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Physiological Reports Feb 2022Navy divers tend to have large lungs and low expiratory flow rates in the terminal portion of a spirogram. We examined Finnish Navy divers for the presence of air...
Navy divers tend to have large lungs and low expiratory flow rates in the terminal portion of a spirogram. We examined Finnish Navy divers for the presence of air trapping, airway obstruction, and functional airway compression, and their association with lung volumes. Divers (n = 57) and non-diving men (n = 10) underwent a variety of pulmonary function tests. The amount of trapped air was calculated as the subtraction of the total lung capacity (TLC) measured in a single-breath helium dilution test from the TLC in body plethysmography (TLCb). Mean vital capacity (VC) was 6.4 L in the divers versus 5.8 L in the controls (p = 0.006) and TLCb 8.9 L in the divers versus 8.1 L in the controls (p = 0.002). No difference existed between them in the amount of trapped air. However, we found break points in a linear regression model (Davies test) between trapped air and several pulmonary parameters. Those individuals above the break points had lower ratio of forced expiratory volume in first second to forced vital capacity, lower resistance of airways, and higher reactance than those below the break points. In conclusion, navy divers had larger lungs than controls. Large lung volumes (VC >7.31 L or >122% of predicted value) were associated with air trapping. Furthermore, large volumes of air trapping (>1.1 L) were associated with increased residual volume (RV) and RV/TLCb. Despite no concurrent obstruction, functional airway compression, or reduced diffusing capacity, this slowly ventilated trapped air might remain disadvantageous for divers.
Topics: Forced Expiratory Volume; Humans; Lung; Male; Respiratory Function Tests; Total Lung Capacity; Vital Capacity
PubMed: 35212176
DOI: 10.14814/phy2.15153 -
The European Respiratory Journal Jan 2017We investigated regional air trapping on computed tomography in current smokers with normal spirometry. It was hypothesised that presence of regional air trapping may...
We investigated regional air trapping on computed tomography in current smokers with normal spirometry. It was hypothesised that presence of regional air trapping may indicate a specific manifestation of smoking-related changes.40 current smokers, 40 patients with chronic obstructive pulmonary disease (COPD), and 40 healthy never- smokers underwent computed tomography scans. Regional air trapping was assessed on end-expiratory scans and emphysema, micronodules and bronchial wall thickening on inspiratory scans. The ratio of expiratory and inspiratory mean lung attenuation (E/I) was calculated as a measure of static (fixed) air trapping.Regional air trapping was present in 63% of current smokers, in 45% of never smokers and in 8% of COPD patients (p<0.001). Current smokers with and without regional air trapping had E/I ratio of 0.81 and 0.91, respectively (p<0.001). Forced expiratory volume in 1 s (FEV) was significantly higher and emphysema less frequent in current smokers with regional air trapping.Current smokers with regional air trapping had higher FEV and less emphysema on computed tomography. In contrast, current smokers without regional air trapping resembled COPD. Our results highlight heterogeneity among smokers with normal spirometry and may contribute to early detection of smoking related structural changes in the lungs.
Topics: Aged; Air; Bronchoalveolar Lavage Fluid; Bronchoscopy; Case-Control Studies; Female; Forced Expiratory Volume; Functional Residual Capacity; Humans; Linear Models; Lung; Male; Middle Aged; Multivariate Analysis; Observer Variation; Pulmonary Disease, Chronic Obstructive; Pulmonary Emphysema; Smoking; Spirometry; Sweden; Tomography, X-Ray Computed
PubMed: 28122862
DOI: 10.1183/13993003.00345-2016 -
Journal of Glaucoma Dec 2018Accurate gonioscopy is necessary for the diagnosis and the treatment of glaucoma. The "gold standard" for indirect gonioscopy has been the Goldmann 3-mirror lens,...
PURPOSE
Accurate gonioscopy is necessary for the diagnosis and the treatment of glaucoma. The "gold standard" for indirect gonioscopy has been the Goldmann 3-mirror lens, requires an optical coupling agent (methylcellulose) between the cornea and under the surface of the goniolens. The design of an ideal lens would not only eliminate the need for gel, but could at the same time solve the problems associated with the trapping of an air bubble under the lens.
MATERIALS AND METHODS
This investigation involved a prototype 2-mirror goniolens with a radius of curvature of 8.4 mm and a 16 mm diameter area of corneal contact. A total of, 69 consecutive patients had bilateral keratometer measurements made. The prototype 2-mirror lens was applied to the anesthetized eye. The results of this examination were tabulated by one of the authors (F.M.K.); A=good fit without trapping of air, B=good fit but trapped bubble of air which could be expelled by the patient turning their eye towards the bubble, and C=total failure to expel the trapped bubble of air. Finally, if there were wrinkles in Descemet's membrane, this was recorded.
RESULTS
A total of 64 patients were evaluated with a prototype 2-mirror lens. In total, 54/64 (84.38%) of eyes were successfully evaluated without trapping of an air bubble.
CONCLUSION
Our stated goal of eliminating the need for gel as a coupling agent without trapping of an air bubble was successful in 54/64 eyes (84.38%). Our findings could spur development of newer bubble-free goniolenses for procedures such as laser trabeculoplasty.
Topics: Air; Descemet Membrane; Equipment Design; Female; Glaucoma, Open-Angle; Gonioscopy; Humans; Intraocular Pressure; Male; Microbubbles; Middle Aged; Ocular Hypertension
PubMed: 30161075
DOI: 10.1097/IJG.0000000000001067 -
Langmuir : the ACS Journal of Surfaces... Dec 2006The occurrence of air-trapping inside poly-eta-caprolactone nanopits was investigated by measuring the contact angles of water droplets on a set of defined...
The occurrence of air-trapping inside poly-eta-caprolactone nanopits was investigated by measuring the contact angles of water droplets on a set of defined nanotopographies. It is shown that the advancing angles follow the Cassie-Baxter theory, thus revealing the presence of air bubbles inside the biodegradable nanopatterns. The importance of these observations for the definition of hydrophilicity/hydrophobicity and in the context of in vitro cell behavior is discussed.
Topics: Absorption; Air; Biocompatible Materials; Hydrophobic and Hydrophilic Interactions; Nanoparticles; Polyesters
PubMed: 17154608
DOI: 10.1021/la061611t -
PloS One 2021Radiologic evidence of air trapping (AT) on expiratory computed tomography (CT) scans is associated with early pulmonary dysfunction in patients with cystic fibrosis...
BACKGROUND
Radiologic evidence of air trapping (AT) on expiratory computed tomography (CT) scans is associated with early pulmonary dysfunction in patients with cystic fibrosis (CF). However, standard techniques for quantitative assessment of AT are highly variable, resulting in limited efficacy for monitoring disease progression.
OBJECTIVE
To investigate the effectiveness of a convolutional neural network (CNN) model for quantifying and monitoring AT, and to compare it with other quantitative AT measures obtained from threshold-based techniques.
MATERIALS AND METHODS
Paired volumetric whole lung inspiratory and expiratory CT scans were obtained at four time points (0, 3, 12 and 24 months) on 36 subjects with mild CF lung disease. A densely connected CNN (DN) was trained using AT segmentation maps generated from a personalized threshold-based method (PTM). Quantitative AT (QAT) values, presented as the relative volume of AT over the lungs, from the DN approach were compared to QAT values from the PTM method. Radiographic assessment, spirometric measures, and clinical scores were correlated to the DN QAT values using a linear mixed effects model.
RESULTS
QAT values from the DN were found to increase from 8.65% ± 1.38% to 21.38% ± 1.82%, respectively, over a two-year period. Comparison of CNN model results to intensity-based measures demonstrated a systematic drop in the Dice coefficient over time (decreased from 0.86 ± 0.03 to 0.45 ± 0.04). The trends observed in DN QAT values were consistent with clinical scores for AT, bronchiectasis, and mucus plugging. In addition, the DN approach was found to be less susceptible to variations in expiratory deflation levels than the threshold-based approach.
CONCLUSION
The CNN model effectively delineated AT on expiratory CT scans, which provides an automated and objective approach for assessing and monitoring AT in CF patients.
Topics: Air; Child; Deep Learning; Exhalation; Female; Humans; Male; Neural Networks, Computer; Regression Analysis; Respiratory Function Tests; Tomography, X-Ray Computed
PubMed: 33760861
DOI: 10.1371/journal.pone.0248902 -
Journal of Computer Assisted Tomography 1999The purpose of our study was to correlate the extent of air trapping on expiratory CT scans with results of pulmonary function tests (PFTs) in a large group of patients... (Comparative Study)
Comparative Study
PURPOSE
The purpose of our study was to correlate the extent of air trapping on expiratory CT scans with results of pulmonary function tests (PFTs) in a large group of patients with primary Sjögren syndrome and to determine whether these techniques may be complementary in assessing small airways obstruction.
METHOD
Thirty-four nonsmoking patients with proven primary Sjögren syndrome and 10 healthy nonsmokers underwent paired inspiratory-expiratory thin section CT and PFTs. Expiratory scans were scored for the presence and extent of areas of air trapping. Extent of air trapping was assessed visually and given a score. The functional significance of the extent of air trapping was evaluated in both groups and then correlated with the results of PFTs.
RESULTS
Bronchiolar abnormalities were seen in 11 (32%) of 34 patients with primary Sjögren syndrome. On the expiratory CT scans, a mosaic pattern of lung attenuation was identified in 17 patients. Air trapping was found in 44 of 204 lobar observations on the expiratory scans. The median point scale score at end-expiration was 3.6 (20%, Grade 1), ranging from 1 (5.5%, Grade 1) to 9 (50%, Grade 2). The mean total score of air trapping was more prevalent in lower (46/68) lobes (22.4%) than in upper (22/136) lobes (5.3%) (p < 0.001). PFTs were normal in the primary Sjögren syndrome patients as well as the healthy subjects. Air trapping was found more frequently in patients with primary Sjögren syndrome than in the healthy group. Only during exhalation was there evidence of minimal lobular-sized areas or air trapping (Grade 1) in three of the healthy subjects. We did not find any correlation between air trapping and PFTs including the forced expiratory flow rate between 25 and 75% of the forced vital capacity (FEF25-75).
CONCLUSION
Expiratory high resolution CT revealed the extent of bronchiolar disease in patients with primary Sjögren syndrome. We also found that the extent of air trapping did not correlate with PFTs, which suggests the existence of a subclinical bronchiolar inflammatory process that may precede detectable abnormalities in lung function tests.
Topics: Adult; Aged; Aged, 80 and over; Air; Female; Humans; Male; Middle Aged; Observer Variation; Prospective Studies; Radiography, Thoracic; Reference Values; Regression Analysis; Respiratory Function Tests; Sjogren's Syndrome; Statistics, Nonparametric; Tomography, X-Ray Computed
PubMed: 10096321
DOI: 10.1097/00004728-199903000-00002 -
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 -
Radiology Dec 2003To evaluate the intrapatient reproducibility of the extent and anatomic distribution of air trapping at sequential expiratory thin-section computed tomographic (CT)...
PURPOSE
To evaluate the intrapatient reproducibility of the extent and anatomic distribution of air trapping at sequential expiratory thin-section computed tomographic (CT) examinations in heart-lung transplant recipients.
MATERIALS AND METHODS
Nineteen heart-lung transplant recipients (eight with and 11 without bronchiolitis obliterans syndrome [BOS]) underwent three expiratory CT examinations within 1 hour. Residual volumes were measured at CT. Anatomic distribution and extent of air trapping were scored by two observers at two independent readings, and the reproducibility of observations was calculated for each feature. CT examination results were compared by using an analysis of variance that took into account interobserver and BOS and non-BOS effects. The Spearman rank correlation coefficient was calculated to test the association between variability of residual volumes and variability of the extent of air trapping.
RESULTS
Residual volumes did not significantly differ between the three CT examinations (P =.556). Reproducibility values for findings of anatomic distribution of air trapping ranged from 84% to 95%, with a tendency toward improved reproducibility in patients without BOS. Mean reproducibility values for the extent of air trapping ranged from 97.1% to 97.7%, and no substantial difference in these values between patients with and those without BOS was observed. The Spearman rank coefficient for the correlation between variability of residual volumes and variability of extent of air trapping ranged from 0.382 to 0.568 (P =.105-.016). No interobserver effect was detected (P =.944).
CONCLUSION
Anatomic distribution and extent are reproducible characteristics of air trapping. No substantial variability of air trapping occurs in functionally stable heart-lung transplant recipients.
Topics: Adult; Air; Bronchiolitis Obliterans; Exhalation; Female; Heart-Lung Transplantation; Humans; Male; Middle Aged; Observer Variation; Reproducibility of Results; Respiratory Function Tests; Tomography, X-Ray Computed
PubMed: 14657310
DOI: 10.1148/radiol.2293020827 -
Journal of Chromatography. A Jul 2000The use of sorbents in trapping volatile organic compounds in air for subsequent analysis is reviewed. Sorbents are classified in accordance with the mechanism used to... (Review)
Review
The use of sorbents in trapping volatile organic compounds in air for subsequent analysis is reviewed. Sorbents are classified in accordance with the mechanism used to recover the trapped compounds, either solvent or thermal desorption. The use of sorbents is contrasted with other sampling procedures, such as collecting whole air samples using canisters. New developments such as solid-phase microextraction are described. In particular, emphasis is placed on a holistic approach to sampling and analysis, and communication is encouraged between those who take samples in the field, and those who perform the analysis.
Topics: Adsorption; Air; Organic Chemicals; Reproducibility of Results; Volatilization
PubMed: 10941671
DOI: 10.1016/s0021-9673(00)00363-0 -
Micromachines Dec 2017Salvinia leaves represent an extraordinary example of how nature found a strategy for the long term retainment of air, and thus oxygen, on a surface, the so-called...
Salvinia leaves represent an extraordinary example of how nature found a strategy for the long term retainment of air, and thus oxygen, on a surface, the so-called 'Salvinia effect', thanks to the peculiar three-dimensional and hierarchical shape of the hairs covering the leaves. Here, starting from the natural model, we have microfabricated hairs inspired by those present on the leaves, by means of direct laser lithography. Artificial hairs, like their natural counterpart, are composed of a stalk and a crown-like head, and have been reproduced in the microscale since this ensures, if using a proper design, an air-retaining behavior even if the bulk structural material is hydrophilic. We have investigated the capability of air retainment inside the heads of the hairs that can last up to 100 h, demonstrating the stability of the phenomenon. For a given dimension of the head, the greater the number of filaments, the greater the amount of air that can be trapped inside the heads since the increase in the number of solid⁻air interfaces able to pin the liquid phase. For this reason, such type of pattern could be used for the fabrication of surfaces for controlled gas retainment and gas release in liquid phases. The range of applications would be quite large, including industrial, medical, and biological fields.
PubMed: 30400556
DOI: 10.3390/mi8120366