American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Apr 2021
Comparative StudyAirspace Macrophages and Monocytes Exist in Transcriptionally Distinct Subsets in Healthy Adults.
Rationale: Macrophages are the most abundant immune cell in the alveoli and small airways and are traditionally viewed as a homogeneous population during health. Whether distinct subsets of airspace macrophages are present in healthy humans is unknown. Single-cell RNA sequencing allows for examination of transcriptional heterogeneity between cells and between individuals. ⋯ Resident macrophages make up the largest population and include novel subsets defined by inflammatory and metal-binding profiles. Monocyte-like cells within the airspaces are transcriptionally aligned with circulating blood cells and include a rare population defined by expression of cell-matrix interaction genes. This study is the first to delineate the conserved heterogeneity of airspace immune cells during health and identifies two previously unrecognized macrophage subsets.
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Am. J. Respir. Crit. Care Med. · Apr 2021
Transmission of Oscillatory Volumes into the Preterm Lung during Noninvasive High-Frequency Ventilation.
Rationale: There is increasing evidence for a clinical benefit of noninvasive high-frequency oscillatory ventilation (nHFOV) in preterm infants. However, it is still unknown whether the generated oscillations are effectively transmitted to the alveoli. Objectives: To assess magnitude and regional distribution of oscillatory volumes (VOsc) at the lung level. ⋯ Conclusions: In preterm infants, VOsc during nHFOV are transmitted to the lung. Compared with the regional distribution of tidal breaths, oscillations preferentially reach the right and non-gravity-dependent lung. These data increase our understanding of the physiological processes underpinning nHFOV and may lead to further refinement of this novel technique.
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Am. J. Respir. Crit. Care Med. · Apr 2021
Role of PEEP and Regional Transpulmonary Pressure in Asymmetrical Lung Injury.
Rationale: Asymmetrical lung injury is a frequent clinical presentation. Regional distribution of Vt and positive end-expiratory pressure (PEEP) could result in hyperinflation of the less-injured lung. The validity of esophageal pressure (Pes) is unknown. ⋯ Driving transpulmonary pressure is similar for both lungs. Vt distribution results from regional respiratory system compliance. Moderate PEEP homogenizes Vt distribution between lungs without generating hyperinflation.