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Sensors (Basel, Switzerland) Nov 2022Precise and accurate measurements of ambient HNO3 are crucial for understanding various atmospheric processes, but its ultra-low trace amounts and the high polarity of...
Precise and accurate measurements of ambient HNO3 are crucial for understanding various atmospheric processes, but its ultra-low trace amounts and the high polarity of HNO3 have strongly hindered routine, widespread, direct measurements of HNO3 and restricted field studies to mostly short-term, localized measurement campaigns. Here, we present a custom field-deployable direct absorption laser spectrometer and demonstrate its analytical capabilities for in situ atmospheric HNO3 measurements. Detailed laboratory characterizations with a particular focus on the instrument response under representative conditions for tropospheric measurements, i.e., the humidity, spectral interference, changing HNO3 amount fractions, and air-sampling-related artifacts, revealed the key aspects of our method: (i) a good linear response (R2 > 0.98) between 0 and 25 nmol·mol−1 in both dry and humid conditions with a limit of detection of 95 pmol·mol−1; (ii) a discrepancy of 20% between the spectroscopically derived amount fractions and indirect measurements using liquid trapping and ion chromatography; (iii) a systematic spectral bias due to water vapor. The spectrometer was deployed in a three-week field measurement campaign to continuously monitor the HNO3 amount fraction in ambient air. The measured values varied between 0.1 ppb and 0.8 ppb and correlated well with the daily total nitrates measured using a filter trapping method.
Topics: Air Pollutants; Air; Nitrates; Lasers
PubMed: 36501859
DOI: 10.3390/s22239158 -
Optics Express Nov 2019We present an advanced optical-trapping method that is capable of trapping arbitrary shapes of transparent and absorbing particles in air. Two parabolic reflectors were...
We present an advanced optical-trapping method that is capable of trapping arbitrary shapes of transparent and absorbing particles in air. Two parabolic reflectors were used to reflect the inner and outer parts of a single hollow laser beam, respectively, to form two counter-propagating conical beams and bring them into a focal point for trapping. This novel design demonstrated high trapping efficiency and strong trapping robustness with a simple optical configuration. Instead of using expensive microscope objectives, the parabolic reflectors can not only achieved large numerical aperture (N.A.) focusing, but were also able to focus the beam far away from optical surfaces to minimize optics contamination. This design also offered a large free space for flexible integration with other measuring techniques, such as optical-trapping Raman spectroscopy, for on-line single particle characterization.
PubMed: 31878380
DOI: 10.1364/OE.27.033061 -
Internal Medicine (Tokyo, Japan) 2021Objective Bronchial thermoplasty (BT) is a bronchoscopic procedure for patients with severe asthma. Although it has been suggested that BT works by reducing airway...
Objective Bronchial thermoplasty (BT) is a bronchoscopic procedure for patients with severe asthma. Although it has been suggested that BT works by reducing airway smooth muscle, the detailed mechanism underlying its effects is still unknown. Methods We performed xenon ventilation computed tomography (Xe-CT) before each BT procedure and six weeks after the third treatment to assess the improvement in lung ventilation at each separate lung region. The air trapping index in each lobe was defined as the mean trapping value (0: none, 1: mild, 2: moderate, and 3: severe) of the included segments. Patients and Materials Four patients were included. Results Asthma symptoms were improved after BT. The comparison of the scores at baseline with those after the third treatment showed that the air trapping index was improved in both the treated and untreated regions. However, neither the pulmonary function nor the exhaled nitric oxide was improved. Conclusion Using Xe-CT, we successfully evaluated the air trapping in patients who underwent BT. The improvement in asthma symptoms by BT may be related to the amelioration of peripheral lung ventilation in both the treated and untreated regions.
Topics: Asthma; Bronchial Thermoplasty; Humans; Lung; Tomography, X-Ray Computed; Xenon
PubMed: 34193773
DOI: 10.2169/internalmedicine.6493-20 -
Scientific Reports Apr 2022In patients with chronic obstructive pulmonary disease (COPD), emphysema, airway disease, and extrapulmonary comorbidities may cause various symptoms and impair physical...
Associations of pulmonary and extrapulmonary computed tomographic manifestations with impaired physical activity in symptomatic patients with chronic obstructive pulmonary disease.
In patients with chronic obstructive pulmonary disease (COPD), emphysema, airway disease, and extrapulmonary comorbidities may cause various symptoms and impair physical activity. To investigate the relative associations of pulmonary and extrapulmonary manifestations with physical activity in symptomatic patients, this study enrolled 193 patients with COPD who underwent chest inspiratory/expiratory CT and completed COPD assessment test (CAT) and the Life-Space Assessment (LSA) questionnaires to evaluate symptom and physical activity. In symptomatic patients (CAT ≥ 10, n = 100), emphysema on inspiratory CT and air-trapping on expiratory CT were more severe and height-adjusted cross-sectional areas of pectoralis muscles (PM index) and adjacent subcutaneous adipose tissue (SAT index) on inspiratory CT were smaller in those with impaired physical activity (LSA < 60) than those without. In contrast, these findings were not observed in less symptomatic patients (CAT < 10). In multivariable analyses of the symptomatic patients, severe air-trapping and lower PM index and SAT index, but not CT-measured thoracic vertebrae bone density and coronary artery calcification, were associated with impaired physical activity. These suggest that increased air-trapping and decreased skeletal muscle and subcutaneous adipose tissue quantity are independently associated with impaired physical activity in symptomatic patients with COPD.
Topics: Exercise; Humans; Lung; Pulmonary Disease, Chronic Obstructive; Pulmonary Emphysema; Tomography, X-Ray Computed
PubMed: 35379884
DOI: 10.1038/s41598-022-09554-6 -
BMC Pulmonary Medicine Feb 2014Small airways are regarded as the elective anatomic site of obstruction in most chronic airway diseases. Expiratory computed tomography (CT) is increasingly used to...
BACKGROUND
Small airways are regarded as the elective anatomic site of obstruction in most chronic airway diseases. Expiratory computed tomography (CT) is increasingly used to assess obstruction at this level but there is no consensus regarding the best quantification method. We aimed to evaluate software-assisted CT quantification of air trapping for assessing small airway obstruction and determine which CT criteria better predict small airway obstruction on single breath nitrogen test (SBNT).
METHODS
Eighty-nine healthy volunteers age from 60 to 90 years old, underwent spirometrically-gated inspiratory (I) and expiratory (E) CT and pulmonary function tests (PFTs) using SBNT, performed on the same day. Air trapping was estimated using dedicated software measuring on inspiratory and expiratory CT low attenuation area (LAA) lung proportion and mean lung density (MLD). CT indexes were compared to SBNT results using the Spearman correlation coefficient and hierarchical dendrogram analysis. In addition, receiver operating characteristic (ROC) curve analysis was performed to determine the optimal CT air-trapping criterion.
RESULTS
43 of 89 subjects (48,3%) had dN2 value above the threshold defining small airway obstruction (i.e. 2.5% N2/l). Expiratory to inspiratory MLD ratio (r = 0.40) and LAA for the range -850 -1024 HU (r = 0.29) and for the range -850 -910 HU (r = 0.37) were positively correlated with SBNT results. E/I MLD was the most suitable criterion for its expression. Expiratory to inspiratory MLD ratio (E/I MLD) showed the highest AUC value (0.733) for small airway obstruction assessment.
CONCLUSION
Among all CT criteria, all correlating with small airway obstruction on SBNT, E/I MLD was the most suitable criterion for its expression in asymptomatic subjects with mild small airway obstruction
TRIAL REGISTRATION
Registered at Clinicaltrials.gov, identifier: NCT01230879.
Topics: Aged; Aged, 80 and over; Asthma; Breath Tests; Cross-Sectional Studies; Exhalation; Humans; Middle Aged; Prospective Studies; Pulmonary Disease, Chronic Obstructive; Reproducibility of Results; Respiratory Function Tests; Software; Tomography, X-Ray Computed
PubMed: 24581147
DOI: 10.1186/1471-2466-14-29 -
Scientific Reports May 2022We evaluated pulmonary sequelae in COVID-19 survivors by quantitative inspiratory-expiratory chest CT (QCT) and explored abnormal pulmonary diffusion risk factors at the...
We evaluated pulmonary sequelae in COVID-19 survivors by quantitative inspiratory-expiratory chest CT (QCT) and explored abnormal pulmonary diffusion risk factors at the 6-month follow-up. This retrospective study enrolled 205 COVID-19 survivors with baseline CT data and QCT scans at 6-month follow-up. Patients without follow-up pulmonary function tests were excluded. All subjects were divided into group 1 (carbon monoxide diffusion capacity [DL] < 80% predicted, n = 88) and group 2 (DL ≥ 80% predicted, n = 117). Clinical characteristics and lung radiological changes were recorded. Semiquantitative total CT score (0-25) was calculated by adding five lobes scores (0-5) according to the range of lesion involvement (0: no involvement; 1: < 5%; 2: 5-25%; 3: 26-50%; 4: 51-75%; 5: > 75%). Data was analyzed by two-sample t-test, Spearman test, etc. 29% survivors showed air trapping by follow-up QCT. Semiquantitative CT score and QCT parameter of air trapping in group 1 were significantly greater than group 2 (p < 0.001). Decreased DL was negatively correlated with the follow-up CT score for ground-glass opacity (r = - 0.246, p = 0.003), reticulation (r = - 0.206, p = 0.002), air trapping (r = - 0.220, p = 0.002) and relative lung volume changes (r = - 0.265, p = 0.001). COVID-19 survivors with lung diffusion deficits at 6-month follow-up tended to develop air trapping, possibly due to small-airway impairment.
Topics: COVID-19; Follow-Up Studies; Humans; Lung; Retrospective Studies; Survivors; Tomography, X-Ray Computed
PubMed: 35513692
DOI: 10.1038/s41598-022-11237-1 -
The European Respiratory Journal Aug 2013Cystic fibrosis (CF) is primarily characterised by bronchiectasis and trapped air on chest computed tomography (CT). The revised Cystic Fibrosis Questionnaire...
Cystic fibrosis (CF) is primarily characterised by bronchiectasis and trapped air on chest computed tomography (CT). The revised Cystic Fibrosis Questionnaire respiratory symptoms scale (CFQ-R RSS) measures health-related quality of life. To validate bronchiectasis, trapped air and CFQ-R RSS as outcome measures, we investigated correlations and predictive values for pulmonary exacerbations. CF patients (aged 6-20 years) underwent CT, CFQ-R RSS and 1-year follow-up. Bronchiectasis and trapped air were scored using the CF-CT scoring system. Correlation coefficients and backward multivariate modelling were used to identify predictors of pulmonary exacerbations. 40 children and 32 adolescents were included. CF-CT bronchiectasis (r = -0.38, p<0.001) and CF-CT trapped air (r = -0.35, p = 0.003) correlated with CFQ-R RSS. Pulmonary exacerbations were associated with: bronchiectasis (rate ratio 1.10, 95% CI 1.02-1.19; p = 0.009), trapped air (rate ratio 1.02, 95% CI 1.00-1.05; p = 0.034) and CFQ-R RSS (rate ratio 0.95, 95% CI 0.91-0.98; p = 0.002). The CFQ-R RSS was an independent predictor of pulmonary exacerbations (rate ratio 0.96, 95% CI 0.94-0.97; p<0.001). Bronchiectasis, trapped air and CFQ-R RSS were associated with pulmonary exacerbations. The CFQ-R RSS was an independent predictor. This study further validated bronchiectasis, trapped air and CFQ-R RSS as outcome measures in CF.
Topics: Adolescent; Air; Bronchiectasis; Child; Cystic Fibrosis; Female; Humans; Lung; Male; Multivariate Analysis; Mutation; Observer Variation; Quality of Life; Retrospective Studies; Surveys and Questionnaires; Tomography, X-Ray Computed; Treatment Outcome; Young Adult
PubMed: 23314900
DOI: 10.1183/09031936.00137612 -
Physiological Measurement May 2018Electrical impedance tomography (EIT) has been shown to be a viable non-invasive, bedside imaging modality to monitor lung function. This paper introduces a method for...
OBJECTIVE
Electrical impedance tomography (EIT) has been shown to be a viable non-invasive, bedside imaging modality to monitor lung function. This paper introduces a method for identifying regions of air trapping from EIT data collected during tidal breathing and breath-holding maneuvers.
APPROACH
Ventilation-perfusion index maps are computed from dynamic EIT images. These maps are then used to identify regions of air trapping in the area of the lung as regions that are poorly ventilated but well perfused throughout the breathing and cardiac cycles. These EIT-identified regions are then compared with independently identified regions of low attenuation, or air trapping, on chest CT. Results of this method are demonstrated in two children with cystic fibrosis and on a healthy control subject.
MAIN RESULTS
In both CF children, the EIT-identified regions of air trapping matched the regions indicated from the chest CT. The EIT-based method is only validated with CT scans within 4 cm of the chest cross-section defined by the electrode plane.
SIGNIFICANCE
The results indicate the potential use of EIT-derived ventilation-perfusion index maps as a non-invasive method for identifying regions of air trapping.
Topics: Air; Child; Cystic Fibrosis; Electric Impedance; Female; Humans; Image Processing, Computer-Assisted; Male; Respiration; Tomography
PubMed: 29726838
DOI: 10.1088/1361-6579/aac295 -
Thorax Feb 2019Abnormal lung volumes that reflect air trapping are common in COPD. However, their significance in smokers with preserved spirometry (normal FEV to FVC ratio) is unclear.
BACKGROUND
Abnormal lung volumes that reflect air trapping are common in COPD. However, their significance in smokers with preserved spirometry (normal FEV to FVC ratio) is unclear.
METHODS
Using the Veterans Administration Informatics and Computing Infrastructure database, we identified 7479 patients at risk for COPD (ever smokers >40 years of age without restrictive lung disease) who had preserved spirometry and concomitant lung volume measurements, and examined their subsequent health records for clinical diagnoses of COPD, healthcare utilisation, follow-up spirometry and mortality.
RESULTS
Air trapping was prevalent, with 31% of patients having residual volume to total lung capacity ratio (RV:TLC) greater than the upper limit of normal (ULN). RV:TLC varied widely from 14% to 77% (51% to 204% of predicted) across the normal ranges of FEV:FVC and FEV. Patients with RV:TLC greater than the ULN were more likely to receive subsequent clinical diagnoses of COPD (HR (95% CI)=1.55 (1.42 to 1.70), p<0.001) and had higher all-cause mortality (HR (95% CI)=1.41 (1.29 to 1.54), p<0.001). They had higher rates of respiratory medication prescriptions and hospital and intensive care unit admissions. Other air trapping and static hyperinflation indices showed similar associations with health outcomes. Additionally, high-normal RV:TLC was associated with intermediate adverse health outcomes compared with low-normal and abnormal RV:TLC. Abnormal RV:TLC predicted higher likelihood of progression to spirometric COPD (OR (95% CI)=1.30 (1.03 to 1.65), p=0.027).
CONCLUSION
In this study of the Veterans Affairs electronic health records, air trapping was common in smokers with preserved spirometry and predicted adverse respiratory outcomes and progression to overt COPD.
Topics: Adult; Aged; Databases, Factual; Disease Progression; Female; Humans; Lung; Male; Middle Aged; Patient Acceptance of Health Care; Pulmonary Disease, Chronic Obstructive; Retrospective Studies; Smokers; Spirometry; Survival Rate; Veterans
PubMed: 30030304
DOI: 10.1136/thoraxjnl-2018-211881 -
Balkan Medical Journal Apr 2017Several recent studies have suggested that 1 minus-forced expiratory volume expired in 3 seconds / forced vital capacity (1-FEV3/FVC) may be an indicator of distal...
BACKGROUND
Several recent studies have suggested that 1 minus-forced expiratory volume expired in 3 seconds / forced vital capacity (1-FEV3/FVC) may be an indicator of distal airway obstruction and a promising measure to evaluate small airways dysfunction.
AIMS
To investigate the associations of 1-FEV3/FVC with the spirometric measures and lung volumes that assess small airways dysfunction and reflects hyperinflation and air trapping.
STUDY DESIGN
Retrospective cross-sectional study.
METHODS
Retrospective assessment of a total of 1110 cases who underwent body plethysmographic lung volume estimations between a time span from 2005 to 2012. Patients were assigned into two groups: firstly by FEV1/FVC (FEV1/FVC <70% vs. FEV1/FVC ≥70%); secondly by FEV3/FVC < lower limits of normal (LLN) (FEV3/FVC < LLN vs. FEV3/FVC ≥ LLN). Spirometric indices and lung volumes measured by whole-body plethysmography were compared in groups. Also the correlation of spirometric indices with measured lung volumes were assessed in the whole-study population and in subgroups stratified according to FEV1/FVC and FEV3/FVC.
RESULTS
Six hundred seven (54.7%) were male and 503 (45.3%) were female, with a mean age of 52.5±15.6 years. Mean FEV3/FVC and 1-FEV3/FVC were 87.05%, 12.95%, respectively. The mean 1-FEV3/FVC was 4.9% in the FEV1/FVC ≥70% group (n=644) vs. 24.1% in the FEV1/FVC <70% group (n=466). A positive correlation was found between 1-FEV3/FVC and residual volume (r=0.70; p<0.0001), functional residual capacity-pleth (r=0.61; p<0.0001), and total lung capacity (r=0.47; p<0.0001). 1-FEV3/FVC was negatively correlated with forced expiratory flow25-75 (r=-0.84; p<0.0001). The upper limit of 95% confidence interval for 1-FEV3/FVC was 13.7%. 1-FEV3/FVC showed significant correlations with parameters of air trapping and hyperinflation measured by whole-body plethysmography. Importantly, these correlations were higher in study participants with FEV1/FVC <70% or FEV3/FVC < LLN compared to those with FEV1/FVC ≥70% or FEV3/FVC ≥ LLN, respectively.
CONCLUSION
1-FEV3/FVC can be easily calculated from routine spirometric measurements. 1-FEV3/FVC is a promising marker of air trapping and hyperinflation. We suggest that 1-FEV3/FVC is complementary to FEV1/FVC and recommend clinicians to routinely report and evaluate together with FEV1/FVC during spirometry.
Topics: Adult; Aged; Cross-Sectional Studies; Female; Forced Expiratory Volume; Humans; Lung; Lung Volume Measurements; Male; Middle Aged; Respiratory Function Tests; Retrospective Studies; Severity of Illness Index; Spirometry; Statistics, Nonparametric; Vital Capacity; Weights and Measures
PubMed: 28418337
DOI: 10.4274/balkanmedj.2015.0857