Effect of modified ultrafiltration on plasma thromboxane B2, leukotriene B4, and endothelin-1 in infants undergoing cardiopulmonary bypass

Background. Plasma thromboxane B2 (TXB2), leukotriene B4 (LTB4), and endoth elin-l (ET-1) levels increase on cardiopulmonary bypass (CPB). Elevated lev els of TXB2 and ET-1 have been correlated with postoperative pulmonary hype rtension in infants undergoing repair of congenital heart defects. LTB4 is a potent chemotactic cytokine whose levels correlate with leukocyte-mediate d injury. Modified ultrafiltration (MUF) has been associated with improved hemodynamics and pulmonary function, in addition to its beneficial effects on fluid balance and blood conservation. Recent investigations have suggest ed that removal of cytokines may be the cause of the improved cardiopulmona ry function seen with MUF. Methods. Plasma TXB2, ET-1, and LTB4 levels were measured in 34 infants und ergoing CPB: 22 underwent MUF (group 1), and 12 did not (group 2). Samples were obtained at various time points. All patients underwent conventional u ltrafiltration during the rewarming phase of cardiopulmonary bypass. Results. In group 1, mean end-CPB TXB2 level was 101.2 pg/mL versus 46.9 pg /mL post-MUF (p < 0.05). The mean TXB2 level 1 hour post-CPB (54.1 pg/mL) w as not significantly different from the post-MUF level. In group 2, the mea n end-CPB TXB2 level was 123.6 pg/mL versus 53.2 pg/mL 1 hour post-CPB. Hen ce, TXB2 levels decreased by similar amounts and to similar levels by 1 hou r post-CPB in both groups. ET-1 levels increased after CPB and were unaffec ted by MUF: 1.45, 1.80, 2.55 pg/mL at end-CPB, post-MUF, and 1 hour post-CP B, respectively, in group 1; and 1.51, and 2.73 pg/mL at end-CPB and 1 hour post-CPB in group 2. LTB4 levels post-MUF were 119% of pre-MUF values, and were similar at 1 hour post-CPB in both groups. Conclusions. Despite reduction in TXB2 by MUF, values were similar and appr oached baseline 1 hour post-CPB in both groups. LTB4 levels increased sligh tly with MUF. ET-1 levels increased during and post-CPB and were unaffected by MUF. MUF does not appear to have a significant effect on post-CPB level s of TXB2, ET-I, and LTB4. Therefore, the improved hemodynamics observed wi th MUF do not appear to be related to removal of these cytokines. (C) 1999 by The Society of Thoracic Surgeons.