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Indian Journal of Endocrinology and... 2023Obesity is known to induce lung function impairment. Previous studies of decline in lung function associated with obesity are well established.
BACKGROUND
Obesity is known to induce lung function impairment. Previous studies of decline in lung function associated with obesity are well established.
MATERIALS AND METHODS
In this cross-sectional study, to evaluate the effects of different obesity indices on lung mechanics, healthy subjects (males-23 and females-22) were recruited. Anthropometric parameters like body mass index (BMI), waist circumference (WC), hip circumference (HC) and neck circumference (NC) were measured and waist-hip ratio (WHR) was derived. Spirometry, impulse oscillometry (IOS) and fractional exhaled nitric oxide (FeNO) measurements were performed to assess lung function. Subgroups were divided and analysed.
RESULTS
In males, increased WHR is associated with increased total airway resistance (R). BMI correlates positively with R, R% predicted, resistance at 20 Hz (R) and R% predicted; likewise, WHR shows a positive correlation with R. In females, increased WHR has significantly higher R, R% predicted, R, R% predicted, area of reactance (Ax), resonant frequency (Fres) and decreased reactance at 5 Hz (X), reactance at 20 Hz (X), X% predicted. The female group with higher WC shows significantly increased R, R% predicted, R, R% predicted, Ax, Fres and lower fixed ratio of forced expiratory volume in 1 s (FEV)/forced vital capacity (FVC), X, X, X% predicted. The group with higher NC has a lower FEV/FVC ratio. WHR positively correlated with R% predicted and Fres while WC correlated positively with R, R% predicted, Ax and Fres; same way, NC with X% predicted.
CONCLUSION
Obesity/overweight causes significant changes in lung volumes, capacity and airway mechanics, Higher WC and WHR are associated with significant changes in lung mechanics, which are more prominent in females than in males. NC is not associated with changes in lung mechanics.
PubMed: 37292068
DOI: 10.4103/ijem.ijem_363_22 -
Respiratory Physiology & Neurobiology Nov 2021Cystic fibrosis (CF) is characterized by small airway disease; but central airways may also be affected. We hypothesized that airway resistance estimated from...
Cystic fibrosis (CF) is characterized by small airway disease; but central airways may also be affected. We hypothesized that airway resistance estimated from computational fluid dynamic (CFD) methodology in infants with CF was higher than controls and that early airway inflammation in infants with CF is associated with airway resistance. Central airway models with a median of 51 bronchial outlets per model (interquartile range 46,56) were created from chest computed tomography scans of 18 infants with CF and 7 controls. Steady state airflow into the trachea was simulated to estimate central airway resistance in each model. Airway resistance was increased in the full airway models of infants with CF versus controls and in models trimmed to 33 bronchi. Airway resistance was associated with markers of inflammation in bronchoalveolar lavage fluid obtained approximately 8 months earlier but not with markers obtained at the same time. In conclusion, airway resistance estimated by CFD modeling is increased in infants with CF compared to controls and may be related to early airway inflammation.
Topics: Airway Resistance; Computer Simulation; Cystic Fibrosis; Humans; Hydrodynamics; Infant; Models, Biological; Pneumonia; Tomography, X-Ray Computed
PubMed: 34157384
DOI: 10.1016/j.resp.2021.103722 -
Journal of Mathematical Biology Oct 2022All schoolchildren know how often they breathe, but even experts don't know exactly why. The aim of this publication is to develop a model of the resting spontaneous...
All schoolchildren know how often they breathe, but even experts don't know exactly why. The aim of this publication is to develop a model of the resting spontaneous breathing rate using physiological, physical and mathematical methods with the aid of the principle that evolution pushes physiology in a direction that is as economical as possible. The respiratory rate then follows from an equation with the parameters [Formula: see text]-production rate of the organism, resistance, static compliance and dead space of the lungs, the inspiration duration: expiration duration - ratio and the end-expiratory [Formula: see text] fraction. The derivation requires exclusively secondary school mathematics. Using the example of an adult human or a newborn child, data from the literature then result in normal values for their breathing rate at rest. The reason for the higher respiratory rate of a newborn human compared to an adult is the relatively high [Formula: see text]-production rate together with the comparatively low compliance of the lungs. A side result is the fact that the common alveolar pressure throughout the lungs and the common time constant is a consequence of the economical principle as well. Since the above parameters are not human-specific, there is no reason to assume that the above equation could not also be applicable to many animals breathing through lungs within a thorax, especially mammals. Not only physiology and biology, but also medicine, could benefit: Applicability is being discussed in pulmonary function diagnostics, including pathophysiology. However, the present publication only claims to be a theoretical concept of the spontaneous quiet breathing rate. In the absence of comparable animal data, this publication is intended to encourage further scientific tests.
Topics: Humans; Adult; Animals; Infant, Newborn; Child; Respiratory Rate; Lung; Mammals
PubMed: 36282355
DOI: 10.1007/s00285-022-01790-8 -
Ear, Nose, & Throat Journal Oct 2023The tracheoesophageal fistula (TEF) is an abnormal flow between the esophagus and the trachea. Most patients with TEF experience severe symptoms. Asymptomatic TEF is...
The tracheoesophageal fistula (TEF) is an abnormal flow between the esophagus and the trachea. Most patients with TEF experience severe symptoms. Asymptomatic TEF is rare. In this case report, a 47-year-old woman planned to undergo orthopedic surgery under general anesthesia. She had no symptoms related to TEF, and the preoperative chest computed tomography was also normal. However, there was significant airway resistance after induction. Using a fiber bronchoscope, a TEF was discovered. The TEF found after anesthesia due to high airway pressure is unusual, and the outcome and treatment of these patients need to be further discussed.
PubMed: 37837180
DOI: 10.1177/01455613231200810 -
Intensive Care Medicine Experimental Jul 2019The biological effects and physiological consequences of hypercapnia are increasingly understood. The literature on hypercapnia is confusing, and at times contradictory.... (Review)
Review
The biological effects and physiological consequences of hypercapnia are increasingly understood. The literature on hypercapnia is confusing, and at times contradictory. On the one hand, it may have protective effects through attenuation of pulmonary inflammation and oxidative stress. On the other hand, it may also have deleterious effects through inhibition of alveolar wound repair, reabsorption of alveolar fluid, and alveolar cell proliferation. Besides, hypercapnia has meaningful effects on lung physiology such as airway resistance, lung oxygenation, diaphragm function, and pulmonary vascular tree.In acute respiratory distress syndrome, lung-protective ventilation strategies using low tidal volume and low airway pressure are strongly advocated as these have strong potential to improve outcome. These strategies may come at a price of hypercapnia and hypercapnic acidosis. One approach is to accept it (permissive hypercapnia); another approach is to treat it through extracorporeal means. At present, it remains uncertain what the best approach is.
PubMed: 31346806
DOI: 10.1186/s40635-019-0239-0 -
Experimental Physiology Apr 2020What is the central question of this study? Are sex difference in the central airways present in healthy paediatric patients? What is the main finding and its...
NEW FINDINGS
What is the central question of this study? Are sex difference in the central airways present in healthy paediatric patients? What is the main finding and its importance? In patients ≤12 years we found no sex differences in central airway luminal area. After 14 years, the males had significantly larger central airway luminal areas than the females. The sex differences were minimized, but preserved when correcting for height. Luminal area is the main determinant of airway resistance and our finding could help explain sex differences in pulmonary system limitations to exercise in paediatric patients.
ABSTRACT
Cross-sectional airway area is the main determinant of resistance to airflow in the respiratory system. In paediatric patients (<18 years), previous evidence for sex differences in cross-sectional airway area was limited to patients with history of pulmonary disease or cadaveric studies with small numbers of subjects. These studies either only report tracheal data and do not include a range of ages or correct for height. Therefore, we sought to assess sex differences in airway luminal area utilizing paediatric patients of varying ages and no history of respiratory disease. Using three-dimensional reconstructions from high-resolution computed tomography scans, we retrospectively assessed the cross-sectional airway area in healthy paediatric females (n = 97) and males (n = 128) over a range of ages (1-17 years). The areas of the trachea, left main bronchus, left upper lobe, left lower lobe, right main bronchus, intermediate bronchus and right upper lobe were measured at three discrete points by a blinded investigator. No differences between the sexes were noted in the cross-sectional areas of the youngest (ages 1-12 years) patients (P > 0.05). However, in patients ≥14 years the cross-sectional areas were larger in the males compared to females in most airway sites. For instance, the cross-sectional size of the trachea was 25% (218 ± 44 vs. 163 ± 24 mm , P < 0.01) larger in males vs. females among ages 13-17 years. When accounting for height, these sex differences in airway areas were attenuated, but persisted. Our results indicate that sex differences in paediatric airway cross-sectional area manifest after age ≥14 years and are independent of height.
Topics: Airway Resistance; Bronchi; Child; Child, Preschool; Female; Humans; Inhalation; Lung; Male; Retrospective Studies; Sex Characteristics; Tomography, X-Ray Computed; Trachea
PubMed: 32003484
DOI: 10.1113/EP088370 -
Intensive Care Medicine Experimental Dec 2022The respiratory system's static compliance (C) and airway resistance (R) are measured during an end-inspiratory hold on volume-controlled ventilation (static method). A...
BACKGROUND
The respiratory system's static compliance (C) and airway resistance (R) are measured during an end-inspiratory hold on volume-controlled ventilation (static method). A numerical algorithm is presented to calculate C and R during volume-controlled ventilation on a breath-by-breath basis not requiring an end-inspiratory hold (dynamic method).
METHODS
The dynamic method combines a numerical solution of the equation of motion of the respiratory system with frequency analysis of airway signals. The method was validated experimentally with a one-liter test lung using 300 mL and 400 mL tidal volumes. It also was validated clinically using airway signals sampled at 32.25 Hz stored in a historical database as 131.1-s-long epochs. There were 15 patients in the database having epochs on volume-controlled ventilation with breaths displaying end-inspiratory holds. This allowed for the reliable calculation of paired C and R values using both static and dynamic methods. Epoch mean values for C and R were assessed by both methods and compared in aggregate form and individually for each patient in the study with Pearson's R and Bland-Altman analysis. Figures are shown as median[IQR].
RESULTS
Experimental method differences in 880 simulated breaths were 0.3[0.2,0.4] mL·cmHO for C and 0[- 0.2,0.2] cmHO·s· L for R. Clinical testing included 78,371 breaths found in 3174 epochs meeting criteria with 24[21,30] breaths per epoch. For the aggregate data, Pearson's R were 0.99 and 0.94 for C and R, respectively. Bias ± 95% limits of agreement (LOA) were 0.2 ± 1.6 mL·cmHO for C and - 0.2 ± 1.5 cmHO·s· L for R. Bias ± LOA median values for individual patients were 0.6[- 0.2, 1.4] ± 0.9[0.8, 1.2] mL·cmHO for C and - 0.1[- 0.3, 0.2] ± 0.8[0.5, 1.2] cmHO·s· L for R.
DISCUSSION
Experimental and clinical testing produced equivalent paired measurements of C and R by the dynamic and static methods under the conditions tested.
CONCLUSIONS
These findings support to the possibility of using the dynamic method in continuously monitoring respiratory system mechanics in patients on ventilatory support with volume-controlled ventilation.
PubMed: 36581716
DOI: 10.1186/s40635-022-00483-2 -
American Journal of Physiology. Lung... Jun 2022Lung resistance () is determined by airway and parenchymal tissue resistance, as well as the degree of heterogeneity in airway constriction. Deep inspirations (DIs) are...
Lung resistance () is determined by airway and parenchymal tissue resistance, as well as the degree of heterogeneity in airway constriction. Deep inspirations (DIs) are known to reverse experimentally induced increase in , but the mechanism is not entirely clear. The first step toward understanding the effect of DI is to determine how each of the resistance components is affected by DI. In the present study, we measured and apparent airway resistance (, which combines the effects of airway resistance and airway heterogeneity) simultaneously before and after a DI in acetylcholine (ACh)-challenged ex vivo sheep lungs. We found that at normal breathing frequency (0.25 Hz) ACh-challenge led to a doubling of , 80.3% of that increase was caused by an increase in ; the increase in apparent tissue resistance () was insignificant. 57.7% of the increase in was abolished by a single DI. After subtracting from , the remaining was mostly independent of ACh-challenge and its reduction after a DI came mostly from the change in the mechanical properties of lung parenchyma. We conclude that at normal breathing frequency, in an unchallenged lung is mostly composed of , and the increase in due to ACh-challenge stems mostly from the increase in and that both and can be greatly reduced by a DI, likely due to a reduction in true airway resistance and heterogeneity, as well as parenchymal tissue hysteresis post DI.
Topics: Airway Resistance; Animals; Inhalation; Lung; Parenchymal Tissue; Respiratory Function Tests; Sheep
PubMed: 35537098
DOI: 10.1152/ajplung.00033.2022 -
The Journal of the Acoustical Society... Jun 2021Steady airflow resistances in semi-occluded airways as well as acoustic impedances in vocalization are quantified from the lungs to the lips. For clinical and voice...
Steady airflow resistances in semi-occluded airways as well as acoustic impedances in vocalization are quantified from the lungs to the lips. For clinical and voice training applications, the primary focus is on two airway conditions, an oral semi-occlusion and a semi-occlusion above the vocal folds. Laryngeal airflow resistance is divided into glottal airflow resistance and epilaryngeal airway resistance. Maximum aerodynamic power is transferred to the vocal tract if the glottal airflow resistance is reduced while the epilaryngeal airway resistance is increased. A semi-occlusion at the lips helps to set up this condition. For the acoustic power transfer, the epilaryngeal airway also serves to match the impedance of the source to the impedance of the vocal tract.
Topics: Humans; Larynx; Phonation; Vocal Cords; Voice; Voice Training
PubMed: 34241487
DOI: 10.1121/10.0005124 -
Respiratory Care Mar 2021A 20% reduction in the FEV is routinely used as an end point for methacholine challenge testing (MCT). Measurement of FEV is effort dependent, and some patients are not...
BACKGROUND
A 20% reduction in the FEV is routinely used as an end point for methacholine challenge testing (MCT). Measurement of FEV is effort dependent, and some patients are not able to perform acceptable and repeatable forced expiration maneuvers. The goal of the present study was to investigate the diagnostic value of airway resistance measurement by forced oscillation technique (FOT), body plethysmography, and interrupter technique compared with the traditionally accepted standard FEV measurement in evaluating the responsiveness to methacholine during MCT.
METHODS
We included in the study adult subjects referred for MCT because of asthma-like symptoms and with normal baseline spirometry. We modified routine MCT protocol by adding the assessment of airway resistance to the measurement of FEV at each step of MCT.
RESULTS
We observed, in the subjects with airway hyper-responsiveness versus those with normal airway responsiveness, a significantly greater percentage change in median (interquartile range) FOT resistance at 10 Hz (25.9% [13.7%-35.4%] vs 16% [15.7%-27.2%]), plethysmographic resistance (70.2% [39.5%-116.3%] vs 37.1% [23.9%-81.9%]), and mean ± SD conductance (-41.3 ± 15.4% vs -29.6 ± 15.9%); and a significantly greater change in mean ± SD FOT reactance at 10 Hz (-0.41 ± 0.48 cm HO/L/s vs -0.09 ± 0.32 cm HO/L/s) and at 15 Hz (-0.29 ± 0.2 cm HO/L/s vs -0.1 ± 0.19 cm HO/L/s). We also recorded significant differences in airway resistance parameters (FOT resistance at 10 Hz, FOT reactance at 15 Hz, plethysmographic airway resistance, and conductance indices as well as interrupter resistance) in FEV non-responders at the onset of respiratory symptoms during MCT compared with baseline.
CONCLUSIONS
Measurements of airway resistance could possibly be used as an alternative method to spirometry in airway challenge. Significant changes in airway mechanics during MCT are detectable by airway resistance measurement in FEV non-responders with methacholine-induced asthma-like symptoms. (ClinicalTrials.gov registration NCT02343419.).
Topics: Adult; Airway Resistance; Bronchial Provocation Tests; Forced Expiratory Volume; Humans; Methacholine Chloride; Spirometry
PubMed: 33203723
DOI: 10.4187/respcare.08331