[Erythrocyte and plasma volume as well as the relationship between body hematocrit and venous hematocrit in various stages of essential and renovascular hypertension]

Renal clearance determination with one blood sample: improved accuracy and universal applicability by a new calculation principle

A sufficiently accurate quantification of renal function requiring only one plasma sample without an additional gamma camera study has until now only been possible in adults. A new principle has been developed that allows the universal application of known algorithms, irrespective of the clearance substance used, by normalizing the plasma concentrations with respect to individual body dimensions of adult as well as infant patients. In this respect, algorithms are established for clearance determinations using technetium-99m mercaptoacetyltriglycine which are based on steady-state studies as the reference. They allow the calculation of quantitative clearance values in infants and require the drawing of only one blood sample at any time between 25 and 40 minutes postinjection. The comparison with a combined-camera/two-plasma-sample technique performed in 46 children ranging in age from 9 days to 14 years (mean, 6.05 years) resulted in a standard deviation of 8.5% from the line of identity (r = 0.94). Moreover, this procedure also increases accuracy in adult patients, especially those with impaired renal function.

[Plasma renin activity, plasma volume extracellular fluid volume and cardiac output in essential hypertension (author's transl)]

The plasma renin activity (PRA), the plasma volume (PV), the extracellular fluid volume (ECV), the cardiac output and the peripheral vascular resistance (TPR) were determined in 51 patients (14 women, 37 men) with essential hypertension of varying severity. The following findings were achieved: 1. In 9 of the 51 patients with essential hypertension (approximately 18%) a low and non-sensitive PRA was detected. 2. PV, ECV, cardiac output and the calculated peripheral vascular resistance of the essential hypertensive patients with low and non-sensitive PRA did not differ significantly from those of the essential hypertensive patients with normal or elevated PRA. 3. The hypertensive patients with low and nonsensitive PRA had the highest average arterial pressure. From these findings it can be concluded that the essential hypertensive patients with low PRA are not an homogeneous group. It is assumed that in a subgroup the elevated blood pressure may be the cause of the renin suppression.

A reassessment of intravascular volume measurements in protein--calorie malnutrition

Accurate determination of plasma volume is difficult in oedematous protein--calorie malnutrition, but present studies on the equilibrium of labelled red cells have shown that red cell volume measurements are valid in this syndrome. The red cell volumes have been measured in afflicted Bantu children during a refeeding programme. Expression of the results in ml/kg, ml/m2 or ml/cm is misleading and has been replaced by expressing the results as a percentage of the means of the normal values for the height. The results show that the red cell volume increase that ought to occur at the end of refeeding programme (and hence the iron requirement) is far higher than suggested by the packed cell volume. With treatment the red cell volume increases slowly. The red cell volume and plasma volume changes that occur during treatment do not take place at the same rate.

[Red cell mass and plasma volume in chronic cor pulmonale (author's transl)]

Red cell mass and plasma volume were simultaneously measured by Cr51 and J125-albumine, respectively, in 36 patients with chronic obstructive lung disease and cor pulmonale. Additionally, pulmonary function tests and arterial blood gas analyses as well as pulmonary circulatory and right ventricular hemodynamic measurements were performed the same day. Patients were divided into 3 clinical subgroups: 1. a predominantely emphysematous A-type (n =12), 2. a predominantly bronchial B-type (n = 12), and 3. an intermediate type (n = 12) with about equal scores for A and B. With regard to the cardiac state, A-patients were clinically characterized by small ptotic hearts on chest x-ray and the absence of overt cardiac failure during the whole course of illness whereas B-patients generally showed radiological evidence of heart dilatation associated with recurrent episodes of manifest right ventricular failure. Patients of the intermediate type mostly had recovered from cardiac failure. The following results were obtained: 1. Red cell volume, plasma volume, and total blood volume were within normal limits in A-patients and in patients of the intermediate type. A marked hypervolemia in B-patients was almost entirely due to an increased red cell volume. 2. Close correlations of the red cell volume and total blood volume, respectively, to the arterial PO2 as well as to the arterial PCO2 could be established. 3. Total blood volume was significantly correlated to certain hemodynamic parameters, including cardiac output, stroke volume, pulmonary artery pressure, and right ventricular enddiastolic pressure. 4. The quotient body hematocrit/venous hematocrit was lowered to a significant degree as compared to normal subjects. As a consequence, indirect determination of red cell volume and total blood volume from plasma volume and venous hematocrit leads to a consistent overestimation of both parameters, amounting to 28% in the mean for the red cell mass and to 12% for the total blood volume in the present series.