Nuclear Medicine Technology and Other Health Applications Early Detection and Localization of Projece Title: 16. , Pulmonary Impairment RYx-01-03-(£) Expeeted Results in FY 1973: This is a new program to be initiated during FY 1975, However, some preliminary studies ac BNL have shown that stable inert helium appears to be an excellent tracer for the measurement of closing volumes, and its concentration in the exhaled air can be readily measured with the comercial helium "leak derector'', The procedure for measuring distal airway closure is based on a single-breath analysis of the expirate. A bolus of helium is introduced into the mouth of the subject, while seated erect, just after forced expiration to his residual volume (RV). The subjeet ins hales the tracer and air to his vital capacity (VC). <A bolus volume of 1 al is administered to adult males, while a smaller volume is used for female and young: male subjects. ,* All volumes are determined with a spirometer, and the helium concentration in air is measured continuously by withdrawing a small sidestream through a needle valve at the mouth of the subject during forced expiration to the Limit of the subject's RV again. The helium concentration in the sidestream is determined with a mass spectrometer of the "leak detector” type. The resultane volumes and helium concentrations are continuously recorded for the entire cycle, and a sharp upward inflection in the helium concentration is observed toward the end of a characteristically straight portion of the concentration-volume curve known as the "alveolar plateau" This inflection point, expressed as percent VC, is believed to indicate distal airway closure. The introduction of very small boluses -- one of the advanteges of using helium -- resulted in a linear increase of closing volume with age for a group of healthy non-smokers. The correlation was in good agreement with that previously reported for argon tracer, but not with those for nitrogen and xenon. Cardiogenic oscillations were greatly reduced with helium in the recorded instrument output, while background toise and statistical fluctuations were damped out by using the leak detector -in contrast to the output of regular mass spectrometers, lv, Expected Results in FY 1974: As noted above, this is a new program to be initiated during FY 1975, unless suppl ary funds are received to permit an earlier start. In the latter ec sete work described below under Section 18 will begin as soon as fundi OoOuLTS, 18. Expected Results in FY 1975: Airway closure will continue to be measured in large groups of healthy people, The subjects will be drawn mainly from the work force at BNL and patients at the associated hospital centers. Selected patients at the hospitals at BNL and off-site with known lung disorders will also be tested. (See Continuation She-2) 4479244 we ne et mm te aco ——-