PREDICTION OF DRY-WEIGHT THROUGH CHANGES IN BLOOD-VOLUME AND PLASMA CYCLIC 3',5'-GUANOSINE MONOPHOSPHATE IN PATIENTS UNDER MAINTENANCE HEMODIALYSIS

Dry weight evaluation is generally made from clinical observation of b ody weight (BW) changes, edema, blood pressure, and chest radiograph. In fact, 25-50% of patients on chronic hemodialysis had an incorrectly determined dry weight. To predict dry weight, twenty stable patients on regular hemodialysis were enrolled to investigate the correlation a mong dry weight, hematocrit, blood volume (BV), and vasoactive hormone s including plasma renin activity (PRA), aldosterone (PA), and cyclic 3',5'-guanosine monophosphate (cGP) values. BV was estimated by an inf rared light reflection method. PRA, PA, and plasma cGMP were determine d by commercial radioimmunoassay kits. The results showed significantl y decreasing plasma cGMP values toward the end of hemodialysis compare d with before hemodialysis (15.76 +/- 3.56 pmol/ml vs 33.57 +/- 3.98 p mol/ml; p < 0.05). A significant correlation exists between changes in plasma cGMP values and BV (p < 0.05). In addition, no significant cor relation exists between changes in plasma cGMP and BW. A good correlat ion was found between changes in BV and hematocrit throughout dialysis (r = -0.774; p < 0.001). PRA and PA values predict neither BV nor BW changes. All patients were treated to attain a further ultrafiltration of 0.5 to 1.0 L after reaching dry weight, and we found that the crit ical point in blood pressure drop occurred when BV decreased by 8% or when plasma cGMP values decreased by 50% from their initial values. Co ntinuous BV monitoring with infrared light reflection and detecting of cGMP throughout hemodialysis could help predict dry weight and avoid dialysis hypotension.