Ventilatory patterns were found to affect the length, duration, and number of phases in the multiple breath nitrogen washout process in both pneumoconiotic and normal subjects, thereby affecting the calculated Index of Alveolar Ventilation (a measure of distribution uniformity). In general, an increase in tidal volume was seen to raise the index through a lengthening and straightening of the earlier phases of the washout. The association, though significant, on the qualitative level, did not allow for predictable variations in the index. Wide index variation under resting conditions was frequently noted.
NIOSH, No. TR-60, 21 pages, 4 references