Partitioning mechanics in of airway and parenchymal unsedated newborn infants

The recent trend toward development of noninvasive methods that can accurately evaluate the lung periphery has particular relevance for the predominantly parenchymal nature of neonatal respiratory disease. Concerns regarding the safety of sedating newborn (especially preterm) infants have also stimulated a drive toward measurements obtained during natural sleep. This study aimed to adapt existing methodology for the low-frequency forced oscillation technique to obtain partitioned measurements of airway and parenchymal mechanics during unsedated, quiet sleep in newborn infants without a history of previous respiratory disease. A face mask was positioned over the infant's mouth and nose and a brief (4-5 s) breathing pause was induced by evoking the Hering-Breuer reflex via end-inspiratory occlusion at raised lung volume (airway opening occluded at 2 kPa). Airway opening pressure and flow were measured while a pseudorandom noise (2-14 Hz) was applied to the airway. Acceptable pulmonary impedance data were collected in 11 of the 12 infants studied (34.1-42.6 wk postmenstrual age, 1.9-3.9 kg body weight) on 17 (total of 20) occasions. Airway parameters (resistance and inertance) and respiratory tissue parameters were calculated from the resultant impedance spectra. Tissue resistance and tissue elastance decreased with increasing body length albeit at different rates such that hysteresivity (tissue resistance/ tissue elastance) also decreased. There was a trend toward reduction in airway resistance with increasing length. Measurements of lung function are feasible in the unsedated newborn infant using low-frequency forced oscillations and confirm the important contribution of tissue resistance to lung mechanics in the developing lung

Association of Adenotonsillectomy with Asthma Outcomes in Children: A Longitudinal Database Analysis

<div><p>Background</p><p>Childhood asthma and obstructive sleep apnea (OSA), both disorders of airway inflammation, were associated in recent observational studies. Although childhood OSA is effectively treated by adenotonsillectomy (AT), it remains unclear whether AT also improves childhood asthma. We hypothesized that AT, the first line of therapy for childhood OSA, would be associated with improved asthma outcomes and would reduce the usage of asthma therapies in children.</p><p>Methods and Findings</p><p>Using the 2003–2010 MarketScan database, we identified 13,506 children with asthma in the United States who underwent AT. Asthma outcomes during 1 y preceding AT were compared to those during 1 y following AT. In addition, 27,012 age-, sex-, and geographically matched children with asthma without AT were included to examine asthma outcomes among children without known adenotonsillar tissue morbidity. Primary outcomes included the occurrence of a diagnostic code for acute asthma exacerbation (AAE) or acute status asthmaticus (ASA). Secondary outcomes included temporal changes in asthma medication prescriptions, the frequency of asthma-related emergency room visits (ARERs), and asthma-related hospitalizations (ARHs). Comparing the year following AT to the year prior, AT was associated with significant reductions in AAE (30.2%; 95% CI: 25.6%–34.3%; <i>p</i><0.0001), ASA (37.9%; 95% CI: 29.2%–45.6%; <i>p</i><0.0001), ARERs (25.6%; 95% CI: 16.9%–33.3%; <i>p</i><0.0001), and ARHs (35.8%; 95% CI: 19.6%–48.7%; <i>p</i> = 0.02). Moreover, AT was associated with significant reductions in most asthma prescription refills, including bronchodilators (16.7%; 95% CI: 16.1%–17.3%; <i>p</i><0.001), inhaled corticosteroids (21.5%; 95% CI: 20.7%–22.3%; <i>p</i><0.001), leukotriene receptor antagonists (13.4%; 95% CI: 12.9%–14.0%; <i>p</i><0.001), and systemic corticosteroids (23.7%; 95% CI: 20.9%–26.5%; <i>p</i><0.001). In contrast, there were no significant reductions in these outcomes in children with asthma who did not undergo AT over an overlapping follow-up period. Limitations of the MarketScan database include lack of information on race and obesity status. Also, the MarketScan database does not include information on children with public health insurance (i.e., Medicaid) or uninsured children.</p><p>Conclusions</p><p>In a very large sample of privately insured children, AT was associated with significant improvements in several asthma outcomes. Contingent on validation through prospectively designed clinical trials, this study supports the premise that detection and treatment of adenotonsillar tissue morbidity may serve as an important strategy for improving asthma control.</p><p><i>Please see later in the article for the Editors' Summary</i></p></div

Evaluation of Respiratory Impedance in Asthma and COPD by an Impulse Oscillation System

Objective The purpose of this study was to clarify the differences in physiological properties of the airways between asthma and COPD using an impulse oscillation system (IOS). Patients and Methods Subjects comprised 95 stable COPD patients, 52 never-smoker asthma patients and 29 healthy never-smokers > 60 years old, all matched for age, in whom respiratory impedance was examined by IOS. Results In both asthma and COPD patients, a significant increase in respiratory resistance (Rrs5) and more negative value of respiratory reactance (Xrs5) at 5 Hz of oscillatory frequency with an increase in resonant frequency (fres) were observed when compared with healthy never-smokers. In asthma, a significant increase in respiratory resistance at 20 Hz (Rrs20) was also observed when compared with healthy never-smokers and COPD. The increases in Rrs5 and relative changes of Xrs5 to more negative were remarkable with increasing severity of COPD. On the other hand, among patients with asthma, these changes in Rrs5 and Xrs5 were also observed in asthmatics with normal FEV1/FVC. Interestingly, Xrs5 showed further changes to more negative in expiration of tidal breath in severe COPD, whereas no significant changes in Xrs5 to more negative in expiration was observed in healthy never-smokers and asthmatics with and without normal FEV1/FVC. Conclusion IOS may be useful for detecting pathophysiological changes of respiratory system in accordance with severity of COPD and even in asthmatics with normal FEV1/FVC. The larger within-breath changes of Xrs5 to more negative in severe COPD may represent easy collapsibility of small airways in expiration of tidal breath. These properties may help to analyze airway mechanics and to identify abnormalities of the airways that cannot be found by spirometry alone.ArticleINTERNAL MEDICINE. 49(1):23-30 (2010)journal articl