EFFECTS OF NOREPINEPHRINE ON HUMAN PULMONARY CIRCULATION

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Abstract
The effect of norepinephrine on the pulmonary vessels was investigated in 21 patients and 1 normal subject. In 13, pulmonary vascular resistance was measured during intravenous injection of the amine a small increase over control figures was found, but was not statistically significant. It was thought that the coincident rise of pulmonary wedge pressure, by producing passive dilatation of the pulmonary vessels, obscured any vasoconstrictive action of norepinephrine. This and the potential errors in calculated pulmonary vascular resistance cast doubts on the appropriateness of this approach. Therefore, the response of pulmonary arterial and left atrial pressures, recorded continuously, to a single intravenous injection of norepinephrine, was observed in 9 patients with pure or predominant mitral stenosis. In the majority of these patients the pulmonary arterial pressure rose, preceding by 20 to 40 seconds a rise in left atrial pressure. Reasons in support of the conclusion that this early widening of the gradients between pulmonary arterial and left atrial pressures probably represented a manifestation of vasoconstriction produced by norepinephrine were discussed.