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. Author manuscript; available in PMC: 2024 Jul 21.
Published in final edited form as: Lancet. 2022 Sep 5;400(10356):921–972. doi: 10.1016/S0140-6736(22)01273-9

Figure 14: Specific effective airway resistance in patients with COPD with and without airflow limitation (A); and in current and former smokers vs never smokers without airflow limitation (B) and with airflow limitation (C).

Figure 14:

Specific effective airway resistance is pathological if it is ≥1·2 kPa per s, which is further classified as mild (1·2–2·0 kPa per s), moderate (2·1–4·0 kPa per s), or severe (>4·0 kPa per s). It is higher in current or former smokers than in non-smokers, irrespective of the presence or absence of spirometrically determined airflow limitation.

COPD=chronic obstructive pulmonary disease.