Lung Function Variables Research Articles

Lung Function Variability in Children and Adolescents

Lung Function Variability in Children and Adolescents

Seasonal variability of lung function and Asthma Quality of Life Questionnaire Scores in adults with uncontrolled asthma

IntroductionAsthma exacerbations spike in the spring and autumn months, yet the seasonal variation of asthma symptoms and lung function is poorly studied.MethodsSeasonal variation of lung function, rescue medication use and...

Nutrient intake is a predictor of lung function in obese asthmatic adolescents undergoing interdisciplinary therapy.

Asthma-obesity is a multifactorial disease with specific asthma phenotypes that aggravate due to overweight and an unbalanced diet. Furthermore, obese asthmatic patients are corticotherapy-resistant. Therefore, the aims of the present study were to evaluate the effects of an interdisciplinary intervention on food consumption, body composition, lung function and adipokines in asthmatic and non-asthmatic obese adolescents and to investigate the influence of nutrients on lung function. Obese non-asthmatic (n 42) and obese asthmatic (n 21) adolescents of both sexes were enrolled in the present study. Food intake, adipokine levels, body composition, asthma symptoms and lung function were assessed across the study. After the intervention of 1 year, there was a reduction (P ≤ 0·01) in BMI, body fat percentage, visceral and subcutaneous fat and an increase (P ≤ 0·01) in lean mass and all lung function variables in both groups, except the relation between forced expiratory volume in 1 s and forced vital capacity (FEV1:FVC) in non-asthmatic patients. Moreover, both groups decreased lipid and cholesterol consumption (P ≤ 0·01). The highest energy consumption (β = -0·021) was associated with lower values of FVC. Similarly, carbohydrate consumption (β = -0·06) and cholesterol were negative predictors (β = -0·05) in FEV1:FVC. However, the consumption of Ca (β = 0·01), fibres (β = 1·34) and vitamin A (β = 0·01) were positive predictors of FEV1:FVC. Asthma-obesity interdisciplinary treatment promoted an improvement on food consumption and lung function in adolescents and demonstrated that the consumption of nutrients influenced an increase in lung function.

Investigating the relationships among lung function variables in chronic obstructive pulmonary disease in men.

BackgroundIn patients with chronic obstructive pulmonary disease (COPD), the independent contributions of individual lung function variables to outcomes may be lower when they are modelled together if they are collinear. In addition, lung volume measurements may not be necessary after spirometry data have been obtained. However, these hypotheses depend on whether forced vital capacity (FVC) can predict total lung capacity (TLC). Moreover, the definitions of hyperinflation and air trapping according to lung function variables overlap and need be clarified. Therefore, the aim of this study was to evaluate the relationships among various lung function parameters to elucidate these issues.MethodsDemographic data and 26 parameters of full lung function were measured in 94 men with COPD and analyzed using factor and correlation analyses.ResultsFactor analysis revealed five latent factors. Inspiratory capacity (IC)/TLC and residual volume (RV)/TLC were most strongly correlated with all other lung volumes. IC/TLC, RV/TLC, and functional residual capacity (FRC)/TLC were collinear and were potential markers of air trapping, whereas TLC%, FRC%, and RV% were collinear and were potential markers of hyperinflation. RV/TLC >0.4 (or IC/TLC <0.4) was comparable with the ratio of forced expiratory volume in one second (FEV1) and FVC <0.7. FVC% and FEV1% were poorly correlated with TLC%. The correlation study showed that TLC%, RV/TLC, and FEV1% could be used to represent individual latent factors for hyperinflation, air trapping, inspiration, expiration, and obstruction. Combined with diffusion capacity%, these four factors could be used to represent comprehensive lung function.ConclusionsThis study identified collinear relationships among individual lung function variables and thus selecting variables with close relationships for correlation studies should be performed with caution. This study also differentiated variables for air trapping and lung hyperinflation. Lung volume measurements are still required even when spirometry data are available. Four out of 26 lung function variables from individual latent factors could be used to concisely represent lung function.

Variability of lung function and respiratory muscles power in healthy and asthmatic subjects

Airway function is one of the many biologic functions that exhibit circadian variability over 24-h periods. Studies of circadian variability of lung function in normal subjects as well as asthmatics are particularly scarce, and those of MEP and MIP are unknown. The aim of this study to determine circadian variation in lung function (FVC, FEV1 and PEFR) and respiratory muscle pressures(MEP and MIP) for measurement of respiratory muscle power at 6:00am (early morning),12:00midday, 6:00pm( evening) and 12:00 midnight in healthy subjects and in patients with mild asthma at 6:00am and 6:00pm , to elaborate on the possibility of using MEP and MIP variability as a new diagnostic test for asthma. This is a cross sectional study performed in Khartoum, the capital of Sudan during December 2010. Thirty healthy, symptoms free non smokers normal subjects aged 20-64 years selected randomly and 15 mild asthmatics, clinically free during the time of study aged 19-49 years were included in the study. There is significant drop in healthy subjects early in the morning compared to 6:00pm, the drop in FVC was 9.75%, in FEV1 was 8.79%, in PEFR was 8.44%, in MEP was 10.04%, and in MIP was 17.57%. There is also significant drop in asthmatics early in the morning in MEP and MIP (21.76%, 27.57% respectively), is comparable to FEV1 (22.56%) and PEFR (23.86%). The sensitivity and specificity of variability for MEP (53%, 77%) and MIP (60%, 63%) comparable to sensitivity and specificity of FEV1 variability (40%, 86%) and PEFR variability (46%, 73%). The obtained comparable results of MEP, MIP variability to FEV1, PEFR variability in normal and asthmatic subjects could imply that MEP &amp; MIP can be used in assessing airway calibre as in asthma. The study concluded that MEP &amp; MIP variability could be sensitive tests to confirm asthma diagnosis.

Clinical efficacy of bronchodilators in equine asthma: Looking for minimal important difference.

Airway obstruction is the main trait of severe equine asthma that affects respiratory function and elicits detrimental effects on clinical presentation. Only few and underpowered clinical studies have investigated the impact of improvement in lung function induced by bronchodilators on the clinical signs of asthma-affected horses. To identify the minimal important difference (MID) in lung function elicited by bronchodilator leading to a meaningful improvement in clinical signs. Pairwise meta-analysis and meta-regression analysis. Literature searches were performed for studies that investigated the effect of bronchodilator therapy on lung function and clinical condition of asthmatic horses. The relationship between the change in lung function variables and clinical score was analysed via random-effect meta-regression. One-point change of the Improved clinically Detectable Equine Asthma Scoring System (IDEASS) score was used to identify the MID. A significant (P<0.05) relationship was found between the changes in IDEASS score and maximum change in transpulmonary pressure (ΔPplmax ) or pulmonary resistance (RL ). Since only the model resulting for RL passed through the origin (Y-intercept when X=0: -0.31, 95% CI -0.75 to 0.14), this variable was used to identify the MID correlated with a meaningful improvement in clinical signs. The resulting MID value was a change in RL of 0.63cmH2 O/L/s (95% CI 0.33-0.94), representing the slope of meta-regression model (high quality of evidence). No long-term studies investigated the effect of bronchodilator agents on both lung function and clinical signs in asthmatic horses. In conclusion, bronchodilator pharmacotherapy in equine asthma elicits clinically meaningful effect when RL increases ≥1cmH2 O/L/s, a value indicating the MID. Assessing the MID based on change in RL may improve the quality of evidence and the scientific impact of future clinical trials as it extends beyond the simple, and limiting, evaluation of statistical significance.

Improvements in functional and cognitive status following short-term pulmonary rehabilitation in COPD lung transplant recipients: a pilot study.

BackgroundPulmonary rehabilitation (PR) following lung transplantation (LTx) is considered part of the optimal treatment in chronic obstructive pulmonary disease (COPD) for favourable post-operative outcomes. We investigated the effects of a PR intervention in the post-transplant phase with regard to lung function, exercise responses and cognitive function in COPD LTx recipients.Methods24 COPD LTx recipients (mean±sd forced expiratory volume in 1 s 75±22% predicted) were assigned to a comprehensive 3-week inpatient PR programme. Changes from PR admission to discharge in lung function variables, 6-min walk test-derived outcomes and cognitive function were assessed and examined for several factors. The magnitude of changes was interpreted by effect size (ES).ResultsIn response to the PR intervention, LTx recipients had improved lung function with regard to diffusing capacity of the lung for carbon monoxide (+4.3%; p=0.012) and static hyperinflation (residual volume/total lung capacity −2.3%; p=0.017), increased exercise capacity (6-min walk test +86 m; p<0.001), and had small to large improvements (ES range 0.23–1.00; all p≤0.34) in 50% of the administered cognitive tests. Learning skills and memory ability presented the greatest benefits (ES composite scores 0.62 and 0.31, respectively), which remained similar after stratification by single or bilateral LTx and sex.ConclusionsPR is an effective treatment for LTx recipients in the post-transplant phase, improving lung function, exercise responses, and domains of cognitive function of learning, memory and psychomotor speed. PR may facilitate the course of post-operative treatment and should be recommended in LTx.

Subterranean Pulmonary Rehabilitation in Chronic Obstructive Pulmonary Disease.

Pulmonary rehabilitation (PR) has been recommended as an integral part of treatment for patients with chronic obstructive pulmonary disease (COPD). Climate therapy in salt mine chambers has been found of benefit in chronic respiratory diseases. The study compares long-term effects of underground PR in the Wieliczka Salt Mine with that conducted on the surface. There were 42 COPD patients enrolled in the study, with FEV1/FVC <0.7 predicted and post-bronchodilator reversibility <12%, randomized into pulmonary rehabilitation in the mine (Group I, n=23) and PR on the surface (Group II, n=19). The outcomes consisted of lung function variables, exercise performance (6-min walk test - 6MWT), dyspnea (mMRC), and compliance with the disease and quality of life (COPD Assessment Test - CAT) and BODE index, compared at baseline (P0), end (P1), and 6months after pulmonary rehabilitation (P2). The findings were that subterranean pulmonary rehabilitation significantly reduced CAT score (p<0.001), BODE index (p=0.004), and dyspnea (mMRC) (p=0.001) and increased distance in 6MWT (p<0.001), compared with its equivalent conducted on the surface. Further, beneficial effect of subterranean treatment was sustained during the following half a year as opposed to the effect noticed on patients treated on the surface. We conclude that subterranean pulmonary rehabilitative treatment reduces symptoms and improves exercise tolerance to a greater and sustained extent, compared to a similar treatment on the surface, in patients suffering from COPD.

Factors affecting spirometry reference range in growing children.

Objectives:To find out the association of weight, height and age with spirometry variables and to generate a regression equation by taking weight as an independent variable beside age and height among children and adolescents of Karachi.Methods:A modified form of ISSAC questionnaire was used. The spirometry variables recorded were Forced vital capacity (FVC), Forced expiratory volume in 1 second (FEV1), FEV1/FVC, Peak expiratory flow rate (PEF), Forced expiratory flow between 25% and 75% expired volume (FEF25-75). A person’s correlation coefficient among boys and girls were calculated for all spirometry variable considering age, height and weight as independent variables. The linear regression models were calculated.Results:The results reported a linear correlation of lung function variables with all three independent variables (i.e. p-value = 0.000), in which age and height manifested a strong positive correlation while weight reported a moderately significant correlation. All spirometry variables such as FVC, FEV1, PEF and FEF25-75 reported a significant coefficient of dependency and coefficient of correlation individually with age, height and weight.Conclusion:It is concluded that beside age, height and weight both also have significant correlation with lung volumes so these should be taken into account when using spirometry as a diagnostic test.

The respiratory physiome: Clustering based on a comprehensive lung function assessment in patients with COPD.

BackgroundWhile spirometry and particularly airflow limitation is still considered as an important tool in therapeutic decision making, it poorly reflects the heterogeneity of respiratory impairment in chronic obstructive pulmonary disease (COPD). The aims of this study were to identify pathophysiological clusters in COPD based on an integrated set of standard lung function attributes and to investigate whether these clusters can predict patient-related outcomes and differ in clinical characteristics.MethodsClinically stable COPD patients referred for pulmonary rehabilitation underwent an integrated assessment including clinical characteristics, dyspnea score, exercise performance, mood and health status, and lung function measurements (post-bronchodilator spirometry, body plethysmography, diffusing capacity, mouth pressures and arterial blood gases). Self-organizing maps were used to generate lung function based clusters.ResultsClustering of lung function attributes of 518 patients with mild to very severe COPD identified seven different lung function clusters. Cluster 1 includes patients with better lung function attributes compared to the other clusters. Airflow limitation is attenuated in clusters 1 to 4 but more pronounced in clusters 5 to 7. Static hyperinflation is more dominant in clusters 5 to 7. A different pattern occurs for carbon monoxide diffusing capacity, mouth pressures and for arterial blood gases. Related to the different lung function profiles, clusters 1 and 4 demonstrate the best functional performance and health status while this is worst for clusters 6 and 7. All clusters show differences in dyspnea score, proportion of men/women, age, number of exacerbations and hospitalizations, proportion of patients using long-term oxygen and number of comorbidities.ConclusionBased on an integrated assessment of lung function variables, seven pathophysiological clusters can be identified in COPD patients. These clusters poorly predict functional performance and health status.

Reference values for lung function screening in 10- to 81-year-old, healthy, never-smoking residents of Southeast China.

No official spirometry reference values for Chinese are available.To establish new Chinese reference values and prediction equations for lung parameters in Chinese individuals of 10 to 81 years of age.Pulmonary functions were measured according to the American Thoracic Society criteria in 1457 subjects from the Zhejiang coastal province (China). The subjects were 10 to 81 years of age, nonsmokers, and without chronic or acute diseases. Multiple stepwise linear regression analysis was performed for each parameter against age, height, weight, and body mass index (BMI; kg/m2) for males and females separately.Most lung function variables were nonlinear with age and showed a plateau in younger adults, with a decline after 31 to 35 years. All spirometric data of men were higher than those of women except breathing frequency and forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC). All measured lung function parameters were strongly correlated to age, height, weight, and BMI. The highest correlation being to height in both men and women except for tidal volume and expiratory reserve volume among women. Based on previous studies, Caucasians men from the USA and Switzerland had higher FVC and FEV1 than in the present study, but only slightly higher than American blacks, British, Pakistani, and Singapore; an inverse trend was observed for Malay and Indians. Similar relationships were observed for women. The relationship between height and lung function parameters was nonlinear, with the variance of lung function parameters increasing with increasing height. For each sex, the z scores differed significantly by BMI (P < .001).This study provides spirometry equations that can be used for Chinese individuals.

SLC26A9 Gene Is Associated With Lung Function Response to Ivacaftor in Patients With Cystic Fibrosis.

Ivacaftor is a drug used to treat cystic fibrosis (CF) patients carrying specific gating CFTR mutations. Interpatient variability in the lung response has been shown to be partly explained by rs7512462 in the Solute Carrier Family 26 Member 9 (SLC26A9) gene. In an independent and larger cohort, we aimed to evaluate whether SLC26A9 variants contribute to the variability of the lung phenotype and if they influence the lung response to ivacaftor. We genotyped the French CF Gene Modifier Study cohort (n = 4,840) to investigate whether SLC26A9 variants were involved in the lung phenotype heterogeneity. Their influence in the response to ivacaftor was tested in the 30 treated patients who met the inclusion criteria: older than 6 years of age, percent-predicted forced expiratory volume measured in 1 s (FEV1pp) in the 3 months before treatment initiation ranging between 40 and 90%. Response to treatment was determined by the change in FEV1pp from baseline, averaged in 15–75 days, and the 1st-year post-treatment. We observed that SLC26A9 variants were not associated with lung function variability in untreated patients and that gain of lung function in patients treated with ivacaftor was similar to clinical trials. We confirmed that rs7512462 was associated with variability in ivacaftor-lung response, with a significant reduction in lung function improvement for patients with the C allele. Other SLC26A9 SNPs also contributed to the ivacaftor-response. Interindividual variability in lung response to ivacaftor is associated with SLC26A9 variants in French CF patients. Pharmacogenomics and personalized medicine will soon be part of CF patient care.

Effect of Altitude and Duration of Stay on Pulmonary Function in Healthy Indian Males

&lt;p&gt;The study was carried out with the objective to investigate the effect of varying altitude and duration of exposure on blood pressure, heart rate and lung function parameters in healthy Indian soldiers after adopting proper acclimatization schedule. For this purpose 17 soldiers of Indian Army, weight and height matched, were studied after obtaining written consent. Recording of Blood pressure (systolic and diastolic), heart rate and lung function variables (FVC, FEV1, FEV1/FVC%, MVV, FEF25-75%, MEF 25%, MEF 50%, MEF 75%, PEF) were measured at basal (290m), 800m, 3200m (day 10 and day 20) and upon de-induction. Our results demonstrate that with increasing altitude FVC declined, FEV1 did not change and due to these changes FEV1/FVC% increased. Expiratory flow rates including MEF 25%, MEF50% MEF 75%, PEF and mean expiratory flow rate (FEF25-75%) increased upon induction to high altitude. This increase may be due to reduction in air density causing less air resistance which accelerates lung emptying. Though the increase upon induction in all the values was transient and returned to baseline values after de-induction. MVV reflecting respiratory muscle function increased significantly upon induction to altitude in our study and returned to basal values upon de-induction. Understanding respiratory system in mountainous regions and its further correlation with other systems pertaining to acclimatization could help in laying step in unveiling mechanism of human high altitude adaptation.&lt;/p&gt;

Lower Distending Pressure Improves Respiratory Mechanics in Congenital Diaphragmatic Hernia Complicated by Persistent Pulmonary Hypertension

To investigate the effects of distending pressures on respiratory mechanics and pulmonary circulation in newborn infants with congenital diaphragmatic hernia (CDH) and persistent pulmonary hypertension (PPHN). In total, 17 consecutive infants of ≥37 weeks of gestational age with CDH and PPHN were included in this prospective, randomized, crossover pilot study. Infants were assigned randomly to receive 2 or 5 cmH2O of positive end-expiratory pressure (PEEP) for 1 hour in a crossover design. The difference between peak inspiratory pressure and PEEP was kept constant. Respiratory mechanics, lung function, and hemodynamic variables assessed by Doppler echocardiography were measured after each study period. At 2 cmH2O of PEEP, tidal volume and minute ventilation were greater (P < .05), and respiratory system compliance was 30% greater (P < .05) than at 5 cmH2O. PaCO2 and ventilation index were lower at 2 cmH2O than at 5 cmH2O (P < .05). Although preductal peripheral oxygen saturation was similar at both PEEP levels, postductal peripheral oxygen saturation was lower (median [range]: 81% [65-95] vs 91% [71-100]) and fraction of inspired oxygen was greater (35% [21-70] vs 25% [21-60]) at 5 cmH2O. End-diastolic left ventricle diameter, left atrium/aortic root ratio, and pulmonary blood flow velocities in the left pulmonary artery were lower at 5 cmH2O. After surgical repair, lower distending pressures result in better respiratory mechanics in infants with mild-to-moderate CDH. We speculate that hypoplastic lungs in CDH are prone to overdistension, with poor tolerance to elevation of distending pressure.

PD26 Principal Component Approximation: Canadian Health Measures Survey

Introduction:Principal component analysis (PCA) is used for dimension reduction and data summary. However, principal components (PCs) cannot be easily interpreted. To interpret PCs, this study compares two methods to approximate PCs. One uses the PCA loadings to understand how input variables are projected to PCs. The other uses forward-stepwise regression to determine the proportions of PC variances explained by input variables.Methods:Two data sets derived from the Canadian Health Measures Survey (CHMS) were used to test the concept of PC approximation: a spirometry subset with the measures from the first trial of spirometry; and, full data set that contained representative variables. Variables were centered and scaled. PCA were conducted with 282 and twenty-three variables respectively. PCs were approximated with two methods.Results:The first PC (PC1) could explain 12.1 percent and 50.3 percent of total variances in respective data sets. The leading variables explained 89.6 percent and 79.0 percent of the variances of PC1 in respective data sets. It required one and two variables to explain more than 80 percent of the variances of PC1, respectively. Measures related to physical development were the leading variables to approximate PC1 and lung function variables were leading to approximate PC2 in the full data set. The leading variable to approximate PC1 of the spirometry subset were forced expiratory volume (FEV) 0.5/forced vital capacity (FVC) (percent) and FEV1/FVC (percent).Conclusions:Approximating PCs with input variables were highly feasible and helpful for the interpretation of PCs, especially for the first PCs. This method is also useful to identify major or unique sources of variances in data sets. The variables related to physical development are the variables related to the most variations in the full data set. The leading variable in the spirometry subset, FEV0.5/FVC (percent), is not well studied for its application in clinical use.

Comparison of diaphragmatic mobility between COPD patients with and without thoracic hyperkyphosis: a cross-sectional study.

ABSTRACTObjective:To compare diaphragmatic mobility, lung function, and respiratory muscle strength between COPD patients with and without thoracic hyperkyphosis; to determine the relationship of thoracic kyphosis angle with diaphragmatic mobility, lung function, and respiratory muscle strength in COPD patients; and to compare diaphragmatic mobility and thoracic kyphosis between male and female patients with COPD. Methods:Participants underwent anthropometry, spirometry, thoracic kyphosis measurement, and evaluation of diaphragmatic mobility. Results:A total of 34 patients with COPD participated in the study. Diaphragmatic mobility was significantly lower in the group of COPD patients with thoracic hyperkyphosis than in that of those without it (p = 0.002). There were no statistically significant differences between the two groups of COPD patients regarding lung function or respiratory muscle strength variables. There was a significant negative correlation between thoracic kyphosis angle and diaphragmatic mobility (r = −0.47; p = 0.005). In the sample as a whole, there were statistically significant differences between males and females regarding body weight (p = 0.011), height (p < 0.001), and thoracic kyphosis angle (p = 0.036); however, there were no significant differences in diaphragmatic mobility between males and females (p = 0.210). Conclusions:Diaphragmatic mobility is lower in COPD patients with thoracic hyperkyphosis than in those without it. There is a negative correlation between thoracic kyphosis angle and diaphragmatic mobility. In comparison with male patients with COPD, female patients with COPD have a significantly increased thoracic kyphosis angle.

Influence of Socio-Economic Status on Lung Function in Male Adolescents in Tanzania.

A lower socio-economic status (SES) associates with increased morbidity and mortality. The goal of this study was to define the influence of SES on lung function in indigenous male adolescents (aged 12.8-24.5years) in Tanzania. The subjects were subdivided into two age groups: <17.5 (n=189) and≥17.5years of age (n=101). They underwent anthropometric and spirometry evaluation. The SES was assessed on the basis of economic family resources and the subjects' nutritional status, and was stratified into three categories: SES-1 (low), SES-2 (average), and SES-3 (high). Relative contributions of body mass index, chest expansion/mobility, waist-to-chest ratio, and SES to spirometry variables were statistically determined. We found significant differences in forced expiratory volume in 1s (FEV1) and forced vital capacity (FVC) in the older, but not younger age group, by the SES category. The adolescents aged ≥17.5 in high-SES-3 category had FEV1 and FVC greater by 29.3% and 42.5%, respectively, than those in low-SES-1 category in the same age group. There also were differences between the two age groups. The mean FEV1 and FVC in adolescents of high-SES-3 category, aged ≥17.5, were higher by 65.3% and 82.2%, respectively, than those in the corresponding SES-3 in adolescents aged <17.5. In younger adolescents, lung function variables associated mostly with body build parameters, whereas in older adolescents with SES. The study revealed a significant dependence of lung function, and thus plausibly a greater resistance to diseases, on the socio-economic status. We conclude that the socio-economic status be taken into consideration in the assessment of lung function in epidemiological and public health programs, particularly in the context of the developing countries, to obtain the most reliable results.

Asthma and Obesity in Children Are Independently Associated with Airway Dysanapsis

An increase in the prevalence of overweight and asthma has been observed. Both conditions affect negatively lung function in adults and children. The aim of this study was to analyze the effect of overweight and asthma on lung function in children. We designed a case-control study of healthy and asthmatic subjects nested within an epidemiological asthma prevalence study in children between 8 and 16 years of age. The effect of asthma and overweight on lung function was assessed by impulse oscillometry and spirometry obtained at baseline and 10-15 min after salbutamol. 188 children were recruited, 114 (61%) were asthmatics and 72 (38%) were overweight or obese. Children with asthma and overweight had a higher FVC (+1.16 z scores, p < 0.001) and higher FEV1 (+0.79 z scores, p = 0.004) and lower FEV1/FVC (-0.54 z scores, p = 0.008) when compared to healthy controls. Compared to normal weight asthmatics, the overweight had higher FVC (+0.78 z scores, p = 0.005) and lower FEV1/FVC (-0.50 z scores, p = 0.007). In the multivariate analysis, overweight was associated with an increase of 0.71 and 0.44 z scores in FVC and FEV1, respectively, and a reduction in FEV1/FVC by 0.40 z scores (p < 0.01 for all). Overweight had no effect on maximal flows and airway resistance at baseline, and this was not modified by inhalation of a bronchodilator. Asthma was also associated with higher post-BD FVC (0.45 z scores, p = 0.012) and FEV1 (0.35 z scores, p = 0.034) but not with FEV1/FVC and FEF25-75%. Two-way analysis of variance did not detect any interaction between asthma and overweight on lung function variables before or after bronchodilator. Our results suggest that asthma and overweight are independently associated with airway dysanaptic growth in children which can be further scrutinized using impulse oscillometry. Overweight contributed more to the reduction in FEV1/FVC than asthma in children without increasing airway resistance. Spirometry specificity and sensitivity for obstructive diseases may be reduced in populations with high prevalence of overweight. Adding impedance oscillometry to spirometry improves our understanding of the ventilatory abnormalities in overweight children.

Impact of Nocturnal Noninvasive Ventilation on Pulmonary Rehabilitation in Patients with End-Stage Lung Disease Awaiting Lung Transplantation

Background: Pulmonary rehabilitation (PR) in patients awaiting lung transplantation is crucial to ensure a transplant benefit. However, PR in patients with end-stage lung disease treated with noninvasive ventilation (NIV) remains an area of uncertainty. Objectives: The aim of the study was to assess the potential benefit of PR in patients awaiting lung transplantation treated with NIV. Methods: Patients awaiting lung transplantation who underwent comprehensive inpatient PR from 1998 to 2015 were retrospectively analyzed. Success of PR was assessed by comparing admission and discharge. Multivariate regression models were applied to assess the impact of long-term nocturnal NIV on PR success. Results: In total, 1,044 patients were included in the analysis. Thereof, 296 patients (28%) were treated with NIV. PR in patients treated with NIV resulted in a significant increase in 6-min walk distance (6MWD; from 250 ± 117 to 309 ± 116 m; p < 0.0001) and in various items of the Short Form Health Survey (SF)-36 questionnaire. The increase in 6MWD was higher in patients treated with NIV than in patients without NIV (59 ± 63 vs. 48 ± 55 m; p = 0.003). Furthermore, improvements of various lung function variables were higher in patients with NIV. Finally, multivariate generalized regression analysis revealed that NIV therapy was associated with improvement of 6MWD (p = 0.023) while controlling for various baseline characteristics. Conclusions: PR in patients with end-stage lung disease awaiting lung transplantation on nocturnal NIV is feasible and is associated with improvements of exercise capacity and quality of life. Furthermore, despite more advanced lung disease, patients treated with NIV have an increased benefit of PR compared to patients without NIV while awaiting lung transplantation.

Effect of Rho-kinase inhibition on complexity of breathing pattern in a guinea pig model of asthma.

Asthma represents an episodic and fluctuating behavior characterized with decreased complexity of respiratory dynamics. Several evidence indicate that asthma severity or control is associated with alteration in variability of lung function. The pathophysiological basis of alteration in complexity of breathing pattern in asthma has remained poorly understood. Regarding the point that Rho-kinase is involved in pathophysiology of asthma, in present study we investigated the effect of Rho-kinase inhibition on complexity of respiratory dynamics in a guinea pig model of asthma. Male Dunkin Hartley guinea pigs were exposed to 12 series of inhalations with ovalbumin or saline. Animals were treated by the Rho-kinase inhibitor Y-27632 (1mM aerosols) prior to each allergen challenge. We recorded respiration of conscious animals using whole-body plethysmography. Exposure to ovalbumin induced lung inflammation, airway hyperresponsiveness and remodeling including goblet cell hyperplasia, increase in the thickness of airways smooth muscles and subepithelial collagen deposition. Complexity analysis of respiratory dynamics revealed a dramatic decrease in irregularity of respiratory rhythm representing less complexity in asthmatic guinea pigs. Inhibition of Rho-kinase reduced the airway remodeling and hyperreponsiveness, but had no significant effect on lung inflammation and complexity of respiratory dynamics in asthmatic animals. It seems that airway hyperresponsiveness and remodeling do not significantly affect the complexity of respiratory dynamics. Our results suggest that inflammation might be the probable cause of shift in the respiratory dynamics away from the normal fluctuation in asthma.