Comparison of FEV6 and FVC for detection of airway obstruction in a community hospital pulmonary function laboratory

The National Lung Health Education Program recommends that primary care providers perform spirometry tests on cigarette smoking patients 45 years or older in order to detect airways obstruction and aid smoking cessation efforts [Ferguson GT, Enright Pl, Buist AS, et al. Office spirometry for lung health assessment in adults: a consensus statement from the national lung education program. Chest 2000; 117: 1146-61]. An abbreviated forced expiratory maneuver that requires exhalation for 6s (FEV6) has recently been proposed as a substitute for forced vital capacity (FVC) to facilitate performance of such spirometry. We set out to assess the accuracy of diagnosis of obstruction and abnormal pulmonary function using FEV6 in comparison to FVC in a community hospital population. One hundred pulmonary function tests performed at a community hospital were randomly selected and retrospectively analyzed. Sixty-three of the 100 tests had satisfactory 6-s expiration and were subject to further analysis. We compared the spirometric interpretation using Morris predictive equations for FEV1/FVC and Hankison predictive equations for FEV1/FVC and FEV1/FEV6. The Hankison set of equations is the only published reference formulas for prediction of FEV6. We found that versus our Morris gold standard, Hankison based FEV1/FVC interpretation was 100% sensitive and 67% specific for the diagnosis of obstruction and 100% sensitive and 65% specific for the diagnosis of any abnormality. The Hankison based FEV1/FEV6 interpretation was 97% sensitive and 47% specific for diagnosing obstruction and 100% sensitive and 50% specific for identifying any abnormality versus the Morris FVC based gold standard. In conclusion, in our hospital based pulmonary function laboratory, FEV6 based interpretation has excellent sensitivity for detection of spirometric abnormalities. However, its moderate specificity may hinder its utility as a screening test. Further testing is necessary to determine its reliability in different patient populations with less highly trained operators.     

Chronic respiratory symptoms, von Willebrand factor and longitudinal decline in FEV1

Although some risk factors for accelerated decline in forced expiratory volume in 1 s (FEV1) such as cigarette smoking, are well defined, it is not possible to identify those individuals with the most rapid rates of decline. Von Willebrand factor (vWF) is a product of both the pulmonary and systemic endothelium, and serum levels are raised during episodes of acute bronchitis. We hypothesized that raised serum levels of vWF may indicate sub-clinical pulmonary injury and so may predict subsequent accelerated decline in FEV1. The aims of this study were 1. to define the prevalence of chronic respiratory symptoms and obstructive airway disease in an inner-city British population and 2. to determine whether elevated levels of von Willebrand factor (vWF) identify those individuals at risk for more rapid decline in FEV1 over time. In 1987, all 2013 individuals aged 45 to 74 years at an inner-city general practice were mailed a respiratory symptom questionnaire. One in six of the responders were asked to attend for spirometry and for assessment of serum vWF. In 1996, those individuals who had spirometry and vWF assessed in 1987 were traced, and repeat spirometry was performed. In 1987, 1527 of 2013 (75.8%) individuals completed the questionnaire. Forty-two point two percent of responders reported shortness of breath on hills, 34.7% reported wheeze and 31.6% reported mucus hypersecretion. Smokers were more likely to report these symptoms. Two hundred and ten of the 251 (84%) individuals approached had spirometry and vWF assessed. Eleven percent of these had both an FEV1 < 75% predicted and a forced expiratory ratio (FEV1 forced vital capacity (FVC)) < 70%. Sub-normal spirometry was associated with wheeze, mucus hypersecretion, cigarette smoking and increasing age. By 1996, 32 (15%) of the original group of 210 individuals had died, and 117 of the remaining 178 (66%) had spirometry repeated. FEV1 < 75% predicted was a strong predictor of interim mortality, independent of age, sex and smoking history. The average decline in FEV1 was 46.7 ml yr-1. There was no significant correlation between serum vWF levels and subsequent decline in FEV1. Chronic respiratory symptoms and spirometric evidence of airflow limitation are common in inner-city residents of the U.K., and are associated with smoking history. Much of this disease is unrecognised by health professionals. An FEV1 < 75% predicted is a strong independent predictor of subsequent mortality. The measurement of serum vWF levels is unhelpful in identifying those individuals at increased risk of accelerated decline in FEV1.     

Estimating FVC from FEV2 and FEV3: assessment of a surrogate spirometric parameter

BACKGROUND: In the context that accurate measurement of FVC is important in diagnosing airflow obstruction and in assessing restriction, strategies to achieve reliable and accurate FVC measurement have drawn much attention. OBJECTIVES: Because the rate of achieving end-of-test criteria during spirometry has been shown to be low, with resultant under-recording of the FVC, the current study proposes a regression equation for estimating FVC from measured values of the forced expiratory volume in 2 s (FEV2) and forced expiratory volume in 3 s (FEV3). METHODS: The predictive equation for the estimated FVC from volume measurements within the first 3 s of exhalation (estimated FVC3) was generated based on 330 consecutive acceptable spirograms performed in the Cleveland Clinic Foundation Pulmonary Function Laboratory. The equation was applied to an independent validation set comprised of spirometry measurements on 370 different consecutive patients. RESULTS: In the validation spirometry sample, in which the prevalence of obstruction was 34% (based on values of the measured FEV1/FVC compared to National Health and Nutrition Examination Survey III values), the sensitivity, specificity, and positive and negative predictive values of FEV1/estimated FVC3 for obstruction were 93.8%, 89.1%, 81.2%, and 96.9%, respectively. The misclassification rate was 9.2%. In the same cohort, the mean difference (+/- SD) between estimated FVC3 and measured FVC was 24.7 +/- 237 mL. CONCLUSIONS: Given that FVC is frequently under-recorded, with resultant overestimation of FEV1/FVC and underdiagnosis of airflow obstruction, we believe that estimating FVC from FEV2 and FEV3 can offer practical diagnostic advantages.     

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.     

Spirometry, rapid FEV1 decline, and lung cancer among asbestos exposed heavy smokers

We assessed whether spirometric measurements are associated with the development of accelerated FEV(1) decline and lung cancer among active and previous smokers with a wide range of lung function. Bivariate and multivariate analyses that adjusted for age, intervention arm, smoking status at enrollment and smoking history, years exposed to asbestos, and evidence of asbestosis were used to assess whether baseline FEV(1) and FEV(1)/FVC ratio were associated with accelerated FEV(1) decline and incident lung cancer. The 3,041 participants enrolled from 1985 to 1994 were followed through April 30, 2005. Baseline FEV(1)/FVC ratio<0.7 was significantly associated with an increased risk for rapid lung function decline (OR=1.73; 95% CI 1.31-2.28; p<0.001). Baseline FEV(1)/FVC ratio<0.7 was also significantly associated with an increased risk of developing lung cancer, even when baseline FEV(1) was >80%. Lung cancer risk among participants with baseline airflow obstruction and FEV(1)<60% was 4-fold higher than participants without baseline airflow obstruction and FEV(1)>80% (p<0.001), even among former smokers. These data indicate an FEV(1)/FVC<0.7 among smokers is significantly associated with faster airflow loss, and an increased risk for developing lung cancer, even among those individuals with a normal FEV(1).     

The FEV1/FEV6 ratio is a good substitute for the FEV1/FVC ratio in the elderly.

AIMS: To determine the agreement between the FEV1/FEV6 ratio and the FEV1/FVC ratio in an elderly population. METHOD: The study sample consisted of 3874 participants in a cross-sectional population survey in Troms?, Norway, aged 60 years or more, in whom acceptable spirometry had been obtained. Mean differences between the FEV1/FEV6 ratio (%) and the FEV1/FVC ratio (%) were calculated according to age, sex, smoking habit, and the degree of airflow limitation. ROC-curve analysis and Kappa-statistics were used to estimate the utility of the FEV1/FEV6 ratio in predicting an FEV1/FVC ratio < 70%. RESULTS: The mean difference between FEV1/FEV6% and FEV1/FVC% was 2.7% in both men and women. The difference between the two measures increased somewhat with increasing age, and was more pronounced with smoking and decreasing FEV1/FVC ratio. The value for the FEV1/FEV6 ratio which best predicted an FEV1/FVC ratio of 70%, was 73%, and a very good agreement was found between these two cut-off values (kappa = 0.86). CONCLUSION: The FEV1/FEV6 ratio appears to be a good substitute for the FEV1/FVC ratio in an elderly population.     

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.     

Hormone replacement therapy is associated with higher FEV1 in elderly women

Estrogen and progesterone use have been associated with improved pulmonary function in premenopausal women. However, little research has examined the relationship between hormone replacement therapy (HRT) and pulmonary function in postmenopausal women. We examined the relationship of HRT with spirometry in 2,353 women aged 65 yr and older participating in the Cardiovascular Health Study in 1993/1994. Current use of HRT was hypothesized to be associated with higher FEV1, higher FVC, and less pulmonary obstruction (FEV1/FVC < 65%). FEV1 was higher among current HRT users compared to noncurrent users in the following groups: overall (1.82 L versus 1.66 L, p < 0.0001), among women without asthma (1.85 L versus 1.69 L, p < 0.0001), among former smokers (1.76 L versus 1.60 L, p = 0.013), and among never smokers (1.90 L versus 1.72 L, p < 0.0001). Overall, HRT use was associated with a lower prevalence of pulmonary obstruction (OR 0.75 [95% CI 0.55, 0.99]). After controlling for potential confounders, HRT use was significantly associated with higher FEV(1) (p = 0.031) and with a lower prevalence of obstruction (OR 0.67 [95% CI 0.48, 0.95]). We conclude that postmenopausal women who use HRT have higher levels of FEV1 and less obstruction, which could not be explained by their lower rates of smoking and other health factors associated with HRT use.     

Decline in FEV1 in relation to incident chronic obstructive pulmonary disease in a cohort with respiratory symptoms

Data on the relationship between decline in lung function and development of COPD are sparse. We assessed the decline in FEV1 during 10 years among subjects with respiratory symptoms by two different methods and evaluated risk factors for decline and its relation to incident Chronic Obstructive Pulmonary Disease, COPD. A cross-sectional postal questionnaire was in 1986 sent to 6610 subjects of three age strata. All subjects reporting respiratory symptoms were invited to a structured interview and spirometry. A follow-up survey was performed 10 years later, and totally 1109 subjects performed spirometry in both 1986 and 1996. COPD was defined according to the ATS/ERS standards (FEV1/FVC < or =0.70). The decline in FEV1 was 39 ml/year in men vs. 28 ml/year in women, p = < 0.001 (-1.53 vs. -0.12 change in percent of predicted normal value over 10 years (pp), p = 0.023), among smokers 39 vs. non-smokers 28 ml/year, p < 0.001 (-3.30 vs. 0.69 pp, p < 0.001), in subjects with chronic productive cough 36 vs. not 32 ml/year, p = 0.044 (-2.00 vs. -0.02 pp, p = 0.002). Incident cases of moderate COPD (n = 83) had a decline of 62 ml/year (-12.6 pp) and 22.9% of them had a decline > 90 ml/year (-27.8 pp over 10 years). Gender-specific analysis revealed that smoking was a stronger risk factor in women than in men, while higher age was a significant risk factor in men only. In conclusion, decline in FEV1 was associated with age, smoking, and chronic productive cough, but the risk factor pattern was gender-dependent. Among incident cases of COPD the decline was steeper and close to a quarter had a rapid decline.     

The use of microspirometry in detecting lowered FEV1 values in current or former cigarette smokers

AIMS: COPD is an underdiagnosed disease. This study was undertaken to assess the value of microspirometry in detecting reduced FEV1 values in cigarette smokers, i.e., subjects at high risk for COPD. METHODS: A total of 611 smokers or ex-smokers with a smoking history >20 years and no previously-diagnosed lung disease were recruited (389 male, age 27-83 years, mean age 56 years, mean smoking history 35 pack years, 19% ex-smokers). RESULTS: An FEV1 < 80% predicted on microspirometry was found in 44.6% of cases. The mean FEV1 was 2.8 litres (80.6% predicted, range 26-121%). This correlated well with values obtained from full spirometry (R=0.965, p<0.0001). Detailed questionnaire responses revealed that almost half of the subjects (48.2%) reported chronic cough and sputum production and 39.8% reported breathlessness during exercise. CONCLUSIONS: Microspirometry finds a considerable number of smokers or ex-smokers with reduced FEV1 values. Microspirometry is quick to perform. All smokers with reduced microspirometry FEV1 values would benefit from smoking cessation, and all patients with reduced FEV1 values need to be considered for full spirometry to confirm if they actually have 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。     

Advantages of late expiratory relaxation during maximal forced expiratory maneuver

A modification of the maneuver for the maximal expiratory flow volume (MEFV) curve was described recently to improve the rate of achieving the acceptability criteria of the American Thoracic Society. The maneuver allows the subject to relax in the later part of expiration. The present study was carried out to determine if the modified spirometry technique offered any advantages over the standard FVC maneuver in asthma patients with a wide range of airways obstruction. MEFV curves were obtained in seventy-two subjects with standard and modified procedures in a randomized, crossover design. The patients were divided into four groups depending on the degree of airways obstruction-normal spirometry, mild, moderate and severe airways obstruction. The spirometric parameters (FVC, FEV1, FEV/FVC ratio, FET, PEFR and F25-75) were compared in each group. The modified technique gave a higher FVC measurement especially in patients with moderate and severe airways obstruction along with increased FET. PEFR and FEV1 were not different between the techniques. FEV1/FVC ratio was significantly decreased in patients with moderate and severe airways obstruction. Both the techniques gave equally acceptable and reproducible results with similar variability for FEV1 and FVC. It was concluded that the modification of the standard FVC maneuver by allowing the subject to relax in the later part of expiration is advantageous as it yields a lower FEV1/FVC ratio without affecting the FEV1, has the same within-session variability and is less strenuous.     

Predictors of loss of lung function in the elderly: the Cardiovascular Health Study

Pulmonary function, as measured by spirometry (FEV1 or FVC), is an important independent predictor of morbidity and mortality in elderly persons. In this study we examined the predictors of longitudinal decline in lung function for participants of the Cardiovascular Health Study (CHS). The CHS was started in 1990 as a population-based observational study of cardiovascular disease in elderly persons. Spirometry testing was conducted at baseline, 4 and 7 yr later. The data were analyzed using a random effects model (REM) including an AR(1) error structure. There were 5,242 subjects (57.6% female, mean age 73 yr, 87.5% white and 12.5% African-American) with eligible FEV1 measures representing 89% of the baseline cohort. The REM results showed that African-Americans had significantly lower spirometry levels than whites but that their rate of decline with age was significantly less. Subjects reporting congestive heart failure (CHF), high systolic blood pressure (> 160 mm Hg), or taking beta-blockers had significantly lower spirometry levels; however, the effects of high blood pressure and taking beta-blockers diminished with increasing age. Chronic bronchitis, pneumonia, emphysema, and asthma were associated with reduced spirometry levels. The most notable finding of these analyses was that current smoking (especially for men) was associated with more rapid rates of decline in FVC and FEV1. African-Americans (especially women) had slower rates of decline in FEV1 than did whites. Although participants with current asthma had a mean 0.5 L lower FEV1 at their baseline examination, they did not subsequently experience more rapid declines in FEV1.     

Smoking cessation--but not smoking reduction--improves the annual decline in FEV1 in occupationally exposed workers

INTRODUCTION: Individuals exposed both to cigarette smoke and respiratory pollutants at work incur a greater risk of development of airway hyperresponsiveness (AHR) and accelerated decline in forced expiratory volume in 1 s (FEV1) than that incurred by subjects undergoing each exposure separately. We examined whether smoking cessation or smoking reduction improves AHR and thereby slows down the decline in FEV1 in occupationally exposed workers. METHODS: We examined 165 workers (137 males and 28 females) participating in a smoking cessation programme. Nicotine tablets were used for smoking cessation or smoking reduction. Respiratory symptoms were assessed by questionnaire, FEV1 by spirometry and AHR by methacholine challenge test. At 1 year, subjects were classified into quitters, reducers, or continuing smokers. RESULTS: Sixty-seven subjects completed the study (32 quitters; 17 reducers; 18 continuing smokers). Respiratory symptoms improved markedly in quitters (P<0.001 for all comparisons) and less so in reducers (P values between 0.163 and 0.027). At 1 year, FEV1 had slightly but significantly improved in quitters (P=0.006 vs. smokers; P=0.038 vs. reducers) and markedly deteriorated in reducers and continuing smokers. Concurrent, 1-year change in AHR did not differ significantly among the groups. CONCLUSION: In occupationally exposed workers, stopping smoking markedly improved respiratory symptoms and, in males, slowed the annual decline in FEV1. Smoking reduction resulted in smaller improvements in symptoms but deterioration in FEV1. These findings were independent of AHR. While smoking cessation should remain the ultimate goal in workplace cessation programmes more studies are necessary to better ascertain the benefits of smoking reduction.     

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.     

Can airway obstruction be estimated by lung auscultation in an emergency room setting?

OBJECTIVE: Lung auscultation is a central part of the physical examination at hospital admission. In this study, the physicians' estimation of airway obstruction by auscultation was determined and compared with the degree of airway obstruction as measured by FEV(1)/FVC values. METHODS: Two hundred and thirty-three patients consecutively admitted to the medical emergency room with chest problems were included. After taking their history, patients were auscultated by an Internal Medicine registrar. The degree of airway obstruction had to be estimated (0=no, 1=mild, 2=moderate and 3=severe obstructed) and then spirometry was performed. Airway obstruction was defined as a ratio of FEV(1)/FVC <70%. The degree of airway obstruction was defined on FEV(1)/FVC as mild (FEV(1)/FVC <70% and >50%), moderate (FEV(1)/FVC <50% >30%) and severe (FEV(1)/FVC <30%). RESULTS: One hundred and thirty-five patients (57.9%) had no sign of airway obstruction (FEV(1)/FVC >70%). Spirometry showed a mild obstruction in 51 patients (21.9%), a moderate obstruction in 27 patients (11.6%) and a severe obstruction in 20 patients (8.6%). There was a weak but significant correlation between FEV(1)/FVC and the auscultation-based estimation of airway obstruction in Internal Medicine Registrars (Spearman's rho=0.328; P<0.001). The sensitivity to detect airway obstruction by lung auscultation was 72.6% and the specificity only 46.3%. Thus, the negative predictive value was 68% and the positive predictive value 51%. In 27 patients (9.7%), airway obstruction was missed by lung auscultation. In these 27 cases, the severity of airway obstruction was mild in 20 patients, moderate in 5 patients and severe in 2 patients. In 82 patients (29.4%) with no sign of airway obstruction (FEV(1)/FVC >70%), airway obstruction was wrongly estimated as mild in 42 patients, as moderate in 34 patients and as severe in 6 patients, respectively. By performing multiple logistic regression, normal lung auscultation was a significant and independent predictor for not having an airway obstruction (OR 2.48 (1.43-4.28); P=0.001). CONCLUSION: Under emergency room conditions, physicians can quite accurately exclude airway obstruction by auscultation. Normal lung auscultation is an independent predictor for not having an airway obstruction. However, airway obstruction is often overestimated by auscultation; thus, spirometry should be performed.     

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.     

The role of FEV6 in the detection of airway obstruction

OBJECTIVES: There are recent reports regarding the use of forced expiratory volume in 6 s (FEV6) in place of forced expiratory vital capacity (FVC) in the detection of airway obstruction. We aimed to investigate the role of FEV6 in comparison with FVC in the evaluation of airway obstruction. METHODS: The pulmonary function tests (PFT) results of all 5114 patients, who had been tested in the pulmonary function laboratory between 1998 and 2003, were retrospectively analyzed to investigate the relationship between FEV6 and FVC. RESULTS: We have found a mean difference of 95.35+/-121.7 (min=0, max=1050) ml (3.37%) when FVC and FEV6 values (FVC-FEV6) of all cases were compared. This difference was found to be higher (180 ml, 7.3%) in patients with airway obstruction. When FEV1/FVC is taken as the gold standard, FEV1/FEV6 had negative predictive value of 92.24% and a sensitivity of 86.09% in the detection of airway obstruction. CONCLUSIONS: Although it is easier to use FEV6 in place of FVC, relatively low sensitivity in that setting may result in the underestimation of airway obstruction. This drawback should be kept in mind when FEV6 is utilized to detect airway obstruction.     

Should forced expiratory volume in six seconds replace forced vital capacity to detect airway obstruction?

It has been suggested that forced expiratory volume in six seconds (FEV(6)) should be substituted for forced vital capacity (FVC) to measure fractions of timed expired volume for airflow obstruction detection. The present authors hypothesised that this recommendation might be questionable because flow after 6 s of forced expiration from more diseased lung units with the longest time constants was most meaningful and should not be ignored. Furthermore, previous studies comparing FEV(6) and FVC included few subjects with mild or no disease. The present study used spirometric data from the USA Third National Health and Nutrition Evaluation Survey with prior published ethnicity- and sex-specific equations for FEV(1)/FEV(6), FEV(1)/FVC and FEV(3)/FVC, and new equations for FEV(3)/FEV(6), all derived from approximately 4,000 adult never-smokers aged 20-80 yrs. At 95% confidence intervals, 21.3% of 3,515 smokers and 41.3% of smokers aged >51 yrs had airway obstruction; when comparing FEV(1)/FEV(6) with FEV(1)/FVC, 13.5% were concurrently abnormal, 1.5% were false positives and 4.1% were false negatives; and when comparing FEV(3)/FEV(6) with FEV(3)/FVC, 11.6% were concurrently abnormal, 3.3% were false positives and 5.7% were false negatives. Substituting forced expiratory volume in six seconds for forced vital capacity to determine the fractional rates of exhaled volumes reduces the sensitivity of spirometry to detect airflow obstruction, especially in older individuals and those with lesser obstruction.     

Lower respiratory illnesses promote FEV(1) decline in current smokers but not ex-smokers with mild chronic obstructive pulmonary disease: results from the lung health study

We analyzed Lung Health Study (LHS) data to assess the effect of self-reported lower respiratory illnesses resulting in physician visits (LRI) on lung function. Participants were 5,887 smokers aged 35-60 yr, FEV(1)/FVC < 0.70 and FEV(1) of 55-90% predicted. Two-thirds were randomized into an intensive smoking cessation program (SI); one-third were advised only to stop smoking (UC). For 5 yr participants had annual spirometry and questioning regarding LRI. SI had greater rates of smoking cessation than usual care (UC) with fewer LRI (p = 0.0008). Sustained quitters had fewer LRI than continuing smokers (p = 0.0003). In the year LRI occurred, FEV(1) did not change in sustained quitters, but decreased significantly in smokers (p = 0.0001) with some recovery the following year if no LRI occurred. Over 5 yr, LRI had a significant effect on rate of decline of FEV(1) only in smokers. In smokers averaging one LRI/yr over 5 yr there were additional declines in FEV(1) of 7 ml /yr (p = 0.001). Smokers with more than one LRI/yr had greater declines. Chronic bronchitis was associated with increased frequencies of LRI, but did not affect their influence on lung function. Smoking and LRI had an interactive effect on FEV(1) in people with mild COPD, and in smokers frequent LRI may influence the long-term course of the disease.