Abstract
To examine the validity of water removal control by the BVM of the Fresenius 4008S, an in vivo study was carried out in eight ESRD patients. Relative blood volume (RBV), defined as blood volume (BV) divided by its initial value, and blood pressure (BP) drop during treatment was examined between dialysis treatments with and without BVM of the machine. The ultrafiltration rate (UFR) define control strategy was determined as follows: we inputted the critical RBV value for each patient to the BVM based on his/her condition, and the BVM was started with twice the preset UFR value then the UFR value was reduced but not allowed to reach critical RBV after the RBV reach half the critical RBV.
In this study, an index for BV change defined as plasma refilling rate (PRR) divided by ultrafiltration rate (UFR) was newly introduced to estimate the degree of the water transfer from or to the patient's intravascular compartment. Time-averaged PRR/UFR value with BVM was obtained as 0.83±0.02, significantly higher than that without BVM of 0.72±0.03 (p<0.01 by a paired T-test) under the same total amount of ultrafiltration (UF). The RBV value during the treatment was also obtained higher in HD with BVM of 0.79±0.04 than that in the HD without BVM of 0.76±0.07 (N. S. by paired T-test). This means the UFR control by the BVM maintained higher plasma refilling during treatment due to the achievement of adequate water removal corresponding to the patient's circulation. None of the patients demonstrated a higher BV drop in the HD with BVM. The validity of the UFR control system by the BVM, thus, was verified during this study. The BVM seems to be effective for establishing “physiological dialysis”.
