How to interpret reduced FEV₁/VC ratio with normal FEV₁

¹ Unità Operativa (U.O.) Medicina Preventiva e del Lavoro, Laboratorio di Fisiopatologia Respiratoria
² U.O. Fisiopatologia Respiratoria, Dipartimento di Medicina Interna, Università di Genova, Azienda Ospedaliera Universitaria "San Martino", Genova
³ Centro di Fisiopatologia Respiratoria e dello Studio della Dispnea, Azienda Ospedaliera S.Croce e Carle, Cuneo, Italy

^* To whom correspondence should be addressed. E-mail: giovanni.barisione{at}hsanmartino.it.

	Abstract

Whether the combination of low FEV₁/VC ratio with normal FEV₁ represents a physiological variant or a sign of early airflow obstruction is unknown.

We studied 40 subjects presenting with low FEV₁/VC but FEV₁ within the range of normality predicted by ERS reference equations and 10 healthy controls. All subjects completed two questionnaires and underwent comprehensive pulmonary function testing, which included methacholine challenge and single-breath nitrogen wash-out.

According to the questionnaires, the subjects were assigned to three groups, i.e. rhinitis (n=8), bronchial asthma (n=13) and COPD (n=12). Subjects with negative responses to questionnaires were assigned to an asymptomatic group (n=7). Airway hyperresponsiveness was found in 4 subjects of the rhinitis group, all of the asthma group, 10 of the COPD group and was associated in the last two groups with signs of increased airway closure and gas trapping. Bronchodilator response to salbutamol was positive in only few individuals across groups. In the subjects of the asymptomatic group, no significant functional changes were observed, possibly suggesting dysanaptic lung growth.

In subjects with low FEV₁/VC and normal FEV₁, questionnaires on respiratory symptoms together with additional pulmonary function tests may help to clarify the nature of this pattern of lung function.