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Figure 1 | Respiratory Research

Figure 1

From: Clinical patterns in asthma based on proximal and distal airway nitric oxide categories

Figure 1

Schematic of two-compartment model and four eNO categories. A) During exhalation of nitric oxide (eNO), a steady state mean distal airway/alveolar concentration (CANO, ppb) enters the conducting airway compartment (net transfer is convection minus diffusion) where upon additional NO is transferred from the proximal airway walls (J'awNO, nl/s). CANO represents the respiratory region of the lungs (Weibel generations 17-23). J'awNO represents the larger conducting airway region of the lungs (Weibel generations 1-16), and considers the increasing surface area per unit volume of the airway tree (i.e., trumpet shape). [T: trachea; TB: terminal bronchiole; RB: respiratory bronchiole; AS: alveolar sac]. B) J'awNO and CANO can be selectively elevated (thick gray shading) and may independently characterize proximal and distal lung inflammation, creating four eNO categories: Type I, normal J'awNO and normal CANO; Type II, elevated J'awNO and normal CANO; Type III, elevated J'awNO and elevated CANO; and Type IV, normal J'awNO and elevated CANO.

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