Single breath co diffusing capacity in anesthetized dogs with increased oxygen consumption

Abstract

In 10 dogs (mean weight 24.5 kg), anesthetized with morphine, chloralose and urethane, relaxed with succinylcholine and artificially ventilated with room air, the single breath method was employed to measure the CO diffusing capacity (D CO) before and after increase of O 2 consumption by 2:4-dinitrophenol. D CO was measured by an apnea of 10 see, and no corrections for inhomogeneit-ies of the lungs were applied. Before the administration of dinitrophenol D CO averaged 19.7 ml/min. mm Hg. With the highest dose of dinitrophenol used, 20 mg/kg, which had been found to increase the O 2 uptake about 7 times, D CO increased on the average by 15 %. Increased ventilation alone, with arterial P CO 2 kept constant, produced a decrease of D CO, on the average by 11%. These small changes of D CO could be attributed to effects of alveolar P O 2 upon the combination of CO with hemoglobin. Thus no evidence for changes in the diffusing conditions in the lungs during artificially increased O 2 uptake was found.