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.     

Six-second spirometry for detection of airway obstruction: a population-based study in Austria

RATIONALE: The presence of airway obstruction is currently defined by Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines on the basis of the post-bronchodilator (BD) FEV(1)/FVC. It has been proposed that the traditional FVC can be replaced with the shorter and less demanding FEV(6) for detecting airway obstruction. OBJECTIVES: A comparison of FEV(1)/FVC and FEV(1)/FEV(6) for the detection of airway obstruction in population-based post-bronchodilator spirometry data. METHODS: A population-based sample of 1,349 adults participated in the Burden of Obstructive Lung Disease study in Austria. Specially trained and certified technicians conducted pre-BD and post-BD spirometry according to American Thoracic Society guidelines and administered standardized questionnaires. A total of 93% of the post-BD test sessions were acceptable, and were included in this analysis. The Third National Health and Nutrition Examination Survey reference equations were used to calculate predicted values and lower limits of normal (LLN) for FEV(1), FEV(6), FVC, FEV(1)/FVC, and FEV(1)/FEV(6). MEASUREMENTS AND MAIN RESULTS: The post-BD FEV(1)/FVC was below the LLN in 199 (15.8%) subjects. The sensitivity of the FEV(1)/FEV(6) for airway obstruction depended greatly on the threshold of percent predicted FEV(1) also used in the definition. The overall sensitivity of FEV(1)/FEV(6) for a diagnosis of airway obstruction, as defined by FEV(1)/FVC (including participants with an FEV(1) above the LLN), was 72.9%, with 98.8% specificity. The sensitivity increased to 98.0% when a low FEV(1) was also required to diagnose post-BD airway obstruction. The discordant cases had long forced expiratory times, often showed a flow-volume curve pattern consistent with two-compartment emptying, and were more often never-smokers. CONCLUSIONS: Six-second spirometry maneuvers (which measure FEV(6)) are as sensitive and specific for post-BD airway obstruction as traditional (prolonged exhalation time) FVC maneuvers only when the definition of airway obstruction includes a low FEV(1).     

Spirometry reference values for Navajo children ages 6–14 years

Spirometry is the most important tool in diagnosing pulmonary disease and is the most frequently performed pulmonary function test. Since respiratory disease is the single greatest cause for morbidity and mortality on the Navajo Nation, the purpose of this study was to create new age and race‐specific pulmonary nomograms for Navajo children. Five hundred fifty‐eight healthy children, ages 6–14 years, attending Navajo Nation elementary schools in Arizona, were asked to perform spirometry to develop population‐specific and tribe‐specific nomograms for forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1), and FEV1 Ratio (FEV1/FVC). Spirometry tests from 284 girls and 274 boys met American Thoracic Society quality control standards. Lung function values, except for FEV1/FVC, all increased with height. The lower limit of the normal range for FEV1/FVC was 80%. The spirometry reference equations from the healthy boys and girls were developed. Height and the natural log of height were significant predictors of FEV1, FVC, and FEF_25–75% in the gender‐specific models. The resulting population‐specific spirometry reference equations should be used when testing Navajo children ages 6–14 years. However, the use of the NHANES III spirometry reference equations for Caucasian children may not result in significant misclassification in clinical settings providing that a maximal effort is given by the Navajo child being tested. Pediatr Pulmonol. 2009; 44:489–496. © 2009 Wiley‐Liss, Inc.     

脉冲振荡法在阻塞性通气功能障碍评定中的价值

目的 探讨脉冲振荡法评定阻塞性通气功能障碍的应用价值及其与常规肺通气功能测定的关系.方法 2007年11月至2008年5月,采用德国耶格公司的肺功能仪及产品说明书给出的预计值公式,测定100例(男72例,女28例)门诊和住院患者的FEV1、FVC、5 Hz时气道阻力(R5)、20 Hz时气道阻力(R20)、结构参数图中的中心阻力(Rc)和周边阻力(Rp)的实测值,FEV1、R5和R20占预计值%,以及FEV1/FVC等指标.并对常规和脉冲振荡法测定肺通气功能的指标进行相关分析.结果 所有受试者均获得满意的脉冲振荡测定结果.当FEV1/FVC低于正常时(＜70%),R5和Rp明显升高至(5.3±2.1)和(6.2±2.9)cm H2O·L-1·S-1(1 cm H2O=0.098 kPa),FEV1与R5、Rp呈显著负相关(r值分别为-0.38和-0.47,均P＜0.01),FVC与R5、Rp也呈显著负相关(r值分别为-0.28和-0.37,均P＜0.01).FEV1占预计值%、FVC占预计值%、FEV1/FVC与R5占预计值%均呈显著负相关(r值分别为-0.49、-0.39和-0.43,均P＜0.01).结论 脉冲振荡法的测定指标可用于评估阻塞性通气功能障碍,尤其是R5的诊断价值最大,并且与常规肺通气功能指标之间有良好的相关性.     

How accurate is spirometry at predicting restrictive pulmonary impairment?

OBJECTIVE: To determine the accuracy with which spirometric measurements of FVC and expiratory flow rates can diagnose the presence of a restrictive impairment. DESIGN: The pulmonary function tests of 1,831 consecutive white adult patients who had undergone both spirometry and lung volume measurements on the same visit over a 2-year period were analyzed. The probability of restrictive pulmonary impairment, defined as a reduced total lung capacity (TLC) below the lower limit of the 95% confidence interval, was determined for each of several categoric classifications of the spirometric data, and additionally for each of several interval levels of the FVC and the FEV1/FVC ratio. SETTING: A large clinical laboratory in a university teaching hospital using quality-assured and standardized spirometry and lung volume measurement techniques according to American Thoracic Society standards. RESULTS: Two hundred twenty-five of 1,831 patients (12.3%) had a restrictive defect. The positive predictive value of spirometry for predicting restriction was relatively low; of 470 patients with a low FVC on spirometry, only 41% had restriction confirmed on lung volume measurements. When the analysis was confined to the 264 patients with a restrictive pattern on spirometry (ie, low FVC and normal or above normal FEV1/FVC ratio), the positive predictive value was 58%. Conversely, spirometry had a very favorable negative predictive value; only 2.4% of patients (32 of 1,361) with a normal vital capacity (VC) on spirometry had a restrictive defect by TLC measurement. The probability of a restrictive defect was directly and linearly related to the degree of reduction of FVC when the FVC was < 80% of predicted (p = 6.002). Combining the FVC and the FEV1/FVC ratio improved the predictive ability of spirometry; for all values of FVC < 80% of the predicted amount, the likelihood of restrictive disease increased as the FEV1/FVC ratio increased. CONCLUSIONS: Spirometry is very useful at excluding a restrictive defect. When the VC is within the normal range, the probability of a restrictive defect is < 3%, and unless restrictive lung disease is suspected a priori, measurement of lung volumes can be avoided. However, spirometry is not able to accurately predict lung restriction; < 60% of patients with a classical spirometric restrictive pattern had pulmonary restriction confirmed on lung volume measurements. For these patients, measurement of the TLC is needed to confirm a true restrictive defect.     

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.     

Spirometry in an unselected group of 6-year-old children: the DARC birth cohort study

This study presents reference equations for spirometric parameters in 6-year-old children and evaluates the ability of spirometry to discriminate healthy children from children with asthma. Baseline spirometry and respiratory symptoms were assessed in 404 children participating in a longitudinal birth cohort study. Children with known asthma, possible asthma and a control group also performed bronchodilator measurements. At least two acceptable flow-volume curves at baseline were obtained by 368/404 children (91%). The two best values for FEV1 and FVC were within 5% of each other in 88% and 83% of children, respectively. Linear regression analyses for 242 children included in the reference population demonstrated height to be the main predictor of all spirometric indices except FEV1/FVC. FEV1, FEV75, and FVC correlated reasonably to anthropometric data in contrast to flow parameters. Gender differences were found for FEV1, FVC, and FEV75, but not for flow parameters. Asthma was diagnosed in 25/404 children. Baseline lung function in healthy children and children with asthma overlapped, although asthmatic children could be discriminated to some extent. Bronchodilator tests showed a difference in Delta FEV1(mean) between healthy children and children with asthma (3.1% vs. 6.1%, P < 0.05). At a cut-off point of Delta FEV1 = 7.8%, bronchodilator tests had a sensitivity of 46% and a specificity of 92% for current asthma. Spirometry including bronchodilator measurements was demonstrated to be feasible in 6-year-old children and reference values were determined. Spirometry aids the diagnosis of asthma in young children, but knowledge on sensitivity and specificity of these measurements is a prerequisite.     

FEV1/FVC ratio of 70% misclassifies patients with obstruction at the extremes of age

BACKGROUND: The American Thoracic Society recommends using the lower limit of normal (LLN) method to diagnose obstructive lung disease. However, few studies have investigated the clinical relevance of these recommendations. We compared the LLN derived from available data sets to a fixed ratio (FEV1/FVC, < 75% or 70%) and also to the FEV1/FVC percent predicted ratio to determine the impact of changing the FEV1/FVC "cutoff" on the spirometric diagnosis of obstructive lung disease. METHODS: FEV1, FVC, FEV1/FVC ratio, age, race, sex, height, and weight were recorded from 1,503 pulmonary function tests. Predicted values were calculated using the Third National Health and Nutrition Examination Study data set (Hankinson), and reference values from studies by Crapo, Knudson, and Morris. In addition, the LLN of the FEV1/FVC ratio was calculated for the Hankinson and Crapo reference values. RESULTS: The number of studies interpreted as obstructed varied from 37% using the Hankinson data set to 55% using the 75% fixed ratio method. Comparing the LLN method vs the 70% fixed ratio method resulted in 7.5% (Hankinson LLN vs 70% fixed) and 6.9% (Crapo LLN vs 70% fixed), which were discordant results. Age was the strongest predictor of discordance, and 16% of subjects > 74 years of age had discordant results comparing Hankinson values to the 70% fixed method. CONCLUSION: At the extremes of age and height, a large number of spirometry test results will be interpreted as showing an obstructive defect if a 70% fixed ratio method is used for interpretation compared with the LLN derived from the Hankinson data set.     

Prevalence of Airflow Obstruction in Nonsmoking Older Individuals Using Different Spirometric Criteria: The AGES Reykjavik Study

Abstract

Background: The prevalence and characteristics of airway obstruction in older individuals varies widely with the definition used. We used a random sample of never smoking older population in Iceland to compare the prevalence and clinical profile of subjects diagnosed with Chronic Obstructive Pulmonary Disease (COPD) based on different spirometric criteria. Material and methods: The study uses data from the Age, Gene/Environment Susceptibility–Reykjavik Study, comprising survivors from the Reykjavik Study. Procedures included standardized questionnaires and pre-bronchodilator spirometry for measurement of forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). Results: Total of 495 individuals (150 men and 345 women) met study criteria. Mean age 77 years (range 66-92 years) using fixed ratio (FEV1/FVC < 70%) up to 29% of the population were diagnosed with COPD Stage I. The prevalence of COPD increased with age. Only 7 among 495 (1.4%) were diagnosed with COPD using FEV1/FVC LLN and FEV1 LLN. Conclusion: Application of the GOLD criteria for diagnosis of COPD in older lifelong never smoking subjects identifies a substantial number of non-symptomatic subjects as having COPD. If airway obstruction is defined by FEV1/FVC and FEV1 being below the LLN using appropriate reference equations, only very few non-smoking older individuals fulfill the criteria for COPD.     

The FEV1/FEV6 predicts lung function decline in adult smokers

The use of FEV1/FEV6 in place of the traditional FEV1/FVC to detect airways obstruction during spirometry testing performed by primary care providers would reduce time and patient effort. We hypothesized that the FEV1/FEV6, would predict the subsequent decline in FEV1 in adult cigarette smokers who enrolled in the multicenter Lung Health Study. Ten clinical centers in the U.S. and Canada recruited 5887 male and female smokers, aged 35-60 years, with borderline to mild airways obstruction by spirometry. Those who successfully stopped smoking during the 5-yr study (usually as the result of the smoking cessation intervention) were excluded from this analysis. In those continuing to smoke, the relative strength of spirometric predictors of the change in FEV1 during 5 years of follow-up (DFEV1) was determined using a linear regression model. The following covariates were significant independent predictors of DFEV1: the baseline degree of airways obstruction, age, gender, cigarettes per day, years of education, and bronchial hyperresponsiveness. The FEV1/FEV6 was nearly as strong an independent predictor as was the FEV1/FVC (a traditional index of airways obstruction). The degree of airways obstruction, as determined by the FEV1/FEV6 from spirometry, is an independent predictor of subsequent decline in lung function; and therefore, may be used to detect smokers at higher risk of developing COPD.     

Obstructive and restrictive spirometric patterns: fixed cut-offs for FEV1/FEV6 and FEV6.

The purpose of this study was to determine fixed cut-off points for forced expiratory volume in one second (FEV(1))/FEV(6) and FEV(6) as an alternative for FEV(1)/forced vital capacity (FVC) and FVC in the detection of obstructive and restrictive spirometric patterns, respectively. For the study, a total of 11,676 spirometric examinations, which took place on Caucasian subjects aged between 20-80 yrs, were analysed. Receiver-operator characteristic curves were used to determine the FEV(1)/FEV(6) ratio and FEV(6) value that corresponded to the optimal combination of sensitivity and specificity, compared with the commonly used fixed cut-off term for FEV(1)/FVC and FVC. The data from the current study indicate that FEV(1)/ FEV(6) <73% and FEV(6) <82% predicted can be used as a valid alternative for the FEV(1)/FVC <70% and FVC <80% pred cut-off points for the detection of obstruction and restriction, respectively. The statistical analysis demonstrated very good, overall, agreement between the two categorisation schemes. For the spirometric diagnosis of airway obstruction (prevalence of 45.9%), FEV(1)/FEV(6) sensitivity and specificity were 94.4 and 93.3%, respectively; the positive and negative predictive values were 92.2 and 95.2%, respectively. For the spirometric detection of a restrictive pattern (prevalence of 14.9%), FEV(6) sensitivity and specificity were 95.9 and 98.6%, respectively; the positive and negative predictive values were 92.2 and 99.3%, respectively. This study demonstrates that forced expiratory volume in one second/forced expiratory volume in six seconds <73% and forced expiratory volume in six seconds <82% predicted, can be used as valid alternatives to forced expiratory volume in one second/forced vital capacity <70% and forced vital capacity <80% predicted, as fixed cut-off terms for the detection of an obstructive or restrictive spirometric pattern in adults.     

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.     

Validity of the American Thoracic Society and other spirometric algorithms using FVC and forced expiratory volume at 6 s for predicting a reduced total lung capacity

OBJECTIVES: (1) To compare the performance of three spirometric algorithms developed to predict whether the total lung capacity (TLC) is reduced vs normal or increased, (2) to determine if forced expiratory volume at 6 s (FEV(6)) can be substituted for FVC in these algorithms, and (3) to determine if ascertainment bias was present in patients referred for the measurement of spirometry and TLC compared to patients referred for spirometry only. METHODS: We analyzed the results of 219 consenting consecutive patients referred to a New Zealand tertiary hospital respiratory laboratory for spirometry and TLC measurements. Spirometry results from 370 patients referred for spirometry but not lung volumes were used to test for potential ascertainment bias. Spirometry results were analyzed using the lower limit of normal (LLN) values from the third National Health and Nutrition Examination Study reference equations. The equations of Goldman and Becklake, and Crapo were used to classify TLC as normal or abnormal. Receiver operator characteristic curves were used to produce an algorithm using the LLN for FVC and FEV(6). The performances of previous algorithms and our own algorithms were analyzed for predicting a reduced lung volume against the "gold standard," plethysmographic TLC. RESULTS: All three algorithms predicted a reduced TLC with an accuracy of approximately 50%. In contrast, all algorithms predicted TLC was either normal or increased with an accuracy of > or = 99% regardless of the reference set used. The algorithms based on FEV(6) performed equally as well as the FVC algorithms. No ascertainment bias was found. CONCLUSIONS: This study provides evidence that spirometry-based algorithms can accurately predict when TLC is either normal or increased, and can also increase the a priori probability that TLC is reduced to approximately 50%. FEV(6) is equivalent to FVC in these predictions.     

Spirometric values in Gypsy (Roma) children

Values of spirometry indices vary among subjects of similar age, gender and somatometrics but of different ethnic origins. Low socioeconomic status in childhood is inversely related to lung growth. The aim of this investigation was to assess spirometry values in Gypsy children and compare them to reported values for Caucasians. Gypsy students attending primary schools in Central Greece were recruited. Spirometry indices were measured using a portable spirometer. Regression analysis was applied to construct prediction equations for forced vital capacity (FVC) and other spirometric indices (FEV(1), FEF(50), FEF(25), FEF(25-75)) based on standing height. Predicted spirometric values were compared to values for Caucasians from published studies. In 152 children (ages 5-14 years; 57 girls) lung function increased linearly with height: spirometry index=intercept+[slopexheight], (r(2)=0.68 for FVC and FEV(1) in girls; r(2)=0.78 for FVC and r(2)=0.74 for FEV(1) in boys). Excluding boys-but not girls-in puberty increased fit for FVC (r(2)=0.83) and FEV(1) (r(2)=0.79). Mean predicted values were 5-10% lower than values for Caucasians. In Gypsy children, FVC and expiratory flow function increase linearly with standing height and predicted values are lower than those for Caucasians of similar height.     

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.     

MedikroSpiroStarplrotar临床应用研究USB便携式肺功能仪

目的比较在不同肺功能状态人群中用Medikro@SpiroStarUSB便携式肺功能仪与传统JaegerMasterScreenIOS肺功能仪测定的一致性。方法用JaegerMasterScreenIOS肺功能仪与MedikroSpiroStarUSB肺功能仪分别对100例正常肺功能者,阻塞性、限制性和混合性通气功能障碍的患者进行肺功能测定,并用组内相关系数（ICC）和Bland—Altman方法对其中的几个关键参数[肺活量（VC）、用力肺活量（FVC）、第1秒用力呼气量（FEV1）、FEV。占预计值％（FEV1％pred）、FEV1／FVC]进行分析比较。结果与Jaeger肺功能仪相比,SpiroStar肺功能仪对肺功能关键参数的测量值没有显著偏倚。ICC值分别为0．968、0．970、0．977、0．967、0．938。受试者前后两次测量的各参数的差值绝大部分（94％以上）落在95％的一致性区间内。结论与传统Jaeger肺功能仪相比,SpiroStar肺功能仪对VC、FVC、FEV1、FEV,％pred、FEV1／FVC等肺功能关键参数的测量无显著偏倚,故当无条件在肺功能室进行标准的肺功能试验时,便携式SpiroStar肺功能仪是一个较为理想的替代选择。     

Reproducibility of spirometry in Mexican workers and international reference values

OBJECTIVE: To describe spirometric function and adjustment to foreign prediction equations in Mexican workers claiming work related disability. MATERIAL AND METHODS: We reviewed 5771 spirometries done at the Mexican National Institute of Respiratory Diseases performed with equipment and methods proposed by the American Thoracic Society. With the spirometries we generated multiple regression equations separated for men and women based on age and height, compared to other in common use reported by Knudson and Hankinson in North America and by Quanjer in europeans. RESULTS: 80% of the tests were reproducible for FVC and FEV1 according to ATS, whereas 10% were reproducible for neither. Mean FVC in men was 12% above values reported by Quanjer, 22% above Knudson, 3% above Hankinson and 6% above Rodriguez-Reynaga, whereas similar values for women were 18%, 10%, 0% and 1%. Excluding obese and those who had less than 2 acceptable maneuvers, the numbers increase by 1-2%. FEV1 was also above predicted. CONCLUSIONS: Most workers requesting disability are able to generate a reproducible spirometry. However for the same gender, age and height, workers had a FEV1 and a FVC above normal values reported by Knudson and Quanjer and are more similar to those reported by Hankinson in Mexican-Americans. While a set of appropriate reference values are obtained, regression equations obtained from the studied group will generate less error in the evaluation of disability in mexican workers. The English version of this paper is available at: http://www.insp.mx/salud/index.html.     

Spirometry in early childhood in cystic fibrosis patients

BACKGROUND: Spirometry data in cystic fibrosis (CF) patients in early childhood is scarce, and the ability of spirometry to detect airways obstruction is debatable. OBJECTIVE: To evaluate the ability of spirometry to detect airflow obstruction in CF patients in early childhood. METHODS: CF children (age range, 2.5 to 6.9 years) in stable clinical condition were recruited from five CF centers. The children performed guided spirometry (SpiroGame; patented by Dr. Vilzone, 2003). Spirometry indices were compared to values of a healthy early childhood population, and were analyzed with relation to age, gender, and clinical parameters (genotype, pancreatic status, and presence of Pseudomonas in sputum or oropharyngeal cultures). RESULTS: Seventy-six of 93 children tested performed acceptable spirometry. FVC, FEV1, forced expiratory flow in 0.5 s (FEV0.5), and forced expiratory flow at 50% of vital capacity (FEF50) were significantly lower than healthy (z scores, mean +/- SD: - 0.36 +/- 0.58, - 0.36 +/- 0.72, - 1.20 +/- 0.87; and - 1.80 +/- 1.47, respectively; p < 0.01); z scores for FEV1 and FVC were similar over the age ranges studied. However, z scores for FEV0.5 and forced expiratory flow at 25 to 75% of vital capacity were significantly lower in older children compared to younger children (p < 0.001), and a higher proportion of 6-year-old than 3-year-old children had z scores that were > 2 SDs below the mean (65% vs 5%, p < 0.03). Girls demonstrated lower FEF50 than boys (z scores: - 2.42 +/- 1.91 vs - 1.56 +/- 1.23; p < 0.001). Clinical parameters evaluated were not found to influence spirometric indices. CONCLUSIONS: Spirometry elicited by CF patients in early childhood can serve as an important noninvasive tool for monitoring pulmonary status. FEV0.5 and flow-related volumes might be more sensitive than the traditional FEV1 in detecting and portraying changes in lung function during early childhood.     

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.     

Prevalence of Airflow Obstruction as Measured by Spirometry,in Rural Southern Indian Adults

Abstract

Rural population-based estimates of airflow obstruction based on spirometry are unavailable from southern India. This study assessed the prevalence of spirometry-defined airflow obstruction in Vellore, Tamil Nadu.

A cross sectional survey was done in nine villages, among adults aged ≥30?years, where previous cardiovascular surveys had been conducted (1994, 2011). Population proportional to size sampling was used to select 20 clusters, with sampling from all streets proportional to the number of households. One person randomly selected per household was interviewed for symptoms and risk factors. A respiratory therapist performed pre and post bronchodilator spirometry on all, following American Thoracic Society criteria. Airflow obstruction was defined as pre-bronchodilator Forced Expiratory Volume 1?s/Forced Vital Capacity (FEV1/FVC)?<?Lower Limit of Normal (LLN, derived from local prediction equations) and compared to other criteria.

Of 1015 participants, 787 completed technically acceptable spirometry. The prevalence of airflow obstruction was 9.0% (95% CI: 5.8%–9.6%, 71). Fixed obstruction (post bronchodilator FEV1/FVC?<?LLN) was 4.6% (95% CI: 3.1%–6.1%, 36), and 4.1% (95% CI: 2.7%–5.5%, 32) using post bronchodilator FEV1/FVC?<?70%. The GOLD criteria missed 56% (40) of those with airflow obstruction, of which 87.5% were females. Although 63.4% with airflow obstruction had moderate to severe disease, 82.2% were not on treatment and only 48.9% reported symptoms in the previous year.

This study estimates prevalence of airflow obstruction based on spirometry in rural southern India. Despite significant impairment on spirometry, majority were undiagnosed, and half did not report symptoms.