British journal of anaesthesia
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Pulmonary endothelial dysfunction may occur after ischaemia-reperfusion injury and can be revealed as a reduced vasodilatory response upon administration of acetylcholine (ACh). ACh also releases the endothelium-derived vasodilator nitric oxide but direct measurements of this gas are difficult to perform in vivo. We wanted to study the effects of i.v. administration of ACh and the endothelium-independent vasodilator nitroglycerin on exhaled nitric oxide in relation to pulmonary endothelial dysfunction after open-heart surgery and cardiopulmonary bypass (CPB). ⋯ Interestingly, pulmonary vascular dysfunction after CPB was accompanied by a reduction in the exhaled nitric oxide response to nitroglycerin and lower levels of basal exhaled nitric oxide. The ACh-induced responses in exhaled nitric oxide were unchanged, which could indicate nitric oxide-independent mechanisms behind the endothelial dysfunction in this study. The possibility of using exhaled nitric oxide dynamics to investigate pulmonary endothelial dysfunction merits further studies.