The mechanisms of pain-induced pulmonary vasoconstriction: an experimental study in fetal lambs.

Background: Nociceptive stimulation induces pulmonary vasoconstriction in fetuses and newborns. The mechanism of this response is not fully understood. As the systemic hemodynamic response to pain is mainly mediated by sympathetic stimulation, we hypothesized that pain-induced pulmonary vasoconstriction results from the activation of catecholaminergic receptors.