BackgroundImmunosuppression after surgery is associated with postoperative complications, mediated in part by catecholamines that exert anti-inflammatory effects via the β-adrenergic receptor. Phenylephrine, generally regarded as a selective α-adrenergic agonist, frequently used to treat perioperative hypotension. However, phenylephrine may impair host defence through affinity.MethodsHuman leuk...