expired volume is obtained by increasing the nitrogen concentration from zero to the percentage of nitrogen in the alveoli. A plot of the nitrogen concentration (as a % of total gas) vs. The following describes a single-breath nitrogen test:Ī subject takes a breath of 100% oxygen and exhales through a one-way valve measuring nitrogen content and volume.
Nitrogen washout (or Fowler's method) is a test for measuring anatomic dead space in the lung during a respiratory cycle, as well as some parameters related to the closure of airways.Ī nitrogen washout can be performed with a single nitrogen breath, or multiple ones.īoth tests use similar tools, both can estimate functional residual capacity and the degree of nonuniformity of gas distribution in the lungs, but the multiple-breath test more accurately measuresĪbsolute lung volumes. Test for measuring anatomic dead space in the lung during a respiratory cycle Nitrogen washout
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