantly lower in patients (14.27 +/- 4.34 mmHg, 230 +/- 310 mu m per a) than in healthy controls (19.06 +/- 3.69 mmHg, p < 0.008, and 910 +/- 240 mu m per s, p < 0.003) at an ambient temperature of 22 degrees C, whereas no significant difference in skin temperature was observed (23.7 +/- 0.9 degrees C vs 24.7 +/- 1.9 degrees C) and no occ lusion of finger arteries was detected. Capillary blood pressure in en larged capillaries did not differ from that in normal-shaped capillari es in the patients (correlation of diameter and capillary blood pressu re, R-2 = 0.04), which was also the case with capillary red blood cell velocity (R-2 = 0.13), Capillary pulse pressure amplitude and capilla ry red blood cell velocity showed a strong correlation (R-2 = 0.81), s uggesting that the pressure gradient across the capillary loop, which is the driving force for capillary red blood cell velocity, was mainly dependent on precapillary resistance. These observations reflect the inadequate microvascular function in systemic scleroderma, which may b e due mainly to a pathophysiologic functional increase in precapillary resistance, even at comfortable ambient temperatures.