The Measurement of Myocardial Microflow and Its Reaction to Hypoxia and Hypercapnia

Abstract

Determination of moycaridal microcirculation was performed using chemically generated hydrogen (Lübbers and Stosseck 1970). With this measurement a tissue area is involved which is smaller than the average capillary supply volume. Thus, the usual representation of flow as flow/volume cannot be strictly applied. As Wodick (1973) has shown this method measures the flow which penetrates a perpendicular plane, therefore the flow is expressed as flow/area. The radius of this plane is approximately 150 um. Hydrogen coming from the generating “electrode” must pass through this theoretical plane, and the microflow is calculated as an intergrated value of flow velocity over the surface of this plane. To compare the flow/area with the flow/volume values we have to divide our value by the vessel lengths through which gas exchange can occur. Not being able to exactly determine the length of the vessels, we assume from a mean blood flow of 75 ml/100 g min a length of approximately 2.4 mm.