Estimation of Pulmonary Arteriovenous Shunt-Flow Using Intravenous Injections of T-1824 Dye and Kr85*

Pulmonary Ventilation-Perfusion Relations after Heart Valve Replacement or Repair in Man*

“…However, the magnitude of the postoperative impairment of oxygenation found in every patient makes it unlikely that these channels (12) are a major source of postoperative shunting. Likewise it seems difficult to conceive that other sources of the normal anatomical shunt, such as the Thebesian vessels, can contribute significantly to the observed large increases in the total physiologic shunt.…”

“…Table II shows the source of possible errors in this study and gives our own and previous workers' (12,15,(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31) estimates of the significance of these errors.…”

“…1 The anatomical shunt may be larger than 2% in certain diseased states (12). An anatomic shunt of 2% of the cardiac output is our estimate of the average anaent is present at low alveolar oxygen tensions, but is considered negligible across normal alveolar membranes at alveolar oxygen tensions exceeding 100 mm Hg (14).…”

Venous Admixture to the Pulmonary Circulation in Human Subjects Breathing 100 Per Cent Oxygen*

“…The role of diffusion impairment in the causation of arterial hypoxemia has been recently reevaluated ( 10), and a number of newer approaches have permitted a more precise definition of the distribution of ventilation-perfusion ratios and of its importance in gas exchange (11)(12)(13)(14)(15) incidence and magnitude of increased "direct" venous admixture in pulmonary disease (10,(16)(17)(18)(19). The paucity of such reports has probably been due to the lack of practical techniques for the accurate measurement of blood oxygen tension at high levels.…”

Sources of Venoarterial Admixture in Portal Hypertension*

“…As a measure of the right-to-left shunt, the T2 recovery gives an overestimation on account of the contribution to the T2 recovery caused by -"back-pressure" from the alveolar T2 tension, which builds up during the passage. This can, however, be corrected by calculation (18) or by simultaneous use of two gases with different solubilities (17).…”