The Diagnostic Importance of a Reduced FEV1/FEV6

Abstract

Background: On spirometry the FEV₁/FEV₆ ratio has been advocated as a surrogate for the FEV₁/FVC. The significance of isolated reductions in either the FEV₁/FEV₆ or FEV₁/FVC is not known. Methods: First-time adult spirograms (n = 22,837), with concomitant lung volumes (n = 12,040), diffusion (n = 14,154), and inspiratory capacity (n = 12,480) were studied. Four groups were compared. 1) Only FEV₁/FEV₆ reduced (n = 302). 2) Only FEV₁/FVC reduced (n = 1158). 3) Both ratios reduced (n = 6593). 4) Both ratios normal (n = 14,784). Results: In patients with obstructed spirometry (either a reduced FEV₁/FVC and/or FEV₁/FEV₆), 3.8% only had a reduced FEV₁/FEV₆, while 14.4% only had a reduced FEV₁/FVC. The mean FEV₁ was lower when both ratios were reduced. The group with only a reduced FEV₁/FEV₆, compared to only the FEV₁/FVC reduced, had a lower FEV₁, FVC, BMI, Expiratory Time, and IC (p values < 0.0001). DLCO was also lower (p = 0.005), and the FEV₁/FVC and RV/TLC were higher (p values < 0.0001). When the patients with only a reduced FEV₁/FEV₆ had a subsequent spirogram, 60% had a reduced FEV₁/FVC when their mean expiratory times were 3.5 seconds longer. Ninety percent of this group had strong clinical evidence of airways obstruction. Conclusions: The FEV₁/FEV₆ is not as sensitive as the FEV₁/FVC for diagnosing airways obstruction, but in the presence of a normal FEV₁/FVC, subjects have greater physiologic abnormalities than when only the FEV₁/FVC is reduced. The FEV₁/FEV₆ ratio should not replace the FEV₁/FVC as the standard for airways obstruction, but there is benefit including this measurement to identify individuals with greater air trapping and diffusion abnormalities.     

FEV1/FEV6 is effective as a surrogate for FEV1/FVC in the diagnosis of chronic obstructive pulmonary disease

Background and objectiveChronic Obstructive Pulmonary Disease (COPD) causes substantial morbidity and mortality across the globe. Diagnosis of COPD requires post-bronchodilator FEV1/FVC <0.70 as per GOLD Guidelines. FVC maneuver requires a minimum of 6 seconds of forceful expiration with no flow for 1 second for an accepted effort, which lacks any fixed cut-off point. This leads to discomfort, especially in advanced COPD and old aged population. We conducted this study to find the utility of FEV1/FEV6 as a surrogate for FEV1/FVC, the correlation between the two ratios, and the fixed cut-off value of FEV1/FEV6 for COPD diagnosis.MethodsThis was a prospective, cross-sectional study approved by the institutional ethics committee conducted from January 2017 to November 2018. Consented patients above 18 years suspected of COPD underwent Spirometry as per ATS guidelines. FEV1, FEV6, FEV1/FEV6 and FEV1/FVC ratios were recorded from the best acceptable maneuver.ResultsOut of 560 screened patients, 122 diagnosed as COPD. The correlation coefficient between the post-bronchodilator FEV1/FVC ratio and FEV1/FEV6 ratio was 0.972 (p < 0.01). The relationship between the post-bronchodilator FEV1/FVC ratio and FEV1/FEV6 ratio (linear regression analysis) was found out as: FEV1/FVC = ?1.845 + 1.009(FEV1/FEV6). Using this formula, the post-bronchodilator FEV1/FEV6 value of 71.845 was obtained corresponding to the post-bronchodilator FEV1/FVC value of 70.00.ConclusionWe found a positive correlation coefficient (r = 0.972, p < 0.001) between the FEV1/FEV6 and FEV1/FVC ratios and the cut off value of 71.845 (p < 0.01) for the post-bronchodilator FEV1/FEV6 ratio for the diagnosis of COPD. Thus FEV1/FEV6 should be used as a surrogate for FEV1/FVC for the diagnosis of COPD.     

第一秒与六秒用力呼气容积比值检测气流阻塞的临床研究

目的 探讨在肺功能测定中能否用第1秒用力呼气量与6秒用力呼气量比值（FEV1/FEV6）代替第1秒用力呼气量与肺活量比值（FEV1/FVc）的可行性.方法 对256名慢性阻塞性肺病（COPD）患者和174名非COPD患者进行肺功能检测,收集FVC、FEV6、FEV1/FVC、FEV1/FEV6等数据.比较FEV6与FVC以及FEV1/FEV6与FEV1/FVC的相关性;并以FEV1/FVC〈70%作为判断气流阻塞的标准,计算相应FEV1/FEV6检测气流阻塞的敏感性和特异性.结果 （1）FEV6与FVC以及FEV1/FEV6与FEV1/FVC均呈强正相关关系;（2）根据ROC曲线结果,取FEV1/FEV6为〈72.6%,其诊断气流阻塞的敏感性和特异性分别达到97.7%和98.4%.结论 FEV1/FEV6能够代替FEV1/FVC检测气流阻塞。     

Effect of Bilateral Lung Volume Reduction Surgery on FEV1 Decline in Severe Emphysema

Study Objective. To examine whether lung volume reduction surgery (LVRS) alters the anticipated natural rates of decline in FEV₁. Design. Retrospective analysis of spirometry results (188 studies) in patients before and after bilateral LVRS. Setting. Large, urban, academic medical center. Patients. 25 patients with severe emphysema (mean (SD) age 60 ± 8 yrs; FEV₁ 0.74 ± 0.29 L, 29% predicted). Interventions. Bilateral LVRS performed via median sternotomy, with areas targeted for resection based on preoperative evaluation using high-resolution computed tomography, quantitative perfusion scans, and intraoperative inspection of the lungs. Linear regression analysis was performed on each patient using all serial postbronchodilator FEV₁ values from before and after LVRS. Results. Lung function data were available between 2–1001 days prior to LVRS and 71–1169 days after LVRS. Comparison of single pre- and post-LVRS FEV₁ results confirmed a significant post-operative (3 month) improvement in lung function. The calculated rate of decline in FEV₁ prior to LVRS was 202 ± 205 mL/yr. Following LVRS, the rate of decline in FEV₁ was unchanged at 178 ± 150 mL/yr (p = 0.64). Conclusions. In patients with severe emphysema, bilateral LVRS does not appear to significantly alter the rate of FEV₁ decline.     

Individual FEV1 Trajectories Can Be Identified from a COPD Cohort

Objective: We aim to make use of clinical spirometry data in order to identify individual COPD-patients with divergent trajectories of lung function over time. Study Design and Setting: Hospital-based COPD cohort (N = 607) was followed on average 4.6 years. Each patient had a mean of 8.4 spirometries available. We used a Hierarchical Bayesian Model (HBM) to identify the individuals presenting constant trends in lung function. Results: At a probability level of 95%, one third of the patients (180/607) presented rapidly declining FEV₁ (mean -78 ml/year, 95% CI -73 to -83 ml) compared to that in the rest of the patients (mean -26 ml/year, 95% CI -23 to -29 ml, p ≤ 2.2 × 10^-16). Constant improvement of FEV₁ was very rare. The rapid decliners more frequently suffered from exacerbations measured by various outcome markers. Conclusion: Clinical data of unique patients can be utilized to identify diverging trajectories of FEV₁ with a high probability. Frequent exacerbations were more prevalent in FEV₁-decliners than in the rest of the patients. The result confirmed previously reported association between FEV₁ decline and exacerbation rate and further suggested that in clinical practice HBM could improve the identification of high-risk individuals at early stages of the disease.     

A literature review of the evidence that a 12% improvement in FEV1 is an appropriate cut-off for children

Introduction: A well-performed spirometry, using a change in forced expiratory volume in one second (FEV₁) after albuterol, is commonly used to support the likelihood of an asthma diagnosis. The current standard, accepted by the 2007 National Heart Lung and Blood Institute Asthma Expert Panel Report-3 (EPR-3) guidelines, is a 12% improvement in the FEV₁ after a bronchodilator. Objective: We sought to determine whether existing studies support or refute using a 12% improvement as a significant change in FEV₁ in children and adolescents. Data sources: We reviewed the literature of children and adolescents using Medline searches to discover pertinent population studies and comparative studies that included FEV₁ measurements. Result: The majority of the discovered studies suggest a less stringent improvement in FEV₁ in children might be applicable. Conclusion: Supported by the published literature, we suggest an alternative interpretive strategy of expressing the results of a spirometry measurement when a diagnosis of asthma in a child is being considered using a bronchodilator response.     

FEV1/FEV6 and FEV6 as an alternative for FEV1/FVC and FVC in the spirometric detection of airway obstruction and restriction

STUDY OBJECTIVES: To evaluate the use of the FEV(1)/forced expiratory volume at 6 s of exhalation (FEV(6)) ratio and FEV(6) as an alternative for FEV(1)/FVC and FVC in the detection of airway obstruction and lung restriction, respectively. SETTING: Pulmonary function laboratory of the Academic Hospital of the Free University of Brussels. PARTICIPANTS: A total of 11,676 spirometric examinations were analyzed on subjects with the following characteristics: white race; 20 to 80 years of age; 7,010 men and 4,666 women; and able to exhale for at least 6 s. METHODS: Published reference equations were used to determine lower limits of normal (LLN) for FEV(6), FVC, FEV(1)/FEV(6), and FEV(1)/FVC. We considered a subject to have obstruction if FEV(1)/FVC was below its LLN. A restrictive spirometric pattern was defined as FVC below its LLN, in the absence of obstruction. From these data, sensitivity and specificity of FEV(1)/FEV(6) and FEV(6) were calculated. RESULTS: For the spirometric diagnosis of airway obstruction, FEV(1)/FEV(6) sensitivity was 94.0% and specificity was 93.1%; the positive predictive value (PPV) and negative predictive value (NPV) were 89.8% and 96.0%, respectively. The prevalence of obstruction in the entire study population was 39.5%. For the spirometric detection of a restrictive pattern, FEV(6) sensitivity was 83.2% and specificity was 99.6%; the PPVs and NPVs were 97.4% and 96.9%, respectively. The prevalence of a restrictive pattern was 15.7%. Similar results were obtained for male and female subjects. When diagnostic interpretation differed between the two indexes, measured values were close to the LLN. CONCLUSIONS: The FEV(1)/FEV(6) ratio can be used as a valid alternative for FEV(1)/FVC in the diagnosis of airway obstruction, especially for screening purposes in high-risk populations for COPD in primary care. In addition, FEV(6) is an acceptable surrogate for FVC in the detection of a spirometric restrictive pattern. Using FEV(6) instead of FVC has the advantage that the end of a spirometric examination is more explicitly defined and is easier to achieve.     

Minimal Clinically Important Differences in COPD Lung Function

The FEV₁ is widely used by physicians in the diagnosis, staging, treatment, monitoring and establishing prognosis for patients with COPD. The MCID is the smallest difference which patients perceive as beneficial and which would mandate a change in patient management. A precise MCID for FEV₁ has not been established.

In attempt to establish a MCID for predose or trough FEV₁, several limitations need to be addressed. There are issues such as reproducibility, repeatability, acceptability, variability, placebo effect, and equipment effects. Patient factors, such as baseline level of FEV₁, albuterol reversibility, diurnal variation, influence the results.

Nonetheless, using anchoring techniques, a change in pre dose FEV₁ of about 100 mL can be perceived by patients, correlates with fewer relapses following exacerbations and is in the range usually achieved with bronchodilators approved for COPD.

In the future, consistent reporting of spirometric variables, such as a predose FEV₁ and other outcomes, can be incorporated into a more quantitative effort to establish the MCID. Also distributional/statistical methods may be useful in determining the MCID FEV₁.     

Fibroblast growth factor-2 is a sputum remodeling biomarker of severe asthma

Objective: Given the large phenotypic diversity of asthma, our aim was to characterize molecular profiles related to asthma severity using selected remodeling biomarkers in induced sputum. Methods: Induced sputum from healthy controls, patients with mild to moderate asthma and severe asthma were collected. Twelve selected biomarkers previously associated to airway remodeling such as connective tissue growth factor (CTGF), fibroblast growth factor (FGF)-2, matrix metalloproteinase (MMP)-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-12, MMP-13, procollagen type 1 and tissue inhibitor of metalloproteinase (TIMP)-1 were measured in sputum samples using ELISA or Luminex technology. FGF-2 level was also evaluated in bronchial biopsies using immunohistochemistry. Results: Sputum of severe asthma was characterized by reduced percentage of macrophages and increased percentage of neutrophils and eosinophils. FGF-2, MMP-1 and TIMP-1 levels increased with asthma severity. Interestingly, only FGF-2 level inversely correlated with FEV₁/FVC ratio. Although percentage of eosinophils correlated with asthma severity, it did not correlate with FGF-2 levels. Increased levels of FGF-2 with asthma severity were confirmed in bronchial biopsies by immunohistochemistry. Conclusions: Level of FGF-2 in induced sputum represents a relevant remodeling biomarker of asthma severity and significantly correlates with pulmonary function. FGF-2 sputum biomarker is proposed to reveal the phenotype of asthma characterized by fixed airflow obstruction.     

Association of Dopamine-related Gene Alleles,Smoking Behavior and Decline in FEV1 in Subjects with COPD: Findings from the Lung Health Study

Abstract

Cigarette smoking is the major risk factor for chronic obstructive pulmonary disease (COPD). Specific dopamine related gene alleles have previously been found to be associated with smoking initiation, maintenance and cessation. We investigated the association between specific dopamine related gene alleles and both change in smoking behavior and lung function change over time in individuals with mild-to-moderate COPD. Subjects included a subset of participants in the Lung Health Study (LHS), a smoking intervention study in smokers with mild to moderate COPD. Smoking status was determined and lung function performed at baseline and annually for 5 years. In post-hoc analyses, we assessed the association of the dopamine receptor (DRD2) TaqI A1⁺ allele (A1A1, A1A2 genotypes) and A1^? allele (A2A2 genotype), and the dopamine transporter (DAT) 9R⁺ allele (9R9R and 9R10R genotypes) and 9R^? allele (10R10R genotype) with both changes in smoking status and lung function in a subset of LHS subjects. No significant associations were noted between variants in these genes and success in smoking cessation. However, in exploratory analyses that did not adjust for multiple comparisons, sustained male (but not female) quitters with the DRD2 A1^? allele and/or the DAT 9R⁺ allele showed an accelerated decline in FEV₁ similar to that of continuing smokers over 5 years after quitting smoking. These preliminary findings suggest that dopamine-related genes may play a role in the progression of COPD, at least in the subset of male ex-smokers whose disease continues to progress despite sustained quitting, and warrants additional confirmatory and mechanistic studies.     

Preparation and Electrochemical Properties of LiNi2/3Co1/6Mn1/6O2 Cathode Material for Lithium-Ion Batteries

The cathode material LiNi_2/3Co_1/6Mn_1/6O₂ with excellent electrochemical performance was prepared successfully by a rheological phase method. The materials obtained were characterized by X-ray diffraction, scanning electron microscopy, electrochemical impedance spectroscopy and charge-discharge tests. The results showed that both calcination temperatures and atmosphere are very important factors affecting the structure and electrochemical performance of LiNi_2/3Co_1/6Mn_1/6O₂ material. The sample calcinated at 800 °C under O₂ atmosphere displayed well-crystallized particle morphology, a highly ordered layered structure with low defects, and excellent electrochemical performance. In the voltage range of 2.8–4.3 V, it delivered capacity of 188.9 mAh g⁻¹ at 0.2 C and 130.4 mAh g⁻¹ at 5 C, respectively. The capacity retention also reached 93.9% after 50 cycles at 0.5 C. All the results suggest that LiNi_2/3Co_1/6Mn_1/6O₂ is a promising cathode material for lithium-ion batteries.     

IL-8 Gene Variants are Associated with Lung Function Decline and Multidimensional BODE Index in COPD Patients But Not with Disease Susceptibility: A Validation Study

Background and objective: COPD is a leading cause of dead worldwide and tobacco smoking is its major risk factor. IL8 is a proinflammatory chemokine mainly involved in the acute inflammatory reaction. The aim of this study was to test the association of IL-8, CXCR1 and CXCR2 gene variants and COPD susceptibility as part of a replication study and explore the effect of these variations in disease progression. Methods: 9 tagSNPs were genotyped in 728 Caucasian individuals (196 COPD patients, 80 smokers and 452 non-smoking controls). Pulmonary compromise was evaluated using spirometry and clinical parameters at baseline and annually over a 2 years period. We also determined plasma levels of TNF-α, IL-6, IL-8 and IL-16 in COPD patients. Results: There was a lack of association between gene variants or haplotypes with predisposition to COPD. No correlation was observed between the polymorphisms and cytokines levels. Interestingly, significant associations were found between carriers of the rs4073A (OR = 3.53, CI 1.34-9.35, p = 0.01), rs2227306C (OR = 5.65, CI 1.75–18.88, p = 0.004) and rs2227307T (OR = 4.52, CI = 1.49–12.82, p = 0.007) alleles in the IL-8 gene and patients who scored higher in the BODE index and showed an important decrease in their FEV₁ and FVC during the 2 years follow-up period (p < 0.05). Conclusions: Despite no association was found between the studied genes and COPD susceptibility, three polymorphisms in the IL-8 gene appear to be involved in a worse progression of the disease, with an affectation beyond the pulmonary function and importantly, a reduction in lung function along the follow-up years.     

Predicting inadequate spirometry technique and the use of FEV1/FEV3 as an alternative to FEV1/FVC for patients with mild cognitive impairment

Introduction and Objectives: Some patients cannot perform forced vital capacity (FVC). We conducted a study to answer three questions: Can the ability to perform components of spirometry be predicted by the Mini Mental State Examination (MMSE)? What proportion of subjects can perform forced expiratory volume in 3 s (FEV3) but not FVC? Does the forced expiratory volume in 1 s (FEV1)/FEV3 ratio concord with FEV1/FVC ratio in patients with airflow obstruction? Methods: We conducted a prospective observational study of 267 patients with a mean age of 79 years, including subjects with indicators of frailty. They performed spirometry and the MMSE. Spirometric recordings were compared to the American Thoracic Society 1994 criteria. Results: FVC was achieved by 51% of patients. Inability to perform FVC was predicted by an MMSE < 24 (specificity 94%, sensitivity of 51%). An FEV1/FEV3 ratio < 80% matched a FEV1/FVC ratio < 70% (sensitivity 96%, specificity 97%). Twenty‐five percent of subjects were able to reach FEV3 but not FVC; 14% of that group had an MMSE < 24. Subjects with an MMSE < 20 were unable reliably to perform any spirometry. Conclusion: Patients with an MMSE < 24 are usually unable to reach FVC reliably when tested on a single occasion, but some can reach FEV3. Patients with MMSE < 20 cannot do spirometry. An FEV1/FEV3 ratio < 80% can be used to help identify patients with airflow obstruction if they are unable to perform full spirometry to FVC. Please cite this paper as: Allen S, Yeung P, Janczewski M and Siddique N. Predicting inadequate spirometry technique and the use of FEV1/FEV3 as an alternative to FEV1/FVC for patients with mild cognitive impairment. The Clinical Respiratory Journal 2008; 2: 208–213.     

Evaluation of Bedoradrine Sulfate (MN-221), a Novel,Highly Selective Beta2-Adrenergic Receptor Agonist for the Treatment of Asthma via Intravenous Infusion

Background. The number of hospitalizations or deaths due to asthma, most of which result from acute exacerbations of asthma, has remained the same for the past 20 years. MN-221 (bedoradrine sulfate) is a novel, highly selective beta₂- (β₂-) adrenergic agonist administered via intravenous (IV) infusion in development for the treatment for acute exacerbation of asthma. Objectives. Trial MN-221-CL-004 assessed the safety profile and preliminary efficacy of MN-221 in escalating doses in patients with stable mild-to-moderate asthma. Study MN-221-CL-005 assessed the safety profile and preliminary efficacy of MN-221 in patients with stable moderate-to-severe asthma when given as a fixed dose over 1- or 2- hr infusion. Methods. Two randomized, placebo-controlled clinical trials (n = 40) were performed to evaluate the pharmacokinetic (PK) and clinical effects of a novel, highly selective β₂-agonist, MN-221, via IV infusion. Safety evaluations included vital signs, adverse events (AEs), clinical laboratory parameters, and electrocardiogram results. Efficacy evaluation included measurement of forced expiratory volume in 1 second (FEV₁) and PK parameters were additionally monitored. The study was reviewed and approved by the Institutional Review Board at each site. Results. Adverse effects were mild or moderate and there were no serious AEs or deaths during the studies. The most frequently reported AEs were tremor, hypokalemia, and headache. There were no consistent dose-dependent effects of MN-221 on any safety parameters, with the exception of heart rate, which was not considered to be clinically significant and did not require any treatment. Moderate hypokalemia occurred once in one subject in the MN-221-CL-004 study and twice in one subject in the MN-221-CL-005 study and were transient and returned to normal range following single oral potassium chloride treatments. PK assessments indicated a linear response in MN-221 plasma concentrations for the doses evaluated. Dose escalation results showed that mean changes in FEV₁ from pre-infusion were significantly greater than placebo and an overall dose response was statistically significant (p < .0001). Post-infusion FEV₁ improvements appeared to plateau at the 30 μg/min dose level despite a higher peak plasma concentration at 60 μg/min. Dose-rate escalation results demonstrated greater mean increases in change in FEV₁ compared to the placebo group with the largest increase associated with the higher MN-221 dose rate and peak plasma concentration. Conclusions. The safety profile of MN-221 and evidence of dose- and plasma-concentration-related bronchodilation supports further clinical development and suggests the potential for clinical benefit without increased clinical risk, particularly for patients where inhaled or nebulized therapy is not adequate or possible. Trial registry name and registration number:Name: MN-221-CL-005Number: NCT00679263     

Plasma homocysteine is elevated in COPD patients and is related to COPD severity

Background:

Although recent studies have found that total plasma homocysteine (tHCY) and chronic obstructive pulmonary disease (COPD) are both risk factors for cardiac disease, there have been few studies of plasma homocysteine levels in COPD patients. We tested the hypothesis that total plasma homocysteine (tHCY) would be elevated in patients diagnosed with COPD compared with controls.

Methods:

We studied 29 COPD outpatients and 25 asymptomatic subjects (controls) over age 55 years with measurement of forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), St. Georges Respiratory Questionnaire (SGRQ) score, tHCY and serum C-reactive protein (sCRP).

Results:

There was no difference between controls vs. COPD patients in mean age or gender but mean (SD) FEV₁ was 2.25 (0.77) vs 1.43 (0.60) L; FEV₁% predicted 76.1 (17.2) vs 49.1 (16.3) p < 0.001 in both cases. Median (IQR) tHCY was 8.22 (6.63, 9.55) in controls vs 10.96 (7.56, 13.60) micromol/l for COPD, p = 0.006 and sCRP 0.89 (0.47, 2.55) vs 2.05 (0.86, 6.19) mg/l, p = 0.023. tHCY(log) was also higher in (r, p) smokers (0.448, 0.001), patients with low FEV₁% (−0.397, 0.003), males (0.475, <0.001), but high SGRQ Total score (0.289, 0.034), and high sCRP (0.316, 0.038). tHCY(log) was independently related to (regression coefficient, p) sCRP(log) (0.087, 0.024), male gender (0.345, <0.001) and presence of COPD (0.194, 0.031). Median (IQR) tHCY GOLD Stage I and II 8.05 (7.28, 11.04), GOLD Stage III and IV: 11.83(9.30, 18.30); p = 0.023.

Conclusions:

Plasma homocysteine is significantly elevated in COPD patients relative to age and sex-matched controls and is related to serum CRP and COPD severity.     

Bronchodilatation Effects of a Small Volume Spacer Used with a Metered-Dose Inhaler

Background and objective. In an effort to improve the delivery of drugs to the lungs, various spacer devices have been developed to attach to metered-dose inhalers (MDIs). The aim of the study was to determine whether use of a small volume tube spacer with MDI is associated with better bronchodilatation. Methods. We assessed bronchodilatation by measuring forced expiratory volume in 1 second (FEV₁) before and after inhalation of fenoterol 0.4 mg (2 puffs) delivered by using a MDI in four different ways: with or without a spacer alone or with a mouth rinse of 100 mL of water immediately after inhalation with or without a spacer. Results. A total of 303 patients who had a positive bronchodilator test were studied. There was no significant difference in the ΔFEV₁ (mL or %) with or without a spacer (MDI + spacer vs. MDI, mean ± SD, 365.1 ± 146.5 mL vs. 356.3 ± 131.1 mL, p = 0.696; and 21.4 ± 9.4% vs. 21.4 ± 9.5%, p = 0.968, respectively). When patients rinsed their mouth after inhalation, bronchodilatation was significantly less in those using an MDI alone compared with MDI + spacer (302.6 ± 116.5 mL vs. 367.6 ± 128.3 mL, p = 0.002; and 18.0% ± 7.9% vs. 21.7% ± 9.5%, p = 0.013, respectively). Conclusions. When patients correctly use an MDI, addition of a spacer does not significantly improve bronchodilatation. However, if the mouth is rinsed after inhalation, a spacer does yield better bronchodilatation. Our results suggest that systemic effects from bronchodilator inhalation may not be negligible.     

FEV6 as a surrogate for FVC in detecting airways obstruction and restriction in the workplace.

Compared with measurements of forced vital capacity (FVC), using the forced expiratory volume in six seconds (FEV(6)) reduces test time and frustration. It was hypothesised that using FEV(6) in the workplace setting would result in an acceptably low misclassification rate for detecting airways obstruction and spirometry-defined restriction when compared with using the traditional FVC. Experienced technicians from the National Institute for Occupational Safety and Health performed spirometry using dry rolling-seal spirometers as per American Thoracic Society guidelines in four workplace investigations. Airways obstruction was defined as an FEV(1)/FVC % below the lower limit of normal (LLN) using National Health and Nutrition Examination Survey III reference equations. Restriction was defined as an FVC below the LLN with a normal FEV(1)/FVC %. These "gold standard" definitions were compared with definitions based on FEV(6) (obstruction: FEV(1)/FEV(6) below the LLN; restriction: FEV(6) below the LLN with a normal FEV(1)/FEV(6)). The median (range) age of the 1,139 workers was 37 yrs (18-71 yrs) and 51.4% were male. A significantly high overall agreement was obtained between the two definitions. In conclusion, the current results confirm that forced expiratory volume in six seconds can be used as a surrogate for forced vital capacity in detecting airways obstruction and restriction in workers, although with some misclassification when compared to obtaining American Thoracic Society-acceptable manoeuvres of longer duration.