The assessment of fluid status in haemodialysis patients: usefulness of the Doppler echocardiographic parameters

BACKGROUND: In end-stage renal disease (ESRD) patients undergoing regular haemodialysis (HD), the maintenance of fluid status within an optimal range is critical. We therefore examined the role of Doppler echocardiographic parameters in the assessment of fluid status in these patients. METHODS: Three study groups were enrolled: 40 healthy volunteers (NTNR), 40 HD patients who were normotensive without receiving antihypertensive agents (NTHD) and 38 HD patients who had remained hypertensive (HTHD) despite antihypertensive treatment. Measurements of Doppler echocardiographic parameters from pulmonary vein (PV) and mitral inflow (Mi) were performed on a non-dialysis day. Extracellular water as a percentage of body weight (ECW%) and pre-dialysis mean blood pressure (BDMBP) were references for fluid status. The best Doppler parameter for fluid status assessment identified from the study groups was then tested in another validation groups (38 NTHD and 38 HTHD). RESULTS: Among all of the PV and Mi parameters, the S/D ratio (peak systolic velocity divided by peak diastolic velocity) was correlated with fluid status parameters best (with ECW%, r = -0.49, P<0.001; with BDMBP, r = -0.51, P<0.001). The correlations were independent of age, sex and Mi parameters. The receiver operating characteristics curve analysis demonstrated that an S/D ratio >1.33 had a sensitivity of 90% and a specificity of 77% in identifying NTHD patients. When the same criterion was applied to the validation groups, the positive predictive value was 64% and the negative predictive value was 86%. CONCLUSION: The Doppler-derived S/D ratio is a potentially useful marker for the assessment of fluid status in HD patients.