Maximal airway response in mature and immature rabbits during tidal ventilation.
Maximal airway response in mature and immature rabbits during tidal ventilation.
复制标题
潮气通气期间成熟和未成熟兔子的最大气道反应。
DOI：
10.1152/jappl.1995.79.4.1190
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Gunst,SJ
中科院分区：
文献类型：
--
作者：
Tepper,RS;Shen,X;Bakan,E;Gunst,SJ
采用肺泡胶囊对8只未成熟和8只成熟麻醉家兔在施加潮汐通气时的最大甲基胆碱（MCh）刺激下的气道关闭进行了评估。在呼气末正压为5 cmH2O时，测量MCh刺激期间气道开口、肺泡压（δ PA）和肺阻力（RL）的变化。在未成熟家兔中，δ PA在所有动物中均保持bbb30 cmH2O，表明未检测到气道关闭。这与我们之前在静态条件下分离的未成熟兔肺的研究形成对比，在静态条件下，最大MCh挑战时δ PA < 0.1 cmH2O，结果与气道关闭一致。在体内潮汐通气时，成熟动物也未发生气道关闭；然而，在静态条件下，孤立肺关闭的频率非常低。随着MCh的增加，未成熟家兔呼气末PA升高，而成熟家兔呼气末PA升高。在MCh期间，未成熟家兔的RL未达到平台期，而成熟家兔则达到平台期。未成熟家兔的RL也有更大的增加。这些结果表明，潮汐通气可以限制未成熟家兔在最大MCh刺激下的支气管收缩，防止气道关闭。潮汐通气可以通过伸展对气道平滑肌收缩的抑制作用以及引起过度充气从而增加肺压来限制支气管收缩。
Airway closure during maximal methacholine (MCh) challenge was evaluated using alveolar capsules in eight immature and eight mature anesthetized rabbits in vivo during imposed tidal ventilation. Changes in airway opening and alveolar pressures (delta PA) and pulmonary resistance (RL) were measured during MCh challenge at a positive end-expiratory pressure of 5 cmH2O. In immature rabbits, delta PA remained > 3 cmH2O in all animals, indicating no detectable airway closure. This contrasts to our previous study of isolated immature rabbit lungs under static conditions in which delta PA was < 0.1 cmH2O during maximal MCh challenge, findings consistent with airway closure. Airway closure also did not occur in mature animals during tidal ventilation in vivo; however, the frequency of closure in isolated lungs under static conditions was very low. With increasing MCh, end-expiratory PA increased in immature but not in mature rabbits. RL did not reach a plateau in immature rabbits during MCh, whereas a plateau was reached in mature rabbits. Immature rabbits also had greater increases in RL. These results suggest that tidal ventilation can limit bronchoconstriction in immature rabbits and prevent airway closure during maximal MCh challenge. Tidal ventilation may limit bronchoconstriction by inhibitory effects of stretch on airway smooth muscle contraction and also by causing hyperinflation and thereby increasing transpulmonary pressure.