Large tidal volume mechanical ventilation induces vascular dysfunction in rats
Nin, Nás.; Valero, Jé.A.; Lorente, Jé.A.; de Paula, M.; Fernández-Segoviano, P.; Sánchez-Ferrer, A.; Esteban, Aés.
Journal of Trauma 59(3): 711-716
2005
ISSN/ISBN: 0022-5282 PMID: 16361917 Document Number: 593403
Background: Experimental studies have shown that mechanical ventilation using high tidal volumes (V-T) damages the lungs, causing pulmonary edema. We tested the hypothesis that high V-T ventilation in rats induces major vascular dysfunction.Methods: Healthy Sprague-Dawley rats, weighing (mean +/- SD) 340 +/- 15 g, were ventilated with either V-T = 9 mL/kg and positive end-expiratory pressure (PEEP) = 8 (n = 8) or V-T = 35 mL/kg and PEEP = 0 (n = 8). The high VT used in the injurious ventilation group is in the V-T range used in other studies to induce lung damage in a short period of time in rats. Lungs were removed for examination under light microscopy and vascular rings from the thoracic aorta were studied for isometric tension recording.Results: Relaxations to acetylcholine (p < 0.001) and sodium nitroprusside (p < 0.05) and contractions to norepinephrine were markedly decreased (p < 0.001) in the high V-T group, as compared with the low V-T group.Conclusion: Injurious mechanical ventilation in normal rats is associated with vascular dysfunction characterized by decreased relaxation to an endothelium-dependent vasodilator and to a nitrous oxide donor and by decreased response to norepinephrine.