ALPP and serum lipopolysaccharide activity: Endotoxemia is particularly common both before and after infant cardiothoracic surgery with cardiopulmonary bypass23, 24 The inverse relationship between ALP activity and endotoxemia, as well as the ex vivo reduction in endotoxin activity with exogenous ALP supplementation, suggests that ALP plays a role in mitigating endotoxemia in children undergoing cardiopulmonary bypass.22