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PloS One 2021Expiratory flow limitation is a key characteristic in obstructive pulmonary diseases. To study abnormal lung mechanics isolated from heterogeneities of obstructive...
Expiratory flow limitation is a key characteristic in obstructive pulmonary diseases. To study abnormal lung mechanics isolated from heterogeneities of obstructive disease, we measured pulmonary function in healthy adults with expiratory loading. Thirty-seven volunteers (25±5 yr) completed spirometry and body plethysmography under control and threshold expiratory loading of 7, 11 cmH2O, and a subset at 20 cmH2O (n = 11). We analyzed the shape of the flow-volume relationship with rectangular area ratio (RAR; Ma et al., Respir Med 2010). Airway resistance was increased (p<0.0001) with 7 and 11 cmH2O loading vs control (9.20±1.02 and 11.76±1.68 vs. 2.53± 0.80 cmH2O/L/s). RAR was reduced (p = 0.0319) in loading vs control (0.45±0.07 and 0.47±0.09L vs. 0.48±0.08). FEV1 was reduced (p<0.0001) in loading vs control (3.24±0.81 and 3.23±0.80 vs. 4.04±1.05 L). FVC was reduced (p<0.0001) in loading vs control (4.11±1.01 and 4.14±1.03 vs. 5.03±1.34 L). Peak expiratory flow (PEF) was reduced (p<0.0001) in loading vs control (6.03±1.67 and 6.02±1.84 vs. 8.50±2.81 L/s). FEV1/FVC (p<0.0068) was not clinically significant and FRC (p = 0.4) was not different in loading vs control. Supra-physiologic loading at 20 cmH2O did not result in further limitation. Expiratory loading reduced FEV1, FVC, PEF, but there were no clinically meaningful differences in FEV1/FVC, FRC, or RAR. Imposed expiratory loading likely leads to high airway pressures that resist dynamic airway compression. Thus, a concave expiratory flow-volume relationship was consistently absent-a key limitation for model comparison with pulmonary function in COPD. Threshold loading may be a useful strategy to increase work of breathing or induce dynamic hyperinflation.
Topics: Adult; Airway Resistance; Exhalation; Humans; Lung; Plethysmography; Reference Values; Respiratory Function Tests; Spirometry; Young Adult
PubMed: 34115812
DOI: 10.1371/journal.pone.0252916 -
Journal of Physiological Anthropology Jan 2021Body composition (BC) influences respiratory system mechanics, provoking air flow limitation (AFL). The objective of this study was to determine the relationship of AFL...
BACKGROUND
Body composition (BC) influences respiratory system mechanics, provoking air flow limitation (AFL). The objective of this study was to determine the relationship of AFL in small- and medium-caliber airways with BC in young adults.
METHODS
Eighty-three individuals were recruited (40 men and 43 women). To determine AFL, the following measurements were taken: forced expiratory volume in the first second (FEV), forced expiratory flow between 25 and 75% (FEF), airway resistance (Raw), and specific airway resistance (sRaw). The measured BC variables were body mass index (BMI), body fat percentage (%BF), and fat-free mass (FFM). Binary logistical regression analysis was used to estimate the association between the AFL variables and %BF, BMI, and %FFM, adjusting for weight and gender.
RESULTS
Among men, a relationship was observed between Raw and %BF (r = 0.728; p < 0.0001) and sRaw and BMI (r = 0.617; p < 0.0001). Among women, significant relationships were reported between Raw and BMI (r = 0.615; p < 0.0001) and sRaw and BMI (r = 0.556; p < 0.0001). Among participants with a BMI over 30 kg/m, higher risks of increased Raw (OR = 26.8; p = 0.009) and sRaw (OR = 9.3; p = 0.002) were observed. Furthermore, higher %BF was associated with greater risks for increased Raw (OR = 14.04; p = 0.030) and sRaw (OR = 4.14; p = 0.028). In contrast, increased %FFM (OR = 0.14; p = 0.025) was a protective factor for lung function.
CONCLUSION
Increased %BF is associated with increased AFL in small-caliber airways. Furthermore, increased %FFM is associated with decreased risk for Raw and sRaw in women. Therefore, evidence indicates that increased %FFM is a protective factor for adequate lung function.
Topics: Adult; Airway Resistance; Body Composition; Body Mass Index; Cross-Sectional Studies; Female; Forced Expiratory Volume; Humans; Male; Obesity; Young Adult
PubMed: 33468239
DOI: 10.1186/s40101-021-00252-2 -
Einstein (Sao Paulo, Brazil) 2019To simulate different diameters of endotracheal tubes and to verify the fluid dynamics aspects by means of flow and resistance measurements.
OBJECTIVE
To simulate different diameters of endotracheal tubes and to verify the fluid dynamics aspects by means of flow and resistance measurements.
METHODS
Fluid dynamics software was used to calculate mean flow and airway resistance in endotracheal tube with a diameter of 6.0, 7.0, 7.5, 8.0, 9.0 and 10.0mm at normal body temperature and under constant pressure. The same measurements were taken in the fusion of the first 22cm of a 9.0mm endotracheal tube with 10.0mm diameter, and with the end part in 12cm of a 6.0mm endotracheal tube with 7.0mm diameter.
RESULTS
The fusion of the first 22cm of an endotracheal tube of 10.0mm diameter with the terminal part in 12cm of an endotracheal tube of 6.0mm diameter, preserving the total length of 34cm, generated average flow and airway resistance similar to that of a conventional 7.5mm endotracheal tube.
CONCLUSION
This simulation study demonstrates that a single-sized endotracheal tube may facilitate endotracheal intubation without causing increased airway resistance.
Topics: Airway Resistance; Computer Simulation; Equipment Design; Intubation, Intratracheal; Respiration, Artificial
PubMed: 31644676
DOI: 10.31744/einstein_journal/2020AO4805 -
Respiratory Care Sep 2017Tubing systems are an essential component of the ventilation circuit, connecting the ventilator to the patient's airways. Coaxial tubing systems incorporate the...
BACKGROUND
Tubing systems are an essential component of the ventilation circuit, connecting the ventilator to the patient's airways. Coaxial tubing systems incorporate the inspiratory tube within the lumen of the expiratory one. We hypothesized that by design, these tubing systems increase resistance to air flow compared with conventional ones.
METHODS
We investigated the flow-dependent pressure gradient across coaxial, conventional disposable, and conventional reusable tubing systems from 3 different manufacturers. Additionally, the additional work of breathing and perception of resistance during breathing through the different devices were determined in 18 healthy volunteers.
RESULTS
The pressure gradient across coaxial tubing systems was up to 6 times higher compared with conventional ones (1.90 ± 0.03 cm HO vs 0.34 ± 0.01 cm HO, < .001) and was higher during expiration compared with inspiration ( < .001). Additional work of breathing and perceived breathing resistance were highest in coaxial tubing systems, accordingly.
CONCLUSIONS
Our findings suggest that the use of coaxial tubing systems should be carefully considered with respect to their increased resistance.
Topics: Adult; Airway Resistance; Disposable Equipment; Equipment Design; Equipment Reuse; Female; Healthy Volunteers; Humans; Lung; Male; Pressure; Respiration, Artificial; Work of Breathing
PubMed: 28807989
DOI: 10.4187/respcare.05426 -
Respiratory Medicine Dec 2021Small airway dysfunction (SAD) is an early lesion of chronic respiratory disease that is best detected using impulse oscillometry (IOS). Few studies have investigated... (Observational Study)
Observational Study
BACKGROUND
Small airway dysfunction (SAD) is an early lesion of chronic respiratory disease that is best detected using impulse oscillometry (IOS). Few studies have investigated risk factors for IOS-defined SAD (IOS-SAD) in a large population. We aimed to explore the clinical features of and risk factors for IOS-SAD in a community-based population.
METHODS
We divided subjects into IOS-SAD and non-SAD groups based on a cutoff of >0.07 kPa/L/s in the difference between the resistance at 5 Hz versus the resistance at 20 Hz (R5-R20). All participants underwent spirometry, IOS, and completed a questionnaire; some participants underwent computed tomography (CT). We analyzed the risk factors for SAD based on binary logistic regression.
RESULTS
The total cohort comprised 1327 subjects. The prevalence of IOS-SAD was 32.9% (437/1327). Compared with the non-SAD group, the IOS-SAD group was older (64.0 ± 7.8 vs. 59.6 ± 7.8 years, p < 0.001), included less never-smokers (30.2% vs. 35.8%, p < 0.001), had greater airway resistance and worse lung function, indicated by a larger R5-R20 (0.15 ± 0.08 vs. 0.03 ± 0.02 kPa/L/s, p < 0.001) and smaller forced expiratory volume in 1 s to forced vital capacity after bronchodilation (60.2 ± 14.4% vs. 72.6 ± 10.0%, p < 0.001); on CT, the IOS-SAD group had higher prevalences of emphysema and gas trapping. Risk factors for SAD were older age, high BMI, smoking, childhood cough, and asthma.
CONCLUSION
Subjects with IOS-SAD had increased airway resistance and visible CT changes. Individuals with smoking exposure, advanced age, high BMI, childhood cough, and asthma were more prone to SAD.
CLINICAL TRIAL REGISTRATION
ChiCTR1900024643.
Topics: Age Factors; Airway Resistance; Asthma; Body Mass Index; Cough; Cross-Sectional Studies; Emphysema; Female; Humans; Male; Middle Aged; Oscillometry; Pulmonary Disease, Chronic Obstructive; Respiratory Function Tests; Risk Factors; Smoking
PubMed: 34784563
DOI: 10.1016/j.rmed.2021.106681 -
Tuberculosis and Respiratory Diseases Apr 2024: Bronchiectasis is a chronic respiratory disease that leads to airway inflammation, destruction, and airflow limitation, which reflects its severity. Impulse...
BACKGROUND
: Bronchiectasis is a chronic respiratory disease that leads to airway inflammation, destruction, and airflow limitation, which reflects its severity. Impulse oscillometry (IOS) is a non-invasive method that uses sound waves to estimate lung function and airway resistance. The aim of this study was to assess the usefulness of IOS in predicting the severity of bronchiectasis.
METHODS
: We retrospectively reviewed the IOS parameters and clinical characteristics in 145 patients diagnosed with bronchiectasis between March 2020 and May 2021. Disease severity was evaluated using the FACED score, and patients were divided into mild and moderate/severe groups.
RESULTS
: Forty-four patients (30.3%) were in the moderate/severe group, and 101 (69.7%) were in the mild group. Patients with moderate/severe bronchiectasis had a higher airway resistance at 5 Hz (R5), a higher difference between the resistance at 5 and 20 Hz (R5-R20), a higher resonant frequency (Fres), and a higher area of reactance (AX) than patients with mild bronchiectasis. R5 ≥0.43, resistance at 20 Hz (R20) ≥0.234, R5-R20 ≥28.3, AX ≥1.02, reactance at 5 Hz (X5) ≤-0.238, and Fres ≥20.88 revealed significant univariable relationships with bronchiectasis severity (p<0.05). Among these, only X5 ≤-0.238 exhibited a significant multivariable relationship with bronchiectasis severity (p=0.039). The receiver operating characteristic curve for predicting moderate- to-severe bronchiectasis of FACED score based on IOS parameters exhibited an area under the curve of 0.809.
CONCLUSION
: The IOS assessed by the disease severity of FACED score can effectively reflect airway resistance and elasticity in bronchiectasis patients and serve as valuable tools for predicting bronchiectasis severity.
PubMed: 38783483
DOI: 10.4046/trd.2023.0160 -
Journal of Applied Physiology... Apr 2021In the community setting, assessing spirometry in school-aged children is often limited by the unavailability of respirology technicians at the point-of-care. We...
In the community setting, assessing spirometry in school-aged children is often limited by the unavailability of respirology technicians at the point-of-care. We developed a new technique called the Rapid Expiratory Occlusion Method (REOM) that measures respiratory resistance during normal breathing, without specialized training. The aim was to examine the concordance between respiratory resistance measured with the REOM and respiratory resistance measured by oscillometry on the tremoflo. Children aged 6-17 yr, with or without asthma, received respiratory resistance testing on the tremoflo, then on the REOM. Three to five replicates with a coefficient of variation ≤15% were obtained on each instrument; the primary outcome was the concordance between the average respiratory resistance on the REOM and that measured at 5 Hz (R) on the tremoflo. Thirty-two children (11 girls; 21 boys) were enrolled with a mean age of 11.2 (range 6-17) yr; after excluding two children not meeting reproducibility criteria, 9 healthy controls, 15 controlled asthmatics, and 6 poorly controlled asthmatics were included. Resistance measured on the REOM showed a strong correlation with R measured on the tremoflo ( < 0.0001) with no significant differences on the Bland-Altman analyses. Children and their parents found the REOM easy to use and would consider for home use if recommended by their doctor. With the high concordance between resistance values measured on the REOM and that on the tremoflo combined with perceived ease of use, the REOM appears as a promising means for measuring lung function, thus supporting further testing of other psychometric properties. We have developed a novel version of the interrupter technique to measure respiratory resistance. The Rapid Expiratory Occlusion Method (REOM) is a small handheld device that measures respiratory resistance and demonstrates excellent correlation with airway oscillometry. With its ease of use, REOM may be promising for use in community practice, patient's homes, and, if paired with a telemedicine application, could enable the healthcare provider to monitor patients in their homes.
Topics: Airway Resistance; Child; Female; Humans; Lung; Male; Oscillometry; Reproducibility of Results; Respiratory Function Tests; Spirometry
PubMed: 33539262
DOI: 10.1152/japplphysiol.01072.2020 -
IL-22 and its receptors are increased in human and experimental COPD and contribute to pathogenesis.The European Respiratory Journal Jul 2019Chronic obstructive pulmonary disease (COPD) is the third leading cause of morbidity and death globally. The lack of effective treatments results from an incomplete...
Chronic obstructive pulmonary disease (COPD) is the third leading cause of morbidity and death globally. The lack of effective treatments results from an incomplete understanding of the underlying mechanisms driving COPD pathogenesis.Interleukin (IL)-22 has been implicated in airway inflammation and is increased in COPD patients. However, its roles in the pathogenesis of COPD is poorly understood. Here, we investigated the role of IL-22 in human COPD and in cigarette smoke (CS)-induced experimental COPD.IL-22 and IL-22 receptor mRNA expression and protein levels were increased in COPD patients compared to healthy smoking or non-smoking controls. IL-22 and IL-22 receptor levels were increased in the lungs of mice with experimental COPD compared to controls and the cellular source of IL-22 included CD4 T-helper cells, γδ T-cells, natural killer T-cells and group 3 innate lymphoid cells. CS-induced pulmonary neutrophils were reduced in IL-22-deficient ( ) mice. CS-induced airway remodelling and emphysema-like alveolar enlargement did not occur in mice. mice had improved lung function in terms of airway resistance, total lung capacity, inspiratory capacity, forced vital capacity and compliance.These data highlight important roles for IL-22 and its receptors in human COPD and CS-induced experimental COPD.
Topics: Airway Remodeling; Airway Resistance; Animals; Emphysema; Female; Humans; Immunity, Innate; Interleukins; Lymphocytes; Mice; Mice, Inbred C57BL; Mice, Knockout; Pulmonary Disease, Chronic Obstructive; Receptors, Interleukin; Smoke; Tobacco Products; Interleukin-22
PubMed: 31196943
DOI: 10.1183/13993003.00174-2018 -
Jornal Brasileiro de Pneumologia :... 2016Many patients with proportional reductions in FVC and FEV1 on spirometry show no reduction in TLC. The aim of this study was to evaluate the role that measuring lung...
OBJECTIVE:
Many patients with proportional reductions in FVC and FEV1 on spirometry show no reduction in TLC. The aim of this study was to evaluate the role that measuring lung volumes and airway resistance plays in the correct classification of patients with a possible restrictive pattern on spirometry.
METHODS:
This was a prospective study involving adults with reduced FVC and FEV1, as well as an FEV1/FV(C) ratio within the predicted range. Restrictive lung disease (RLD) was characterized by TLC below the 5th percentile, as determined by plethysmography. Obstructive lung disease (OLD) was characterized by high specific airway resistance, significant changes in post-bronchodilator FEV1, or an FEF25-75% < 50% of predicted, together with a high RV/TLC ratio. Nonspecific lung disease (NLD) was characterized by TLC within the predicted range and no obstruction. Combined lung disease (CLD) was characterized by reduced TLC and findings indicative of airflow obstruction. Clinical diagnoses were based on clinical suspicion, a respiratory questionnaire, and the review of tests of interest.
RESULTS:
We included 300 patients in the study, of whom 108 (36%) were diagnosed with RLD. In addition, 120 (40%) and 72 (24%) were diagnosed with OLD/CLD and NLD, respectively. Among the latter, 24 (33%) were clinically diagnosed with OLD. In this sample, 151 patients (50.3%) were obese, and obesity was associated with all patterns of lung disease.
CONCLUSIONS:
Measuring lung volumes and airway resistance is often necessary in order to provide an appropriate characterization of the pattern of lung disease in patients presenting with a spirometry pattern suggestive of restriction. Airflow obstruction is common in such cases.
OBJETIVO:
Muitos pacientes com redução proporcional de CVF e VEF1 na espirometria não têm CPT reduzida. O objetivo deste estudo foi avaliar o papel da medida dos volumes pulmonares e da resistência das vias aéreas para a classificação correta de pacientes com possível restrição à espirometria.
MÉTODOS:
Estudo prospectivo de adultos com CVF e VEF1 reduzidos e relação VEF1/CV(F) na faixa prevista. Distúrbio ventilatório restritivo (DVR) foi definido por CPT < 5º percentil por pletismografia. Distúrbio ventilatório obstrutivo (DVO) foi caracterizado por resistência específica de vias aéreas elevada, resposta significativa do VEF1 pós-broncodilatador e/ou um FEF25-75% < 50% do previsto associado a uma relação VR/CPT elevada. Distúrbio ventilatório inespecífico (DVI) foi caracterizado por CPT na faixa prevista e ausência de obstrução. Distúrbio ventilatório combinado (DVC) foi caracterizado por CPT reduzida e achados indicativos de obstrução ao fluxo aéreo. Os diagnósticos clínicos foram baseados em suspeita clínica, um questionário respiratório e revisão de exames de interesse.
RESULTADOS:
Foram incluídos 300 pacientes no estudo, dos quais 108 (36%) tiveram diagnóstico de DVR, enquanto 120 (40%) foram diagnosticados com DVO ou DVC e 72 (24%) com DVI. Destes últimos, 24 (33%) tinham diagnóstico clínico de DVO. Nesta amostra, 151 pacientes (50,3%) eram obesos, e isso se associou com todos os padrões de distúrbios funcionais.
CONCLUSÕES:
Medidas dos volumes pulmonares e da resistência das vias aéreas são frequentemente necessárias para a caracterização adequada do tipo de distúrbio funcional em casos com possível restrição à espirometria. A obstrução ao fluxo aéreo é comum nesses casos.
Topics: Adult; Aged; Airway Resistance; Female; Humans; Lung Diseases, Interstitial; Lung Diseases, Obstructive; Lung Volume Measurements; Male; Middle Aged; Obesity; Predictive Value of Tests; Prospective Studies; Respiratory Function Tests; Spirometry; Total Lung Capacity
PubMed: 27812633
DOI: 10.1590/S1806-37562016000000091 -
American Journal of Physiology. Lung... Jul 2019Airway narrowing due to hyperresponsiveness severely limits gas exchange in patients with asthma. Imaging studies in humans and animals have shown that...
Airway narrowing due to hyperresponsiveness severely limits gas exchange in patients with asthma. Imaging studies in humans and animals have shown that bronchoconstriction causes patchy patterns of ventilation defects throughout the lungs, and several computational models have predicted that these regions are due to constriction of smaller airways. However, these imaging approaches are often limited in their ability to capture dynamic changes in small airways, and the patterns of constriction are heterogeneous. To directly investigate regional variations in airway narrowing and the response to deep inspirations (DIs), we utilized tantalum dust and microfocal X-ray imaging of rat lungs to obtain dynamic images of airways in an intact animal model. Airway resistance was simultaneously measured using the flexiVent system. Custom-developed software was used to track changes in airway diameters up to (~0.3-3 mm). Changes in diameter during bronchoconstriction were then measured in response to methacholine (MCh) challenge. In contrast with the model predictions, we observed significantly greater percent constriction in larger airways in response to MCh challenge. Although there was a dose-dependent increase in total respiratory resistance with MCh, the percent change in airway diameters was similar for increasing doses. A single DI following MCh caused a significant reduction in resistance but did not cause a significant increase in airway diameters. Multiple DIs did, however, cause significant increases in airway diameters. These measurements allowed us to directly quantify dynamic changes in airways during bronchoconstriction and demonstrated greater constriction in larger airways.
Topics: Airway Resistance; Animals; Bronchial Provocation Tests; Bronchoconstriction; Bronchoconstrictor Agents; Dust; Inhalation; Lung; Methacholine Chloride; Rats; Tantalum; Tomography, X-Ray Computed
PubMed: 31017015
DOI: 10.1152/ajplung.00050.2019