Measurement and significance of the pulmonary capillary wedge pressure in children with nephrotic syndrome

Abstract

Objective The formation of edema in children with nephrotic syndrome (NS) will involve both of the underfill and overfill mechanisms. It has been recognized that there is a variety of changes in the plasma volume in NS patients. The present study was designed to determine whether the pulmonary capillary wedge pressure (PCWP) could reflect the changes of the plasma volume in NS children. Methods PCWP was measured by using echocardiography techniques, detecting plasma atrial natriuretic factor (ANF, radioimmunoassay method) and hematocrit in 14 NS children, 5 poststreptococcal glomerulonephritis children and 10 normal controls. Results (1) In the edema phase compared with the remission phase, 4 of 14 NS children showed an increased PCWP, which was accompanied by an increased ANF and a decreased HCT; 3 of 14 showed a decreased PCWP, which was accompanied by a decreased ANF and an increased HCT; the rest of 7 NS children showed no change in PCWP along with the other indexes. There were no significant differences in the levels of PCWP, ANF and HCT between the NS children in the remission phase and the normal controls. PCWP was positively correlated with ANF (r=0.76 P<0.001)and negatively correlated with HCT (r=-0.61 , P<0.001). There was a negative correlation between ANF and HCT(r=-0.59 , P<0.001). (2) Fifteen minutes after the infusion of 6% low molecular dextran which would induce the central volume expansion, PCWP was increased [(13.0±2.0) mm Hg] when compared with that [ (10.5±2.8) mm Hg, P<0.01] before the infusion in 9 NS children in the edema phase. Most of them did not present remarkable changes in their heart rates and blood presures except for one who had increased PCWP (from 14.0 mm Hg to 16.9 mm Hg) and manifested with dysphoria, oppressed, hypertention and tachycardia. The symptoms were improved by the active diuretic treatment. Conclusions PCWP measurement with the echocardiography in NS patients could indirectly assess the plasma volume and help to work out the therapeutic strategy for the treatment of edema in NS children. Key words: Nephrotic syndrome; Pulmonary wedge pressure; Atrial natriuretic factor; Hematocrit