Abstract
Blood priming is required for extracorporeal continuous renal replacement therapy in neonates. However, blood is thought to release the hypotension-inducing agent bradykinin while passing through the polyacrylonitrile membranes used as low-volume hemofilters under acidic conditions. We examined bradykinin generation in blood-primed circuits and determined the performance of different purification modalities. Bradykinin was measured at 5-min intervals without blood purification in a closed circuit (n=3). Thereafter, the blood was purified using hemodialysis (dialysate flow rate, 2 L/h), hemofiltration (filtration rate, 0.5 L/h) or hemodiafiltration (dialysate flow and filtration rates, 1.5 and 0.5 L/h, respectively). Bradykinin, pH, bicarbonate, electrolytes and citric acid were measured at defined intervals during these processes (n=6). The bradykinin concentration significantly increased from 42.6 ± 12.4 to 145.0 ± 9.5 pg/mL (means ± SD) after blood priming and decreased in all modalities, but fell below 100 pg/mL at 30 min in all purifications using hemodiafiltration. The residual ratio of bradykinin at 10 min of blood purification was significantly lower in hemodiafiltration than in hemodialysis. Hemodialysis and hemodiafiltration were superior to hemofiltration in terms of other measured parameters. Hemodiafiltration might eliminate bradykinin more effectively from blood-priming circuits with polyacrylonitrile membranes than either hemodialysis or hemofiltration.
