Capillary leak syndrome in children with C4A-deficiency undergoing cardiac surgery with cardiopulmonary bypass: a double-blind, randomised controlled study

Capillary leak syndrome is a life-threatening complication after cardiopulmonary bypass (CPB), with an incidence of about 4–37% in children worldwide. On the basis of previous results, we undertook a randomised controlled study to investigate the priming with plasma rich in the C4A isotype of complement component 4 on the incidence of capillary leak syndrome in children with C4A deficiency. In a hospital in Wuhan, China, we randomly assigned 116 neonates, infants, and children lacking complement component C4A to receive C4A-free or C4A-rich plasma priming (n=58 each, 20 mL/kg). The primary outcome was capillary leak syndrome, identified as an increased transvascular escape rate of Evans blue dye from plasma. Concentrations of activated complement components C4 and C3, inflammatory mediators interleukin 6, interleukin 8, tumour necrosis factor (TNF) α, plasma protein, and PaO 2/F IO 2 ratios (ratio of the partial arterial pressure of oxygen to the fractional concentration of oxygen in inspired air) were measured before and 4 h after CPB. Analysis was by intention to treat. Three (5%) patients given C4A-rich plasma priming had capillary leak syndrome compared with 56 (97%) given C4A-free plasma (p