Mutoh T, Lamm W J, Embree L J, Hildebrandt J, Albert R K
Medical Service, Veterans Administration Medical Center, Seattle, Washington.
J Appl Physiol (1985). 1991 Jun;70(6):2611-8. doi: 10.1152/jappl.1991.70.6.2611.
Abdominal distension (AD) occurs in pregnancy and is also commonly seen in patients with ascites from various causes. Because the abdomen forms part of the "chest wall," the purpose of this study was to clarify the effects of AD on ventilatory mechanics. Airway pressure, four (vertical) regional pleural pressures, and abdominal pressure were measured in five anesthetized, paralyzed, and ventilated upright pigs. The effects of AD on the lung and chest wall were studied by inflating a liquid-filled balloon placed in the abdominal cavity. Respiratory system, chest wall, and lung pressure-volume (PV) relationships were measured on deflation from total lung capacity to residual volume, as well as in the tidal breathing range, before and 15 min after abdominal pressure was raised. Increasing abdominal pressure from 3 to 15 cmH2O decreased total lung capacity and functional residual capacity by approximately 40% and shifted the respiratory system and chest wall PV curves downward and to the right. Much smaller downward shifts in lung deflation curves were seen, with no change in the transdiaphragmatic PV relationship. All regional pleural pressures increased (became less negative) and, in the dependent region, approached 0 cmH2O at functional residual capacity. Tidal compliances of the respiratory system, chest wall, and lung were decreased 43, 42, and 48%, respectively. AD markedly alters respiratory system mechanics primarily by "stiffening" the diaphragm/abdomen part of the chest wall and secondarily by restricting lung expansion, thus shifting the lung PV curve as seen after chest strapping. The less negative pleural pressures in the dependent lung regions suggest that nonuniformities of ventilation could also be accentuated and gas exchange impaired by AD.
腹胀（AD）在孕期会出现，在各种原因导致腹水的患者中也很常见。由于腹部是“胸壁”的一部分，本研究的目的是阐明AD对通气力学的影响。在五只麻醉、麻痹并接受机械通气的直立猪身上测量气道压力、四个（垂直）区域胸膜压力和腹部压力。通过向置于腹腔内的充液气球充气来研究AD对肺和胸壁的影响。在腹部压力升高前及升高后15分钟，从肺总量放气至残气量以及在潮气量呼吸范围内测量呼吸系统、胸壁和肺的压力-容积（PV）关系。将腹部压力从3 cmH₂O升高至15 cmH₂O可使肺总量和功能残气量降低约40%，并使呼吸系统和胸壁PV曲线向下并向右移位。肺放气曲线的下移幅度小得多，跨膈PV关系无变化。所有区域胸膜压力均升高（负值减小），在依赖区域，功能残气量时接近0 cmH₂O。呼吸系统、胸壁和肺的潮气量顺应性分别降低43%、42%和48%。AD主要通过使胸壁的膈肌/腹部部分“变硬”，其次通过限制肺扩张来显著改变呼吸系统力学，从而使肺PV曲线移位，如同胸部捆绑后的情况。依赖肺区域胸膜压力负值减小表明，AD还可能加剧通气不均匀性并损害气体交换。
