EFFECT OF THERAPEUTIC PARACENTESIS ON PLASMA-VOLUME AND TRANSVASCULARESCAPE RATE OF ALBUMIN IN PATIENTS WITH CIRRHOSIS

Background/Aims: Circulatory abnormalities with activation of vasocons trictor systems after large-volume paracentesis are generally consider ed secondary to an increased extravasation of fluid from the intravasc ular compartment to the extravascular space with subsequent reduction in plasma volume, To test this hypothesis, plasma volume, the transvas cular escape rate of albumin, the absolute escape rate of albumin and the activity of vasoconstrictor systems were measured in 25 cirrhotic patients with ascites in baseline conditions and 2 days after total pa racentesis with plasma volume expansion. Methods: Plasma volume and th e transvascular escape rate of albumin, the fraction of albumin passin g from the intravascular to the extravascular space per unit of time, were assessed through the plasma disappearance curve of radioiodinated human albumin, The absolute escape rate of albumin, the total flux of albumin from intravascular to extravascular space per unit of time, w as also calculated. Results: Eight of the 25 patients (32%) developed marked activation of vasoconstrictor systems after paracentesis, In th ese patients, plasma renin activity and plasma norepinephrine concentr ation increased from 6.6+/-2 to 23.4+/-11 ng.ml(-1).h(-1) and 776+/-22 9 to 989+/-258 pg/ml, respectively (p<0.05), No significant changes in these parameters were found in the remaining 17 patients, The activat ion of vasoconstrictor systems occurred in the absence of changes in p lasma volume (3456+/-276 vs 3476+/-264 ml, NS), transvascular escape r ate of albumin (10.4+/-1 vs 10.9+/-2%/h, NS) and absolute escape rate of albumin (9.9+/-1.9 vs 10.5+/-0.7 g/h, NS). Conclusions: These resul ts do not support a contraction of plasma volume as the mechanism resp onsible for activation of vasoconstrictor systems after paracentesis, Rather, the activation of vasoconstrictor systems in the absence of ch anges in plasma volume suggests that paracentesis accentuates the impa irment of ''effective'' blood volume present in cirrhotic patients wit h ascites.