1. Spatiotemporal Aeration and Lung Injury Patterns Are Influenced by the First Inflation Strategy at Birth.
- Author
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Tingay DG, Rajapaksa A, Zonneveld CE, Black D, Perkins EJ, Adler A, Grychtol B, Lavizzari A, Frerichs I, Zahra VA, and Davis PG
- Subjects
- Animals, Animals, Newborn, Biomarkers metabolism, Disease Models, Animal, Early Growth Response Protein 1 genetics, Early Growth Response Protein 1 metabolism, Gene Expression Regulation, Lung diagnostic imaging, Lung metabolism, Lung Compliance, Lung Volume Measurements, Pressure, Pulmonary Gas Exchange, Pulmonary Ventilation, RNA, Messenger metabolism, Respiratory Mechanics, Risk Factors, Sheep, Tidal Volume, Time Factors, Tomography, X-Ray Computed, Ventilator-Induced Lung Injury diagnostic imaging, Ventilator-Induced Lung Injury genetics, Ventilator-Induced Lung Injury metabolism, Ventilator-Induced Lung Injury physiopathology, Lung physiopathology, Positive-Pressure Respiration adverse effects, Ventilator-Induced Lung Injury etiology
- Abstract
Ineffective aeration during the first inflations at birth creates regional aeration and ventilation defects, initiating injurious pathways. This study aimed to compare a sustained first inflation at birth or dynamic end-expiratory supported recruitment during tidal inflations against ventilation without intentional recruitment on gas exchange, lung mechanics, spatiotemporal regional aeration and tidal ventilation, and regional lung injury in preterm lambs. Lambs (127 ± 2 d gestation), instrumented at birth, were ventilated for 60 minutes from birth with either lung-protective positive pressure ventilation (control) or as per control after either an initial 30 seconds of 40 cm H2O sustained inflation (SI) or an initial stepwise end-expiratory pressure recruitment maneuver during tidal inflations (duration 180 s; open lung ventilation [OLV]). At study completion, molecular markers of lung injury were analyzed. The initial use of an OLV maneuver, but not SI, at birth resulted in improved lung compliance, oxygenation, end-expiratory lung volume, and reduced ventilatory needs compared with control, persisting throughout the study. These changes were due to more uniform inter- and intrasubject gravity-dependent spatiotemporal patterns of aeration (measured using electrical impedance tomography). Spatial distribution of tidal ventilation was more stable after either recruitment maneuver. All strategies caused regional lung injury patterns that mirrored associated regional volume states. Irrespective of strategy, spatiotemporal volume loss was consistently associated with up-regulation of early growth response-1 expression. Our results show that mechanical and molecular consequences of lung aeration at birth are not simply related to rapidity of fluid clearance; they are also related to spatiotemporal pressure-volume interactions within the lung during inflation and deflation.
- Published
- 2016
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