Gas exchange in the lung depends on tidal breathing, which brings new oxygen to and removes carbon dioxide from alveolar gas. This maintains alveolar partial pressures that promote passive diffusion to add oxygen and remove carbon dioxide from blood in alveolar capillaries. In a lung model without ventilation and perfusion (V̇_AQ̇) mismatch, alveolar partial pressures of oxygen and carbon dioxide are primarily determined by inspiratory pressures and alveolar ventilation. Regions with shunt or low ratios worsen arterial oxygenation while alveolar dead space and high lung units lessen CO₂ elimination efficiency. Although less common, diffusion limitation might cause hypoxemia in some situations. This review covers the principles of lung gas exchange and therefore mechanisms of hypoxemia or hypercapnia. In addition, we discuss different metrics that quantify the deviation from ideal gas exchange.

肺部的气体交换取决于潮式呼吸，潮式呼吸为肺泡气体带来新的氧气并去除二氧化碳。这可以维持肺泡分压，促进被动扩散，以增加氧气并去除肺泡毛细血管中血液中的二氧化碳。_{在没有通气和灌注（V̇ A} Q̇）不匹配的肺模型中，肺泡氧分压和二氧化碳分压主要由吸气压和肺泡通气量决定。有分流或低的区域 比率恶化动脉氧合，而肺泡死腔和高 肺单位降低CO ₂消除效率。尽管不太常见，但扩散限制在某些情况下可能会导致低氧血症。本综述涵盖了肺气体交换的原理以及低氧血症或高碳酸血症的机制。此外，我们还讨论了量化与理想气体交换的偏差的不同指标。