[Capillary damage following freezing of the extremities, evaluated by fluorescence videomicroscopy]

Four patients with subacute cold injury of the fingers have been examined by dynamic fluorescence videomicroscopy after intravenous bolus injection of Na-fluorescein. Avascular skin areas with no perfused capillaries were detected, a finding best explained by destruction of the microvessels induced by cold injury. Microvascular spasms play an additional role. Transcapillary diffusion of the fluorescent tracer seems to be enhanced in some preserved capillary groups. Cold injury induces microangiopathy characterized by spasms of precapillary vessels, destruction of capillaries in large skin areas, and increased permeability of microvessels still perfused.