The Pulmonary Circulation Following Pneumothorax and Vagotomy in Dogs

Induction of pneumothorax in anesthetized dogs with a volume of air equal to the functional residual capacity does not lead to any immediate change in pulmonary artery or vein pressures or the pressure gradient. Cardiac output drops and pulmonary vascular resistance is elevated. This change in pulmonary resistance is essentially unaffected by vagotomy and is likely a mechanical effect of decreasing lung volume. Vagotomy alone leads to a decrease in cardiac output and an increase in pulmonary vascular resistance, possibly also because of mechanical effects.