体外循环心脏手术后早期呼吸功能的变化(用单次呼吸CO_2曲线进行的研究)

Pulmonary function changes during and after cardiopulmonary bypass.

用单次呼吸CO_2曲线的方法研究了心脏手术中和CPB停机早期呼吸功能的经时变化。结果显示:PaCO_2虽经调节通气量保持在正常范围内,但a-etDCO_2和A-aDO_2在CPB后明显增大。CO_2产生量在CPB后随时间延长而增加,使分钟通气量相应增加,平均气道压增高。总顺应性在CPB后有降低倾向。生理死腔率和肺泡死腔率在CPB后增大。结论认为,体外循环后早期呼吸功能降低的原因,主要是肺低灌注导致的通气/血流不配及CPB引起的肺瘀血和间质水肿所致气体交换功能下降。CPB后早期为改善通气功能,必须同时改善循环系统功能。

Pulmonary function changes during and after cardiopulmonary bypass were studied using single breath test for CO_2 (SBT-CO_2) in 16 adult patients undergoing cardiac surgery. The results showed that P_(A-a)CO_2 and P_(A-a)O_2 increased significantly after bypass though PaCO_2 kept in normal range by adjusting ventilation volume. The CO_2 production increased as time passed after bypass, resulting in the increase of required minute volume and the rise of airway pressure. Compliance showed a tendency to decrease, while physologic dead space and alveolar dead space increased significantly. It is concluded that the causes of pulmonary dysfunction occurring in early stage of post-bypass are mainly due to the V/Q mismatch induced by low perfusion of the lung. To improve the pulmonary function at the early stage of post-bypass, the circulatory function should be improved accordingly.