Airway Resistance Research Articles

Comparison of airway resistance and wall shear stress between non- and bronchial pattern images in cats by computational simulation

Comparison of airway resistance and wall shear stress between non- and bronchial pattern images in cats by computational simulation

Kiss1 receptor knockout exacerbates airway hyperresponsiveness and remodeling in a mouse model of allergic asthma

BackgroundIn asthma, sex-steroids signaling is recognized as a critical regulator of disease pathophysiology. However, the paradoxical role of sex-steroids, especially estrogen, suggests that an upstream mechanism or even independent of estrogen plays an important role in regulating asthma pathophysiology. In this context, in our previous studies, we explored kisspeptin (Kp) and its receptor Kiss1R’s signaling in regulating human airway smooth muscle cell remodeling in vitro and airway hyperresponsiveness (AHR) in vivo in a mouse (wild-type, WT) model of asthma. In this study, we evaluated the effect of endogenous Kp in regulating AHR and remodeling using Kiss1R knockout (Kiss1R−/−) mice.MethodsC57BL/6J WT (Kiss1R+/+) and Kiss1R−/− mice, both male and female, were intranasally challenged with mixed-allergen (MA) and/or phosphate-buffered saline (PBS). We used flexiVent analysis to assess airway resistance (Rrs), elastance (Ers), and compliance (Crs). Following this, broncho-alveolar lavage (BAL) was performed for differential leukocyte count (DLC) and cytokine analysis. Histology staining was performed using hematoxylin and eosin (H&E) for morphological analysis and Masson’s Trichrome (MT) for collagen deposition. Additionally, lung sections were processed for immunofluorescence (IF) of Ki-67, α-smooth muscle actin (α-SMA), and tenascin-c.ResultsInterestingly, the loss of Kiss1R exacerbated lung function and airway contractility in mice challenged with MA, with more profound effects in Kiss1R−/− female mice. MA-challenged Kiss1R−/− mice showed a significant increase in immune cell infiltration and proinflammatory cytokine levels. Importantly, the loss of Kiss1R aggravated Th2/Th17 biased cytokines in MA-challenged mice. Furthermore, histology of lung sections from Kiss1R−/− mice showed increased collagen deposition on airway walls and mucin production in airway cells compared to Kiss1R+/+ mice. In addition, immunofluorescence analysis showed loss of Kiss1R significantly aggravated airway remodeling and subsequently AHR.ConclusionsThese findings demonstrate the importance of inherent Kiss1R signaling in regulating airway inflammation, AHR, and remodeling in the pathophysiology of asthma.

The Impact of Pneumoperitoneum on Mean Expiratory Flow Rate: Observational Insights from Patients with Healthy Lungs

Background/Objectives: Surgical pneumoperitoneum (PP) significantly impacts volume-controlled ventilation, characterized by reduced respiratory compliance, elevated peak inspiratory pressure, and an accelerated expiratory phase due to an earlier onset of the airway pressure gradient. We hypothesized that this would shorten expiratory time, potentially increasing expiratory flow rate compared to pneumoperitoneum conditions. Calculations were performed to establish correlations between respiratory parameters and the mean increase in expiratory flow rate relative to baseline. Methods: Mechanical ventilation parameters were recorded for 67 patients both pre- and post-PP. Ventilator settings were standardized with a tidal volume of 6 mL/kg, a respiratory rate of 12 breaths per minute, a PEEP of 3 cmH2O, an inspiratory time of 2 s, and an inspiratory-to-expiratory ratio of 1:1.5 (I:E). Results: The application of PP increased both peak inspiratory pressure and mean expiratory flow rate by 28% compared to baseline levels. The elevated intra-abdominal pressure of 20 cmH2O resulted in a 34% reduction in dynamic chest compliance, a 50% increase in elastance, and a 20% increase in airway resistance. The mean expiratory flow rate increments relative to baseline showed a significant negative correlation with elastance (p = 0.0119) and a positive correlation with dynamic compliance (p = 0.0028) and resistance (p = 0.0240). Conclusions: A PP of 20 cmH2O resulted in an increase in the mean expiratory flow rate in the conventional I:E ratio in the volume-ventilated mode. PP reduces lung and chest wall compliance by elevating the diaphragm, compressing the thoracic cavity, and increasing airway pressures. Consequently, the lungs and chest wall stiffen, requiring greater ventilatory effort and accelerating expiratory flow due to increased airway resistance and altered pulmonary mechanics. Prolonging the inspiratory phase through I:E ratio adjustment helps maintain peak inspiratory pressures closer to baseline levels, and this method enhances the safety and efficacy of mechanical ventilation in maintaining optimal respiratory function during laparoscopic surgery.

Aging, brain-derived neurotrophic factor, and allergen-induced pulmonary responses in mice.

Asthma in the elderly is being recognized as more severe, resistant to standard therapies, and having greater morbidity. Therefore, it comes important to understand the impact of aging-associated airway structure and function changes towards pathogenesis of asthma in the elderly. Here, airway smooth muscle plays important roles in airway hyperreactivity and structural remodeling. The role of smooth muscle in asthma can be modulated by growth factors (including neurotrophins such as brain-derived neurotrophic factor (BDNF)) and pro-inflammatory senescence factors. In this study, we investigated aging effects on airway hyperreactivity, structural remodeling, inflammation, and senescence in a mouse model of allergic asthma. C57BL/6J wildtype mice or smooth muscle-specific BDNF knockout mice at 4, 18 and 24 months of age were intranasally exposed to mixed allergens (ovalbumin, aspergillus, Alternaria, and house dust mite) over 4 weeks. Assessing lung function by FlexiVent, we found that compared with 4 month old mice, 18 and 24 month old C57BL/6J mice showed decreased airway resistance and increased airway compliance after PBS or MA treatment. Deletion of smooth muscle BDNF blunted airway hyperreactivity in aged mice. Lung histology analysis revealed that aging increased bronchial airway thickness and decreased lung inflammation. Multiplex assays showed that aging largely reduced allergen-induced lung expression of proinflammatory chemokines and cytokines. By immunohistochemistry staining, we found that aging increased bronchial airway expression of senescence markers, including p21, phospho-p53 and phospho-gH2A.X. Our data suggest that aging associated increase of airway senescence in the context of allergen exposure may contribute to asthma pathology in the elderly.

Pulmonary function using impulse oscillometry system and clinical outcomes at age 4 years in children born extremely preterm with or without bronchopulmonary dysplasia

This study aimed to describe the early assessment of lung function and respiratory morbidity in children born extremely preterm with or without bronchopulmonary dysplasia (BPD). MethodsThis was a prospective study including all the children born at gestational age ≤28 weeks who received treatment in the NICU of the Centre Intercommunal de Créteil in France, from January 2006 to March 2012. Lung function, using the impulse oscillometry system, respiratory morbidity and growth were assessed at age 4 years. Lung function and clinical course of children were compared in children with and without BPD. ResultsWe included 136 extremely premature children; 26 (19 %) had BPD. Children with and without BPD did not significantly differ in resistance measurements at 5 Hz (R5) and 20 Hz (R20) and reactance (X5) measurements at age 4 years. A total of 104 (76 %) pre-term children had respiratory resistance R5 above the 95th percentile for the reference population (z-score >1.64), regardless of BPD status. The mean (SD) R5 z-score for all children was 2.1 (±0.7), whereas the mean (SD) R20 was in the normal range (z-score = 1.1 [±0.3]). After treatment with bronchodilators, all children showed no significant change in resistance. The prevalence of asthma symptoms at age 4 years was common and estimated at 30 % regardless of BPD status. ConclusionEarly assessment of lung function by the impulse oscillometry system revealed that most preschool children who were born extremely preterm had abnormal total airway resistance regardless of BPD status. The system is an essential tool for the early assessment of children born prematurely.

Progress in impulse oscillometry on chronic obstructive pulmonary disease

Impulse oscillometry (IOS) is a force-free, easy-to-use tool for the detection of airway resistance. Compared with spirometry, IOS is more sensitive in detecting early abnormalities in chronic obstructive pulmonary disease (COPD), and IOS parameters have potential research value in identifying the progression of COPD and monitoring the effect of treatment. This review aimed to highlight the significant research findings of IOS in chronic obstructive pulmonary disease and to address the urgent issue that need to be resolved.

Upper airway resistance during use of a laryngeal mask airway is flow-dependent and dominated by the laryngeal resistance

During use of a laryngeal mask airway, resistance of the device and larynx contribute to the upper airway resistance. Detailed understanding of this combined resistance is crucial to support spontaneously breathing patients appropriately or to take the right measures during respiratory problems. However, their resistive behavior and which of these components determine the upper airway resistance predominantly, has not been characterized systematically. Pressure-flow-relationships of different sizes of a laryngeal mask airway, of a laryngeal model with vocal cord angles between 10° and 60° and of the combination of a laryngeal mask airway size 4 and the laryngeal model were measured. Results were fitted to the expanded Rohrer’s equation and resistances were calculated. The laryngeal mask airway and the laryngeal model showed a nonlinear flow-dependent resistive behavior. Decreasing size of the laryngeal mask airway, decreasing vocal cord angles, and increasing flow rates resulted in increased resistances (all p < 0.001). Resistance of the laryngeal mask and the laryngeal model added up to the combined resistance in a summative way, where the vocal cord angle determines 59–98% of the combined resistance in adults. The upper airway resistance during the use of a laryngeal mask airway is a summative resistance with a flow-dependent, nonlinear behavior. Upper airway resistance in adults is primarily determined by the vocal cord angle during use of a laryngeal mask.

Phenotypes based on respiratory drive and effort to identify the risk factors when P0.1 fails to estimate ∆PES in ventilated children.

Monitoring respiratory effort and drive during mechanical ventilation is needed to deliver lung and diaphragm protection. Esophageal pressure (∆PES) is the gold standard measure of respiratory effort but is not routinely available. Airway occlusion pressure in the first 100ms of the breath (P0.1) is a readily available surrogate for both respiratory effort and drive but is only modestly correlated with ∆PES in children. We sought to identify risk factors for P0.1 over or underestimating ∆PES in ventilated children. Secondary analysis of physiological data from children and young adults enrolled in a randomized controlled trial testing lung and diaphragm protective ventilation in pediatric acute respiratory distress syndrome (PARDS) (NCT03266016). ∆PES (∆PES-REAL), P0.1 and predicted ∆PES (∆PES-PRED = 5.91*P0.1) were measured daily to identify phenotypes based upon the level of respiratory effort and drive: one passive (no spontaneous breathing), three where ∆PES-REAL and ∆PES-PRED were aligned (low, normal, and high effort and drive), two where ∆PES-REAL and ∆PES-PRED were mismatched (high underestimated effort, and overestimated effort). Logistic regression models were used to identify factors associated with each mismatch phenotype (High underestimated effort, or overestimated effort) as compared to all other spontaneous breathing phenotypes. We analyzed 953 patient days (222 patients). ∆PES-REAL and ∆PES-PRED were aligned in 536 (77%) of the active patient days. High underestimated effort (n = 119 (12%)) was associated with higher airway resistance (adjusted OR 5.62 (95%CI 2.58, 12.26) per log unit increase, p < 0.001), higher tidal volume (adjusted OR 1.53 (95%CI 1.04, 2.24) per cubic unit increase, p = 0.03), higher opioid use (adjusted OR 2.4 (95%CI 1.12, 5.13, p = 0.024), and lower set ventilator rate (adjusted OR 0.96 (95%CI 0.93, 0.99), p = 0.005). Overestimated effort was rare (n = 37 (4%)) and associated with higher alveolar dead space (adjusted OR 1.05 (95%CI 1.01, 1.09), p = 0.007) and lower respiratory resistance (adjusted OR 0.32 (95%CI 0.13, 0.81), p = 0.017). In patients with PARDS, P0.1 commonly underestimated high respiratory effort particularly with high airway resistance, high tidal volume, and high doses of opioids. Future studies are needed to investigate the impact of measures of respiratory effort, drive, and the presence of a mismatch phenotype on clinical outcome. NCT03266016; August 23, 2017.

Real-World Efficacy of Biological Therapies in Severe Asthma: A Focus on Small Airways.

Background: Severe asthma is a challenging condition that often resists traditional treatments and requires high-dose inhaled corticosteroids and other controllers to manage uncontrolled symptoms. Recent advances include the use of biologic agents targeting specific inflammation pathways, which have improved symptom control and quality of life, although their effects on small airways remain less understood. Methods: This prospective observational study, conducted at Tor Vergata University Hospital in Rome from July 2021 to March 2024, aims to evaluate the efficacy of treatments in patients with uncontrolled severe asthma. It involves baseline assessments and follow-ups at 1 and 3 months post-biological therapy initiation, focusing on both spirometric and non-spirometric (oscillometry) measurements of the small airways to provide a comprehensive evaluation of respiratory function. Results: This study, conducted from July 2021 to March 2024, enrolled 40 patients with severe asthma, ultimately analyzing data from 31 participants who underwent biological therapy. The results showed significant improvements in asthma symptoms, the ACT scores increased significantly from visit 1 to visit 2 (p = 0.00008) and from visit 1 to visit 3 (p = 0.00047), and pulmonary function tests, with notable increases in FEV1 (from visit 1 (74.97 ± 23.43%) to visit 2 (82.96 ± 26.57%, p = 0.041) and to visit 3 (88.89 ± 31.41%, p = 0.003)) and quality of life scores, and substantial reductions in specific airway resistance and small airway dysfunction markers (the PEF, %pr post-BD showed significant improvement from visit 1 to visit 3 (p = 0.012)). However, oscillometric measurements showed no significant changes post-therapy. Conclusions: The study concluded that there was an improvement in the small airways measured by non-oscillometric values, without significant improvements in oscillometric parameters. Additionally, a significant improvement in symptoms was observed after the first month of therapy. There was also a significant increase in respiratory function after one to three months of therapy.

Endonasal Thermal Imaging Before and After Nasal Airway Surgery.

Nasal airway surgery is often applied when treatment fails to relieve nasal obstruction. However, surgery that improves airflow does not always alleviate the symptoms of nasal obstruction. The perception of nasal breathing is likely more related to changes in mucosal temperature than the mechanical sensation of flow or pressure. This study aims to measure intranasal mucosal temperature pre-and post-surgery using endonasal thermal imaging, exploring its correlation with subjective nasal breathing and objective airflow measurements. A prospective study of adult patients with nasal obstruction managed with nasal airway surgery was performed. Intranasal mucosal temperatures were determined using the thermal endonasal image of the nasal passage produced by the infrared radiometric thermal camera (FILR VS290). A comparison was made between the mean values of mid-expiration (ExT) and mid-inspiration (InT) temperature data (internal nasal valve, nasal cavity, inferior turbinate, and overall airway [mean value]) and visual analog scale (VAS), Nasal Obstruction Symptom Evaluation (NOSE) scale and nasal airway resistance (NAR) before and after surgery. Seven patients (35.14 ± 16.45 years, 57.14% female) were included. All NOSE, VAS, and NAR improved after surgery (59.29 ± 10.89 vs 17.14 ± 14.64; P < .001, 64.50 ± 26.79 vs 18.57 ± 19.99; P < .001, 0.82 ± 0.48 vs 0.34 ± 0.11 Pa/cm3/s; P = .002, respectively). ExT, InT, and the difference between ExT and InT of three areas and overall airway were similar between pre-and post-surgery. No statistically significant correlations were found between intranasal mucosal temperature, VAS, NOSE, and NAR at pre-and post-surgery except for the difference between ExT and InT of overall airway and NOSE pre-operative (Pearson r = 0.57; 95% CI 0.06-1.09; P = .03). Endonasal thermal imaging can assess the intranasal mucosal temperature of a patient. However, more precise imaging of the nasal passages and data acquisition are required to establish mucosal temperature as an objective measure of nasal obstruction before and after nasal airway surgery in a clinical setting.

Curcumin Alleviates Airway Inflammation in Cough-Variant Asthmatic Rats by Modulating M1/M2 Macrophage Polarization.

With the increase of environmental pollution and atypical pathogen infections, the incidence of cough variant asthma (CVA) has been increasing annually, making it a pressing issue of the medical community. This study aims to observe the ameliorative effect of curcumin on a rat model of cough variant asthma. A rat model of cough variant asthma was induced by sensitization with ovalbumin combined with aluminum hydroxide (Al(OH)3), followed by repeated excitations. The drug was administered on the day of the initial nebulized attack, and gavage was administered for 14 d. Pathological changes in the lung tissues were observed, along with the assessment of cough susceptibility and airway resistance. The number of inflammatory cell eosinophils and leukocytes were determined in alveolar lavage fluid. Additionally, serum inflammatory factors and lung tissues Matrix Metalloproteinase-9 (MMP-9) protein were assessed. The level of M1/M2 macrophages was also detected. Following the administration of curcumin, there was reduced inflammatory infiltration, less disordered arrangement of the lung tissue, and decreased abnormal proliferation of lung tissues in cough variant asthma rats compared to the model group. Curcumin treatment led toa notable reduction in cough frequency, a significant decrease in pro-inflammatory factor concentration levels in serum and inflammatory cell counts in the alveolar lavage fluid, and a marked increase in anti-inflammatory factor levels (p < 0.05). Additionally, curcumin administration led to a significant increase in M2-type macrophage levels, while simultaneously decreasing the levels of M1-type macrophages (p < 0.05). The administration of curcumin effectively ameliorates ovalbumin-induced airway inflammation in cough-variant asthma rats. This effect is attributed to modulating macrophage polarization towards the anti-inflammatory M2 phenotype, thereby reducing airway inflammation, airway hyperresponsiveness, and lung tissue injury.

Vaping causes an acute BMI-dependent change in pulmonary blood flow.

Vaping use has skyrocketed especially among young adults, however there is no consensus on how vaping impacts the lungs. We aimed to determine whether there were changes in lung function acutely after a standard vaping session or if there were differences in lung function metrics between a healthy never-vaping cohort (N = 6; 27.3 ± 3.0 years) and a young asymptomatic vaping cohort (N = 14; 26.4 ± 8.0 years) indicating chronic changes. Pulmonary function measurements and impulse oscillometry were obtained on all participants. Oxygen-enhanced and Arterial Spin Labelling MRI were used to measure specific ventilation and perfusion, respectively, before and after vaping, and in the control cohort at baseline. MRI metrics did not show any significant differences in specific ventilation or perfusion after vaping. Heart rate increased post-vaping (68.1 ± 10.5 to 71.3 ± 8.7, p = 0.020); however, this and other metrics did not show a nicotine dose-dependent effect. There was a significant negative correlation between BMI and change in mean perfusion post-vaping (p = 0.003); those with normal/low BMI showing an increase in perfusion and vice versa for high BMI. This may be due to subjects lying supine during vaping inhalation. Pulmonary function metrics indicative of airways resistance showed significant differences between the vaping and control cohorts indicating early airway changes.

Outcomes of heliox use in children with respiratory compromise: A 10-year single institution experience.

Heliox, a mixture of helium and oxygen, has been shown to improve laminar airflow and decrease airway resistance in children. This study aims to describe the outcomes of heliox use in children with respiratory compromise and to identify variables associated with a need for airway surgical intervention. A retrospective cohort study of patients who received heliox between 2012 and 2022 at a tertiary care children's hospital. A hundred and thirty-eight heliox treatments were recorded in 119 children. Twelve patients were excluded. Most (n = 100, 84%) patients had significant comorbidities. On average, patients spent a cumulative mean of 94 ± 187 h on heliox therapy per hospital admission. Patients with croup or asthma without known airway pathology presented at an older age than patients with other indications for heliox therapy (4.0 ± 4.7 vs. 2.2 ± 3.6 years, p = 0.04) and were significantly less likely to have background diseases (n = 14, 52% vs. n = 74, 93%, p < 0.0001). Overall, 51 (47.7%) patients were recommended tracheostomy placement, airway reconstruction, or palliative care. Cumulative use of heliox for more than 47 h was associated with an increased risk of needing tracheostomy or airway reconstruction (odds ratio 6.2, 95% confidence intervals 2.56-14.13, p < 0.0001). In multivariable regression analysis, neuromuscular disease, intracranial neuropathology, and cumulative time of heliox were associated with a need for definitive airway intervention. Heliox may be used as a temporizing agent in children with upper airway obstruction. The effectiveness of heliox use for more than 47 h in children, especially in the presence of neuromuscular disease and intracranial neuropathology should be reconsidered.Level of evidence: 4.

Comparison of Nebulized Glycopyrronium with a Combination of Salbutamol and Ipratropium on Ventilatory Parameters in Critically Ill Mechanically Ventilated Patients of Chronic Obstructive Pulmonary Disease: An Observational Study.

The present study examined the duration of bronchodilation induced by nebulized glycopyrronium bromide (GB) and compared its effectiveness and incidence of any side effects with the combination of salbutamol and ipratropium bromide (SI) in critically ill mechanically ventilated chronic obstructive pulmonary disease (COPD) patients. This prospective, observational study was conducted in mechanically ventilated adult patients of COPD (18-75 years). Data of two groups of patients were collected for 12 hours each for three consecutive days after the nebulization - Group I: those who received 25 µg of GB, and Group II: those who received 1.25 mg of levo-salbutamol and 500 µg of ipratropium by nebulization. A significantly higher number of patients in group II had copious secretions. The mean static compliance was comparable at all time intervals, whereas the mean airway pressure was significantly lower in group II from 15 minutes to 4 hours post-nebulization. In group I, the onset of bronchodilation was 30 minutes on days 1 and 3, and 60 minutes on day 2, whereas, in group II, it was 60 minutes on days 1 and 2 and 30 minutes on day 3. In group I, bronchodilation was 10 hours on day 1 and 12 hours each on days 2 and 3, whereas in group II, bronchodilation was 4 hours on day 1 and 6 hours each on day 2 and 3. Compared with SI, GB nebulization resulted in lesser respiratory secretions, a longer duration of action in terms of lowered airway resistance, and no adverse effects like hypertension, tachycardia, or desiccation of respiratory secretions. Priya P, Nath SS, Kumar V, Kumar S. Comparison of Nebulized Glycopyrronium with a Combination of Salbutamol and Ipratropium on Ventilatory Parameters in Critically Ill Mechanically Ventilated Patients of Chronic Obstructive Pulmonary Disease: An Observational Study. Indian J Crit Care Med 2024;28(10):963-969.

Impact of dexmedetomidine-assisted anesthesia in elderly patients undergoing radical resection of colon cancer.

Radical resection of colon cancer under general anesthesia is one of the main treatment methods for this malignancy. However, due to the physiological characteristics of elderly patients, the safety of perioperative anesthesia needs special attention. As an α2-adrenergic receptor agonist, dexmedetomidine (Dex) has attracted much attention from anesthesiologists due to its stabilizing effect on heart rate and blood pressure, inhibitory effect on inflammation, and sedative and analgesic effects. Its application in general anesthesia may have a positive impact on the quality of anesthesia and postoperative recovery in elderly patients undergoing radical resection of colon cancer. To investigate the anesthetic effects of Dex during radical surgery for colon cancer under general anesthesia in elderly patients. A total of 165 colon cancer patients who underwent radical surgery for colon cancer under general anesthesia at Qingdao University Affiliated Haici Hospital, Qingdao, China were recruited and divided into two groups: A and B. In group A, Dex was administered 30 min before surgery, while group B received an equivalent amount of normal saline. The hemodynamic changes, pulmonary compliance, airway pressure, inflammatory factors, confusion assessment method scores, Ramsay Sedation-Agitation Scale scores, and cellular immune function indicators were compared between the two groups. Group A showed less intraoperative hemodynamic fluctuations, better pulmonary compliance, and lower airway resistance compared with group B. Twelve hours after the surgery, the serum levels of TLR-2, TLR-4, IL-6, and TNF-α in group A were significantly lower than those of group B (P < 0.05). After extubation, the Ramsay Sedation-Agitation Scale score of group A patients was significantly higher than that of group B patients, indicating a higher level of sedation. The incidence of delirium was significantly lower in group A than in group B (P < 0.05). The use of Dex as an adjunct to general anesthesia for radical surgery in elderly patients with colon cancer results in better effectiveness of anesthesia.

Influence of catheter thickness on respiratory physiology during less invasive surfactant administration in extremely preterm infants.

Delivering surfactant via thin catheters (minimal-invasive surfactant therapy (MIST); less invasive surfactant administration (LISA)) has become a common procedure. However, the effect of tracheal obstruction caused by catheters of different sizes on tracheal resistance in extremely low gestational age newborns (ELGANs) is unknown. To investigate the effect of catheters size 3.5, 5 and 6 French on airway resistance in ELGANs of 23-28 weeks gestational age during LISA, we performed calculations based on Hagen-Poiseuille's law and compared these with a clinically and physically more accurate method: computational fluid dynamics (CFD) simulations of respiratory airflow, performed in 3D virtual airway models derived from MRI. The presence of the above catheters decreased the cross-sectional area of the infants' tracheal entrance (the cricoid ring) by 13-53%. Hagen-Poiseuille's law predicted an increase in resistance by 1.5-4.5 times and 1.3-2.6 times in ELGANs born at 23 and 28 weeks, respectively. However, CFD simulations demonstrated an even higher increase in resistance of 3.4-85.1 and 1.1-3.5 times, respectively. The higher calculated resistances were due to the extremely narrow remaining lumen at the glottis and cricoid with the catheter inserted, resulting in a stronger glottal jet and turbulent airflow, which was not predicted by Hagen-Poiseuille. Catheter thickness can greatly increase tracheal resistance during LISA-procedures in ELGANs. Based on these models, it is recommended to use the thinnest catheter possible during LISA in ELGANs to avoid unnecessary increases in airway resistance in infants already experiencing dyspnea due to respiratory distress syndrome.

The Effect of Green Tea Extract on Pulmonary Inflammation in Nanoparticles-Exposed Mice.

Titanium dioxide nanoparticles (TiO2 NPs) are air pollutants that exacerbate chronic respiratory diseases such as asthma and Chronic Obstructive Pulmonary Disease (COPD) However, little is known about the mechanism underlying the antipollutant effects of green tea extract (GTE). This study evaluates the efficacy and mechanism of GTE on lung inflammation and fibrosis in mice exposed to TiO2 NPs. The TiO2 NPs model is induced by having mice inhale TiO2 NPs, while controls receive an equivalent volume of saline. Treatment with oral GTE is initiated after TiO2 NPs inhalation and is given once daily for 4 weeks. Airway resistance and pulmonary inflammation are increased in mice exposed to TiO2 NPs. GTE treatment reduces the airway inflammation and airway resistance, and attenuates the pathological changes including lung fibrosis compared to the mice exposed to TiO2 NPs. With GTE, there are no significant increases in cytokines and immunoglobulin E (IgE) in mice exposed to TiO2 NPs. GTE inhibits matrix metalloproteinases (MMPs) and apoptotic factors induced by TiO2 NPs exposure, and these protective effects of GTE are closely related to the mitogen-activated protein kinase (MAPK) signaling pathway. GTE modulates pulmonary inflammation in mice exposed to air pollutants, suggesting that GTE may be beneficial in respiratory diseases exacerbated by such pollutants.

Do not ignore mouth breathing syndrome: respiratory functions are affected in early childhood.

Impulse oscillometry (IOS) is a useful test for measuring pulmonary resistance and reactance from the early ages. We aimed to investigate the etiological factors of mouth breathing syndrome (MB), its effects on respiratory functions, and to compare the results with those of children with nasal breathing (NB). This prospective cross-sectional study investigated children aged 3-7 years with MB (n=202) and NB (n=127) admitted to the pediatric allergy clinic between January 2023-2024. The MB group was evaluated for etiological factors by means of otorhinolaryngological examination. Respiratory function tests were evaluated using IOS and were repeated two months after appropriate treatment. Adenoid hypertrophy (AH-44.0%), allergic rhinitis (AR-11.3%) and AH co-existent with AR (34.6%) were the principal causes of MB. Entire airway resistance was higher, upper and lower airway reactance were lower in the MB group compared to the NB group. No difference was detected in terms of IOS parameters between the first and second visits of MB group. Upper and entire airway resistance parameters were higher in children with AH and AH co-existent with AR groups compared to the non-obstructive group. Entire airway resistance was higher, upper and lower airway reactance were lower, in children with adenoid size&gt;50% compared to those with adenoid size mouth breathing, allergic rhinitis, adenoids, respiratory function test, pediatrics.

Protective effects of Parkin knockout on asthma-induced changes in juvenile mice: inflammation, airway resistance, and oxidative stress

Objective This study aimed to explore the effects of Parkin (Prkn) knockout in a juvenile mouse model of asthma. Methods Prkn knockout (KO) and wild type (WT) mice were utilized to establish a juvenile mouse asthma model. The asthma model involved exposure to hyperoxia/ovalbumin (OVA), encompassing hyperoxia from postnatal day 1 (P1) to P7, sensitization on P21 and P28, and challenge from P36 to P42. Room air/phosphate-buffered saline (PBS) served as the control condition. Following airway resistance measurement, bronchoalveolar lavage fluid (BALF) was collected for cellular analysis, and lung tissues were subjected to histological examination and oxidative stress assessment. Serum levels of ovalbumin-specific immunoglobulin E (IgE), total IgE, interleukin-4 (IL-4), IL-5, and IL-13 were quantified using enzyme-linked immunosorbent assay (ELISA). Results WT mice exposed to hyperoxia/OVA showed decreased body weight and increased airway resistance compared to those exposed to control condition. Conversely, KO mice exhibited increased body weight under asthma conditions. KO mice with asthma had reduced total cell counts, along with lower levels of lymphocytes, eosinophils, and neutrophils, compared to WT asthma mice. Histological assessment showed attenuated inflammation and reduced collagen deposition in KO mice relative to WT mice, with lower serum levels of inflammatory markers and improved lung oxidative stress profiles. No significant differences were observed between KO and WT mice under room air/PBS conditions. Conclusions Parkin knockout in juvenile mice mitigates asthma-related alterations in airway resistance, histopathological changes, inflammation status, and oxidative stress. These findings highlight a protective role of Parkin deficiency against asthma-associated pathologies.

Impact of Nebulized BromAc® on Mucus Plug Clearance in a Mechanically Ventilated Ex Vivo Ovine Lung Model of Obstructive Respiratory Conditions.

Mucus plugging of the respiratory tract occurs in airway diseases, including asthma, chronic obstructive pulmonary disease, and cystic fibrosis. It can cause blockage of the airways, leading to breathlessness and lung failure. Here, we used a ventilatory setup to demonstrate the effect of BromAc® in dissolving mucus plugs in a novel ex vivo ovine obstructive lung model. Mucus simulant was filled into the trachea of freshly slaughtered ovine lungs and ventilated via an endotracheal tube (ETT) using Continuous Mandatory Ventilation. Predetermined single or repeated doses of Bromelain, Acetylcysteine (Ac), BromAc®, and saline control were administered via an Aerogen® vibrating nebulizer and ventilated for 30 or 60 min. Ventilatory recording of resistance, compliance, and tidal volume was conducted, and rheology pre- and post-treatment were measured. A significant decline in airway resistance (p < 0.0001) compared to the saline control was observed when treated with Bromelain, Ac, and BromAc®, with the latter showing a stronger mucolytic effect than single agents. The decline in resistance was also effective in shorter time points (p < 0.05) at lower doses of the drugs. Changes in compliance, peak pressure, and tidal volume were not observed after administration of the drugs. Rheology measurements revealed that BromAc®TM significantly reduced the viscosity of the mucin at the end of 30 min and 60 min time points (p < 0.001) compared to the saline control. BromAc® showed complete dissolution of the respiratory mucus simulant and improved ventilatory airflow parameters in the ex vivo ovine model.