Measurement of relative plasma volume and plasma refilling rate during ultrafiltration of hemodialysis by measuring apparatus of plasma colloidal osmotic pressure

BACKGROUND: The objective of this study is the prevention of unexpected hypotension during hemodialysis caused by unsuitable filtration rate. METHODS: The plasma colloidal osmotic pressure (COP) was measured continuously during ultra-filtration, and relative plasma volume (%PV) and plasma refilling rate (PRR) were calculated during 12 ECUMs and one dialysis on twelve patients in early stage of chronic renal failure. Values of %PV and PRR calculated from COP were drawn in graphic curves, and analysed to obtain characteristic pattern. Minimum value of %PV (%PV min), maximum value of PRR (PRRmax) and time for PRR to decrease to 95% (95% PVt) on the curves were documented simultaneously. RESULTS: At the initial stage of %PV curve, obvious fall was observed on 6 of 13 estimation (initial fall of %PV). On the contrary at the initial stage of PRR curve, obvious rise was observed on 5 estimation (initial rise of PRR). A close relationship was indicated between the two phenomenons. In 6 cases with initial fall of %PV and in 5 cases with initial rise of PRR body weight, PRRmax and 95%PVt were lower than another cases without it. The ultra-infiltration velocity was estimated to be relatively high in these groups. In these 8 cases, filtrated water volume was judged as adequate clinically. In 4 of 5 cases without final fall of PRR, it was judged as inadequate and needed to evacuate more 0.9 to 3.0 kg (average of 1.8 +/- 1.07) of water from the patients. CONCLUSIONS: From the above, we concluded that our method is useful for deciding suitable velocity of ultrafiltration and dry weight in hemodialysis therapy.)