Neutropenia and plasma free radical reaction products during haemodialysis

To determine whether haemodialysis produces an increase in free radical activity, plasma phospholipid plus free fatty acid (PL+FFA) octadeca-9,11-dienoic acid (18:2(9,11)) and plasma thiobarbituric acid reactivity (TBAR) were measured serially during dialysis with cuprophan and polycarbonate membranes. Plasma TBAR did not change significantly during dialysis with either membrane. There was however, an increase in PL + FFA 18:2(9,11) and in the molar ratio of 18:2(9,11) to its parent compound, linoleic acid (18:2(9,12)), with both membranes, although this was most significant with cuprophan membranes. The administration of heparin to normal controls without dialysis produces a comparable rise in PL + FFA 18:2(9,11). Haemodialysis with prostacyclin anticoagulation resulted in no significant change in PL+FFA 18:2(9,11). The data indicates that the increase in PL+FFA 18:2(9,11) during haemodialysis is due to a heparin-induced rise in FFA 18:2(9,11) and is not a consequence of increased free radical activity. In contrast to animal models of systemic complement activation, we were unable to demonstrate an increase in plasma free radical activity during haemodialysis. However, this does not preclude a role for free radicals, released by activated neutrophils, in the pathogenesis of pulmonary dysfunction during haemodialysis.