[Measurement of the colloid osmotic pressure from plasma density by means of the mechanical oscillator technique (author's transl)].

The colloid osmotic pressure of plasma is a clinically and physiologically important variable. Like the plasma density, it is a function of the total concentration of plasma proteins. Thus, plasma colloid osmotic pressure can be determined from measurement of the plasma density. Minor variations are caused by variations of the albumin-globulin ratio and, much less frequently, by increased concentration of low molecular substances in the plasma. The direct measurement of the colloid osmotic pressure is a time consuming and complex procedure. The determination of the plasma density using the mechanical oscillator technique is a simple and fast procedure. From our results we were able to derive and prove the applicability of an equation which permits the calculation of the colloid osmotic pressure from the measured values of the plasma density. The plasma volume needed for the measurement is 0.2 ml, the measuring time amounts to a few seconds.