Table. 3—

Alveolar nitric oxide concentration(C_alv,NO), airway wall NO concentration (J_aw,NO) and airway NO diffusing capacity (D_aw,NO) in the studied groups

Variables	Nonsmokers	Smokers-GOLD₀	GOLD_1–2	GOLD_3–4
J_aw,NO pL·s⁻¹	716.2±141.7^{#, ¶}	464.7±229.1⁺	630.3±417.7	609.4±275.0
	712.5 (645.8–786.7)	385.6 (379–550)	442.9 (422.5–838)	555.5 (457.1–761.7)
C_alv,NO ppb	1.4±0.4^{#, §, ƒ}	2.1±0.7^{§, ƒ}	3.3±0.7	3.4±0.6
	1.3 (1.2–1.5)	2.0 (1.8–2.4)	3.2 (2.8–3.6)	3.5 (3.0–3.7)
D_aw,NO pL·ppb⁻¹s⁻¹	11.0±2.5^{##, +}	11.6±3.2^{##, ¶}	15.7±5.1	15.0±5.0
	11.4 (9.8–12.3)	11.2 (10.4–12.8)	14.5 (13.1–18.2)	14.2 (12.2–17.2)

Data are presented as mean±sd and median (95% confidence intervals). GOLD: Global Initiative for Chronic Obstructive Lung Disease. ^#: p<0.0001 versus smokers with GOLD stage 0; ^¶: p<0.05 versus smokers with GOLD stage 0; ⁺: p<0.05 versus patients with GOLD stage 3–4; ^§: p<0.0001 versus patients with GOLD stage 1–2; ^ƒ: p<0.0001 versus patients with GOLD stage 3–4; ^##: p<0.05 versus patients with GOLD stage 1–2.