[The technical construction of a computer-supported measuring unit for in-vivo capillary pressure measurement in human nail fold capillaries].

Capillary pressure (CP) is an important determinant of microvascular function. According to Frank Starling, it governs not only the viscosity of the blood and the permeability of the capillary membrane, but also filtration and reabsorption in the microvascular bed. Despite its great significance, the technique of CP measurement is employed in only a few laboratories throughout the world owing to the technical difficulties involved in carrying out such measurements. The first attempts were made by Carrier and Rehberg in 1923. In 1979 Mahler carried out the first dynamic recordings of capillary pressure. The present paper explains the physical basis for direct capillary measurement, and recent progress in this technique is discussed in a review of the literature. We also introduce a newly developed computer-aided system that enables in vivo determination and evaluation of pressure in the nailfold capillaries of the hands and feet. The device permits the simultaneous recording of pressure and bloodflow in the capillaries of the skin, and thus provides additional information on important functions of the cutaneous microcirculation.