Sodium nitroprusside iontophoresis on the finger pad does not consistently increase skin blood flow in healthy controls and patients with systemic sclerosis

The iontophoresis of SNP leads to a consistent, non axon reflex-dependent, increase in cutaneous vascular conductance in the forearm, both in patients with SSc and in healthy controls. On the finger pad however, such hyperemia was not consistent. As a consequence, other tools should be considered to assess non endothelium-dependent skin microvascular function in the finger pad.