Smith P G, Falahat A, Carlo W A
Department of Pediatrics, Case Western Reserve University, Rainbow Babies and Childrens Hospital, Cleveland, OHio 44106.
J Appl Physiol (1985). 1992 Jun;72(6):2454-7. doi: 10.1152/jappl.1992.72.6.2454.
We studied the effect of increasing airway resistance on equilibration of airway and alveolar pressure during passive expiratory airflow interruption. In 10 anesthetized and paralyzed rabbits, airway and alveolar pressures were compared before and after airway resistance was increased with methacholine. In all studies, airway pressure rose to equilibrate with alveolar pressure immediately after the interruption (delta Pinit) regardless of increases in airway resistance. The pressures then remained equal during the interruption while gradually increasing to plateau (delta Pdiff). Before methacholine exposure, delta Pdiff was small (0.6 +/- 0.3 cmH2O). Steady-state resistance calculated from the sum of delta Pinit and delta Pdiff was similar to airway resistance calculated from delta Pinit alone. After methacholine, increased airway resistance was accompanied by increased delta Pdiff (2.0 +/- 0.5 cmH2O), causing disproportionate increase in steady-state resistance. delta Pdiff increases were equal in the airway and alveoli, implying resistive changes distal to the sampled alveoli. Thus increasing airway resistance did not delay pressure equilibration across airways. However, increases in airway resistance were accompanied by tissue resistive changes that were greater than the increases in airway resistance.
我们研究了在被动呼气气流中断期间增加气道阻力对气道与肺泡压力平衡的影响。在10只麻醉并麻痹的兔子中，比较了用乙酰甲胆碱增加气道阻力前后的气道压力和肺泡压力。在所有研究中，无论气道阻力如何增加，气流中断后气道压力立即上升至与肺泡压力平衡（初始压差delta Pinit）。然后在气流中断期间压力保持相等，同时逐渐增加至平台期（压差delta Pdiff）。在暴露于乙酰甲胆碱之前，delta Pdiff较小（0.6±0.3 cmH2O）。根据delta Pinit和delta Pdiff之和计算的稳态阻力与仅根据delta Pinit计算的气道阻力相似。使用乙酰甲胆碱后，气道阻力增加伴随着delta Pdiff增加（2.0±0.5 cmH2O），导致稳态阻力不成比例增加。气道和肺泡中的delta Pdiff增加量相等，这意味着采样肺泡远端存在阻力变化。因此，增加气道阻力不会延迟气道间的压力平衡。然而，气道阻力增加伴随着组织阻力变化，且该变化大于气道阻力的增加。
