Changes in plasma osmolality during treatment by the Extra-Corporeal Ultrafiltration Method (ECUM) (Long-term ECUM treatment of a refractory heart failure case)

Abstract

Recently, heart failure refractory to medication has been reported to respond successfully to treatment by ECUM (Extra-Corporeal Ultrafiltration Method). Controversy exists regarding the pathophysiology, indications, method, and parameters used to decide the volume to be removed and the rate of removal.A 61-year-old man was treated for advanced congestive heart failure by ECUM a total of 18 times over 4 months, and the serial changes of plasma osmolality were studied in relation to the hemodynamics and plasma antidiuretic hormone (ADH) levels. During ECUM, the plasma osmolality was measured at intervals of 1hr or 30min. The changes in plasma osmolality showed 1 or 2 peaks and the time to reach the 1st peak was dependent on the removal rate of the blood volume. The rise in plasma osmolality appeared to be affected by the fractional increase in removal rate of the blood volume. The plasma osmolality reached the 1st peak variously after 2hr at a removal rate of 610-400ml/hr, after 3 hr at 388-360ml/hr, and after 3.5hr at 320ml/hr. The rise in the plasma osmolality did not reach the normal range. After the peak of the plasma osmolality, it continued at relatively high levels until the end of ECUM. The plasma osmolality on the following morning was less than that on the morning of the ECUM treatment. The plasma ADH levels were in appropriately high in relation to his plasma osmolality before ECUM and no normalization occurred thereafter, with even higher levels than before. This indicated partial correction of the volume deficit, a slight reduction in the tonicity of the bodily water. Peaking of the plasma osmolality during hemorrhage has never been observed in healthy man or experimental animals. It is suspected that the rise in plasma osmolality can be ascribed to transient normalization of the high plasma ADH levels, since the amount of change in the plasma osmolality would be sufficiently large to change the plasma ADH.Serum creatinine concentration and BUN level in the morning after ECUM were selected as indicators which rose due to decreased renal blood flow resulting from the low cardiac output on the day of treatment. In general, the difference between the plasma osmolality before ECUM and that at the 1st peak reflected the effect of the removal of the blood volume.