Relationship Between Functional Exercise Capacity and Lung Functions in Obese Chidren

Objective:Cardiovascular, respiratory and musculoskeletal system disorders which may affect the functional exercise capacity are common in obese patients. We aimed to investigate the functional exercise capacity and its relationship with functional pulmonary capacity in obese children.Methods:A total of 74 obese and 36 healthy children as a control group were enrolled in the study. Pulmonary functions and functional exercise capacity were measured by spirometry and six-minute walk test (6 MWT), respectively.Results:The distances covered during the 6 MWT in obese and control groups were 570.9±67.5 and 607.8±72.5 meters, respectively (p=0.010). In spirometric pulmonary function tests (PFTs), forced expiratory volume in 1 sec (FEV1) and forced mid-expiratory flows (25-75) were lower in the obese group (p=0.048 and p=0.047, respectively), whereas forced vital capacity (FVC), the FEV1/FVC ratio and peak expiratory flow were not statistically different between the obese and control groups. Multiple regression analysis revealed that among all parameters of anthropometric measures and PFTs, only body mass index standard deviation score (BMI-SDS) was the independent factor influencing 6 MWT.Conclusion:Functional exercise and lung capacities of obese children were diminished as compared to those of non-obese children. The most important factor influencing functional exercise capacity was BMI-SDS.     

Is it useful to perform carbon monoxide diffusion capacity and respiratory muscle function tests in patients with multiple sclerosis without disability?

Background and objective: Impairment of respiratory function has been described in end‐stage multiple sclerosis (MS), as well as in patients with mild to severe disability. No data are available regarding the respiratory function of MS patients without disability. The objective of this study was to assess the pulmonary function, respiratory muscle strength and carbon monoxide diffusion capacity of the lungs (DL_CO) in patients with relapsing‐remitting multiple sclerosis (RRMS) without disability. Methods: Twenty‐seven RRMS patients and 25 healthy control subjects were recruited. All subjects underwent clinical and neurological examination, and spirometry; lung volumes, DL_CO and maximal respiratory pressures were measured. All subjects were rated on the Modified Fatigue Impact Scale and Fatigue Severity Scale scales. Results: There were no significant differences in age, gender, height, weight or body mass index between the groups. The mean duration of illness in the MS group was 5.44 ± 3.74 years, and the mean Expanded Disability Status Scale was 0.62 ± 0.65. The mean values for total lung capacity, forced expiratory volume in 1 s (FEV₁) and FEV₁/FVC were normal in both groups. Fifteen RRMS patients exhibited a reduction in maximal expiratory pressure (MEP), but only one patient exhibited a reduction in maximal inspiratory pressure. The mean values for DL_CO were lower in RRMS patients (P = 0.0004) than in the control group. DL_CO was decreased in 15 (55.55%), out of 27 RRMS patients. The fatigue scale results were not correlated with pulmonary function test results Conclusions: DL_CO and MEP may be impaired in RRMS patients without disability.     

Recovery of pulmonary functions,exercise capacity,and quality of life after pulmonary rehabilitation in survivors of ARDS due to severe influenza A (H1N1) pneumonitis

Background

Acute respiratory distress syndrome (ARDS) due to severe influenza A H1N1 pneumonitis would result in impaired pulmonary functions and health‐related quality of life (HRQoL) after hospital discharge.

Objectives

The recovery of pulmonary functions, exercise capacity, and HRQoL in the survivors of ARDS due to 2009 pandemic influenza A H1N1 pneumonitis (H1N1‐ARDS) was evaluated in a tertiary teaching hospital in northern Taiwan between May 2010 and June 2011.

Patients and Methods

Data of spirometry, total lung capacity (TLC), diffusing capacity of carbon monoxide (DL_CO), and 6‐minute walk distance (6MWD) in the patients survived from H1N1‐ARDS were collected 1, 3, and 6 months post‐hospital discharge. HRQoL was evaluated with St. George respiratory questionnaire (SGRQ).

Results

Nine survivors of H1N1‐ARDS in the study period were included. All these patients received 2 months’ pulmonary rehabilitation program. Pulmonary functions and exercise capacity included TLC, forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), DL_CO, and 6MWD improved from 1 to 3 months post‐hospital discharge. Only TLC had further significant improvement from 3 to 6 months. HRQoL represented as the total score of SGRQ had no significant improvement in the first 3 months but improved significantly from 3 to 6 months post‐discharge.

Conclusion

The impaired pulmonary functions and exercise capacity in the survivors of H1N1‐ARDS improved soon at 3 months after hospital discharge. Their quality of life had keeping improved at 6 months even though there was no further improvement of their pulmonary functions and exercise capacity.     

Forced Oscillation Technique and Small Airway Involvement in Chronic Hypersensitivity Pneumonitis

ObjectiveHypersensitivity pneumonitis (HP) is an interstitial lung disease caused by the inhalation of specific organic antigens or low-molecular weight substances in genetically susceptible individuals. Although small airway involvement is prominent in patients with chronic HP, conventional pulmonary function tests (PFTs) are relatively insensitive to identify it. Thus, the authors aimed to evaluate resistance (R5) and reactance (X5) values at 5 Hz on inspiration, expiration, and whole breath, as well as small airway resistance (R_5–19) values using a forced oscillation technique (FOT) in patients with chronic HP, and their responses after bronchodilator. In addition, R5 and X5 values according to the presence or absence of mosaic attenuation on computed tomography (CT) were compared.MethodsPFTs with plethysmography, diffusing capacity of the lungs for carbon monoxide (DL_CO) and FOT measurements were performed pre-bronchodilator and post-bronchodilator. High-resolution CT was performed at the same visit, and classified according to the presence or absence of mosaic attenuation. R5 and X5 values were then compared according to the presence or absence of mosaic attenuation on CT.ResultsTwenty-eight patients with chronic HP (57.1% female; mean age, 56 ± 11.5 years; mean forced vital capacity 57 ± 17% predicted) were evaluated. All patients had low X5 values, reflecting lower lung compliance, and only three (8%) demonstrated elevated R5 (whole-breath) values. No patients exhibited bronchodilator response in R5, X5 and R_5–19 values. In patients who exhibited greater extension of mosaic attenuation (n = 11), R5 and X5 values could not discriminate those with a greater presence of these areas on CT.ConclusionsThe results suggest that FOT does not help to additionally characterise concomitant small airway involvement in patients with chronic fibrotic HP who demonstrate restrictive ventilatory pattern in conventional PFTs. Nevertheless, FOT appeared to better characterise decreased lung compliance due to fibrosis through X5. Bronchodilator therapy did not appear to induce an acute response in chronic HP patients with restrictive disease. The precise role of FOT in subacute HP and obstructive chronic HP, therefore, must be evaluated.     

Consumo máximo de oxígeno durante la prueba de marcha de 6 minutos en la enfermedad pulmonar intersticial difusa y en la hipertensión pulmonar

Introduction

The six-minute walk test (6MWT) is widely used in evaluating diffuse interstitial lung disease (ILD) and pulmonary hypertension (PH). However, their physiological determining factors have not been well defined.

Objective

To evaluate the physiological changes that occur in ILD and PH during the 6MWT, and compare them with the cardiopulmonary exercise test (CPET).

Material and methods

Thirteen patients with ILD and 14 with PH were studied using the 6MWT and CPET on an ergometer cycle. The respiratory variables were recorded by means of telemetry during the 6MWT.

Results

Oxygen consumption (VO₂), respiratory and heart rate reached a plateau from minute 3 of the 6MWT in both diseases. The VO₂ did not differ from the peak value in the CPET (14±2 and 15±2 ml/kg/min, respectively, in ILD; 16±6 and 16±6 ml/kg/min, in PH). The arterial oxygen saturation decreased in both diseases, although it was more marked in ILD (−12±5%, p<0,01). The ventilatory equivalent for CO₂ (V_E/VCO₂) in PH during the 6MWT was strongly associated with functional class (FC) (85±14 in FC III-IV, 44±6 in FC I-II; p<0,001).

Conclusions

The 6MWT in ILD and PH behaves like a maximal effort test, with similar VO₂ to the CPET, demonstrating a limit in oxygen transport capacity. Monitoring using telemetry during the 6MWT may be useful for the clinical evaluation of patients with ILD or PH.     

Oscillometric and spirometric bronchodilator response in preschool children with and without asthma

BACKGROUND:

Bronchodilator responses (BDR) are routinely used in the diagnosis and management of asthma; however, their acceptability and repeatability have not been evaluated using quality control criteria for preschool children.

OBJECTIVES:

To compare conventional spirometry with an impulse oscillometry system (IOS) in healthy and asthmatic preschool children.

METHODS:

Data from 30 asthmatic children and 29 controls (two to six years of age) who underwent IOS and spirometry before and after salbutamol administration were analyzed.

RESULTS:

Stable asthmatic subjects significantly differed versus controls in their spirometry-assessed BDR (forced expiratory volume in 1 s [FEV₁], forced vital capacity and forced expiratory flow at 25% to 75% of forced vital capacity) as well as their IOS-assessed BDR (respiratory resistance at 5 Hz [Rrs₅], respiratory reactance at 5 Hz and area under the reactance curve). However, comparisons based on the area under the ROC curve for ΔFEV₁ % initial versus ΔRrs₅ % initial were 0.82 (95% CI 0.71 to 0.93) and 0.75 (95% CI 0.62 to 0.87), respectively. Moreover, the sensitivity and specificity for ΔFEV₁ ≥9% were 0.53 and 0.93, respectively. Importantly, sensitivity increased to 0.63 when either ΔFEV₁ ≥9% or ΔRrs₅ ≥29% was considered as an additional criterion for the diagnosis of asthma.

CONCLUSION:

The accuracy of asthma diagnosis in preschool children may be increased by combining spirometry with IOS when measuring BDR.     

Handgrip strength measurement in patients with chronic obstructive pulmonary disease: Possible predictor of exercise capacity

BackgroundImpaired exercise capacity is one of the most important prognostic factors for patients with chronic obstructive pulmonary disease (COPD). The 6-min walk test (6MWT) is a widely used method for assessing exercise capacity in patients with COPD. However, the 6MWT requires considerable effort from patients. Therefore, a less physically demanding, but also noninvasive, method is warranted. The objective of this study was to determine the predictors of the 6MWT distance (6MWD) in patients with COPD.MethodsThis retrospective observational study enrolled 133 Japanese patients with COPD. All patients underwent the 6MWT, COPD assessment test (CAT), spirometry, respiratory muscle strength evaluation, body composition assessment, and handgrip strength (HGS) measurement. We examined the associations between the 6MWD and evaluated parameters.ResultsFrom single regression analysis, the 6MWD was significantly correlated with age, CAT score, several spirometric measurements (e.g., percentages of forced vital capacity, forced expiratory volume in 1 s, and carbon monoxide diffusing capacity of the lungs [%DLCO]), respiratory muscle strength parameters (e.g., percentages of maximal expiratory and inspiratory pressures), skeletal muscle mass index, and HGS. In multiple regression analysis, age, CAT score, %DLCO, and HGS were independent predictors of the 6MWD. The %DLCO and HGS were strongly correlated as predictors of the 6MWD (p < 0.001).ConclusionsWe found that HGS was significantly correlated with the 6MWD compared with spirometric measurements or respiratory muscle strength parameters in Japanese patients with COPD, suggesting that HGS could be a simple and noninvasive predictor of the 6MWD in patients with COPD.     

Spirometry and impulse oscillometry (IOS) for detection of respiratory abnormalities in metropolitan firefighters

Background and objective: As firefighters are at increased risk of adverse health effects, periodic examination of their respiratory health is important. The objective of this study was to establish whether the use of impulse oscillometry (IOS) reveals respiratory abnormalities in metropolitan firefighters that go undetected during routine respiratory health screening by spirometry and assessment of respiratory symptoms. Methods: This was a cross‐sectional analysis of spirometry, IOS and questionnaire data from 488 male firefighters. Abnormal spirometry was defined as FEV₁, FEV₁/FVC and/or FEF₅₀ below the lower limit of normal. Abnormal IOS was defined as resistance at 5 Hz (R5), frequency dependence of resistance (ΔR5‐R20) and/or reactance area (AX) above the upper limit of normal. Respiratory symptoms, smoking history, exposures and medical history were assessed. Data were analysed using logistic and linear regression models. Results: The mean age of the firefighters was 43.8 (SD 8.4) years. There were 123 (25%) former smokers and 50 (10%) current smokers. Abnormal spirometry was detected in 12%, abnormal IOS in 9% and respiratory symptoms in 20% of firefighters. Current smoking was associated with all IOS parameters (OR for R5 = 3.1, OR for ΔR5‐R20 = 7.7, OR for AX = 4.3), and with FEF₅₀ (OR = 9.1), chronic productive cough (OR = 4.0) and breathlessness (OR = 5.4) (P < 0.05 for all). Exposure during firefighting duties was associated with chronic productive cough (OR = 2.6), but not with spirometry or IOS parameters. Interaction terms in the linear regression models indicated associations between smoking and ΔR5‐R20, and also between smoking and AX, in the lowest and second lowest quartiles of spirometry parameters. Conclusions: Application of IOS for the assessment of respiratory health in firefighters identified airways dysfunction in some individuals, even when spirometry values were within the normal range and there were no respiratory symptoms.     

Functional capacity,lung function,and muscle strength in patients undergoing hematopoietic stem cell transplantation: A prospective cohort study

Objective/BackgroundHematopoietic stem cell transplantation (HSCT) is a treatment for benign and malignant hematological diseases. These aggressive treatments cause reduced levels of physical activity, decreased lung function, and worse quality of life. Alterations in pulmonary function tests before HSCT are associated with the risk of respiratory failure and early mortality. The objective of this study was to evaluate functional capacity and lung function before and after HSCT and identify the predictors of mortality after 2 years.MethodsA prospective cohort study was carried out with individuals with oncohematological diseases. The evaluations were carried out in two moments during hospitalization and at hospital discharge. Follow-up was carried out after 48 months. Assessments were carried out on 34 adults, using spirometry, manovacuometry, 6-Minute Walk Test (6MWT), Handgrip Strength Test, and 30-Second Chair Stand Test (30-s CST).ResultsThere was a statistically significant reduction for the variables in forced vital capacity, forced expiratory volume predicted in the 1st second, Tiffeneau index, handgrip strength, and distance covered (% predicted) on the 6MWT (p < .05). There was a significant difference in the 30-s CST when individuals were compared according to the type of transplant. We found that a 10% reduction in the values of maximum inspiratory pressure (MIP) can predict an increased risk for mortality.ConclusionsIndividuals undergoing HSCT have reduced functional capacity, lung function, and muscle strength during the hospitalization phase. Reduction in the values of MIP increases the risk of nonrelapse mortality.     

Pulmonary Artery Abnormalities in Ex-smokers with and without Airflow Obstruction

Pulmonary vascular disease is a common complication of chronic obstructive pulmonary disease (COPD), and an important risk factor for COPD exacerbations and death. We explored the relationship between pulmonary artery volumes measured using thoracic computed tomography (CT) and lung structure-function measured using spirometry, CT and magnetic resonance imaging (MRI) in 124 ex-smokers with (n = 68) and without (n = 56) airflow obstruction, and a control group of 35 never-smokers. We observed significantly greater main (p = .01), right (p = .001) and total (p = .003) pulmonary artery volumes in ex-smokers with airflow obstruction as compared to ex-smokers without airflow obstruction. There were also significantly greater pulmonary artery volumes in both ex-smoker subgroups, compared to the never-smoker subgroup (p = .008). For all participants, there were significant correlations for pulmonary artery volumes with the ratio of the forced expiratory volume in 1 s to forced vital capacity (FEV₁/FVC), the diffusing capacity of the lung for carbon monoxide (DL_CO%_pred), airway count, MRI ventilation defect percent and MRI apparent diffusion coefficients. In ex-smokers, ventilation defect percent was significantly correlated with right (r = 0.27, p = .02) and total (r = 0.25, p = .03) pulmonary artery volumes. Multivariate zero-inflated Poisson regression analysis showed that FEV₁%_pred (p = .004), DL_CO%_pred (p = .03), the six minute walk distance (p = .04) and total pulmonary artery volume (p = .03) were significant predictors of acute exacerbations of COPD, while the number of previous exacerbations was not. In conclusion, pulmonary artery enlargement measured using thoracic CT was observed even in ex-smokers without airflow obstruction and was predictive of COPD exacerbations in ex-smokers with airflow obstruction.     

Rationale and design of the Early Chronic Obstructive Pulmonary Disease (ECOPD) study in Guangdong,China: a prospective observational cohort study

BackgroundChronic obstructive pulmonary disease (COPD) is a heterogeneous disease and its clinically relevant subtypes are not well understood. Which clinical characteristics are more likely to be present among individuals who develop COPD remains to be studied in depth. Therefore, we designed a prospective observational cohort study, entitled the Early Chronic Obstructive Pulmonary Disease (ECOPD) study, to fill this evidence gap. The ECOPD study has four specific aims: (I) identification of characteristics, parameters, and biomarkers that may predict the development of airflow obstruction and annual decline in lung function with normal spirometry; (II) identification of clinically relevant early COPD subtypes; (III) identification of characteristics, parameters, and biomarkers that may predict disease progression in these early COPD subtypes; (IV) development and validation of machine learning models to predict development of airflow obstruction and disease progression.MethodsWe will recruit approximately 2,000 participants aged 40–80 years, including approximately 1,000 with COPD [post-bronchodilator forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) <0.7] and approximately 1,000 without COPD, using a population-based survey for COPD. We will assess all participants using standard respiratory epidemiological questionnaires, pulmonary function tests [pre-bronchodilator and post-bronchodilator spirometry, and impulse oscillometry (IOS)], health outcomes [modified British Medical Research Council (mMRC) dyspnea scale, COPD assessment test (CAT), COPD clinical questionnaire (CCQ)], inspiratory and expiratory chest computed tomography (CT), and biomarker measurements (blood and urine), as well as satellite remote sensing pollutant exposure measures. Subgroup will additionally complete induced sputum, exercise capacity tests [6-minute walk test (6MWT) and cardiopulmonary exercise testing (CPET)] and home monitoring/personal sampling as pollutant exposure measures. Study procedures will be performed at baseline and every 1 year thereafter.DiscussionThe ECOPD study will provide insight into many aspects of early COPD and improve our understanding of COPD development, which may facilitate therapeutic interventions with the potential to modify the course of disease.Trial RegistrationChinese Clinical Trial Registry, ChiCTR1900024643. Registered on 19 July, 2019.     

The role of impulse oscillometry in detecting airway dysfunction in athletes

Background: Impulse oscillometry (IOS) has previously been proposed to provide greater sensitivity than spirometry when employed with indirect bronchoprovocation testing for the diagnosis of airway dysfunction in athletes. However, this recommendation is based on a highly selected population of symptomatic patients. Objective: To compare IOS, spirometry and respiratory symptoms following indirect bronchoprovocation in a screened cohort of athletes. Methods: One hundred and one recreational athletes were recruited. Respiratory symptoms were assessed via the Dyspnoea-12 questionnaire. Spirometry and IOS were performed pre and post a eucapnic voluntary hyperpnoea (EVH) challenge. Results: Ninety-four athletes completed the study. Sixteen athletes (17%) were positive for airway dysfunction based on spirometry (i.e. ≥10% fall in FEV₁) and 17 athletes (18%) based on IOS (i.e. ≥50% increase in R₅). Only nine athletes (10%) met both diagnostic thresholds. A poor relationship was observed between respiratory symptoms (i.e. Dyspnoea-12 score) and all spirometry and IOS variables. A direct relationship was observed between percentage change in R₅ (r?=?0.65), Z₅ (r?=?0.68), R_F (r?=?0.65), A_X (r?=?0.69) and the maximum fall in FEV₁ (ΔFEV₁max; p?<?0.001). A weak relationship was observed between R₂₀ (r?=?0.27), X₅ (r?=?0.37) and ΔFEV₁max (p?<?0.01). Conclusion: Impulse oscillometry and spirometry do not concur precisely following indirect bronchoprovocation. However, IOS detects additional cases of airway dysfunction in athletes and therefore may provide diagnostic value in this population. Further work is required to establish diagnostic thresholds and fully determine the place of IOS in screening athletes for airway dysfunction.     

Exhaled nitric oxide as a better diagnostic indicator for evaluating wheeze and airway hyperresponsiveness in preschool children

Objective: Fractional concentration of exhaled nitric oxide (FeNO) is a known marker of airway inflammation. The aims of this study were to evaluate FeNO, impulse oscillometry (IOS), and spirometry in preschool children and to investigate their relationship with wheeze and airway hyperresponsiveness (AHR). Methods: We performed a population-based, cross-sectional study with 561 children aged 5–6 years. A total of 544 children completed a modified International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and eligible for the study. We measured FeNO, spirometry, methacholine bronchial provocation, and IOS. AHR was defined as the induction of a 20% decrease in FEV₁(PC₂₀) by a methacholine concentration ≤8.0?mg/dL. Results: Children who had wheeze or AHR had higher FeNO levels than children without these symptoms. However, neither IOS nor spirometry parameters showed significant differences between children with wheeze or AHR and those without. FeNO was associated with AHR, whereas IOS or spirometry parameters showed no association. Mean FeNO levels were positively correlated with a dose–response slope for methacholine, but neither IOS nor spirometry parameters showed significant correlations. Conclusions: FeNO is a more sensitive measurement of AHR and wheeze than spirometry or IOS in preschool children.     

Effect of bronchodilatation on single breath pulmonary uptake of carbon monoxide in chronic obstructive pulmonary disease

We studied 21 COPD patients in stable clinical conditions to evaluate whether changes in lung function induced by cumulative doses of salbutamol alter diffusing capacity for carbon monoxide (DL_CO), and whether this relates to the extent of emphysema as assessed by high resolution computed tomography (HRCT) quantitative analysis. Spirometry and DL_CO were measured before and after cumulative doses of inhaled salbutamol (from 200 μg to 1000 μg). Salbutamol caused significant increments of forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and flows at 30% of control FVC taken from both partial and maximal forced expiratory maneuvers. Functional residual capacity and residual volume were reduced, while total lung capacity did not change significantly. DL_CO increased progressively with the incremental doses of salbutamol, but this became significant only at the highest dose (1000 μg) and was independent of the extent of emphysema, as assessed by radiological parameters. No significant changes were observed in CO transfer factor (DLCO/VA) and alveolar volume (VA). The results suggest that changes in lung function induced by cumulative doses of inhaled salbutamol are associated with a slight but significant increase in DL_CO irrespective of the presence and extent of emphysema.     

Diffusing capacity for carbon monoxide in children with type 1 diabetes

Aims/hypothesis Few data are available on lung dysfunction in children with diabetes. We studied the association of pulmonary function variables (flows, volumes and alveolar capillary diffusion) with disease-related variables in children with type 1 diabetes mellitus.Methods We studied 39 children with type 1 diabetes (mean age 10.9±2.6 years, disease duration 3.6±2.4 years, insulin·kg^–1·day^–1 0.77±0.31) and 30 healthy control children (mean age 10.4±3.0 years). Pulmonary function tests included spirometry, N₂ wash-out and the single-breath diffusing capacity for carbon monoxide (DL_CO) corrected for the alveolar volume (DL_CO/V_A). Glycaemic control was assessed on the basis of HbA₁c, with HbA₁c values of 8% or less considered to indicate good glycaemic control, and HbA₁c values of 8% or more considered to indicate poor control.Results Children with poor glycaemic control had comparable percentage values for predicted flows and volumes but lower DL_CO/V_A values than children with good glycaemic control and healthy control children (86.7±12.6 vs 99.8±18.4 and 102.0±15.7; p<0.05). The predicted DL_CO/V_A percentages correlated with HbA₁c levels (r=–0.39, p=0.013). A multiple regression analysis (stepwise model) controlling for HbA₁c levels and other disease-related variables (age of disease onset, disease duration, daily insulin dose/kg, sex) identified HbA₁c levels as the sole predictor of DL_CO/V_A in percent.Conclusions/interpretation In children with type 1 diabetes, the diffusing capacity diminishes early in childhood and is associated with poor metabolic control. Although low DL_CO/V_A levels in these children probably reflect pulmonary microangiopathy induced by type 1 diabetes, other factors presumably influencing CO diffusion capacity measurements (e.g. a left shift in HbA₁c resulting in high O₂ binding and low CO binding) could explain the apparent capillary and alveolar basal membrane dysfunction.     

Difference Between Slow and Forced Vital Capacity and Its Relationship with Dynamic Hyperinflation in Patients with Chronic Obstructive Pulmonary Disease

The aim of the study was to investigate the relationship between slow and forced vital capacity (SVC–FVC) difference with dynamic lung hyperinflation (DH) during the 6-min walking test (6MWT) in subjects with chronic obstructive pulmonary disease (COPD). Twenty-four subjects with COPD (12 males; 67 ± 6 years; forced expiratory volume in first second [FEV₁] 56 ± 18% predicted) performed lung function tests by spirometry and plethysmography. DH was assessed by serial measurements of inspiratory capacity (IC) performed during the 6MWT and defined as ∆IC ≥ 150 mL or 10%. IC decrease significantly during the 6MWT (ΔCI: − 0.48 ± − 0.40 L; P < 0.0001), and 18 individuals (75%) presented DH. There was significant difference when comparing IC measured at rest with the other serial IC measurements (P < 0.0001). Correlation between the SVC–FVC difference and DH during the 6MWT was r = − 0.38; P = 0.06. The SVC–FVC difference presented only weak correlation with the development of DH during the 6MWT in patients with COPD.

     

Impulse oscillometry in acute and stable asthmatic children: a comparison with spirometry

Objective: Lung function tests have attracted interest for the diagnosis and follow-up of childhood asthma in recent years. For patients who cannot perform forced expiratory maneuvers, impulse oscillometry (IOS), performed during spontaneous breathing, may be an alternative tool. Methods: Thirty-five acute, 107 stable asthmatic and 103 healthy children who presented to our clinic performed IOS followed by spirometry before and after salbutamol inhalation. The mean baseline and reversibility of IOS and spirometry parameters were compared between the groups. Correlation analyses were undertaken within the asthmatics, and the healthy controls separately. To distinguish the three groups, the sensitivity and specificity of baseline and reversibility values of IOS and spirometry were computed. When spirometry was taken as the gold standard, the discriminating performance of IOS to detect the airway obstruction and reversibility was investigated. Results: The mean absolute values of Zrs, R5, R5?R20, X5, X10, X15, Fres, AX, and all spirometric parameters, and the mean reversibility values of R5, R10, Fres, AX and forced expiratory volume in one second were different between the groups and the highest area under curve values to discriminate the groups was obtained from area of reactance (AX) and ΔAX. Zrs, all resistance (including R5?R20) and reactance parameters, Fres and AX were correlated with at least one spirometric parameter. Spirometric reversibility was detected by ≤?22.34 and ≤?39.05 cut-off values of ΔR5 and ΔAX, respectively. Conclusions: IOS has shown a highly significant association with spirometric indices and reversibility testing. It may be a substitute for spirometry in children who fail to perform forced expiratory maneuvers.     

Different COPD Disease Characteristics are Related to Different Outcomes in the 6-minute Walk Test

Abstract

Background: Chronic obstructive pulmonary disease (COPD) can lead to severe disability as the disease advances. The 6-minute walk test (6MWT) is commonly used to measure functional capacity in COPD patients and has three potential outcomes; walking distance, oxygen desaturation, and self-perceived dyspnea assessed by the Borg scale, all reflecting different aspects of COPD. The aim of this study was to identify predictors of all 3 outcomes of 6MWT in patients with COPD. Methods: 370 COPD patients, aged 40–75 yrs, were included from the first phase of the Bergen COPD cohort study. They were examined with spirometry, bioelectrical impedance measurements, 6MWT, Center for Epidemiologic Studies of Depression (CES-D) Scale, Medical Research Council (MRC) dyspnea scale, Charlson index for co-morbidities, self-reported physical activity questionnaire, plasma levels of C-reactive protein (CRP) and arterial blood gases. Results: Significant predictors in the multivariate analyses were sex, age, FEV₁ in% predicted, symptoms of dyspnea (MRC), co-morbidities (Charlson Index) and self-reported physical activity for walking distance, FEV₁ in% predicted and PaO₂ for oxygen desaturation, and body composition, smoking and co-morbidities for self-perceived dyspnea assessed by the Borg scale. Conclusion: Several COPD characteristics have predictive value for the 6MWT, and some COPD characteristics are more strongly related to specific 6MWT outcomes than others.     

Abnormal pulmonary function and imaging studies in critical COVID-19 survivors at 100 days after the onset of symptoms

BackgroundThe long-term repercussions of critical COVID-19 on pulmonary function and imaging studies remains unexplored. In this study, we investigated the pulmonary function and computed tomography (CT) findings of critical COVID-19 patients approximately 100 days after symptom onset.MethodsWe retrospectively extracted data on critical COVID-19 patients who received invasive mechanical ventilation during hospitalization from April to December 2020 and evaluated their pulmonary function, residual respiratory symptoms and radiographic abnormalities on CT.ResultsWe extracted 17 patients whose median age was 63 (interquartile range [IQR], 59–67) years. The median lengths of hospitalization and mechanical ventilation were 23 (IQR, 18–38) and 9 (IQR, 6–13) days, respectively. At 100 days after symptom onset, the following pulmonary function abnormalities were noted in 8 (47%) patients: a diffusion capacity of the lung for carbon monoxide (%DL_CO) of <80% for 6 patients (35%); a percent vital capacity (%VC) of <80% for 4 patients (24%); and a forced expiratory volume in one second/forced vital capacity (FEV₁%) of <70% for 1 patient (6%) who also presented with %DL_CO and %VC abnormalities. Twelve (71%) patients reported residual respiratory symptoms and 16 (94%) showed abnormalities on CT.ConclusionsOver 90% of the critical COVID-19 patients who underwent invasive mechanical ventilation continued presenting with abnormal imaging studies and 47% of the patients presented with abnormal pulmonary function 100 days after symptom onset. The extent of the residual CT findings might be associated with the degree of abnormal pulmonary function in critical COVID-19 survivors.     

Exertional hypoxemia is more severe in fibrotic interstitial lung disease than in COPD

Background and objective

Despite its clinical and prognostic significance, few studies have evaluated the severity of exertional oxygen desaturation in fibrotic interstitial lung disease (ILD). Our objectives were to identify clinical and physiological variables that predict the extent of exertional oxygen desaturation in fibrotic ILD and to quantify the severity of desaturation compared to chronic obstructive pulmonary disease (COPD).

Methods

This retrospective study compared the results of 6‐min walk test (6MWT) performed while breathing room air in fibrotic ILD patients and COPD patients eligible for pulmonary rehabilitation. Outcomes included the oxygen saturation (SpO₂) nadir and the change in SpO₂ from rest during a 6MWT. Predictor variables were identified on unadjusted analysis, followed by multivariate analysis to identify independent predictors of desaturation.

Results

The study included 134 patients with fibrotic ILD and 274 patients with COPD. The ILD and COPD cohorts had similar age, sex, frequency of major comorbidities, walk distance, baseline SpO₂ and baseline Borg dyspnoea scores. DL_CO was the strongest predictor of desaturation in both cohorts. Compared to patients with COPD, ILD patients had significantly lower SpO₂ nadir values (88.1 ± 6.4 vs 91.0 ± 4.6) and greater decrease in SpO₂ from baseline (7.4 ± 5.2 vs 4.5 ± 3.7) after adjusting for demographic features and pulmonary physiology (P < 0.0005), with greater between‐group differences at lower DL_CO values.

Conclusion

Patients with fibrotic ILD have greater oxygen desaturation during 6MWT compared to patients with COPD when adjusting for demographic features and pulmonary physiology. These findings suggest the need for disease‐specific studies to evaluate the potential utility of ambulatory oxygen in fibrotic ILD.