Hedenstierna G, Santesson J
Acta Anaesthesiol Scand. 1976;20(3):248-54. doi: 10.1111/j.1399-6576.1976.tb05036.x.
Breathing mechanics and gas exchange were studied in 10 extremely obese subjects (average weight 138 kg) prior to and during anaesthesia with mechanical ventilation. Breathing mechanics were analysed from measurements of transpulmonary pressure (during anaesthesia, trans-chest wall pressure as well) inspiratory gas flow and tidal volume. Gas exchange was studied by analysing inspired and from the Bohr equation, and the division into anatomical and alveolar dead space was arrived at by capnography. The patients were anaesthetised with neuroltpt agents and ventilated with an air-oxygen mixture. Lung compliance during spontaneous breathing was below normal and decreased further during artificial ventilation. Chest wall compliance measured during anaesthesia was within normal limits. Lung resistance was above normal during spontaneous breathing and increased further during mechanical ventilation. Total dead space was normal during spontaneous breathing and increased moderately during artificial ventilation, the increment coming mainly from alveolar dead space. A moderate hypoxaemia was recorded during spontaneous breathing, and the alveolar-arterial oxygen tension difference was slightly elevated. During anaesthesia this difference was markedly greater. It is concluded that the most probable reason for the relative hypoxaemia is right-to-left shunting.
对10名极度肥胖受试者（平均体重138千克）在机械通气麻醉前及麻醉期间的呼吸力学和气体交换进行了研究。通过测量跨肺压（麻醉期间还测量胸壁跨压）、吸气气流和潮气量来分析呼吸力学。通过分析吸入气体并根据玻尔方程研究气体交换，通过二氧化碳描记法确定解剖死腔和肺泡死腔的划分。患者使用神经安定药物麻醉，并使用空气 - 氧气混合气体进行通气。自主呼吸时肺顺应性低于正常水平，人工通气期间进一步降低。麻醉期间测量的胸壁顺应性在正常范围内。自主呼吸时肺阻力高于正常水平，机械通气期间进一步增加。自主呼吸时总死腔正常，人工通气期间适度增加，增加主要来自肺泡死腔。自主呼吸期间记录到中度低氧血症，肺泡 - 动脉氧分压差略有升高。麻醉期间此差值明显更大。得出结论，相对低氧血症最可能的原因是右向左分流。
