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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 -
Respiratory Care Dec 2009Spirometry is the most useful and commonly available tests of pulmonary function. It is a physiological test that measures individual inhalation and exhalation volumes... (Review)
Review
Spirometry is the most useful and commonly available tests of pulmonary function. It is a physiological test that measures individual inhalation and exhalation volumes of air as a function of time. Pulmonologists and general-practice physicians commonly use spirometry in their offices in the assessment and management of lung disease. Spirometric indices are well validated and easily interpreted by comparison with established normal values. The remarkable reproducibility of spirometry results from the presence of compliant intrathoracic airways that act as air flow regulators during forced expiration. Because of this anatomic arrangement, expiratory flow becomes dependent solely on the elasticity of the lungs and airway resistance once a certain degree of expiratory force is exerted. Insight into this aspect of respiratory physiology can help in the interpretation of spirometry.
Topics: Airway Obstruction; Airway Resistance; Elasticity; Forced Expiratory Volume; Humans; Lung; Respiratory Mechanics; Spirometry; Vital Capacity
PubMed: 19961639
DOI: No ID Found -
Journal of Clinical Sleep Medicine :... Feb 2011Since on CPAP, the nose is the primary determinant of upper airway resistance, we assess utility of noninvasive measures of nasal resistance during wakefulness as a... (Comparative Study)
Comparative Study
STUDY OBJECTIVES
Since on CPAP, the nose is the primary determinant of upper airway resistance, we assess utility of noninvasive measures of nasal resistance during wakefulness as a predictor of directly assessed upper airway resistance on CPAP during sleep in patients with obstructive sleep apnea/hypopnea syndrome.
METHODS
Patients with complaints of snoring and excessive daytime sleepiness were recruited. 14 subjects underwent daytime evaluations including clinical assessment, subjective questionnaires to assess nasal symptoms and evaluation of nasal resistance with acoustic rhinometry (AR) and active anterior rhinomanometry (RM) in the sitting and supine positions. Patients underwent nocturnal polysomnography on optimal CPAP with measurements of supraglottic pressure to evaluate upper airway resistance. Comparisons were made between nasal resistance using AR and RM during wakefulness, and between AR and RM awake and upper airway resistance during sleep.
RESULTS
Our study shows that measures of awake nasal resistance using AR and RM had little or no correlation to each other in the sitting position, whereas there was significant but weak correlation in the supine position. Upper airway resistance measured while on CPAP during sleep did not show significant relationships to any of the awake measures of nasal resistance (AR or RM).
CONCLUSION
Awake measurements of nasal resistance do not seem to be predictive of upper airway resistance during sleep on CPAP.
Topics: Adult; Airway Resistance; Anthropometry; Circadian Rhythm; Cohort Studies; Continuous Positive Airway Pressure; Female; Humans; Male; Middle Aged; Polysomnography; Rhinomanometry; Rhinometry, Acoustic; Severity of Illness Index; Sleep; Sleep Apnea, Obstructive; Wakefulness
PubMed: 21344056
DOI: No ID Found -
PloS One 2017Surgery patients in Japan undergo routine spirometry testing prior to general anesthesia. The use of a flow sensor during general anesthesia has recently become common.... (Observational Study)
Observational Study
Surgery patients in Japan undergo routine spirometry testing prior to general anesthesia. The use of a flow sensor during general anesthesia has recently become common. However, it is not certain whether the information derived from flow-volume curves is being adequately used for mechanical ventilation management during general anesthesia. So far, there have been no attempts to calculate airway resistance using flow-volume curves. Therefore, we performed a prospective, observational study to investigate the relationship between pre-anesthetic and intra-anesthetic airway resistance in patients scheduled for surgery under general anesthesia. We calculated pre-anesthetic and intra-anesthetic airway resistance in each patient, based on the slopes of flow-volume curves obtained prior to and during general anesthesia. We also calculated endotracheal tube resistance to correct the intra-anesthetic airway resistance values calculated. A total of 526 patients were included in the study, and 98 patients had a forced expiratory volume in the first second/forced vital capacity ratio of < 70%. Pre-anesthetic airway resistance was significantly higher in patients with airflow obstruction than in those without airflow obstruction (p < 0.001), whereas no significant difference in intra-anesthetic airway resistance was found between patients with and without airflow obstruction during mechanical ventilation (p = 0.48). Pre-anesthetic and intra-anesthetic airway resistance values were closer to each other in patients without airflow obstruction, with a mean difference < 1.0 cmH2O L-1s-1, than in those with airflow obstruction, although these respiratory parameters were significantly different (p < 0.001). Intra-anesthetic airway resistance was not related to the FEV1/FVC ratio, regardless of the degree to which the FEV1/FVC ratio reflected pre-anesthetic airway resistance. As compared with patients with airflow obstruction, the mean difference between pre-anesthetic and intra-anesthetic airway resistance was small in patients without airflow obstruction.
Topics: Adolescent; Adult; Airway Resistance; Anesthesia, General; Anesthetics, General; Forced Expiratory Volume; Humans; Prospective Studies; Respiration, Artificial; Spirometry; Tidal Volume; Vital Capacity
PubMed: 28212451
DOI: 10.1371/journal.pone.0172421 -
American Journal of Physiology. Lung... May 2022Lung resistance () and elastance () can be measured during positive or negative pressure ventilation. Whether the different modes of ventilation produce different and...
Lung resistance () and elastance () can be measured during positive or negative pressure ventilation. Whether the different modes of ventilation produce different and is still being debated. Although negative pressure ventilation (NPV) is more physiological, positive pressure ventilation (PPV) is more commonly used for treating respiratory failure. In the present study, we measured lung volume, airway diameter, and airway volume, as well as and with PPV and NPV in explanted sheep lungs. We found that lung volume under a static pressure, either positive or negative, was not different. However, and were significantly higher in NPV at high inflation pressures. Interestingly, diameters of smaller airways (diameters <3.5 mm) and total airway volume were significantly greater at high negative inflation pressures compared with those at high positive inflation pressures. This suggests that NPV is more effective in distending the peripheral airways, likely due to the fact that negative pressure is applied through the pleural membrane and reaches the central airways via the peripheral airways, whereas positive pressure is applied in the opposite direction. More distension of lung periphery could explain why is higher in NPV (vs. PPV), because the peripheral parenchyma is a major source of tissue resistance, which is a part of the that increases with pressure. This explanation is consistent with the finding that during high frequency ventilation (>1 Hz, where reflects airway resistance more than tissue resistance), the difference in between NPV and PPV disappeared.
Topics: Airway Resistance; Animals; Lung; Positive-Pressure Respiration; Respiratory Function Tests; Respiratory Mechanics; Respiratory Physiological Phenomena; Sheep
PubMed: 35272489
DOI: 10.1152/ajplung.00464.2021 -
Journal of Applied Physiology... Jul 2003Airway wall remodeling is well documented for asthmatic airways and is believed to result from chronic and/or short-term exposure to inflammatory stimuli. Airway wall... (Review)
Review
Airway wall remodeling is well documented for asthmatic airways and is believed to result from chronic and/or short-term exposure to inflammatory stimuli. Airway wall remodeling can contribute to airway narrowing as well as to the airway hyperresponsiveness, which is a characteristic abnormality in asthma. However, the potential for airway narrowing could be much worse if it were not for some of the protective effects of remodeling that may help to limit airway narrowing in asthmatic patients. This minireview discusses the evidence for airway wall remodeling and its effects, friend and/or foe, on airway narrowing in asthmatic patients.
Topics: Airway Resistance; Animals; Asthma; Bronchi; Bronchial Hyperreactivity; Elasticity; Epithelium; Humans; Muscle Contraction; Muscle, Smooth
PubMed: 12794101
DOI: 10.1152/japplphysiol.00159.2003 -
The European Respiratory Journal Jan 2006Inhaled corticosteroids suppress airway inflammation and components of airway remodelling in bronchial asthma. In the tracheobronchial (airway) vasculature, these... (Review)
Review
Inhaled corticosteroids suppress airway inflammation and components of airway remodelling in bronchial asthma. In the tracheobronchial (airway) vasculature, these include the inhibition of inflammatory hyperperfusion, microvascular hyperpermeability, mucosal oedema formation, and the formation of new blood vessels (angiogenesis). Corticosteroids are now known to exert their effects on the airway vasculature through genomic and nongenomic mechanisms. Genomic actions involve the regulation of target genes, and suppress most of the vascular elements of inflammation and angiogenesis in the airway. In contrast, nongenomic actions are mediated by rapid cellular mechanisms, and induce transient vasoconstriction in the airway, thereby reversing inflammatory hyperperfusion. The vascular actions of corticosteroids contribute to controlling clinical symptoms of asthma primarily by influencing airway calibre in the lung periphery and airway hyperreactivity. In this review article, recent advances into the understanding of cellular mechanisms and the clinical implications of the interaction of inhaled corticosteroids and the airway vasculature in asthma are reviewed.
Topics: Administration, Inhalation; Adrenal Cortex Hormones; Airway Obstruction; Airway Resistance; Asthma; Blood Flow Velocity; Bronchi; Bronchoconstriction; Genome; Humans; Muscle, Smooth, Vascular; Neovascularization, Physiologic; Vasoconstriction; Vasodilation
PubMed: 16387951
DOI: 10.1183/09031936.06.00048605 -
Journal of Applied Physiology... Nov 2004We have shown that a polynomial equation, FP = AP3 + BP2 + CP + D, where F is flow and P is pressure, can accurately determine the presence of inspiratory flow...
We have shown that a polynomial equation, FP = AP3 + BP2 + CP + D, where F is flow and P is pressure, can accurately determine the presence of inspiratory flow limitation (IFL). This equation requires the invasive measurement of supraglottic pressure. We hypothesized that a modification of the equation that substitutes time for pressure would be accurate for the detection of IFL and allow for the noninvasive measurement of upper airway resistance. The modified equation is Ft = At3 + Bt2 + Ct + D, where F is flow and t is time from the onset of inspiration. To test our hypotheses, data analysis was performed as follows on 440 randomly chosen breaths from 18 subjects. First, we performed linear regression and determined that there is a linear relationship between pressure and time in the upper airway (R2 0.96 +/- 0.05, slope 0.96 +/- 0.06), indicating that time can be a surrogate for pressure. Second, we performed curve fitting and found that polynomial equation accurately predicts the relationship between flow and time in the upper airway (R2 0.93 +/- 0.12, error fit 0.02 +/- 0.08). Third, we performed a sensitivity-specificity analysis comparing the mathematical determination of IFL to manual determination using a pressure-flow loop. Mathematical determination had both high sensitivity (96%) and specificity (99%). Fourth, we calculated the upper airway resistance using the polynomial equation and compared the measurement to the manually determined upper airway resistance (also from a pressure-flow loop) using Bland-Altman analysis. Mean difference between calculated and measured upper airway resistance was 0.0 cmH2O x l(-1) x s(-1) (95% confidence interval -0.2, 0.2) with upper and lower limits of agreement of 2.8 cmH2O x l(-1) x s(-1) and -2.8 cmH2O x l(-1) x s(-1). We conclude that a polynomial equation can be used to model the flow-time relationship, allowing for the objective and accurate determination of upper airway resistance and the presence of IFL.
Topics: Airway Resistance; Feasibility Studies; Humans; Inhalation; Models, Biological; Sleep Apnea Syndromes
PubMed: 15169753
DOI: 10.1152/japplphysiol.01319.2003 -
Chest Aug 2010Airway hyperresponsiveness (AHR) is a clinical feature of asthma and is often in proportion to the underlying severity of the disease. To understand AHR and the... (Review)
Review
Airway hyperresponsiveness (AHR) is a clinical feature of asthma and is often in proportion to the underlying severity of the disease. To understand AHR and the mechanisms that contribute to these processes, it is helpful to divide the airway components that affect this feature of asthma into "persistent" and "variable" categories. The persistent component of AHR represents structural changes in the airway, whereas the variable feature relates to inflammatory events. Insight into how these interrelated components of AHR can contribute to asthma is gained by studying treatment effects and models of asthma provocation.
Topics: Airway Resistance; Animals; Asthma; Breath Tests; Bronchial Hyperreactivity; Bronchoconstriction; Humans
PubMed: 20668012
DOI: 10.1378/chest.10-0100 -
The European Respiratory Journal Feb 1997Pulmonary surfactant research has an increasing impact on treatment considerations in adult respiratory disorders, above all acute respiratory distress syndrome (ARDS).... (Review)
Review
Pulmonary surfactant research has an increasing impact on treatment considerations in adult respiratory disorders, above all acute respiratory distress syndrome (ARDS). Obstructive airways diseases have only been sporadically addressed in this respect. In the last decade, direct and circumstantial evidence for surfactant as a contributing factor in the regulation of airway calibre has emerged. Morphologically, a bronchiolar surfactant layer has been demonstrated, whereby the airways are mostly supplied by alveolar surfactant components via the mucociliary escalator. Functionally, prevention of airway film collapse and collapse of the airway walls are important surfactant properties in maintaining airway stability. In addition to its surface activity, airway surfactant improves bronchial clearance and regulates airway liquid balance, thus indirectly modulating airway wall thickness and airway diameter. Surfactant has furthermore been shown to modulate the function of respiratory inflammatory cells. Its immunomodulatory activity includes suppression of cytokine secretion and transcription factor activation. This may be of importance in the inflammatory network of asthma. Thus, dysfunction of surfactant in obstructive lung disease might be one of the mechanisms leading to increased airway resistance, which is commonly thought to be due to narrowing of airways under humoral and nervous control. In animal models of asthma, surfactant dysfunction was demonstrated, which was possibly due to protein inhibition. Furthermore, surfactant therapy seems to be capable of preventing allergen-induced bronchoconstriction. Human studies on surfactant impairment in obstructive airways diseases are still scarce but the data available are consistent with animal studies. Antiobstructive pharmacotherapy, mainly with corticosteroids, might influence and improve airway surfactant balance, but the exact mechanisms and the overall effect of pharmacotherapy on surfactant function in obstructive airways disease has to be further elucidated. Our knowledge about the role of pulmonary surfactant in obstructive airways disease is still limited, but there is convincing evidence that pulmonary surfactant plays a role in keeping the airways open.
Topics: Airway Resistance; Bronchoconstriction; Humans; Inflammation; Lung Diseases, Obstructive; Pulmonary Surfactants; Smoking
PubMed: 9042653
DOI: 10.1183/09031936.97.10020482