Evaluation of markers to estimate volume status in hemodialysis patients: atrial natriuretic peptide, inferior vena cava diameter, blood volume changes and filtration coefficients of microvasculature.

Relationships among five markers of volume status - cardio-thoracic ratio (CTR), atrial natriuretic peptide (ANP), inferior vena cava diameter at quiet expiration (IVCe), blood volume change (Delta BV/TUF) during ultrafiltration and filtration coefficients of microvasculature (Lpst) - were investigated. Fifty stable hemodialysis patients were enrolled. The CTR was measured before hemodialysis (HD), and ultrasonic measurement of IVCe and sample collection for ANP were performed shortly after HD. Lpst and Delta BV/TUF were calculated using a CRIT-LINE monitor. Overhydrated patients determined by each marker (OVERctr, OVERivc, OVERanp, OVERlp and OVERbv) were compared. The agreement of volume status determined by each marker was assessed by kappa value, and the sensitivity and specificity of each marker to distinguish overhydrated patients were analyzed by a receiver-operating characteristic (ROC) curve. IVCe, ANP, Delta BV/TUF and Lpst, significantly correlated with each other. The correlation coefficients of Lpst with IVCe, ANP and Delta BV/TUF were higher than the others. The kappa value between ANP and Lpst was the highest. OVERanp was the highest, then OVERlp, OVERivc and OVERbv, in this order. The OVERlp and OVERivc patients were completely included in OVERanp. All patients, except one OVERbv patient, were included in OVERlp. The relatively high distinguishing ability of Lpst was demonstrated by ROC analysis. These results suggest that the determination of overhydration solely by ANP was an overestimation and by Delta BV/TUF was an underestimation. The relatively high correlation coefficients of Lpst with other markers, as well as its distinguishing ability, suggest that Lpst fluctuates in close relation to other markers.