The Potent Complement Stimulus of Sanguineous Versus Crystalloid Cardiopulmonary Bypass Prime during Pediatric Cardiac Surgery

<b>Background:</b> Sanguineous preparation of the cardiopulmonary bypass (CPB) circuit with allogeneic blood products is known to contain substantial complement mediator burden. This study aims to assess the longitudinal immunologic impacts during pediatric CPB. <b>Methods:</b> In this post-hoc analysis of a prospective observational cohort study, 40 pediatric patients undergoing cardiac surgery with CPB were grouped by CPB prime type indicated by standard of care (<i>sanguineous</i> vs <i>crystalloid</i>). Arterial samples were collected before CPB, after CPB initiation, and at 30-min intervals until weaning or 180 min. Luminex^® measured concentrations of 33 inflammatory mediators for time series and fold change comparison between groups. <b>Results:</b> The <i>sanguineous prime</i> group (n = 26) was younger (4.0 [0.2-6.0] versus 48.5 [39.0-69.5] months; <i>P</i> < .001) and smaller (4.9 [3.4-6.6] versus 17.2 [14.9-19.6] kg; <i>P</i> < .001) than the <i>crystalloid prime</i> group (n = 14). The <i>sanguineous</i> group had significantly more circulating complement mediators, including C3a, C3b, and C5a, and soluble adhesion molecules throughout the CPB time series (<i>P</i> < .05). TNF, IL-1α, and IL-1β were relatively static in both groups, although slightly more prominent in the <i>crystalloid</i> group (<i>P</i> < .05). IL-6, IL-10, and CXCL8 profiles were comparable between groups. <b>Conclusions:</b> Patients who receive sanguineous CPB prime have elevated complement and soluble cellular adhesion molecule burden throughout CPB, relative to a crystalloid prime. Therefore, these allogeneic preparations should be considered an immunogenic stimulus during pediatric CPB, and future innovation should focus on less inciting alternatives.