Tingay David G, Naidu Hannah, Tingay Hamish D, Pereira-Fantini Prue M, Kneyber Martin C J, Becher Tobias
Neonatal Research, Murdoch Children's Research Institute, Parkville, Australia.
Department of Paediatrics, University of Melbourne, Melbourne, Australia.
Intensive Care Med Exp. 2023 May 22;11(1):28. doi: 10.1186/s40635-023-00511-9.
Mechanical power is a major contributor to lung injury and mortality in adults receiving mechanical ventilation. Recent advances in our understanding of mechanical power have allowed the different mechanical components to be isolated. The preterm lung shares many of the same similarities that would indicate mechanical power may be relevant in this group. To date, the role of mechanical power in neonatal lung injury is unknown. We hypothesise that mechanical power maybe useful in expanding our understanding of preterm lung disease. Specifically, that mechanical power measures may account for gaps in knowledge in how lung injury is initiated.
HYPOTHESIS-GENERATING DATA SET: To provide a justification for our hypothesis, data in a repository at the Murdoch Children's Research Institute, Melbourne (Australia) were re-analysed. 16 preterm lambs 124-127d gestation (term 145d) who received 90 min of standardised positive pressure ventilation from birth via a cuffed endotracheal tube were chosen as each was exposed to three distinct and clinically relevant respiratory states with unique mechanics. These were (1) the respiratory transition to air-breathing from an entirely fluid-filled lung (rapid aeration and fall in resistance); (2) commencement of tidal ventilation in an acutely surfactant-deficient state (low compliance) and (3) exogenous surfactant therapy (improved aeration and compliance). Total, tidal, resistive and elastic-dynamic mechanical power were calculated from the flow, pressure and volume signals (200 Hz) for each inflation.
All components of mechanical power behaved as expected for each state. Mechanical power increased during lung aeration from birth to 5 min, before again falling immediately after surfactant therapy. Before surfactant therapy tidal power contributed 70% of total mechanical power, and 53.7% after. The contribution of resistive power was greatest at birth, demonstrating the initial high respiratory system resistance at birth.
In our hypothesis-generating dataset, changes in mechanical power were evident during clinically important states for the preterm lung, specifically transition to air-breathing, changes in aeration and surfactant administration. Future preclinical studies using ventilation strategies designed to highlight different types of lung injury, including volu-, baro- and ergotrauma, are needed to test our hypothesis.
在接受机械通气的成年人中，机械功率是导致肺损伤和死亡的主要因素。随着我们对机械功率理解的最新进展，不同的机械组成部分得以分离。早产肺具有许多相同的特征，这表明机械功率可能与该群体相关。迄今为止，机械功率在新生儿肺损伤中的作用尚不清楚。我们假设机械功率可能有助于拓展我们对早产肺病的理解。具体而言，机械功率测量可能有助于解释肺损伤起始方面的知识空白。
为了证明我们的假设，我们重新分析了澳大利亚墨尔本默多克儿童研究所数据库中的数据。选择了16只妊娠124 - 127天（足月为145天）的早产羔羊，它们从出生起通过带套囊的气管内导管接受90分钟的标准化正压通气，每只羔羊都暴露于三种不同且具有临床相关性、具有独特力学特征的呼吸状态。这些状态分别是：(1) 从完全充满液体的肺向呼吸空气的转变（快速通气和阻力下降）；(2) 在急性表面活性剂缺乏状态下开始潮气量通气（顺应性低）；(3) 外源性表面活性剂治疗（通气和顺应性改善）。根据每次充气的流量、压力和体积信号（200Hz）计算总机械功率、潮气量机械功率、阻力机械功率和弹性动力机械功率。
每种状态下机械功率的所有组成部分表现均符合预期。从出生到5分钟肺通气期间机械功率增加，在表面活性剂治疗后立即再次下降。在表面活性剂治疗前，潮气量功率占总机械功率的70%，治疗后占53.7%。阻力功率在出生时贡献最大，表明出生时呼吸系统初始阻力较高。
在我们的假设生成数据集中，在早产肺具有临床重要意义的状态下，特别是向呼吸空气的转变、通气变化和表面活性剂给药过程中，机械功率的变化是明显的。未来需要进行临床前研究，采用旨在突出不同类型肺损伤（包括容积伤、气压伤和角牵张伤）的通气策略来检验我们的假设。
