Microcirculatory methods for evaluating the effect of vasoactive drugs in clinical practice.

Abstract

Microcirculatory methods have to be used in order to be able to evaluate the effect of vasoactive drugs in ischemic skin areas. During the past two decades several new such techniques for studying the microcirculation in man have been developed. These techniques have shown to be of great value for evaluating drug effects in patients with disturbed peripheral circulation. One such method is the non-invasive Laser Doppler technique. It measures both the nutritional and the non-nutritional thermoregulatory vascular bed of the skin. The data achieved are only semiquantitative, but the method has been shown to be clinically very useful for studying the dynamics of total skin microcirculation in a specific area. In order to be able to study directly what happens in the nutritional capillaries microscopical methods have to be used. Two such techniques are available in clinical practice. By an ordinary light microscope the capillaries can be directly visualized. A specific classification system can be used to evaluate the degree of ischemic damage to an area. The effect of different kinds of therapeutic procedures for improving the microcirculation in an ischemic area can be easily evaluated. By the combination of a light microscope and a sensitive TV-camera the blood flow in single skin capillaries can be measured at a magnification of 250-1 000 times. This method is well suited for testing the immediate effects of vasoactive substances on the nutritional skin circulation both in healthy subjects and in patients with different kinds of cardiovascular diseases.