Lung volumes in healthy boys and girls, 6–15 years of age

Functional residual capacity (FRC), vital capacity (VC), and its subdivisions, inspiratory capacity (IC) and expiratory reserve volume (ERV) were measured by spirometry in 140 healthy children (74 boys and 66 girls), aged 6–15 years.Total lung capacity (TLC) and residual volume (RV) were calculated on the measured lung volumes.The coefficient of variation was calculated on three successive determinations of IC, ERV and VC and on the calculated values of TLC and RV. The coefficient of variation is considerably large in the RV determination (up to 8,5%) (reflecting the influence of the individual’s cooperation during the measurement of ERV) but it is small in the TCL determination (up to 1,9%) (reflecting the reproducibility of successive measurements of IC and FRC, which is satisfactorily small).A certain training effect could be observed on the final value of successive measurements of some lung volumes, but nevertheless, this individual adaption is slight (expressed in ml) and without practical clinical importance. The relationship between lung volumes (FRC, VC, TLC, RV) and height, weight, age, and surface area, respectively, have been calculated by regression calculations.Standing height is the best independent variable for predicting lung volume except in the determination of VC in girls. However, this discrepancy between the predictive equations of VC versus standing height in girls and the other equations, published in this study, is so slight, that it is of no practical importance.The calculated residual standard deviations of all lung volumes correspond to the values, published by Engström et al. (1956) but are quite different from the results of Geubelle and Breny (1969), whose results are much higher. This discrepancy has been discussed as being caused by the different populations, examined in these studies.FRC, VC, TLC, and RV are larger in boys than in girls, and these differences are significant. In absolute values (i. e., expressed in ml) these differences are small compared to the corresponding actual values of lung volumes. The growing rate of the lung volumes according to the standing height is similar in boys and girls.The mean values (and 2 SD) of the FRC/TLC as well as the RV/TLC ratios were calculated for both boys and girls, being almost identical to those, published in literature. There is a slight but significant change of these ratios in relation to age in boys but not in girls. This significant correlation to age in boys is so small, that it is negligible from the practical point of view.     

Lung volumes in healthy boys and girls, 6–15 years of age

Functional residual capacity (FRC), vital capacity (VC), and its subdivisions, inspiratory capacity (IC) and expiratory reserve volume (ERV) were measured by spirometry in 140 healthy children (74 boys and 66 girls), aged 6–15 years. Total lung capacity (TLC) and residual volume (RV) were calculated on the measured lung volumes. The coefficient of variation was calculated on three successive determinations of IC, ERV and VC and on the calculated values of TLC and RV. The coefficient of variation is considerably large in the RV determination (up to 8,5%) (reflecting the influence of the individual’s cooperation during the measurement of ERV) but it is small in the TCL determination (up to 1,9%) (reflecting the reproducibility of successive measurements of IC and FRC, which is satisfactorily small). A certain training effect could be observed on the final value of successive measurements of some lung volumes, but nevertheless, this individual adaption is slight (expressed in ml) and without practical clinical importance. The relationship between lung volumes (FRC, VC, TLC, RV) and height, weight, age, and surface area, respectively, have been calculated by regression calculations. Standing height is the best independent variable for predicting lung volume except in the determination of VC in girls. However, this discrepancy between the predictive equations of VC versus standing height in girls and the other equations, published in this study, is so slight, that it is of no practical importance. The calculated residual standard deviations of all lung volumes correspond to the values, published by Engström et al. (1956) but are quite different from the results of Geubelle and Breny (1969), whose results are much higher. This discrepancy has been discussed as being caused by the different populations, examined in these studies. FRC, VC, TLC, and RV are larger in boys than in girls, and these differences are significant. In absolute values (i. e., expressed in ml) these differences are small compared to the corresponding actual values of lung volumes. The growing rate of the lung volumes according to the standing height is similar in boys and girls. The mean values (and 2 SD) of the FRC/TLC as well as the RV/TLC ratios were calculated for both boys and girls, being almost identical to those, published in literature. There is a slight but significant change of these ratios in relation to age in boys but not in girls. This significant correlation to age in boys is so small, that it is negligible from the practical point of view.     

Respiratory function in children undergoing bone marrow transplantation.

We conducted a prospective study of respiratory function in children undergoing bone marrow transplantation (BMT) for onco-hematological disorders. Each child was evaluated before and 100 days after BMT. The investigations included clinical examination, chest X-ray, and pulmonary function tests (PFT) to determine: slow vital capacity (VC), functional residual capacity (FRC), total lung capacity (TLC), forced expiratory volume in 1 s (FEV1), carbon monoxide diffusing capacity (DLCO), ratio of residual volume (RV) to TLC, and FEV1/VC. The values obtained before and after BMT were compared to predicted values, and the post-BMT values were compared to the pre-BMT values (Student's t-test). From 1986 to 1995, 77 children underwent BMT, of whom 39 were available for testing. The pre-BMT VC (P = 0.0234) and DLCO (P < 0.0001) were lower and FRC higher (P < 0.0001) than predicted values. After BMT, the VC (P = 0.004), TLC (P = 0.044), and FEV1 (P = 0.012) were lower, and the RV/TLC ratio was higher (P = 0.043), compared with pre-BMT data. The observed respiratory abnormalities were not clinically relevant. The only identifiable risk factor for a decrease in lung function was age at BMT. This study shows that some lung dysfunction may be present before BMT and be further altered by BMT. This stresses the need for longitudinal respiratory monitoring and follow up to detect such dysfunctions and to insure an optimal treatment program for these children.     

Population based standards for pulmonary function in non-smoking adults in Singapore

Abstract Ethnic differences in lung function are well recognized, hence the use of normative data should therefore be based on reference equations that are derived specifically for different ethnic groups. We have collected data ( n =406) for population-based reference values of lung function from randomly selected samples of healthy non-smoking adults of both gender (aged 20–79 years) for each of the three major ethnic groups (Chinese, Malay and Indians) in Singapore. Lung function forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), FEV₁/FVC, diffusion capacity (transfer factor) for carbon monoxide (DLCO), total lung capacity (TLC), residual volume (RV), RV/TLC and functional residual capacity (FRC) was measured using standardization procedures and acceptability criteria recommended by the American Thoracic Society. Lung function values were predicted from age, height, weight, body mass index (BMI) and transformed variables of these anthropometric measures, using multiple regression techniques. Ethnic differences were demonstrated, with Chinese having the largest lung volumes and flow rates, and Indians the smallest. These prediction equations provide improved and additional (TLC, RV, RV/TLC, FRC) population-based reference values for assessment of pulmonary health and disease in Singapore     

Lung volumes in healthy Afro-Caribbean children aged 4-17 years

Lung volumes in healthy children differ according to their ethnic origin. We wished to determine if any differences in the lung volumes of Afro-Caribbean (AC) children from those predicted by Caucasian reference values disappeared if the results were related to sitting height or to 90% or 77% of lung volumes predicted for height from Caucasian reference values based on standing height. We took, as our working hypothesis, that it is inappropriate to use Caucasian reference values to interpret data from Afro-Caribbean children, and that ethnic-specific reference values are required. This was a prospective, observational study. Subjects included 80 AC children with a median age of 9 (range, 4.3-17.8) years. Standing and sitting height were measured. Lung volumes were measured by body plethysmography (total lung capacity, TLC(pleth); functional residual capacity, FRC(pleth); and vital capacity, VC(pleth)), helium gas dilution (functional residual capacity, (FRC(He)), spirometry (forced expiratory volume in 1 sec, FEV(1)), and forced vital capacity (FVC). The lung volumes of AC children correlated significantly with standing height, but differed significantly from values predicted from Caucasian reference values based on standing height (P < 0.05). Significant differences remained for TLC(pleth), FRC(pleth), FRC(He), RV(pleth), VC(pleth), FEV(1), and FVC when the results were related to sitting height or 90% or 77% of values predicted from Caucasian reference values based on height (P < 0.05). Lung volumes in Afro-Caribbean children should be compared to ethnic-specific reference values.     

Lung function in children and adolescents with tetralogy of Fallot after intracardiac repair

We studied lung function in 41 patients, aged 6–27 years, 1–5 years after intracardiac surgical repair (ICR) of tetralogy of Fallot (TOF) and about 5 years after the establishment of the Pediatric Cardiac Center in Prague. The measurements included vital capacity (VC). total lung capacity (TLC), functional residual capacity (FRC), residual volume (RV), forced expiratory flows (FEF), specific airway conductance (SGaw), lung recoil pressure (Pst), and specific static lung compliance (S_1st). Single or mutiple abnormal lung function parameters were found in 83% of patients. Lung function was not related to shunting operations prior to ICR, hemoglobin concentration, and hematocrit, and had no specific pattern. Pst at 100% TLC and 90% TLC declined with increasing age at ICR and at lung function testing, while SC, rose, as did the ratio FRC/TLC. Fifteen patients were studied before and after surgery. Single or multiple lung function tests were abnormal in 93% before and in 84% after ICR. After ICR the ratios FRC/TLC and also RV/TLC, FEF at 25% VC, and FEF at 60% TLC were less frequently abnormal, while Pst at 100% TLC and at 90% TLC, as well as SGaw and TLC, were more frequently abnormal after ICR. The results indicated a regression of smaller airway obstruction and lung hyperinflation after ICR. The evolution of abnormally compliant (emphysematous) lungs with growth of the patients might be a sign of permanent sequelae of early lung damage from abnormal pulmonary hemodynamics. Pediatr Pulmonol. 1993; 16:23–30. © 1993 Wiley-Liss, Inc.     

Pulmonary function in adolescents with ataxia telangiectasia

INTRODUCTION: Pulmonary complications are common in adolescents with ataxia telangiectasia (A-T), however objective measurements of lung function may be difficult to obtain because of underlying bulbar weakness, tremors, and difficulty coordinating voluntary respiratory maneuvers. To increase the reliability of pulmonary testing, minor adjustments were made to stabilize the head and to minimize leaks in the system. Fifteen A-T adolescents completed lung volume measurements by helium dilution. To assess for reproducibility of spirometry testing, 10 A-T adolescents performed spirometry on three separate occasions. RESULTS: Total lung capacity (TLC) was normal or just mildly decreased in 12/15 adolescents tested. TLC correlated positively with functional residual capacity (FRC), a measurement independent of patient effort (R2=0.71). The majority of individuals had residual volumes (RV) greater than 120% predicted (10/15) and slow vital capacities (VC) less than 70% predicted (9/15). By spirometry, force vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1) values were reproducible in the 10 individuals who underwent testing on three separate occasions (R=0.97 and 0.96 respectively). Seven of the 10 adolescents had FEV1/FVC ratios>90%. CONCLUSION: Lung volume measurements from A-T adolescents revealed near normal TLC values with increased RV and decreased VC values. These findings indicate a decreased ability to expire to residual volume rather then a restrictive defect. Spirometry was also found to be reproducible in A-T adolescents suggesting that spirometry testing may be useful for tracking changes in pulmonary function over time in this population.     

LUNG FUNCTION AND RESPIRATORY MUSCLE STRENGTH AFTER PROPRANOLOL IN THYROTOXICOSIS

Thirty-five thyrotoxic patients were assessed before treatment, after treatment with propranolol, and after antithyroid drugs. The first group of patients ( n = 17) performed the following tests at all three assessment points: forced expiratory volume in the first second (FEV,), vital capacity (VC), functional residual capacity (FRC), residual volume (RV), total lung capacity (TLC), maximal mid-expiratory flow rate (MMFR), diffusing capacity for carbon monoxide (DLCO), and maximum static inspiratory and expiratory mouth pressures (Plmax and PEmax). Arterial blood gas analysis was also performed for the first group of patients. No significant changes were seen either after propranolol or after antithyroid drugs in the FRC, RV, TLC, MMFR, DLCO, or blood gases. The remaining 18 patients, group 2, performed only the FEV₁, VC, Plmax, and PEmax tests at each assessment. The only index of respiratory function that improved significantly after propranolol was Plmax (from 46.5 ± 16.5 to 53.2 ± 22 cmH₂O, p < 0.01). This suggests that adrenergic excess may play a role in thyrotoxic inspiratory muscle weakness. After antithyroid drugs, Plmax, PEmax, FEV₁, and VC all increased significantly as expected. (Aust NZ J Med 1986; 16: 496–500.)     

Static lung volumes: reference values from a Latin population of Spanish descent.

BACKGROUND AND OBJECTIVES: The aim of this study was to develop a set of prediction equations and 90% confidence intervals for static lung volumes using the multibreath helium equilibration method from a sample of asymptomatic Caucasian subjects of Spanish descent. Moreover, these equations were compared with those of previous studies. METHODS: Measurements of static lung volumes using techniques recommended by the American Thoracic Society and the European Community for Steel and Coal were carried out on a selected sample of 591 healthy nonsmoking volunteers (305 men and 286 women) aged 18-88 years, living in the metropolitan area of Valencia, on the east coast of Spain. Multiple regression analysis using height, age and weight as independent variables were used to provide predicted values for both sexes. These reference values were compared with other sets of prediction equations reported in the literature using an independent sample of 69 subjects (32 men and 37 women). RESULTS: Simple linear regression equations using age, height and body weight predicted all the subdivisions of lung volumes (vital capacity, expiratory reserve volume (ERV), inspiratory capacity, functional residual capacity (FRC), residual volume (RV), total lung capacity (TLC), FRC/TLC and RV/TLC) as well as more complex equational models. The distribution of residuals fulfilled the assumptions of multiple regression analysis (independence, homoscedasticity and Gaussian distribution of residuals), except for ERV, using simple linear models. The derived equations did not differ significantly from most of the previously reported equations and were usually superior in their ability to predict the lung volumes. CONCLUSIONS: The use of the present prediction equations is recommended in the Latin population of Spanish descent and in populations with similar Caucasian characteristics.     

Postoperative pulmonary function in children. Comparison of scoliosis with peripheral surgery

We measured lung volumes, forced expirograms, and arterial blood gases in 2 groups of elective pediatric surgical patients (mean age, 11.4 +/- SD 2.8; n = 11, 12 operations) the day prior to surgery (control) and between the first and eighth postoperative days. The patients were Group I: peripheral surgery (n = 6) and Group II: reconstructive surgery for scoliosis (n = 5). The preoperative lung volumes and forced expiratory volume in one second were within the predicted normal range in both groups, except for a reduction in total lung capacity (TLC) and vital capacity (VC) in Group II. The postoperative lung volumes in Group I were not significantly different from the preoperative volumes. In group II, on postoperative Days 2 and 3, the lung volumes as a percent of preoperative volumes (mean +/- SEM) were VC, 44 +/- 11; functional residual capacity (FRC), 81 +/- 6; residual volume, 124 +/- 10; TLC, 61 +/- 10. Although the mean FRC returned to the preoperative volume by postoperative Days 5 and 6, the VC and its components remained reduced on postoperative Days 5, 6, and 8. We conclude that postoperative lung volume abnormalities are related to the site and magnitude of surgery and associated phenomena, such as pain, and preoperative respiratory function abnormalities.     

Differences in plethysmographic lung volumes. Effects of linked vs unlinked spirometry

Determination of absolute lung volumes in patients is most reliable when measured with body plethysmography. Many laboratories use data obtained with a spirometer not directly linked to the plethysmograph to calculate total lung capacity (TLC) and residual volume (RV) from thoracic gas volume (Vtg) measured at functional residual capacity (FRC) in the plethysmograph. The reliability of these calculations depends on the stability of FRC between these separate devices. We examined the differences in TLC and RV values calculated with linked and unlinked spirometers in 220 patients and found them statistically significant (p less than 0.05). Additionally, differences exceeding the 95 percent confidence intervals for repeated, linked determinations occurred in more than 5 percent of patients. The large-volume differences in TLC were often associated with differences in expiratory reserve volume (ERV) in the opposite direction, suggesting a shift in FRC. However, clinical diagnoses were infrequently (4/220) altered by these differences, and recognition of the shift in FRC should further reduce this error. Therefore, the unlinked method appears acceptable.     

50例健康老年人肺功能10年随访观察

目的为临床和基础研究提供健康老年人肺功能各项指标随增龄改变的参考资料。方法采用日本Ｃｈｅｓｔａｃ６５型肺功能检查仪,按常规方法进行肺功能检查。结果用力肺活量（ＦＶＣ）每年下降００３２Ｌ,第１秒用力呼气量（ＦＥＶ１）每年下降００３Ｌ,ＦＥＶ１占用力肺活量比值（ＦＥＶ１％）每年下降０１５１％,呼气流量峰值（ＰＥＦＲ）每年下降０１１８Ｌ／ｓ,最大呼气中段流量（ＭＭＥＦ）每年下降００４Ｌ／ｓ,最大通气量（ＭＶＶ）每年下降０８７６Ｌ,肺活量（ＶＣ）每年下降００４Ｌ,残气容积（ＲＶ）每年升高００３３Ｌ,功能残气量（ＦＲＣ）每年升高００３３Ｌ,残气容积／肺总量（ＲＶ／ＴＬＣ）每年升高０５９６％。戒烟组的健康老年人ＶＣ、ＦＶＣ、ＦＥＶ１、ＲＶ、ＲＶ／ＴＬＣ与从不吸烟健康老年人比较差异有显著性;不同年龄组的健康老年人肺功能下降不明显。结论肺功能各项指标随增龄而改变,健康老年人各年龄组肺功能改变不明显,吸烟对健康老年人肺功能改变有一定影响。     

Lung function in children and adolescents with idiopathic interstitial pulmonary fibrosis

Lung function of 65 patients who had idiopathic interstitial pulmonary fibrosis (IIPF) that had been treated with prednisone was evaluated by tests of ventilatory function, lung mechanics, and gas exchange at rest and during exercise. Ages on initial investigation ranged from 5 to 20 years. In 35 of 65 patients the studies were repeated an average of four times over a period of 1 to 9 years. Results of the first testing were as follows: vital capacity (VC)-significantly reduced in all patients; inspiratory capacity (IC)-significantly reduced in all patients; total lung capacity (TLC)-reduced in 91%; functional residual capacity (FRC)-reduced in 31%; residual volume (RV)-reduced in 6%; elastic recoil of the lungs (Pstl)-significantly increased in 97% at 100% TLC, significantly increased in 52% at 90% TLC, reduced in 68% at 60% TLC; 7) static compliance (Cst)-reduced in 83%; 8) dynamic compliance (Cdyn)-reduced in 88%; 9) specific airway conductance at FRC level (Gaw/TGVex)-significantly increased in 50%; 10) maximum expiratory flow rates at 60% TLC (Vmax 60% TLC, in TLC/s)-significantly reduced in 33%; 11) upstream airway conductance (Gus 60% TLC, in TLC/s/cm H2O)-reduced in 32%; 12) diffusing capacity of the lungs for carbon monoxide (DLco) related to body-surface area-abnormal in 58% (when corrected for lung size, i.e., DLco/TLC, abnormal in only 8%); 13) PaO2 at rest and after 6 minutes submaximal exercise-reduced in 25% and 63%, respectively. Changes in lung function that occurred with growth were assessed in terms of percentages of predicted values. Results showed that the VC and IC remained significantly reduced. An actual reduction of TLC, FRC, RV, breathing frequency, DLCO, and Pstl at 100% and 90% TLC was observed. Increases were seen in Pstl at 60% TLC, Gaw/TGVex, Vmax, and Cst. Indices of lung elasticity suggested that regions of fibrosis and emphysema had become present. Smaller patients were also noted to have stiffer lungs.     

Effects of bracing on lung function in idiopathic juvenile kyphosis

Although considerable information is available on the effects of bracing on lung function in kyphoscoliosis, there is a paucity of data on idiopathic juvenile kyphosis (IJK). The present study was designed to investigate the immediate effect of bracing on lung function in children and adolescents with mild-to-moderate IJK. Spirometry, measurement of lung volumes, and arterial oxyhemoglobin saturation (SaO(2)) were performed in 24 patients, 9-17 years of age, who were treated with a corrective brace for mild-to-moderate IJK (Cobb angle, 46-75 degrees ). Children were studied when braced and unbraced.When children were unbraced, mean percent predicted values (+/-standard deviation) for total lung capacity (TLC), vital capacity (VC), functional residual capacity (FRC), and forced expiratory volume in 1 sec (FEV(1)) were 100.0% (+/-13.0%), 92.7% (+/-14.2%), 108.2% (+/-20.4%), and 95.0% (+/-16.3%), respectively. With the brace on, significant reductions occurred in all lung function measurements: TLC decreased by 9.5% (P < 0.001), VC by 9.3% (P = 0.001), FRC by 14.2% (P = 0.005), and FEV(1) by 8.9% (P = 0.009). SaO(2) decreased from 96.2% (+/-1.6%) to 95.2% (+/-1.4%) (P = 0.027). An inverse relationship was observed between pre- and postbracing change in TLC and Cobb angle children (P = 0.021).Our findings indicate that corrective bracing in mild-to-moderate IJK results in mild lung restriction and a clinically insignificant drop in SaO(2). The effect of bracing on TLC decreases as the severity of kyphosis increases in these patients.     

Comparison of lung area by chest radiograph, with estimation of lung volume by helium dilution during prone and supine positioning in mechanically ventilated preterm infants: a pilot study

Measurement of lung volume may be useful in determining the degree of lung disease and for optimizing an infant's mechanical ventilator settings. A chest radiograph (CXR) is often used to estimate lung volume, because direct measurement, e.g., functional residual capacity (FRC), is neither practical nor possible in the neonatal intensive care unit. In supinely positioned infants, good correlation was found between lung area determined by CXR and lung volume, e.g., functional residual capacity (FRC). Whether this is true for the prone position is unknown. Since positioning may affect oxygenation and pulmonary function, we studied the relationship between lung area measured from CXR and FRC during both supine and prone positioning in 14 mechanically ventilated preterm infants. Lung area was determined from CXRs using computed radiography and FRCs obtained by helium dilution at end-expiration in both supine and prone positions. Reproducibility of lung area measurements was demonstrated by high correlations between two observers (R2 = 0.92 and 0.99 for supine and prone, respectively). When supine, lung area was 15.4 +/- 3.1 cm2, and FRC was 19.5 +/- 7.3 ml. In prone position, lung area was 16.7 +/- 4.2 cm2, and FRC 23.0 +/- 9.4 ml. There was a moderate to strong positive correlation between lung area and FRC for both positions (supine: r = 0.57, P < 0.03; prone: r = 0.63, P < 0.02). Lung area measured by computed radiography is a reproducible and practical method for estimating lung volume from routine chest X-rays in both supine and prone positions in mechanically ventilated preterm infants.     

Longitudinal Lung Volume Changes in Patients with Chronic Obstructive Pulmonary Disease

Background

The progression of lung hyperinflation in patients with chronic obstructive pulmonary disease (COPD) has not been studied in a long-term prospective cohort. We explored the longitudinal changes in lung volume compartments with the aim of identifying predictors of a rapid decline of the inspiratory capacity to total lung capacity ratio (IC/TLC).

Methods

The study population comprised 324 patients with COPD who were recruited prospectively. Annual rates of changes in pulmonary function, including forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), total lung capacity (TLC), functional residual capacity (FRC), residual volume (RV), vital capacity (VC), IC, and IC/TLC, were estimated using the random coefficient models.

Results

The mean annual rates of changes in pre- and post-bronchodilator FEV₁ were ?23.0 mL/year (p < 0.001) and ?26.5 mL/year (p = 0.004). The mean annual rates of changes in VC, IC, TLC, and IC/TLC were ?33.7 mL/year (p = 0.007), ?53.9 mL/year (p < 0.001), ?43.7 mL/year (p = 0.012), and ?0.65 %/year (p = 0.001), respectively. RV, FRC, and RV/TLC did not change significantly during the study period. Multivariate logistic regression analysis showed that a high modified Medical Research Council (MMRC) dyspnea scale score, a high Charlson comorbidity index value, and low post-bronchodilator FEV₁ were associated with rapid decline in IC/TLC.

Conclusion

MMRC dyspnea scale, post-bronchodilator FEV_1, and the Charlson comorbidity index at baseline were independent predictors of a rapid decline in IC/TLC.     

Adult-type pulmonary function tests in infants without respiratory disease

A new method that permits the measurement of adult-type maximal expiratory flow-volume curves and fractional lung volumes in sedated infants was recently described. The purpose of this study was to define the normal range for these new measures of pulmonary function in infants and young children. Measurements of forced expiratory flows and fractional lung volume were made on 35 occasions in 22 children (ages 3-120 weeks) without respiratory disease. Maximal expiratory flow-volume curves were measured by the raised lung volume, thoracoabdominal compression technique. Functional residual capacity (FRC) was measured plethysmographically. Measurements of total lung capacity (TLC), residual volume (RV), FRC, forced vital capacity (FVC), and forced expiratory flows at 25, 50, 75, 85, and between 25% and 75% of expired FVC (FEF(25), FEF(50), FEF(75), FEF(85), and FEF(25-75), respectively) all increased in relation to infant length (P<0.001). RV/TLC, FRC/TLC, and FEF(25-75)/FVC declined in relation to increasing length (P<0.001). The forced expiratory flow and fractional lung volume measurements using this method were similar to previously reported estimates using other methods. These estimates represent a reasonable reference standard for infants and young children with respiratory problems.     

Kurtosis and skewness of density histograms on inspiratory and expiratory CT scans in smokers

The aim of this study is to evaluate the relationship between lung function and kurtosis or skewness of lung density histograms on computed tomography (CT) in smokers. Forty-six smokers (age range 46?81 years), enrolled in the Lung Tissue Research Consortium, underwent pulmonary function tests (PFT) and chest CT at full inspiration and full expiration. On both inspiratory and expiratory scans, kurtosis and skewness of the density histograms were automatically measured by open-source software. Correlations between CT measurements and lung function were evaluated by the linear regression analysis. Although no significant correlations were found between inspiratory kurtosis or skewness and PFT results, expiratory kurtosis significantly correlated with the following: the percentage of predicted value of forced expiratory volume in the first second (FEV(1)), the ratio of FEV(1) to forced vital capacity (FVC), and the ratio of residual volume (RV) to total lung capacity (TLC) (FEV(1)%predicted, R = -0.581, p < 0.001; FEV(1)/FVC, R = -0.612, p < 0.001; RV/TLC, R = 0.613, p < 0.001, respectively). Similarly, expiratory skewness showed significant correlations with PFT results (FEV(1)%predicted, R = -0.584, p < 0.001; FEV(1)/FVC, R = -0.619, p < 0.001; RV/TLC, R = 0.585, p < 0.001, respectively). Also, the expiratory/inspiratory (E/I) ratios of kurtosis and skewness significantly correlated with FEV(1)%predicted (p < 0.001), FEV(1)/FVC (p < 0.001), RV/TLC (p < 0.001), and the percentage of predicted value of diffusing capacity for carbon monoxide (kurtosis E/I ratio, p = 0.001; skewness E/I ratio, p = 0.03, respectively). We conclude therefore that expiratory values and the E/I ratios of kurtosis and skewness of CT densitometry reflect airflow limitation and air-trapping. Higher kurtosis or skewness on expiratory CT scan indicates more severe conditions in smokers.     

Quantitative air-trapping analysis in children with mild cystic fibrosis lung disease

The purpose of this study was to compare quantitative computed tomography air trapping (AT) and pulmonary function measurements between subjects with mild cystic fibrosis lung disease (MCF; forced expiratory volume in 1 sec (FEV1) > 70% predicted) and normal age-matched controls. Quantitative AT measurements at different levels of expiration were evaluated. Ten subjects from the MCF group and 10 normal subjects underwent inspiratory and expiratory spirometer-triggered chest high-resolution computed tomography (HRCT) and pulmonary function tests. Six matched CT images were obtained at full inflation and at a lung volume near residual volume (nRV). Quantitative measurements of AT were determined by evaluating expiratory CT lung density and by the percent of segmented lung which demonstrated AT on expiratory scans. Percent AT was evaluated for all lung slices combined (global AT), and also by regional assessment. Additional comparisons of lung density and percent air trapping were made in 10 CF subjects with three matched axial HRCT images at lung volumes corresponding to full inflation, near functional residual capacity (nFRC), and nRV. All measurements of expiratory lung density in CF subjects were significantly lower and % AT significantly higher than normal controls. Significant correlations for all subjects were observed between % global AT and RV/TLC as well as forced expiratory flow between 25-75% of forced vital capacity (FEF(25-75)) % predicted. Pulmonary density measurements and % AT better discriminated differences between groups than PFTs. Measurements made on expiratory scans near FRC showed significantly higher values for AT than those made near RV.     

A normal FEV1/VC ratio does not exclude airway obstruction

BACKGROUND: A decreased forced expiratory volume in 1 s/vital capacity (FEV(1)/VC) ratio is the hallmark of the definition of airway obstruction. We recently suggested that a lung function pattern, we called small airways syndrome (SAOS), has a normal FEV(1)/VC and total lung capacity (TLC) and reflects obstruction of small airways. OBJECTIVES: To substantiate our hypothesis we measured and compared lung function tests including maximal expiratory flow rates (MEFR), sensitive indicators of airway obstruction, in SAOS subjects and in matched controls. METHODS: We selected 12 subjects with the pattern of SAOS, but without chronic lung or heart disease (average age: 40.7 +/- 7.8 years) and 36 age-matched subjects with normal lung function (42.8 +/- 6.3 years). We measured static and dynamic lung volumes, MEFR and lung diffusing capacity (DL(CO)). RESULTS: SAOS subjects were heavier smokers (p < 0.05) and body mass index was less than in control subjects (p < 0.01). Both FEV(1)/VC ratio and TLC were comparable in the two groups. However, FEV(1), VC, DL(CO), and MEFR were lower and residual volume (RV) and RV/TLC ratio were higher (p < 0.05) in the SAOS group than in the control one. Furthermore, the MEFR curve of the SAOS group was displaced to the left without any change in slope, suggesting premature airway closure. CONCLUSION: Our results suggest that a normal FEV(1)/VC ratio does not exclude airway obstruction. A decrease of FEV(1), provided TLC is normal, reflects small airway obstruction.