Versprille A, Hrachovina V, Jansen J R
Department of Pulmonary Diseases, Erasmus University, Rotterdam, The Netherlands.
Intensive Care Med. 1995 Dec;21(12):1009-15. doi: 10.1007/BF01700663.
We tested whether alternating ventilation (AV) of each lung (i.e. with a phase difference of half a ventilatory cycle) would decrease central venous pressure and so increase cardiac output when compared with simultaneous ventilation (SV) of both lungs.
If, during AV, the inflated lung expands partly via compression of the opposite lung, mean lung volume will be smaller during AV than SV. As a consequence, mean intrathoracic pressure (as cited in the literature), and therefore, central venous pressure will be smaller.
The experiments were performed in seven anaesthetized and paralyzed piglets using a double-piston ventilator. Minute ventilation was the same during AV and SV. Starting at SV, we alternated three times between AV and SV for periods of 10 min.
During AV, central venous pressure was decreased by 0.7 mmHg and cardiac output was increased by 10 +/- 4.4% (mean, +/-SD) compared with SV. AV also resulted in increased arterial pressure. During one-sided inflation with closed outlet of the opposite lung, a pressure rise occurred in the opposite lung, indicating compression.
The higher cardiac output during AV than SV can be explained by the fact that central venous pressure is lower during AV. This lower central venous pressure is very probably due to the lower mean intrathoracic pressure caused by compression of the opposite lung during unilateral inflation.
我们测试了与双肺同步通气（SV）相比，单肺交替通气（AV，即通气周期相差半个周期）是否会降低中心静脉压从而增加心输出量。
如果在AV过程中，充气的肺部分通过对侧肺的压缩而扩张，那么AV期间的平均肺容积将比SV时小。因此，平均胸内压（如文献中所述）以及中心静脉压将会降低。
使用双活塞呼吸机对7只麻醉并麻痹的仔猪进行实验。AV和SV期间的分钟通气量相同。从SV开始，我们在AV和SV之间交替三次，每次持续10分钟。
与SV相比，AV期间中心静脉压降低了0.7 mmHg，心输出量增加了10±4.4%（平均值，±标准差）。AV还导致动脉压升高。在对侧肺出口关闭进行单侧充气时，对侧肺出现压力升高，表明存在压缩。
AV期间的心输出量高于SV，这可以通过AV期间中心静脉压较低这一事实来解释。这种较低的中心静脉压很可能是由于单侧充气期间对侧肺的压缩导致平均胸内压降低所致。
