Standardisation of the measurement of lung volumes

Molecular mechanisms of inflammation in the pathogenesis of respiratory disorders in patients with pulmonary tuberculosis

Aim. To assess external respiration (ER) and its relationship with the activity of enzymes involved in purine metabolism in patients with acute and chronic forms of pulmonary tuberculosis (TB).

Materials and methods. In patients with acute and chronic TB, we assessed the activity of adenosine deaminase (ADA)-1, 2 in the blood serum (eADA), mononuclear cells, and neutrophils, the concentration of ecto-5’-nucleotidase (eNT5E) in the blood serum, the level of CD26 (dipeptidyl peptidase-4, DPPIV) in the blood serum and mononuclear cells, production of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI) in mononuclear cells and neutrophils, as well as parameters of ER.

Results. Patients with TB were found to have an increase in the concentration of eNT5E and eADA-2 activity in the blood serum, stimulated production of ROI in neutrophils, a decrease in the concentration of DPPIV (CD26) in mononuclear cells, and a fall in the production of RNI in mononuclear cells and neutrophils. In patients with chronic TB, a decrease in the activity of ADA-1 in mononuclear cells and a fall in the concentration of DPPIV (CD26) in the blood serum were noted. In patients with acute TB, a decrease in the activity of eADA-1 in the blood serum and ADA-1 in neutrophils, reduced production of ROI in mononuclear cells, and an increase in spontaneous production of ROI in neutrophils were revealed. Correlations were found between the parameters of ER and the concentration of eNT5E in the blood serum, spontaneous production of ROI in mononuclear cells and production of RNI in neutrophils in chronic TB, as well as between eADA-2 in the blood serum, ADA-1 in neutrophils, DPPIV (CD26) activity in mononuclear cells, and ROI and RNI production in mononuclear cells and neutrophils.

Conclusion. The data obtained make it possible to associate regulation of external respiration with parameters of purine metabolism, in particular with the concentration and activity of enzymes responsible for generation and metabolism of adenosine, that determine its level outside cells and inside mononuclear cells and neutrophils, with expression of cofactor molecules, as well as with the duration of activation of cells in innate immunity, neutrophils, and monocytes/ macrophages, determined largely by the potential of adenosine regulation.

Critical functional lung volumes in neonatal intensive care: evidence and clinical applications

Respiratory disease is common in premature and sick newborn infants and can often necessitate the initiation of intensive care. Newborn infants often suffer from conditions that are associated with decreased lung volumes that occur as a result of abnormal or incomplete lung development. Such conditions are prematurity and respiratory distress syndrome, preterm premature rupture of membranes and the ensuing pulmonary hypoplasia and congenital lung anomalies such as congenital diaphragmatic hernia. These diseases have a structural component manifesting with lower lung volumes and a functional component that can present with increased oxygen and ventilatory requirements. The corresponding decreased functional lung volume is possibly responsible for some unfavourable pulmonary outcomes. Some infants are unable to wean off invasive respiratory support and, in extreme cases, unable to sustain independent breathing that can lead to long-term invasive ventilation or subsequent death. The aim of this review is to summarise the available evidence behind the concept of a critical functional lung volume in neonatal intensive care and describe the clinical implications that arise from decreased functional lung volumes in the main high-risk populations of newborn infants. IMPACT: Newborn infants suffer from diseases such as respiratory distress syndrome, pulmonary hypoplasia and congenital diaphragmatic hernia that are associated with a decrease in the total lung volume and impaired lung function. Critically decreased functional lung volumes during neonatal care are associated with failure to wean off invasive respiratory support, increased mortality and possibly longer-term respiratory complications.

Surfactant Protein B Plasma Levels: Reliability as a Biomarker in COPD Patients

Background: The diagnosis of COPD is based on both clinical signs and functional tests. Although there are different functional tests used to assess COPD, no reliable biomarkers able to provide information on pathogenesis and severity are available. The aim of the present study is to explore the relationship between surfactant protein B (Sp-B) serum levels and clinical, radiological, and functional pulmonary parameters in COPD patients. Methods: Forty COPD patients and twenty smokers without airflow limitations or respiratory symptoms were enrolled. Each patient was given questionnaires (CAT and mMRC) and 6MWT, spirometry, DLCO, and computer tomography (CT) were performed. All participants underwent a venous blood sample drawing, and quantitative detection of their Sp-B plasma levels was performed by an enzyme-linked immunosorbent assay. The spirometry and Sp-B plasma levels were assessed after 12 months. Results: A statistically significant difference was found in the plasma Sp-B levels between COPD patients compared to the other group (4.72 + 3.2 ng/mL vs. 1.78 + 1.5 ng/mL; p < 0.001). The change in FEV1 after 12 months (Delta FEV1) showed a significantly negative correlation with respect to the change in Sp-B levels (Delta SpB) (r = −0.4; p < 0.05). This correlation indicates that increasing the plasma dosage of SpB is a foretoken of functional decline. Conclusions: SpB may be considered as a useful marker in COPD assessment and provides prognostic information on lung functional decline. Despite its usefulness, further studies are needed to define its reliability as a biomarker.

Understanding the Impact of Pulmonary Rehabilitation on Airway Resistance in Patients with Severe COPD: A Single-Center Retrospective Study

Purpose

We investigated the effect of pulmonary rehabilitation (PR) on airway resistance in chronic obstructive pulmonary disease (COPD) patients with severe airway obstruction and hyperinflation.

Patients and Methods

This retrospective cohort study was conducted with data from severe COPD cases with those who underwent an 8-week PR program. Main inclusion criteria were having severe airflow obstruction (defined as a forced expiratory volume in one second (FEV₁) <50%) and plethysmographic evaluation findings being compatible with hyperinflation supporting the diagnosis of emphysema (presence of hyperinflation defined as functional residual capacity ratio of residual volume to total lung capacity (RV/TLC) >120%). Primary outcomes were airway resistance (R_aw) and airway conductance (G_aw) which were measured by body plethysmography, and other measurements were performed, including 6-minute walk test (6-MWT), modified Medical Research Council dyspnea scale (mMRC) and COPD assessment test (CAT).

Results

Twenty-six severe and very severe COPD patients (FEV_1, 35.0 ± 13.1%; RV/TLC, 163.5 ± 29.4) were included in the analyses, mean age 62.6 ± 5.8 years and 88.5% males. Following rehabilitation, significant improvements in total specific airway resistance percentage (sR_awtot%, p = 0.040) and total specific airway conductance percentage (sG_awtot%; p = 0.010) were observed. The post-rehabilitation mMRC scores and CAT values were significantly decreased compared to baseline results (p < 0.001 and p < 0.001, respectively). Although there were significant improvements in 6-MWT value (p < 0.001), exercise desaturation (ΔSaO₂, p = 0.026), the changes in measured lung capacity and volume values were not significant.

Conclusion

We concluded that PR may have a positive effect on airway resistance and airway conductance in COPD patients with severe airflow obstruction.

Cystic fibrosis related diabetes is not associated with maximal aerobic exercise capacity in cystic fibrosis: a cross-sectional analysis of an international multicenter trial

BACKGROUND

Previous studies have reported differences in aerobic exercise capacity, expressed as peak oxygen uptake (VO_2peak), between people with and without cystic fibrosis (CF) related diabetes (CFRD). However, none of the studies controlled for the potential influence of physical activity on VO_2peak. We investigated associations between CFRD and VO_2peak following rigorous control for confounders including objectively measured physical activity.

METHODS

Baseline data from the international multicenter trial ACTIVATE-CF with participants ≥12 years performing up to 4 h per week of vigorous physical activity were used for this project. Multivariable models were computed to study associations between CFRD and VO_2peak (mL.min^-1) adjusting for a set of pre-defined covariates: age, sex, weight, forced expiratory volume in 1 s (FEV₁), breathing reserve index, Pseudomonas aeruginosa infection, and physical activity (aerobic step counts from pedometry). Variables were selected based on their potential confounding effect on the association between VO_2peak and CFRD.

RESULTS

Among 117 randomized individuals, 103 (52% female) had a maximal exercise test and were included in the analysis. Participants with (n = 19) and without (n = 84) CFRD did not differ in FEV₁, physical activity, nutritional status, and other clinical characteristics. There were also no differences in VO_2peak (mL.min^-1 or mL.kg^-1.min^-1 or% predicted). In the final multivariable model, all pre-defined covariates were significant predictors of VO_2peak (mL.min^-1), however CFRD [coefficient 82.1, 95% CI -69.5 to 233.8, p = 0.28] was not.

CONCLUSIONS

This study suggests no meaningful differences in VO_2peak between people with and without CFRD given comparable levels of physical activity.

Pulmonary function in children with persistent tachypnea of infancy

BACKGROUND

Data on the prevalence and type of lung function impairment in preschool and school-aged children previously diagnosed with persistent tachypnea of infancy (PTI) are scarce. Therefore, this study aims to assess pulmonary function in this age group.

METHODS

Children diagnosed with PTI over 3 years old were admitted for follow-up visits and healthy controls were enrolled. The study group included children who were able to complete pulmonary function tests (PFTs). Medical history, physical examination, and pulmonary function (spirometry, body plethysmography, impulse oscillometry, nitrogen multiple breath washout test, diffusing capacity for carbon monoxide [DL_CO ]) were assessed.

RESULTS

Thirty-seven children (26 boys, 11 girls; median age: 5.6 years) diagnosed with PTI and 37 healthy controls were recruited. Forced expiratory volume in 1 s and forced vital capacity were significantly lower (-1.12 vs. 0.48, p = 0.002 and -0.83 vs. 0.31, p = 0.009, respectively); respiratory resistance at 5 Hz (0.06 vs. -0.62, p = 0.003), resonant frequency (1.86 vs. 1.36, p = 0.04), residual volume (RV) (2.34 vs. -1.2, p < 0.0001), RV%TLC (total lung capacity) (2.63 vs. -0.72, p < 0.0001), and specific airway resistance (5.4 vs. 2.59, p = 0.04) were significantly higher in PTI patients as compared with controls (data were presented as median z-score). Air trapping was found in 60.0%, and abnormally high lung clearance index and DL_CO  were found in 73.3% and 90.9% of PTI patients, respectively.

CONCLUSIONS

This study demonstrated that lung function is affected in most children with PTI. PFTs showed that peripheral airways are the major zone of functional impairment.

Voluntary activation of the diaphragm after inspiratory pressure threshold loading

After a bout of isolated inspiratory work, such as inspiratory pressure threshold loading (IPTL), the human diaphragm can exhibit a reversible loss in contractile function, as evidenced by a decrease in transdiaphragmatic twitch pressure (PDI,TW ). Whether or not diaphragm fatigability after IPTL is affected by neural mechanisms, measured through voluntary activation of the diaphragm (D-VA) in addition to contractile mechanisms, is unknown. It is also unknown if changes in D-VA are similar between sexes given observed differences in diaphragm fatigability between males and females. We sought to determine whether D-VA decreases after IPTL and whether this was different between sexes. Healthy females (n = 11) and males (n = 10) completed an IPTL task with an inspired duty cycle of 0.7 and targeting an intensity of 60% maximal transdiaphragmatic pressure until task failure. PDI,TW and D-VA were measured using cervical magnetic stimulation of the phrenic nerves in combination with maximal inspiratory pressure maneuvers. At task failure, PDI,TW decreased to a lesser degree in females vs. males (87 ± 15 vs. 73 ± 12% baseline, respectively, p = 0.016). D-VA decreased after IPTL but was not different between females and males (91 ± 8 vs. 88 ± 10% baseline, respectively, p = 0.432). When all participants were pooled together, the decrease in PDI,TW correlated with both the total cumulative diaphragm pressure generation (R2  = 0.43; p = 0.021) and the time to task failure (TTF, R2 = 0.40; p = 0.30) whereas the decrease in D-VA correlated only with TTF (R2  = 0.24; p = 0.041). Our results suggest that neural mechanisms can contribute to diaphragm fatigability, and this contribution is similar between females and males following IPTL.

Physical activity and liver disease affect the fat-free mass in adolescents with cystic fibrosis

Cystic fibrosis (CF) is predominantly a lung disease but is also characterised by impaired skeletal muscularity and a reduction in fat-free mass. We aimed to test the hypothesis that clinical and anthropometric parameters would determine fat-free mass impairment in adolescents with CF. We measured the fat-free mass index (FFMI) using bioelectrical impedance, the lung function using spirometry, the number of shuttles as a measure of exercise tolerance and the reported physical activity in children and young people with CF in a tertiary centre at King's College Hospital, London, UK. CF-related liver disease was diagnosed by abnormal liver enzymes and/or ultrasonography. We studied 28 children and young people (11 male) with a median (interquartile range (IQR)) age of 15 (13-17) years. They had a median (IQR) FFMI of 13.5 (11.6-15.1) kg/m². The FFMI significantly correlated with age (rho = 0.568, p = 0.002), number of shuttles (rho = 0.691, p < 0.001) and reported hours of activity per day (rho = 0.426, p = 0.024). The median (IQR) FFMI was significantly higher in male [15.1 (13.1-18.6) kg/m²] compared to female participants [12.7 (11.6-14.1) kg/m², p = 0.008]. The median (IQR) FFMI was significantly lower in the 10 (36%) participants with liver disease [11.9 (11.5-13.4) kg/m²] compared to the FFMI in the remaining 18 participants without liver disease [14.4 (12.5-15.9) kg/m², p = 0.027].

CONCLUSION

Fat-free mass increases with increasing age and growth in adolescents with CF. Physical activity exerts a beneficial effect on fat-free mass, and CF-related liver disease negatively affects fat-free mass in adolescents with CF.

WHAT IS KNOWN

• Health behaviours in adolescence influence lifelong health in cystic fibrosis (CF). • A normal body mass index in CF might fail to reveal a low fat-free mass (FFM), and quality of life in CF is strongly associated with a reduced FFM.

WHAT IS NEW

• FFM increases with increasing age and growth in adolescents with CF. • Physical activity exerts a beneficial effect, and liver disease negatively affects FFM in adolescents with CF.

Fidelity and tolerability of two high-intensity interval training protocols in patients with COPD: a randomised cross-over pilot study

Objectives

High-intensity interval training (HIIT) during pulmonary rehabilitation in patients with chronic obstructive pulmonary disease (COPD) may alleviate the symptom burden, but the fidelity and tolerability of HIIT using long or short intervals in patients with COPD are unknown.

Methods

Twelve patients with moderate-to-severe COPD were included in a randomised cross-over pilot study. They completed two supervised HIIT protocols (4×4 and 10×1). To compare the two HIIT protocols, completed training amount, exercise intensity and perceived tolerability (assessed by a 10-point Likert scale) were integrated in a red-amber-green rating system. If a training session received a red ranking, it was considered unacceptable, if it received an amber ranking it was applicable with precautions, and if it received a green ranking it was considered feasible.

Results

All patients completed the total training amount in both protocols. The 4×4 protocol resulted in three amber training sessions due to low perceived tolerability. The 10×1 protocol resulted in two red training sessions due to intensity reductions, and two amber training sessions because of low perceived tolerability. There was no statistical difference in perceived tolerability or time spent with an HR ≥85% of HR_max.

Conclusions

HIIT using longer intervals (4×4) at a relatively lower intensity resulted in higher fidelity expressed by fewer adjustments to the protocol, whereas there was no difference between protocols in perceived tolerance. The 4×4 protocol seems to have a higher fidelity compared with the 10×1 protocol in patients with moderate-to-severe COPD.

Trial registration number

NCT05273684.

Fibrosis score predicts mortality in patients with fibrotic hypersensitivity pneumonitis

Background

Variable clinical courses make it challenging to predict mortality resulting from fibrotic hypersensitivity pneumonitis (HP). This study evaluated the usefulness of radiologic parameters for predicting mortality in patients with fibrotic HP.

Methods

Clinical data and high-resolution computed tomography (HRCT) images, which were scored for reticulation, honeycombing, ground glass opacity (GGO), consolidation, and mosaic attenuation (MA) by visual assessment, were retrospectively analyzed in a total of 101 patients with fibrotic HP (all biopsy-proven cases). Fibrosis score was defined as the sum of reticulation and honeycombing scores.

Results

The mean age of the 101 patients was 58.9 years, and 60.4% were females. During the follow-up (median: 55.5 months; interquartile range: 37.7-89.0 months), the 1-, 3-and 5-year mortality rates were 3.9, 16.8, and 32.7%, respectively. The non-survivors were older and had significantly lower lung function and minimum oxygen saturation during the 6-min walk test than the survivors. The non-survivors had higher scores of reticulation, honeycombing, GGO, fibrosis, and MA on HRCT than survivors. In the multivariable Cox analysis, reticulation, GGO, and fibrosis scores were independent prognostic factors for mortality in patients with fibrotic HP, as well as age. Fibrosis score showed great performance for predicting the 5-year mortality (AUC = 0.752, p < 0.001) and higher mortality was recorded for patients with high fibrosis score (≥12.0%) (the mean survival time: 58.3 vs. 146.7 months, p < 0.01) than those without.

Conclusion

Our results suggest that radiologic fibrosis score may be a useful predictor of mortality in patients with fibrotic HP.

Do handgrip strength and dexterity predict respiratory function in neuromuscular disease?

BACKGROUND

Neuromuscular diseases are acquired or inherited diseases that affect the function of the muscles in our body, including respiratory muscles.

OBJECTIVE

We aimed to discover more cost-effective and practical tools to predict respiratory function status, which causes serious problems with patients with neuromuscular disease.

METHODS

The Vignos and Brooke Upper Extremity Functional Scales were used to evaluate functional status for patient recruitment. The handgrip strength and dexterity of patients were measured using a dynamometer and nine-hole peg test. Respiratory function parameters: forced vital capacity, forced expiratory volume in one second, and peak expiratory flow were evaluated using spirometry.

RESULTS

The mean age of the 30 patients was 11.5 ± 3.79 years old. Significant relationships were found between nine-hole-peg-test scores and respiratory function parameters on both sides. Significant correlations were found between both handgrip strength and respiratory function parameters (p < 0.05). In the linear regression analysis, it was seen that the forced expiratory volume in 1 second, and peak expiratory flow values could be explained in different percentages (p < 0.05).

CONCLUSIONS

Handgrip strength and dexterity measurements can be used as indicators for estimating respiratory function parameters in terms of cost and accessibility, although it is known that they will not replace respiratory function tests.

Lung volumes measurement using novel pressure derived method in participants with obstructive, restrictive and healthy lungs

Background.Lung volumes can be measured by body plethysmography (BP), by inert gas dilution during a single-breath or multiple breaths and by radiographic methods based on chest roentgenogram or CT scanning. Our objective was to analyze the concordance between several methods including a new pressure-derived method (PDM) in a variety of pulmonary conditions.Methods. We recruited four groups of adult volunteers at the chronic obstructive pulmonary disease and tobacco clinic of a respiratory referral hospital: patients with lung bullae, with obstructive lung diseases, with restrictive lung diseases and healthy controls; all subjects underwent lung volume measurements according to ATS/ERS standards in random order with each method and then CT scanning. Differences among groups were estimated by Kruskal-Wallis tests. Concordance correlation coefficients (CCC) and Bland-Altman plots were performed.Results. Sixty-two patients were studied including 15 with lung bullae, 14 with obstructive lung diseases, 12 with restrictive lung disease and 21 healthy subjects. Highest concordance was obtained between BP and CT scanning (CCC 0.95, mean difference -0.35 l) and the lowest, with TLC-DLCO_sb(CCC 0.65, difference -1.05 l). TLC measured by BP had a moderate concordance with the PDM (CCC = 0.91, mean difference -0.19 l). The PDM on the other hand had the lowest intra-test repeatability (2.7%) of all tested methods.Conclusions. Lung volumes measured by BP and CT had high concordance in the scenario of varied pulmonary conditions including lung bullae, restrictive and obstructive diseases. The new PDM device, had low intra-test variability, and was easy to perform, with a reasonable concordance with BP.

Validation of the clinical utility of sGaw as a response variable in methacholine challenge testing

BACKGROUND AND OBJECTIVE

Airway hyperresponsiveness (AHR) is commonly assessed by a methacholine challenge test (MCT), during which a provocative concentration causing a 20% reduction in forced expiratory volume in 1 second (FEV₁ ) (PC₂₀ ) < 8 mg/ml is considered a positive response. However, a fall in specific airway conductance (sGaw) may also have clinical significance. The purpose of this study was to assess whether AHR determined by a provocative concentration causing a 40% reduction in sGaw (PC₄₀ ) < 8 mg/ml corresponds to a clinical diagnosis of asthma.

METHODS

We analysed the changes in spirometry, lung volumes and sGaw during MCT in 211 randomly selected patients being evaluated for AHR to support a clinical diagnosis of asthma.

RESULTS

The mean (SD) age of the group was 53 (15) years, with 141 women (67%). Overall lung function was normal, with FEV₁  = 92 (15) % predicted, total lung capacity = 97 (13) % predicted and sGaw = 0.19 (0.15-0.23) L/s/cm H₂ O/L, (median, 25-75 IQR). There were many more patients who responded by PC₄₀ only (n = 120) than who responded by PC₂₀ (n = 52). There was no significant difference in asthma diagnosis between the PC₂₀ (98%) and PC₄₀ (93%) groups, and we estimate 34% of patients with a diagnosis of asthma would have been classified as having no AHR if only the FEV₁ criterion was used.

CONCLUSION

Changes in sGaw during MCT indicate clinically significant AHR in support of a clinical diagnosis of asthma among patients being evaluated for asthma.

Stabilising function of the human diaphragm in response to involuntary augmented breaths induced with or without lower-limb movements

NEW FINDINGS

What is the central question of this study? Is the stabilising function of the diaphragm altered differentially in response to involuntary augmented breaths induced with or without lower-limb movements? What is the main finding and its importance? At equivalent levels of ventilation, the diaphragm generated higher passive pressure but moved significantly less during incremental cycle ergometry compared with progressive hypercapnia. Diaphragm excursion velocity and power output did not differ between the two tasks. These findings imply that the power output of the diaphragm during stabilising tasks involving the lower limbs may be preserved via coordinated changes in contractile shortening.

ABSTRACT

Activity of key respiratory muscles, such as the diaphragm, must balance the demands of ventilation with the maintenance of stable posture. Our aim was to test whether the stabilising function of the diaphragm would be altered differentially in response to involuntary augmented breaths induced with or without lower-limb movements. Ten healthy volunteers (age 21 (2) years; mean (SD)) performed progressive CO₂ -rebreathe (5% CO₂ , 95% O₂ ) followed 20 min later by incremental cycle exercise (15-30 W/min), both in a semi-recumbent position. Ventilatory indices, intrathoracic pressures and ultrasonographic measures of diaphragm shortening were assessed before, during and after each task. From rest to iso-time, inspiratory tidal volume and minute ventilation increased two- to threefold. At equivalent levels of tidal volume and minute ventilation, mean inspiratory transdiaphragmatic pressure ( P ¯ di ${\bar P_{{\rm{di}}}}$ ) was consistently higher during exercise compared with CO₂ -rebreathe due to larger increases in gastric pressure and the passive component of P ¯ di ${\bar P_{{\rm{di}}}}$ (i.e., mechanical output due to static contractions), and yet diaphragm excursion was consistently lower. This lower excursion during exercise was accompanied by a reduction in excursion time with no difference in the active component of P ¯ di ${\bar P_{{\rm{di}}}}$ . Consequently, the rates of increase in excursion velocity (excursion/time) and power output (active P ¯ di ${\bar P_{{\rm{di}}}}$ × velocity) did not differ between the two tasks. In conclusion, the power output of the human diaphragm during dynamic lower-limb exercise appears to be preserved via coordinated changes in contractile shortening. The findings may have significance in settings where the ventilatory and stabilising functions of the diaphragm must be balanced (e.g., rehabilitation).

Mechanical effects of obesity on central and peripheral airway resistance in nonasthmatic early pubescent children

BACKGROUND

In children, obesity typically reduces functional residual capacity (FRC), which reduces airway caliber and increases airway resistance. Whether these obesity-related changes in respiratory function can alter bronchodilator responsiveness is unknown.

OBJECTIVE

To investigate bronchodilator responsiveness in nonasthmatic children with and without obesity.

METHODS

Seventy nonasthmatic children, 8-12 years old, without (n = 19) and with (n = 51) obesity, completed spirometry, impulse oscillometry, and airway resistance measurements through plethysmography pre/post 360 µg of inhaled albuterol. FRC was assessed pre albuterol. A two-way analysis of variance determined the effects of obesity (group) and inhaled albuterol (pre-post) on outcome measures.

RESULTS

FRC (%total lung capacity) was 16% lower in children with obesity compared with those without obesity. There was no significant group by pre-post albuterol interaction on any outcome variables. Albuterol inhalation reduced total, central and peripheral airway resistance and increased airway reactance (i.e., less negative) to a similar degree in children with and without obesity. In children with obesity, airway resistance was increased whether measured by impulse oscillometry or plethysmography. However, once airway resistance was adjusted for lung volumes (i.e., specific airway resistance or sRaw ), there were no differences between children with and without obesity. In addition, significant but moderate associations were detected between chest mass and FRC (r = -0.566; p < 0.001), FRC and total airway resistance (i.e., Raw ; r = -0.445; p < 0.001).

CONCLUSIONS

In nonasthmatic early pubescent children, obesity increases total, central, and peripheral respiratory system resistance. However, the added respiratory system resistance and low lung volume breathing with obesity are not sufficient to reduce bronchodilator responsiveness.

Reversal of collateral ventilation using endoscopic polymer foam in COPD patients undergoing endoscopic lung volume reduction with endobronchial valves: A controlled parallel group trial

BACKGROUND AND OBJECTIVE

We have previously described reversal of collateral ventilation (CV) in a severe chronic obstructive pulmonary disease (COPD) patient with endoscopic polymer foam (EPF), prior to endoscopic lung volume reduction (ELVR) with valves. The aim of this study was to investigate the efficacy of this in a larger cohort and compare outcomes with a similar cohort with no CV.

METHODS

Patients with severe COPD, with the left upper lobe (LUL) targeted for ELVR, were assessed for CV with high resolution computed tomography (HRCT). If fissure completeness was >95% they were enrolled as controls for valves alone (endobronchial valve control group [EBV-CTRL]). If fissure completeness was 80%-95%, defects were mapped to the corresponding segment, where EPF was instilled following confirmation of CV with CHARTIS. EBVs were inserted 1 month afterwards.

RESULTS

Fourteen patients were enrolled into both arms. After 6 months, there were significant improvements in both groups in forced expiratory volume in 1 s (FEV1; +19.7% EPF vs. +27.7% EBV-CTRL, p < 0.05); residual volume (RV; -16.2% EPF vs. -20.1% EBV-CTRL, p = NS); SGRQ (-15.1 EPF vs. -16.6 EBV-CTRL p = NS) and 6 min walk (+25.8% EPF [77.2 m] vs. +28.4% [82.3 m] EBV-CTRL p = NS). Patients with fissural defects mapped to the lingula had better outcomes than those mapped to other segments (FEV1 +22.9% vs. +16.3% p < 0.05). There were no serious adverse reactions to EPF.

CONCLUSION

EPF successfully reverses CV in severe COPD patients with a left oblique fissure that is 80%-95% complete. Following EBV, outcomes are similar to patients with complete fissures undergoing ELVR with EBV alone. EPF therapy to reverse CV potentially increases the number of COPD patients suitable for ELVR with minimal adverse reactions.

Hierarchical stratification of the factors related to exertional dyspnoea and exercise intolerance in male COPD patients

BACKGROUND

The order and extent of interactions across the factors affecting exertional dyspnoea (ED) and exercise intolerance (EI) in patients with chronic obstructive pulmonary disease (COPD) are not clear. We hypothesized that lung and non-lung variables were the primary variables, ED was the secondary variable and EI was the tertiary variable.

METHODS

Data on demographics, blood tests, cardiac imaging, lung function tests and invasive dead space fractions (V_D/V_T) during incremental exercise test of 46 male COPD subjects were obtained. These variables were categorized by factor analysis and pair-wise correlation analysis was conducted. The best factor of each category was selected and then multivariate regression was conducted.

RESULTS

Peak tidal inspiratory flow (V_T/T_Ipeak), V_D/V_Tpeak and tidal lung expansion capability, and resting diffusing capacity of the lungs (D_LCO)% predicted were the primary pulmonary factors most related to ED, whereas body mass index (BMI), haemoglobin and cholesterol levels were the primary non-pulmonary factors. In multivariate regression analysis, V_T/T_Ipeak, V_D/V_Tpeak and D_LCO% were the primary factors most related to ED (r² = 0.69); ED was most related to EI (r = -0.74 to -0.83).

CONCLUSION

Using hierarchical stratification and statistical methods may improve understanding of the pathophysiology of ED and EI in patients with COPD. KEY MESSAGESThe pathophysiology of exertional dyspnoea (ED) and exercise intolerance (EI) in chronic obstructive pulmonary disease (COPD) is complex. The order and extent of interactions across factors are not clear. In multivariate regression analysis, we found that tidal inspiratory flow, dead space fraction and resting diffusing capacity of the lungs % but not the non-pulmonary factors affected ED.Using correlation coefficients, we further found that ED was the secondary variable and EI was the tertiary variable.Hierarchical stratification of the important factors associated with ED and EI in patients with COPD clarifies their relationships and could be incorporated into management programmes and outcome studies for these patients.

Influence of bronchopulmonary dysplasia on lung function in adolescents who were born extremely prematurely

OBJECTIVES

To assess if a previous diagnosis of bronchopulmonary dysplasia (BPD) was associated with poorer lung function at 16 to 19 years of age, regardless of whether postnatal corticosteroids had been administered.

WORKING HYPOTHESIS

Infants with BPD will have poorer lung function at 16 to 19 years of age.

STUDY DESIGN

Prospective follow-up study.

PATIENT-SUBJECT SELECTION

One hundred and sixty-one participants aged between 16 and 19 years who were born at less than 29 weeks of gestation; 87 had had BPD.

METHODOLOGY

Lung function was assessed by spirometry (FEV₁ , FVC, FEV₁ /FVC, FEF₇₅ , FEF₅₀ , FEF₂₅ , FEF_{25 -75} , PEF), impulse oscillometry (R5Hz and R20Hz), plethysmography (FRC_pleth , TLC_pleth , RV_pleth ), diffusion capacity of the lungs for carbon monoxide (D_L CO, D_L CO/VA) and lung clearance index (LCI). Questionnaires were used to quantify respiratory symptoms and a shuttle sprint test to assess exercise capacity.

RESULTS

At 16 to 19 years, those who had had a diagnosis of BPD had poorer airway function (FEV₁ , FEF₇₅ , FEF₅₀ , FEF_{25 -75} ) compared to those without. FVC and D_L CO were also poorer in those who had BPD. Those differences remained significant after adjusting for sex, gestational age, and maternal smoking. When excluding those who had received postnatal corticosteroids, differences remained significant in FEV₁ , FVC, and FEF₇₅ . There were no significant differences in exercise capacity or respiratory symptoms between those with and without BPD.

CONCLUSIONS

In adolescents and young adults born prematurely, those who had BPD had poorer lung function compared to those without, regardless of whether they had received postnatal corticosteroids.

Automated quantification system predicts survival in rheumatoid arthritis-associated interstitial lung disease

OBJECTIVE

The prognosis of RA-associated interstitial lung disease (RA-ILD) is difficult to predict because of the variable clinical course. This study aimed to determine the prognostic value of an automated quantification system (AQS) in RA-ILD.

METHODS

We retrospectively analysed the clinical data and high-resolution CT (HRCT) images of 144 patients with RA-ILD. Quantitative lung fibrosis (QLF, sum of reticulation and traction bronchiectasis) and ILD [QILD; sum of QLF, honeycombing (QHC), and ground-glass opacity (QGG)] scores were measured using the AQS.

RESULTS

The mean age was 61.2 years, 43.8% of the patients were male, and the 5-year mortality rate was 30.5% (median follow-up, 52.2 months). Non-survivors showed older age, higher ESR and greater AQS scores than survivors. In multivariable Cox analysis, higher QLF, QHC and QILD scores were independent prognostic factors along with older age and higher ESR. In receiver-operating characteristic curve analysis, the QLF score showed better performance in predicting 5-year mortality than the QHC and QGG scores but was similar to the QILD score. Patients with high QLF scores (≥12% of total lung volume) showed higher 5-year mortality (50% vs 17.4%, P < 0.001) than those with low QLF scores and similar survival outcome to patients with idiopathic pulmonary fibrosis (IPF). Combining with clinical variables (age, ESR) further improved the performance of QLF score in predicting 5-year mortality.

CONCLUSION

QLF scores might be useful for predicting prognosis in patients with RA-ILD. High QLF scores differentiate a poor prognostic phenotype similar to IPF.

Fractional Exhaled Nitric Oxide (FeNO) in Patients with Stable Chronic Obstructive Pulmonary Disease: Short-Term Variability and Potential Clinical Implications

BACKGROUND

The use of fractional exhaled nitric oxide (FeNO) has been proposed for identifying and monitoring eosinophilic airway inflammation in chronic obstructive pulmonary disease (COPD). To explore the clinical utility of FeNO in COPD, we aimed to assess its short-term variability in a clinically stable COPD cohort.

METHODS

Consecutive COPD patients, formerly smokers, underwent FeNO assessment at the baseline and six time-points through serial sampling spaced 3 days apart.

RESULTS

A total of 41 patients (mean age 72.9, 87.8% males) showed a median baseline value of FeNO of 11.7 (8.0-16.8) ppb. A weak linear relationship was documented between baseline FeNO values and both eosinophil counts (r = 0.341, p = 0.029) and the percentage of eosinophils (r = 0.331, p = 0.034), confirmed in multiple linear regressions after adjusting for steroid use. The overall individual variability of FeNO between time-points was 3.90 (2.53-7.29) ppb, with no significant difference in the distribution of FeNO values measured at different time-points (p = 0.204). A total of 28 (68.3%) patients exhibited FeNO always below the 25 ppb cut-off at all determinations, while the remining 13 (31.7%) had at least one value above the established limit. Interestingly, none of these 13 participants had FeNO stably above 25 ppb, all showing at least one normal value during serial sampling. Compared to these patients with more fluctuating values, the 28 with stably normal FeNO only exhibited a significantly higher body weight (80.0 ± 18.2 kg vs. 69.0 ± 8.8 kg, p = 0.013) and body mass index (29.7 ± 6.5 kg/m2 vs. 25.9 ± 3.7 kg/m2, p = 0.026), confirmed in multiple logistic regressions after adjusting for major potential confounders.

CONCLUSIONS

A certain degree of FeNO variability, apparently unrelated to eosinophil counts but somehow influenced by body weight, must be considered in COPD patients. Further studies are needed to clarify whether this biomarker may be effectively used to plan more personalized pharmacological and rehabilitation strategies in this clinical setting.

Long-term respiratory outcomes after COVID-19: a Brazilian cohort study

Objective.

To investigate the prevalence and risk factors for persistent symptoms up to 12 months after hospital discharge in COVID-19 survivors.

Methods.

This prospective cohort study included patients with COVID-19 discharged from a university hospital in Brazil. Follow-up was performed 2, 6, and 12 months after discharge. Lung function tests and chest computed tomography (CT) were performed 2 months after discharge and were repeated if abnormal. The primary outcomes were the symptoms present, work status, and limitations in daily activities.

Results.

Eighty-eight patients were included. Dyspnea (54.5%), fatigue (50.0%), myalgia, and muscle weakness (46.6%) were the most common symptoms, which decreased over time. Anxiety was frequent (46.6%) and remained unchanged. One year after discharge, 43.2% of the patients reported limitations in daily activities, and 17.6% had not returned to work. Corticosteroid use was significantly associated with dyspnea and limitations in daily activities. Females had an increased risk of fatigue at the 12-month assessment, with marginal significance after multivariable adjustment. Young age and bronchial wall thickening on admission CT were also risk factors for dyspnea at follow-up. The most common lung function abnormalities were reduced diffusion capacity and small airway disease, which partially improved over time.

Conclusions.

One year after hospital discharge, more than one-third of patients still had persistent COVID-19-related symptoms, remarkable dyspnea, fatigue, and limitations in daily activities, regardless of acute disease severity. Age, female sex, corticosteroid use during hospitalization, and bronchial thickening on admission CT were associated with an increased risk of sequelae.

Factors Predictive for Immunomodulatory Therapy Response and Survival in Patients with Hypersensitivity Pneumonitis-Retrospective Cohort Analysis

Hypersensitivity pneumonitis (HP) is one of the interstitial lung diseases with clearly established diagnostic criteria. Nevertheless, pharmacologic treatment recommendations are still lacking. Most specialists use steroids as first-line drugs, sometimes combined with an immunosuppressive agent. Aim: The aim of the present retrospective study was to establish predictive factors for treatment success and survival advantage in HP patients. Methods: We analyzed the short-term treatment outcome and overall survival in consecutive HP patients treated with prednisone alone or combined with azathioprine. Results: The study group consisted of 93 HP patients, 54 (58%) with fibrotic HP and 39 (42%) with non-fibrotic HP. Mean (± SD) VCmax % pred. and TL,co % pred. before treatment initiation were 81.5 (±20.8)% and 48.3 (±15.7)%, respectively. Mean relative VCmax and TL,co change after 3−6 months of therapy were 9.5 (±18.8)% and 21.4 (±35.2)%, respectively. The short-term treatment outcomes were improvement in 49 (53%) patients, stabilization in 16 (17%) patients, and progression in 28 (30%) patients. Among those with fibrotic HP, improvement was noted in 19 (35%) cases. Significant positive treatment outcome predictors were fever after antigen exposure, lymphocyte count in broncho-alveolar lavage fluid (BALF) exceeding 54%, RV/TLC > 120% pred., and ill-defined centrilobular nodules in high-resolution computed tomography (HRCT). An increased eosinophil count in BALF and fibrosis in HRCT were significant negative treatment outcome predictors. The presence of fibrosis in HRCT remained significant in a multivariate analysis. A positive response to treatment, as well as preserved baseline VCmax (% pred.) and TLC (% pred.), predicted longer survival, while fibrosis in HRCT was related to a worse prognosis. Conclusion: Immunomodulatory treatment may be effective in a significant proportion of patients with HP, including those with fibrotic changes in HRCT. Therefore, future trials are urgently needed to establish the role of immunosuppressive treatment in fibrotic HP.

Mid-term pulmonary sequelae after hospitalisation for COVID-19: The French SISCOVID cohort

Background

Methods

Results

Conclusion

Pulmonary MRI and Cluster Analysis Help Identify Novel Asthma Phenotypes

BACKGROUND

Outside eosinophilia, current clinical asthma phenotypes do not show strong relationships with disease pathogenesis or treatment responses. While chest x-ray computed tomography (CT) phenotypes have previously been explored, functional MRI measurements provide complementary phenotypic information.

PURPOSE

To derive novel data-driven asthma phenotypic clusters using functional MRI airway biomarkers that better describe airway pathologies in patients.

STUDY TYPE

Retrospective.

POPULATION

A total of 45 patients with asthma who underwent post-bronchodilator ¹²⁹ Xe MRI, volume-matched CT, spirometry and plethysmography within a 90-minute visit.

FIELD STRENGTH/SEQUENCE

Three-dimensional gradient-recalled echo ¹²⁹ Xe ventilation sequence at 3 T.

ASSESSMENT

We measured MRI ventilation defect percent (VDP), CT airway wall-area percent (WA%), wall-thickness (WT, WT* [*normalized for age/sex/height]), lumen-area (LA), lumen-diameter (D, D*) and total airway count (TAC). Univariate relationships were utilized to select variables for k-means cluster analysis and phenotypic subgroup generation. Spirometry and plethysmography measurements were compared across imaging-based clusters.

STATISTICAL TESTS

Spearman correlation (ρ), one-way analysis of variance (ANOVA) or Kruskal-Wallis tests with post hoc Bonferroni correction for multiple comparisons, significance level 0.05.

RESULTS

Based on limited common variance (Kaiser-Meyer-Olkin-measure = 0.44), four unique clusters were generated using MRI VDP, TAC, WT* and D* (52 ± 14 years, 27 female). Imaging measurements were significantly different across clusters as was the forced expiratory volume in 1-second (FEV₁ %_pred ), residual volume/total lung capacity and airways resistance. Asthma-control (P = 0.9), quality-of-life scores (P = 0.7) and the proportions of severe-asthma (P = 0.4) were not significantly different. Cluster1 (n = 15/8 female) reflected mildly abnormal CT airway measurements and FEV₁ with moderately abnormal VDP. Cluster2 (n = 12/12 female) reflected moderately abnormal TAC, WT and FEV₁ . In Cluster3 and Cluster4 (n = 14/6 female, n = 4/1 female, respectively), there was severely reduced TAC, D and FEV₁ , but Cluster4 also had significantly worse, severely abnormal VDP (7 ± 5% vs. 41 ± 12%).

DATA CONCLUSION

We generated four proof-of-concept MRI-derived clusters of asthma with distinct structure-function pathologies. Cluster analysis of asthma using ¹²⁹ Xe MRI in combination with CT biomarkers is feasible and may challenge currently used paradigms for asthma phenotyping and treatment decisions.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage.

Lung ultrasound in the follow-up of severe COVID-19 pneumonia: six months evaluation and comparison with CT

While lung ultrasonography (LUS) proved to be a useful diagnostic and prognostic tool in acute phase of COVID 19 pneumonia, its role in detecting long-term pulmonary sequelae has yet to be explored. In our prospective observational study we assessed the potential of LUS in detecting the presence of computed tomography (CT) fibrotic-like changes after 6 months from COVID-19 pneumonia. Patients who were discharged with a diagnosis of severe COVID-19 pneumonia were enrolled. After 6 months from hospital discharge they underwent LUS, chest CT scan and pulmonary function tests. A logistic regression analysis was performed to assess the association between presence of symptoms, LUS score and diffusing capacity for carbon monoxide (DLCO) at 6-month after hospital discharge and CT scan fibrotic-like changes. A second logistic model was performed to assess the value of some predefined baseline factors (age, sex, worst PaO2/FiO2, ventilator support, worst CRP value, worst D-dimer value and worst LUS score during hospitalization) to predict fibrotic-like changes on 6-month CT scan. Seventy-four patients were enrolled in the study. Twenty-four (32%) showed lung abnormalities suitable for fibrotic-like changes. At multivariate logistic regression analysis LUS score after 6 months from acute disease was significantly associated with fibrotic-like pattern on CT scan. The second logistic model showed that D-dimer value was the only baseline predictive variable of fibrotic-like changes at multivariate analysis. LUS performed after 6 months from severe COVID-19 pneumonia may be a promising tool for detection and follow-up of pulmonary fibrotic sequelae.

Cardiopulmonary work up of patients with and without fatigue 6 months after COVID-19

The pathogenesis of long-Covid symptoms remains incompletely understood. Therefore, we aimed to determine cardiopulmonary limitations 6 months after surviving COVID-19 using pulmonary function tests, echocardiographic studies to the point of analysis of global-longitudinal-strain (GLS), which describes the cycling myocardium deformation and provides better data on left ventricular (LV) dysfunction than LV ejection fraction (LVEF), and validated questionnaires. Overall, 60 consecutive hospitalized patients were included (61 ± 2 years, 40% treated in the ICU). At follow-up (194 ± 3 days after discharge), fatigue was the most prevalent symptom (28%). Patients with fatigue were more symptomatic overall and characterized by worse quality of life (QoL) scores compared to patients without fatigue (all p < 0.05), mainly due to limited mobility and high symptom burden. While PFT variables and LVEF were normal in the vast majority of patients (LVEF = 52% (45-52%)), GLS was significantly reduced (- 15% (- 18 to - 14%)). However, GLS values were not different between patients with and without fatigue. In conclusion, fatigue was the most prevalent long-Covid symptom in our cohort, which was associated with worse QoL mainly due to limited mobility and the high burden of concomitant symptoms. Patients showed a subtle myocardial dysfunction 6 months after surviving COVID-19, but this did not relate to the presence of fatigue.

Pulmonary function tests reveal unrecognised lung dysfunction and have independent prognostic significance in patients with systemic AL amyloidosis

BACKGROUND

Lung involvement in AL amyloidosis is not very common, but post-mortem data and retrospective studies suggest it is likely underrecognized.

AIM

To perform a comprehensive evaluation of lung function with pulmonary function tests (PFTs) in patients with newly diagnosed AL amyloidosis.

METHODS

A prospective, non-interventional study of 139 consecutive patients with newly diagnosed AL amyloidosis.

RESULTS

PFTs indicated normal breathing physiology in 68% of patients, obstructive in 9% and restrictive in 23%; the latter was associated with worse survival (28.6 vs 76 months for obstructive/normal physiology, p = 0.002) and remained significant after adjustment for Mayo stage and abnormal chest-CT. Forced vital capacity <80% of predicted value, forced expiratory volume <80% of predicted value, and carbon monoxide diffusion capacity <70% were independently associated with poorer survival. Respiratory muscle strength (as assessed by maximal expiratory (Pe) and inspiratory (Pi) pressure) was affected in most patients (64% had Pi < 55% and 57% had Pe < 70% of predicted values). Pe% was an independent prognostic factor for survival (HR: 0.984 per 1% unit increase, p = 0.007).

CONCLUSIONS

Pulmonary dysfunction, as assessed with PFTs, is common and underrecognized in patients with systemic AL amyloidosis, with significant prognostic and potentially therapeutic implications, independent of the degree of cardiac dysfunction or chest-CT findings.

Bronchodilator Responsiveness Defined by the 2005 and 2021 ERS/ATS Criteria in Patients with Asthma as Well as Chronic Obstructive Pulmonary Disease

Background

In the 2021 ERS/ATS interpretive strategies for routine lung function tests, a positive bronchodilator response (BDR) was updated as a change of >10% relative to the predicted value in forced expiratory volume in 1 second (FEV₁) or forced vital capacity (FVC). We aimed to explore the differences between the 2005 and 2021 ERS/ATS criteria applied to patients with asthma as well as chronic obstructive pulmonary disease (COPD).

Methods

BDR test data about asthma patients aged 6–80 years and COPD patients aged 18–80 years were derived from the National Respiratory Medicine Center, First Affiliated Hospital of Guangzhou Medical University, from January 2017 to March 2022. BDR results defined by the 2005 and 2021 ERS/ATS criteria were named 2005-BDR and 2021-BDR, respectively. We compared differences between 2005-BDR and 2021-BDR and analyzed the trend in the proportion of positive BDR (BDR+) with the level of airflow obstruction.

Results

A total of 4457 patients with asthma and 7764 patients with COPD were included in the analysis. The percentages of 2005-BDR+ and 2021-BDR+ were 63.32% and 52.84% for asthma, 30.92% and 22.94% for COPD, respectively. Of patients with 2005-BDR+, 81.86% for asthma and 70.18% for COPD showed 2021-BDR+ results, and these patients had higher FEV₁%pred, FVC%pred (all P<0.05). Whichever BDR criterion was adopted, the proportion of BDR+ had an upward linear trend with the increased degree of airflow obstruction in COPD, but exhibited an approximate inverted U-shaped curve in asthma. In COPD, the proportion of BDR_FEV1 was negatively associated with the degree of airflow obstruction, while BDR_FVC was positively associated (all P<0.05).

Conclusion

Compared with 2005-BDR+, the proportion of 2021-BDR+ reduced markedly in patients with asthma and COPD, but their trends with the degree of airflow obstruction did not change. Patients with consistent BDR+ had higher initial FEV₁%pred and FVC%pred.

Non-Invasive Assessment of Right Ventricle to Arterial Coupling for Prognosis Stratification of Fibrotic Interstitial Lung Diseases

Background: The coupling of the right ventricle (RV) to the pulmonary circulation is an indicator of RV performance that can be non-invasively estimated by echocardiography. There are no data about its use in patients affected by fibrotic interstitial lung diseases (f-ILD). Methods: Fifty f-ILD patients, including 27 cases with idiopathic pulmonary fibrosis (IPF) (M = 37; mean age 67 ± 7 years), were studied with standard and speckle-tracking echocardiography and compared with 30 age-matched healthy volunteers. The mean patient follow-up was 70 ± 4 months. Results: Fibrotic ILD patients had a larger right ventricle (RV) and worse diastolic function because the RV global longitudinal strain (GLS) was significantly lower and the systolic pulmonary artery pressure (sPAP) estimates were higher in comparison with those of controls. Conversely, tricuspid annular systolic excursion (TAPSE) did not differ between controls and patients. Median values of TAPSE/sPAP and RV GLS/sPAP were significantly reduced in f-ILD patients (p < 0.0001). Patients with an RV GLS/sPAP below the median value had a shorter survival time (61 vs. 74 months, p = 0.01); this parameter was an independent predictor of a worse outcome. Conclusion: Low estimates of RV GLS/sPAP are predictive of worse outcomes in f-ILD patients. RV coupling seems to be a promising surrogate biomarker of RV performance to discriminate the patient phenotype with significant management and prognosis implications.

Benefits of Cardio-Pulmonary Rehabilitation in Moderate to Severe Forms of COVID-19 Infection

Our aim was to evaluate the benefits of cardio-pulmonary rehabilitation on severe to moderate COVID-19 patients. 25 discharged COVID-19 patients underwent a cardio-pulmonary test (CPET), a spirometry test and a measure of carbon monoxide lung diffusion capacity (DLCO) at the beginning of their rehabilitation program and after 23 ± 5 rehabilitation sessions. This rehabilitation program combined interval training exercises on a bike and resistance exercises for major muscle groups. We then compared their progress in rehabilitation to that obtained with cardiac patients. At the beginning of their rehabilitation program, COVID-19 patients presented a reduced physical capacity with a maximal aerobic capacity (VO₂ max) at 71% of predicted value, a maximal workload at 70% of predicted value and an exercise hyperventilation measured by a higher VE/VCO₂ slope. Exercise was mainly limited by muscle deconditioning. After rehabilitation, the VO₂ max and maximal workload increased in COVID 19 patients by 18% and 26%, respectively. In patients with ischemic heart disease the post-rehabilitation gains in VO2 max and maximal workload were 22% and 25%, respectively. Moreover, exercise hyperventilation decreased by 10% in both groups. On the other hand, the intrinsic pulmonary function of COVID 19 patients improved following natural recovery. In conclusion, even if cardio-pulmonary rehabilitation is probably not the only parameter which explains the partial recovery of moderate to severe COVID-19 patients, it certainly helps to improve their physical capacity and reduce exercise hyperventilation.

Longitudinal Analysis of Quadriceps Muscle Strength in Patients with Previous COVID-19 Hospitalization and in Patients with Post-Acute Sequelae following Mild COVID-19

Muscle weakness is a prominent symptom in post-acute sequelae of COVID-19 (PASC). However, few studies have objectively and longitudinally assessed muscle strength after varying COVID-19 severity grades. This observational study aimed to explore the prevalence, determinants, and 1.5 years change of quadriceps muscle weakness in 98 patients discharged from COVID-19 hospitalization and in 50 patients with PASC following mild COVID-19. Isometric quadriceps maximal voluntary contraction (MVC) was assessed on a computerized dynamometer at three visits. Also, in a subgroup of 14 post-COVID-19 patients with quadriceps muscle weakness, muscle thickness and echo intensity were determined by muscle ultrasound of nine upper and lower extremity muscles. Muscle weakness was found in 59% of post-hospitalized patients and in 65% of those with PASC following mild COVID-19 at ~14 weeks after acute COVID-19. Whereas during ~1.5 years follow-up MVC modestly improved, muscle weakness prevalence remained unchanged. Hospital length of stay and diabetes mellitus were identified as possible predictors of muscle weakness following COVID-19 hospitalization. No predictors could be identified in those with PASC following mild COVID-19. Ultrasound outcomes revealed no large structural abnormalities. In conclusion, clinically relevant muscle weakness is common after COVID-19 and its long-term improvement is poor. Future studies with relevant control groups are warranted to confirm our data.

Oropharyngeal obstruction and respiratory system compliance are linked to ventilatory control parameters in pediatric obstructive sleep apnea syndrome

Instable ventilatory control is an endotypic trait of obstructive sleep apnea syndrome (OSAS). This study aimed to evaluate the relationships between the anatomical compromise of the upper (oro- and naso-pharynx) and lower airways and ventilatory control (measured by chemical loop gain) in otherwise healthy children suffering from moderate to severe OSAS (apnea hypopnea index ≥ 5/hour). The children underwent ear, nose and throat examination, measurement of impedance of the respiratory system that allowed characterizing peripheral lung mechanics using the extended Resistance-Inertance-Compliance model. Physiologically constrained analytical model based on tidal breathing analysis allowed for the computation of steady-state plant gain, steady-state controller gain (CG0) and steady-state loop gain (LG0). Medium-frequency components of the feedback control system were then deduced. Fifty children (median age 11.2 years) were enrolled. Oropharyngeal obstruction was associated with decreased CG0 (0.6 [0.2; 1.0] vs 1.5 [0.5; 6.6] L.s^- 1.mmHg^- 1, p = 0.038) and LG0 (0.4 [0.2; 1.1] vs 1.2 [0.4; 9.3], p = 0.027), while nasal obstruction did not modify ventilatory control parameters. In a multivariate analysis Medium-Frequency PG was negatively related to minute ventilation and respiratory system compliance. Both upper (tonsil hypertrophy) and lower (compliance of respiratory system) airways are linked to ventilatory control in children with moderate to severe OSAS.

Tidal volume expandability affected by flow, dynamic hyperinflation, and quasi-fixed inspiratory time in patients with COPD and healthy individuals

Exertional dyspnea (ED) and impaired exercise performance (EP) are mainly caused by dynamic hyperinflation (DH) in chronic obstructive pulmonary disease (COPD) patients by constraining tidal volume expansion at peak exercise (V_Tpeak). As V_Tpeak is the product of inspiratory time (T_Ipeak) and flow (V_T/T_Ipeak), it was hypothesized that V_Tpeak and V_Tpeak/total lung capacity (V_Tpeak/TLC) may be affected by T_Ipeak and V_T/T_Ipeak. Hence, the study investigated the (1) effect of T_Ipeak and V_T/T_Ipeak on V_Tpeak expansion, (2) factors associated with T_Ipeak, expiratory time (T_Epeak), V_T/T_Ipeak, and V_Tpeak/TLC, and (3) relationships between V_T/T_Ipeak and V_Tpeak/TLC with ED and EP in COPD patients and controls. The study enrolled 126 male stable COPD patients and 33 sex-matched controls. At peak exercise, T_Ipeak was similar in all subjects (COPD versus controls, mean ± SD: 0.78 ± 0.17 s versus 0.81 ± 0.20 s, p = NS), whereas the COPD group had lower V_T/T_Ipeak (1.71 ± 0.49 L/s versus 2.58 ± 0.69 L/s, p < .0001) and thus the COPD group had smaller V_Tpeak (1.31 ± 0.34 L versus 2.01 ± 0.45 L,p < .0001) and V_Tpeak/TLC (0.22 ± 0.06 vs 0.33 ± 0.05, p < .0001). T_Ipeak, T_Epeak, and V_T/T_Ipeak were mainly affected by exercise effort, whereas V_Tpeak/TLC was not. T_Epeak, V_T/T_Ipeak, and V_Tpeak/TLC were inversely changed by impaired lung function. T_Ipeak was not affected by lung function. Dynamic hyperinflation did not occur in the controls, however, V_Tpeak/TLC was strongly inversely related to DH (r = −0.79) and moderately to strongly related to lung function, ED, and EP in the COPD group. There was a slightly stronger correlation between V_Tpeak/TLC with ED and EP than V_T/T_Ipeak in the COPD group (|r| = 0.55–0.56 vs 0.38–0.43). In summary, T_Ipeak was similar in both groups and the key to understanding how flow affects lung expansion. However, the DH volume effect was more important than the flow effect on ED and EP in the COPD group.

The efficacy of trunk bracing with an instrumented corrective exercise on spinal deformity, pulmonary function, trunk muscle endurance and quality of life in adolescent idiopathic scoliosis: Protocol for a parallel-groups clinical study (Preprint)

BACKGROUND

Adolescent idiopathic scoliosis is a 3D spine distortion with an unidentified etiology. It results in noticeable trunk deformity, decreased muscle strength and endurance at the trunk, changes in chest volume, breathing issues, and ultimately a decline in the quality of life. Trunk bracing and corrective exercises make up most of the treatment of patients with scoliosis when their deformity is between 20° and 45°, and they have not yet attained skeletal maturity. Evidence suggests that spinal deformity in people with scoliosis may result from improper motor control. Automatic response training is an exercise therapy technique that can modify the pattern of trunk muscle control for supporting the spinal column in normal alignment. An apparatus called a cantilever device is required for this type of exercise, which facilitates training at home. In spite of research showing the benefit of braces and therapeutic exercise in adolescents with scoliosis, less emphasis has been given to the impact of home-based training, especially when this intervention is paired with braces.

OBJECTIVE

We aim to compare the efficacy of bracing and a conventional exercise program to a combination treatment that includes trunk bracing and exercises with a cantilever device performed at home on the degree of spine curvature, pulmonary function, trunk muscular endurance, and quality of life.

METHODS

This study was a 2-arms parallel-group clinical study. A total of 16 adolescents with idiopathic scoliosis and single lumbar and thoracolumbar curves of 20°-45° were recruited and randomly assigned into 2 groups. Group A received a combination of trunk bracing and exercise using an instrument known as a "cantilever." Group B (controls) received trunk bracing and a conventional exercise program (without a tool). The study outcomes were the Cobb angle of the scoliotic curve, pulmonary function, the endurance of the trunk muscles, and quality of life. The study outcomes were measured at 2 time points: before the intervention (T1) and 12 weeks following the start of the intervention (T2; at this time, the intervention period has been completed). Multivariate analysis of variance was used to test between- and within-group differences.

RESULTS

Recruitment for this study began in fall 2022 and is expected to be completed by the end of summer 2023.

CONCLUSIONS

We studied the efficacy of a combined trunk bracing program and postural response exercises using a cantilever device in treating adolescent idiopathic scoliosis and compared it with trunk bracing and conventional home exercises. Exercises performed at home using a cantilever device are anticipated to raise the endurance of trunk muscles, which will help reduce trunk deformity, enhance pulmonary function, and improve the quality of life of participants.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials IRCT20220330054371N1; https://www.irct.ir/trial/62811.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/43265.

Relation of Pulmonary Diffusing Capacity Decline to HRCT and VQ SPECT/CT Findings at Early Follow-Up after COVID-19: A Prospective Cohort Study (The SECURe Study)

A large proportion of patients exhibit persistently reduced pulmonary diffusion capacity after COVID-19. It is unknown whether this is due to a post-COVID restrictive lung disease and/or pulmonary vascular disease. The aim of the current study was to investigate the association between initial COVID-19 severity and haemoglobin-corrected diffusion capacity to carbon monoxide (DLco) reduction at follow-up. Furthermore, to analyse if DLco reduction could be linked to pulmonary fibrosis (PF) and/or thromboembolic disease within the first months after the illness, a total of 67 patients diagnosed with COVID-19 from March to December 2020 were included across three severity groups: 12 not admitted to hospital (Group I), 40 admitted to hospital without intensive care unit (ICU) admission (Group II), and 15 admitted to hospital with ICU admission (Group III). At first follow-up, 5 months post SARS-CoV-2 positive testing/4 months after discharge, lung function testing, including DLco, high-resolution CT chest scan (HRCT) and ventilation-perfusion (VQ) single photon emission computed tomography (SPECT)/CT were conducted. DLco was reduced in 42% of the patients; the prevalence and extent depended on the clinical severity group and was typically observed as part of a restrictive pattern with reduced total lung capacity. Reduced DLco was associated with the extent of ground-glass opacification and signs of PF on HRCT, but not with mismatched perfusion defects on VQ SPECT/CT. The severity-dependent decline in DLco observed early after COVID-19 appears to be caused by restrictive and not pulmonary vascular disease.

Cytokines Profile and Lung Function in Children with Obesity and Asthma: A Case Control Study

The existence of common inflammatory biomarkers linking obesity and asthma in children has been hypothesized. Nevertheless, laboratory and clinical characteristics of children with obesity and asthma are still poorly defined. The primary aim of the present study is to investigate the lung function and the cytokine profile, in children with obesity and asthma. In this prospective, cross-sectional pilot study, pulmonary function tests, biochemical parameters, and serum cytokines levels were compared in three groups of 28 children each, matched for age and sex. Obese children showed normal forced spirometry values except an increased distal airway resistance in subjects with obesity and no asthma. Both groups including obese children showed higher leptin and IL-10 levels and lower adiponectin and TNF-alpha levels compared to children with no obesity and asthma. IL-33 and TGF-beta1 levels were higher in children with obesity and asthma vs. children with normal weight and asthma. Finally, IL-6 was undetectable in approximately 70% of obese children with no asthma, in 57% obese asthmatic children and in 100% of children with normal-weight and asthma. Children with obesity and asthma show the most striking cytokine profile, suggesting a pro-inflammatory role of fat mass in asthma development.

Exercise testing and postoperative complications after minimally invasive lung resection: A cohort study

Background: Peak oxygen uptake (V˙O2) during cardiospulmonary exercise testing (CPET) is used to stratify postoperative risk following lung cancer resection but peak V˙O2 thresholds to predict post-operative mortality and morbidity were derived mostly from patients who underwent thoracotomy.

Objectives: We evaluated whether peak V˙O2 or other CPET-derived variables predict post-operative mortality and cardiopulmonary morbidity after minimally invasive video-assisted thoracoscopic surgery (VATS) for lung cancer resection.

Methods: A retrospective analysis of patients who underwent VATS lung resection between 2002 and 2019 and in whom CPET was performed. Logistic regression models were used to determine predictors of postoperative outcomes until 30 days after surgery. The ability of peak V˙O2 to discriminate between patients with and without post-operative complications was evaluated using Receiver operating characteristic (ROC) analysis.

Results: Among the 593 patients, postoperative cardiopulmonary complications occurred in 92 (15.5%) individuals, including three deaths. Mean peak V˙O2 was 18.8 ml⋅kg⁻¹⋅min⁻¹, ranging from 7.0 to 36.4 ml⋅kg⁻¹⋅min⁻¹. Best predictors of postoperative morbidity and mortality were peripheral arterial disease, bilobectomy or pneumonectomy (versus sublobar resection), preoperative FEV₁, peak V˙O2 , and peak V˙E/V˙CO2. The proportion of patients with peak V˙O2 of < 15 ml⋅kg⁻¹⋅min⁻¹, 15 to < 20 ml⋅kg⁻¹⋅min⁻¹ and ≥ 20 ml⋅kg⁻¹⋅min⁻¹ experiencing at least one postoperative complication was 23.8, 16.3 and 10.4%, respectively. The area under the ROC curve for peak V˙O2 was 0.63 (95% CI: 0.57–0.69).

Conclusion: Although lower peak V˙O2 was a predictor of postoperative complications following VATS lung cancer resection, its ability to discriminate patients with or without complications was limited.

Cardiopulmonary testing in adult patients with β-thalassemia major in comparison to healthy subjects

β-Thalassemia patients often have a reduced capacity of exercise and abnormal respiratory function parameters, but the reasons are unclear. In order to identify the causes of the exercise limitation, we performed a cardiopulmonary exercise testing (CPET) in a group of 54 adult β-thalassemia major (TM) patients without pulmonary arterial hypertension and in a group of healthy control subjects. All subjects underwent cardiac echocardiography and carried out pulmonary function tests. TM patients also filled an IPAQ questionnaire on usual physical activity (PA).Overall, TM patients have a diminished exercise performance in comparison to control subjects. In fact, peak oxygen uptake (V'O₂ peak), expressing maximum exercise capacity, was decreased in 81.5% of the patients; similarly, anaerobic threshold (V'O₂@AT) and O₂ pulse also resulted lowered. In multivariable regression models adjusted for gender, age, BMI, and mean haemoglobin, V'O₂ peak and O₂ pulse were positively associated with cardiac iron overload (T2*). No ventilatory limitation to exercise was observed. The most important causes of exercise limitation in these patients were muscular deconditioning and reduced cardiac inotropism due to iron deposition. Only 15/54 (27.8%) TM patients used to perform vigorous physical activity. These results suggest that a program of regular physical activity may be useful to increase the tolerance to effort and therefore to improve the quality of life in these patients.

[The forced oscillation technique in the functional evaluation of COPD dyspnea]

INTRODUCTION

The goal of the present study is to assess the relationship between functional respiratory parameters measured by the forced oscillation technique (FOT) in COPD patients and (1) dyspnea; (2) inspiratory capacity (IC), along with the variations occurring subsequent to bronchodilation.

METHODS

This cross-sectional study analyzed 40 stable COPD patients. Dyspnea was assessed by means of the San Diego Shortness of Breath Questionnaire. Forced oscillations were measured before and after bronchodilation by means of routine pulmonary function tests (PFTs).

RESULTS

The reactance parameters measured by the FOT correlated with dyspnea (AX5: r=0.46; P=0.003) similarly to IC (r=-0.46; P=0.003). Changes in AX5 following bronchodilation led to a predicted 12% and 200mL improvement in IC, AX5 (area under the ROC curve=0.85, P<0.001).

CONCLUSIONS

Forced oscillation technique (FOT) appears to be an interesting complement to routine PFTs in COPD assessment. Reactance parameters are correlated with dyspnea and their response to bronchodilators is a predictor of significantly improved inspiratory capacity (IC). All in all, FOT may be considered as a functional test with regard to pulmonary hyperinflation, a critical determinant of dyspnea.

Leveraging Therapy-Specific Polygenic Risk Scores to Predict Restrictive Lung Defects in Childhood Cancer Survivors

Therapy-related pulmonary complications are among the leading causes of morbidity among long-term survivors of childhood cancer. Restrictive ventilatory defects (RVD) are prevalent, with risks increasing after exposures to chest radiotherapy and radiomimetic chemotherapies. Using whole-genome sequencing data from 1,728 childhood cancer survivors in the St. Jude Lifetime Cohort Study, we developed and validated a composite RVD risk prediction model that integrates clinical profiles and polygenic risk scores (PRS), including both published lung phenotype PRSs and a novel survivor-specific pharmaco/radiogenomic PRS (surPRS) for RVD risk reflecting gene-by-treatment (GxT) interaction effects. Overall, this new therapy-specific polygenic risk prediction model showed multiple indicators for superior discriminatory accuracy in an independent data set. The surPRS was significantly associated with RVD risk in both training (OR = 1.60, P = 3.7 × 10-10) and validation (OR = 1.44, P = 8.5 × 10-4) data sets. The composite model featuring the surPRS showed the best discriminatory accuracy (AUC = 0.81; 95% CI, 0.76-0.87), a significant improvement (P = 9.0 × 10-3) over clinical risk scores only (AUC = 0.78; 95% CI: 0.72-0.83). The odds of RVD in survivors in the highest quintile of composite model-predicted risk was ∼20-fold higher than those with median predicted risk or less (OR = 20.01, P = 2.2 × 10-16), exceeding the comparable estimate considering nongenetic risk factors only (OR = 9.20, P = 7.4 × 10-11). Inclusion of genetic predictors also selectively improved risk stratification for pulmonary complications across at-risk primary cancer diagnoses (AUCclinical = 0.72; AUCcomposite = 0.80, P = 0.012). Overall, this PRS approach that leverages GxT interaction effects supports late effects risk prediction among childhood cancer survivors.

SIGNIFICANCE

This study develops a therapy-specific polygenic risk prediction model to more precisely identify childhood cancer survivors at high risk for pulmonary complications, which could help improve risk stratification for other late effects.

Physiological Predictors of Morbidity and Mortality in COPD: The Relative Importance of Reduced Inspiratory Capacity and Inspiratory Muscle Strength

Low resting inspiratory capacity (IC) and low maximal inspiratory pressure (MIP) have previously been linked to exertional dyspnea, exercise limitation and poor survival in chronic obstructive pulmonary disease (COPD). The interaction and relative contributions of these two related variables to important clinical outcomes are unknown. The objective of the current study was to examine the interaction between resting IC and MIP (both % predicted), exertional dyspnea, exercise capacity and long-term survival in patients with COPD. Two hundred and eighty-five patients with mild to advanced COPD completed standard lung function testing and a cycle cardiopulmonary exercise test. Multiple regression determined predictors of the exertional dyspnea-ventilation slope and peak oxygen uptake (V̇O_2peak). Cox regression determined predictors of 10-year mortality. IC was associated with the dyspnea-ventilation slope (standardized β=-0.44, p<0.001), while MIP was excluded from the regression model (p=0.713). IC and MIP were included in the final model to predict V̇O_2peak. However, the standardized β was greater for IC (0.49) than MIP (0.22). After adjusting for age, sex, body mass index, cardiovascular risk, airflow obstruction and diffusing capacity, resting IC was independently associated with 10-year all-cause mortality (hazard ratio=1.25, confidence interval_5-95%=1.16-1.34, p<0.001), while MIP was excluded from the final model (all p=0.829). Low resting IC was consistently linked to heightened dyspnea intensity, low V̇O_2peak and worse survival in COPD even after accounting for airway obstruction, inspiratory muscle strength, and diffusing capacity. These results support the use of resting IC as an important physiological biomarker closely linked to key clinical outcomes in COPD.

Model-based Bayesian inference of the ventilation distribution in patients with cystic fibrosis from multiple breath washout, with comparison to ventilation MRI

BACKGROUND

Indices of ventilation heterogeneity (VH) from multiple breath washout (MBW) have been shown to correlate well with VH indices derived from hyperpolarised gas ventilation MRI. Here we report the prediction of ventilation distributions from MBW data using a mathematical model, and the comparison of these predictions with imaging data.

METHODS

We developed computer simulations of the ventilation distribution in the lungs to model MBW measurement with 3 parameters: σ_V, determining the extent of VH; V₀, the lung volume; and V_D, the dead-space volume. These were inferred for each individual from supine MBW data recorded from 25 patients with cystic fibrosis (CF) using approximate Bayesian computation. The fitted models were used to predict the distribution of gas imaged by ³He ventilation MRI measurements collected from the same visit.

RESULTS

The MRI indices measured (I_1/3, the fraction of pixels below one-third of the mean intensity and I_CV, the coefficient of variation of pixel intensity) correlated strongly with those predicted by the MBW model fits (r=0.93,0.88 respectively). There was also good agreement between predicted and measured MRI indices (mean bias ± limits of agreement: I_1/3:-0.003±0.118 and I_CV:-0.004±0.298). Fitted model parameters were robust to truncation of MBW data.

CONCLUSION

We have shown that the ventilation distribution in the lung can be inferred from an MBW signal, and verified this using ventilation MRI. The Bayesian method employed extracts this information with fewer breath cycles than required for LCI, reducing acquisition time required, and gives uncertainty bounds, which are important for clinical decision making.

Dual-energy CT lung perfusion in systemic sclerosis: preliminary experience in 101 patients

OBJECTIVES

To investigate lung perfusion in systemic sclerosis (SSc).

METHODS

The study population included 101 patients who underwent dual-energy CT (DECT) in the follow-up of SSc with pulmonary function tests obtained within 2 months. Fifteen patients had right heart catheterization-proven PH.

RESULTS

Thirty-seven patients had no SSc-related lung involvement (Group A), 56 patients had SSc-related interstitial lung disease (Group B) of variable extent (Group B mild: ≤ 10% of lung parenchyma involved: n = 17; Group B moderate: between 11 and 50%: n = 31; Group B severe: > 50%: n = 8), and 8 patients had PVOD/PCH (Group C). Lung perfusion was abnormal in 8 patients in Group A (21.6%), 14 patients in Group B (25%), and 7 patients in Group C (87.5%). In Group A and Group B mild (n = 54), (a) patients with abnormal lung perfusion (n = 14; 26%) had a higher proportion of NYHA III/IV scores of dyspnea (7 [50%] vs 7 [17.5%]; p = 0.031) and a shorter mean walking distance at the 6MWT (397.0 [291.0; 466.0] vs 495.0 [381.0; 549.0]; p = 0.042) but no evidence of difference in the DLCO% predicted (61.0 [53.0; 67.0] vs 68.0 [61.0; 78.0]; p = 0.055) when compared to patients with normal lung perfusion (n = 40; 74%); (b) a negative correlation was found between the iodine concentration in both lungs and the DLCO% predicted but it did not reach statistical significance (r = -0.27; p = 0.059) and no correlation was found with the PAPs (r = 0.16; p = 0.29) and walking distance during the 6MWT (r = -0.029; p = 0.84).

CONCLUSIONS

DECT lung perfusion provides complementary information to standard HRCT scans, depicting perfusion changes in SSc patients with normal or minimally infiltrated lung parenchyma.

KEY POINTS

• In a retrospective observational study of 101 consecutive patients with SSc, dual-energy CT pulmonary angiography was obtained to evaluate lung perfusion. • Lung perfusion was abnormal in 14 out of 54 patients (26%) with no or mild SSc-related lung infiltration. • Patients with abnormal perfusion and no or mild SSc-related lung infiltration had more severe scores of dyspnea and shorter walking distance than patients with similar lung findings and normal perfusion, suggesting the presence of small vessel vasculopathy.

Exertional dyspnoea in patients with mild-to-severe chronic obstructive pulmonary disease (COPD): Neuromechanical mechanisms

KEY POINTS

Dyspnoea during exercise is a common and troublesome symptom reported by patients with chronic obstructive pulmonary disease (COPD) and is linked to an elevated inspiratory neural drive (IND). The precise mechanisms of elevated IND and dyspnoea across the continuum of airflow obstruction severity in COPD remains unclear. The present study sought to determine the mechanisms of elevated IND [by diaphragm EMG, EMGdi (%max)] and dyspnoea during cardiopulmonary exercise testing (CPET) across the continuum of COPD severity. There was a strong association between increasing dyspnoea intensity and EMGdi (%max) during CPET across the COPD continuum despite significant heterogeneity in underlying pulmonary gas exchange and respiratory mechanical impairments. Critical inspiratory constraints occurred at progressively lower ventilation during exercise with worsening severity of COPD. This was associated with the progressively lower resting inspiratory capacity with worsening disease severity. Earlier critical inspiratory constraint was associated with earlier neuromechanical dissociation and greater likelihood of reporting the sensation of 'unsatisfied inspiration'.

ABSTRACT

In patients with COPD, exertional dyspnoea generally arises when there is imbalance between ventilatory demand and capacity, but the neurophysiological mechanisms are unclear. We therefore determined if disparity between elevated inspiratory neural drive (IND) and tidal volume (V_T ) responses (neuromechanical dissociation) impacted dyspnoea intensity and quality during exercise, across the COPD severity spectrum. In this two-centre, cross-sectional observational study, 89 participants with COPD divided into tertiles of FEV₁ %predicted (Tertile 1 = FEV_1 =  87 ± 9%, Tertile 2 = 60 ± 9%, Tertile 3 = 32 ± 8%) and 18 non-smoking controls, completed a symptom-limited cardiopulmonary exercise tests (CPET) with measurement of IND by diaphragm electromyography [EMGdi (%max)]. The association between increasing dyspnoea intensity and EMGdi (%max) during CPET was strong (r = 0.730, P < 0.001) and not different between the four groups who showed marked heterogeneity in pulmonary gas exchange and mechanical abnormalities. Significant inspiratory constraints (tidal volume/inspiratory capacity (V_T /IC) ≥ 70%) and onset of neuromechanical dissociation (EMGdi (%max):V_T /IC > 0.75) occurred at progressively lower V̇_E from Control to Tertile 3. Lower resting IC meant earlier onset of neuromechanical dissociation, heightened dyspnoea intensity and greater propensity (93% in Tertile 3) to select qualitative descriptors of 'unsatisfied inspiration'. We concluded that, regardless of marked variation in mechanical and pulmonary gas exchange abnormalities in our study sample, exertional dyspnoea intensity was linked to the magnitude of EMGdi (%max). Moreover, onset of critical inspiratory constraints and attendant neuromechanical dissociation amplified dyspnoea intensity at higher exercise intensities. Simple measurements of IC and breathing pattern during CPET provide useful insights into mechanisms of dyspnoea and exercise intolerance in individuals with COPD. Abstract figure legend As chronic obstructive pulmonary disease severity increases, worsening gas exchange and respiratory mechanical impairment causes increased afferent receptor stimulation, increasing inspiratory neural drive at a given ventilation. The widening disparity between progressively greater inspiratory neural drive and reduced ventilatory output causes, 'neuromechanical dissociation'. This is strongly associated with a rapid increase in the intensity of dyspnea during exercise, and the onset of the sensation of 'unsatisfied inspiration'. This article is protected by copyright. All rights reserved.

Small Airways Dysfunction is Associated with Increased Exacerbations in Patients with Asthma

There is poor understanding of why some patients with asthma experience recurrent exacerbations despite high levels of treatment. We compared measurements of peripheral ventilation heterogeneity and respiratory system mechanics in participants with asthma who were differentiated according to exacerbation history, to ascertain whether peripheral airway dysfunction was related to exacerbations. Three asthmatic groups: "Stable" (no exacerbations for >12 months, n=18), "Exacerbation-prone" (≥1 exacerbation requiring systemic corticosteroids within the last 12 months, but stable for ≥1-month, n=9) and "Treated-exacerbation" (exacerbation requiring systemic corticosteroids within the last 1 month, n=12) were studied. All participants were current non-smokers with <10pack/years smoking history. Spirometry, static lung volumes, ventilation heterogeneity from multi-breath nitrogen washout (MBW) and respiratory system mechanics from oscillometry were measured. The Exacerbation-prone group compared to the Stable group had slightly worse spirometry (FEV₁ Z-score -3.58(1.13) vs -2.32(1.06), p=0.03), however acinar ventilation heterogeneity (S_acin Z-score 7.43(8.59) vs 3.63(3.88), p=0.006) and respiratory system reactance (X_rs cmH₂O.s.L^-1 -2.74(3.82) vs -1.32(1.94), p=0.01) were much worse in this group. The Treated-exacerbation group had worse spirometry but similar small airway function, compared with the Stable group. Patients with asthma who exacerbate have worse small airway function as evidenced by increases in S_acin measured by MBW and delta X_rs from oscillometry, both markers of small airway dysfunction, compared with those that do not.

Single dose of budesonide/formoterol turbuhaler compared to salbutamol pMDI for speed of bronchodilator onset in asthma: a randomised cross-over trial

OBJECTIVE

To compare bronchodilator response after to salbutamol and budesonide/formoterol in adults with stable asthma.

METHODS

A double-blind, cross-over, single-centre, placebo-controlled, non-inferiority trial. Adults with stable asthma were randomised to different orders of two treatment regimens: two actuations of placebo via MDI and one actuation of budesonide/formoterol 200/6 µg via turbuhaler; and one actuation of placebo turbuhaler and two actuations of salbutamol 100 µg via MDI. The primary outcome measure was FEV1 after 2 min. Secondary outcome measures included FEV1, mBorg Dyspnoea Scale score and visual analogue score for breathlessness over 30 min.

RESULTS

Forty-nine of 50 potential participants were randomised. One participant withdrew following the first intervention visit and another could not be randomised due to COVID-19 restrictions. The mean (SD) change from baseline FEV1 2 min after treatment administration for budesonide/formoterol and salbutamol was 0.08 (0.14) L, n=49, and 0.17 (0.18) L, n=48, respectively, mean (95% CI) paired difference of -0.097 L (-0.147 to -0.047), p=0.07, against a non-inferiority bound of -0.06 L. In the secondary analysis, FEV1 over 30 min was lower for budesonide/formoterol compared with salbutamol, difference (95% CI): -0.10 (-0.12 to -0.08) L, p<0.001. There were no differences in Visual Analogue Scale score or mBorg Dyspnoea Scale score between treatments.

CONCLUSION

The results do not support the primary hypothesis of non-inferiority at the boundary of -0.06 L for the difference between budesonide/formoterol 200/6 µg compared with salbutamol 200 µg for FEV1 at 2 min, and could be consistent with inferiority with a p value of 0.07. For the secondary analysis of FEV1 measurements over time, the FEV1 was higher with salbutamol.

TRIAL REGISTRATION NUMBER

Australian and New Zealand Clinical Trials Registry (ACTRN 12619001387112).

Air pollution enhance the progression of restrictive lung function impairment and diffusion capacity reduction: an elderly cohort study

BACKGROUND

Some evidences have shown the association between air pollution exposure and the development of interstitial lung diseases. However, the effect of air pollution on the progression of restrictive ventilatory impairment and diffusion capacity reduction is unknown. This study aimed to evaluate the effects of long-term exposure to ambient air pollution on the change rates of total lung capacity, residual volume, and diffusion capacity among the elderly.

METHODS

From 2016 to 2018, single-breath helium dilution with the diffusion capacity of carbon monoxide was performed once per year on 543 elderly individuals. Monthly concentrations of ambient fine particulate matters (PM_2.5) and nitric dioxide (NO₂) at the individual residential address were estimated using a hybrid Kriging/Land-use regression model. Linear mixed models were used to evaluate the association between long-term (12 months) exposure to air pollution and lung function with adjustment for potential covariates, including basic characteristics, indoor air pollution (second-hand smoke, cooking fume, and incense burning), physician diagnosed diseases (asthma and chronic airway diseases), dusty job history, and short-term (lag one month) air pollution exposure.

RESULTS

An interquartile range (5.37 ppb) increase in long-term exposure to NO₂ was associated with an additional rate of decline in total lung volume (- 1.8% per year, 95% CI: - 2.8 to - 0.9%), residual volume (- 3.3% per year, 95% CI: - 5.0 to - 1.6%), ratio of residual volume to total lung volume (- 1.6% per year, 95% CI: - 2.6 to - 0.5%), and diffusion capacity (- 1.1% per year, 95% CI: - 2.0 to - 0.2%). There is no effect on the transfer factor (ratio of diffusion capacity to alveolar volume). The effect of NO₂ remained robust after adjustment for PM_2.5 exposure.

CONCLUSIONS

Long-term exposure to ambient NO₂ is associated with an accelerated decline in static lung volume and diffusion capacity in the elderly. NO₂ related air pollution may be a risk factor for restrictive lung disorders.

Sex Differences in Diaphragm Voluntary Activation after Exercise

INTRODUCTION

The female diaphragm develops less fatigue after high-intensity exercise compared with males. Diaphragm fatigability is typically defined as a decrease in transdiaphragmatic twitch pressure (Pdi,TW) and represents the contractile function of the muscle. However, it is unclear whether this sex difference persists when examining changes in voluntary activation, which represents a neural mechanism contributing to fatigability.

PURPOSE

This study aimed to determine if high-intensity cycling results in a decrease in diaphragm voluntary activation (D-VA) and to explore if the decrease in D-VA is different between sexes.

METHODS

Twenty-five participants (15 females) completed a single bout of high-intensity constant load cycling. D-VA and Pdi,TW were measured before and after exercise using cervical magnetic stimulation of the phrenic nerves to assess diaphragm fatigability.

RESULTS

Participants were of similar aerobic fitness when expressed relative to predicted values (females: 114% ± 25% predicted, males: 111% ± 11% predicted; P = 0.769). Pdi,TW decreased relative to baseline to 85.2% ± 16.7% and 70.3% ± 12.4% baseline (P = 0.012) in females and males, respectively, immediately after exercise. D-VA also decreased in both females and males immediately after exercise. The decrease in D-VA was less in females compared with males (95.4% ± 4.9% baseline vs 87.4% ± 10.8% baseline, respectively; P = 0.018).

CONCLUSIONS

D-VA decreases after whole-body exercise in both females and males, although the magnitude of the decrease is not as large in females compared with males. The findings of this study suggest that the female diaphragm is more resistant to both contractile and neural mechanisms of fatigability after whole-body exercise.

ERS/ATS technical standard on interpretive strategies for routine lung function tests

BACKGROUND

Appropriate interpretation of pulmonary function tests (PFTs) involves the classification of observed values as within/outside the normal range based on a reference population of healthy individuals, integrating knowledge of physiological determinants of test results into functional classifications and integrating patterns with other clinical data to estimate prognosis. In 2005, the American Thoracic Society (ATS) and European Respiratory Society (ERS) jointly adopted technical standards for the interpretation of PFTs. We aimed to update the 2005 recommendations and incorporate evidence from recent literature to establish new standards for PFT interpretation.

METHODS

This technical standards document was developed by an international joint Task Force, appointed by the ERS/ATS with multidisciplinary expertise in conducting and interpreting PFTs and developing international standards. A comprehensive literature review was conducted and published evidence was reviewed.

RESULTS

Recommendations for the choice of reference equations and limits of normal of the healthy population to identify individuals with unusually low or high results are discussed. Interpretation strategies for bronchodilator responsiveness testing, limits of natural changes over time and severity are also updated. Interpretation of measurements made by spirometry, lung volumes and gas transfer are described as they relate to underlying pathophysiology with updated classification protocols of common impairments.

CONCLUSIONS

Interpretation of PFTs must be complemented with clinical expertise and consideration of the inherent biological variability of the test and the uncertainty of the test result to ensure appropriate interpretation of an individual's lung function measurements.