Chemoreceptor stimulation and hypoxic pulmonary vasoconstriction in conscious dogs

Abstract

Dogs with electromagnetic flow probes implanted on their left (Q̇ l) and main (Q̇ t) pulmonary arteries, catheters in their left atria and external jugular veins, and chronic tracheostomies were trained to accept Carlens dual-lumen endotracheal tubes into their tracheostomies, thus allowing separate ventilation of the two lungs. Swan-Ganz catheters were inserted through the jugular vein catheters. neumotachographs measured air flow to each lung. During bilateral ventilation with room air or O 2, Q̇ l was about 36% of Q̇ t. When the left lung was ventilated with N 2 while the right remained on O 2, Pa O 2 was above 90 mmHg and Q̇ l fell to about 25% of Q̇ t. When the left lung was ventilated with N 2 and the right with room air, Pa O 2 fell below 40 mm Hg and Q̇ l increased to control levels. This increase in perfusion of the hypoxic lung during systemic hypoxemia was not seen in dogs after surgical deafferentation of the systemic arterial chemoreceptors, indicating that stimulation of the arterial chemoreceptors may interfere with the hypoxic pulmonary vasoconstriction.