The nitrogen concentration is initially zero because the subject is exhaling the dead space oxygen they just breathed in (does not participate in alveolar exchange), and climbs as alveolar air mixes with the dead space air. 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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