Spirometric pulmonary function parameters of healthy Chinese children aged 3–6 years in Taiwan

Spirometry is a well‐known technique for evaluating pulmonary function, but few studies have focused on preschool children. The aim of this study was to determine reference values of forced spirometric parameters in young Chinese children, aged 3–6 years, in Taiwan. Spirometric measurements were performed at day care centers by experienced pediatricians. Of 248 children without a history of chronic respiratory illness, at least two valid spirometric attempts were obtained from 214 children (109 boys and 105 girls; age: 36–83 [mean = 61] months; height: 90–131 [mean = 111] cm). Values of forced expiratory volume in 1 sec (FEV₁) and 0.5 sec (FEV_0.5), forced vital capacity (FVC), peak expiratory flow rate (PEF), forced expiratory between 25% and 75% FVC (FEF_25–75), and forced expiratory flow rate at 25%, 50%, and 75% of FVC (FEF₂₅, FEF₅₀, and FEF₇₅) were derived and analyzed. There were significant positive correlations between study parameters and body height, body weight, and age. Height was the most consistently correlated measurement in both boys and girls. Although boys tended to have higher spirometric values than girls, we found significant differences only in FVC and FEV₁ between boys and girls aged 6 years. The regression equations of each parameter were obtained. In conclusion, spirometric pulmonary function tests are feasible in 3‐ to 6‐year‐old children. The obtained values and regression equations provide a reference for Chinese preschool children and may be of value in evaluating pulmonary function of children with respiratory problems in this age group. Pediatr Pulmonol. 2009; 44:676–682. © 2009 Wiley‐Liss, Inc.     

Effect of passive smoking,asthma, and respiratory infection on lung function in Australian children

We have calculated normal standards for lung function of Australian children and have estimated the effects on lung function of passive smoking, current asthma, past asthma, and a current respiratory infection. Three cross-sectional samples of children in school years 3–5 (aged 8–11 years) were studied. The 2765 children were from two rural regions of NSW and from the city of Sydney. Details of passive smoking and respiratory illness were collected by a questionnaire sent to parents. Forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV₁), peak expiratory flow rate (PEFR), and forced mid-expiratory flow rate (FEF_25–75%) were used as measures of lung function. Airway responsiveness was assessed by histamine inhalation test. Data from 1278 “normal” children were used in regression analysis to calculate prediction models for lung function. Passive smoking was associated with reduced FEV₁, PEFR, and FEF_25–75%. Children with current asthma had reduced FEV₁ and FEF_25–75% and children with past asthma had reduced FEF_25–75%. Children with a current respiratory infection had reduced FVC₁, FEV₁, PEFR, and FEF_25–75% The effects of these deficits on the future lung function of these children is not known but is likely to be important. Pediatr Pulmonol. 1994;18:323–329 © Wiley-Liss, Inc.     

Pulmonary function between 6 and 18 years of age

Pulmonary function of children aged 6–18 years is described based on 82,462 annual measurements of forced vital capacity (FVC), forced expired volume in 1 second (FEV₁), and forced expiratory flow between 25% and 75%of FVC (FEF_25–75%) from 11,630 white children and 989 black children. Median height, FVC, FEV₁ FEV₁/FVC₁ and FEF_25–75% for each 3 months of age are compared among race and sex subgroups. Race— and sex-specific percentile distributions of FVC, FEV₁, FEV₁/FVC, and FEF_25—75% are presented for each centimeter of height (growth curves). For the same height, boys have greater lung function values than girls, and whites have greater ones than blacks. Lung function increases linearly with age until the adolescent growth spurt at about age 10 years in girls and 12 in boys. The pulmonary function vs. height relationship shifts with age during adolescence. Thus, a single equation or the pulmonary function-height growth chart alone does not completely describe growth during the complex adolescent period. Nevertheless, race- and sex-specific growth curves of pulmonary function vs. height make it easy to display and evaluate repeated measures of pulmonary function for an individual child. Race-, sex-, and age-specific regression equations based on height are provided, which permit the evaluation of growth during adolescence with improved accuracy and, more importantly, in comparison with previous observations for the same child. © 1993 Wiley-Liss, Inc.     

Reference Values and Prediction Equations for FVC and FEV1 in the Greek Elderly

Spirometry prediction equations obtained from middle-age adults, when extrapolated for the elderly, may lead to inaccurate interpretations. The purpose of this study was to determine prediction equations for forced vital capacity (FVC) and forced expiratory volume (FEV₁) in the Greek elderly population. Spirometry prediction equations for normal FVC and FEV₁ have been derived from tests on 71 healthy persons (38 men, 33 women) aged older than 60 years (range, 65–85 years), nonsmokers, white race, urban population using techniques and equipment that meet American Thoracic Society recommendations. Regression analysis using age, height, and weight as independent variables was used to provide prediction equations and values for both sexes. The FVC age coefficient in this healthy group was about 47.19 mL/y for elderly men and 34.27 mL/y for elderly women, and the FEV₁ age coefficient was about 52.8 mL/y for elderly men and 46.4 mL/y for elderly women . Values from this study predicted equations were compared with those from some of the most commonly used sources of spirometry predicted equations. The FVC and FEV₁ predicted values were found to be of less mean square error than that of other compared studies. Higher correlation is between FVC and FEV₁ predicted values by the present model and FVC and FEV₁ observed values in both sexes. The higher correlation between FVC and FEV₁ predicted and observed from this study allows the use of our model for predicting in a rather reliable way the FVC and FEV₁ for elderly Greek individuals. Accepted for publication: 25 April 2000     

Effects of Instructions on Pulmonary Function Values

This study examined the influence of specific components of standard forced expiratory maneuver instructions on spirometric values. Thirty-six subjects received instructions and practice in performing the forced expiratory maneuver prior to experimental manipulation of instructions. Instructions to begin with a maximal inhalation and then to blow into the spirometer as hard, fast, and long as possible were reiterated prior to every maneuver. During the instruction manipulation period, subjects were additionally instructed to blow either harder, faster, or longer. Overall, instructions to blow harder resulted in the most stable pattern of increase in all measures (IC, FVC, FEV₁, FEF_25–75%, and FEV₁/FVC); instructions to blow longer consistently led to decreases in some values.     

Clinical Significance of Pulmonary Function Tests in Patients with Acute Pancreatitis

The aim of the present study was to investigate changes in pulmonary function tests (PFTs) in patients with acute pancreatitis (AP), to compare them with those changes in healthy controls, and to analyze the relationship between these parameters and computed tomography severity index (CTSI) and Ranson's criteria scores as markers of disease severity. This study included 40 patients with AP without a diagnosis of any pulmonary disease and 40 sex- and age-matched healthy controls. All participants were evaluated with simple PFTs and single-breath carbon monoxide (CO) diffusion tests. Patients with AP were also evaluated according to their CTSI and Ranson's criteria scores as markers of disease severity. The forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), FEV₁/FVC, and peak expiratory flow, which determine lung capacity, were similar in the two groups. The forced expiratory volume during the middle half of the FVC (FEF_{25 – 75%}), CO diffusing capacity (D_LCO), and ratio of D_LCO to alveolar ventilation (D_LCO/V_A), which determines alveolar membrane permeability, revealed a statistically significant decline in pulmonary gas exchange in patients with AP (P < 0.05). Correlation analysis showed that there is a significant negative relationship between CTSI and Ranson's criteria scores with FEF_{25 – 75%}, D_LCO, and D_LCO/V_A (P < 0.05). We suggest that AP may cause impaired alveolar gas exchange without manifest pulmonary diseases. The effect of AP on FEF_{25 – 75%}, D_LCO, and D_LCO/V_A appears to be dependent not only on the disease, but also on its severity. FEF_{25 – 75%}, D_LCO, and D_LCO/V_A may give additional prognostic information in patients with AP in the initial evaluation.     

Genetic Influences on Pulmonary Function: A Large Sample Twin Study

Heritability of forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), and peak expiratory flow (PEF) has not been previously addressed in large twin studies. We evaluated the genetic contribution to individual differences observed in FEV₁, FVC, and PEF using data from the largest population-based twin study on spirometry. Specially trained lay interviewers with previous experience in spirometric measurements tested 4,314 Danish twins (individuals), 46–68 years of age, in their homes using a hand-held spirometer, and their flow-volume curves were evaluated. Modern variance component sex-limitation models were applied to evaluate possible genetic differences between the sexes for FEV₁, FVC, and PEF. Estimates were adjusted for age, height, and smoking. For FEV₁, additive genetic effects of 61% (95% CI 56–65) were observed. For FVC, the additive genetic contribution was 26% (3–49%) and the dominant genetic contribution was 29% (4–54%). For PEF, our models showed an additive genetic contribution of 43% (31–52%) for men, but genetic influences were not significant in women. We found no significant differences between dizygotic same-sex twins and dizygotic opposite-sex twins for FEV₁, FVC, and PEF, suggesting absence of qualitative genetic differences between the sexes. Sex-difference heritability for PEF suggested possible quantitative genetic differences between the sexes for this index. Genetic effects contributed significantly to individual differences observed in FEV₁, FVC, and PEF. Qualitative sex differences were absent for all spirometric measures, while quantitative sex differences were observed only for PEF, with heritability being substantial in men but negligible in women.     

Association Between Smoking and Respiratory Function Before and After Menopause

There is a lack of evidence about whether menopausal status influences the effect of smoking on lung function. This study examined the association between smoking and menopausal status and lung function independent of each other. Data were from a cohort of women attending the 21-year follow-up of the Mater University of Queensland Study of Pregnancy. The study was based on 2020 women who provided data on respiratory function, smoking, and menopausal status. A Spirobank G spirometer system was used to measure forced vital capacity (FVC), forced expiratory volume in first second (FEV₁), and forced expiratory flow between 25 and 75% of forced vital capacity (FEF_25–75). Smoking and menopausal status were assessed by self-report. Respiratory function was associated with cigarette smoking, menopausal status, and hormone replacement therapy. Regardless of smoking status, postmenopausal women had poorer lung function when compared with premenopausal women. In multivariate analysis, cigarette smoking was associated with lower FVC, FEV₁, and FEF_25–75, with the magnitude of effect being stronger for women who were postmenopausal. The data suggest that the impact of smoking intensifies after menopause. It seems plausible that effective quit-smoking programs, particularly after menopause, may lead to better lung function and reduced morbidity and mortality in women.     

Mild Asthmatics Benefit from Music Therapy

Objective. The aim of the study was to evaluate the effectiveness of pulmonary rehabilitation with music therapy in patients with asthma. Methods. Seventy-six selected inpatients (54 women and 22 men; mean age = 56.4 years; SD = 11.8) with stable asthma underwent pulmonary rehabilitation in two groups: standard versus music therapy. Results. After the intervention, an increase in analyzed spirometric values (forced expiratory volume at the first second (FEV₁), FEV₁ as a percentage of vital capacity (FEV₁ % FVC), forced expiratory flow at 25%, 50%, and 75% of vital capacity (FEF₂₅, FEF₅₀, and FEF₇₅, respectively), and peak expiratory flow) was observed in both the groups (p < .05) but without any intergroup differences (p > .05). A greater increase of mean FEV₁ % FVC, FEF₅₀, and FEF₇₅ values was observed only in the patients with mild asthma from the music therapy group (p < .05). In both the groups, a dyspnea reduction was noted (p < .001). However, it was influenced neither by the type of rehabilitation nor by the gender (p > .05), but the interaction of these variables was significant (p = .044). A dyspnea reduction was observed in women in both the groups (p < .001) and in men in the music therapy group only (p = .001). A change in the value of anxiety (6.43, SD = 7.73) on the 10th day compared with the first day of the study was noticed (p < .001). However, this change was not influenced by the type of rehabilitation, gender, or a combination of these two variables (p > .05). Conclusion. Music therapy improves the respiratory function in patients with mild asthma and reduces dyspnea mainly in men with asthma.     

Canadian prediction equations of spirometric lung function for Caucasian adults 20 to 90 years of age: results from the Canadian Obstructive Lung Disease (COLD) study and the Lung Health Canadian Environment (LHCE) study

BACKGROUND:

Currently, no reference or normative values for spirometry based on a randomly selected Canadian population exist.

OBJECTIVE:

The aim of the present analysis was to construct spirometric reference values for Canadian adults 20 to 90 years of age by combining data collected from healthy lifelong nonsmokers in two population-based studies.

METHOD:

Both studies similarly used random population sampling, conducted using validated epidemiological protocols in the Canadian Obstructive Lung Disease study, and the Lung Health Canadian Environment study. Spirometric lung function data were available from 3042 subjects in the COLD study, which was completed in 2009, and from 2571 subjects in the LHCE study completed in 1995. A total of 844 subjects 40 to 90 years of age, and 812 subjects 20 to 44 years of age, were identified as healthy, asymptomatic, lifelong nonsmokers, and provided normative reference values for spirometry. Multiple regression models were constructed separately for Caucasian men and women for the following spirometric parameters: forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC ratio, with covariates of height, sex and age. Comparison with published regression equations showed that the best agreement was obtained from data derived from random populations.

RESULTS:

The best-fitting regression models for healthy, never-smoking, asymptomatic European-Canadian men and women 20 to 90 years of age were constructed. When age- and height-corrected FEV₁, FVC and FEV₁/FVC ratio were compared with other spirometry reference studies, mean values were similar, with the closest being derived from population-based studies.

CONCLUSION:

These spirometry reference equations, derived from randomly selected population-based cohorts with stringently monitored lung function measurements, provide data currently lacking in Canada.     

Spirometry values in a Greek population: Is there an appropriate reference equation?

Background and objective: Most published reference values for lung function test (LFT) parameters introduce systematic bias. The aim of this study was to compare measured values of FEV₁ and FVC with the corresponding normal predicted values in a Greek population, and to produce reference equations for LFT parameters in this population. Methods: In a cross‐sectional study conducted in Macedonia, Greece, 1080 adult healthy, non‐smokers (432 men, 648 women, aged 18–80 years), underwent spirometry. Measured values of FVC and FEV₁ were compared with predicted values determined using three existing sets of reference equations: one recently derived from a European population and two others widely used in Europe (European Coal and Steel Community; ECSC) and the USA (National Health and Nutrition Examination Survey; NHANES III). Height and age were entered into the multivariate regression analysis to produce reference equations for LFT parameters. Results: All three published sets of equations underpredicted FEV₁ in men. FVC was accurately predicted by all equations except NHANES III. The discrepancy was even greater among women; the ECSC equation underpredicted both FEV₁ and FVC, the NHANES III equation overpredicted both FEV₁ and FVC, while the third set of equations accurately predicted FEV₁ but overpredicted FVC. The derived reference equation for FEV₁ in men was ?0.28 × age + 0.057 × height ? 4.91, and in women ?0.021 × age + 0.039 × height ? 2.58. The derived reference equation for FVC in men was ?0.28 × age + 0.071 × height ? 6.763, and in women ?0.019 × age + 0.056 × height ? 5.018. Conclusions: Measured FEV₁ and FVC values in a Greek population differed significantly from those predicted using previously published reference equations. The new locally derived spirometry reference equations may be more suitable for evaluation of lung function in everyday practice.     

Sensitivity of different spirometric tests for detecting airway obstruction in childhood asthma

Objective: The objective of this study was to compare different measures of airflow obstruction by spirometry in childhood asthma. The objectives were; (a) to compare sensitivity of large airway tests (FEV₁ and PEFR) with tests at low lung volumes (small airways) (FEF_25–75, FEF₅₀ and FEF₇₅); (b) compare within each group which individual tests are more sensitive. Methods: This was a retrospective analysis of 2307 spirometry tests performed during outpatient visits on 821 doctor-diagnosed asthma patients aged 6–18. Tests were deemed acceptable if they were acceptable and repeatable by American Thoracic Society (ATS) criteria. Results: In mild obstruction, FEV₁ detected 6.8% abnormal tests while FEF₇₅ detected 33% (p?<?0.0001). In more severe obstruction, the difference was more obvious (FEV₁ 14.8%; FEF₇₅ 71%). Tests at low lung volumes (small airway tests) were also more sensitive than PEFR. Within groups, FEV₁ was more sensitive than PEFR in the large airway tests and FEF₇₅ was more sensitive than FEF_25–75 and FEF₅₀ among the tests at low lung volumes (small airway tests). The FEV₁/FVC ratio correlated more closely with tests at low lung volumes (small airway tests), than with large airway tests. Conclusions: (1) Tests at low lung volumes (small airway tests) are more sensitive than large airway tests; (2) Within groups, the FEV₁ is better than PEFR and FEF₇₅ is better than FEF_25–75 or FEF₅₀.     

Association of Psychiatric Disorders,Asthma and Lung Function in Early Adulthood

Objective. To examine the association between psychiatric disorders, asthma, and lung function in young adults. Study Design. Data were from the Mater–University of Queensland Study of Pregnancy (MUSP). The study was based on 2443 young adults (1193 male and 1250 female) for whom data were available on psychiatric disorders, asthma, and respiratory function. Life time and last 12 months’ generalized anxiety, panic, posttraumatic stress disorder (PTSD), and depressive disorders were assessed using a computerised version of the Composite International Diagnostic Interview (CIDI-Auto). A Spirobank G spirometer system was used to measure forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and forced expiratory flow between 25% and 75% of forced vital capacity (FEF_25–75%). Results. Participants with mental health disorders were more likely to have experienced asthma before or to use asthma medication at 21 years. However, for both males and females, life time and last 12 months’ experience of generalized anxiety, panic, PTSD, and depressive disorders were not statistically significantly associated with FVC, FEV₁, and FEF_25–75%, except a modest association with major depressive disorders for males. Conclusion. There is an association between mental health and asthma, but the relationship between mental health and lung function appeared to be confounded by the respondent's gender. More narrowly based prospective studies are required to determine the causal pathway between mental disorders and asthma.     

Pulmonary Function and Airway Hyperresponsiveness in Adults with Sickle Cell Disease

Study Objectives Pulmonary involvement is a major cause of morbidity and mortality in patients with sickle cell disease (SCD). Although a high prevalence of airway hyperresponsiveness (AHR) has been reported, there are no studies demonstrating the relationship between AHR and acute chest syndrome (ACS) in adults with SCD. We investigated AHR prevalence, lung function abnormalities, and the relationships of these variables with ACS in SCD patients. Method Thirty-one adult patients without asthmatic symptoms were compared with 31 matched controls. Expiratory flow rates, lung volumes, carbon monoxide diffusion capacity (DLCO), and methacholine provocation test (MPT) results were assessed. Results Forced vital capacity (FVC), forced expiratory volume in one second, forced expiratory flow rate at 25% to 75% of FVC (FEF_25%–75%), peak expiratory flow rate, total lung capacity, and DLCO values were significantly lower in the patient group than in the controls. No significant difference in pulmonary function test results was found between patients with and without a history of ACS. Fifteen patients with SCD (48%) and only 5 controls (16%) had AHR (p = 0.007). A significant correlation was found between the number of ACS episodes and MPT positivity (r = 0.379, p = 0.035). The FEF_25%–75% values were significantly lower in patients with positive MPT results than in patients with negative MPT results (p = 0.027). Conclusion The prevalence of AHR was high in adult patients with SCD. A significant correlation was found between AHR and recurrent ACS episodes. Anti-inflammatory controller agents can be used routinely to decrease pulmonary morbidity associated with SCD, even in the absence of asthmatic symptoms.     

Spirometric patterns in childhood asthma: Peak flow compared with other indices

The objective of this study was to determine patterns of pulmonary function abnormalities and to evaluate how adequately peak flow monitoring was correlated to other spirometric indices in childhood asthma. Ninety-one children, aged 8-15 years, with moderate-to-severe asthma were repeatedly tested in a summer camp. On-site medical staff permitted 24-hour-a-day supervision. Subjective and objective clinical evaluations of asthma status were made over 14 consecutive days. Detailed clinical history and clinical observations were made by an experienced staff, and a total of 2,663 pulmonary function tests were performed regularly three times daily and whenever a child sensed asthma symptoms. Patterns of obstruction were divided into large airway abnormalities and small airway abnormalities. There was a low concordance between standard large airway measures, such as the peak expiratory flow rate (PEFR) or the forced expiratory volume in 1 second (the FEV₁), and measures of small airway obstruction, such as the forced expiratory flow rate 25-75% (FEF_25–75). Normal PEFR measurements do not always indicate that all other pulmonary function measures are normal. In fact, 18% of children with a normal PEFR had abnormal FEF_25–75 values. Results demonstrated that the FEF_25–75 was the most specific and sensitive measure of airway obstruction. PEFR is widely used to monitor asthma symptoms objectively because it is technically simple to perform, relatively inexpensive, and helpful in most cases. It is, therefore, appropriate for asthma education programs to recommend PEFR as an objective measure to guide in making therapeutic decisions. Our data and clinical observations support the “Guidelines for the Diagnosis and Management of Asthma” of the NIH Health Asthma Education Program that suggest that children have more complete pulmonary function testing along with frequent PEFR measures. Many children may appear asymptomatic, while recording normal PEFR measures, and still having significant asthma. Repeated pulmonary function testing and evaluation of the pattern of respiratory obstruction aids in managing this challenging group. We recommend that efforts be made to develop a simple and inexpensive method of measuring FEF_25–75 that will allow this measurement to be made even at home. Pediatr Pulmonol. 1995; 20:372–379 . © 1995 Wiley-Liss, Inc.     

Nocturnal Reflux in Children and Adolescents with Persistent Asthma and Gastroesophageal Reflux

Background. A higher frequency of nocturnal gastroesophageal reflux (GER) in adult patients with respiratory symptoms has been demonstrated. The aim of this study was to determine the prevalence of nocturnal GER by using prolonged intraesophageal pH monitoring and compare it with spirometry results in children with persistent asthma. Methods. Thirty-eight patients with persistent asthma for at least 2 years were studied. Gastrointestinal symptoms suggestive of GER were considered as regurgitation, heartburn, and abdominal pain. All patients underwent prolonged intraesophageal pH study and spirometry. GER was considered positive when a reflux index (RI) was higher than 5%. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), forced mid-expiratory flow rate (FEF_{25 ? 75%}), and FEV₁/FVC ratio were measured. Results. Median age was 10 years of age (range 5 to 15) and 58% were male; GER prevalence was 47.3%. Median (range) of reflux index during supine and upright periods from GER patients were, respectively, 8.7% (3.2 to 23.6) and 10.5% (5.2 to 15.0) (p = 0.913), and only FEF_{25 ? 75%} was below the predicted value: 54.5% (39.4 to 96.9). Reflux index was not significantly correlated with FVC, FEV₁ and FEF_{25 ? 75%}. Conclusions. A high prevalence of GER was found in children and adolescents with persistent asthma, equally distributed in the supine (nocturnal) and upright positions. There was no correlation with pulmonary function test.     

The FEF25–75 and its Decline as a Predictor of Methacholine Responsiveness in Children

Background. Methacholine challenge (MCC) is an important diagnostic tool for asthma, especially in patients in whom routine pulmonary function testing (PFT) is normal or equivocal. The basis for a positive test per American Thoracic Society (ATS) guidelines is a methacholine concentration ≤ 16 mg/mL that causes a 20% decrease in forced expiratory volume in 1 second (FEV₁) (termed the PC20 for FEV₁). There is little information in the medical literature that utilizes other flow rates during MCC, including small airway function parameters such as the forced expiratory flow rate 25–75% (FEF_{25 ?75}). We question whether the FEF_{25 ?75} may be a useful parameter to monitor during MCC and whether it may be predictive of a positive MCC. Hypothesis. The baseline FEF_{25 ?75} and its decline during a MCC are useful in the interpretation of a MCC. Methods. We retrospectively analyzed all MCC performed at this institution between December 1998 and December 2006. Parameters reviewed included age, gender, race, weight, height, baseline PFT data including FVC, FEV₁, FEF_{25 ?75}, and forced expiratory time, methacholine PC20 for FEV₁, the relative changes from baseline for FEV₁ and FEF_{25 ?75} during the MCC, and clinical symptoms during the MCC. Results. A total of 532 MCC were completed during the 8-year study period in children 4 to 18 years of age. A total of 203 MCC (38%) were positive (defined by a PC20 ≤ 16 mg/mL) and 329 studies were negative (62%). The baseline % predicted FEF_{25 ?75} in positive MCC was 82.4 ± 21.9 vs. 98.7 ± 21.3 in the negative studies (p < 0.001). The FEF_{25 ?75}/FVC ratio in positive MCC was 0.82 ± 0.21 vs. 0.97 ± 0.23 in negative studies (p < 0.001). In the positive MCC, the decrease in FEF_{25 ?75} was much faster and of much greater degree than in the negative challenges. When a significant reduction in FEF_{25 ?75} was defined as greater than 10% by the second concentration of methacholine (0.25 mg/mL), the sensitivity for a positive MCC was 63%, the specificity was 71%, the positive predictive value was 57%, and the negative predictive value was 76%. A comparison of the baseline FEF_{25 ?75} to the PC20 for the positive MCCs revealed no statistical significance. Conclusions. The FEF_{25 ?75} and its decline during a MCC appear to be useful information and potentially predictive of a positive MCC. We suggest that the forced expiratory flow rate 25–75% (FEF_{25 ?75}) be considered as an adjunct to the FEV₁ to define a positive study.     

Normal spirometric reference values for Omani children and adolescents

OBJECTIVES: Normal lung function has been shown to be population specific. The aim of this study was to derive normal reference spirometric values for Omani children and adolescents. METHODOLOGY: Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), peak expiratory flow and forced mid-expiratory flow were measured in 837 healthy Omani school children aged 6-19 years. Multiple linear regression analysis was performed for each spirometric parameter against age, height and weight for boys and girls separately. RESULTS: All measured spirometric parameters increased with age and height and were significantly higher in boys than girls. Height explained the maximum variance for all parameters. After accounting for height in the prediction equations, the contribution of age and weight was minimal. The expiratory ratio (FEV(1)%FVC) was independent of age and height and its mean values (+/- standard deviation) were slightly higher in girls (91.1 +/- 6.1%) than boys (86.5 +/- 7.1%; P < 0.001). The predicted normal values of the subjects using the derived equations were between 5 and 10% lower than the respective values for subjects in Caucasian sample groups. CONCLUSION: The developed prediction equations can be used in clinical practice in Oman and can be considered for use in neighbouring Arab countries.     

Lung function values in healthy non-smoking urban adults in iran

BACKGROUND: The values of lung function tests (LFTs) are dependent on height, age, and sex. In addition, there is evidence of LFT variation in different ethnic groups. OBJECTIVE: We have therefore derived prediction equations for LFTs from a healthy, non-smoking, urban adult population in the city of Mashhad (northeast Iran). METHODS: Predicted equations for normal lung function have been derived from 572 healthy, non-smoking subjects including 326 men (height 154-195 cm) and 246 women (height 144-174 cm) aged 18-65 years. The subjects underwent measurement of spirometric flow and volume. The following variables were measured: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), maximal mid-expiratory flow (MMEF), peak expiratory flow (PEF) and maximal expiratory flow at 75, 50 and 25% of the FVC (MEF(75), MEF(50), and MEF(25), respectively). Regression analysis using height and age as independent variables was applied to provide predicted values for both sexes. RESULTS: There was a negative correlation between each lung function and age. The largest negative correlations were found for FEV(1) and FVC in men and women, respectively. All parameters correlated positively with height; the largest positive correlation was observed for FVC in both sexes. Comparison of LFTs derived from the equations of the present study showed significant differences with those of several previous studies. CONCLUSION: In this study, a set of LFT reference values and prediction equations for both sexes have been derived using a relatively large, healthy, non-smoking Iranian, adult population which was different from several other prediction equations.     

Reference values for spirometry,including vital capacity,in Japanese adults calculated with the LMS method and compared with previous values

BackgroundReference values for lung function tests should be periodically updated because of birth cohort effects and improved technology. This study updates the spirometric reference values, including vital capacity (VC), for Japanese adults and compares the new reference values with previous Japanese reference values.MethodsSpirometric data from healthy non-smokers (20,341 individuals aged 17–95 years, 67% females) were collected from 12 centers across Japan, and reference equations were derived using the LMS method. This method incorporates modeling skewness (lambda: L), mean (mu: M), and coefficient of variation (sigma: S), which are functions of sex, age, and height. In addition, the age-specific lower limits of normal (LLN) were calculated.ResultsSpirometric reference values for the 17–95-year age range and the age-dependent LLN for Japanese adults were derived. The new reference values for FEV₁ in males are smaller, while those for VC and FVC in middle age and elderly males and those for FEV₁, VC, and FVC in females are larger than the previous values. The LLN of the FEV₁/FVC for females is larger than previous values. The FVC is significantly smaller than the VC in the elderly.ConclusionsThe new reference values faithfully reflect spirometric indices and provide an age-specific LLN for the 17–95-year age range, enabling improved diagnostic accuracy. Compared with previous prediction equations, they more accurately reflect the transition in pulmonary function during young adulthood. In elderly subjects, the FVC reference values are not interchangeable with the VC values.