Initiatives to improve lung and sleep health in children: Delphi consensus from the pediatrics, pulmonary, and sleep conference.

BACKGROUND AND OBJECTIVES: The lung and sleep health of adults is heavily influenced by early factors, both genetic and environmental; therefore, optimizing respiratory health begins in childhood. Multiple barriers impede improvements in lung and sleep health for children. First, the traditional siloing between general pediatric care in the community, pediatric pulmonary and sleep subspecialty care, and the research community limits the translation of knowledge into practice. Additionally, identifying and addressing health disparities remains a challenge. The 2021 NHLBI-sponsored workshop "Defining and Promoting Pediatric Pulmonary Health (DAP3H)" was a first step in defining critical gaps in our current healthcare system in identifying and optimizing lung and sleep health in children. The workshop identified key opportunities including measuring pulmonary function in young children, sleep-focused outcomes, developing biomarkers, and longitudinal research cohorts. To expand on the work of DAP3H and continue initiatives to improve childhood lung and sleep health, the Pediatrics & Pulmonary Network: Improving Health Together conference was held in 2023. STUDY DESIGN: A modified Delphi process was applied to form consensus surrounding gaps, barriers, and action items, with the goal of identifying the most urgent opportnities for improving childhood lung and sleep health. RESULTS: Cross-cutting foundational principles were identified as: (1) Authentic Stakeholder Collaboration & Engagement, (2) Reach & Implementation in Real World Settings, (3) Understanding Current Landscape & Resources and (4) Purposeful Diversity, Equity, & Inclusion Initiatives. CONCLUSIONS: To improve lung and sleep health in children, these principles should be the foundation for research design, development, and implementation.

Imaging of pulmonary fibrosis in children: A review, with proposed diagnostic criteria.

Computed tomography (CT) imaging findings of pulmonary fibrosis are well established for adults and have been shown to correlate with prognosis and outcome. Recognition of fibrotic CT findings in children is more limited. With approved treatments for adult pulmonary fibrosis, it has become critical to define CT criteria for fibrosis in children, to identify patients in need of treatment and those eligible for clinical trials. Understanding how pediatric fibrosis compares with idiopathic pulmonary fibrosis and other causes of fibrosis in adults is increasingly important as these patients transition to adult care teams. Here, we review what is known regarding the features of pulmonary fibrosis in children compared with adults. Pulmonary fibrosis in children may be associated with genetic surfactant dysfunction disorders, autoimmune systemic disorders, and complications after radiation, chemotherapy, transplantation, and other exposures. Rather than a basal-predominant usual interstitial pneumonia pattern with honeycombing, pediatric fibrosis is primarily characterized by reticulation, traction bronchiectasis, architectural distortion, or cystic lucencies/abnormalities. Ground-glass opacities are more frequent in children with fibrotic interstitial lung disease than adults, and disease distribution appears more diffuse, without clearly defined axial or craniocaudal predominance. Following discussion and consensus amongst a panel of expert radiologists, pathologists and physicians, distinctive disease features were integrated to develop criteria for the first global Phase III trial in children with pulmonary fibrosis.

Estimating the effect of nintedanib on forced vital capacity in children and adolescents with fibrosing interstitial lung disease using a Bayesian dynamic borrowing approach.

BACKGROUND: The rarity of childhood interstitial lung disease (chILD) makes it challenging to conduct powered trials. In the InPedILD trial, among 39 children and adolescents with fibrosing ILD, there was a numerical benefit of nintedanib versus placebo on change in forced vital capacity (FVC) over 24 weeks (difference in mean change in FVC % predicted of 1.21 [95% confidence interval: -3.40, 5.81]). Nintedanib has shown a consistent effect on FVC across populations of adults with different diagnoses of fibrosing ILD. METHODS: In a Bayesian dynamic borrowing analysis, prespecified before data unblinding, we incorporated data on the effect of nintedanib in adults and the data from the InPedILD trial to estimate the effect of nintedanib on FVC in children and adolescents with fibrosing ILD. The data from adults were represented as a meta-analytic predictive (MAP) prior distribution with mean 1.69 (95% credible interval: 0.49, 3.08). The adult data were weighted according to expert judgment on their relevance to the efficacy of nintedanib in chILD, obtained in a formal elicitation exercise. RESULTS: Combined data from the MAP prior and InPedILD trial analyzed within the Bayesian framework resulted in a median difference between nintedanib and placebo in change in FVC % predicted at Week 24 of 1.63 (95% credible interval: -0.69, 3.40). The posterior probability for superiority of nintedanib versus placebo was 95.5%, reaching the predefined success criterion of at least 90%. CONCLUSION: These findings, together with the safety data from the InPedILD trial, support the use of nintedanib in children and adolescents with fibrosing ILDs.

Cardiopulmonary Phenotypes and Protein Signatures in Children With Down Syndrome.

Pulmonary disease, lower respiratory tract infection, and pneumonia are the largest causes of morbidity and mortality in individuals with Down syndrome (DS), but whether pulmonary diagnoses in children with DS are common and occur independently of cardiac disease and pulmonary hypertension (PH) is unknown. Cardiopulmonary phenotypes were examined in a cohort of 1248 children with DS. Aptamer-based proteomic analysis of blood was performed in a subset (n = 120) of these children. By the age of 10 years, half of the patients in this cohort (n = 634, 50.8%) had co-occurring pulmonary diagnoses. That proteins and related pathways were distinct between children with pulmonary diagnoses and those with cardiac disease and/or PH may indicate that pulmonary diagnoses appear to occur independently of cardiac disease and PH. Heparin sulfate-glycosaminoglycandegradation, nicotinate metabolism, and elastic fiber formation were ranked highest in the group with pulmonary diagnoses.

Defining and Promoting Pediatric Pulmonary Health: Assessing Lung Function and Structure.

Lifelong respiratory health is rooted in the structural and functional development of the respiratory system in early life. Exposures and interventions antenatally through childhood can influence lung development into young adulthood, the life stage with the highest achievable lung function. Because early respiratory health sets the stage for adult lung function trajectories and risk of developing chronic obstructive pulmonary disease, understanding how to promote lung health in children will have far reaching personal and population benefits. To achieve this, it is critical to have accurate and precise measures of structural and functional lung development that track throughout life stages. From this foundation, evaluation of environmental, genetic, metabolic, and immune mechanisms involved in healthy lung development can be investigated. These goals require the involvement of general pediatricians, pediatric subspecialists, patients, and researchers to design and implement studies that are broadly generalizable and applicable to otherwise healthy and chronic disease populations. This National Institutes of Health workshop report details the key gaps and opportunities regarding lung function and structure.

Pediatric Aerodigestive Medicine: Advancing Collaborative Care for Children With Oropharyngeal Dysphagia.

OBJECTIVES: Aerodigestive disorders encompass various pathological conditions affecting the lungs, upper airway, and gastrointestinal tract in children. While advanced care has primarily occurred in specialty centers, many children first present to general pediatric gastroenterologists with aerodigestive symptoms necessitating awareness of these conditions. At the 2021 Annual North American Society for Pediatric Gastroenterology, Hepatology and Nutrition meeting, the aerodigestive Special Interest Group held a full-day symposium entitled, Pediatric Aerodigestive Medicine: Advancing Collaborative Care of Children with Aerodigestive Disorders. The symposium aimed to underline the significance of a multidisciplinary approach to achieve better outcomes for these complex patients. METHODS: The symposium brought together leading experts to highlight the growing aerodigestive field, promote new scientific and therapeutic strategies, share the structure and benefits of a multidisciplinary approach in diagnosing common and rare aerodigestive disorders, and foster multidisciplinary discussion of complex cases while highlighting the range of therapeutic and diagnostic options. In this article, we showcase the diagnostic and therapeutic approach to oropharyngeal dysphagia (OPD), one of the most common aerodigestive conditions, emphasizing the role of a collaborative model. CONCLUSIONS: The aerodigestive field has made significant progress and continues to grow due to a unique multidisciplinary, collaborative model of care for these conditions. Despite diagnostic and therapeutic challenges, the multidisciplinary approach has enabled and greatly improved efficient, high-quality, and evidence-based care for patients, including those with OPD.

Advancements in imaging in ChILD.

Interstitial and diffuse lung diseases in children constitute a range of congenital and acquired disorders. These disorders present with signs and symptoms of respiratory disease accompanied by diffuse radiographic changes. In many cases, radiographic findings are nonspecific, while in other disorders, chest computed tomography (CT) is diagnostic in the appropriate context. Regardless, chest imaging remains central in the evaluation of the patient with suspected childhood interstitial lung disease (chILD). Several newly described chILD entities, spanning both genetic and acquired etiologies, have imaging that aid in their diagnoses. Advances in CT scanning technology and CT analysis techniques continue to improve scan quality as well as expand use of chest CT as a research tool. Finally, ongoing research is expanding use of imaging modalities without ionizing radiation. Magnetic resonance imaging is being applied to investigate pulmonary structure and function, and ultrasound of the lung and pleura is a novel technique with an emerging role in chILD disorders. This review describes the current state of imaging in chILD including recently described diagnoses, advances in conventional imaging techniques and applications, and evolving new imaging modalities that expand the clinical and research roles for imaging in these disorders.

Social support moderates the relationship between burnout and job satisfaction in aerodigestive team members.

OBJECTIVES: Burnout among healthcare workers is a public health crisis. Burnout is associated with elevated cynicism, emotional exhaustion, and low job satisfaction. Methods to combat burnout have been challenging to identify. Based on positive experiences of pediatric aerodigestive team members, we hypothesized that social support in multidisciplinary aerodigestive teams moderates the effects of burnout on job satisfaction. METHODS: Using a survey of the Aerodigestive Society, members of Aerodigestive teams (N = 119) completed demographics, the Maslach Burnout Inventory, and measures of job satisfaction, emotional, and instrumental social support. In addition to assessing relationships between components of burnout and job satisfaction, six tests were conducted using PROCESS to ascertain the degree to which social support moderated these relationships. RESULTS: Similar to US healthcare base rates, burnout scores in this sample suggest that a third-to-half felt Emotionally Exhausted and Burned Out from work "A few times a month"-to-"Every Day." Simultaneously, however, the majority in sample (60.6%) noted feeling that they "positively impact others' lives" with 33.3% endorsing "Every Day." Job satisfaction was strikingly high at 89%, with most reporting Aerodigestive team affiliation related to higher job satisfaction. Both Emotional and Instrumental social support moderated the effect of Cynicism and Emotional Exhaustion on Job Satisfaction, with higher Job Satisfaction scores in conditions of high support. CONCLUSIONS: These results support the hypothesis that social support from a multidisciplinary aerodigestive team moderates the effect of burnout in its team members. Further work is needed to understand if membership in other interprofessional healthcare teams can help combat the negative effects of burnout.

Feeding and Swallowing Characteristics of Children With Esophageal Atresia and Tracheoesophageal Fistula.

OBJECTIVES: This study aimed to characterize feeding/swallowing difficulties in children with esophageal atresia and/or tracheoesophageal fistula (EA/TEF) and evaluate associations among feeding difficulties, pharyngeal dysphagia (PD), and other aerodigestive evaluation findings. METHODS: This was a retrospective cohort study of feeding/swallowing characteristics of 44 patients with EA/TEF treated in the aerodigestive program of a single academic medical institution from 2010 to 2015. Demographics, comorbidities, presence and characteristics of feeding/swallowing difficulties, and results of relevant diagnostic tests [videofluoroscopic swallow studies (VFSS), clinical feeding evaluations (CFEs), chest computerized tomography (CT) scans, pulmonary bronchoscopies, and upper GI (UGI)/esophagrams] were reviewed. RESULTS: Fifty percent of the cohort had PD and 88.6% had feeding difficulties. Across 118 encounters (87 VFSS and 31 CFEs), feeding difficulties suggestive of esophageal dysphagia were most frequently seen in children over 48 months and feeding difficulties suggestive of developmental feeding problems were most frequently seen in children from 24 to 48 months. Abnormal findings were present in 59.8% of VFSS, with aspiration (34.5%) and pharyngeal residue (26.4%) the most frequently observed signs of dysphagia. Abnormal UGI/esophagram findings were not associated with significantly increased risk of feeding difficulties during visits within 3 months (risk ratio, RR = 1.33). Presence of dysphagia was associated with increased risk for some abnormal CT findings (RR= 3.0 for airspace and 3.0 for bronchiectasis). CONCLUSIONS: Feeding/swallowing difficulties are common in EA/TEF, and types of feeding difficulties vary by patient age. The presence of abnormal findings on UGI/esophagram did not increase the risk of feeding complaints; however, the presence of dysphagia increased the risk of abnormal chest CT.

Nintedanib in children and adolescents with fibrosing interstitial lung diseases.

BACKGROUND: Childhood interstitial lung disease (ILD) comprises a spectrum of rare ILDs affecting infants, children and adolescents. Nintedanib is a licensed treatment for pulmonary fibrosis in adults. The primary objectives of the InPedILD trial were to determine the dose-exposure and safety of nintedanib in children and adolescents with fibrosing ILD. METHODS: Patients aged 6-17 years with fibrosing ILD on high-resolution computed tomography and clinically significant disease were randomised 2:1 to receive nintedanib or placebo for 24 weeks and then open-label nintedanib. Dosing was based on weight-dependent allometric scaling. Co-primary end-points were the area under the plasma concentration-time curve at steady state (AUCτ,ss) at weeks 2 and 26 and the proportion of patients with treatment-emergent adverse events at week 24. RESULTS: 26 patients received nintedanib and 13 patients received placebo. The geometric mean (geometric coefficient of variation) AUCτ,ss for nintedanib was 175 µg·h·L-1 (85.1%) in patients aged 6-11 years and 160 µg·h·L-1 (82.7%) in patients aged 12-17 years. In the double-blind period, adverse events were reported in 84.6% of patients in each treatment group. Two patients discontinued nintedanib due to adverse events. Diarrhoea was reported in 38.5% and 15.4% of the nintedanib and placebo groups, respectively. Adjusted mean±se changes in percentage predicted forced vital capacity at week 24 were 0.3±1.3% in the nintedanib group and -0.9±1.8% in the placebo group. CONCLUSIONS: In children and adolescents with fibrosing ILD, a weight-based dosing regimen resulted in exposure to nintedanib similar to adults and an acceptable safety profile. These data provide a scientific basis for the use of nintedanib in this patient population.

Effects of ivacaftor on systemic inflammation and the plasma proteome in people with CF and G551D.

BACKGROUND: Ivacaftor is a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator for people with CF and the G551D mutation. We aimed to investigate the biology of CFTR modulation and systemic effects of CFTR restoration by examining changes in circulating measurements of inflammation and growth and novel proteins with ivacaftor treatment. METHODS: Blood samples from 64 CF subjects with G551D-CFTR were analyzed for inflammatory and growth-related proteins at baseline, 1 and 6 months after ivacaftor initiation. In 30 subjects, plasma was assayed for 1,322 proteins using the SomaScan proteomic platform at baseline and 6 months post-ivacaftor. Correlations with clinical outcomes were assessed. MEASUREMENTS AND MAIN RESULTS: Significant reductions in high mobility group box-1 protein (HMGB-1), calprotectin, serum amyloid A, and granulocyte colony-stimulating factor (G-CSF), and an increase in insulin-like growth factor (IGF-1) occurred 1 month after ivacaftor. This treatment effect was sustained at 6 months for HMGB-1 and calprotectin. Correcting for multiple comparisons in the proteomic analysis, 9 proteins (albumin, afamin, leptin, trypsin, pancreatic stone protein [PSP], pituitary adenylate cyclase-activating polypeptide-38, repulsive guidance molecule A [RGMA], calreticulin, GTPase KRas) changed significantly with ivacaftor. Proteins changing with treatment are involved in lipid digestion and transport and extracellular matrix organization biological processes. Reductions in calprotectin and G-CSF and increases in calreticulin, and RGMA correlated with improved lung function, while increasing IGF-1, leptin and afamin and decreasing PSP correlated with increased weight. CONCLUSIONS: Ivacaftor led to changes in inflammatory, lipid digestion, and extracellular matrix proteins, lending insights into the extrapulmonary effects of CFTR modulation.

Clinical characteristics of people with cystic fibrosis and frequent fungal infection.

BACKGROUND: Individuals with cystic fibrosis (CF) and fungal airway infection may present with fungal bronchitis, allergic bronchopulmonary aspergillosis (ABPA) or may appear unaffected despite fungal detection. We sought to characterize people with CF with frequent detection of fungi from airway samples and determine clinical outcomes. METHODS: This retrospective study included individuals with CF with ≥4 lower airway cultures over a 2-year baseline period and ≥2 years of follow-up. We defined two groups: ≤1 positive fungus culture (rare) or ≥2 positive cultures during baseline (frequent). Clinical characteristics and outcomes were determined. RESULTS: Between 2004 and 2016, 294 individuals met inclusion with 62% classified as rare and 38% as frequent fungi during baseline. Median follow-up was 6 years (range: 2-9 years). Aspergillus fumigatus was the most common fungal species detected. Individuals with frequent fungi were older (13.7 vs. 11.7 years, p = .02) and more likely to have Stenotrophomonas maltophilia (35% vs. 17%, p < .001) at baseline, but did not differ in lung function or ABPA diagnosis. During follow-up, those with frequent fungi were more likely to have chronic Pseudomonas aeruginosa and S. maltophilia. Individuals with ABPA and frequent fungi had the highest rates of co-infection and co-morbidities, and a trend towards more rapid lung function decline. DISCUSSION: Fungal infection in CF was associated with frequent P. aeruginosa and S. maltophilia co-infection even in those without ABPA. Individuals with frequent fungi and ABPA had worse outcomes, highlighting the potential contribution of fungi to CF pulmonary disease.

Airwave oscillometry to measure lung function in children with Down syndrome.

BACKGROUND: Children with Down syndrome are at risk for significant pulmonary co-morbidities, including recurrent respiratory infections, dysphagia, obstructive sleep apnea, and pulmonary vascular disease. Because the gold standard metric of lung function, spirometry, may not be feasible in children with intellectual disabilities, we sought to assess the feasibility of both airwave oscillometry and spirometry in children with Down syndrome. METHODS: Thirty-four children with Down syndrome aged 5-17 years were recruited. Participants performed airwave oscillometry and spirometry before and 10 min after albuterol. Outcomes include success rates, airway resistance and reactance pre- and post-bronchodilator, and bronchodilator response. RESULTS: Participants were median age 9.2 years (interquartile range 7.2, 12.0) and 47% male. Airwave oscillometry was successful in 26 participants (76.5%) and 4 (11.8%) were successful with spirometry. No abnormalities in airway resistance were detected, and 16/26 (61.5%) had decreased reactance. A positive bronchodilator response by oscillometry was observed in 5/23 (21.7%) of those with successful pre- and post-bronchodilator testing. CONCLUSIONS: Measures of pulmonary function were successfully obtained using airwave oscillometry in children with Down syndrome, which supports its use in this high-risk population. IMPACT: Children with Down syndrome are at risk for significant pulmonary co-morbidities, but the gold standard metric of lung function, spirometry, may not be feasible in children with intellectual disabilities. This may limit the population's enrollment in clinical trials and in standardized clinical care. In this prospective study of lung function in children with Down syndrome, airwave oscillometry was successful in 76% of participants but spirometry was successful in only 12%. This study reinforces that measures of pulmonary function can be obtained successfully using airwave oscillometry in children with Down syndrome, which supports its use in this high-risk population.

Delivery and actuation of aerosolized microbots.

For disease of the lung, the physical key to effective inhalation-based therapy is size; too large (10's of µm) and the particles or droplets do not remain suspended in air to reach deep within the lungs, too small (subµm) and they are simply exhaled without deposition. µBots within this ideal low-µm size range however are challenging to fabricate and would lead to devices that lack the speed and power necessary for performing work throughout the pulmonary network. To uncouple size from structure and function, here we demonstrate an approach where individual building blocks are aerosolized and subsequently assembled in situ into µbots capable of translation, drug delivery, and mechanical work deep within lung mimics. With this strategy, a variety of pulmonary diseases previously difficult to treat may now be receptive to µbot-based therapies.

Electrical impedance tomography detects changes in ventilation after airway clearance in spinal muscular atrophy type I.

The effect of mechanical insufflation-exsufflation (MIE) for airway clearance in patients with spinal muscular atrophy type I (SMA-I) on the distribution of ventilation in the lung is unknown, as is the duration of its beneficial effects. A pilot study to investigate the feasibility of using three dimensional (3-D) electrical impedance tomography (EIT) images to estimate lung volumes pre- and post-MIE for assessing the effectiveness of mechanical insufflation-exsufflation (MIE) was conducted in 6 pediatric patients with SMA-I in the neuromuscular clinic at Children's Hospital Colorado. EIT data were collected before, during, and after the MIE procedure on two rows of 16 electrodes placed around the chest. Lung volumes were computed from the images and compared before, during, and after the MIE procedure to assess the ability of EIT to estimate changes in lung volume during insufflation and exsufflation. Images of pulsatile pulmonary perfusion were computed in subjects able to perform breath-holding. In four of the six subjects, lung volumes during tidal breathing increased after MIE (average change from pre to post MIE was 58.8±55.1 mL). The time-dependent plots of lung volume computed from the EIT data clearly show when the MIE device insufflates and exsufflates air and the rest periods between mechanical coughs. Images of pulmonary pulsatile perfusion were computed from data collected during breathing pauses. The results suggest that EIT holds promise for estimating lung volumes and ventilation/perfusion mismatch, both of which are useful for assessing the effectiveness of MIE in clearing mucus plugs.

Airway obstruction and inflammation on combined bronchoscopy in children with Down syndrome.

OBJECTIVE: To characterize the upper and lower airway findings in children with Down syndrome and chronic respiratory symptoms, based on evaluation by flexible bronchoscopy (FB) with bronchoalveolar lavage and microlaryngoscopy with bronchoscopy (MLB). STUDY DESIGN: A retrospective review was conducted of children with Down syndrome aged 1 month to 17 years, who underwent both FB and MLB within a 1-year timeframe between 2010 and 2019 at Children's Hospital Colorado. Anatomic airway findings are reported as frequencies within the cohort. Bronchoalveolar lavage fluid (BALF) culture results, cell differential, and cytopathology are reported as frequencies or mean ± standard deviation. BALF results were compared between children with and without dysphagia documented on a recent swallow evaluation. RESULTS: Overall, 168 children with Down syndrome were included, with median age of 2.1 years (interquartile range: 0.9-5.1 years). At least one abnormal airway finding was recorded in 96% of patients and 46% had at least three abnormal findings. The most common findings included tracheomalacia (39% FB; 37% MLB), subglottic stenosis (35% MLB), pharyngomalacia (32% FB), and laryngomalacia (16% FB; 30% MLB). Comparison of BALF based on dysphagia status showed that children with dysphagia had more frequent cultures positive for mixed upper respiratory flora (76% vs. 47%, p = 0.004) and a higher percentage of neutrophils (20% vs. 7%, p = 0.006). CONCLUSION: Abnormal findings for FB and MLB are common in children with Down syndrome and chronic respiratory symptoms, and performing the procedures together may increase the diagnostic yield.

Study design of a randomised, placebo-controlled trial of nintedanib in children and adolescents with fibrosing interstitial lung disease.

Childhood interstitial lung disease (chILD) comprises >200 rare respiratory disorders, with no currently approved therapies and variable prognosis. Nintedanib reduces the rate of forced vital capacity (FVC) decline in adults with progressive fibrosing interstitial lung diseases (ILDs). We present the design of a multicentre, prospective, double-blind, randomised, placebo-controlled clinical trial of nintedanib in patients with fibrosing chILD (1199-0337 or InPedILD; ClinicalTrials.gov: NCT04093024). Male or female children and adolescents aged 6-17 years (≥30; including ≥20 adolescents aged 12-17 years) with clinically significant fibrosing ILD will be randomised 2:1 to receive oral nintedanib or placebo on top of standard of care for 24 weeks (double-blind), followed by variable-duration nintedanib (open-label). Nintedanib dosing will be based on body weight-dependent allometric scaling, with single-step dose reductions permitted to manage adverse events. Eligible patients will have evidence of fibrosis on high-resolution computed tomography (within 12 months of their first screening visit), FVC ≥25% predicted, and clinically significant disease (Fan score of ≥3 or evidence of clinical progression over time). Patients with underlying chronic liver disease, significant pulmonary arterial hypertension, cardiovascular disease, or increased bleeding risk are ineligible. The primary endpoints are pharmacokinetics and the proportion of patients with treatment-emergent adverse events at week 24. Secondary endpoints include change in FVC% predicted from baseline, Pediatric Quality of Life Questionnaire, oxygen saturation, and 6-min walk distance at weeks 24 and 52. Additional efficacy and safety endpoints will be collected to explore long-term effects.

Lung inflammation and simulated airway resistance in infants with cystic fibrosis.

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.

Jet flow rate and needle position govern distal airway pressures during low-frequency jet ventilation.

OBJECTIVES: Although jet ventilation is frequently used during surgery for airway stenosis, little is known about distal airway pressures during jet ventilation. The objective of the study is to determine how jet pressure, flow rate, and position of the ventilation needle relate to distal airway pressure magnitude and homogeneity. METHODS: Two 3D models of the first five generations of the human airway tree were created. One is a duplicate of a human airway from a 15-year-old healthy male's computed tomography scan, and the other is an idealized symmetric model of human lung morphometry. Pressure transducers measured fifth-generation distal airway pressures in both models. A computer-controlled jet needle positioning system was used to ventilate the lung casts. The effects of jet needle position, jet pressure, and jet flow rate on distal airway pressure and homogeneity were measured. RESULTS: Total entrained jet flow rate was the most reliable predictor of distal airway pressure. Pressure supplied to the jet ventilation needle had a positive linear relationship with distal airway pressure; however, this relationship was dependent on the jet needle flow resistance. As the ventilation needle moved closer to the tracheal wall, ventilation homogeneity decreased. Depth into the trachea was positively correlated with sensitivity of the needle to the tracheal wall. CONCLUSION: In this model, total entrained jet flow rate is a more robust predictor of distal airway pressure than jet inlet pressure. More homogeneous ventilation was observed in our model with the ventilation needle centered in the proximal region of the trachea.