Vasodilator iontophoresis a possible new therapy for digital ischaemia in systemic sclerosis?

This study investigated whether whole finger vasodilator iontophoresis increases digital blood flow in patients with systemic sclerosis (SSc): If so, this might indicate a novel approach to therapy.

Eight patients and 8 healthy controls underwent whole finger iontophoresis using a specially designed chamber. Treatment was with 0.5% sodium nitroprusside (NaNP) or 1% acetylcholine chloride (ACh), and the procedure then repeated with the other vasodilator (randomly assigned order). Three treatments were carried out for each chemical; 2 min treatments were carried out bilaterally at 200 microA, a third was then carried out for 5 min on one digit only (randomly assigned to left or right). Blood flow increases were monitored with laser Doppler imaging (LDI). Maximum perfusion increase from baseline (MAX) and the area under the time perfusion curve (AUC), normalized for baseline, were calculated. Data were compared with a three-way analysis of variance test.

Perfusion increased in both patients and controls, but significantly more so in controls (P(MAX) = 0.001, P(AUC) = 0.005, respectively). Values were significantly higher for the 5 min treatment compared with the 2 min treatment (P(MAX) = 0.011 and P(AUC) = 0.008 for both groups). No significant differences were found between the use of NaNP and ACh.

The increased perfusion with both ACh and NaNP in the patient group (albeit to a lesser degree than in the control group) indicates that this local approach to vasodilation is effective. Increasing iontophoresis time causes more sustained vasodilation. Further studies are indicated to investigate a possible therapeutic effect in patients with severe digital ischaemia.