Fate of radioactive krypton (Kr⁸⁵) introduced intravenously in man

¹ Department of Medicine, Columbia University College of Physicians and Surgeons and Cardio-Pulmonary Laboratory of the First Medical and Chest Services, Columbia University Division, Bellevue Hospital, New York City

When a small volume of dissolved Kr⁸⁵ was rapidly injected into the venous circulation, only about 5% of the injected gas appeared in the systemic arteries. Further, when a similar solution was infused over a 10-minute period, the fraction reaching the systemic arteries was less than 15% of that contained in the pulmonary arterial blood. Because the problem of recirculation was minimized, an infusion of Kr⁸⁵ was used to measure continually the output of the right ventricle. The values obtained, both at rest and during steady-state exercise, agreed satisfactorily with direct Fick measurements. Although similar comparisons could not be made in the interval when flow was changing, the values measured with the Kr⁸⁵ method appeared to be of reasonable magnitude.