Inhaled nitric oxide induces cerebrovascular effects in anesthetized pigs

Although inhaled nitric oxide (NOi) is considered to act selectively on pulmonary vessels, EEG abnormalities and even occasional neurotoxic effects of NOi have been proposed. Here, we investigated cerebrovascular effects of increasing concentrations of 5, 10 and 50 ppm NOi in seven anesthetized pigs. Cerebral hemodynamics were assessed non-invasively by use of near-infared spectroscopy and indicator dilution techniques. NOi increased cerebral blood volume significantly and reversibly. This effect was not attributable to changes of macrohemodynamic parameters or arterial blood gases. Simultaneously, cerebral transit time increased while cerebral blood flow remained unchanged. These data demonstrate a vasodilatory action of NOi in the cerebral vasculature, which may occur preferentially in the venous compartment. (C) 2003 Elsevier Ireland Ltd. All rights reserved.