An isoflow-volume technique for assessing airway dynamics in children and adults

BACKGROUND: We propose a new approach to the measurement of small airway function as an alternative to recordings of maximal expiratory flow-volume (MEFV) curves. OBJECTIVES: A newly developed technique to record isoflow-volume (IFV) curves to be tested against maximal respiratory flow curves. METHODS: An isoflow whistle (IFW; Iflopen) measures the length of a constant expiration after full inspiration. The note of the whistle enables a subject to generate an even expiration, and the isoflow maintenance times at 1 l x s(-1) (IFMT1) and 2 l x s(-1) (IFMT2) are recorded. The accuracy and reproducibility of the IFV technique were evaluated in 17 healthy adults (age 17-55 years) and in 14 asthmatic children (age 6-14 years). Comparisons with standard lung function parameters, such as forced expiratory volume in 1 s (FEV1), maximal expiratory flow at 50% (MEF50) and 25% (MEF25) vital capacity and peak expiratory flow (PEF), obtained with a Wright Peakflow Meter were undertaken in 102 healthy (aged 8-14 years) and 101 asthmatic children (aged 6-17 years). A bronchial challenge test was performed in 13 asthmatic children. RESULTS: The expired volume measured by the IFW showed an acceptable agreement with that of a pneumotachograph (mean error of 4.32% for IFMT1 and 5.93% for IFMT2). In healthy and in asthmatic children, the correlations between FEV1 and IFMT1 or IFMT2 (r = 0.92 and 0.94, respectively) were found to be greater than that between FEV1 and PEF (r = 0.68). During bronchial challenge tests in 13 asthmatic children, the FEV1 decreased to 69% of baseline and IFMT1 to 58% of baseline. CONCLUSIONS: The IFV technique accurately measured airway obstruction and closely followed changes in standard parameters of the MEFV curve.     

Assessment of bronchial obstruction and its reversibility by shape indexes of the flow‐volume loop in asthmatic children

Asthma assessment by spirometry is challenging in children as forced expiratory volume in 1 s (FEV1) is frequently normal at baseline. Bronchodilator (BD) reversibility testing may reinforce asthma diagnosis but FEV1 sensitivity in children is controversial. Ventilation inhomogeneity, an early sign of airway obstruction, is described by the upward concavity of the descending limb of the forced expiratory flow‐volume loop (FVL), not detected by FEV1. The aim was to test the sensitivity and specificity of FVL shape indexes as β‐angle and forced expiratory flow at 50% of the forced vital capacity (FEF50)/peak expiratory flow (PEF) ratio, to identify asthmatics from healthy children in comparison to “usual” spirometric parameters. Seventy‐two school‐aged asthmatic children and 29 controls were prospectively included. Children performed forced spirometry at baseline and after BD inhalation. Parameters were expressed at baseline as z‐scores and BD reversibility as percentage of change reported to baseline value (Δ%). Receiver operating characteristic curves were generated and sensitivity and specificity at respective thresholds reported. Asthmatics presented significantly smaller zβ‐angle, zFEF50/PEF and zFEV1 (p ≤ .04) and higher BD reversibility, significant for Δ%FEF50/PEF (p = .02) with no difference for Δ%FEV1. zβ‐angle and zFEF50/PEF exhibited better sensitivity (0.58, respectively 0.60) than zFEV1 (0.50), and similar specificity (0.72). Δ%β‐angle showed higher sensitivity compared to Δ%FEV1 (0.72 vs. 0.42), but low specificity (0.52 vs. 0.86). Quantitative and qualitative assessment of FVL by adding shape indexes to spirometry interpretation may improve the ability to detect an airway obstruction, FEV1 reflecting more proximal while shape indexes peripheral bronchial obstruction.     

Comparison between peak expiratory flow rate and forced expiratory volume in one second in the evaluation of children suspected to have asthma

This study was conducted to evaluate whether forced expiratory volume in 1 second (FEV1) for the diagnosis of bronchial reactivity by means of the free-running exercise test and bronchodilator inhalation, could be appropriately replaced by simple measurements of peak expiratory flow rate (PEFR) in children.We studied 108 referred symptomatic children (due to chronic cough or wheezing) suspected to have asthma aged 5-14y. Forced breathing spirometry and the "Mini-Wright peak flow meter" tests were recorded before and fifteen minutes after the challenge with free- running exercise or bronchodilator (Salbutamol) inhalation, regarding the baseline FEV1 value (FEV1> 80% considered as normal).There was a high correlation between PEFR and FEV1 (in absolute value and percent predicted) measured before and after bronchodilator inhalation test (r = 0.48, P = 0.05) in comparison to the values referred to free- running exercise test (r = 0.26, P = 0.01)."forced breathing spirometry" and "Mini-Wright peak flow" cannot be used interchangeably for diagnosing asthma, and PEFR measurement should remain a procedure for monitoring and following up the patients.     

Comparison between peak expiratory flow and FEV(1) measurements on a home spirometer and on a pneumotachograph in children with asthma

BACKGROUND: The accuracy of electronic portable home spirometers has been demonstrated in vitro using computer-based waveforms. We assessed the agreement in vivo between measurements of lung function on an electronic spirometer (Koko Peak Pro) and those obtained by the gold standard, a hospital lung function laboratory pneumotachograph. METHODS: Fifty stable asthmatic children (33 boys), aged 6-17 years, performed peak expiratory flow (PEF) and forced expiratory volume in 1 sec (FEV(1)) measurements according to international guidelines on a portable home spirometer and on the hospital pneumotachograph in random order. All measurements complied to standard quality criteria. The PEF and FEV(1) values recorded with the home spirometer and on the hospital pneumotachograph were compared. RESULTS: All children performed reproducible high-quality measurements on both spirometers. PEF values on the home spirometer were considerably lower than on the laboratory pneumotachograph (95% CI for difference in PEF 14-30 L/min; P < 0.0001). Individual differences in PEF between the two devices could be >100 L/min. The FEV(1) values were slightly, but significantly, lower on the home spirometer (95% CI for difference in FEV(1) 0.02-0.1 L; P = 0.0018). CONCLUSIONS: A home spirometer provides reproducible and quality acceptable measures in children with asthma when performed under professional supervision and encouragement. Mean PEF and FEV(1) values recorded on this home spirometer are significantly lower than those on a hospital pneumotachograph, and individual differences may be large. Therefore, home spirometry may not be interchanged with pneumotachography in a lung function laboratory.     

Impulse oscillometry: a measure for airway obstruction

The impulse oscillometry system (IOS) was introduced as a new technique to assess airflow obstruction in patients who are not able to perform forced breathing maneuvers, e.g., subjects with cerebral palsy or severe mental retardation, and young children. This study evaluates the sensitivity and specificity of IOS parameters to quantify changes in airflow obstruction in comparison with forced expiratory volume in the first second (FEV(1)) and peak expiratory flow (PEF) measurements. Measurements of FEV(1), PEF, and resistance (R) and reactance (X) at frequencies of 5-35 Hz were performed in 19 children with asthma before, during, and after methacholine challenge and subsequent bronchodilatation. All parameters changed significantly during tests. Values of R5 and R10 correlated with FEV(1) (r = -0.71 and -0.73, respectively, P < 0.001), as did values of X5 and X10 (r = 0.52 and 0.57, respectively, P < 0.01). Changes in R preceded changes in PEF and FEV(1) during methacholine challenge. The area under the receiver operating characteristic (ROC) curve to predict a 15% fall in FEV(1) showed better sensitivity and specificity for R5 (area under the curve, 0.85) compared to PEF (0.79) or R10 (0.73). We conclude that IOS parameters can be easily used as an indirect measure of airflow obstruction. This might be helpful in patients who are not able to perform forced breathing maneuvers. In individual subjects, R values measured at 5 Hz showed to be superior to PEF measurements in the detection of a 15% fall in FEV(1).     

Correlation of airway obstruction and patient-reported endpoints in clinical studies.

To establish the correlation among asthma efficacy parameters over a long period, data from over 1,500 patients in two one-year asthma clinical trials with montelukast, a Cys-LT1 antagonist, were analysed. Airway obstruction measurements, forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF), were measured at clinic visits. Patients recorded daytime symptom score, "as-needed" beta-agonist use, and PEF on a daily basis. Relationships among these parameters at baseline and during the one-year treatment period were established by correlation analyses. Multiple correlations between the airway obstruction (FEV1 and PEF) and patient-reported measurements were evaluated by canonical correlation analysis. Pairwise correlations of the efficacy parameters over a one-year time period were stable. Canonical correlation between the airway obstruction and patient-reported asthma efficacy endpoints was low, indicating that each category of endpoints measures a distinctively different aspect of the disease. It appears that at least one endpoint from each category should be used in asthma clinical studies.     

Spirometry in children aged 3 to 5 years: reliability of forced expiratory maneuvers.

The aim of this study was to evaluate the feasibility and reproducibility of forced expiratory maneuvers during standard spirometric evaluation in preschool children. Among 570 young children attending our laboratory, we retrospectively selected 355 patients (14% 3-4-year-olds, 48% 4-5-year-olds, and 38% 5-6-year-olds) who carried out spirometric tests for the first time. The indications for such tests were history of asthma (70%), followed by chronic cough (20%) and other miscellaneous conditions (10%). Eighty-eight, 175, and 92 children performed one, two, and three acceptable tests respectively. Forced expired volume in 1 sec (FEV(1)) and forced vital capacity (FVC) did not differ significantly between attempts in children performing either two or three attempts. Forced expiratory time (FET), i.e., the total time required for the forced expiratory maneuver, was 1.7 +/- 0.1 sec (mean +/- SEM), and was no greater than 1 sec in 21.3% of all tested children. Consequently, FEV(1) does not appear to be well-suited to this age group. Forced expiratory volume in 0.50 and 0.75 sec (FEV(0.5), FEV(0.75)) were thus measured in the group of children performing three attempts (n = 92), and there was no statistical difference between attempts. In 267 children performing two or three tests, the ATS criteria of reproducing FEV(1) and FVC within 相似文献   

Forced expiratory parameters in healthy preschool children (3-6 years of age)

In a group of 173 healthy preschool children 3-6 years of age (body height, 90-130 cm; 102 boys and 71 girls) out of total 279 children examined, maximum expiratory flow-volume (MEFV) curves were recorded in cross-sectional measurements. The majority (62%) of preschool children were able to generate an MEFV curve as correctly as older children. From the curves, maximum expiratory flows at 25%, 50%, and 75 % of vital capacity (MEF(25), MEF(50), and MEF(75)), peak expiratory flow (PEF), forced expiratory volume in 1 sec (FEV(1)), forced vital capacity (FVC), and area delineated by MEFV curve (A(ex)) were obtained. The purpose of the study was to establish reference values of forced expiratory parameters in preschool children suitable for assessment of lung function abnormalities in respiratory preschool children. The values of the studied parameters increased nonlinearly and correlated significantly with body height (P < 0.0001); the correlation was much lower with age. A simple power regression equation was calculated for the relationship between each parameter and body height. A best-fit regression equation relating functional parameters and body height was a power function. Based on the obtained regression equations with upper and lower limits, we prepared tables listing reference values of forced expiratory parameters in healthy Caucasian preschool children, against which patients can be compared. No statistically significant gender differences were observed for MEF(25), MEF(50), MEF(75), PEF, FEV(1), FVC, and A(ex) by extrapolation. The reference values were close to those obtained in our older children. A decline of the ratios PEF/FVC, FEV(1)/FVC and MEF/FVC with increasing body height suggested more patent airways in younger and smaller preschool children.     

Reference values of the provocative concentrations of methacholine that cause 6% and 20% changes in forced expiratory volume in one second in a normal population

The provocative concentrations of inhaled methacholine that cause 6% (PC6) and 20% (PC20) falls in forced expiratory volume in one second (FEV1) were assessed in a population of 100 nonsmoking persons, equally distributed for sex, who ranged uniformly from 20 to 60 yr of age. These subjects had no respiratory symptoms, rhinitis, atopic history, or familial history of asthma. Single twofold dilutions of methacholine from 2 to 128 mg/ml were used; 81 and 34 subjects, respectively, showed PC6 and PC20 values less than 128 mg/ml. Eight subjects had PC20 values less than 16 mg/ml. In these subjects, the test had a good reproducibility (r = 0.92) when we repeated it, and serial measurements of peak expiratory flow rates did not suggest asthma. The fact that PC6 was related, although loosely, to baseline FEV, FEV/FVC, and forced expiratory flow during the middle half of the FVC (FEF) and that 4 of the 8 subjects with PC20 values less than 16 mg/ml had lower values of FEF might suggest that responsiveness to methacholine is partially linked with baseline airway caliber.     

Performance of forced expiratory manoeuvre in children.

The negative expiratory pressure (NEP) method has been previously used to assess the performance of forced vital capacity (FVC) manoeuvre in normal adults. The aim of the present study is to assess whether flow limitation is achieved during FVC manoeuvres in children aged 6-14 yrs. NEP (-10 cmH2O) was successfully applied in 177 normal children, the portion of FVC over which expiratory flow did or did not change with NEP being taken as effort-dependent and effort-independent, respectively. In all children peak expiratory flow (PEF) and forced expiratory volume in one second (FEV1) increased with NEP, indicating that PEF was in the effort-dependent portion of FVC. This portion decreased significantly with age (50-20% of FVC from 6-14 yrs). It is suggested that this mainly reflects the poorer coordination of specialized motor acts in younger children because of incomplete morphological and functional maturation of the relevant central nervous system (CNS) mechanisms. The results indicate that most unexperienced children aged 6-14 yrs can perform acceptable forced vital capacity manoeuvres, eventually achieving flow limitation over a portion of the forced vital capacity that increases with age. The negative expiratory pressure method can be used for online assessment of the performance of forced vital capacity manoeuvres and evaluation of treatment-related effects.     

Correlation between symptom score, wheeze, reversibility of pulmonary function tests and treatment response in asthma

Asthma management is a major concern because some asthmatic patients either do not respond or else hardly respond to treatment. Therefore in the present study, an attempt has been made to determine the predictors of treatment response in asthmatic patients. Thirty six asthmatic adults including 13 male and 23 female were studied during a 3 month treatment period. Asthma symptom score (SS) and wheezing were recorded before and after treatment. Pulmonary function tests (PFTs) including forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), maximal expiratory measured at the beginning and the end of the study. The increase in PFT values 10 mm after 200 ?,tg inhaled salbutamol (in percentage) was considered as reversibility in airway constriction. There were significant improvements in SS (p相似文献   

Assessment of a low-cost home monitoring spirometer for children

Electronic devices are now available to measure and store lung function parameters in the home. Before adopting a device for clinical or research use, it is important to validate it in the target patient group. The aim of this study was to assess a low-cost, portable, logging spirometer, the VM Plus (VM), against a standard laboratory Jaeger spirometer (JS) for use in children with respiratory disease. Seventy children with stable asthma or cystic fibrosis performed spirometry on the two devices, and results for peak expiratory flow (PEF) and forced expiratory volume in 1 sec (FEV(1)) were compared. Comparison was made both using the two devices separately (separate method) and with the devices connected in series (series method). Reproducibility of the VM measurements was also assessed. Correlation between measurements was close (R values: separate, PEF, 0.91; FEV(1), 0.94; series, PEF, 0.97, FEV(1), 0.99), but PEF readings on the VM Plus were substantially higher than with the JS (mean difference: separate, 54.8 L/min; series, 28.2 L/min). This reflects well-reported differences in PEF measurements between the Mini-Wright PEF meter, on which the VM Plus spirometer is based, and conventional spirometers. Limits of agreement (series method) were: PEF, -13.2 to +69.6 L/min; FEV(1), -0.03 to +0.19 L. Reproducibility of VM Plus measurements was acceptable: coefficient of variation for PEF was 4%; for FEV(1), 4.3%; coefficient of reproducibility for PEF, 39 L/min; for FEV(1), 0.26 L. The VM Plus provides reasonably accurate, reproducible measurements of PEF and FEV(1), but intrinsic bias, particularly in PEF measurement, needs to be taken into account. Its potential to document longitudinal changes in lung function in children with respiratory disease at home merits further study.     

An assessment of peak expiratory flow as a surrogate measurement of FEV1 in stable asthmatic children

We examined the relationship over 24 hours between percent-predicted values (PPV) of peak expiratory flow (PEF) and forced expiratory volume in one second (FEV1) in a group of 23 stable untreated asthmatic children 6 to 17 years of age by means of regression analysis as well as the percentage difference between the PPV of these two measurements. Although the Pearson correlation coefficient between the PPV was consistently high, ranging between 0.854 and 0.892, the assumption that such a finding substantiates the substitution of PEF for FEV1 is called into question. Over 50 percent of the subjects displayed a 10 percent or greater difference in the PPV between the two measurements, regardless of the time of day the two respiratory variable were determined, while over one-third of all subjects evidenced a 20 percent or greater discrepancy between the PPV of the two measures. While, on a group basis, there was no statistically significant difference in the mean percentage difference over 24 hours between the PPV of FEV1, when compared with the corresponding measurement of PEF, reliance on PEF alone in individual subjects may result in a false impression of the patency of the airways in comparison to the FEV1.     

Diagnostic value of negative expiratory pressure for airway hyperreactivity

STUDY OBJECTIVES: To examine the value of negative expiratory pressure (NEP) in the assessment of methacholine bronchoprovocation testing (BPT). DESIGN: Prospective, observational study. SETTING: Pulmonary function laboratory in a university hospital. PARTICIPANTS: Fifty-nine patients with chronic cough referred from outpatient clinics for methacholine BPT. METHODS: Each subject inhaled successive doubling concentrations of methacholine (from 0.049 to 25 mg/mL) until the FEV(1) decreased for > 20% or the maximum concentration of methacholine was inhaled. NEP was measured in the sitting position during tidal breathing before and after methacholine BPT. The FEV(1) and forced oscillation airway resistance (Rrs) and interrupter airway resistance (Rint) were also obtained simultaneously. A positive BPT result was defined as a fall in FEV(1) > or = 20%. RESULT: At baseline, only five patients had expiratory flow limitation as demonstrated by NEP (EFL-N). There were 39 patients with positive BPT results, and the other 20 patients had negative results. Among the BPT-positive patients, only 13 patients (33.3%) had EFL-N after methacholine challenge. The sensitivity indexes (absolute change/SD) of FEV(1), NEP, Rrs, and Rint were 16.0 +/- 9.6%, 1.1 +/- 1.6%, 3.8 +/- 4.5%, and 5.89 +/- 4.4% (mean +/- SD), respectively. The percentage changes in FEV(1) in BPT-positive patients correlated with the percentage changes in Rrs (r = 0.419, p = 0.008) and only marginally with the percentage changes in Rint (r = 0.307, p = 0.058), but not with the changes in EFL-N (r = 0.048, p = 0.77). CONCLUSION: These data suggest that NEP at sitting position is not sensitive in the assessment of methacholine bronchoprovocation as compared to FEV(1) and airway resistance measurements.     

Sensitivity of bronchial responsiveness measurements in young infants

OBJECTIVES: There is limited evidence on the preferred methods for evaluating lung function in infancy. The objective of this study was to compare sensitivity and repeatability of indexes of lung function in young infants during induced airway obstruction. METHODS: The study population consisted of 402 infants (median age, 6 weeks). Forced flow-volume measurements were obtained by the raised volume rapid thoracoabdominal compression technique and were compared with indexes of tidal breathing, measurements of transcutaneous oxygen (Ptco(2)), and auscultation during methacholine challenge testing. RESULTS: Ptco(2) was the most sensitive parameter to detect increasing airway obstruction during methacholine challenge, followed by forced expiratory volume at 0.5 s (FEV(0.5)). Both were superior to other indexes of forced spirometry as well as tidal breathing indexes and auscultation. Coefficients of variations for Ptco(2) and FEV(0.5) were 4% and 7%, respectively. CONCLUSIONS: Ptco(2) and FEV(0.5) are the most sensitive parameters for measurement of bronchial responsiveness in young infants. Measurements of baseline lung function should preferably be made using FEV(0.5.) Measurements of bronchial responsiveness are best assessed using Ptco(2), which may be performed in nonsedated infants and improve feasibility of future studies on lung function in infancy.     

Spirometry in young children: should computer-animation programs be used during testing?

Currently, computer-animation programs are frequently used to instruct and stimulate young children in performing maximal expiratory flow/volume (MEFV) curves. The reproducibility and maximal performance of MEFV manoeuvres with and without the use of two computer-animation programs (the "candles" and the "balloon" programs) were evaluated. Eighty-eight children, aged 4-8 yrs, were randomly assigned to one of the two animation programs. All children performed two series of at least three technically acceptable curves, one series with the incentive and one without, in random order. With the use of computer-animation programs, a lower proportion of children were able to fulfil international criteria for forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) reproducibility. The use of incentives improved reproducibility and performance of peak expiratory flow (PEF). Performance of FVC decreased significantly in 6-8-yr-old children using the animation programs. Training with a program for a short period of time before the formal lung-function test may be valuable. According to the results, however, the use of these programs during tests under the guidance of an experienced lung-function technician cannot be routinely recommended because of possible deteriorating effects on reproducibility and performance of forced expiratory manoeuvres.     

Bronchial responsiveness, oscillations of peak flow rate and symptoms in patients with mitral stenosis.

To better characterize airway hyperresponsiveness reported in cardiac patients questionnaire-recorded symptoms, bronchial responsiveness to methacholine (Mch) and to ultrasonically nebulized distilled water (UNDW), diurnal oscillations of peak expiratory flow (PEF) rate were evaluated in 32 patients with moderate mitral stenosis. Twenty patients were responsive to Mch (defined as provocative dose producing a 20% fall in forced expiratory volume in one second (PD20 FEV1) less than 3.2 mg) (geometric mean PD20 FEV1 851 +/- 154 micrograms SE). Only two patients showed a fall in FEV1 greater than 20% after UNDW challenge. Patients responsive to Mch challenge had lower FEV1 as percentage of vital capacity (FEV1/VC) (80 +/- 4.8 vs 83 +/- 3.8%, p less than 0.05), higher coefficient of variation of PEF (CV-PEF) (7.1 +/- 2.8 vs 5 +/- 2.4, p less than 0.05) and higher prevalence of wheeze (70 vs 25%, p less than 0.05) in comparison with patients non-responsive to Mch challenge. CV-PEF was significantly related to FEV1 (r = 0.347, p less than 0.05) and maximal expiratory flow at 50% expired volume (MEF50) (r = 0.405, p less than 0.05). The probability of responding to Mch bronchial challenge increased proportionally with the increase in CV-PEF and the decrease in FEV1, FEV1/VC and MEF50. Airway hyperresponsiveness of patients with mitral stenosis seems to be more similar to that reported in bronchitic than in asthmatic patients.     

Pulmonary testing using peak flow meters of very low birth weight children born in the perisurfactant era and school controls at age 10 years

We determined lung function at age 10 years in very low birthweight (VLBW, 相似文献   

Forced expiratory manoeuvres in children: do they meet ATS and ERS criteria for spirometry?

The aim of this study was to evaluate the applicability of American Thoracic Society and European Respiratory Society criteria for spirometry in children. Maximal expiratory flow/volume (MEFV) measurements from 446 school-age children, experienced in performing MEFV manoeuvres, were studied and acceptability (start-of-test (backward extrapolated volume as a percentage of forced vital capacity (FVC) ([Vbc%FVC) or as an absolute value (Vbe), end-of-test (forced expiratory time (FET)) and reproducibility criteria (absolute and percentage difference between best and second-best FVC and forced expiratory volume in one second (FEV1) (deltaFVC, deltaFVC %, deltaFEV1 and deltaFEV1 %)) were applied to these manoeuvres. The Vbe%FVC criterion was met by 91.5%, the Vbe <0.15 L criterion by 94.8% and the Vbe <0.10 L by 60.1% of children. Vbe <0.15 L appeared to be a more useful parameter than Vbe%FVC. The FET criterion was met by only 15.3% of children. deltaFVC <0.2 L and deltaFEV1 <0.2 L were met by 97.1% and 98.4%, and deltaFVC <0.1 L and deltaFEV1 <0.1 L by 79.8% and 84.3% of the children, respectively. These criteria appeared to be less useful compared to percentage criteria (deltaFVC % and deltaFEV1 %). Even experienced children did not meet all international criteria for spirometry. However, most of their MEFV curves are useful for interpretation. Based on the performance of these children, a re-evaluation of criteria for maximal expiratory flow/volume measurements in children is proposed.     

Large airway size, lung size, and maximal expiratory flow in healthy nonsmokers

It has been postulated that airway size and lung size may be dissociated because of developmental differences between the tracheobronchial tree and the pulmonary parenchyma (dysanapsis). To test this hypothesis, we compared measurements of airway size (diameters, cross-sectional area, length and volume of the trachea, diameter and cross-sectional area of the mainstem bronchi) and lung size (total lung capacity, thoracic diameters, lung length), as determined from plain chest radiographs in 79 male and 86 female healthy nonsmokers. In both groups of subjects, the correlation between indexes of airway size and lung size was low. Airway size was not significantly different between men and women, when standardized for lung size. Tracheal diameter and length tended to increase with age. To assess the value of airway size measurements in the prediction of maximal expiratory flow, we compared tracheal and bronchial size with FVC, FEV 0.5, FEV1, and mean forced expiratory flow during the middle half of VC. The correlation between airway size and spirometric indexes was very low. Multiple regression analysis showed that the use of airway size variables in addition to the age and height variables did not substantially improve the prediction of maximal expiratory flow. Our results are consistent with the dysanapsis hypothesis, but they suggest that the introduction of radiologic estimates of large airway size in the prediction equations relating maximal expiratory flow to age and height is not justified, at least in the general population.