Gomes R F, Shardonofsky F, Eidelman D H, Bates J H
Meakins-Christie Laboratories, McGill University, Montréal, Québec, Canada H2X 2P2.
J Appl Physiol (1985). 2001 May;90(5):1631-8. doi: 10.1152/jappl.2001.90.5.1631.
The purpose of the present study was to establish how the dependence of respiratory mechanics on lung inflation changes during development. We studied seven groups of rats from 10 days to 3 mo of age at five levels of positive end-expiratory pressure (PEEP) from 0 to 7 hPa (1 hPa = 0.1 kPa approximately 1 cmH(2)O). At each PEEP level, we measured respiratory system resistance and elastance at both 0.9 and 4.8 Hz to partition the mechanical properties into its airway and tissue components. Elastance increased more rapidly with PEEP in the younger animals, which we interpret as reflecting a more pronounced strain stiffening of the younger parenchyma. However, the decrease in airway resistance with PEEP was more pronounced in the older animals. Morphometric analysis showed that mean tissue density decreased and total alveolar surface area increased with age. Our data suggest that the mechanical interdependence between airways and parenchyma is weaker in very young animals compared with mature animals. This may play a role in the hyperresponsiveness of immaturity.
本研究的目的是确定呼吸力学对肺膨胀的依赖性在发育过程中是如何变化的。我们研究了7组大鼠，年龄从10天到3个月，呼气末正压（PEEP）设置为5个水平，范围从0至7 hPa（1 hPa = 0.1 kPa，约等于1 cmH₂O）。在每个PEEP水平下，我们在0.9 Hz和4.8 Hz频率时测量呼吸系统阻力和弹性，以将力学特性分为气道和组织成分。在较年幼的动物中，弹性随PEEP增加得更快，我们将此解释为反映了较年幼实质组织更明显的应变硬化。然而，在较年长的动物中，气道阻力随PEEP的降低更为明显。形态计量学分析表明，平均组织密度随年龄降低，而总肺泡表面积随年龄增加。我们的数据表明，与成熟动物相比，年幼动物气道与实质组织之间的力学相互依赖性较弱。这可能在未成熟个体的高反应性中起作用。
