title: Even distribution of 133Xe bolus inhaled at residual volume in healthy subjects.
abstract: We selected from among 46 healthy students (22 to 31-yr-old) 7 subjects (group A) in whom the normalized height of phase IV (height of phase IV/phase IIIx100), after inhaling a bolus of He at RV, was very small (10%). We compared them with 6 subjects (group B) selected on the basis of a tall phase IV (78%, A vs. P P less than 0.005). Age and height were comparable, but weight was lower (P less than 0.05) and RV/TLC ratio (but not other spirographic indices) was larger (P less than 0.025) in group A. The average amplitude of cardiac oscillations was 4 times higher in group B (P less than 0.005). He closing volume, but not closing capacity was less in group A (P less than 0.05). A bolus of 133Xe inhaled at RV was nearly uniformly distributed in group A while producing a large vertical gradient in group B. The difference between groups A and B may reflect a difference in the mechanical properties of the chest  wall leading to a less complete empting of the lung in the former group.
mesh_terms: D000328:Adult; D000367:Age Factors; D006801:Humans; D012115:Residual Volume; D012119:Respiration; D014109:Total Lung Capacity; D014980:Xenon Radioisotopes
chemical_list: D014980:Xenon Radioisotopes