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FEV1)/Vital Capacity Ratio with Normal FEV1

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FEV1)/Vital Capacity Ratio with Normal FEV1 Eur Respir J 2009; 33: 1396–1402 DOI: 10.1183/09031936.00183708 CopyrightßERS Journals Ltd 2009 How to interpret reduced forced expiratory volume in 1 s (FEV1)/vital capacity ratio with normal FEV1 G. Barisione*, E. Crimi#, S. Bartolini#, R. Saporiti#, F. Copello*, R. Pellegrino" and V. Brusasco# ABSTRACT: The aim of the present study was to determine whether the combination of low AFFILIATIONS *Unita` Operativa (U.O.) Medicina forced expiratory volume in 1 s (FEV1)/vital capacity (VC) ratio with normal FEV1 represents a Preventiva e del Lavoro, Laboratorio physiological variant or a sign of early airflow obstruction. di Fisiopatologia Respiratoria, We studied 40 subjects presenting with low FEV1/VC, but FEV1 within the range of normality #U.O. Fisiopatologia Respiratoria, predicted by European Respiratory Society reference equations, and 10 healthy controls. All Dipartimento di Medicina Interna, subjects completed two questionnaires and underwent comprehensive pulmonary function Universita` di Genova, Azienda Ospedaliera Universitaria ‘‘San testing, which included methacholine challenge and single-breath nitrogen wash-out. Martino’’, Genova, and According to the questionnaires, the subjects were assigned to three groups, i.e. rhinitis (n58), "Centro di Fisiopatologia Respiratoria bronchial asthma (n513) and chronic obstructive pulmonary disease (COPD; n512). Subjects e dello Studio della Dispnea, Azienda with negative responses to questionnaires were assigned to an asymptomatic group (n57). Ospedaliera S.Croce e Carle, Cuneo, Italy. Airway hyperresponsiveness was found in four subjects of the rhinitis group, all of the asthma group, and 10 of the COPD group; in the last two groups, it was associated with signs of increased CORRESPONDENCE airway closure and gas trapping. Bronchodilator response to salbutamol was positive in only a G. Barisione few individuals across groups. In the asymptomatic group, no significant functional changes were U.O. Medicina Preventiva e del Lavoro observed, possibly suggesting dysanaptic lung growth. Laboratorio di Fisiopatologia In subjects with low FEV1/VC and normal FEV1, questionnaires on respiratory symptoms Respiratoria together with additional pulmonary function tests may help to clarify the nature of this pattern of Azienda Ospedaliera Universitaria lung function. San Martino Largo Rosanna Benzi 10 16132 Genova KEYWORDS: Atopic rhinitis, bronchial asthma, chronic obstructive pulmonary disease, dysanap- Italy tic lung growth, methacholine challenge, single-breath nitrogen wash-out Fax: 39 105556667 E-mail: giovanni.barisione@ hsanmartino.it he assumption that a decrease in forced The present study was designed to investigate Received: expiratory volume in 1 s (FEV1) and its ratio whether a careful assessment of respiratory symp- December 03 2008 T to vital capacity (VC) below the fifth percentile toms, combined with tests sensitive to abnormal- Accepted after revision: of the predicted normal value indicates an obstruc- ities of airway function, may help to interpret the January 19 2009 tive pulmonary abnormality is a useful simple pattern of low FEV1/VC ratio with normal FEV1. approach [1]. However, in some individuals with For this purpose, 40 subjects were studied who VC normal or higher than normal, the FEV1/VC ratio presented with an FEV1/VC ratio below and an STATEMENT OF INTEREST A statement of interest for may lie below the normal range while the FEV1 is still FEV1 above their lower limits of normality accord- V. Brusasco can be found at above the lower limit of normality [2–5]. Whether this ing to the European Respiratory Society (ERS) www.erj.ersjournals.com/misc/ spirometric pattern represents a physiological var- predicting equations [13]. Symptoms were assessed statements.dtl iant, possibly due to dysanaptic lung growth [6–8], or by questionnaires and lung function by additional an early sign of airflow obstruction, possibly due to tests, including measurement of lung volumes, increased airway resistance [9] or loss of elastic recoil single-breath diffusing capacity of the lung for [10],isunknown.Asthetreatmentofobstructive carbon monoxide (DL,CO), bronchodilator response pulmonary diseases is based on proper recognition of to salbutamol, methacholine (MCh) bronchial airflow obstruction [11, 12], the interpretation of this challenge and single-breath nitrogen wash-out functional pattern is of practical relevance. (SBN2W-O). European Respiratory Journal Print ISSN 0903-1936 This article has supplementary material accessible from www.erj.ersjournals.com Online ISSN 1399-3003 1396 VOLUME 33 NUMBER 6 EUROPEAN RESPIRATORY JOURNAL G. BARISIONE ET AL. REDUCED FEV1/VC RATIO WITH NORMAL FEV1 MATERIALS AND METHODS achieved (maximal expiratory manoeuvre) [22, 23]. Then, Subjects without coming off the mouthpiece, they resumed tidal Forty consecutive Caucasian subjects presenting with an breathing and performed a slow inspiratory VC (IVC) FEV1/VC ratio below the lower limit of normality and FEV1 manoeuvre. From this set of manoeuvres functional residual within the ERS predicted normal range [13] were recruited capacity, TLC, residual volume (RV), and maximal (V9max) and from 1,386 workers (1,136 males and 250 females, 76% white- partial (V9part) forced expiratory flows at 40% control FVC collar workers) referred to the Unit of Preventive and were measured (fig. 1) [24]. The reported value of FEV1/VC is Occupational Medicine of San Martino University Hospital the one calculated by using the largest of the technically (Genoa, Italy) to be spirometrically tested for pre-employment acceptable IVCs or FVCs [19]. or surveillance purposes. Of the remaining subjects, 1,269 showed a normal spirometry, 72 an obstructive and five a An SBN2W-O test [25] was performed by using a Vmax22D restrictive abnormality confirmed by lung volume measure- (VIASYS-SensorMedics Inc.). After at least four regular ments. None of the 40 subjects suffered from known breaths, the subjects were asked to fully expire to RV and cardiopulmonary or systemic diseases. 10 healthy volunteers then to take an IVC of 100% oxygen. This was followed, with both FEV1/VC and FEV1 within the normal range were without breath-hold, by a full expiration to RV at a rate of 0.30– -1 recruited from the hospital staff to serve as control group. The 0.50 L?s . Expiratory nitrogen concentration was plotted study was approved by the institutional ethics committee of against VC and the slope of nitrogen alveolar plateau (phase San Martino University Hospital and written informed consent III) calculated by drawing the best-fit line. The first departure was obtained prior to the study. from this straight line exceeding cardiogenic oscillations was taken as the onset of phase IV. The open capacity (OC) was Study design calculated as the difference between TLC and the volume at At the first visit, the selected subjects completed two which phase IV (closing capacity) began [26]. The slope of questionnaires (see online supplementary material). One was phase III and OC were measured at least in triplicate, and the administered by an occupational physician and focused on mean value retained for analysis. The results were expressed work-related air pollution [14] and habitual physical activity as % predicted (% pred) [25]. [15]; the other was self-administered and focused on symp- toms of atopic rhinitis, bronchial asthma [16, 17] and chronic MCh challenge obstructive pulmonary disease (COPD) [18]. A total score was Aerosols of MCh chloride solutions (0.2%, 1% and 6%) were computed for each disease by grading symptoms according to delivered via a DeVilbiss 646 nebuliser attached to a KoKo their temporal frequency. Grading ranged from 0 to 30 for (Rosenthal–French) breath-activated dosimeter (Ferraris, asthma, 0 to 6 for COPD and 0 to 9 for atopic rhinitis, with the Louisville, CO, USA). Aerosols were inhaled during quiet higher numbers indicating higher frequency. Control subjects tidal breathing in the sitting position [27]. Increasing doses of (with normal FEV1/VC ratio and FEV1) showed a total score MCh from 40 to 4,800 mg were inhaled until a decrease of FEV1 equal to zero for all the three sections of the self-administered o20% from control was achieved. FVC, FEV1, V9max and V9part questionnaire. Subjects with a score f2 for all questionnaire were measured only once at each step to avoid the effects of sections were assigned to an asymptomatic group, subjects full lung inflation on airway calibre. The provocative dose of with a score o3 for asthma to an asthma group, smokers MCh causing an FEV1 decrease of 20% (PD20) was determined o20 pack-yrs and a score o3 for COPD to a COPD group, and by interpolating between two adjacent points of the log dose– , subjects with scores o3 for rhinitis but 3 for asthma and response curve. If the FEV1 decrease was ,20% of control, the COPD to a rhinitis group. Absolute lung volumes and spirometry were measured before 8 and after inhaling 400 mg of salbutamol through a valved- holding chamber [19]. Approximately 1 week after the first visit, the subjects underwent a bronchial challenge with MCh. 4 Lung function measurements -1 Standard spirometry was obtained by a mass flowmeter 0 (VIASYS-SensorMedics Inc., Yorba Linda, CA, USA) with numerical integration of the flow signal [19]. DL,CO was Flow L·s measured (Vmax22D; VIASYS-SensorMedics Inc.) at least in -4 duplicate [20]. Absolute lung volumes were measured by a transmural whole- body plethysmograph (V62J; VIASYS-SensorMedics Inc.) [21]. -8 Following thoracic
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