RATIONALE The respiratory mechanisms of a successful transition of preterm infants after birth are largely unknown. OBJECTIVES To describe intrapulmonary gas flows during different breathing patterns directly after birth Methods: Analysis of electrical impedance tomography (EIT) data from a previous randomized trial in preterm infants 26-32 weeks gestational age. EIT data for individual breaths were extracted and lung volumes as well as ventilation distribution were calculated for end of inspiration, end of expiratory braking/holding manoeuvre and end of expiration. MEASUREMENTS AND MAIN RESULTS Overall, 10'348 breaths in 33 infants were analysed. We identified three distinct breath types within the first ten minutes after birth: tidal breathing (44% of all breaths; sinusoidal breathing without expiratory disruption), braking (50%; expiratory brake with a short duration) and holding (6%; expiratory brake with a long duration). Only after holding breaths, end-expiratory lung volume increased [median (IQR) 2.0 (0.6 to 4.3) AU/kg vs 0.0 (-1.0 to 1.1) vs 0.0 (-1.1 to 0.4), p<0.001]. This was mediated by intrathoracic air redistribution to the left and non-gravity-dependent parts of the lung via pendelluft gas flows during braking/holding manoeuvres. CONCLUSIONS Respiratory transition in preterm infants is characterized by unique breathing patterns. Holding breaths contribute to early lung aeration after birth in preterm infants. This is facilitated by air redistribution during braking/holding manoeuvres via pendelluft flow which may prevent lung liquid reflux in this highly adaptive situation. This study deciphers mechanisms for a successful foetal-to-neonatal transition and increases our pathophysiological understanding of this unique moment in life.

中文翻译：

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破译极早产儿呼吸胎儿到新生儿转变的机制。

基本原理 早产儿出生后成功过渡的呼吸机制在很大程度上尚不清楚。目的 描述出生后不同呼吸模式下的肺内气流 方法：分析先前针对 26-32 周胎龄早产儿的随机试验的电阻抗断层扫描 (EIT) 数据。提取各个呼吸的 EIT 数据，并计算吸气末、呼气制动/保持动作末和呼气末的肺容量和通气分布。测量和主要结果 总体而言，分析了 33 名婴儿的 10,348 次呼吸。我们在出生后的前十分钟内确定了三种不同的呼吸类型：潮式呼吸（占所有呼吸的 44%；没有呼气中断的正弦呼吸）、制动（50%；持续时间短的呼气制动）和保持（6%；呼气制动）且持续时间较长）。仅在屏住呼吸后，呼气末肺容量增加[中位 (IQR) 2.0（0.6 至 4.3）AU/kg vs 0.0（-1.0 至 1.1）vs 0.0（-1.1 至 0.4），p<0.001]。这是通过制动/保持动作期间胸腔内空气通过 Pendelluft 气流重新分配到肺部的左侧和非重力依赖部分来介导的。结论 早产儿呼吸转变的特点是独特的呼吸模式。屏住呼吸有助于早产儿出生后早期肺部通气。这是通过在制动/保持操作期间通过pendelluft流进行的空气重新分配来促进的，这可以在这种高度适应性的情况下防止肺液体回流。这项研究破译了胎儿到新生儿成功过渡的机制，并增加了我们对生命中这一独特时刻的病理生理学理解。