Predicting diffusive alveolar oxygen transfer from carbon monoxide-diffusing capacity in exercising foxhounds

• Published in: Journal of applied physiology (1985) 2008-11, Vol.105 (5), p.1441-1447
• Main Authors: Hsia, Connie C. W, Wagner, Peter D, Dane, D. Merrill, Wagner, Harrieth E, Johnson, Robert L., Jr
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Carbon Dioxide - blood; Carbon Dioxide - metabolism; Carbon monoxide; Cardiac Output; Dogs; Exercise; Fundamental and applied biological sciences. Psychology; Hypoxia - metabolism; Hypoxia - physiopathology; Lung Volume Measurements; Lungs; Male; Microcirculation; Models, Biological; Oxygen; Oxygen - blood; Oxygen - metabolism; Physical Exertion; Pneumonectomy; Pulmonary Alveoli - blood supply; Pulmonary Alveoli - metabolism; Pulmonary Alveoli - surgery; Pulmonary Circulation; Pulmonary Diffusing Capacity; Reproducibility of Results; Respiration
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.01328.2007

1 Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; and 2 Department of Medicine, University of California, San Diego, La Jolla, California Submitted 14 December 2007 ; accepted in final form 18 August 2008 Although lung diffusing capacity for carbon monoxide (D L CO ) is a widely used test of diffusive O 2 transfer, few studies have directly related D L CO to O 2 -diffusing capacity (D L O 2 ); none has used the components of D L CO , i.e., conductance of alveolar membrane and capillary blood, to predict D L O 2 from rest to exercise. To understand the relationship between D L CO and D L O 2 at matched levels of cardiac output, we analyzed cumulative data from rest to heavy exercise in 43 adult dogs, with normal lungs or reduced lung capacity following lung resection, that were studied by two techniques. 1 ) A rebreathing (RB) technique was used to measure D L CO and pulmonary blood flow at two O 2 tensions, independent of O 2 exchange. D L CO was partitioned into CO-diffusing capacity of alveolar membrane and pulmonary capillary blood volume using the Roughton-Forster equation and converted into an equivalent D L O 2 , [D L O 2 (RB)]. 2 ) A multiple inert-gas elimination technique (MIGET) was used to measure ventilation-perfusion distributions, O 2 and CO 2 exchange under hypoxia, to derive D L O 2 [D L O 2 (MIGET)] by the Lilienthal-Riley technique and Bohr integration. For direct comparisons, D L O 2 (RB) was interpolated to the cardiac output measured by the Fick principle corresponding to D L O 2 (MIGET). The D L O 2 -to-D L CO ratio averaged 1.61. Correlation between D L O 2 (RB) and D L O 2 (MIGET) was similar in normal and post-resection groups. Overall, D L O 2 (MIGET) = 0.975 D L O 2 (RB); mean difference between the two techniques was under 5% for both animal groups. We conclude that, despite various uncertainties inherent in these two disparate methods, the Roughton-Forster equation adequately predicts diffusive O 2 transfer from rest to heavy exercise in canines with normal, as well as reduced, lung capacities. oxygen-diffusing capacity; multiple inert-gas elimination technique; rebreathing technique; Roughton-Forster relationship; lung resection; dog Address for reprint requests and other correspondence: C. C. W. Hsia, Dept. of Internal Medicine, Pulmonary and Critical Care Medicine, Univ. of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9034