Combined use of krypton 81m and 85m in ventilation studies. Chapter 6

In an attempt to obtain values of regional ventilatory turnover, inhalation studies with 81Krsup(m) (half-life 13 seconds) were repeated with 85Krsup(m) (half-life 4.4 hours). By comparing the equilibrium level reached by 85Krsup(m) it was possible to determine how nearly the short half-life isotope had reached equilibrium with the inspired concentration. Experimental procedures are described and pulmonary distributions at equilibrium are presented as numerical matrices. Two sources of error are considered, a) the need for immobility of the subject, and b) the dangers of the assumption of true equilibrium during the 85Krsup(m) procedure. (author)