Deoras K S, Wolfson M R, Bhutani V K, Shaffer T H
Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
Pediatr Res. 1989 Nov;26(5):434-7. doi: 10.1203/00006450-198911000-00014.
Compliant immature airways sustain significant deformation following positive pressure ventilation. To evaluate the structural changes induced by in vivo positive pressure ventilation, tracheae of preterm lambs (107-116 d gestational age) were studied histologically. Nonventilated (group I: n = 7) and ventilated (group II: n = 7) tracheal segments were excised and studied by histologic and morphometric techniques. Computerized image analysis was used to measure dimensions of tracheal wall components and of the tracheal section. The circumference, diameter, and cross-sectional area of the section as well as the length of the trachealis muscle were significantly greater; although the thickness of the muscle and cartilage were seen to be significantly lower in group II sections compared to group I sections. Also, in comparison to group I, in group II sections there was lesser overlap of the posterior free ends of tracheal cartilage and the epithelial layer was flattened and focally abraded. Our findings demonstrate structural changes in the airway of preterm animals and characterize alterations in the geometric arrangement of muscle and cartilage after PPV. These results suggest possible structural mechanisms for the functional changes seen during and subsequent to mechanical ventilation.
顺应性不成熟气道在正压通气后会发生显著变形。为评估体内正压通气引起的结构变化，对早产羔羊（胎龄107 - 116天）的气管进行了组织学研究。切除未通气（第一组：n = 7）和通气（第二组：n = 7）的气管段，并采用组织学和形态计量学技术进行研究。利用计算机图像分析测量气管壁各成分以及气管截面的尺寸。截面的周长、直径和横截面积以及气管肌的长度显著更大；尽管与第一组切片相比，第二组切片中肌肉和软骨的厚度明显更低。此外，与第一组相比，第二组切片中气管软骨后游离端的重叠较少，上皮层扁平且有局灶性磨损。我们的研究结果表明早产动物气道存在结构变化，并描述了正压通气后肌肉和软骨几何排列的改变。这些结果提示了机械通气期间及之后所见功能变化的可能结构机制。
